Inflammation
The body's protective response to injury, infection, or irritation, characterised by redness, swelling, heat, pain, and loss of function. Acute inflammation is beneficial for healing, but chronic inflammation contributes to many diseases. Multiple peptide drugs have anti-inflammatory properties.
Technical Context
Cardinal signs (Celsius/Virchow): rubor (redness — vasodilation), calor (heat — increased blood flow), tumor (swelling — plasma exudation from increased vascular permeability), dolor (pain — nociceptor sensitisation by bradykinin, prostaglandins, cytokines), and functio laesa (loss of function). Molecular mediators: histamine and serotonin (vasoactive amines from mast cells — immediate), prostaglandins and leukotrienes (lipid mediators from arachidonic acid — sustained), cytokines (TNF-α, IL-1β, IL-6 — amplifying and perpetuating), chemokines (directing cell recruitment), complement fragments (C3a, C5a — promoting inflammation), and bradykinin (vasodilation, pain). The resolution of inflammation is an active, programmed process involving: lipid mediator class switching (pro-inflammatory prostaglandins → pro-resolving lipoxins, resolvins, protectins), efferocytosis (macrophages clearing apoptotic neutrophils → triggering anti-inflammatory reprogramming), and Treg cell activation. Failed resolution → chronic inflammation.