What are chemical mediators of inflammation?
Chemical mediators of inflammation are molecules that are released by cells involved in the inflammatory response and act to regulate and amplify the inflammatory process. Here are some key chemical mediators of inflammation:
1. Histamine: Histamine is a major inflammatory mediator released by mast cells, basophils, and platelets. It causes vasodilation, increased vascular permeability, and smooth muscle contraction, leading to the characteristic symptoms of inflammation such as redness, swelling, and pain.
2. Prostaglandins: Prostaglandins are a group of lipid mediators derived from arachidonic acid metabolism by the action of the enzyme cyclooxygenase (COX). They have diverse effects, including vasodilation, increased vascular permeability, pain sensitization, and fever.
3. Leukotrienes: Leukotrienes are another group of lipid mediators derived from arachidonic acid metabolism through the 5-lipoxygenase pathway. They contribute to increased vascular permeability, bronchoconstriction, and chemotaxis of inflammatory cells.
4. Cytokines: Cytokines are small secreted proteins that play crucial roles in regulating the immune response and inflammation. Pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6), promote inflammation by stimulating the production of other inflammatory mediators and recruiting inflammatory cells to the site of injury or infection.
5. Chemokines: Chemokines are a family of small proteins that function as chemoattractants for various types of immune cells. They direct the migration of leukocytes, including neutrophils, monocytes, and lymphocytes, to the site of inflammation.
6. Nitric oxide (NO): NO is a gaseous molecule produced by inducible nitric oxide synthase (iNOS) in response to inflammatory stimuli. It has vasodilatory effects, can inhibit platelet aggregation, and plays a role in the defense against pathogens.
7. Reactive oxygen species (ROS): ROS are generated by various cells involved in inflammation, including neutrophils and macrophages. They participate in microbial killing, but excessive ROS production can also cause tissue damage and contribute to chronic inflammatory conditions.
8. Eicosanoids: Eicosanoids are signaling molecules produced from essential fatty acids such as arachidonic acid. They include prostaglandins, leukotrienes, and thromboxanes, and participate in various aspects of inflammation such as vasodilation, pain, and fever.
These are just a few examples of the many chemical mediators involved in inflammation. Their coordinated release and interaction contribute to the complex and multifaceted nature of the inflammatory response.