ABSTRACT
COVID-19 is a deadly pulmonary disease with unique clinical features. A thorough understanding of the molecular and histological correlates of the disease is still missing, especially because post-mortem analysis of COVID-19-affected organs has been so far scant and often anecdotical. Here we report the results of the systematic analysis of 41 consecutive post-mortem samples from individuals who died of COVID-19. We found that the disease is characterized by extensive alveolar damage and thrombosis of the lung micro- and macro-vasculature. Thrombi were in different stages of organization, consistent with an ongoing, endogenous thrombotic process. In all the analyzed samples, in situ RNA hybridization showed that pneumocytes and vascular endothelial cells had massive presence of viral RNA even at the later stages of the disease. An additional feature of the disease was the presence, in the vast majority of patients, of a large number of dysmorphic pneumocytes, often forming large syncytial elements, a consequence of the fusogenic activity of the viral Spike protein, detected with specific antibodies. Despite occasional presence of virus-positive cells in the heart, no overt signs of viral infection were detected in other organs, which showed common alterations compatible with prolonged hypoxia, multifocal organ disease or previous comorbidities. In summary, COVID-19 is a unique interstitial pneumonia with extensive lung thrombosis, long-term persistence of viral replication in pneumocytes and endothelial cells, along with the presence of infected cellular syncytia in the lung. We propose that several of the COVID-19 disease features are due to the persistence of virus-infected cells in the lungs of the infected individuals for the duration of the disease.
ABSTRACT
BackgroundIn hospitalized patients with COVID-19 pneumonia, progression to acute respiratory failure requiring invasive mechanical ventilation (MV) is associated with significant morbidity and mortality. Severe dysregulated systemic inflammation is the putative mechanism. We hypothesize that early prolonged methylprednisolone (MP) treatment could accelerate disease resolution, decreasing the need for ICU and mortality. MethodsWe conducted a multicenter, observational study to explore the association between exposure to prolonged, low-dose, MP treatment and need for ICU referral, intubation or death within 28 days (composite primary endpoint) in patients with severe COVID-19 pneumonia admitted to Italian respiratory high-dependency units. Secondary outcomes were invasive MV-free days and changes in C-reactive protein (CRP) levels. ResultsFindings are reported as MP (n=83) vs. control (n=90). The composite primary endpoint was met by 19 vs. 40 [adjusted hazard ratio (HR) 0.41; 95% confidence interval (CI): 0.24-0.72]. Transfer to ICU and need for invasive MV was necessary in 15 vs. 27 (p=0.07) and 14 vs. 26 (p=0.10), respectively. By day 28, the MP group had fewer deaths (6 vs. 21, adjusted HR=0.29; 95% CI: 0.12-0.73) and more days off invasive MV (24.0 {+/-} 9.0 vs. 17.5 {+/-} 12.8; p=0.001). Study treatment was associated with rapid improvement in PaO2:FiO2 and CRP levels. The complication rate was similar for the two groups (p=0.84). ConclusionIn patients with severe COVID-19 pneumonia, early administration of prolonged MP treatment was associated with a significantly lower hazard of death (71%) and decreased ventilator dependence. Randomized controlled studies are needed to confirm these findings. RegistrationClinicalTrials.gov. Identifier: NCT04323592
