Pathophysiology 2024/2025 Lecture Notes PDF

PATHOPHYSIOLOGY 2024/2025 INTRODUCTION Prof. Dr. Zoltán Rakonczay, MD, PhD, DSc Chairman Albert Szent-Györgyi Medical School Department of Pathophysiology LECTURERS, DEPARTMENT OF PATHOPHYSIOLOGY Dr. Zsolt Bagosi Dr. Krisztina Csabafi...

PATHOPHYSIOLOGY 2024/2025 INTRODUCTION Prof. Dr. Zoltán Rakonczay, MD, PhD, DSc Chairman Albert Szent-Györgyi Medical School Department of Pathophysiology LECTURERS, DEPARTMENT OF PATHOPHYSIOLOGY Dr. Zsolt Bagosi Dr. Krisztina Csabafi Dr. Miklós Jászberényi Associate Professor Associate Professor Associate Professor Educational affairs, TDK advisor Dr. Zoltán Rakonczay Dr. Márta Sárközy Dr. Júlia Szakács 2 Professor and chairman Associate Professor Senior Assistant Professor  PATHOPHYSIOLOGY (AND ECG) We will teach you the following about various diseases/disorders o definition o etiology o pathogenesis/pathomechanism o main symptoms Indispensable subject for your clinical studies Based on previous knowledge Close association with pathology and microbiology Basics of ECG analysis (practicals) Text books/notes/videos o Hammer & McPhee. Pathophysiology of Disease: An Introduction to Clinical Medicine. McGraw-Hill, Lange Medical Books, 2019, 8th edition o Thaler. The Only EKG Book You'll Ever Need. Wolters Kluwer, 2019, 9th edition o Csabafi et al. ECG guide, 2024 – notes o ECG videos made by the Department (YouTube) Lecture notes and other teaching materials (lecture and practice schedules, exam topics, 3 learning guide and reference values) can be downloaded from Coospace  COURSE REQUIREMENTS Students must follow all general regulations of the University/Faculty as well as the specific regulations of the Department Attending lectures is not compulsory The attendance of students at practicals/seminars is mandatory Students are not allowed to miss more than 3 seminars per semester (25%) In case of 4 or more absences only an authentic medical certificate or the Dean’s Approval will be accepted by the Department’s chairman, and the missed classes should be made up If the latter absences are not made up, signing of the semester will be denied In such a case, you can not register for an exam and the whole course (lectures and practicals) of the semester has to be repeated 4  MIDTERM EXAMS (MTOs) Held on the 7th and 13th weeks of the semester (35 questions) ECG analysis (exam during practicals) @ 10th week Attendance is mandatory Retake is not possible Students who miss the MTOs and do not submit an official written documentation of verification of illness will get 0% or fail The MTO results will provide the basis of your practical grade, but the practical teacher may also conduct separate assessments during the practicals Based on your practical grade, you may be eligible for a 1st semester exam grade offer 5  PROCESS OF 1st SEMESTER EXAMS Grade offer (good or excellent): based on the results of MTOs Registration via NEPTUN Identify yourself at the time and place of the exam Consists of written (30 min, 10 SAQ) and oral (ECG analysis + 2 topics) parts PLEASE NOTE Successful 1st semester exam is required to complete your 2nd semester studies! There will be possibility for taking on a 1st semester exam course in the 2nd semester 6  GENERAL EXPECTATIONS DURING EXAMS You should rely on your own knowledge - in case of cheating, you will be sanctioned Lack of appropriate knowledge in any one of the topics will terminate the exam with grade 1 (fail) You should not make a big mistake during your exam and there should be no gaps in your basic knowledge We expect you to possess basic (anatomical, biochemical and physiological) knowledge essential for understanding pathophysiology You must know all reference values 7  SCIENTIFIC CIRCLE (TDK) TOPICS Tutor Topic Júlia Szakács M.D., Ph.D. Study of the behavioral effects of neuropeptides The pathophysiology of Alzheimer’s disease Miklós Jászberényi, M.D., Ph.D., D.Sc. The role of neuropeptide mediators in the control off affective, emotional and cognitive processes The effect of neuropeptides on the Hypothalamus-Pituitary-Adrenal system The role of CRF and urocortins in social interaction The role CRF and urocortins in drug addiction Zsolt Bagosi, M.D., Ph.D. The effects of neuropeptides on hypothalamic neurohormones The effects of neuropeptides on extra-hypothalamic neurotransmitters The effect of kisspeptin on amyloid-beta neurotoxicity Effect of kisspeptins on carbohydrate metabolism Krisztina Anna Csabafi, M.D., Ph.D. Effect of neuropeptides on nociception and morphine induced analgesia, tolerance Krisztina Anna Csabafi, M.D., Ph.D. Role of neuropeptides in anxiety and the development of anxious phenotype Katalin Eszter Ibos, M.D. Zoltán Rakonczay, M.D., Ph.D., D.Sc. The pathomechanism of experimental acute pancreatitis and therapeutic Lóránd Kiss, Ph.D. investigations Investigation of novel molecular mechanisms and therapeutic targets in models of Márta Sárközy, M.D., Ph.D. heart failure with different aetiologies István Koncz, M.D., Ph.D. Cardiac arrhythmias. Cardiac electrophysiological effects of drugs 8  INFLAMMATION 1. Prof. Dr. Zoltán Rakonczay, MD, PhD, DSc Albert Szent-Györgyi Medical School Department of Pathophysiology Modified notes (from 2018) of Dr. Krisztina Csabafi and Prof. Dr. Gyula Szabó with contributions from Dr. Zsolt Bagosi Reviewed by Prof. Zsuzsanna Bata, Prof. László Kovács and Prof. Tibor Hortobágyi  INFLAMMATION 1: OVERVIEW Basic concepts Causes Forms Sequence of events Cells involved in the inflammatory response ○ Endothelial cells, Leukocytes (Neutrophil granulocytes, Monocytes / macro- phages, Mast cells and basophilic granulocytes, Eosinophil granulocytes, Lymphocytes), Platelets Mediators of inflammation ○ Plasma-derived  Coagulation factors, Plasma kinins, Fibrinolytic system, Complement system ○ Cell-derived  Vasoactive amines, Cell-membrane phospholipid-derived compounds, Cytokines, Reactive oxygen species, Nitrogen monoxide and reactive nitrogen species, Neurokines, Stress proteins Pathomechanism of acute inflammation: stages ○ Alteration and exudation ○ Amplification, proliferation & destruction ○ Termination Outcome of acute inflammation 10  INFLAMMATION BASIC CONCEPTS A response of vascularized tissue to cellular injury, to bring molecules of host defense and inflammatory cells to the site of injury in order to destroy, dilute or wall off the harmful agents Part of normal, everyday life; indispensable for survival (protective) Follows a sequence of specific events that occur in response to nonspecific (exogenous and endogenous) agents o Serves to eliminate both the initial cause of cell injury (e.g., microbe toxins) and the consequences of such injury o Restricts tissue damage to smallest possible area o Prepares injured area for healing by an active mechanism Leads to stereotypic small vessel and leukocyte (WBC) responses The inflammatory and regenerative reactions may cause serious damage Local signs: redness, heat, pain, swelling and often loss of function 11 INFLAMMATORY RESPONSE Rossi et al. Front. Immunol. 2021; 12:595722. 12  INFLAMMATION CAUSES Exogenous ○ Biological: LPS (endotoxin), bacteria, virus, fungus, parasite, snake-, insect-, spider-, jellyfish-, etc. derived agents ○ Mechanical: physical trauma (injury), foreign body, surgery ○ Physical: burn, frost, UV (sunburn), ionizing radiation ○ Chemical: acid, alkali, organic solvents, tobacco smoke Endogenous ○ Perfusion abnormalities: ischemia-reperfusion, thrombosis, embolism ○ Protease-activated: acute pancreatitis, shock ○ Missing protease inhibitors: congenital – emphysema, angioneurotic edema; acquired: chronic arthritis, shock, ARDS ○ Macromolecules: autoimmunity, immune complex disease ○ Micromolecules: e.g. urate crystals ○ Toxins (uremic toxins, ammonia, etc.) 13 INFLAMMATION FORMS , Innate and , fibroblasts 14  INFLAMMATION SITE AND SEQUENCE OF EVENTS Extracellular matrix including Microcirculatory system Arterioles Precapillary sphincters Capillaries Venules Interstitium 15 Kumar, Abbas, Aster. Robbins & Cotran Pathologic Basis of Disease, 2015  INFLAMMATION: INITIATION Damage associated molecular patterns (DAMPs) Signals released from malfunctioning or dead cells and from damaged tissues Bioactive peptides released from nociceptors Pattern in response to pain recognition Constitutively expressed intracellular proteins receptors (PRR) released upon cell damage (heat-shock proteins, mitochondrial peptides) ATP Recognize PAMPs and DAMPs Pathogen associated Found on inflammatory and immune cells molecular patterns (PAMPs) Soluble and membrane bound forms E.g.: toll-like receptors, NOD, mannose Signals released or produced by binding lectin, C-reactive protein, pathogens such as bacteria and surfactant, scavenger receptors virus for which the host has evolved a corresponding set of receptors that detects their presence purpose: activate inflammatory and immune cells LPS, exotoxins 16  Inflammation *See plasma-derived “sentinel” mediators of inflammation Injury on page 31 Mast cell Hageman factor DAMPs Histamine, 5HT, coagulation system proteases, PG, LT, PAMPs cytokines Thrombin Endothelial fibrinolytic system cell FDP Macrophage kallikrein-kinin system Bk complement system C3a, C5a 17 interstitium intravascular compartment  INFLAMMATION SEQUENCE OF EVENTS Nervous Acute Acute Chronic Healing response vascular cellular cellular Scar Causative agent Lymphocyte Fibrin Edema Pus Macrophage emigration infiltration deposition Exudate RBC Neutrophil extravasation Fibrosis granulocytes Transudate Sympathetic nervous system Vasoconstriction Permea- Chemotaxis bility ↑ Endothelial cell contraction Mastocyte degranulation 18 Pre-capillary arteriole Capillary Post-capillary venule  CELLS INVOLVED IN THE INFLAMMATORY RESPONSE 1. Endothelial cells 2. Neutrophil granulocytes 3. Monocytes/macrophages 4. Mast cells and basophilic granulocytes Leukocytes (WBCs) 5. Eosinophil granulocytes 6. Lymphocytes 7. Platelets Can have overlapping functions during inflammation There is interaction between resident tissue cells and inflammatory cells 19  CELLS INVOLVED IN THE INFLAMMATORY RESPONSE 1. Endothelial cells ○ Physiologic role: barrier between the vessel lumen and surrounding tissue, anti-thrombotic effect, generate vasodilator and vasoconstrictor substances NO Endothelin 1-3: vessel smooth muscle contraction Arachidonate products □ Vasoconstriction: TxA2, PGH2; vasodilation: PGI2 Cytokines: IL-1, IL-6, TNF-α Anticoagulants: heparin-like molecules, thrombomodulin Fibrinolytic substances: tissue-type plasminogen activator Prothrombotic substance: von Willebrand factor ○ In inflammation: express adhesion molecules, activate white blood cells, and generate inflammatory mediators 20 CELLS INVOLVED IN THE INFLAMMATORY RESPONSE LEUKOCYTE RECRUITMENT MARGINATION Postcapillary venule 21 Kumar, Abbas, Aster. Robbins Basic Pathology, 2018  CELLS INVOLVED IN THE INFLAMMATORY RESPONSE LEUKOCYTE RECRUITMENT 1. Margination: Blood flow slows early in inflammation (stasis), hemodynamic conditions change (wall shear stress decreases), and more white cells assume a peripheral position along the endothelial surface. 2. Rolling: Interactions are mediated by a family of proteins called selectins. There are three types of selectins: L- selectin expressed on leukocytes, E-selectin on endothelium, and P-selectin on platelets and on endothelium. The ligands for selectins are sialylated oligosaccharides bound to mucinlike glycoprotein backbones. 3. Firm adhesion: Mediated by a family of heterodimeric leukocyte surface proteins called integrins. Activated Adhesion molecules endothelial cells express ligands for integrins (VCAM-1 and Selectins (P, E, L), ICAM-1). Addressins (sialyl-Lewis X: PS-GL-1, ES-L-1) 4. Transmigration: Occurs mainly in postcapillary venules Immunoglobulin superfamily either via paracellular or transcellular diapedesis. (ICAM-1, VCAM-1) Integrins (ß-2, ß-1) 22 CELLS INVOLVED IN THE INFLAMMATORY RESPONSE LEUKOCYTE ACTIVATION 23 Kumar, Abbas, Aster. Robbins Basic Pathology, 2018 CELLS INVOLVED IN THE INFLAMMATORY RESPONSE 2. Neutrophil granulocytes – the most important elements in acute inflammation Contain specific cytoplasmic granules Primary (azurophilic) □ Neutral and acidic protease □ Bactericidal protein: kills gram-negative bacterium □ Defensins: bacterium, fungus, virus killing, can also damage host tissue; have chemotactic role □ Lysozyme: disintegrates gram-positive bacterial wall □ Myeloperoxidase: production of reactive oxygen species Secondary (specific) □ Lactoferrin: binds iron (competes for iron with bacterium); stimulates oxygen- dependent killing mechanism ( OH) □ Lysozyme Tertiary (small storage granules): proteins released from these facilitate diapedesis during chemotaxis On the surface of neutrophil granulocytes: IgG and M Fc, toll-like receptor, N-formyl peptide-, complement- and IL-8 receptors Upon stimulation complement fragments (C5a, C3b), reactive oxygen species, LT, TxA2, and PGE2 are produced Natural senescence of granulocytes: granulocytes are cleared by macrophages without inflammatory process; the process is called efferocytosis (see later) 24  Activated neutrophils extrude nuclear material > extracellular viscous Neutrophil extracellular traps (NETs) meshwork of nuclear chromatin binds and concentrates granule proteins such as anti-microbial peptides and enzymes NET activation and release, or NETosis, is a dynamic process that can come in two forms, suicidal (slow cell death) and vital (non-lytic) Prevent the spread of the microbes by trapping them in the fibrils (bacterial protease resistant) Histones and associated DNA may be a source of nuclear antigens in systemic autoimmune diseases, particularly systemic lupus erythematosus 25 Brinkmann & Zychlinsky. Nat Rev Microbiol, 2007. CELLS INVOLVED IN THE INFLAMMATORY RESPONSE 3. Monocytes/macrophages ○ In the circulation: monocyte; upon stimulation by T-cell derived cytokines (IFN-γ) or bacterial endotoxin (LPS) emigrate as macrophage to the site of injury (24- 48 hr). Occur all over the body (e.g. microglia, Kupffer cells, sinus histiocytes, alveolar macrophages) ○ Multipotential cells, depending upon the cytokine stimulation their effector function will be different ○ Macrophages are the main effector cells of inflammation in tissue; especially to sustain chronic inflammation Cytotoxicity Immunosuppression Tissue damage Tissue repair 26 CELLS INVOLVED IN THE INFLAMMATORY RESPONSE PROPERTIES OF NEUTROPHILS AND MACROPHAGES 27 Kumar, Abbas, Aster. Robbins Basic Pathology, 2018 CELLS INVOLVED IN THE INFLAMMATORY RESPONSE 4. Mast cells and basophilic granulocytes ○ Cell surface receptors: toll-like, complement, mannose, platelet activating factor (PAF) and Fcε (IgE-specific) ○ Upon stimulation the cells liberate/generate: histamine, serotonin, heparin, TNF-α, LT-s (B4, C4, D4, E4), PAF, neutrophil chemotactic factor (IL-8), eosinophil chemotactic factor, protease (tryptase, chymase), anti-microbial proteins (defensins) ○ Histamine – 1st mediator of initial inflammatory response, causes dilation of arterioles and an increase in permeability of capillaries and venules Released by mast cells and basophils in response to injury (trauma, heat), immune reactions (IgE-mast cell FcR), anaphylatoxins (C3a, C5a fragments), cytokines (IL-1, IL-8), neuropeptides, leukocyte-derived histamine-releasing peptides ○ Serotonin (5-HT) – causes vasodilation and increased vascular permeability 5-HT release triggered by platelet aggregation (platelet dense-body granules) 28 CELLS INVOLVED IN THE INFLAMMATORY RESPONSE 5. Eosinophil granulocytes ○ Express IgA receptor and contain eosinophil basic protein –participate in helminthic infestation ○ Key players in Ig-E-mediated reactions (hypersensitivity, allergy, asthma) 6. Lymphocytes ○ Cells of adaptive immunity, present in the circulation and in various lymphoid organs; T (60-70%) and B cells ○ T cells: express T-cell receptor (TCR) which recognize peptide antigens presented by MHC molecules  CD4+ T cells: TH1 (IFN-γ, activates macrophages by the classical pathway), TH2 (IL-4, IL-5, and IL-13, which recruit and activate eosinophils and are responsible for the alternative pathway of macrophage activation) and TH17 (IL-17, induces the secretion of chemokines responsible for recruiting neutrophils and monocytes)  CD8+ T cells (cytotoxic T lymphocytes, CTLs) directly kill virus-infected cells and tumor cells  Regulatory T lymphocytes: suppress immune responses  NKT cells: recognize microbial glycolipids and may play a role in defense against some infections (innate immune response) ○ B cells: recognize antigen by means of membrane-bound IgM, differentiate into plasma cells after stimulation 29 CELLS INVOLVED IN THE INFLAMMATORY RESPONSE 7. Platelets ○ Participate in normal hemostasis (adhesion, aggregation and degranulation upon contact with collagen or thrombin) ○ Granules Dense granules: serotonin (5-HT), Ca2+, ADP α granules: fibrinogen, clotting factors, PDGF Lysosomes: acidic hydrolases ○ Their role in inflammation: vasodilation (5-HT), increased vascular permeability and smooth muscle contraction (TxA2) 30  MEDIATORS OF INFLAMMATION I. Plasma-derived o Many in “pro-form” requiring activation (enzymatic cleavage → cascades) o Coagulation factors o Plasma kinins o Fibrinolytic system o Complement system II. Cell-derived o Pre-formed, sequestered and released (vasocative amines: histamine and serotonin) o Synthesized as needed (prostaglandins, leukotrienes, cytokines) o White blood cell-derived factors (see before) 31  PLASMA-DERIVED MEDIATORS OF INFLAMMATION Negative surface, LPS Endothelial damage Urate crystal Enzymes (trypsin, plasmin) HMWK Hageman factor activation Exogenous and endogenous protease Pollen, mold, insect, bacterium Activation of the Xa, neutrophilic protease, kallikrein clotting cascade Prekallikrein Protease-activated Prothrombin Thrombin receptors Kallikrein Plasminogen Fibrin Fibrinogen Acute inflammation Activation of the fibinolytic system Vasodilatation, smooth HMWK Plasmin muscle contraction, Bradykinin proliferation Pro-inflammatory Increased vascular Activation of the FDP permeability changes in complement system atherosclerosis and re- Vasodilatation Increased vascular Pain stenosis permeability Smooth muscle contraction Chemotaxis 32 Anaphylatoxins  PLASMA-DERIVED MEDIATORS OF INFLAMMATION Activation of Hageman factor (XII) plays a key role in generation of plasma-derived mediators 1. Activation of coagulation cascade Responsible for making a fibrous network at the site of a lesion to trap exudates, microorganisms, and foreign bodies, stops bleeding and provides a framework for repair to begin Thrombin binds to protease-activated receptors (PAR) on platelets, leukocytes and endothelial cells. Activation of PAR facilitates inflammatory processes (chemokines↑, adhesion molecules (ICAM, VCAM) ↑, P-selectins ↑, COX-2↑, PAF↑, NO↑) 33 PLASMA-DERIVED MEDIATORS OF INFLAMMATION 2. Activation of kinin system: prekallikrein → kallikrein (amplification of inflammation) Bradykinin □ B1 receptor activation increases inflammatory response; Causes an increase in capillary permeability and pain, may increase leukocyte chemotaxis, generation of prostaglandins, cytokines (IL-s and TNF-α), NO and tachykinins □ B2 receptor: constitutive activation – vasodilation, NO and PG synthesis, natriuresis Inactivation by kininases (e.g. angiotensin converting enzyme) 34 PLASMA-DERIVED MEDIATORS OF INFLAMMATION 3. Activation of fibrinolytic system: plasminogen → plasmin Activation of fibrinolysis, splitting of complement cascade components, generation of pro-inflammatory “anaphylatoxins” C4a, C3a & C5a splitting the fibrin net will release the pro-inflammatory Fibrin degradation products (FDP) which will be involved in endothelial activation 4. Activation of alternative and lectin pathways of the complement system Endotoxin and mannose (bacterial origin) activates the pathways Complement components chemotactic to neutrophils and monocytes Main effects: 1. Anaphylatoxins: C4a, C3a, and C5a (smooth muscle cell contraction, increased permeability) 2. Opsonins: C3b, iC3b, C4b (increased phagocytosis) 3. Chemotaxis: C5a, C4a 4. Cell lysis: MAC (C5-9) 35 PLASMA-DERIVED MEDIATORS OF INFLAMMATION COMPLEMENT SYSTEM Anaphylatoxins: C3a, C4a, and C5a 36  CELL-DERIVED MEDIATORS OF INFLAMMATION 1. Vasoactive amines ○ Histamine (mast cells) ○ Serotonin [5-HT] (platelets) 2. Cell-membrane phospholipid-derived compounds ○ Platelet activating factor (PAF) Generated from membrane phospho-lipids by phospholipase A2 in inflammatory, endothelial, injured cells and platelets Causes vasodilatation (5-HT), increased vascular permeability & leukocyte adhesion Potent broncho-constrictor Causes platelet aggregation and degranulation 37  CELL-DERIVED MEDIATORS OF INFLAMMATION 2. Cell-membrane phospholipid-derived compounds (ctd.) ○ Arachidonic acid (AA) metabolites a. Cyclooxygenase pathway (COX1 and COX2) □ Thromboxane A2 (TxA2): potent platelet aggregator and vasoconstrictor (produced by platelets) □ Prostacyclin (PGI2): vasodilator and inhibitor of platelet aggregation (produced by endothelial cells) □ Prostaglandins (PGE2, PGD2, PGF2): vasodilatation, potentiate edema and pain, induces fever b. Lipoxygenase pathway (5-LOX) □ Leukotriene (LT) B4: potent chemo attractant causing neutrophil aggregation and adhesion to endothelial cells □ LTC4, D4, E4 (slow-reacting substance of anaphylaxis, SRSA): vasoconstriction, bronchoconstriction and increased vascular permeability (important in type I hypersensitivity) □ Lipoxins: (synthesized from precursors by 12-LOX in neutrophil granulocytes and thrombocytes) 38 □ Pro- and anti-inflammatory (15-epi LX) effects CELL-DERIVED MEDIATORS OF INFLAMMATION 39 Kumar, Abbas, Aster. Robbins Basic Pathology, 2018  CELL-DERIVED MEDIATORS OF INFLAMMATION 3. Cytokines ○ Soluble mediators („inflammatory hormones”) secreted by many cell types after a variety of stimuli ○ Act locally at very low concentrations in an autocrine, paracrine or endocrine manner (IL-1 – fever) on specific (usually tyrosine kinase) receptors ○ Effects are pleiotropic (one cytokine acts on many different cells) and redundant (many cytokines produce same/similar effects) ○ Interactions can be synergistic, inhibitory or modulating ○ Affect hematopoiesis, regulate innate & acquired immune response, inhibit viral replication, direct cell migration and have proinflammatory effect 40 CELL-DERIVED MEDIATORS OF INFLAMMATION TYPES OF CYTOKINES Pro-inflamma- Interleukins Growth factors Chemokines Interferons tory cytokines IL-1 IFN-a GM-CSF CC TNFa IL-6 IFN-ß M-CSF CXC IL-8 IFN-γ IL-13 XC IL-10 CX3C Fever Anorexia Inflammatory Macrophage Shock response stimulation Leukocyte Leukocyte Cytotoxicity Bactericide activation activation Cytokine effect Leukocyte Antiviral induction NK and chemotaxis effect Endothelial dendritic cell and tissue cell function activation 41 CELL-DERIVED MEDIATORS OF INFLAMMATION MAJOR ROLES OF CYTOKINES IN ACUTE INFLAMMATION 42 Kumar, Abbas, Aster. Robbins Basic Pathology, 2018  CELL-DERIVED MEDIATORS OF INFLAMMATION Central role of IL-1 and TNF-α in amplification of inflammatory response Gram negative Immune complexes T cell bacterium Toxin, physical, chemical stimulus TNF-a, IL-12 NK cell Macrophage Lysteria monocytogenes Effect of LPS in inflammatory response TNF-a (endothelial-leukocyte adherence) IL-8 (leukocyte recruitment) IL-1, 6 (acute phase response) IL-1, 6, 12 (immune regulation) 43  CELL-DERIVED MEDIATORS OF INFLAMMATION 4. Reactive oxygen species (ROS) / free radicals A free radical is literally any atom or molecule which contains one or more unpaired electrons, making it more reactive than the stable species ○ Superoxide radicals (O2-) – remain at the site of generation ○ Superoxide radical can be generated: Spontaneously in the mitochondrion as a result of „inaccuracies” of electron transport In the endothelial cells upon the effects of flavo-enzymes (xanthine oxidase) and cyclooxygenase or lipoxygenase □ Xanthine → uric acid: superoxide, hydrogen peroxide and hydroxyl radical is generated During inflammation in leukocytes > in endothelial cells from NADPH oxidase 44 CELL-DERIVED MEDIATORS OF INFLAMMATION REACTIVE OXYGEN SPECIES SOD – superoxide dismutase GPX – glutathione peroxidase catalase 45 CELL-DERIVED MEDIATORS OF INFLAMMATION REACTIVE OXYGEN SPECIES 46  CELL-DERIVED MEDIATORS OF INFLAMMATION REACTIVE OXYGEN SPECIES ○ Hydrogen peroxide – highly diffusible Unstable O2- quickly forms stable H2O2 and then water Too much H2O2 → hypochlorous acid and hydroxyl radical is generated ○ Hypochlorous acid (HOCl) In neutrophils myeloperoxidase enzyme in the presence of halides: H2O2 → HOCl HOCl acts on metalloprotease and inactivates α-1 antitrypsin → cell death ○ Hydroxyl radical ( OH) the most reactive radical; bactericide activity; formed by H2O2 reduction 47  CELL-DERIVED MEDIATORS OF INFLAMMATION REACTIVE NITROGEN SPECIES 5. Nitrogen monoxide (NO) / nitric oxide NO and reactive nitrogen species (RNS) Gas produced by endothelial cells and macrophages; short lasting, quickly diffusible Produced by 3 nitric oxide synthase (NOS) enzymes □ Neuronal (nNOS): constitutive □ Endothelial (eNOS): constitutive □ Inducible (iNOS): in inflammation Effects of NO are pleiotropic: □ Smooth muscle relaxation and vasodilation (eNOS) □ In activated macrophages, bacterial killing □ Inhibits thrombocyte adhesion, aggregation and degranulation □ NO and O2- overproduction → highly toxic ONOO- (peroxinitrite) and S-nitrosothiol radical is formed, but can acts as O2- scavenger 48  CELL-DERIVED MEDIATORS OF INFLAMMATION NITROGEN OXIDE (e.g. IL-1, TNFα, IFNγ) 49 49  CELL-DERIVED MEDIATORS OF INFLAMMATION 6. Neurokines (Substance P, neurokinin A and B) ○ Maintain communication between the endocrine-, nervous- and immune system ○ During inflammation, damage to nerve endings increases neurokine levels and inflammatory mediators: histamine, NO, kinins ○ Play an important role in pain perception ○ Act on neurokinin receptors (NK1, NK2) 7. Stress (heat-shock) proteins ○ Proteins up-regulated upon oxidative stress and inflammation ○ Decrease the expression of pro-inflammatory cytokines and NADPH function, increases NO-mediated cytoprotection and collagen 50 synthesis  ACUTE INFLAMMATION PATHOMECHANISM: STAGES 1. Alteration (in vascular caliber) and exudation (edema) Stereotypic, immediate response that leads to release of mediators, vasodilation and rapid flooding of injured site with fluid. 2. Amplification, proliferation & destruction Depending on the extent of injury, more mediators are released and inflammatory cells recruited to the site leading to phagocytosis and enzymatic/non-enzymatic processes that aim to reduce or eliminate the inciting agent. 3. Termination (katabasis, resolution) Activation of anti-inflammatory mechanisms; attenuate cell migration and promote the apoptosis and clearance of leukocytes from the inflammatory site. 51  ACUTE INFLAMMATION ALTERATION & EXUDATION http://homepage.smc.edu/ wissmann_paul/physiology textbook/OncoticPressure. html 1. Brief arteriolar vasoconstriction (SNS-mediated; sec-mins) 2. Precapillary arteriolar vasodilation; hyperemia (warmth & redness) □ Opens microvascular bed → increased intravascular (hydrostatic) pressure → early transudate [fluid with low protein content (specific gravity1.020) □ Exudate increases interstitial oncotic pressure → edema development (water and ions) 4. Blood flow in dilated capillaries and venules slows (congestion) 5. Intravascular stimulation: soluble & cellular mediators accumulated at the site of inflammation 52  ACUTE INFLAMMATION ALTERATION & EXUDATION: TRIPLE RESPONSE OF LEWIS 53  ACUTE INFLAMMATION ALTERATION AND EXUDATION Plasma derived Fibrin Plazma eredetű Coagulation/fibrinolysis degradation activation Hageman (XII) factor products (FDP) activation Kallikrein-kinin system Bradykinin activation Complement system C3a, C5a activation Mast and basophil Histamine cells Vasodilation Platelet Serotonin Increased permeability Edema Platelet activating Inflammatory exudates – contain plasma, cells and fluid Inflammatory cells factor (PAF) A. Serous – largely plasma, high in protein, occurs early or Prostaglandins in mild inflammation Leukotriens B. Fibrinous – large amounts of fibrinogen, forms a thick, sticky meshwork. Only removed by fibrolytic enzymes. Failure of removal leads to influx of fibroblasts and scar Nitrogen monoxide tissue formation Platelet activating C. Purulent – contains pus (remains of WBCs, protein and Endothelial cells tissue debris). factor (PAF) Prostaglandins D. Hemorrhagic – damage to blood vessels, occurs with Cell derived other forms of exudate E. Catarrhal – mucus hypersecretion that accompanies inflammation of a mucus membrane 54  ACUTE INFLAMMATION EXUDATION Mechanisms of increased vascular permeability (leakage) 1. Histamine, bradykinin, leukotrienes cause an early, brief (15 – 30 min) immediate transient response in the form of reversible endothelial cell contraction that widens intercellular gaps of venules (not arterioles or capillaries) 2. Cytokine mediators (TNF, IL-1) induce: – reversible endothelial cell junction retraction through cytoskeleton reorganization (4 – 6 hrs post injury, lasting 24 hrs or more) 3. Direct endothelial cell damage 4. Leukocyte-dependent endothelial cell injury 5. Transcytosis (?): intracellular vesicles extend from the luminal surface to basal lamina surface of the endothelial cell (e.g. in response to VEGF) 55  ACUTE INFLAMMATION EXUDATION Responses of the microvasculature to injury o During mild vasoactive mediator-induced injury endothelial cells separate and permit fluid to move out o With severe direct injury, the endothelial cells form blebs and separate from the BM 56  ACUTE INFLAMMATION AMPLIFICATION, PROLIFERATION & DESTRUCTION Amplification: activation of kinin and complement system Proliferation & destruction: acute cellular response o Chemotaxis and activation of white blood cells  Leukocytes follow chemical gradient to site of injury (chemotaxis) ♦ Bacterial products (esp. peptides with N-formylmethionine termini) ♦ Complement components (C5a) ♦ Cytokines (IL-8) ♦ Arachidonic acid metabolites (LTB4)  Chemotactic agents bind surface receptors inducing ic. Ca2+ mobilization and assembly of cytoskeletal contractile elements o Margination and rolling of white blood cells  Early rolling adhesion mediated by selectin family o Adhesion and transmigration of white blood cells o Phagocytosis and degranulation and/or leukocyte-induced tissue 57 injury  ACUTE INFLAMMATION DESTRUCTION The killing activity of neutrophils and macrophages is mediated via two main processes: ○ Oxygen-dependent killing (ROS) Stimulated by a powerful oxidative burst and enhanced by highly reactive compounds Phagocytosis triggers metabolic reactions (NADPH oxidase activity ↑) to produce oxygen metabolites: hydrogen peroxide H2O2, superoxide anion, hydroxyl radicals, hypochlorous acid and nitric oxide (NO) ○ Oxygen-independent killing See proteinases before 58  ACUTE INFLAMMATION DESTRUCTION Recognition / opsonization Phagosome formation Phagolysosome formation Bacterium opsonized (coated) by IgM, IgG, C3b and C4b Rubin, Strayer, Rubin: Rubin’s Pathology - 6th Edition 2012 binds to phagocyte (monocytes, macrophages, dendritic cells and neutrophil granulocytes) receptors (FcgR, CR1, 2, 3). Pseudopodes form around the microbe to enclose it within a phagosome. 59  ACUTE INFLAMMATION DESTRUCTION Efferocytosis: process by which dead and dying cells are removed by phagocytic cells 60  ACUTE INFLAMMATION DESTRUCTION Clearance of tissue debris and phagocytes (beneficial effect) Leukocyte-induced tissue injury (deleterious effect) ○ Destructive enzymes may enter extracellular space in the event of Premature (early) degranulation Frustrated phagocytosis (phagocyte fails to engulf its target, „toxic” agents are released into the environment) Membranolytic substances (urate crystals) Persistent leukocyte activation (rheumatoid arthritis, emphysema) 61  ACUTE INFLAMMATION TERMINATION I. Passive factors Elimination of initiating agent Dilution of pro-inflammatory factors Short half-life of inflammatory mediators (min) Apoptosis of PMN cells II. Active components Cytokine class switch - Gene reprogramming: supression of TNF-α, IL-6, IL-1ß genes; increased expression of IL-1RA, TNF-αR, IL-10 and other anti-inflammatory cytokines Lipid mediator class switch (ω-6 to ω-3 fatty acids): Lipoxins, resolvins, protectins, maresins↑ Protease inhibitors↑ Glucorticoids↑ (HPA axis): inhibits the transcription of pro-inflammatory genes in the nucleus, ↓PG production and neutrophil/macrophage migration Kininases↑: inactivate bradykinin TGF-ß: production is induced by apoptotic PMN – inhibition of pro-inflammatory cytokines; 62 stimulates production of lipoxins, resolvins & anti-inflammatory cytokines + fibrosis  ACUTE INFLAMMATION TERMINATION Serhan et al. Nat Rev Immunol. 2008; 8:349–361. 63  ACUTE INFLAMMATION SUMMARY Schwab & Serhan. Curr Opin Pharmacol. 2006; 6:414-20. 64 ACUTE INFLAMMATION OUTCOME Septic shock Sepsis 65  INFLAMMATION 2. 2023/2024 Prof. Dr. Zoltán Rakonczay, MD, PhD, DSc Professor and chairman Albert Szent-Györgyi Medical School Department of Pathophysiology Modified notes (from 2018) of Dr. Krisztina Csabafi and Prof. Dr. Gyula Szabó with contributions from Dr. Júlia Szakács, Dr. Miklós Jászberényi and Dr. Zsolt Bagosi Reviewed by Prof. Drs. Zsuzsanna Bata, László Kovács and Tibor Hortobágyi  INFLAMMATION 2: OVERVIEW Harmful inflammation Chronic inflammation ○ Basic concepts ○ Forms ○ Cellular involvement Systemic manifestations of inflammation ○ Acute phase response ○ Fever  Mechanisms, stages, patterns, consequences Pain ○ Terms ○ Processing pathways ○ Types  Nociceptive - Somatic - Visceral  Neuropathic - Central - Peripheral  Inflammatory - Primary hyperalgesia 2 - Secondary hyperalgesia  HARMFUL INFLAMMATION Rossi et al. Front. Immunol. 2021; 12:595722. Ineffective acute inflammation ○ Smoldering - chronic ○ Acceleration - systemic ○ Suppressed - compensatory anti-inflammatory response (cancer, sepsis) 3  CHRONIC INFLAMMATION BASC CONCEPTS Self perpetuating condition of prolonged duration that may develop in the course of recurrent or progressive acute inflammation or low grade irritants that fail to elicit an acute response Active inflammation (mononuclear cells), tissue destruction and repair (fibrosis) proceeding simultaneously May be localized, but more commonly progresses to disabling chronic disease (chronic restrictive lung disease, rheumatoid arthritis, asthma bronchiale, ulcerative colitis) Causes of chronic inflammation ○ Persistent injury or infection (ulcer, TB) ○ Repeated acute infection (rhinitis, otitis) ○ Prolonged toxic agent exposure (silicosis, atherosclerosis) ○ Autoimmune diseases, persisting antigens (rheumatoid arthritis, systemic lupus erythematosus [SLE], primary biliary cholangitis, 4 multiple sclerosis)  CHRONIC INFLAMMATION FEATURES RESEMBLING ACUTE INFLAMMATION Non-specific triggers: microbial products or injury Chemical mediators: direct recruitment, activation and interaction of inflammatory cells o Activation of coagulation and complement system generate small peptides to prolong the inflammatory response (IL-6 and CCL5 [RANTES] recruit mononuclear cells or IFN-α to promote macrophage proliferation and activation) o Inflammatory cells are recruited from blood; interaction between lymphocytes, macrophages, dendritic cells and fibroblasts generate antigen-specific response o Stromal cell activation and extracellular matrix remodeling, accummulation of connective tissue Symptoms: loss of function, pain 5  CHRONIC INFLAMMATION FORMS Nonspecific: diffuse accumulation of macrophages and lymphocytes at injury site (mononuclear phagocyte system) 6  CHRONIC INFLAMMATION FORMS Granulomatous: clusters of T cell-activated macrophages with epithelioid appearance often with T lymphocytes, which engulf and/or surround indigestible foreign bodies > can also cause injury to normal tissues o Immune-mediated granuloma (accummulation of macrophages surrounded by T lymphocytes and plasma cells) is due to infectious (M. tuberculosis, M. leprae, Treponema pallidum) or non-infectious (Crohn’s disease) cause o Foreign body granuloma (macrophages only) – talc, silica, suture 7 http://www.nature.com/ni/journal/v5/n8/images/ni0804-778-F1.jpg  CHRONIC INFLAMMATION CELLULAR INVOLVEMENT Cells are derived either from circulation (dendritic cells, macrophages, lymphocytes, plasma cells and granulocytes) or from affected tissues (fibroblast and vascular endothelial cells) Macrophages are the dominant cellular players Half-life of blood monocytes is about 1 day, whereas the life span of tissue macrophages is several months or years Antigen-presenting cells (APCs): protein antigen uptake and partial degradation; expression of HLA II, I and accessory molecules (e.g. CD80/CD86) for T-cell interaction & cytokine secretion ○ Monocytes & macrophages: phagocytose antigens and migrate to lymph nodes to present the antigen ○ Dendritic cells (e.g. Langerhans cells of the skin): minimal phagocytic activity, but efficient antigen presentation ○ B lymphocytes 8  CHRONIC INFLAMMATION CELLULAR INVOLVEMENT T and B lymphocytes ○ Antigen-activated (via antigen-presenting cells) ○ Release macrophage-activating cytokines (in turn, macrophages release lymphocyte-activating cytokines until inflammatory stimulus is removed) 1. T helper cells: IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-17, IL-23, interferon γ, colony stimulating factors, tumor necrosis factor-α 2. T cytotoxic cells: tumor necrosis factor-α, perforins 3. B cells: immunoglobulin Plasma cells ○ Terminally differentiated B cells; produce antibodies Granulocytes ○ Neutrophil granulocytes: in ongoing inflammation and tissue damage (emphysema, rheumatoid arthritis) ○ Eosinophil granulocytes: allergic (IgE-mediated) reactions and parasitic infestations Fibroblasts ○ Interact with lymphocytes (CD40 ligand) and both cells are activated. Activated fibroblasts produce EC matrix components, IL-6, IL-8, and PGE – tissue microenvironment in inflammation 9  CHRONIC INFLAMMATION MACROPHAGE-LYMPHOCYTE INTERACTIONS During inflammation, monocytes migrate from the blood stream into the tissue where they differentiate into macrophages. Depending on the type of stimulation, monocytes can either differentiate into M1 or M2 macrophages. M1 macrophages are mainly pro-inflammatory and cause tissue injury. In contrast, the main function of M2 macrophages is the inhibition of inflammation, they promote regeneration and fibrosis. In chronic inflammation M2 macrophages have a predominant role Chronic inflammatory reactions are sustained by the bidirectional M1 M2 interaction between macrophages and T helper cells. Activated macrophages present antigens to T lymphocytes and secrete cytokines (eg. IL-12) which stimulate T cells. Activated T- lymphocytes secrete IFN-y which activate macrophages, and TNF, Il-17 which act as chemokines, which will maintain the chronic inflammatory response. The activated macrophages and T- lymphocytes thus attract more inflammatory cells to the site and produce other inflammatory mediators as well. 10 Kumar, Abbas, Aster. Robbins Basic Pathology, 2018  CHRONIC INFLAMMATION METAINFLAMMATION Chronic overeating and obesity lead to low-grade systemic inflammation Mechanism o Overeating → cellular stress → macrophage polarization to M1 → pro-inflammatory cytokine production o Cytokines also influence metabolic functions → insulin resistance, Acosta-Martinez, Cabail. Int. J. Mol. Sci. 2022; atherosclerosis 23:15330.  CHRONIC INFLAMMATION SUMMARY Injury Vascular and cellular response Persistent stimulus Chronic inflammation Acute injury Activation of macrophages and lymphocytes Mild damage More severe injury Growth factors Cytokines Decreased metalloproteinase (PDGF, FGF, TGFß) (TNF, IL-1, IL-4, IL-13) activity Regeneration Repair Restitution of normal structure Scar tissue Fibroblast and endothelial Decreased collagen Increased collagen cell proliferation synthesis degradation Liver regeneration after Deep excisional wound partial hepatectomy Myocardial infarct Superficial skin wounds Fibrosis Resorption of exudate in lobar pneumonia Chronic inflammatory diseases: Liver cirrhosis, chronic pancreatitis, pulmonary fibrosis Chronic inflammation increases the susceptibility to malignant transformation! ECM components are essential for regeneration/repair: provide the framework for cell migration maintain the correct cell polarity for re-assembly participate in angiogenesis 12 EXAMPLES OF ACUTE AND CHRONIC INFLAMMATION 13 Kumar, Abbas, Aster. Robbins Basic Pathology, 2018  SYSTEMIC MANIFESTATIONS OF INFLAMMATION Acute phase response (APR) HPA axis activation: release of anti-inflammatory glucocorticoids from the adrenal cortex (loss of adrenal function → ↑severity of inflammation) Changes in leukocyte counts ○ Leukocytosis, leukemoid reaction - Neutrophilia: most bacterial infections - Lymphocytosis: mononucleosis, mumps, German measles - Eosinophilia: asthma, hay fever, parasitic infections ○ Leukopenia in chronic infection and advanced tumor, typhoid fever, and certain viral and rickettsial infections, SLE, Sjögren’s syndrome Sepsis: response of the body's immune system that results in organ dysfunction or failure Septic shock 14  SYSTEMIC MANIFESTATIONS OF INFLAMMATION ACUTE PHASE RESPONSE (APR) Systemic reactions in response to inflammation, infection, trauma, or malignancy in order to prevent ongoing tissue damage, isolate and destroy the infective organism and activate the repair processes necessary to restore the normal function Occurs within hours or days of onset of inflammation Induced by the production of cytokines such as IL-1ß (endogenous pyrogen), IL-6, tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ) and transforming growth factor β (TGF-β) 15  SYSTEMIC MANIFESTATIONS OF INFLAMMATION ACUTE PHASE RESPONSE (APR) 1. Fever 2. Leukocytosis: an increase in white blood cell numbers 3. Anorexia, somnolence, increased sleep and malaise 4. Increased heart rate and blood pressure, increased respiration, decreased sweating 5. Changes in the plasma concentrations of various acute-phase proteins (APPs) o Positive APPs (se level ↑) → Increase in erythrocyte sedimentation rate  Fibrinogen (blood clotting)  Mannose-binding protein (opsonization/complement activation)  Serum amyloid A (apoprotein)  C-reactive protein (opsonization/complement activation)  α-1 antitrypsin, α-2 macroglobulin (anti-proteinase)  Haptoglobin (Hb binding)  Hepcidin (iron homeostasis)  Ceruloplasmin (antioxidant, Cu binding) o Negative APPs (se level ↓)  Albumin, transferrin (and decreased iron levels in plasma → anemia), 16 insulin-like growth factor I SYSTEMIC MANIFESTATIONS OF INFLAMMATION ACUTE PHASE RESPONSE (APR) Changes in the plasma concentrations of various acute- phase proteins 17 SYSTEMIC MANIFESTATIONS OF INFLAMMATION ACUTE PHASE RESPONSE (APR) ↑ Metabolism in fat and muscle tissue leading to wasting ↑ Vascular permeability ↑ Prostaglandins and NO ↑ Cell adhesion molecules 18  HYPERINFLAMMATORY REACTION If homeostasis is not restored and the inflammatory stimuli continue to penetrate the bloodstream, a significant systemic reaction occurs Overactivation of the innate and adaptive immune system ‣ Activation of numerous humoral cascades Cytokine storm Direct tissue Formation of damage in various microthrombi organs Circulatory disturbance Dysfunction of the end organs Cytokines stimulate the release of tissue factor → activate thrombin and cause o coagulation o inflammation Cytokines inhibit the antithrombotic and fibrinolytic systems → promote coagulation 19  SYSTEMIC COMPLICATIONS OF INFLAMMATION SEPSIS, SEPTIC SHOCK Septic shock: sepsis with persisting hypotension requiring vasopressors to maintain a mean arterial pressure of ≥65 mmHg and a serum lactate level >2 mM/l despite adequate volume 20 resuscitation.  FEVER: AN ENDOGENOUS HEAT DISORDER Definition: elevation of body temperature that exceeds the normal daily variation (a.m. body temperature of > 37.2 °C or a p.m. temperature of > 37.7 °C orally) and occurs in conjunction with an increase in the hypothalamic set point o Mild fever: 37.5-39 oC o Moderate fever: 39.1-40 oC o High fever: 40.1-41 oC o Hyperpyrexia: above 41.1 oC Causes o Acute and chronic infections: bacteria, viruses, fungi, parasites (protozoa, helminths and ectoparasites) o Tumors: carcinoma of the pancreas, lung or bone, acute leukemias, lymphomas o Autoimmune diseases: SLE, rheumatoid arthritis o Vascular accidents (acute myocardial infarction, stroke), metabolic disorders (e.g. thyroid crisis) o Mechanical trauma causes tissue destruction o Drugs: sulfonamides, iodides, barbiturates, laxatives 21  FEVER OF UNKNOWN ORIGIN (FUO) Illness characterized by temperatures > 38.3 °C on several occasions for >3 weeks with no known cause despite an extensive workup Epidemiology o Infection (e.g. tuberculosis, HIV, Clostridium difficile enterocolitis, bacterial endocarditis) o Malignancy (e.g. malignant lymphoma, especially non- Hodgkin) o Autoimmune disease (e.g. Still's disease, temporal arteritis) o Noninfectious inflammatory disease (e.g. vasculitis) o Drug-induced (e.g. procainamide, penicillins, methyldopa, phenytoin) o Pulmonary embolism o Alcoholic hepatitis 22 o Other causes (e.g. inflammatory bowel diseases)  LOW GRADE FEVER Body temperature rises but does not exceeds the value of 37.5 oC Causes oHabitual hyperthermia: psychogenic fever in young females oHyperthyroidism oRheumatic fever oTuberculosis oExtensive cell lysis: hemolysis, neoplastic diseases 42  MECHANISMS OF FEVER GENESIS Exogenous pyrogens induce the release of endogenous pyrogens (IL-1, IL-6, IL-8; IFN-,, TNF-,) from leukocytes Endogenous pyrogens (circulating cytokines), via blood activation of the arachidonic acid cascade in the preoptic area of the anterior hypothalamus and the third cerebral ventricle release of PGE2 from the hypothalamic endothelium (primary capillary network of the organum vasculosum of lamina terminalis) stimulation of the 3rd receptor for PGE2 (EP3) on cells in the hypothalamic thermoregulatory center release of cAMP elevated set point heat conservation and production fever 43  MECHANISMS OF FEVER GENESIS Infectious agents Toxins FEVER Mediators of inflammations Monocytes/macrophages Endothelial cells Heat conservation Other cell types Heat production Elevated Pyrogenic cytokines thermoregulatory IL-1, TNF, IL-6, INF’s set point Anterior hypothalamus PGE2 Action of antipyretics 25  MECHANISMS OF FEVER GENESIS Vagal afferents transmit the pyrogenic signal to the hypothalamus, where they induce the release of norepinephrine and the activation of arachidonic acid cascade Direct activation of Toll–like receptors for microbial products (e.g. endotoxins), located on the hypothalamic endothelium PGE2 production and fever Local production by glial and neuronal cells of cytokines during a viral infection, CNS trauma or hemorrhage can also raise the hypothalamic set point and cause fever 26 MECHANISMS OF FEVER GENESIS 2) 46  STAGES OF FEVER 1. Stadium incrementi Core temperature rises to reach the new set point, heat production increased: cutaneous vasoconstriction, muscle activity increased, chills (goose bumps and shivering). The skin is pale, cold and dry. Shivering is an involuntary muscle activity when metabolic rate is increased 2-3 times the normal. 2. Stadium acmes (fastigium), plateau phase A balance between heat production and heat loss at a new set level. The skin is warm, flushed and dry. 3. Stadium decrementi The fever falls, the set level returns to normal, the body is too warm vasodilation and sweating Fever subsides by lysis/progressively or crisis/suddenly (sudden increase before it subsides – perturbatio epicritica) 28 STAGES OF FEVER 29  PATTERNS OF FEVER 1. Continuous or sustained fever (Febris continua continens) Sustained rise of the body temperature Diurnal variation < 1 oC In untreated typhus or typhoid 2. Remittent fever (Febris continua remittens) The temperature falls each day, but never to baseline Diurnal variation >1 oC Most common form of fever 3. Intermittent fever (Febris intermittens) The temperature is normal in the morning, rising during the afternoon Diurnal variation >1 oC, can reach normal values Pyogenic infections (abscesses), lymphomas, miliary tuberculosis, bacterial endocarditis Septic fever: a sharp rise and sharp fall in body temperature 30  PATTERNS OF FEVER 4. Periodic (recurrent) fever Recurrences of fever that last from a few days to a few weeks and are separated by symptom-free intervals of varying duration Can be caused by recurrent infection, malignancy or noninfectious inflammatory disorders (e.g. rheumatoid arthritis, Crohn’s disease) Types: Malaria: fever every 3rd day related to cyclic development of parasites Alternate day fever: Plasmodium vivax or ovale Rat bite fever – Streptobacillus, Spirillium minus Borrelia (Lyme disease, tick infection): erythema migrans, several episodes of high fever and afebrile periods (3-7 days), headaches, myalgia Undulant (Malta) fever – Brucellosis: Fever associated with anorexia, insomnia, headache, pain in the joints, bones and muscles, CNS symptoms Pel-Ebstein fever: infrequently seen in Hodgkin’s disease Bouts of high-grade fever and afebrile periods both lasting 7-10 days PATTERNS OF FEVER 51  CONSEQUENCES OF FEVER Increase in heart rate (8-12/min/oC) ○ Relative bradycardia: temperature-pulse dissociation, conditions where proportionate rise of pulse rate does not take place Typhoid fever, brucellosis, leptospirosis, some drug-associated fevers, and many factitious fevers Cardiac conduction abnormalities e.g. in acute rheumatic fever, viral myocarditis, bacterial endocarditis ○ Relative tachyarrhythmia: thyreotoxicosis, myocarditis Increase in respiration rate (2.5/min) Increase in metabolic rate (glucose, fat, protein catabolism) Increase in slow wave sleep Acute phase response (due to the effect of cytokines) ○ Hepatic synthesis of the acute phase proteins (e.g. C reactive protein - CRP, protease inhibitors, ceruloplasmin), fever, leukocytosis, increase in slow wave sleep, anemia, muscle cell proteolysis Increased host immune defense ○ T and B lymphocyte proliferation, neutrophil granulocyte chemotaxis and killing 52  DETRIMENTAL EFFECTS OF FEVER Discomfort due to general malaise Muscle wasting and weight loss Febrile convulsions – in some children, especially those with a family history of epilepsy Delirium due to hyperpyrexia sweating: loss of salt and water → dehydration Heart failure in elderly patients with cardiac disease Respiratory failure in patients with abnormal lung function Direct cellular damage (hyperpyrexia) 53 LOCAL SIGNS OF INFLAMMATION 35  PAIN An unpleasant sensory and emotional experience associated with actual or potential tissue damage Always subjective Threshold: point at which stimulus is perceived as pain o Varies minimally from person to person Tolerance: maximum level of pain that a person is able to tolerate before seeking relief o Varies from person to person: personality type, psychological state at onset of pain, past experiences, sociocultural background, meaning of pain o Increased tolerance: physical activity, warmth, cold, distraction, alcohol consumption, hypnosis o Decreased tolerance: repeated exposure, fatigue, sleep deprivation, anxiety, apprehension 36  PAIN TERMS Hyperesthesia: increased sensitivity to stimulation (includes both hyperalgesia and allodynia) Hyperalgesia: leftward shift in pain sensation – increased sensitivity to stimulation that normally provokes pain; light touch can be painful Allodynia: pain due to a stimulus which does not normally provoke pain Dysesthesia: an unpleasant sensation (throbbing, sharp), spontaneous or evoked Paresthesia: an abnormal sensation (tingling, itching), spontaneous or evoked Neuralgia: pain in the distribution of a nerve or nerves Neuropathic pain: pain caused by a lesion or disease of the somatosensory nervous system Phantom pain: perception of pain in the affected (amputated) limb. The neural pathway coming from an amputated limb is stimulated along its pathway, the impulse travels to the CNS and results in pain sensation 37  PAIN TYPES Duration o Acute: sudden onset, resolves after intervention or healing, associated with autonomic hyperactivity o Chronic: lasts >3-6 months; irritability, lack of energy and concentration, anxiety, insomnia, depression is frequent; peripheral or central sensitization Intensity: mild, moderate, severe Anatomic source: somatic (superficial or deep), visceral Etiology o Nociceptive (pain caused by tissue injury, somatic or visceral) o Neuropathic (central or peripheral) o Inflammatory o Dysfunctional (no identifiable noxious stimulus, no detectable inflammation or damage to the nervous system) o Mixed 38  PAINS TYPES Nociceptive (somatic and visceral) o Direct stimulation of peripheral nerve endings by noxious stimuli o Processing of brief noxious stimuli o Normal response to noxious insult or injury of tissues o Protective sensation (survival) with activation of pain pathway Neuropathic (peripheral and central) o Consequence of neurological damage o Spontaneous pain, greatly reduced pain threshold and mechanical allodynia o Lack of correlation between noxious stimuli and pain sensation o E.g. diabetic neuropathy, postherpetic neuralgia, spinal cord injury pain, phantom limb (post-amputation) pain, post-stroke central pain Inflammatory o Nociceptor sensitization due to inflammation (primary, secondary 39 hyperalgesia)  NOCICEPTIVE PAIN SOMATIC Involvement of mechano-, thermo -, chemo-, and polymodal nociceptors Superficial pain from cutaneous and subcutaneous tissues o Skin alone: tingling, sharp, cutting or burning o Vessels involved: throbbing pain Deep pain from muscles, tendons, ligaments, bones, joints and arteries: pain is more diffuse and tends to radiate to adjacent areas o Joint: well localized, sharp or burning o Bone: dull, aching or soreness o Muscle: dull ache or cramp 40  PAIN PROCESSING PATHWAYS  PAIN ASCENDING PATHWAYS 42  PAIN GATE CONTROL MECHANISM Physiological mechanism by which various factors can affect the experience of pain. Lamina II inhibitory opiatergic interneurons can be activated directly or indirectly (via excitatory interneurons) by stimulation of non-noxious large sensory Enkephalinergic interneuron afferents from the skin that would then block the projection neuron and therefore block the pain. Thus rubbing a painful area relieves the pain. Open gate Closed gate – Physical conditions – Physical conditions extent of injury medications, counter stimulation (e.g. heat, massage) – Emotional conditions – Emotional conditions anxiety or worry, tension, depression positive emotions, relaxation, rest – Mental conditions – Mental conditions focusing on pain, boredom intense concentration or distraction, 43 involvement and interest in life activities  PAIN DESCENDING PATHWAYS Periaqueductal gray matter (PAG) and Rostral ventromedial medulla (RVM) o An intrinsic or endogenous analgesia system o PAG is rich in opioid receptors and endogenous opioid peptides, administration of morphine into the PAG and surgical stimulation of PAG in intractable pain patients produces pain suppression (stimulus-induced analgesia) o PAG can modify the pain response of nociceptive cells in the spinal cord Nucleus raphe magnus (NRM) - serotonergic nucleus in the RVM o Activated by PAG, opioids o Serotonin (5HT) released activates interneurons which indirectly inhibit spinothalamic neurons Locus coeruleus (LC) o Releases norepinephrin, inhibits spinothalamic neurons and thus pain sensation 44  PAIN MODULATION  PAIN MODULATION At the site of injury, inflammatory response will be activated leading to extravasation of lymphocytes and other inflammatory cells. These cells will release inflammatory mediators including chemokines which can bind to chemokine receptors on the nociceptor terminal causing activation of the ion channels and adenylate cyclase which will increase the noxious signal and our perception of pain. Some inflammatory cells can also release opioids that can play a role in the modulation of pain by binding to their receptor on the peripheral nociceptive nerve terminal. The body has its own endogenous analgesic system, used to control, or inhibit the pain, mainly present in the PAG and nucleus raphe magnus in the RVM (descending pathways). PAG neurons in the midbrain release opioids when stimulated which will travel down to the RVM and activate serotonergic neurons in the nucleus raphe magnus. At the level of the dorsal horn of the spinal cord, these can act either directly on the ascending pathway neurons and inhibit the pain sensation, or indirectly via the local inhibitory interneurons. The local inhibitory interneurons release enkephalin that binds to opioid receptors of (1) first order neurons, where it inhibits the release of Substance P, CGRP, and glutamate thus decreasing transmission of impulses to the second order neurons or (2) second order neurons, where it indirectly activates K+ channels  K+ efflux leads to hyperpolarization of neurons  reduction of impulse transmission  less pain.  NOCICEPTIVE PAIN VISCERAL Involvement of distension sensitive nociceptors, lower density of other types of pain receptors Visceral pain is complex: diffuse, poorly localized, often referred to somatic regions (see referred pain) Severity of pain doesn’t always reflect the disease severity Develops due to internal organ dysfunction: abnormal stretching / flow obstruction → capsular/organ distension; spasm; traction or direct neural invasion of tumor; ischemia; inflammation Associated with strong emotional reactions: vagal & spinal activation of the anterior cingulate cortex Associated with exaggerated autonomic reactions: reflex spasm in abdominal wall (muscle guarding, defence musculaire), nausea, vomiting, sweating, blood pressure changes 47  PAIN REFERRED PAIN Pain originating from one site in body and perceived as being localized at a different site o Pain that is present in an area removed/distant from its point of origin o Often referred to dermatomes innervated by same segments of spinal cord as the painful organ o The area expressing the referred pain is supplied by the same spinal segment as the actual pain site Convergence-projection phenomenon o Two types of afferents enter DRG segment and converge onto same sensory projection cells o Brain doesn’t know actual source and projects to somatic site 48  PAIN REFERRED PAIN 49  NEUROPATHIC PAIN Lesion or disease of the somatosensory system Mechanisms: imbalances between excitatory/inhibitory somatosensory signaling → hyperexcitability o Alteration in ion channels and changes in second-order nociceptive neurons (activated by Aß, δ& C afferents; convey enhanced sensory information to the CNS [central sensitization: ↑NMDA/AMPA;loss of GABA-releasing interneurons]) o Impaired inhibitory modulation of pain messages in the CNS - Decrease in inhibitory interneuron activity in the brain: anxiety, depression, sleep problems - Defective descending pain-control system NA mediates conditioned pain modulation [CPM] (a painful stimulus inhibits another through descending pathways) CPM lost/damaged (NA inhibition↓; 5-HT↑) - Temporal summation ↑ (↑pain intensity upon repetitive identical nociceptive stimuli) due to central sensitization of ascending pain 50 pathways  NEUROPATHIC PAIN Central - Spinal cord injury (> 50% w pain), syringomyelia, demyelinization (multiple sclerosis) - Post stroke pain Peripheral (Aß, δ & C fibers affected) - Trigeminal (facial, intra-oral trigeminal territory), postherpetic (one/more dermatomes or ophthalmic trigeminal division [r. ophthalmicus]), ilioinguinal, genitofemoral neuralgia - Infra- & supraorbital, occipital, intercostal, brachial, ulnar, femoral neuritis - Painful diabetic, HIV-associated, chemotherapy-related polyneuropathy („glove and stocking” pain) - Meralgia paresthetica: damage to the lateral femoral nerve - Cervical, lumbar radiculopathy (innervation territory of the affected nerve root) - Carpal tunnel syndrome (median nerve compression) - Neuroma 51  PAIN COMPARISON OF NOCICEPTIVE AND NEUROPATHIC PAIN 52  INFLAMMATORY PAIN Inflammation can cause nociceptor sensitization (primary and secondary hyperalgesia); activation of previously unresponsive receptors and heightened central nervous system response Hyperalgesia ○ Leftward shift in pain sensation – increased sensitivity to stimulation; light touch can be painful ○ Forms Primary Secondary 53  INFLAMMATORY PAIN PRIMARY HYPERALGESIA Increased pain sensitivity at the site of injury due to nociceptor sensitization (by chemicals released from damaged tissue) Nociceptors: connected to Aδ and C fibers Possible mediators o K+ and histamine released by damaged cells o Serotonin (from platelets) o Bradykinin – one of the most potent o Prostaglandins o Leukotrienes o Substance-P 54  INFLAMMATORY PAIN SECONDARY HYPERALGESIA Increased sensitivity to pain in areas adjacent or distant from injury when a noxious stimulus is delivered to a region surrounding, but not including, the zone of injury o Injury to arm → pain in the arm o Bladder inflammation → pain in the abdominal / pelvic region Stimulation of mechanoreceptors (Aß-afferents) can induce pain Due to central neuron sensitization, requires continuous nociceptor input from the zone of primary hyperalgesia for its maintenance Thermal hyperalgesia does not occur in the secondary zone 55  PAIN Sinatra et al. Acute Pain Management. Cambridge University Press, 2009. 56  IMMUNOLOGY 1. Prof. Dr. Zoltán Rakonczay, MD, PhD, DSc Dr. Krisztina Csabafi, MD, PhD Dr. Miklós Jászberényi, MD, PhD, DSc Albert Szent-Györgyi Medical School Department of Pathophysiology 2024 Modified notes (from 2018) of Prof. Dr. Gyula Szabó.  IMMUNOLOGY 1: OVERVIEW Structure of the immune system Basic principles Hypersensitivity reactions ○ Antibody / immunoglobulin-mediated  Type I / immediate / anaphylactic reaction  Type II / cytotoxic reaction  Type III / immune complex mediated reaction ○ Cell-mediated  Type IV / delayed / late-phase reaction Autoimmune diseases ○ Organ-specific  Basedow-Graves’ disease, Hashimoto thyreoidits, T1DM, myasthenia gravis, vitiligo, allopecia areata, psoriasis, atrophic gastritis, celiac disease, multiple sclerosis ○ Systemic  Sjögren’s syndrome, autoimmune polyendocrinopathies, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis, acute rheumatic fever 2 STRUCTURE OF THE IMMUNE SYSTEM https://www.creative-diagnostics.com/innate-and-adaptive-immunity.htm 3 COMPARISON OF THE INNATE AND ADAPTIVE IMMUNE SYSTEMS Characteristics Innate (non-specific) Adaptive (specific) Specificity For molecules shared by For microbial and groups of related microbes nonmicrobial antigens and molecules produced by damaged host cells Diversity Limited; germline encoded Very large; receptors are produced by somatic recombination of gene segments Memory None Yes Non-reactivity to self Yes Yes Components Cellular and chemical Skin, mucosal epithelia; Lymphocytes in epithelia; barriers antimicrobial molecules antibodies secreted at epithelial surfaces Blood proteins Complement, plasma Antibodies contact activation system Cells Phagocytes (macrophages, Lymphocytes neutrophils), natural killer cells, innate lymphoid cells 4 5 DIFFERENTIATION OF LYMPHOID CELLS Minority of human B cells arising from a fetal stem cell with self renewing capability and little immunological memory; CLL is 10% IgM >> IgG often B1 origin, autoantibodies: elderly, females Conventional B cells, produced after birth & replaced from the bone marrow w immunological IgG > IgM memory;  TCR CD4+ & CD8+ 2:1 ratio 80% Initial response to bacterial antigens presented in mucosal epithelium Recognizes glycolipids without HLA presentation NK/ILC Lymphoid morphology [cells NK/ILCs 10% without cell lineage marker (Lin-)] Lack of antigen receptors 6  ANTIBODY-MEDIATED ADAPTIVE IMMUNE RESPONSES: B-2 B LYMPHOCYTES IFN-g IL-4 HLA molecules CD4+ T helper cells CD40 Ligand 7 8  TH CELL DIFFERENTIATION FROM NAIVE CD4 T CELLS Th1 cells produce IFN-γ and are involved in cell-mediated immunity against intracellular bacteria and viruses. Th2 cells are important in humoral immunity against parasites through their production of IL-4, IL-5 and IL-13. Th17 cells play a critical role in host protection against extracellular pathogens and in inflammatory autoimmune diseases. Treg cells, which produce TGF and IL-10 and act as modulators of immune responses. Allergy APC: antigen-presenting cell, Foxp31: forkhead box p31, IFN: interferon, MHC– TCR: major histocompatibility complex– T-cell receptor, ROR: retinoid-related orphan receptor, TGF: transforming Autoimmunity growth factor, Th: T helper, Treg: regulatory T. STAT: signal transducer and activator of transcription Cell Mol Immunol. 2010 May; 7(3): 182–189. 9  BASIC PRINCIPLES OF IMMUNE REGULATION 1. During embryonic development a total number of 1011-1014 different B and T-cell clones are generated by somatic recombinations with the help of RAG1, RAG2 (Recombination-activating gene proteins) and TdT (Terminal deoxynucleotidyl transferase). 2. In the immature immune system negative selection prevails. Binding to self- antigens evokes apoptotic clonal deletion. Therefore, due to central and peripheral tolerance the number of reactive clones falls to approximately 106. 3. However, due to somatic hypermutations brought about by activation-induced cytidine deaminase (AID) these clones can further adapt to the stimulating antigen. 4. In the mature immune system reactive clones respond to stimulus with proliferation. Maturation and complete switch in the nature of the immune reaction requires transient protection of infant immunity by breast-feeding. 5. Estrogen and prolactin activates the immune system while hCG, progesteron and androgens inhibit it. 10  GENERAL OVERVIEW OF SOMATIC OR V(D)J RECOMBINATIONS https://medicine.yale.edu/keck/ycga/sequencing/10x/singcellsequencing/ 11 CENTRAL AND PERIPHERAL TOLERANCE MECHANISMS IN THE ADAPTIVE IMMUNE SYSTEM Selection against self-reactivity in developing T cells occurs in the thymus, where more than 98% of developing thymocytes die from apoptosis because of excessive reactivity to self-peptides bound to major histocompatibility complex (MHC) molecules, followed by positive selection for functionally competent effector T cells (CD4+ and CD8+) that are released into the periphery. The expression of self- antigens in the thymus is genetically regulated by transcription factors, such as autoimmune regulator, or by genetic variation in self-antigens themselves (e.g., insulin). The production of peripheral regulatory T cells (Tregs) is also under genetic control, exemplified by the transcription factor FOXP3, the absence of which leads to severe autoimmunity. Peripheral mechanisms for preventing self-reactivity also exist. In this context, Tregs play a key role in T cells, where genetic alterations in interleukin-2 pathways may influence the efficiency of Treg regulation. 12  BASIC PRINCIPLES OF IMMUNE SYSTEM 1. Antigen: Any substance that is identified by the immune system as foreign that causes the body to make an immune response against that substance. 2. Epitope (antigenic determinant): the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells or T cells. 3. Hapten: Small molecule that alone can not elicit an immune response. However, binding to a large carrier protein it can lead to the formation of neoantigen and initiate the immune response. 4. Antigenic mimicry: During evolution microbes altered their antigen