Project description:A comprehensive understanding of the changes in gene expression in cell types involved in idiopathic pulmonary fibrosis (IPF) will shed light on the mechanisms underlying the loss of alveolar epithelial cells, and development of honeycomb cysts and fibroblastic foci. We sought to understand changes in IPF lung cell transcriptomes and gain insight into innate immune aspects of pathogenesis. We investigated IPF pathogenesis using single cell RNA-sequencing of fresh lung explants, comparing human IPF fibrotic lower lobes reflecting late disease, upper lobes reflecting early disease and normal lungs. IPF lower lobes showed increased fibroblasts, and basal, ciliated, goblet and club cells, but decreased alveolar epithelial cells, and marked alterations in inflammatory cells. We found three discrete macrophage subpopulations in normal and fibrotic lungs, one expressing monocyte markers, one highly expressing FABP4 and INHBA (FABP4hi), and one highly expressing SPP1 and MERTK (SPP1hi). SPP1hi macrophages in fibrotic lower lobes showed highly upregulated SPP1 and MERTK expression. Low-level local proliferation of SPP1hi macrophages in normal lungs was strikingly increased in IPF lungs. Co-localization and causal modeling supported the role for these highly proliferative SPP1hi macrophages in activation of IPF myofibroblasts in lung fibrosis. These data suggest SPP1hi macrophages contribute importantly to lung fibrosis in IPF, and that therapeutic strategies targeting MERTK and macrophage proliferation may show promise for treatment of this disease.
Project description:A comprehensive understanding of the changes in gene expression in cell types involved in idiopathic pulmonary fibrosis (IPF) will shed light on the mechanisms underlying the loss of alveolar epithelial cells and development of honeycomb cysts and fibroblastic foci. We sought to understand changes in IPF lung cell transcriptomes and gain insight into innate immune aspects of pathogenesis.We investigated IPF pathogenesis using single-cell RNA-sequencing of fresh lung explants, comparing human IPF fibrotic lower lobes reflecting late disease, upper lobes reflecting early disease and normal lungs.IPF lower lobes showed increased fibroblasts, and basal, ciliated, goblet and club cells, but decreased alveolar epithelial cells, and marked alterations in inflammatory cells. We found three discrete macrophage subpopulations in normal and fibrotic lungs, one expressing monocyte markers, one highly expressing FABP4 and INHBA (FABP4hi), and one highly expressing SPP1 and MERTK (SPP1hi). SPP1hi macrophages in fibrotic lower lobes showed highly upregulated SPP1 and MERTK expression. Low-level local proliferation of SPP1hi macrophages in normal lungs was strikingly increased in IPF lungs.Co-localisation and causal modelling supported the role for these highly proliferative SPP1hi macrophages in activation of IPF myofibroblasts in lung fibrosis. These data suggest that SPP1hi macrophages contribute importantly to lung fibrosis in IPF, and that therapeutic strategies targeting MERTK and macrophage proliferation may show promise for treatment of this disease.
Project description:Tolerogenic dendritic cells (tol-DCs) offer a promising therapeutic potential for autoimmune diseases. Tol-DCs have been reported to inhibit immunogenic responses, yet little is known about the mechanisms controlling their tolerogenic status, as well as associated specific markers. Here we show that the anti-inflammatory TAM receptor tyrosine kinase MERTK, is highly expressed on clinical grade dexamethasone-induced human tol-DCs and mediates their tolerogenic effect. Neutralization of MERTK in allogenic mixed lymphocyte reactions as well as autologous DC-T cell cultures leads to increased T cell proliferation and IFN-g production. Additionally, we identify a previously unrecognized non-cell autonomous regulatory function of MERTK expressed on DCs. Recombinant Mer-Fc protein, used to mimic MERTK on DCs, suppresses naïve and antigen-specific memory T cell activation. This mechanism is mediated by the neutralization of the MERTK agonist Protein S (PROS1) expressed by T cells. We find that MERTK and PROS1 are expressed in human T cells upon TCR activation and drive an autocrine pro-proliferative mechanism. Collectively, these results suggest that MERTK on tol-DCs directly inhibits T cell activation through the competition for PROS1 interaction with MERTK in the T cells. Targeting MERTK may provide an interesting approach to effectively increase or suppress tolerance for the purpose of immunotherapy. The complete database comprised the expression measurements of 54,675 genes for: immature (n=9), mature (n=7) and tolerogenic (n=8). Influence of treatment with dexamethasone (n=3) and LPS (n=2) are included.
Project description:Rationale: The role of club cells in the pathology of Idiopathic Pulmonary Fibrosis IPF is not well understood. PDIA3, an endoplasmic reticulum (ER) based redox chaperone catalyzes the cysteine disulfide bonds (-S-S-) in various fibrosis-related proteins; however, mechanisms of action of PDIA3 in pulmonary fibrosis is not fully elucidated. Objectives: To examine the role of club cells and PDIA3 in the pathogenesis of pulmonary fibrosis (PF) and therapeutic potential of inhibition of PDIA3 in PF. Methods: The impact of PDIA3 and aberrant club cells in PF was studied by retrospective analysis of human transcriptome data from LGRC, and specific deletion and inhibition of PDIA3 in club cells and blocking Osteopontin (SPP1) downstream of PDIA3 in mice. Measurements and Main Results: The PDIA3 along with club cell secretory protein (SCGB1A1 or CCSP) signatures are upregulated in IPF compared to control patients, and PDIA3 increases correlate with a decrease in lung function in IPF patients. The Bleomycin (BLM) model of PF showed increases in aberrant CCSP and PDIA3 positive cells in the lung parenchyma. Ablation of Pdia3, specifically in CCSP cells, decreases CCSP cells along with PF in mice. The therapeutic administration of a PDI inhibitor LOC14 reversed the BLM-induced CCSP cells and PF in mice. The proteomic screen of the PDIA3 partners revealed SPP1 as a major interactor in PF. Blocking SPP1 attenuated the development of PF in mice. Conclusions: Collectively, this study demonstrates a new relationship of club cells, with PDIA3, SPP1, and a putative pathological function of club cells in pulmonary fibrosis.
Project description:Whole transcriptome RNA-seq analysis to measure group-wise RNA expression level of the MERTK gene in 3 healthy controls (known to be homozygous non-risk haplotype at MERTK gene locus) and to compare this to the group-wise RNA expression level of the MERTK gene in 5 Multiple Sclerosis-affected (MS-affected) individuals (known to be homozygous for the MS risk haplotype at the MERTK gene locus). We sequenced the whole transcriptome of 3 healthy control samples which were all homozygous for the MS non-risk haplotype at the MERTK gene. We also did the same RNA-seq protocol on 5 MS-affected subjects that were all homozygous for the Risk haplotype at the MERTK gene. All 8 samples were sequenced evenly across 3 lanes of an Illumina HiSeq NGS machine to remove any batch-type effects that could be caused by sequencing e.g. all cases in one lane and all controls in another lane.
Project description:Tolerogenic dendritic cells (tol-DCs) offer a promising therapeutic potential for autoimmune diseases. Tol-DCs have been reported to inhibit immunogenic responses, yet little is known about the mechanisms controlling their tolerogenic status, as well as associated specific markers. Here we show that the anti-inflammatory TAM receptor tyrosine kinase MERTK, is highly expressed on clinical grade dexamethasone-induced human tol-DCs and mediates their tolerogenic effect. Neutralization of MERTK in allogenic mixed lymphocyte reactions as well as autologous DC-T cell cultures leads to increased T cell proliferation and IFN-g production. Additionally, we identify a previously unrecognized non-cell autonomous regulatory function of MERTK expressed on DCs. Recombinant Mer-Fc protein, used to mimic MERTK on DCs, suppresses naïve and antigen-specific memory T cell activation. This mechanism is mediated by the neutralization of the MERTK agonist Protein S (PROS1) expressed by T cells. We find that MERTK and PROS1 are expressed in human T cells upon TCR activation and drive an autocrine pro-proliferative mechanism. Collectively, these results suggest that MERTK on tol-DCs directly inhibits T cell activation through the competition for PROS1 interaction with MERTK in the T cells. Targeting MERTK may provide an interesting approach to effectively increase or suppress tolerance for the purpose of immunotherapy.
Project description:Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and highly lethal lung disease with unknown etiology and poor prognosis.