Dysfunctional immune response in the COVID-19 patients is a recurrent theme impacting symptoms and mortality, yet the detailed understanding of pertinent immune cells is not complete. We applied single-cell RNA sequencing to 284 samples from 196 COVID-19 patients and controls and created a comprehensive immune landscape with 1.46 million cells. The large dataset enabled us to identify that different peripheral immune subtype changes were associated with distinct clinical features including age, sex, severity, and disease stages of COVID-19. SARS-CoV-2 RNAs were found in diverse epithelial and immune cell types, accompanied by dramatic transcriptomic changes within viral positive cells. Systemic up-regulation of S100A8/A9, mainly by megakaryocytes and monocytes in the peripheral blood, may contribute to the cytokine storms frequently observed in severe patients. Our data provide a rich resource for understanding the pathogenesis and developing effective therapeutic strategies for COVID-19.

Background: Accumulating evidence proposed Janus-associated kinase (JAK) inhibitors as therapeutic targets warranting rapid investigation. Objective: This study evaluated the efficacy and safety of ruxolitinib, a JAK1/2 inhibitor, for coronavirus disease 2019. Methods: We conducted a prospective, multicenter, single-blind, randomized controlled phase II trial involving patients with severe coronavirus disease 2019. Results: Forty-three patients were randomly assigned (1:1) to receive ruxolitinib plus standard-of-care treatment (22 patients) or placebo based on standard-of-care treatment (21 patients). After exclusion of 2 patients (1 ineligible, 1 consent withdrawn) from the ruxolitinib group, 20 patients in the intervention group and 21 patients in the control group were included in the study. Treatment with ruxolitinib plus standard-of-care was not associated with significantly accelerated clinical improvement in severe patients with coronavirus disease 2019, although ruxolitinib recipients had a numerically faster clinical improvement. Eighteen (90%) patients from the ruxolitinib group showed computed tomography improvement at day 14 compared with 13 (61.9%) patients from the control group (P 5 .0495). Three patients in the control group died of respiratory failure, with 14.3% overall mortality at day 28; no patients died in the ruxolitinib group. Ruxolitinib was well tolerated with low toxicities and no new safety signals. Levels of 7 cytokines were significantly decreased in the ruxolitinib group in comparison to the control group. Conclusions: Although no statistical difference was observed, ruxolitinib recipients had a numerically faster clinical improvement. Significant chest computed tomography improvement, a faster recovery from lymphopenia, and favorable side-effect profile in the ruxolitinib group were encouraging and informative to future trials to test efficacy of ruxolitinib in a larger population. (

COVID-19 is a disease with heterogeneous clinical appearances. Most patients are asymptomatic or exhibit mild to moderate symptoms; approximately 15% progress to severe pneumonia and about 5% are eventually admitted to the intensive care unit (ICU) due to acute respiratory distress syndrome (ARDS), septic shock and/ or multiple organ failure. ICU patients respond poorly to currently available treatments and exhibit a high mortality rate. 1-3 Inadequate identification of the determinants of fatal outcomes is one of the major obstacles to the improvement of the outcomes in severe COVID-19 patients. A previous study reported a scoring system (COVID-GRAM) which accurately predicted the occurrence of critical illness in hospitalized COVID-19 patients. 4 Damage-associated molecular patterns (DAMPs), or alarmins, are a number of molecules, released by stressed cells undergoing microbial infection or sterile injury, that act as danger signals to promote and exacerbate the inflammatory response. 5,6 Of note, the serum level of S100A8/A9 and HMGB1 was found to be correlated with both the severity of pathogen-associated tissue damage and excessive cytokine storm. 7 Despite the hypothesis that S100A8/A9 and HMGB1 are significantly involved in COVID-19, so far, no study has yet tried to substantiate the hypothesis. In this study, we aimed to define the role of S100A8/ A9 and HMGB1 in progression to a fatal outcome and develop clinically relevant risk strata for COVID-19 patients. A total of 121 patients were enrolled in this retrospective study, of which 40 patients were in ICU and 81 patients in general wards at enrollment (Table S1). ICU Patients had much higher COVID-GRAM risk scores in comparison to those in general wards. Complications, including ARDS, sepsis, septic shock, secondary infection, acute renal injury, acute cardiac injury or failure, were more frequent in CCOVID-19 patients admitted to ICU. As of the cutoff date of April 30, 2020, most of non-ICU patients (96.3%) had been discharged alive, while 82.5% of ICU patients had died in ICU.