ABSTRACT
Background: The pathobiology of in situ pulmonary thrombosis in acute respiratory distress syndrome (ARDS) due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is incompletely characterized. In human pulmonary artery endothelial cells (HPAECs), hypoxia upregulates expression of a pro-thrombotic NEDD9 peptide (N9 ) on the extracellular plasma membrane surface. We hypothesized that increased pulmonary endothelial N9 is a novel feature of the SARS-CoV-2 pathophenotype. Methods: Paraffin-embedded autopsy lung specimens were acquired from patients with ARDS due to SARS-CoV-2 infection (n=13), ARDS of other causes (n=10), and non-disease controls (n=5). Immunofluorescence characterized expression of N9 , fibrin, and TCF12, a putative binding target of SARS-CoV-2 and known transcriptional regulator of NEDD9. We performed RNA-Seq on mRNA isolated from control HPAECs treated with normoxia or hypoxia (0.2% O2 ) for 24 hr. Immunoprecipitation-liquid chromatography-mass spectrometry (IP-LC-MS) profiled protein-protein interactions involving N9 relevant to thrombus stabilization. Results: Compared to non-SARS-CoV-2-ARDS lungs, pulmonary endothelial N9 expression and N9-fibrin colocalization was increased by 174% (P<0.002) and 212% (P<0.001) in SARS-CoV-2-ARDS, respectively. Compared to normoxia, hypoxia increased TCF12 mRNA quantity significantly in HPAECs in vitro [+1.19-fold, P=0.001;false discovery rate (FDR)=0.005]. Pulmonary endothelial nuclear TCF12 expression was also increased by 370% in SARS-CoV-2-ARDS vs. controls. In HPAEC plasma membranes, IP-LC-MS identified a novel protein-protein interaction between NEDD9 and the β3 subunit of the αvβ3 integrin, which regulates fibrin anchoring to endothelial cells. Conclusions: Compared to non-SARS-CoV-2-ARDS, SARS-CoV-2-ARDS is associated with increased pulmonary endothelial N9 expression and N9-fibrin colocalization in microthrombi in situ. Increased hypoxia signaling or SARS-CoV-2-mediated regulation of TCF12 are potential mechanisms by which to explain these findings. Identifying N9 in the pulmonary microthrombi of SARS-CoV-2 lungs may have important pathobiological and, potentially, therapeutic implications for ARDS patients.
ABSTRACT
Rationale: Severe SARS Co-V2 (COVID-19) infections are characterized by ARDS, cytokine storm, and multisystem organ failure. Longterm outcomes of these patients requiring long-term acute care (LTAC) have not been clarified. Given the severity of the initial acute illness, poor longterm outcomes are likely. We hypothesized that patients with severe COVID-19 infections would have outcomes worse than non-COVID-19 patients with multisystem organ failure. We tested this by comparing LTAC outcomes in patients having severe COVID-19 disease with patients without COVID-19 who required LTAC after critical illness. Methods: We conducted a chart review of the 275 COVID-19-positive patients requiring intensive care unit (ICU) care discharged from the Brigham and Women's hospital from January 1-July 31, 2020 and compared them to a cohort of 241 ICU patients requiring LTAC who are part of a quality improvement program to enhance care continuity (CC). Statistical analyses used Student-t tests and Chi-square analyses, with P < 0.05 accepted as statistically significant. Results: 65 of 279 COVID-19 patients required LTAC, with 57 patients discharging to the same LTAC used for CC patients. Similar to prior reports, the proportion of Black (28%) and Hispanic (10%) patients were significantly (P < 0.05) greater in COVID-19 patients compared to the CC patients (9% Black and 6% Hispanic). There were no differences between groups in the average patient age: COVID-19 patients (62 ±14.2) and CC patients (60 ±15) or the proportion of males: COVID-19 patients (37, 64%) compared to the CC patients (137, 57%). At transfer to LTAC, 25% CC patients but only 7% COVID-19 patients required mechanical ventilation (MV), although 90% of the COVID-19 patients had required MV during their acute hospitalization. After LTAC transfer, significantly (P < 0.05) fewer COVID-19 patients (12%) compared to CC patients (28%) required readmission to an acute hospital within 30 days of the acute hospital discharge. Additionally, significantly more (P < 0.05) COVID-19 patients (41, 71%) compared to CC patients (73, 30%) were discharged to home after LTAC. Conclusions: The low rates of early readmission and the high rates of home discharge in the COVID patients compared to the CC patients were unexpected and indicate that COVID-19 patients requiring LTAC have outcomes that are comparable, and possibly better than, similar patients without COVID-19. The possible contributing factors for improved outcomes in COVID-19 patients are unknown but may include a lower burden of comorbid disease in these patients and better pre-morbid functional status.