Thy-1 attenuates TNF-alpha-activated gene expression in mouse embryonic fibroblasts via Src family kinase.
Heterogeneous surface expression of Thy-1 in fibroblasts modulates inflammation and may thereby modulate injury and repair. As a paradigm, patients with idiopathic pulmonary fibrosis, a disease with pathologic features of chronic inflammation, demonstrate an absence of Thy-1 immunoreactivity within areas of fibrotic activity (fibroblast foci) in contrast to the predominant Thy-1 expressing fibroblasts in the normal lung. Likewise, Thy-1 deficient mice display more severe lung fibrosis in response to an inflammatory injury than wildtype littermates. We investigated the role of Thy-1 in the response of fibroblasts to the pro-inflammatory cytokine TNF-alpha. Our study demonstrates distinct profiles of TNF-alpha-activated gene expression in Thy-1 positive (Thy-1+) and negative (Thy-1-) subsets of mouse embryonic fibroblasts (MEF). TNF-alpha induced a robust activation of MMP-9, ICAM-1, and the IL-8 promoter driven reporter in Thy-1- MEFs, in contrast to only a modest increase in Thy-1+ counterparts. Consistently, ectopic expression of Thy-1 in Thy-1- MEFs significantly attenuated TNF-alpha-activated gene expression. Mechanistically, TNF-alpha activated Src family kinase (SFK) only in Thy-1- MEFs. Blockade of SFK activation abrogated TNF-alpha-activated gene expression in Thy-1- MEFs, whereas restoration of SFK activation rescued the TNF-alpha response in Thy-1+ MEFs. Our findings suggest that Thy-1 down-regulates TNF-alpha-activated gene expression via interfering with SFK- and NF-kappaB-mediated transactivation. The current study provides a novel mechanistic insight to the distinct roles of fibroblast Thy-1 subsets in inflammation.
Shan
Bin
B
Department of Medicine, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America.
Hagood
James S
JS
Zhuo
Ying
Y
Nguyen
Hong T
HT
MacEwen
Mark
M
Morris
Gilbert F
GF
Lasky
Joseph A
JA
D000818:Animals; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism*; D005434:Flow Cytometry; D015151:Immunoblotting; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics; D016209:Interleukin-8 / Q000235:genetics; D020780:Matrix Metalloproteinase 9 / Q000235:genetics; D051379:Mice; D008817:Mice, Mutant Strains; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018800:Thy-1 Antigens / Q000235:genetics / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
D016209:Interleukin-8; D018800:Thy-1 Antigens; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D019061:src-Family Kinases; D020780:Matrix Metalloproteinase 9