Inflammation

Inflammation (from Latin: inflammatio) is part of the biological defence response of body tissues. Inflammatory immunovascular responses can be triggered by a broad range of stimuli, including physical trauma, "dead, damaged, malfunctioning or stressed tissues", pathogens, irritants, toxins, overuse, autoimmunity, allergens, and foreign bodies (e.g. silica and asbestos). The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin calor, dolor, rubor, tumor, and functio laesa). Inflammation is a generic response, and therefore is considered a mechanism of innate immunity, not adaptive immunity. It involves immune cells, blood vessels, and molecular mediators. The function of inflammation is to eliminate the initial cause of cell injury, clear out damaged cells and tissues, and initiate tissue repair. Too little inflammation can lead to progressive tissue destruction by the harmful stimulus (e.g. bacteria) and compromise the survival of the organism, but too much inflammation, in the form of chronic inflammation, is associated with various diseases, such as hay fever, periodontal disease, atherosclerosis, and osteoarthritis. Inflammation can be classified as acute or chronic. Acute inflammation is the initial response of the body to harmful stimuli, and is achieved by the increased movement of plasma and leukocytes (in particular granulocytes) from the blood into the injured tissues. A series of biochemical events propagates and matures the inflammatory response, involving the local vascular system, the immune system, and various cells in the injured tissue. Chronic inflammation is prolonged inflammation that leads to a progressive shift in the type of cells present at the site of inflammation, such as mononuclear cells, and involves simultaneous destruction and healing of the tissue. Inflammation has also been classified as Type 1 and Type 2 based on the type of cytokines and T helper cells (Th1 and Th2) involved.