Project description:Autoantibodies (Aab) are frequent in systemic sclerosis (SSc). While recognized as potent biomarkers, their pathogenic role is much debated. This study explored the effect of purified IgG from SSc patients on the phenotype and function of healthy dermal fibroblast (FB) using an innovative multi-omics approach.
Project description:Pathway expression analysis in systemic sclerosis revealed key mediators driving pathology within each of the intrinsic gene expression subsets. Genome-wide expression profiling in systemic sclerosis (SSc) has identified four 'intrinsic' subsets of disease (fibroproliferative, inflammatory, limited, and normal-like), each of which appear to be driven by distinct signaling pathways. Here we examine experimentally derived gene expression signatures for thirteen agonists to better understand the molecular mechanisms underlying each intrinsic subsets. Pathway-specific gene signatures were compared against skin biopsy microarray data consisting of 329 microarray hybridizations from 287 unique biopsies representing 111 patients. Hierarchical clustering recapitulated the four SSc 'intrinsic' gene expression subsets, along with an intermediate subset exhibiting both inflammatory and fibroproliferative gene expression signatures. The fibroproliferative subset is most strongly associated with the PDGF gene signature, while the inflammatory subset demonstrated strong activation of NF-kappaB, characterized by early induction of TH2 signals, which transitions to a more TH17-like immune response over time. The limited subset was associated with IFNalpha signaling, combined with strong downregulation of PDGF signaling. The inflammatory-proliferative subset shows downregulation of NF-kappaB-associated pathways in conjunction with increased PDGF signaling, suggestive of a transitional state linking the inflammatory and fibroproliferative subsets. IL-13 signaling was strongly associated with early disease, while TGFbeta signaling was associated with more severe disease. Together these data suggest a multi-step, progressive model of disease pathogenesis driven by distinct pathways. Targeting these pathways based upon a patient's underlying disease subset should improve therapeutic outcomes. In vitro treatment of human dermal fibroblasts was performed to identify pathway-specific gene signatures. These gene signatures were then compared against systemic sclerosis skin biopsy microarrays to determine the overall contribution of each pathway to disease. This study includes re-analysis of 247 skin biopsy samples from GSE9285, GSE32413, and GSE45485. Links to these Samples are provided below. The re-processed normalized data for these Samples are included in the supplementary file 'GSE56308_247_Skin_Biopsy_Reanalysis_Samples.txt'.
Project description:Systemic sclerosis (SSc) is an autoimmune disease characterized by clinical heterogeneity, multi-organ involvement, and complex genetic risk. Here, we report the first multi-tissue meta-analysis of ten independent SSc gene expression datasets. We identify a common immune-fibrotic expression axis across all tissues that is associated with the most severe disease phenotypes. The coexpression patterns conserved across tissues and phenotypes were used to query functional genomic networks, which allowed us to identify common and tissue-specific disease drivers. We find evidence of pro-fibrotic macrophages (MØs) in SSc end-target organs. Prominent genes in the skin functional genomic network are associated with SSc genetic risk and are modulated by immunosuppressive treatment in clinical improvers. These data suggest the interactions between T lymphocytes and MØs are a critical driver of disease and implicate MØs as central to SSc pathogenesis. In total, this study presents a mechanism for fibrosis in SSc end-target tissues, a set of putative therapeutic targets for modulating SSc, and a framework for multi-tissue functional genomic studies of complex human disease.