Role of free Radicals

Inflammatory Diseases

Inflammation is characterized by a respiratory burst of activated neutrophils and macrophages, leading to the destruction of invading micro-organisms. This mechanism is a useful function protecting against attack, however the inflammatory response can also be detrimental as it is non-specific and may lead to the development of inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease, psoriasis, etc,. Reactive oxygen species (ROS) and free radicals are thought to act indirectly as cellular messengers and elicit an inflammatory response. Over production of these species may cause oxidative modification of biological molecules e.g. trypsin, collagen, LDL, DNA and lipids. ROS and free radicals also activate a series of enzyme systems, including protein kinases, protein phosphatases, transcription factors and heat shock proteins. ROS are also critical for gene expression which encode inflammatory proteins e.g. proteinases involved in tissue destruction such as collagenases and gelatinases. Nuclear factor-kß (NF-kß) has been implicated in AIDS, as HIV is NF-kß dependent. In the case of rheumatoid arthritis, rheumatoid factor binds IgG when it is exposed to free radicals. This binding stimulates the production of more free radicals, which then attack the cartilage matrix.

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