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Molecular characterization of systemic sclerosis esophageal pathology identifies inflammatory and proliferative signatures

ABSTRACT: Esophageal involvement in patients with systemic sclerosis (SSc) is common, but tissue-specific pathological mechanisms are poorly understood. Fibrosis in the esophagus is thought to disrupt smooth muscle function and lead to esophageal dilatation, but autopsy studies demonstrate esophageal smooth muscle atrophy and the absence of fibrosis in the majority of SSc cases. Molecular characterization of SSc esophageal pathology is lacking. Herein, we perform a detailed characterization of SSc esophageal histopathology and molecular signatures at the level of gene expression. Esophageal biopsies were prospectively obtained during esophagogastroduodenoscopy in 16 consecutive SSc patients and 7 subjects without SSc. Upper and lower esophageal biopsies were evaluated for histopathology and gene expression. Individual patient’s upper and lower esophageal biopsies showed nearly identical patterns of gene expression. Similar to skin, inflammatory and proliferative gene expression signatures were identified suggesting that molecular subsets are a universal feature of SSc end-target organ pathology. The inflammatory signature was present in biopsies without high numbers of infiltrating lymphocytes. Molecular classification of esophageal biopsies was independent of SSc skin subtype, serum autoantibodies and esophagitis. Proliferative and inflammatory molecular gene expression subsets in tissues from patients with SSc may be a conserved, reproducible component of SSc pathogenesis. The inflammatory signature is observed in biopsies that lack large inflammatory infiltrates suggesting that immune activation is a major driver of SSc esophageal pathogenesis.

ORGANISM(S): Homo sapiens

PROVIDER: GSE68698 | GEO | 2015/10/19

SECONDARY ACCESSION(S): PRJNA283411

REPOSITORIES: GEO

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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'.

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Molecular characterization of systemic sclerosis esophageal pathology identifies inflammatory and proliferative signatures

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