Inflammatory Mediators Overview
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Questions and Answers

What is the role of phospholipase A2 in the synthesis of eicosanoids?

Phospholipase A2 catalyzes the release of arachidonic acid from membrane phospholipids, initiating the synthesis of eicosanoids.

Name two types of eicosanoids derived from arachidonic acid.

Prostaglandins and leukotrienes are two types of eicosanoids derived from arachidonic acid.

How do NSAIDs work in relation to the cyclooxygenase pathway?

NSAIDs inhibit the cyclooxygenase (COX) enzymes, specifically blocking the formation of prostaglandins and thromboxane.

What critical role do eicosanoids play during inflammation?

<p>Eicosanoids regulate various aspects of inflammation, including vascular and bronchial tone.</p> Signup and view all the answers

What distinguishes COX-1 from COX-2 in the context of inflammation?

<p>COX-1 is involved in the production of protective prostaglandins, while COX-2 is induced during inflammation to produce pro-inflammatory prostaglandins.</p> Signup and view all the answers

What are lipoxins and their significance in inflammation?

<p>Lipoxins are a type of eicosanoid that help to resolve inflammation by promoting the clearance of inflammatory cells.</p> Signup and view all the answers

Describe the significance of the metabolism of arachidonic acid.

<p>The metabolism of arachidonic acid is vital for producing bioactive lipid mediators like eicosanoids, which regulate inflammatory responses.</p> Signup and view all the answers

What is the function of prostacyclins in the body?

<p>Prostacyclins act as vasodilators and promote the release of cytokines, thereby playing a role in the regulation of blood flow and inflammation.</p> Signup and view all the answers

What is the role of 5-LOX in the synthesis of inflammatory mediators?

<p>5-LOX is crucial for converting arachidonic acid into leukotrienes, such as LTB4 and LTC4, which are significant inflammatory mediators.</p> Signup and view all the answers

How do NSAIDs affect the synthesis of inflammatory mediators?

<p>NSAIDs inhibit the cyclooxygenase (COX) enzymes, preventing the conversion of arachidonic acid into prostaglandins and thromboxane.</p> Signup and view all the answers

What inflammatory mediators are derived from arachidonic acid through the LOX pathway?

<p>The LOX pathway produces leukotrienes, including LTB4 and cysteinyl leukotrienes, as well as lipoxins.</p> Signup and view all the answers

In what way do prostaglandins contribute to the inflammatory response?

<p>Prostaglandins mediate processes such as vasodilation, increased vascular permeability, and pain during inflammation.</p> Signup and view all the answers

What impact does blocking arachidonic acid pathways have on inflammation?

<p>Blocking these pathways decreases the production of inflammatory mediators, resulting in reduced swelling, pain, and fever.</p> Signup and view all the answers

What is the difference between COX-1 and COX-2 in terms of their role in inflammation?

<p>COX-1 is involved in maintaining normal physiological functions, while COX-2 is primarily induced during inflammation.</p> Signup and view all the answers

Describe the synthesis and role of lipoxins in inflammation.

<p>Lipoxins are synthesized through the action of 15-LOX on arachidonic acid and act as anti-inflammatory mediators.</p> Signup and view all the answers

What is the significance of the irreversible action of aspirin compared to other NSAIDs?

<p>Aspirin irreversibly inhibits COX enzymes, providing prolonged anti-inflammatory effects compared to reversible inhibitors.</p> Signup and view all the answers

What are the primary differences between COX-1 and COX-2 in terms of expression and tissue location?

<p>COX-1 is constitutively expressed and found in ubiquitous tissues, while COX-2 is inducible and primarily located in inflamed tissues.</p> Signup and view all the answers

How do COX-1 and COX-2 differ in terms of their roles in inflammatory processes?

<p>COX-1 is involved in protection and maintenance functions, while COX-2 plays a role in pro-inflammatory activities.</p> Signup and view all the answers

What types of mediators are produced as a result of COX enzymatic activity on arachidonic acid?

<p>COX activity on arachidonic acid produces prostaglandins and thromboxane.</p> Signup and view all the answers

Describe the substrate that COX enzymes act upon and name one specific outcome of this enzymatic action.

<p>COX enzymes act on arachidonic acid, leading to the production of PGG2 as an intermediate.</p> Signup and view all the answers

What is the role of PGE2 in the inflammatory response?

<p>PGE2 is involved in vasodilation, hyperalgesia, fever, and immunomodulation.</p> Signup and view all the answers

What pathway is involved in the synthesis of leukotrienes and lipoxins, and how does it relate to COX activity?

<p>The lipoxygenase (LOX) pathway synthesizes leukotrienes and lipoxins, which are alternatives to the COX pathway for processing arachidonic acid.</p> Signup and view all the answers

Identify and explain the function of one inflammatory mediator produced by the COX pathways.

<p>Thromboxane promotes platelet aggregation, contributing to hemostasis.</p> Signup and view all the answers

How does the location of COX-2's expression impact its function during inflammation?

<p>COX-2's expression in inflamed tissue allows it to respond to inflammatory stimuli and enhance the inflammatory response.</p> Signup and view all the answers

Study Notes

Inflammatory Mediators

  • Inflammation is the body's immune system response to stimuli, crucial for fighting harmful substances like pathogens, but uncontrolled inflammation can cause chronic disease.
  • Inflammation is characterized by redness, swelling, warmth, and sometimes pain and immobility.
  • Inflammation can be acute (temporary) or chronic (persistent). Acute inflammation often results from injuries, infections, or toxins, while chronic inflammation can lead to conditions like asthma and rheumatoid arthritis.
  • The inflammatory process involves communication between injured tissue and the immune system, and a coordinated response that includes recruitment of immune cells to the site of damage, to help remove harmful stimuli and promote repair.

Types of Inflammatory Mediators

  • Eicosanoids: Synthesized rapidly in response to stimuli, acting locally (e.g., prostaglandins and leukotrienes). A major target for pharmacological intervention.
  • Complement (e.g., C3/C5): Essential early response to injury. Recognises pathogens, recruits phagocytes (cells that engulf and destroy pathogens).
  • Histamine: Released by mast cells, primary mediator in allergic reactions; effects mainly occur in the blood vessels.
  • Cytokines (e.g., interleukins, TNFα, TGFβ) and chemokines: Essential for the orchestration of the immune and inflammatory responses, playing a critical role in the acute inflammatory response and chronic inflammatory diseases. Secreted by various cell types like epithelial cells and immune cells.
  • Other Agents: Include nitric oxide (NO) and bacterial products (e.g., LPS).

Causes of Acute Inflammation

  • Injury: Physical injuries like cuts, trauma, surgical procedures, and hypoxia (lack of oxygen).
  • Pathogenic: Microbial infections and parasites.
  • Toxins: Toxins released by bacteria, plants, etc.
  • All the above trigger an acute inflammatory response.

Acute Inflammation Process

  • Dilation of blood vessels: Vasculature around injury site reacts to recruit immune cells.
  • Recruitment of immune cells: Circulating immune cells migrate from vessels to the injured tissue.
  • Chemotaxis: Immune cells move towards the location of the inflammation.
  • Phagocytosis: Immune cells engulf and destroy harmful substances/ pathogens.
  • Resolution: The inflammatory response ends, the damaged tissue heals.

Pharmacological Targets and Therapies

  • Pharmacological targets in inflammation can differ based on the acute or chronic nature of the condition. Strategies focus on modulation of eicosanoids and histamine signaling.
  • COX-1 and COX-2 inhibitors (NSAIDs) are commonly used. They inhibit prostaglandin synthesis.
  • Leukotriene inhibitors target leukotrienes, important for inflammation and allergic responses.
  • Antihistamines block histamine receptors, to help manage allergic reactions.
  • Steroid-based anti-inflammatories (e.g., corticosteroids) regulate gene expression and suppress inflammation by acting on cytokines. They are commonly used.

Innate Immunity Cell Types and Their Function

  • Macrophages: Phagocytose cellular and foreign debris and present antigens; link to the acquired immune response.
  • Neutrophils: Phagocytose bacteria.
  • Eosinophils: Defend against parasites.
  • Basophils/Mast cells: Release histamine, leukotrienes, and other mediators after antigen exposure to activate an allergic response.

Summary

  • Inflammation is an essential defense mechanism but can lead to chronic disease if not resolved properly.
  • Acute inflammation has four key steps (dilation of vessels, recruitment, chemotaxis, phagocytosis- resolution). Inhibiting the arachidonic acid pathways can help manage the inflammation process.
  • Various drugs target specific inflammatory mediators, such as cytokines, eicosanoids, and histamine, to control the inflammatory process.

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Inflammatory Mediators PDF

Description

This quiz delves into the role and types of inflammatory mediators in the body's immune response. Learn about the characteristics of inflammation, its acute and chronic forms, and the key mediators involved such as eicosanoids and complement proteins. Understand how these factors contribute to both healing and chronic diseases.

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