Inflammation and Tissue Repair

Inflammation and Tissue Repair

• Inflammation is a protective response in vascularized tissue.
• Acute inflammation is caused by infections, tissue necrosis, hypoxia, foreign bodies, and hypersensitivity reactions.
• Acute inflammation features heat, pain, redness, swelling, and altered function (calor, dolor, rubor, tumor, and loss of function).

Components of Acute Inflammation

• Vascular changes involve smooth muscle dilation and increased endothelial permeability.
• Cellular events include neutrophil emigration, metabolic activation, chemotactic migration to the injury site, and phagocytosis of microbes or damaged tissue.
• Transudate is fluid pushed through the vessel wall due to increased intravascular hydrostatic pressure, resulting in excess extravascular fluid.
• Increased vascular permeability occurs in acute inflammation.
• Exudate is the leakage of protein-rich fluid, large molecules, and cells into surrounding tissue due to increased vascular permeability.

Functions of Transudates and Exudates

• They dilute toxins from dead cells
• They limit use of area preventing additional injury
• They carry blood cells and proteins to the site (antibodies and complement).
• They carry toxins and wastes from the site primarily through the lymphatic system

Mechanisms of Increased Permeability

• Endothelial cell contraction: Histamine, bradykinin, and leukotrienes cause rapid response.
• Endothelial retraction: Widened intercellular gaps in post-capillary venules occur.
• Direct endothelial injury: Immediate and sustained leakage

Leukocyte-Mediated Injury

• Activated leukocytes release toxic substances damaging endothelium.

General Sequence of Cellular Events

• Selectins (early rolling phase) mediate weak adhesion.
• Integrins (firm adhesion phase) prepare cells for migration.
• Adhesion molecules (diapedesis and migration phase), like ICAMs, help leukocytes squeeze between endothelial cells and enter tissues to regulate transendothelial migration.
• Neutrophils accumulate at sites of acute inflammation early.
• Neutrophils replaced by macrophages over time.
• Leukocytes move unidirectionally up a chemical gradient toward the injury site.
• Chemical factors bind cell surface receptors, inducing a series of metabolic changes called leukocyte activation.
• Leukocyte phagocytosis engulfs cell debris, microbes, and foreign material. Neutrophils, monocytes, and macrophages are the primary phagocytes.
• Bacterial killing occurs via reactive oxygen species formed in phagolysosomes, leading to increased O2 consumption via NADPH oxidase converting O2 to superoxide.

Microbial Killing and Degradation

• Superoxide dismutates to H2O2.
• Lysosomal myeloperoxidase uses Cl- + H2O2 to create HOCl free radical.
• Most deficient bactericidal system, killing bacteria by halogenation or protein/lipid peroxidation, then degraded by lysosomal acid hydrolases

Microbial Killing and Degradation (Non-Oxygen Dependent)

• Bacterial permeability-increasing protein exists
• Lysozyme degrades bacterial coat oligosaccharides
• Arginine-rich cationic peptides kill microbes by creating holes in membranes
• Major basic protein produced by eosinophils is cytotoxic to parasites
• Leukocytes secrete granule components to destroy extracellular microbes

Defects in Leukocyte Function

• Defects lead to increased susceptibility to infection
• Defects in leukocyte function result in increased susceptibility to infection and are the most common cause of defective inflammation

Chemical Mediators of Inflammation

• Vasoactive amines include histamine (vasodilation) and serotonin (vasoconstriction during clotting).
• Arachidonic acid metabolites include prostaglandins, leukotrienes, and lipoxins, which inhibit inflammation, PMN chemotaxis, and adhesion to endothelium.
• Cytokines and chemokines include TNF, IL-1, and IL06
• Reactive oxygen species aid in killing ingested microorganisms
• Nitric oxide causes vasodilation and inhibits platelet aggregation.
• Lysosomal constituents include enzymes and bactericidal factors, which are potential mediators of inflammation and tissue destruction, released during phagocytosis.
• Plasma proteases: C3a and C5a anaphylatoxins, C3B opsonin enhance phagocytosis, C5-9 membrane attack complex
• Neuropeptides: Substance P, neurokinin A help to initiate the inflammatory response

Chronic Inflammation

• Chronic inflammation lasts for a prolonged duration
• Macrophages are the dominant cells in chronic inflammation
• Classical macrophage activation is induced by bacterial LPS, foreign material, and interferon-y secreted by T cells, increasing inflammatory response
• Alternative macrophage activation is induced by cytokines like IL-4 and II-13 produced by Th2 cells, mast cells, and eosinophils
• Chronic inflammatory cells include B and T lymphocytes, and CD4+ cells including Th1, Th2, and Th17
• Eosinophils are found in parasitic infections and immune reactions mediated by IgE
• Mast cells are widely found throughout connective tissue, respond to stimuli, are important in acute and chronic inflammation
• Neutrophils are bigger in acute inflammation but can still be seen in chronic inflammation

Granulomatous Inflammation

• Granulomatous inflammation is a type of chronic inflammation
• Multinucleated giant cells may be present
• It can be noncaseating or caseating
• Causes include bacterial, parasitic, fungal, inorganic, metal, dusts, foreign body, or unknown agents
• Granulomas may not always eradicate the entire offending agent

Tissue Repair

• Regeneration replaces cells with the same type of cells
• Replacement with connective tissue (scarring) occurs when there is no regeneration or when the connective tissue matrix is extensively damaged.

Labile Tissues

• Labile tissues are composed of continually dividing stem cell populations that replace lost cells, and can readily regenerate after injury as long as the steam cell pool remains
• Bone marrow, most surface epithelia such as skin and oral cavity, gastrointestinal tract, and urinary tract

Stable Tissues

• Stable tissues are quiescent with cells in G0 that have a normal, low level of replication but can activate rapidly by re-entering G1
• Liver has limited capacity to regenerate

Permanent Tissues

• Permanent tissues are composed of terminally differentiated cells that cannot proliferate postnatally
• Nerve cells and skeletal and cardiac muscle cannot regenerate well, so repair relies on scarring

Repair by Scarring

• Repair by scarring occurs when damage to parenchyma and connective tissue is extensive in chronic inflammation, or when permanent tissues are damaged and regeneration alone cannot repair damage
• Scarring involves formation of new blood vessels, migration and proliferation of fibroblasts, deposition of new ECM by fibroblasts, and maturation and organization (remodeling) of the ECM to form a scar, and results in granulation tissue
• TGF-B is important in increasing collagen for scar formation
• Myofibroblasts are involved in wound contraction
• Wound strength varies for sutured wounds and final skin wound strength is about 70-80% original after suture removal
• Factors affecting wound healing include nutrition, circulatory status, hormones, and local infection

Introduction to Pathology: Cellular Injury

• Cellular injury is fundamental to disease pathology
• Understanding injury mechanisms helps identify disease causes and consequences
• Injury severity depends on cell type, insult type, damage degree, and reversibility

Internal Causes of Cell Injury

• Water damage: DNA hydrolysis can lead to mutations
• Oxygen damage: Free radicals (OH-) cause DNA modifications, strand breaks, and oxidative stress
• Methylation changes in DNA methylation can influence gene expression and promote mutation
• Unrepaired DNA damage: Leads to mutations, cancer, or death

External Causes of Cell Injury

• Free radicals cause excitotoxicity where glutamate induces reactive oxygen species
• Free radicals cause Ischemia/reperfusion jury
• Free radicals cause receptor agonist glycosylated and products stimulation in neurons and endothelial cells
• Free radicals cause RAGE stimulate is cultured neuroblasts by B-amyloid
• Free radicals are produced by neutrophils and macrophages and cause base damage strand breaks in DNA, productions of crosslinks in proteins, and membrane per oxidation of lipids causes rearrangements of molecular structrues
• Physical agents such as trauma, radiation, extreme temperatures, and electric shock
• Chemical agents like mercury, lead, and drugs can cause direct or metabolically activated injury
• Infectious agents such as bacteria, viruses, fungi, and prions,
• Autoimmune diseases caused by self-attack by the immune system by T or B lymphocytes,
• Gaining can cause telomere shortening, DNA errors, and cumulative damage

Other Causes of Cell Injuries

• Hypoxia from reduced oxygenation exists.
• Ischemia from reduced blood flow due to vessel blockage results in myocardial infarcts and strokes
• Reduced oxygenation with normal blood flow caused by pulmonary disease, anemia, and CO poisoning

Factors Affecting Cellular Responses

• Factors affecting cellular responses include metabolic rate, presence of specific viral receptors, nutritional state of the host, metabolism of an inert compound to a toxic agent, metabolic states of the host, and idiosyncratic factors

Cell Injury Mechanisms

• Damage to cell membranes and subcellular organelles

Cell Injury

• ATP depletion causes decreased phospholipid synthesis
• Degradation of membranes by Calcium activated phospholipase A2 and proteases exists
• Lipid peroxidation occurs by free radicals
• Detachment of membranes from protease-damaged cytoskeleton

Cell Injury and Death

• Cell injury can lead to programmed suicide (apoptosis), which involves the release of cytochrome c
• Cell injury and necrosis (reversible, non-lethal injury) can occur

Cell Injury Morphology

• Reversible injury involves fat accumulation in hepatocytes and cardiac myocytes, usually found in hypoxia and chemical exposure
• Intracellular accumulations include cholesterol, lipofuscin, and iron (hemosiderin, hemosiderosis, hemochromatosis)
• Bilirubin accumulation is seen in jaundice
• Carbon deposits like anthracosis can accumulate in lung macrophages within coal workers
• Calcium deposits, such as dystrophic calcification, occur in damaged tissues and metastatic calcification results from high calcium levels
• Coronary artery calcifications from plaque buildup lead to cardiovascular disease

Cellular Adaptation

• Understanding how cells respond to injuries is crucial for understanding disease mechanisms.
• Homeostasis: Factors influencing cellular responses include the type, degree, and duration of alteration, as well as the affected cell type.

Types of Adaptations

• Increases include regeneration (replacement of losses by cellular multiplication), hyperplasia (increase in cell number), and hypertrophy (increase in cell size)
• Decreases include hypoplasia (decreased cell number), atrophy (decreased cell size), and involution (loss of cellular content, often via apoptosis)
• Changes include modulation (phenotypic modification), metaplasia (replacement with another cell type), neoplasia (cancerous transformation), and subcellular adaptations (adaptation of intracellular organelles)

Causes of Hypertrophy

• Hypertrophy is caused by increased functional demand, endocrine stimulation, hormones, local mitogens, increased nutrition, increased blood flow, mechanical factors, pharmacological agents, or imbalance between anabolism and catabolism

Causes of Hyperplasia

• Hyperplasia results from stimulation of target tissues by hormones or growth factors such as puberty, menstrual cycle, or pregnancy, but can be a precursor for cancer if prolonged.
• Grave's disease affects the thyroid gland, causing enlargement (goiter) and asymmetrically enlarged glands

Atrophy and Involution

• Atrophy means decreased cell size and diminished functional capability without cell death, reducing the size and capacity of the affected organ - Atrophy can be due to hunger or pressure
• Involution involves a decrease in cell number via apoptosis, resulting in decreased size and function of the affected organ, occurs in thymus and is common in hormone withdrawal

Metaplasia

• Metaplasia involves replacement of one type of differentiated cell by another from the same germ layer, such as squamous metaplasia in the respiratory tract of smokers
• Deficiency is a loss of protection conferred by mucous secretions and ciliary removal of particulate matter

Tissue Repair

• Tissue repair from injury involves regeneration (dependent on proliferative capacity) or connective tissue formation (scar)
• Regeneration is driven by cytokines, growth factors, and cellular interactions with the extracellular matrix

Cell Death Types

• Necrosis is uncontrolled cell death with inflammation. It involves cell swelling, cellular organelle swelling, leakage of cellular contents, and inflammation in surrounding tissue caused by outside factors, and is always abnormal
• Apoptosis is programmed cell death without inflammation. It involves cell shrinkage, chromatin condensation, formation of cytoplasmic blebs, induction of apoptosis by p53 protein, release of cytochrome C, cell breakage into small fragments, and phagocytosis without inflammation, the cell kills itself, and is sometimes normal in development
• Necroptosis is a hybrid of necrosis and apoptosis relevant in neurodegeneration
• Pyroptosis : cell death that induces inflammation. Includes fever production.
• Anoikis is a programmed cell death occurring upon cell detachment from the correct extracellular matrix thus disrupting intergrin ligation.

Types of Necrosis

• Coagulative necrosis is typical in cell death resulting from ischemia/hypoxia
• Liquefactive necrosis is typical of CNS infarctions and bacterial infections
• Caseous necrosis has a cheesy macroscopic appearance
• Fat necrosis exists in gangrene infarction of extremities

Necrotic Changes and Dysregulated Apoptosis

• Necrotic changes are associated with dead cells in living tissues from protein denaturation and enzymatic digestion with fading of stainable chromatin and nuclear condensation or fragmentation
• Inhibited apoptosis is linked to cancer and autoimmune diseases
• Excessive apoptosis is seen in neurodegeneration, viral infections, and ischemic injuries
• Death receptor domains are targets for apoptosis regulation in cancer therapy, which also uses regulators of the external pathway and bcl-2 inhibitors in the treatment of B-cell lymphomas

Bacterial Structure

• 16S rRNA phylogeny classifies bacteria based on evolutionary relationships
• Dendrograms show relatedness among bacterial species
• The three domains include bacteria, archaea, and eukaryote
• Bacterial classification includes kingdom, phylum, class, order, family, genus, and species The bacterial cell wall is made up of peptidoglycan, which provides shape and prevents lysis.
• There's crosslinking between the 4th D-ala and the 3rd amino acid directly or via a multi-amino acid bridge which adds strength to peptidoglycan
• Gram staining differentiates bacteria by cell wall structure
• Gram-positive bacteria have a thick peptidoglycan layer and an inner cytoplasmic membrane
• Gram-negative bacteria have an outer membrane, a thin peptidoglycan layer, and an inner (cytoplasmic) membrane

Gram-Stain Steps

• Gram-positive bacteria stain purple with crystal violet trapped inside the cell wall
• Gram-negative bacteria stain red with safranin
• Ethanol collapses peptidoglycan and extracts lipids from the outer membrane

Bacterial Cell Wall Differences

• Mycoplasmas lack a cell wall
• Cell wall defective bacteria include CWD(Cell wall deficient bacteria), defective (changes or partial loss of the cell wall) and L-form (no cell wall)
• Teichoic acids and cell wall-anchored proteins give the cell wall a negative charge

Peptidoglycan Biosynthesis

• NAM is synthesized from NAG
• The pentapeptide chain attaches
• Undecaprenyl carrier transfers the NAG-NAM pentapeptide subunit to the outer membrane
• Crosslinking is done by penicillin-binding proteins

Antibiotics Targeting Peptidoglycan

• Vancomycin binds D-Ala D-Ala which blocks insertion of subunits by penicillin-binding proteins
• β-lactams directly bind and inhibit penicillin-binding proteins
• Phosphonomycin/Fosfomycin block NAM synthesis
• Bacitracin blocks carrier recycling
• D-cycloserine blocks addition of D-AIA

Bacterial Membranes

• Bacterial membranes are made of phospholipids
• Gram-positive membrane structure has lipoproteins, lipoteichoic acid, and membrane proteins
• Gram-negative structure has an inner and outer membrane with LPS that can cause septic shock

Additional Bacterial Structures

• Porins bring substances in and out of cells
• Capsules protect bacteria from phagocytosis and drying
• Matrix protects bacteria with biofilms and slime layers
• Pilli/fimbriae are for attachment, DNA transfer, and movement
• Flagella are composed of flagellin and are powered by a proton-motive force for motility
• Bacteria do not have a nucleus of organelle, their DNA is compacted to fit in the bacertial cell
• Gyrase and topoisomerase V allow for DNA replication
• Bacteria also have extrachromosomal plasmids, circular similar to the chromosome that contain virulence and antibiotic resistant factor

Bacterial Metabolism

• Bacteria live in multispecies biofilms in microbiota, where diverse bacterial metabolism supports microbiota ecology
• They convert glucose to pyruvate using the Embden-Meyerhof-Parnas pathway
• This process consumes ATP and phosphate and produces 4 ATP oxidized by pyruvate reduction (fermentation/oxidation) or the electron transport system (respiration)
• Metabolism of dietary sugars causes drop in pH as they are metabolized.

Sugars and Fermentation

• Sugars enter glycolysis at Fructose-1,6-diphosphate ( a rate-limiting step)
• Fermentation of pyruvate occurs when bacteria reduce pyruvate to recycle NADH+ H+
• End products of fermentation are acids (short-chain fatty acids), alcohols, diols, and gases
• Types of substrates used, the types of endproducts and regulation of the pathways involved that can vary between species
• SCFA specifically acetate, proportionate, and butyrate have an infleunces on the human host
• Acetate, proprionate, and butyrate can enter human metabolic pathways and act as signals at distal body sites
• Microbiota affects short-chain fatty acids, molecules, and bile acid metabolism
• dietary sugars causes drop in pH as they are metabolized.
• S. mutans use numerous dietary sugars, fermenting them to produce lactic acid. They can store excess sugars as intracellular polysaccharide and metabolize them after depletion of dietary sugars.
• S. mutans is fund in dental plaque. Lactic acid produced by fermentation lowers pH and dissolves enamel (demineralization).
• Xylitol can be transported into S. Mutans using fructose phosphotransferase system, is toxic to S. mutans, and cause cell death
• Electrons from respiration go through the Krebs cycle and an electron transport chain for generation of proton motive force oxidative phosphorylation to produce ATP.

Additional Metabolsim Facts

• Bacteria have no organelles, so the ETC is of cellular membrane, and a single bacteria can use multiple pathways depending on environmental conditions
• Requirements for bacteria growth are energy and a carbon source
• Microbiota organisms can be auxotrophic.
• Some microbiota organisms can be auxotrophic , they cannot synthesize particular compounds required for growth and do iron scavenging using siderophores

Bacteria Harm

• Lysis of red blood cells allows for iron scavenging
• Metabolic cooperation and cell signaling depend on location of biofilm
• Pathogens can invade microbiota; cause inflammation

Bacterial Genetics

• Bacteria have genomic flexibility from single nucleotide polymorphisms (SNPs) or genetic content in mobile genetic elements
• Bacteria are haploid
• Genetic mutations are random and can be due to error-prone polymerases

Horizontal Gene Transfer

• Horizontal gene transfer allows bacteria to acquire new traits including antibiotic resistance and virulence factors.
• Transformation allows uptake of free DNA from dead bacteria. The bacteria must be competent and be able to incorporated via homologous recombination so it relies on recA dependent.
• Conjugation allows transfer of plasmids from bacteria via a pilus. F-plasmid conjugation can also involve integration into the chromosome that allows larger pieces of bacterial DNA to be transferred or incorrectly excise, carrying chromosomal DNA.
• Transduction: bacteriophages transfer bacterial genes. Generalized - a phage randomly packages bacterial DNA instead of single strand or RecA involved
• Specialized transduction:
• Transposons- move within genome causing genetic changes, does not require homologous recombination
• What you add DNase to interfere with is transformation since it doesn't require cell to cell transfer

Horizontal Gene Transfer

• occurs between two already existing organisms.
• transduction and transformation
• Transformation – of genetic material. Called competence to take up free DNA
• foreign genetic material introduced via bacteria
• cell to cell contact of two bacteria

Defense Againtst Bacteria

• Pathogenicity islands are large genomic regions containing virulence genes
• CRISPR- system: Prevents horizontal transfer, Prevents insertion of foreign DNA, Limits acquisition of mobile elements.

Bacterial Growth

Bacterial Growth and Dental Plaque Formation

• Bacterial growth phases are lag phase, log phase, stationary phase, and death or decline phase
• Binary fission is bacteria's main way to replicate
• Fragmentation/budding are alternative
• Doubling time are physical parameter

Oxygen Growth Conditions

• Anaerobes grow only in the absence of oxygen. Obligate anaerobes are killed by O2, while aerotolerant anaerobes can withstand O2. Microaerophilic anaerobes prefer reduced O2 tension
• Aerobes and facultative growths dependent upon oxygen
• Bacteria need formation of peptide bonds, Bacterual translation to groing and start

Biofilms

• Metabolic cooperativity and cell-cell signaling are important for biofilm formation
• Primary colonizers attach to pellicle which includes S. Mutans. which lead to cavities Then bridge formation occurs with fusobacterium. Then late colonizers come like those involved w/ gingivititis, peridontitis
• Coryebacterium plays a role in early colonization Is not a primary colonizer An actinomyces has structure to help tooth
• Use 16s genearray to identify, Also can use the other

Additional Structures

• Healthy diet important to prevent
• Antimicrosal therepay= microbes good in the right place: they are bad in the wrong places Enviromental,Commuinity acquired, Nosocomial (hospital accuired) more resistence.

Antibiotic Therapy Types

• Empirical something quickly.
• Definitive – select drug to kill
• Prophylactic- taking to prevent

Classification of Anitbiotics

• Action of anitbiotics
• beta lactrams-penecilin related (cephalo, corba,mono)

Actions of Anitmicrobial Drugs

• Very selective (insoniazidd) broad (PENcilin) Antimicrobials either disrupt cell wall/ membrane or inhibit protein synthesis Cell wall membrane integrity can develop resistant no permeante can happen after

Combinations

• Want to be synergistic when comboing
• Potetiaition- make one drug better. No effeect but enhances

Antibiotic Info

• Restrict-baceriotstatic- restcing growth and
• Baccertiodial causing death

Bacterial Resistance

• 4X is resistant with bactertioatic drugs
• When bacertidal concentration with less then 4

Factors

• Broad and narrow
• Definitive treatment 4 antibiotics Adverse: -alergie ,diarhea , liver failure -Toxicity

Resistance Mechanisms

• Alter pathway
• Mutation to acquire DNA
• Beta-lactam – destroys beta
• Cephlasporin 4 classes

Bacterial Treatment

• Disrupt cell wall
• Glycopeptides-bind to dal-DLA . INhibiot protein synthes- 50 and subunits- azithros- erythromycin
• Penicillin= effective against great activity,
• adverse- hypersenisty- gi issued penicelin types broad, anit
• Inhibitors with clavulanic, tazobucatam - these help treat antibiotic penecilian-

Cephalosporin:

• Similar to penicillin structure
• Less septable
• All different generation. Each generate has its own use
• • adverse- phelbitits at injecction

Carbupenem

• All end in- penem
• Side effect g1 diease

Monbactuam actureon

• Azteoreonam-
• Treats gram-

Treat URes and Res issues Skin and pseudos

Clostridiums and anaerobes

• 3 pathogens c.perfreige and others
• produce toxins

C tetnai

• causes cell
• has vaccine

Bacilius

• Anthrax
• Cereus cause GI ditress

Antibiotics and Resistance Mechanisms

• MIC- lowest concentration inhibiting growth of bacteria
• All antibiotics have minimal inhibitory concentration
• Only bactericidal kill bacterial concentration

Antibiotic Notes

• Antibiotic resistance is dependent on
• Resistant bacteria may be able to be inhibited by very high concentrations of antibiotics not achievable in patients
• Bacteria can either be resistant have a or clinical close to be resistant or bacterial sensitive
• Antibiotic resistance: Natural (insteresic): Natural property that affect This is done through other type I pumps or protections Vertical and horizontal spread Acquired The first few intersect And is reversible

Antibiotic Treatment

• Random chromosome
• Combinations with mutation horizontal with antibiotics

More Antibacterial Notes

Active antibiotics

• Binds Antibiotics more Antibiotics more harmful antibiotics Antibiotic can be

Antibacterial:

Disrupt the process Treat upper or lower The side effects

Glycopeptide and Vancomycin

Disrupts membraine has negative impact Most bacteria will be disrupted so bacteria will be disrupted: Antibiotics that have issues with the heart

Cell Wall and Membrane Integrity

Most antibiotics effects with cell membrane: Use polyl peptide will have side effects Use in combination 1+ and bacteria

Protien Treatments and Drugs

• All have gl but less has adverse effects

• Binf dinto bactrial rna polymerase non ribosome

• Clindmnyic = gram + . used acne

• Amino glucose: infections or nephrocity.. blocks

Anitiboitcs facts

• Sulfa with stevoen sydrome reaction
• metral-anarobia

Periodontal

• Gingiva the process Clean the bacteria to prvent buildup and biofilm Barries that prvent and protect infection and damage with epitelium and all the other things

Periodonal 2

Antibacterial comes with types bacterial - sucdesptile host, presence, pathogen and more Also Inflammation Sudden short duration

• Histmaince releases

• Acute is slow Bleeding anging is

• And a series reaction is not

• gingivitis