Vaccination with Flt3L-induced CD8α+ dendritic cells prevents CD4+ T helper cell-mediated experimental autoimmune myocarditis

Experimental autoimmune myocarditis (EAM) represents a CD4(+) T helper (Th) cell-mediated mouse model of inflammatory heart disease. Interferon (IFN)-γ, typically produced by Th1 cells, reduces EAM severity in myosin heavy-chain-(MyHC)-α peptide/Complete Freund adjuvant-immunized mice. Thus, developing a vaccination strategy that promotes differentiation of Th1 cells may be beneficial in EAM. FMS-like tyrosine kinase 3 ligand (Flt3L)-induced splenic CD8α(+) dendritic cells (DC), which produce interleukin (IL)-12p35, were identified to selectively induce biased differentiation towards Th1. Mice vaccinated with MyHC-α-loaded Flt3L-induced splenic CD8α(+) DC were protected from EAM. In contrast, when Flt3L-induced splenic CD8α(+) DC were pre-stimulated and over-activated with LPS and αCD40 antibodies or loaded with unspecific OVA(323-339) peptide instead of MyHC-α peptide, mice developed similar disease scores as non-vaccinated controls. Vaccination efficacy depended on IFN-γ, since CD8α(+)-vaccinated IFN-γR(-/-) mice were not protected. Importantly, splenic CD8α(+) vaccination was independent of regulatory T cells. Taken together, Flt3L-induced dendritic cell-based antigen-specific vaccination limits expansion of auto-reactive Th cells and protects mice from autoimmune heart inflammation

The adapter protein c-Cbl-associated protein (CAP) protects from acute CVB3-mediated myocarditis through stabilization of type I interferon production and reduced cytotoxicity

c-Cbl-associated protein (CAP), also called Sorbs1 or ponsin, has been described as an essential adapter protein in the insulin-signalling pathway. Here, we describe for the first time a unique protective role for CAP in viral myocarditis. Mortality and heart failure development were increased in CAP−/− mice compared to CAP+/+ littermates after Coxsackievirus (CVB3) infection. Mechanistically, CAP protected from tissue apoptosis because of reduced CD8+ T and natural killer cell cytotoxicity. Despite reduced cytotoxic elimination of CVB3-infected cells in CAP+/+ hearts, however, CAP enhanced interferon regulatory factor 3(IRF3)-dependent antiviral type I interferon production and decreased viral proliferation in vitro by binding to the cytoplasmic RIG-I-like receptor melanoma differentiation-associated protein 5 (MDA5). Taken together, these findings reveal a novel modulatory role for CAP in the heart as a key protein stabilizing antiviral type I interferon production, while protecting from excessive cytotoxic responses. Our study will help to define future strategies to develop treatments to limit detrimental responses during viral heart inflammation

Combining blood glucose and SpO2/FiO2 ratio facilitates prediction of imminent ventilatory needs in emergency room COVID-19 patients

Abstract The increasing requirement of mechanical ventilation (MV) due to the novel coronavirus disease (COVID-19) is still a global threat. The aim of this study is to identify markers that can easily stratify the impending use of MV in the emergency room (ER). A total of 106 patients with COVID-19 requiring oxygen support were enrolled. Fifty-nine patients were provided MV 0.5 h (interquartile range: 0.3 to 1.4) post-admission. Clinical and laboratory data before intubation were collected. Using a multivariate logistic regression model, we identified four markers associated with the impending use of MV, including the ratio of peripheral blood oxygen saturation to fraction of inspired oxygen (SpO2/FiO2 ratio), alanine aminotransferase, blood glucose (BG), and lymphocyte counts. Among these markers, SpO2/FiO2 ratio and BG, which can be measured easily and immediately, showed higher accuracy (AUC: 0.88) than SpO2/FiO2 ratio alone (AUC: 0.84), despite no significant difference (DeLong test: P = 0.591). Moreover, even in patients without severe respiratory failure (SpO2/FiO2 ratio > 300), BG (> 138 mg/dL) was predictive of MV use. Measuring BG and SpO2/FiO2 ratio may be a simple and versatile new strategy to accurately identify ER patients with COVID-19 at high risk for the imminent need of MV

The adapter protein c-Cbl-associated protein (CAP) protects from acute CVB3-mediated myocarditis through stabilization of type I interferon production and reduced cytotoxicity

c-Cbl-associated protein (CAP), also called Sorbs1 or ponsin, has been described as an essential adapter protein in the insulin-signalling pathway. Here, we describe for the first time a unique protective role for CAP in viral myocarditis. Mortality and heart failure development were increased in CAP−/− mice compared to CAP+/+ littermates after Coxsackievirus (CVB3) infection. Mechanistically, CAP protected from tissue apoptosis because of reduced CD8+ T and natural killer cell cytotoxicity. Despite reduced cytotoxic elimination of CVB3-infected cells in CAP+/+ hearts, however, CAP enhanced interferon regulatory factor 3(IRF3)-dependent antiviral type I interferon production and decreased viral proliferation in vitro by binding to the cytoplasmic RIG-I-like receptor melanoma differentiation-associated protein 5 (MDA5). Taken together, these findings reveal a novel modulatory role for CAP in the heart as a key protein stabilizing antiviral type I interferon production, while protecting from excessive cytotoxic responses. Our study will help to define future strategies to develop treatments to limit detrimental responses during viral heart inflammation

Early alveolar epithelial cell necrosis is a potential driver of COVID-19-induced acute respiratory distress syndrome

Summary: Acute respiratory distress syndrome (ARDS) with COVID-19 is aggravated by hyperinflammatory responses even after the peak of the viral load has passed; however, its underlying mechanisms remain unclear. In the present study, analysis of the alveolar tissue injury markers and epithelial cell death markers in patients with COVID-19 revealed that COVID-19-induced ARDS was characterized by alveolar epithelial necrosis at an early disease stage. Serum levels of HMGB-1, one of the DAMPs released from necrotic cells, were also significantly elevated in these patients. Further analysis using a mouse model mimicking COVID-19-induced ARDS showed that the alveolar epithelial cell necrosis involved two forms of programmed necrosis, namely necroptosis, and pyroptosis. Finally, the neutralization of HMGB-1 attenuated alveolar tissue injury in the mouse model. Collectively, necrosis, including necroptosis and pyroptosis, is the predominant form of alveolar epithelial cell death at an early disease stage and subsequent release of DAMPs is a potential driver of COVID-19-induced ARDS