Interleukin-10

Interleukins (from Latin/Greek inter = between; leukos = white; kinein = to move) is the name given to a group of endogenous, short-chain regulatory proteins (cytokines) of the immune system (interleukin-1 to interleukin-35). Interleukins are mediators for induction, progression, and control of T-cell-mediated cytotoxic immune responses as well as B-cell activation (antibody production).

The gene encoding interleukin-10, as for interleukins-19 and -20, is located on chromosome 1q31-32.

Little is known about interleukin-10 receptors and the mechanism of signal transduction. IL10 is the defining cytokine of the "interleukin-10 family" with the homologous interleukins interleukin-19, -20 and interleukins -22, -24, -26.

The immunomodulatory interleukin-10 is secreted mainly by regulatory T cells (Treg). Furthermore, activated monocytes and mast cells secrete this cytokine.

Interleukin-10 inhibits the action of activated T cells and thus slows down the production of interferon-gamma. The cytokine acts (comparable to interleukins-4, -11 and TGF-beta) as a so-called anti-inflammatory cytokine by inhibiting macrophage function and thus preventing excessive inflammatory reactions (interleukin-10 apparently exerts a protective function in the formation of atherosclerotic plaques). In TH1 cells, but not in TH2 cells, it inhibits cytokine synthesis, e.g., of interferon gamma, interleukin-2, TNFbeta, and the chemokine CCL20.

Thus, interleukin-10 inhibits the formation of cytokines of the Th1 response. Moreover, interleukin-10, together with interleukin -2, interleukin-4 and interleukin -7, stimulates the growth of thymocytes and promotes the differentiation of cytotoxic T lymphocytes(CD8+T cells).

In addition, IL10 promotes the differentiation of B lymphocytes and induces the secretion of immunoglobulins (IgG, IgA and IgM) in activated cells.

In macrophages, interleukin-10 inhibits the synthesis of interleukin-1, interleukin-6, TNFalpha and inhibits antigen presentation. Effects In interaction with interleukin-3, interleukin-4 and peripheral lymphocytes, interleukin-10 stimulates mast cell proliferation. Several B-cell lymphomas also secrete interleukin-10.

There is ample evidence that IL-10 gene polymorphisms are associated with functional imbalances of the cytokine, with various diseases. These include:

• bronchial asthma
• SLE
• Pemphigus vulgaris
• Psoriasis
• Rheumatoid arthritis
• Arteriosclerosis
• and various neoplasias.

Interleukin-10 is particularly important for the immunology of the intestinal tract. Interleukin-10 deficiency is associated with a predisposition to chronic inflammatory bowel diseases such as Crohn's disease or ulcerative colitis.

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