IL1Rs

IL1Rs refers to the receptors for Interleukin-1 (IL-1). Interleukin-1 is a key cytokine involved in the immune response, inflammation, and cell proliferation. There are two main types of IL-1 receptors: IL-1R1 and IL-1R2.

IL-1R1 is the primary signaling receptor for IL-1. Upon binding of IL-1 cytokines (specifically IL-1 alpha and IL-1 beta) to IL-1R1, a cascade of intracellular events is triggered, leading to the activation of signaling pathways such as NF-κB and MAPK. This activation results in the production of pro-inflammatory mediators and other cellular responses. IL-1R1 is expressed on a wide variety of cell types, including immune cells, endothelial cells, and fibroblasts.

IL-1R2, also known as the decoy receptor, binds IL-1 but does not typically initiate downstream signaling. Instead, it is thought to act as a negative regulator of IL-1 signaling by competing with IL-1R1 for IL-1 binding. This can help to dampen excessive inflammatory responses. IL-1R2 is found on certain immune cells, such as B cells and macrophages, as well as on some non-immune cells.

A third receptor, IL-1RAP (IL-1 Receptor Accessory Protein), is a co-receptor that forms a complex with IL-1R1. This complex is essential for efficient IL-1 signaling through IL-1R1. IL-1RAP enhances the binding affinity of IL-1 to IL-1R1 and is crucial for the proper transmission of the IL-1 signal. The IL-1 receptor system plays a vital role in host defense against infection and in various inflammatory and autoimmune diseases.