inflammation

Inflammation is a protective response of the body's immune system to tissue injury or infection, aimed at eliminating the cause of damage, removing dead cells, and initiating healing. It involves vascular changes, activation of leukocytes, and the release of chemical mediators that coordinate the response.

The classical signs of inflammation—redness, heat, swelling, pain, and sometimes loss of function—result from vasodilation, increased vascular permeability, and the accumulation of fluid and immune cells at the affected site. Triggers include microbial infection, physical injury, chemical irritants, and autoimmune processes.

In acute inflammation, neutrophils are among the first responders. Endothelial cells lining blood vessels become permeable, allowing proteins and leukocytes to migrate into tissue. Mediators such as histamine, prostaglandins, leukotrienes, cytokines (e.g., TNF, IL-1), and the complement system orchestrate these events and help destroy invading agents and begin repair.

If the inciting stimulus is removed, inflammation can resolve with clearance of debris and restoration of tissue architecture. When the stimulus persists, inflammation may become chronic, with macrophages and lymphocytes driving ongoing tissue damage and attempts at repair, which can lead to fibrosis or granuloma formation.

Clinical relevance includes signs and symptoms, laboratory markers (such as elevated C-reactive protein or erythrocyte sedimentation rate), and imaging findings. Management focuses on treating the underlying cause and may involve anti-inflammatory medications, analgesia, antibiotics for infection, or immunomodulatory therapies in autoimmune conditions.