Ccl24

Chemokines, a subgroup of cytokines, are small (size between 8 and 10 kDa), chemotactically active proteins (signal proteins). They are common in all vertebrates, in some virus species and bacteria. In humans, about 50 chemokines are currently known. A highly conserved structural feature of all chemokines is a fixed group of cysteine residues stabilized by 1 or 2 disulfide bridges. This key structural position in the molecule is responsible for their fixed 3-dimensional structure.

In CC chemokines, the cysteines follow each other directly, inCXC chemokinesthey are separated (CC = acronym for cysteine-cysteine) by 1, in CXXXC chemokines by 3 other amino acids. Chemokines are produced and secreted by a variety of immune cells, but also by parenchymal cells (e.g. hepatocytes, myocytes). They mediate their signals by binding to chemokine receptors via G-proteins (see below Chemokine receptors). Some chemokines have a proinflammatory effect, others have a regulatory effect on the formation and homeostasis of tissues.

CCL24 (CC-chemokine ligand 24) is a small cytokine of the CC-chemokine family. In humans, CCL24 is encoded by the CCL24 gene, which is located on chromosome 7. The chemokine is mainly involved in inflammatory (allergic) processes, but also in the pathogenesis of tumors. CCL24 (like CCL26) is a ligand for the CCR3 receptor.

The chemokine acts as an attractor for eosinophilic and (to a lesser extent) neutrophilic granulocytes as well as for resting T cells.

Sharifabadi AR et al (2014) were able to demonstrate in patients with pulmonary tuberculosis that the serum levels (produced by Th2 cells) of the chemokines CCL11, CCL24 and CCL26 are elevated compared to control persons.

CCL11, CCL24, and CCL26 are chemokines (family of eotaxins) that act as attractors of eosinophilic granulocytes mainly via the CCR3 receptor.

In patients with allergic bronchial asthma, CCL26 has the strongest chemotactic effect. Blocking the CCR3 receptor with the antibody (CCR3 mAb) leads to a CCL24-induced migration inhibition of eosinophilic granulocytes.

CCL24 is also involved in the pathogenesis of acetylsalicylic acid-induced bronchial asthma.

In lesional skin of patients with (extrinsically safe) atopic dermatitis an increased gene expression for the eotaxins CCL11, CCL24, CCL26 can be detected compared to healthy persons. Apparently the pathogenetic significance of CCL26 is higher in comparison to CCL24.

Also in patients with allergic keratoconjunctivitis, the cytokines CCL17, CCL24 and IL-16 measured in the tear fluid are evaluated as biomarkers.

In various tumors (such as colorectal carcinoma - C19), the serum levels of the chemokines CCL11 and CCL24 have a diagnostic and prognostic value as tumor markers. It could be shown that the expression of CCL11 and CCL24 in glandular cells decreased with tumor progression (in parallel the number of eosinophilic cells in the tissue decreased).

1. Cho H et al (2016) Eosinophils in Colorectal Neoplasms Associated with Expression of CCL11 and CCL24.J Pathol Transl Med 50:45-51.
2. Owczarek W et al (2010) Analysis of eotaxin 1/CCL11, eotaxin 2/CCL24 and eotaxin 3/CCL26 expression in lesional and non-lesional skin of patients with atopic dermatitis. Cytokines 50:181-185.
3. Provost V et al (2013) CCL26/eotaxin-3 is more effective to induce the migration of eosinophils of asthmatics than CCL11/eotaxin-1 and CCL24/eotaxin-2. J Leukoc Biol 94:213-222.
4. Sharifabadi AR et al,(2014) All eotaxins CCL11, CCL24 and CCL26 are increased but to various extents in pulmonary tuberculosis patients. Clin Lab 60:93-97.
5. Shoji J et al.(2016) Clinical Usefulness of Simultaneous Measurement of the Tear Levels of CCL17, CCL24, and IL-16 for the Biomarkers of Allergic Conjunctival Disorders. Curr Eye Res 29:1-8.