title: Activation of eosinophils interacting with dermal fibroblasts by pruritogenic cytokine IL-31 and alarmin IL-33: implications in atopic dermatitis.
abstract: BACKGROUND
  IL-31 is a pruritogenic cytokine, and IL-33 is an alarmin for damaging inflammation. They together relate to the pathogenesis of atopic dermatitis (AD). Eosinophil infiltration into the inner dermal compartment is a predominant pathological feature of AD. We herein investigated the in vitro inflammatory effects of IL-31 and IL-33 on the activation of human eosinophils and dermal fibroblasts.
  
  
  RESULTS
  Receptors, adhesion molecules and signaling molecules were assessed by Western blot or flow cytometry. Chemokines and cytokine were quantitated by multiplex assay. Functional IL-31 receptor component IL-31RA, OSMR-β and IL-33 receptor component ST2 were constitutively expressed on the surface of eosinophils. Co-culture of eosinophils and fibroblasts significantly induced pro-inflammatory cytokine IL-6 and AD-related chemokines CXCL1, CXCL10, CCL2 and CCL5. Such inductions were further enhanced with IL-31 and IL-33 stimulation. IL-31 and IL-33 could significantly provoke the release of CXCL8 from eosinophils and fibroblasts, respectively, which was further enhanced upon co-culture. In co-culture, eosinophils and fibroblasts were the main source for the release of CCL5, and IL-6, CXCL1, CXCL8, CXCL10 and CCL2, respectively. Direct interaction between eosinophils and fibroblasts was required for CXCL1, CXCL10, CXCL8 and CCL5 release. Cell surface expression of intercellular adhesion molecule-1 on eosinophils and fibroblasts was up-regulated in co-culture upon IL-31 and IL-33 stimulation. The interaction between eosinophils and fibroblasts under IL-31 and IL-33 stimulation differentially activated extracellular signal-regulated kinase, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, nuclear factor-κB and phosphatidylinositol 3-kinase-Akt pathways. Using specific signaling molecule inhibitors, the differential induction of IL-31 and IL-33-mediated release of cytokines and chemokines such as IL-6 and CXCL8 from co-culture should be related to their distinct activation profile of intracellular signaling pathways.
  
  
  CONCLUSIONS
  The above findings suggest a crucial immunopathological role of IL-31 and IL-33 in AD through the activation of eosinophils-fibroblasts interaction via differential intracellular signaling mechanisms.
authors.affiliation: Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, Special Administrative Region, People's Republic of China. ck-wong@cuhk.edu.hk
authors.forename: Chun-Kwok
authors.initials: CK
authors.lastname: Wong
authors.forename: Karen Ming-Lam
authors.initials: KM
authors.lastname: Leung
authors.forename: Huai-Na
authors.initials: HN
authors.lastname: Qiu
authors.forename: Joyce Yin-Sau
authors.initials: JY
authors.lastname: Chow
authors.forename: Angela On Kei
authors.initials: AO
authors.lastname: Choi
authors.forename: Christopher Wai-Kei
authors.initials: CW
authors.lastname: Lam
mesh_terms: D015153:Blotting, Western; D002450:Cell Communication / Q000187:drug effects* / Q000276:immunology; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000276:immunology / Q000378:metabolism; D018946:Chemokine CCL5 / Q000276:immunology / Q000378:metabolism; D054360:Chemokine CXCL1 / Q000276:immunology / Q000378:metabolism; D054357:Chemokine CXCL10 / Q000276:immunology / Q000378:metabolism; D018920:Coculture Techniques; D003876:Dermatitis, Atopic / Q000276:immunology / Q000378:metabolism; D020405:Dermis / Q000166:cytology; D004804:Eosinophils / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D015850:Interleukin-6 / Q000276:immunology / Q000378:metabolism; D016209:Interleukin-8 / Q000276:immunology / Q000378:metabolism; D007378:Interleukins / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000276:immunology / Q000378:metabolism; D018123:Receptors, Interleukin / Q000276:immunology / Q000378:metabolism; D011994:Recombinant Proteins / Q000276:immunology / Q000494:pharmacology
chemical_list: C111835:CCL2 protein, human; C483024:CCL5 protein, human; C475829:CXCL1 protein, human; C114753:CXCL10 protein, human; C508606:CXCL8 protein, human; D018932:Chemokine CCL2; D018946:Chemokine CCL5; D054360:Chemokine CXCL1; D054357:Chemokine CXCL10; C079241:IL1RL1 protein, human; C502187:IL31 protein, human; C502188:IL31RA protein, human; C506536:IL33 protein, human; D000072179:Interleukin-1 Receptor-Like 1 Protein; D000067596:Interleukin-33; D015850:Interleukin-6; D016209:Interleukin-8; D007378:Interleukins; D011956:Receptors, Cell Surface; D018123:Receptors, Interleukin; D011994:Recombinant Proteins