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Transcriptomic profiling of peripheral blood mononuclear cells in sarcoidosis and matched controls in A Case Controlled Etiologic Study of Sarcoidosis (ACCESS)

ABSTRACT: Introduction: In sarcoidosis, peripheral lymphopenia and anergy have been associated with increased inflammation and maladaptive immune activity, likely promoting development of chronic and progressive disease. However, the molecular mechanisms that lead to reduced lymphocyte proportions, particularly CD4+ T-cells, have not been fully elucidated. We posit that paradoxical peripheral lymphopenia is characterized by a dysregulated transcriptomic network associated with cell function and fate that results from altered transcription factor targeting activity. Methods: Messenger RNA-sequencing (mRNA-seq) was performed on peripheral blood mononuclear cells (PBMCs) from ACCESS study subjects with sarcoidosis and matched controls and findings validated on a sarcoidosis case-control cohort and a sarcoidosis case series. Preserved PBMC transcriptomic networks between case-control cohorts were assessed to establish cellular associations with gene modules and define regulatory targeting involved in sarcoidosis immune dysregulation utilizing weighted gene co-expression network analysis and differential transcription factor involvement analysis. Network centrality measures identified master transcriptional regulators of subnetworks related to cell proliferation and death. Predictive models of differential PBMC proportions constructed from ACCESS target gene expression corroborated the relationship between aberrant transcription factor regulatory activity and imputed and clinical PBMC populations in the validation cohorts. Results: We identified two unique and preserved gene modules significantly associated with sarcoidosis immune dysregulation. Strikingly, increased expression of a monocyte-driven, and not a lymphocyte-driven, gene module related to innate immunity and cell death was the best predictor of peripheral CD4+ T-cell proportions. Within the gene network of this monocyte-driven module, TLE3 and CBX8 were determined to be master regulators of the cell death subnetwork. A core gene signature of differentially over-expressed target genes of TLE3 and CBX8 involved in cellular communication and immune response regulation accurately predicted imputed and clinical monocyte expansion and CD4+ T-cell depletion. Conclusions: Altered transcriptional regulation associated with aberrant gene expression of a monocyte-driven transcriptional network likely influences lymphocyte function and survival. Although further investigation is warranted, this indicates that crosstalk between hyperactive monocytes and lymphocytes may instigate peripheral lymphopenia and underlie sarcoidosis immune dysregulation and pathogenesis. Future therapies selectively targeting master regulators, or their targets, may mitigate dysregulated immune processes in sarcoidosis and disease progression.

ORGANISM(S): Homo sapiens

PROVIDER: GSE155644 | GEO | 2022/10/14

REPOSITORIES: GEO

ACCESS DATA

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Project description:Rationale: A well-validated animal model of sarcoidosis can help advance our understanding of the pathobiology of this complex disease. We have developed a multiwall carbon nanotube (MWCNT) based murine model that shows marked histological and inflammatory signal similarities to human sarcoidosis. In this study, we compared the alveolar immune cell transcriptional signatures of our murine model with human sarcoidosis to comprehensively assess overlapping molecular programs. Methods: Total RNA was extracted from alveolar macrophages of 6 MWCNT mice and 6 control mice and hybridized to Illumina Mouse WG-6 v2 microarrays. Transcriptional profiling of alveolar immune cells in 15 sarcoidosis patients and 12 healthy humans was previously performed using Affymetrix Human GeneChip U133A 2.0 microarrays. Rigorous statistical methods were used to identify differentially expressed genes. To better elucidate gene expression pathways, integrated network and gene set enrichment analysis (GSEA) were applied. To confirm differential expression of select network genes, we performed qPCR studies using the ABI Prism 7300 Detection. Results: We identified over 1000 genes that were differentially expressed between the control and the MWCNT mice. Gene Ontology functional analysis showed over-representation of processes primarily involved in immunity and inflammation in MCWNT mice. Applying a more comprehensive pathway analysis using GSEA to both mouse and human samples revealed upregulation of 92 gene sets in MWCNT mice and 142 gene sets in sarcoidosis patients. Commonly activated pathways in both MWCNT mice and sarcoidosis included adaptive immunity, T-cell signaling, IL-12/IL-17 signaling and oxidative phosphorylation. Differences in selective gene set enrichment between MWCNT mice and sarcoidosis patients were also observed, among them IL-27 signaling, NK-mediated cytotoxicity and proteasome pathways. We applied network analysis to differentially expressed genes common between the MWCNT model and human sarcoidosis to identify key drivers of disease and putative therapeutic targets. Conclusions: Our MWCNT murine model has an alveolar macrophage signature that varies significantly from control mice. Application of an unbiased transcriptomic approach revealed substantial functional similarities between a murine MWCNT model and human sarcoidosis particularly with respect to activation of immune-specific pathways.

Project description:We hypothesized that patients with sarcoidosis have characteristic mRNA profiles. Microarray analysis of gene expression was done on peripheral blood. Comparing peripheral blood from patients with sarcoidosis to controls, 872 transcripts were upregulated and 1039 were downregulated at >1.5-fold change and a significant q value. Several transcripts associated with interferon and STAT1 were upregulated. Lung and lymph node analyses also showed dramatic increases in STAT1 and STAT1-regulated chemokines. Granulomas in lymph nodes of patients with sarcoidosis expressed abundant STAT1 and phosphorylated STAT1. STAT1 might play an important role in sarcoidosis. This novel hypothesis unites seemingly disparate observations with regard to sarcoidosis including implication of a casual role for interferons, a suspected infectious trigger, TH1 predominating lymphocytes in bronchoalveolar lavage, and the association with hypercalcemia. This study tested the hypothesis that SpA is characterized by a distinct pattern of gene expression in peripheral blood of affected individuals compared with healthy controls. High-density, human GeneChip probe arrays were used to profile mRNA of peripheral blood cells from 18 subjects with SpA and 25 normal individuals. Samples were processed as two separate sets at different times. Blood samples were taken at a time when patients were not receiving systemic immunomodulatory therapy. Differential expression was defined as a 1.5-fold change with a q value <5%. Gene ontology and pathway information were also studied. Signals from 134 probe sets (representing 95 known and 12 unknown gene transcripts) were consistently different from controls in both Sets 1 and 2. Included among these were transcripts for a group of 20 genes, such as interleukin-1 receptors 1 and 2, NLRP2, SLPI, SPARC, and TREM-1 that are clearly related to the immune or inflammatory response and a group of 4 transcripts that have a strong role in bone remodeling. Our observations are the first to implicate SPARC, SLPI, and NLRP2, a component of the innate immune system, in the pathogenesis of SpA. Our results also indicate a possible role for interleukin-1 and its receptors in SpA. In accord with the bone pathology component of SpA, we also found that expression levels of transcripts reflecting bone remodeling factors are also distinguishable in peripheral blood from patients with SpA versus controls. These results confirm some previously identified biomarkers implicated in the pathogenesis of SpA and also point to novel mediators in this disease. Peripheral blood was collected from diseased and control subjects. The sarcoidosis portion of the study included 12 patients and 12 control subjects. The spondyloarthropathy study was done in two independent sets. The first set included 11 patients and the same 12 control subjects used for the sarcoidosis study. The second set included 7 patients and 13 control subjects. For each sample, total RNA was isolated and analyzed by hybridization on Affymetrix arrays.

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Transcriptomic profiling of peripheral blood mononuclear cells in sarcoidosis and matched controls in A Case Controlled Etiologic Study of Sarcoidosis (ACCESS)

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