Agonistic Anti-PDGF Receptor Autoantibodies from Patients with Systemic Sclerosis Impact Human Pulmonary Artery Smooth Muscle Cells Function In Vitro

Abstract

One of the earliest events in the pathogenesis of systemic sclerosis (SSc) is microvasculature damage with intimal hyperplasia and accumulation of cells expressing PDGF receptor. Stimulatory autoantibodies targeting PDGF receptor have been detected in SSc patients and demonstrated to induce fibrosis in vivo and convert in vitro normal fibroblasts into SSc-like cells. Since there is no evidence of the role of anti-PDGF receptor autoantibodies in the pathogenesis of SSc vascular lesions, we investigated the biologic effect of agonistic anti-PDGF receptor autoantibodies from SSc patients on human pulmonary artery smooth muscle cells and the signaling pathways involved. The synthetic (proliferation, migration, and type I collagen gene α1 chain expression) and contractile (smooth muscle-myosin heavy chain and smooth muscle-calponin expression) profiles of human pulmonary artery smooth muscle cells were assessed in vitro after incubation with SSc anti-PDGF receptors stimulatory autoantibodies. The role of reactive oxygen species, NOX isoforms, and mammalian target of rapamycin (mTOR) was investigated. Human pulmonary artery smooth muscle cells acquired a synthetic phenotype characterized by higher growth rate, migratory activity, gene expression of type I collagen α1 chain, and less expression of markers characteristic of the contractile phenotype such as smooth muscle-myosin heavy chain and smooth muscle-calponin when stimulated with PDGF and autoantibodies against PDGF receptor, but not with normal IgG. This phenotypic profile is mediated by increased generation of reactive oxygen species and expression of NOX4 and mTORC1. Our data indicate that agonistic anti-PDGF receptor autoantibodies may contribute to the pathogenesis of SSc intimal hyperplasia.

IL‑33 notably inhibits the growth of colon cancer cells

“…The IL-33 receptor consists of the heterodimeric complex of ST2 and the IL-1 receptor accessory protein, the former of which has been determined to be selectively expressed in Th2 immune responses ( 3 ). Additionally, recent studies have determined a higher prevalence in the development of colorectal cancer amongst patients with inflammatory bowel disease, which appeared to be mediated, at least partially, by elevated levels of IL-33 and ST2 expression under the inflammatory state of the disease ( 8 , 9 , 11 , 21 , 22 ). A previous study determined an association between increased IL-33 expression and increased angiogenesis in vivo , indicating that the IL-33 signaling pathway may support carcinogenesis ( 11 ).…”

A Potential Link Between Oxidative Stress and Endothelial-to-Mesenchymal Transition in Systemic Sclerosis

“…Importantly, GKT-137831 was also able to reduce collagen gel contraction as well as expression of alpha-SMA and CCN2 protein overexpression in fibroblasts isolated from dermal lesions in SSc patients ( 41 ). A NOX4-derived increase of ROS has also been reported to be involved in the vascular smooth muscle cells contractile to synthetic phenotype switch elicited by agonistic anti-PDGF receptor autoantibodies from SSc patients ( 69 ) Taken together, these findings indicate that the NOX system, in addition to ROS production, mediates the activation of collagen synthesis and profibrotic genes.…”

Involvement of platelet‐derived growth factor ligands and receptors in tumorigenesis

“…Trade name Target Type of tumour Imatinib Glivec Abl, PDGFRs, Kit CML, GIST beneficial effect may also involve inhibition of other kinases than those of PDGF receptors. It has been suggested that systemic sclerosis is promoted by activating autoantibodies against PDGFRa found in the serum of patients [97][98][99]; however, this observation has been questioned in other studies [100][101][102].…”