What is Inflammation?
Inflammation is the body's complex biological response to harmful stimuli, such as pathogens, damaged cells, or irritants. It is a defensive mechanism aimed at eliminating the initial cause of cell injury, clearing out necrotic cells and tissues, and establishing an environment conducive to tissue repair.
What are the Main Types of Inflammation?
Inflammation can be broadly classified into two main types:
acute and
chronic. Acute inflammation is the initial, rapid response to an injury, usually lasting for a few hours to a few days. Chronic inflammation is a prolonged response that occurs when the initial acute inflammatory response is insufficient to eliminate the harmful stimuli.
Vascular changes: Increased blood flow and permeability of blood vessels, leading to tissue edema.
Cellular infiltration: Migration of immune cells like neutrophils, macrophages, and lymphocytes to the site of inflammation.
Tissue damage: Resulting from the release of enzymes and reactive oxygen species by inflammatory cells.
Repair: Proliferation of fibroblasts and deposition of extracellular matrix, leading to scar formation.
Neutrophils: The first responders that phagocytose pathogens and release enzymes.
Macrophages: Engulf and digest cellular debris and microbes, and secrete cytokines to modulate the inflammatory response.
Lymphocytes: Include T-cells and B-cells, which are crucial for adaptive immunity.
Mast cells: Release histamine and other mediators that enhance vascular permeability.
Mononuclear cell infiltration: Presence of macrophages, lymphocytes, and plasma cells.
Tissue destruction: Caused by the persistent presence of the inflammatory stimulus.
Fibrosis: Due to the proliferation of fibroblasts and excessive deposition of collagen.
Granuloma formation: Aggregates of macrophages, often surrounded by lymphocytes, seen in diseases like tuberculosis.
How is Inflammation Resolved?
Resolution of inflammation involves the clearance of inflammatory cells and mediators, followed by tissue repair. This process is mediated by anti-inflammatory cytokines like IL-10 and TGF-beta, and involves the apoptosis of neutrophils and the phagocytosis of apoptotic cells by macrophages.
