Author: Prof. Dr. med. Peter Altmeyer

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Last updated on: 29.10.2020

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A-152E5.3; ABCD-2; C-C motif chemokine ligand 17; SCYA17; TARC

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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. Here we show that CCL15 are processed in human synovial fluid by matrix metalloproteinases (MMPs) and serine proteases, produced and secreted by a variety of immune cells. They mediate 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.

CCL17, also known as C-C motif chemokine ligand 17 or TARC (thymus activity regulated chemokine) is a small, human cytokine belonging to the CC chemokine family. The coding CCL17 gene is located on chromosome 16 in humans together with the genes for the chemokines CCL22 and CX3CL1. Like CCL22, CCL17 binds to the chemokine receptor CCR4.

General information
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Diseases associated with increased expression of CCL17 are atopic diseases such as atopic dermatitis or type I-associated food allergies; furthermore, elevated levels of eosinophilic pneumonia and idiopathic pulmonary fibrosis have been detected. In children with atopic diseases (inhaled or nutritive type I allergies) a clear correlation between serum levels of CCL17 and the extent and intensity of allergic symptoms(SCORAD) has been demonstrated.

Apparently, CCL17 is also expressed non-specifically (by alveolar macrophages); this suggests elevated CCL17 levels in chronic smokers.

In chronic discoid lupus erythematosus CCR4+ cytotoxic T cells were markedly overexpressed in lesional skin. CCL4 was elevated in lesional skin and serum (?).

CCL17 could be detected in high concentrations in damaged tissue in arteriosclerosis.

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  1. Ahrens B et al (2015) Chemokine levels in serum of children with atopic dermatitis with regard to severity and sensitization status. Pediatric Allergy Immunol 26:634-640.
  2. Fujisawa T et al (2009) Serum measurement of thymus and activation-regulated chemokine/CCL17 in children with atopic dermatitis: elevated normal levels in infancy and age-specific analysis in atopic dermatitis. Pediatric Allergy Immunol 20:633-641.
  3. Imai T et al (1997) The T cell-directed CC chemokine TARC is a highly specific biological ligand for CC chemokine receptor 4 J Biol Chem 272:15036-15042.
  4. Kapitány A et al (2017) CD1c+ Blood Dendritic Cells in Atopic Dermatitis are Premature and Can Produce Disease-specific Chemokines. Acta Derm Venereol 97:325-331.
  5. Takeuchi S et al (2015) Incidence, serum IgE and TARC/CCL17 levels in atopic dermatitis associated with other allergic diseases: an update from the Ishigaki cohort. Acta Derm Venereol 95:480-484.
  6. Ritter M et al (2005) Elevated expression of TARC (CCL17) and MDC (CCL22) in models of cigarette smoke-induced pulmonary inflammation. Biochem Biophys Res Commun 334:254-262.
  7. Wenzel J et al (2005) Role of the chemokine receptor CCR4 and its ligand thymus- and activation-regulated chemokine/CCL17 for lymphocyte recruitment in cutaneous lupus erythematosus. J Invest Dermatol 124:1241-1248.
  8. Yogo Y et al (2009) Macrophage derived chemokine (CCL22), thymus and activation-regulated chemokine(CCL17), and CCR4 in idiopathic pulmonary fibrosis. Respir Res 10:80.

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Chemokines; Tarc;


Last updated on: 29.10.2020