Inflammation: An Overview

Definition

• Local immune response to tissue injury or infection.
• Symptoms: heat, redness, edema, pain, and loss of function.

Initial Response to Injury

1. Vasoconstriction:

   • Brief constriction of local blood vessels to reduce blood loss.
   • Formation of a clot to stop bleeding.

2. Vasodilation:

   • Triggered by cell injury and death.
   • Local cells release vasoactive chemicals (e.g., prostaglandins, histamine).
   • Leads to increased blood flow to the area.
   • Endothelial cells contract, increasing capillary permeability.
   • Fluids and proteins pass from blood to tissue.

Chemotaxis Process

• Definition: Multi-stage process guiding immune cells to the injury site.
• Neutrophils: Circulating immune cells that move out of blood vessels to destroy pathogens and damaged cells.

Stages of Chemotaxis

1. Release of Chemoattractants:

   • Cells at the injury site release messenger molecules.
   • Causes local endothelial cells and circulating neutrophils to adhere.

2. Diapedesis:

   • Neutrophils squeeze through gaps in the endothelium.
   • Migrate to the injury site following a chemotactic gradient.

3. Phagocytosis:

   • Neutrophils encounter, engulf, and digest bacteria.

Tissue Repair

• Following the destruction of pathogens and waste removal,
• Growth Factors: Locally produced growth factors stimulate fibroblast division and collagen secretion to reinforce the wound.

Anti-Inflammatory Drugs

• Function: Inhibit inflammation by blocking the production of inflammatory chemicals.
• Common Drugs: Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen.
• Mechanism: Contain cyclooxygenase (Cox) enzyme, inhibiting production of prostaglandins and other inflammatory chemicals, thus reducing vasodilation, edema, and pain.