Chemical Mediators of Inflammation Quiz

Chemical Mediators & Regulators of Inflammation

Inflammation is a complex physiological response of the body to injury or infection. It involves the release of various chemical mediators and regulators that help control the immune response and promote tissue repair. This article will discuss some key players in the inflammatory process: vasoactive amines, cytokines, arachidonic acid metabolites, reactive oxygen species (ROS), and nitric oxide.

Vasoactive Amines

Vasoactive amines, including histamine, serotonin, dopamine, and noradrenaline, play crucial roles in inflammation. They mediate vascular permeability, smooth muscle contraction, and blood flow changes. For example, histamine increases vascular permeability, allowing immune cells to enter damaged tissues. Dopamine, noradrenaline, and serotonin typically cause vasoconstriction, which reduces blood flow, lowers edema formation, and thus mitigate inflammation.

Cytokines

Cytokines are signaling proteins involved in cell signaling, particularly those responsible for the inflammatory response. They are produced by various immune cells and act as messengers, coordinating communication among different parts of the immune system. Examples include interleukins (IL-1 through IL-10), tumor necrosis factor-alpha (TNF-α), and interferons (IFNs). Some cytokines induce fever, while others regulate immune cell proliferation and activate other components of the immune system.

Arachidonic Acid Metabolites

Arachidonic acid (AA) is a long-chain polyunsaturated omega-6 fatty acid that serves as a precursor for prostaglandins, thromboxanes, prostacyclin, and leukotrienes. These compounds modulate various aspects of inflammation, like pain, fluid leakage, and blood vessel dilation. Mediated by cyclooxygenase (COX) and lipoxygenase (LOX) enzymes, AA metabolites contribute to the protective effect during an inflammatory episode.

Reactive Oxygen Species (ROS)

Reactive oxygen species (ROS) are unstable molecular compounds containing oxygen-derived free radicals or non-radical derivatives. ROS can be generated by phagocytes (white blood cells) during the respiratory burst, a rapid acceleration in oxygen consumption catalyzed by NADPH oxidase, upon encountering certain bacteria or microorganisms. ROS are also produced by endothelial cells exposed to leukotriene B4. Their purpose includes contributing to host defense and wound healing.

Nitric Oxide

Nitric oxide (NO) is a reactive gas that acts as both a neurotransmitter and a potent vasodilator. Produced from L-arginine by nitric oxide synthases (NOS), it helps lower blood pressure, inhibit platelet aggregation, and reduce inflammation. NO has significant implications in atherogenesis, angiogenesis, and myocardial infarction.

The balance of these various chemical mediators and regulators is crucial to ensure proper inflammatory responses without causing excessive damage. Enhanced understanding of these interactions may inform the design of targeted therapies aimed at resolving inflammation effectively, minimizing side effects, and ensuring better outcomes for patients.