Dysfunctional phenotype of systemic and pulmonary regulatory T cells associate with lethal COVID-19 cases.

Severe cases of COVID-19 present hyperinflammatory condition that can be fatal. Little is known about the role of regulatory responses in SARS-CoV-2 infection. In this study, we evaluated the phenotype of regulatory T cells in the blood (peripheral blood mononuclear cell) and the lungs (broncho-alveolar) of adult patients with severe COVID-19 under invasive mechanical ventilation. Our results show important dynamic variation on Treg cells phenotype during COVID-19 with changes in number and functional parameters from the day of intubation (Day 1 of intensive care unit admission) to Day 7. We observed that compared with surviving patients, non-survivors presented lower numbers of Treg cells in the blood. In addition, lung Tregs of non-survivors also displayed higher PD1 and lower FOXP3 expressions suggesting dysfunctional phenotype. Further signs of Treg dysregulation were observed in non-survivors such as limited production of IL-10 in the lungs and higher production of IL-17A in the blood and in the lungs, which were associated with increased PD1 expression. These findings were also associated with lower pulmonary levels of Treg-stimulating factors like TNF and IL-2. Tregs in the blood and lungs are profoundly dysfunctional in non-surviving COVID-19 patients.

Lung Ultrasound Can Predict the Clinical Course and Severity of COVID-19 Disease.

Coronavirus disease 2019 (COVID-19) compromises the lung in large numbers of people. The development of minimally invasive methods to determine the severity of pulmonary extension is desired. This study aimed to describe the characteristics of sequential lung ultrasound and to test the prognostic usefulness of this exam in a group of patients admitted to the hospital with COVID-19. We prospectively evaluated patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection admitted to our hospital between April and August 2020. Bedside lung ultrasound exams were performed at three time points: at inclusion in the study, after 48 h and on the seventh day of follow-up. Lung ultrasound scores were quantified according to the aeration loss in each of eight zones scanned. Sixty-six participants were included: 42 (63.6%) in the intensive care unit and 24 (36.3%) in the ward. Lung ultrasound scores were higher in participants admitted to the intensive care unit than in those admitted to the ward at the time of inclusion (16 [13-17] vs. 10 [4-14], p < 0.001), after 48 h (15.5 [13-17] vs. 12.5 [8.2-14.7], p = 0.001) and on the seventh day (16 [14-17] vs. 7 [4.5-13.7], p < 0.001) respectively. Lung ultrasound score measured at the time of inclusion in the study was independently associated with the need for admission to the intensive care unit (odds ratio = 1.480; 95% confidence interval, 1.093-2.004; p = 0.011) adjusted by the Sequential Organ Failure Assessment score.