Interleukin-27

Interleukins (from Latin/Greek inter = between; leukos = white; kinein = to move) are a group of endogenous, short-chain regulatory proteins (cytokines) of the immune system (IL1-IL38). Interleukins are mediators for induction, course and control of T-cell-mediated cytotoxic immune reactions as well as B-cell activation (antibody production). They are mainly formed and secreted by stimulated leukocytes, monocytes and macrophages. So far, about 38 different interleukins have been clearly identified. Each cytokine of the interleukin group is nomenclatically assigned a number for its classification (IL-1 to IL-38).

Some structurally related substances have been grouped into families. Their members often have a similar function or participate in the fine regulation of immune reactions, for example by regulating the synthesis of related interleukins.

Interleukin-27 is a heterodimeric, regulatory cytokine that belongs to the Interleukin-12/Interleukin-23 family. The cytokine was discovered in 2002.

There is a closer molecular relationship between interleukin-27 and interleukin-30. interleukin-30 is the alpha subunit of IL-27 (IL-27p28) encoded by the Epstein-Barr virus-induced gene 3, also known as EBI3. IL-30, despite its identity with the alpha subunit, can be produced and secreted independently from IL-27.

It is involved in the pathogenesis of numerous inflammatory (also autoimmunological) diseases. These include rheumatoid arthritis, psoriasis, multiple sclerosis, Crohn's disease, ulcerative colitis and infectious diseases.

IL-27 is expressed by activated macrophages, dendritic cells, CD4+ T-cells (proven in malaria infection) and B cells. The cytokine interacts with its specific surface receptor complex, the IL-27 receptor IL-27R. This receptor complex consists of 2 proteins, IL-27alpha and gp130. After binding to its receptor, the complex activates the JAK/STAT and the p38 MAPK signalling pathway. The immunological effect can be described as dual, since both pro-inflammatory and anti-inflammatory processes are activated. Different cell types such as macrophages, dendritic cells, T and B cells are activated. The development of Th-17 cells is inhibited.

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