Background An important feature of severe acute respiratory syndrome coronavirus 2 pathogenesis is COVID-19associated coagulopathy, characterised by increased thrombotic and microvascular complications. Previous studies have suggested a role for endothelial cell injury in COVID-19-associated coagulopathy. To determine whether endotheliopathy is involved in COVID-19-associated coagulopathy pathogenesis, we assessed markers of endothelial cell and platelet activation in critically and non-critically ill patients admitted to the hospital with COVID-19. Methods In this single-centre cross-sectional study, hospitalised adult (≥18 years) patients with laboratory-confirmed COVID-19 were identified in the medical intensive care unit (ICU) or a specialised non-ICU COVID-19 floor in our hospital. Asymptomatic, non-hospitalised controls were recruited as a comparator group for biomarkers that did not have a reference range. We assessed markers of endothelial cell and platelet activation, including von Willebrand Factor (VWF) antigen, soluble thrombomodulin, soluble P-selectin, and soluble CD40 ligand, as well as coagulation factors, endogenous anticoagulants, and fibrinolytic enzymes. We compared the level of each marker in ICU patients, non-ICU patients, and controls, where applicable. We assessed correlations between these laboratory results with clinical outcomes, including hospital discharge and mortality. Kaplan-Meier analysis was used to further explore the association between biochemical markers and survival. Findings 68 patients with COVID-19 were included in the study from April 13 to April 24, 2020, including 48 ICU and 20 non-ICU patients, as well as 13 non-hospitalised, asymptomatic controls. Markers of endothelial cell and platelet activation were significantly elevated in ICU patients compared with non-ICU patients, including VWF antigen (mean 565% [SD 199] in ICU patients vs 278% [133] in non-ICU patients; p<0•0001) and soluble P-selectin (15•9 ng/mL [4•8] vs 11•2 ng/mL [3•1]; p=0•0014). VWF antigen concentrations were also elevated above the normal range in 16 (80%) of 20 non-ICU patients. We found mortality to be significantly correlated with VWF antigen (r=0•38; p=0•0022) and soluble thrombomodulin (r=0•38; p=0•0078) among all patients. In all patients, soluble thrombomodulin concentrations greater than 3•26 ng/mL were associated with lower rates of hospital discharge (22 [88%] of 25 patients with low concentrations vs 13 [52%] of 25 patients with high concentrations; p=0•0050) and lower likelihood of survival on Kaplan-Meier analysis (hazard ratio 5•9, 95% CI 1•9-18•4; p=0•0087).Interpretation Our findings show that endotheliopathy is present in COVID-19 and is likely to be associated with critical illness and death. Early identification of endotheliopathy and strategies to mitigate its progression might improve outcomes in COVID-19.

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Cytosolic HSP90 requires multiple cochaperones in folding client proteins. However, the function of gp96 (HSP90b1, grp94), an HSP90 paralogue in the endoplasmic reticulum (ER), is believed to be independent of cochaperones. Here, we demonstrate that gp96 chaperones multiple Toll-like receptors (TLRs), but not TLR3, in a manner that is dependent on another ER luminal protein, CNPY3. gp96 directly interacts with CNPY3, and the complex dissociates in the presence of adenosine triphosphate (ATP). Genetic disruption of gp96–CNPY3 interaction completely abolishes their TLR chaperone function. Moreover, we demonstrate that TLR9 forms a multimolecular complex with gp96 and CNPY3, and the binding of TLR9 to either molecule requires the presence of the other. We suggest that CNPY3 interacts with the ATP-sensitive conformation of gp96 to promote substrate loading. Our study has thus established CNPY3 as a TLR-specific cochaperone for gp96.

The recent literature contains reports of thrombotic episodes occurring in patients with human immunodeficiency virus (HIV) infection and various abnormalities predisposing to a hypercoagulable state have also been reported in such patients. To study the incidence of thrombosis in patients infected with HIV, and to assess the correlation of thrombosis with the degree of immunosuppression as well as the association with active illnesses and neoplasms, we reviewed the charts of 131 patients, which include all the patients with the diagnosis of HIV admitted or seen in the clinic between January 1, 1993, and January 1, 1998. The diagnosis of thrombosis was based on documented reports of venous plethysmography or venography for deep venous thrombosis and ventilation-perfusion scan or pulmonary angiography for pulmonary embolus. Risk factors for thrombotic disease were evaluated including general risk factors such as family history, ambulatory status, medications, and data were also collected regarding CD4 cell counts and the presence of concurrent or remote opportunistic infections, acquired immune deficiency syndrome (AIDS)-related malignancy or other AIDS-related diseases at the time of diagnosis of the thrombotic event. We also reviewed the medical literature via MEDLINE and found 45 cases of patients with HIV who developed thromboembolic complications. We found thrombotic complications in 9 of 37 patients with a CD4 count less than 200 cells/mm3 and in 1 of the remaining 94 patients with a CD4 count more than 200 cells/mm3. The difference was significant, with p = 0.00004, and the estimated odds of an event given CD4 cell counts less than 200/mm3 is 29.89 (95% confidence interval). Three patients had abnormalities of anticoagulation proteins. There was a history of opportunistic infections in 5 patients and malignancy in 3 patients. Two patients with autoimmune hemolytic anemia (AIHA) secondary to HIV-infection developed PE upon transfusion of packed red blood cells. The results of this study suggests that AIDS appears to predispose to thrombosis. It also revealed a significant correlation between thrombotic disease and CD4 counts (<200/mm3) as well as the presence of opportunistic infections, AIDS-related neoplasms, or autoimmune disorders associated with HIV such as AIHA. Therefore, clinicians caring for these patients should be aware of thromboembolic disease as a possible complication of AIDS. Further studies to elucidate the mechanisms underlying this abnormal hemostatic profile, the epidemiology, and to answer several questions such as should patients with risk factors for HIV infection who develop thromboembolic complications be further evaluated including tests for HIV are warranted.