1. Academic Validation
  2. What does elevated TARC/CCL17 expression tell us about eosinophilic disorders?

What does elevated TARC/CCL17 expression tell us about eosinophilic disorders?

  • Semin Immunopathol. 2021 Jun;43(3):439-458. doi: 10.1007/s00281-021-00857-w.
Julien Catherine 1 2 Florence Roufosse 3 4
Affiliations

Affiliations

  • 1 Department of Internal Medicine, Hôpital Erasme, 808 Route de Lennik, 1070, Brussels, Belgium. [email protected].
  • 2 Institute for Medical Immunology, Université Libre de Bruxelles, 6041 Gosselies, Brussels, Belgium. [email protected].
  • 3 Department of Internal Medicine, Hôpital Erasme, 808 Route de Lennik, 1070, Brussels, Belgium.
  • 4 Institute for Medical Immunology, Université Libre de Bruxelles, 6041 Gosselies, Brussels, Belgium.
Abstract

Eosinophilic disorders encompass a large spectrum of heterogeneous diseases sharing the presence of elevated numbers of eosinophils in blood and/or tissues. Among these disorders, the role of eosinophils can vary widely, ranging from a modest participation in the disease process to the predominant perpetrator of tissue damage. In many cases, eosinophilic expansion is polyclonal, driven by enhanced production of interleukin-5, mainly by type 2 helper cells (Th2 cells) with a possible contribution of type 2 innate lymphoid cells (ILC2s). Among the key steps implicated in the establishment of type 2 immune responses, leukocyte recruitment toward inflamed tissues is particularly relevant. Herein, the contribution of the chemo-attractant molecule thymus and activation-regulated chemokine (TARC/CCL17) to type 2 immunity will be reviewed. The clinical relevance of this chemokine and its target, C-C Chemokine Receptor 4 (CCR4), will be illustrated in the setting of various eosinophilic disorders. Special emphasis will be put on the potential diagnostic, prognostic, and therapeutic implications related to activation of the TARC/CCL17-CCR4 axis.

Keywords

C-C chemokine receptor 4 (CCR4); CCL17; Eosinophilic disorders; Eosinophils; Hypereosinophilic syndromes; Thymus and activation-regulated chemokine (TARC).

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