Functional expression of IgG-Fc receptors in human airway smooth muscle cells

Yuxiu C. Xia, Michael Schuliga, Malcolm Shepherd, Maree Powell, Trudi Harris, Shenna Y. Langenbach, Peck Szee Tan, William T Gerthoffer, P. Mark Hogarth, Alastair G. Stewart, Graham A. Mackay

Research output: Contribution to journalArticleResearchpeer-review

16 Citations (Scopus)

Abstract

IgE-Fc receptors and IgG-Fc receptors are expressed on hematopoietic cells, but some evidence suggests that these receptors are also found on nonhematopoietic cells, including human airway smooth muscle(hASM)cells.Ourstudy characterizes the expression of IgE-Fc receptors (FcεRI/CD23) and IgG-Fc receptors (FcγRs-I, -II, and -III) in cultured hASM cells by flow cytometry and Western blotting, and the functional activity of receptors was determined through quantification of cell proliferation and released cytokines. Expression of Fc receptor-linked intracellular signaling proteins and phosphorylation of the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase 1/2 and p38 MAPK in hASM cells was examined by Western blotting. Expression of FcεRI and CD23 was not detectable in hASM cells. However, FcγRI and FcγRII were shown to be expressed on these cells. Specific antibodies, validated using transfected cell lines, revealed that the inhibitory IgG receptor, FcγRIIb, was the most abundant Fc receptor subtype expressed. Althoughcross-linking FcγR with heat-aggregated γ globulin(HAGG) did not induce detectable cell stimulation, pretreating hASM cells with HAGG significantly inhibited IL-1α-induced increases incytokine levels and basic fibroblast growth factor-induced cell proliferation. This inhibitory effect of HAGG was abrogated by preincubation of cells with an anti-FcγRIIb antigen-binding fragment (Fab). Expression of proteins involved in the canonical FcγRIIb inhibitory signaling pathway was established in hASM cells. Pretreatment of hASM cells with HAGG significantly inhibited IL-1α- and basic fibroblast growth factor-induced extracellular signal-regulated kinase 1/2 and p38 MAPK phosphorylation. This study identifies functional expression of FcγRIIb in hASM cells, with the potential to suppress their remodeling and immunomodulatory roles.

Original languageEnglish
Pages (from-to)665-672
Number of pages8
JournalAmerican Journal of Respiratory Cell and Molecular Biology
Volume44
Issue number5
DOIs
Publication statusPublished - 1 May 2011
Externally publishedYes

Keywords

  • Airway remodeling
  • Airway smooth muscle
  • Asthma
  • Ig receptors
  • Mitogenactivated protein kinases

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