Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Increased Cell Surface Fas Expression is Necessary to Sensitize Lung Fibroblasts to Fas Ligation-Induced Apoptosis: Implications for Fibroblast Accumulation in Idiopathic Pulmonary Fibrosis.

ABSTRACT: Idiopathic pulmonary fibrosis (IPF) is associated with the accumulation of collagen-secreting fibroblasts and myofibroblasts in the lung parenchyma. Many mechanisms contribute to their accumulation, including resistance to apoptosis. In previous work, we showed that exposure to the pro-inflammatory cytokines, TNF-α and IFN-γ reverses fibroblast resistance to apoptosis. The goal of this study was to investigate the underlying mechanism. Based on an initial interrogation of the transcriptomes of unstimulated and TNF-α and IFN-γ-stimulated primary lung fibroblasts and the lung fibroblast cell line, MRC5, we show here that among Fas-signaling pathway molecules, Fas expression was increased ~6-fold in an NF-κB and p38mapk-dependent fashion. Prevention of the increase in Fas expression using Fas siRNAs blocked the ability of TNF-α and IFN-γ to sensitize fibroblasts to Fas ligation induced-apoptosis; while enforced adenovirus-mediated Fas overexpression was sufficient to overcome basal resistance to Fas-induced apoptosis. Examination of lung tissues from IPF patients revealed low to absent staining of Fas in fibroblastic cells of fibroblast foci. Collectively, these findings suggest that increased expression of Fas is necessary and sufficient to overcome the resistance of lung fibroblasts to Fas-induced apoptosis. They also suggest that approaches aimed at increasing Fas expression by lung fibroblasts and myofibroblasts may be therapeutically relevant. To investigate the mechanism by which TNF-α and IFN-γ reprogram fibroblasts from resistance to sensitivity to Fas-ligation-induce apoptosis, we exposed human primary lung fibroblasts from an IPF patient (FS087) and non-disease control subject (N78) and the human fetal lung fibroblast cell lung (MRC-5) to TNF-α (10 ng/ml) and IFN-γ (50 U/ml) for 36 hr and analyzed changes in their transcriptomes using Affymetrix microarrays.

ORGANISM(S): Homo sapiens

SUBMITTER: Michael Edwards

PROVIDER: E-GEOD-26594 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:COVID-19 has rapidly circulated around the globe and caused significant morbidity and mortality. The disease is characterized by excessive production of pro-inflammatory cytokines and acute lung damage and patient mortality. Although initial cytokine cascades may be beneficial to the host for clearing the virus, enhanced production of pro-inflammatory cytokines and increasing levels in the systemic circulation, referred to as cytokine storm, can promote tissue damage by inducing inflammatory cell death in both infected and bystander cells. Of the multiple inflammatory cytokines produced by innate immune cells during SARS-CoV-2 infection, we found that the combination of TNF-α and IFN-γ specifically induced cell death characterized by GSDME¬–mediated pyroptosis, caspase-8–mediated apoptosis, and MLKL–mediated necroptosis. Cells deficient in both RIPK3 and caspase-8 or RIPK3 and FADD were resistant to this cell death. However, deletion of pyroptosis, apoptosis, or necroptosis individually was not sufficient to protect against cell death. Mechanistically, the STAT1/IRF1 axis activated by TNF-α and IFN-γ co-treatment induced iNOS for the production of nitric oxide. Pharmacological and genetic deletion of this pathway inhibited pyroptosis, apoptosis, and necroptosis in macrophages. Moreover, inhibition of inflammatory cell death protected mice from TNF-α and IFN-γ–induced lethal cytokine shock that mirrors the pathological symptoms of COVID-19. To determine the physiological relevance of protection, we neutralized both TNF-α and IFN-γ in multiple disease models associated with cytokine storm and found that this treatment provided substantial protection against not only SARS-CoV-2 infection, but also sepsis, hemophagocytic lymphohistiocytosis, and cytokine shock models. Collectively, our findings reveal that blocking the COVID-19 cytokine-mediated inflammatory cell death signaling pathway identified in this study may benefit patients with COVID-19 or other cytokine storm-driven syndromes by limiting inflammation and tissue damage. Additionally, these results open new avenues for the treatment of other infectious and autoinflammatory diseases and cancer where TNF-α and IFN-γ synergism play key pathological roles.

Dataset Information

Increased Cell Surface Fas Expression is Necessary to Sensitize Lung Fibroblasts to Fas Ligation-Induced Apoptosis: Implications for Fibroblast Accumulation in Idiopathic Pulmonary Fibrosis.

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