Severe hyperhomocysteinemia is associated with endothelial cell injury that may contribute to an increased incidence of thromboembolic disease. In this study, homocysteine induced programmed cell death in human umbilical vein endothelial cells as measured by TdTmediated dUTP nick end labeling assay, DNA ladder formation, induction of caspase 3-like activity, and cleavage of procaspase 3. Homocysteine-induced cell death was specific to homocysteine, was not mediated by oxidative stress, and was mimicked by inducers of the unfolded protein response (UPR), a signal transduction pathway activated by the accumulation of unfolded proteins in the lumen of the endoplasmic reticulum. Dominant negative forms of the endoplasmic reticulum-resident protein kinases IRE1␣ and -, which function as signal transducers of the UPR, prevented the activation of glucose-regulated protein 78/immunoglobulin chain-binding protein and C/EBP homologous protein/growth arrest and DNA damage-inducible protein 153 in response to homocysteine. Furthermore, overexpression of the point mutants of IRE1 with defective RNase more effectively suppressed the cell death than the kinase-defective mutant. These results indicate that homocysteine induces apoptosis in human umbilical vein endothelial cells by activation of the UPR and is signaled through IRE1. The studies implicate that the UPR may cause endothelial cell injury associated with severe hyperhomocysteinemia.
Coronavirus disease 2019 (COVID-19) is an emerging infectious disease that was first reported in Wuhan, People's Republic of China, and has subsequently spread worldwide. Clinical information on patients who contracted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the perioperative period is limited. Here, we report seven cases with confirmed SARS-CoV-2 infection in the perioperative period of lung resection. Retrospective analysis suggested that one patient had been infected with the SARS-CoV-2 infection before the surgery and the other six patients contracted the infection after the lung resection. Fever, lymphopenia, and ground-glass opacities revealed on computed tomography are the most common clinical manifestations of the patients who contracted COVID-19 after the lung resection. Pathologic studies of the specimens of these seven patients were performed. Pathologic examination of patient 1, who was infected with the SARS-CoV-2 infection before the surgery, revealed that apart from the tumor, there was a wide range of interstitial inflammation with plasma cell and macrophage infiltration. High density of macrophages and foam cells in the alveolar cavities, but no obvious proliferation of pneumocyte, was found. Three of seven patients died from COVID-19 pneumonia, suggesting lung resection surgery might be a risk factor for death in patients with COVID-19 in the perioperative period.
IFN-γ plays a crucial role in anti-tumor responses and also induces expression of PD-L1, a well-established inhibitor of anti-tumor immune function. Understanding how molecular signaling regulates the function of IFN-γ might improve its anti-tumor efficacy. Here, we show that the tumor expression of IFN-γ expression alone has no significant prognostic value in patients with locally advanced lung adenocarcinoma. Surprisingly, patients with tumors expressing both IFN-γ and PD-L1 have the best prognosis compared to those with tumors expressing IFN-γ or PD-L1 alone. Transcriptome analysis demonstrated that tumor tissues expressing IFN-γ display gene expression associated with suppressed cell cycle progression and expansion. Unexpectedly this profile was observed in PD-L1 but not PD-L1- tumors. The current concept is that PD-L1 functions as a shield protecting tumor cells from cytolytic T cell (CTL)-mediated anti-tumor progression. However, our data indicate that PD-L1 expression in the presence of IFN-γ might serve as biomarker for the sensitivity of tumors to the inhibitory effect of IFN-γ. Mechanistic analysis revealed that in lung adenocarcinoma cells IFN-γ-induced activation of JAK2-STAT1 and PI3K-AKT pathways. The activation of JAK2-STAT1 is responsible for the anti-proliferative effect of IFN-γ. Inhibition of PI3K downregulated PD-L1 expression and enhanced the anti-proliferative effect of IFN-γ, suggesting that blockade of PI3K might maximize the IFN-γ-mediated anti-tumor effect. Our findings provide evidence for crosstalk between JAK2-STAT1 and PI3K-AKT pathways in response to IFN-γ in lung adenocarcinoma and have implications for the design of combinatorial targeted therapy and immunotherapy for the treatment of lung adenocarcinoma.
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