Inflammatory mediators are bioactive substances released by immune cells and damaged tissues during an inflammatory response, including cytokines, chemokines, and prostaglandins. They play a crucial role in regulating inflammation, modulating immune responses, and facilitating tissue repair, making them significant in understanding various diseases, including autoimmune disorders and infections. An example of a key inflammatory mediator is tumour necrosis factor-alpha (TNF-α), which is implicated in rheumatoid arthritis.