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Monocyte‐derived fibrocytes induce an inflammatory phenotype in airway smooth muscle cells
Author(s) -
Lin T.Y.,
Venkatesan N.,
Nishioka M.,
Kyoh S.,
AlAlwan L.,
Baglole C. J.,
Eidelman D. H.,
Ludwig M. S.,
Hamid Q.
Publication year - 2014
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1111/cea.12421
Subject(s) - fibrocyte , eotaxin , chemokine , myosin light chain kinase , chemistry , immunology , ovalbumin , monocyte , microbiology and biotechnology , inflammation , biology , myosin , medicine , pathology , immune system
Summary Background Infiltration of fibrocytes (FC) in the airway smooth muscle is a feature of asthma, but the pathological significance is unknown. Objective We sought to explore whether FC modulate the phenotype of airway smooth muscle cells (ASMC) in asthmatic vs. control subjects. Methods Fibrocytes were isolated from CD14+ monocytes from asthmatic and normal subjects. Proliferation of ASMC of asthmatic or normal subjects was analysed by 3 H‐thymidine incorporation, cell number counting and Ki‐67 expression after treatment of ASMC with FC‐conditioned medium (FCCM) or co‐culture with FC. ASMC‐associated cytokines/chemokines implicated in asthma (TGF‐β1, eotaxin, IL‐6 and IL‐8) were measured in co‐culture or transwell culture of ASMC + FC by ELISA. Immunofluorescence staining was performed to localize these cytokines in ASMC. Cytokine secretion was measured in the transwell culture of ASMC + FC, where NF‐κB‐p65 or ERK1/2 in ASMC was silenced by siRNA. Contractile phenotype of ASMC in transwell culture was assessed by immunoblotting of α‐smooth muscle actin (α‐SMA) and myosin light chain kinase (MLCK). Results Fibrocytes did not affect ASMC proliferation and expression of TGF‐β1, eotaxin, α‐SMA and MLCK; however, ASMC production of IL‐8 and IL‐6 was increased in the co‐culture and transwell culture by FC. ASMC treated with FCCM were immunopositive for IL‐8/IL‐6 and produced more IL‐8/IL‐6. Furthermore, siRNA silencing of NF‐κB‐p65 or ERK1/2 in transwell cultures of asthmatic ASMC with normal subject FC decreased IL‐8 and IL‐6 production. Conclusions and Clinical Relevance Fibrocytes promoted IL‐8 and IL‐6 production by ASMC, demonstrating a proinflammatory role for FC and a possible mechanism of the inflammatory phenotype in asthma.