DefinitionThis section has been translated automatically.
Chemokines, a subgroup of cytokines, are small (size between 8 and 10 kDa), chemotactically active proteins (signal proteins). They are common in all vertebrates, some virus types and bacteria. In humans, about 50 chemokines are currently known. A strongly conserved structural feature of all chemokines is a fixed group of cysteine residues that is stabilized by 1 or 2 disulfide bridges. This key structural position in the molecule is responsible for its fixed 3-dimensional structure.
In the CC chemokines, the cysteines follow each other directly (see figure), in the CXC chemokines they are separated (CC = acronym for cysteine-cysteine) by 1, in the CXXXC chemokines by 3 other amino acids. We show that CCL15 is processed in human synovial fluid by matrix metalloproteinases (MMPs) and serine proteases. They transmit their signals by binding to chemokine receptors via G-proteins. Some chemokines have a pro-inflammatory effect, others have a regulatory effect on the formation, homeostasis and proliferation of tissues.
General informationThis section has been translated automatically.
CCL22, also known as C-C motif chemokine ligand 22, or Stimulated T-Cell Chemotactic Protein 1 or MDC, is a small human cytokine belonging to the CC chemokine family. The chemokine is derived from the CCL22 gene on chromosome 16, which is adjacent to other chemokine genes such as CX3CL1 and CCL17.
CCL22, like CCL17, binds to the chemokine receptor CCR4. CCR4 is mainly expressed by Th2 cells (these Th2 cells dampen the expansion of pro-inflammatory cells); further by cutaneous lymphocytes, antigen-positive "skin-homing" T cells and Treg cells. Clear CCR4 expression occurs on neoplastic T cells in systemic and cutaneous T cell lymphomas.
CCL22 is induced by the cytokines interleukin-4 and interleukin-5 and downregulated by interferon-gamma. CCL22 binds to dendritic cells and TH2 cells, but not to neutrophil and eosinophil granulocytes or to resting T-lymphocytes.
CCL22 is involved in TH2 hypersensitivity of the respiratory tract and atopic dermatitis, here correlated with increased IgE.
Furthermore, CCL22 is increasingly expressed in autoimmune hepatitis (K75.4), which may be associated with other autoimmune diseases such as autoimmune thyroiditis, rheumatoid arthritis, vitiligo or alopecia areata, among others.
In acute disseminated encephalomyelitis (ADEM) the chemokines CCL22, CXCL7, CCL1 and CCL17 were significantly elevated in the cerebrospinal fluid. In multiple sclerosis (MS), no changes in the CCL22 value were found in diseased men, although the CCL22 values were significantly lower in diseased women.
LiteratureThis section has been translated automatically.
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