Rationale: The coronavirus disease (COVID-19) pandemic is now a global health concern. Objectives: We compared the clinical characteristics, laboratory examinations, computed tomography images, and treatments of patients with COVID-19 from three different cities in China. Methods: A total of 476 patients were recruited from January 1, 2020, to February 15, 2020, at three hospitals in Wuhan, Shanghai, and Anhui. The patients were divided into four groups according to age and into three groups (moderate, severe, and critical) according to the fifth edition of the Guidelines on the Diagnosis and Treatment of COVID-19 issued by the National Health Commission of China. Measurements and Main Results: The incidence of comorbidities was higher in the severe (46.3%) and critical (67.1%) groups than in the moderate group (37.8%). More patients were taking angiotensinconverting enzyme inhibitors/angiotensin II receptor blockers in the moderate group than in the severe and critical groups. More patients had multiple lung lobe involvement and pleural effusion in the critical group than in the moderate group. More patients received antiviral agents within the first 4 days in the moderate group than in the severe group, and more patients received antibiotics and corticosteroids in the critical and severe groups. Patients .75 years old had a significantly lower survival rate than younger patients. Conclusions: Multiple organ dysfunction and impaired immune function were the typical characteristics of patients with severe or critical illness. There was a significant difference in the use of angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers among patients with different severities of disease. Involvement of multiple lung lobes and pleural effusion were associated with the severity of COVID-19. Advanced age (>75 yr) was a risk factor for mortality.

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.

Prolyl hydroxylation is a critical posttranslational modification that affects structure, function, and turnover of target proteins. Prolyl 3-hydroxylation occurs at only one position in the triple-helical domain of fibrillar collagen chains, and its biological significance is unknown. CRTAP shares homology with a family of putative prolyl 3-hydroxylases (P3Hs), but it does not contain their common dioxygenase domain. Loss of Crtap in mice causes an osteochondrodysplasia characterized by severe osteoporosis and decreased osteoid production. CRTAP can form a complex with P3H1 and cyclophilin B (CYPB), and Crtap-/- bone and cartilage collagens show decreased prolyl 3-hydroxylation. Moreover, mutant collagen shows evidence of overmodification, and collagen fibrils in mutant skin have increased diameter consistent with altered fibrillogenesis. In humans, CRTAP mutations are associated with the clinical spectrum of recessive osteogenesis imperfecta, including the type II and VII forms. Hence, dysregulation of prolyl 3-hydroxylation is a mechanism for connective tissue disease.