Dysfunctional Sars-CoV-2-M protein-specific cytotoxic T lymphocytes in patients recovering from severe COVID-19.

Although the importance of virus-specific cytotoxic T lymphocytes (CTL) in virus clearance is evident in COVID-19, the characteristics of virus-specific CTLs related to disease severity have not been fully explored. Here we show that the phenotype of virus-specific CTLs against immunoprevalent epitopes in COVID-19 convalescents might differ according to the course of the disease. We establish a cellular screening method that uses artificial antigen presenting cells, expressing HLA-A*24:02, the costimulatory molecule 4-1BBL, SARS-CoV-2 structural proteins S, M, and N and non-structural proteins ORF3a and nsp6/ORF1a. The screen implicates SARS-CoV-2 M protein as a frequent target of IFNγ secreting CD8+ T cells, and identifies M198-206 as an immunoprevalent epitope in our cohort of HLA-A*24:02 positive convalescent COVID-19 patients recovering from mild, moderate and severe disease. Further exploration of M198-206-specific CD8+ T cells with single cell RNA sequencing reveals public TCRs in virus-specific CD8+ T cells, and shows an exhausted phenotype with less differentiated status in cells from the severe group compared to cells from the moderate group. In summary, this study describes a method to identify T cell epitopes, indicate that dysfunction of virus-specific CTLs might be an important determinant of clinical outcomes.

Protective effects of EGCg or GCg, a green tea catechin epimer, against postischemic myocardial dysfunction in guinea-pig hearts.

The protective effects of (-)-epigallocatechin-3-gallate (EGCg) or the C-2 epimer, (-)-gallocatechin-3-gallate (GCg), afforded by their antioxidative activity among green tea catechins were investigated in perfused guinea-pig Langendorff hearts subjected to ischemia and reperfusion. The recovery (%) of the left ventricular developed pressure from ischemia by reperfusion was 34.4% in the control, while in the presence of EGCg (3x10(-5) M) or GCg (3x10(-6) M, a more diluted concentration than that of EGCg), it led to a maximal increase of 78.4% or 76.2%, consistent with a significant preservative effect on the tissue level of ATP at the end of ischemia or reperfusion. In the perfused preparation of mitochondria, EGCg (10(-5) M) inhibited mitochondrial Ca(2+) elevation by changes in the Ca(2+) content or the acidification of perfusate, similarly to findings with cyclosporin A, a well known inhibitor of the mitochondrial permeability transition pore. By in vitro electron paramagnetic resonance (EPR), EGCg or GCg was found to directly quench the activity of active oxygen radicals, with the strongest activity in tea catechins. EGCg or GCg decreased the caspase-3 activity induced apoptosis. Therefore, it is concluded that the beneficial effects of EGCg or GCg play an important role in ischemia-reperfusion hearts in close relation with nitric oxide (NO), active oxygen radicals and biological redox systems in mitochondria.

Influence of coronary artery disease on operative mortality and long-term survival after abdominal aortic aneurysm repair.

PURPOSE: This retrospective study was conducted to evaluate the effects of coronary artery disease (CAD) on short- and long-term survival after abdominal aortic aneurysm (AAA) repair. METHODS: One hundred consecutive patients underwent elective AAA repair between 1991 and 2002. Coronary angiography was performed in all patients, revealing significant coronary artery lesions in 47 (47%). Percutaneous transluminal coronary angioplasty (PTCA) was performed in 11 patients, 20 (median) days before the abdominal surgery. Abdominal aortic aneurysm repair was performed 60 (median) days after coronary artery bypass grafting (CABG) in five patients, and both procedures were performed simultaneously in two patients. RESULTS: The in-hospital mortality rate for AAA repair was 1.0%, but there was no cardiac-related operative morbidity or mortality. The 96 patients discharged were followed up for a mean period of 2.9 years (range 3-143 months). The cumulative survival rates after 1, 2, 3, and 5 years were 98%, 95%, 88%, and 77%, respectively. Only one patient (1%) died of myocardial infarction. There was no significant difference in the long-term survival of the CAD and non-CAD patients. CONCLUSIONS: These results emphasize the importance of routine coronary angiography and subsequent coronary revascularization to improve early and late survival rates after AAA repair.