Central Nervous System thrombotic microangiopathy in COVID-19 patients: an intriguing hypothesis? (preprint)

Objectives: Neurological manifestations of COVID-19 disease are being increasingly recognized. A growing number of studies has been showing CNS abnormalities on brain imaging.Purpose is to describe brain imaging findings of a population of COVID-19 patients with neurological manifestations and peculiar abnormalities on susceptibility weighted imaging (SWI) sequences.Methods: we retrospectively evaluated imaging data from 50 patients affected by SARS-CoV-2 infection, who underwent a brain MRI because of neurological symptoms between March and June 2020.We focused on those presenting with abnormalities on brain MRI on SWI (positive MRI, P-MRI). We also carried out comparative investigations using patients without SWI abnormalities (negative MRI, N-MRI) as a control group. Non-parametric tests were used. A p-value < 0.05 was considered significant.Results: From 50 patients presenting with neurological symptoms, 10 patients showed brain abnormalities on SWI (P-MRI). Mean age in P-MRI group was 63±12 years; 7 were men. Six patients were admitted to Intensive Care Units (ICUs) and needed invasive ventilation support. P-MRI subjects showed lymphopenia and significantly higher levels of inflammatory markers such as CRP, IL-6, and fibrinogen. No significant differences were found in the coagulation profile. MRI showed diffuse SWI hypointense lesions mostly in occipital and temporal lobes, predominantly located at the grey-white matter junction. Genu and splenium of corpus callosum were involved in 8 of 10 patients. No restricted diffusion or enhancement was associated to SWI lesions.Conclusions: SWI abnormalities in patients with COVID-19 with neurological symptoms may reflect microvascular endothelial damage in the setting of a pro-inflammatory state.

Macropahge expression and prognostic significance of the long pentraxin PTX3 in COVID-19 (preprint)

PTX3 is an essential component of humoral innate immunity, involved in resistance to selected pathogens and in the regulation of inflammation. PTX3 plasma levels are associated with poor outcome in systemic inflammatory conditions and vascular pathology. The present study was designed to assess expression and significance of PTX3 in COVID-19. By bioinformatics analysis of public databases PTX3 expression was detected in lung respiratory cell lines exposed to SARS-CoV-2. By analysis at single cell level of COVID-19 circulating mononuclear cells, we found that PTX3 was selectively expressed by monocytes among circulating leukocytes. Moreover, in lung bronchoalveolar lavage fluid, single cell analysis revealed selective expression of PTX3 in neutrophils and macrophages, which play a major role in the pathogenesis of the disease. By immunohistochemistry, PTX3 was expressed by lung myelomocytic cells, type 2 pneumocytes and vascular endothelial cells. PTX3 plasma levels were determined by ELISA in 96 consecutive patients with a laboratory-confirmed diagnosis of COVID-19. Higher PTX3 plasma levels were observed in 52 (54.2%) patients admitted in ICU (median 21.0ng/mL, IQT 15.5-46.3 vs 12.4ng/mL IQT 6.1-20.2 in ward patients; p=0.0017) and in 22 (23%) patients died by 28 days (39.8ng/mL, IQT 20.2-75.7 vs 15.7ng/mL, IQT 8.2-21.6 in survivors; p=0.0001). After determining an optimal PTX3 cut-off for the primary outcome, the Kaplan-Meier curve showed an increased mortality in patients with PTX3>22.25ng/mL (Log-rank tests p<0.0001). In Cox regression model, PTX3>22.25ng/mL showed an adjusted Hazard Ratio (aHR) of 7.6 (95%CI2.45-23.76) in predicting mortality. Performing a multivariate logistic regression including all inflammatory markers (PTX3, ferritin, D-Dimer, IL-6, and CRP), PTX3 was the only marker significantly associated with death (aHR 1.13;95%CI1.02-1.24; p=0.021). The results reported here suggest that circulating and lung myelomonocytic cells are a major source of PTX3 and that PTX3 plasma levels can serve as a strong prognostic indicator of short-term mortality in COVID-19.

Pulmonary Post-Mortem Findings in a Large Series of COVID-19 Cases from Northern Italy (preprint)

Importance: The analysis of lung tissues of patients with COVID-19 may help understand pathogenesis and clinical outcomes in this life-threatening respiratory illness.Objective: To determine the histological patterns in lung tissue of patients with severe COVID-19.Design and Participants: Lungs tissues of 38 cases who died for COVID-19 in two hospital of Northern Italy were systematically analysed. Hematoxylin-eosin staining, immunohistochemistry for the inflammatory infiltrate and cellular components, electron microscopy were performed.Results: The features of the exudative and proliferative phases of Diffuse Alveolar Disease (DAD) were found: capillary congestion, necrosis of pneumocytes, hyaline membrane, interstitial oedema, pneumocyte hyperplasia and reactive atypia, platelet-fibrin thrombi. The inflammatory infiltrate was composed by macrophages in alveolar lumens and lymphocytes mainly in the interstitium. Electron microscopy revealed viral particles within cytoplasmic vacuoles of pneumocytes.Conclusions and Relevance: The predominant pattern of lung lesions in COVID-19 patients is DAD, as described for the other two coronavirus that infect humans, SARS-CoV and MERS-CoV. Hyaline membrane formation and pneumocyte atypical hyperplasia are frequently found. The main relevant finding is the presence of platelet-fibrin thrombi in small arterial vessels; this important observation fits into the clinical context of coagulopathy which dominates in these patients and which is one of the main targets of therapy.Funding Statement: No FundingDeclaration of Interests: No Conflict of InterestEthics Approval Statement: Tissue samples were taken as part of routine autopsies

THE PATHOGENESIS OF THROMBOEMBOLIC DISEASE IN COVID-19 PATIENTS: COULD BE A CATASTROPHIC ANTIPHOSPHOLIPID SYNDROME? (preprint)

Background The most severely COVID-19 patients need intensive care and show increased risk of thromboembolic events. Although some patients meet the diagnostic criteria for the Disseminated Intravascular Coagulation, the pathogenesis of the diffuse thrombotic status remains unclear. The aim of the present study is to evaluate the presence of antiphospholipid antibodies (aPL) in sera of deceased patients with autoptic proven thrombotic microangiopathy to evaluate if some patients may have developed Catastrophic Antiphospholipid Syndrome (CAPS). Methods Thirty-five patients were enrolled. The available medical history, comorbidities, therapies, laboratory and autopsy findings were collected post-mortem from clinical records. IgA, IgG and IgM anti cardiolipin (ACA) and anti {beta}2 glycoprotein 1 ({beta}2GP1) antibodies, IgG and IgM anti phosphatidylserine/prothrombin (PS/PT) antibodies were tested for all the patients. Results 3/35 (8.6%) patients were slightly positive for aPL: one for ACA IgG and two for ACA IgM but values were low (< 3X the cut off). No patients tested positive for ACA IgA neither for {beta}2GP1 isotypes. 3/35 (8.6%) patients were positive for PS/PT, one for IgG and two for IgM, but values were less than 2X the cut off. No patients showed simultaneous positivity for ACA and PS/ PT. Conclusions It is difficult to categorize the vascular events into a conventional disease: we did not find significant association with anti-phospholipid antibodies. It is most likely that several factors contribute to trigger the hypercoagulability status and the thromboembolism but, on the basis our results, CAPS is probably not involved into the pathogenesis of these phenomena.

Liver and COVID 19 Infection: A Very Preliminary Lesson Learnt from Histological Post-mortem Findings in 48 patients (preprint)

COVID-19 breakout in Italy has caused a huge number of severely ill patients with a serious increase in mortality. Although lungs seem to be the main target of the infection very few information are available about liver involvement in COVID-19 infection, that could possibly evocate a systemic disease targeting a lot of organs. Since now there are no reports of large series of histological evaluation of liver morphology in this setting. Knowledge of histological liver findings connected to clinical data is crucial in management of this disease.Post-mortem wedge liver biopsies from 48 patients died for COVID-19 infection were available from two main hospitals located in northern Italy, Lombardy; all sample were obtained during autopsies. No patient has a significant clinical complain of liver disease or signs of liver failure before and during hospitalization; for each of them laboratory data focused on liver were available. All liver samples showed minimal inflammation features; on the other side, many histological pictures compatible with vascular alterations were observed, characterized by portal vein braches number increase associated with lumen massive dilatation, partial or complete recent luminal thrombosis of portal and sinusoidal vessels, fibrosis of portal tract, focally severely enlarged and fibrotic. Our preliminary results concerning histological liver involvement in COVID-19 infection confirm the clinical impression that liver failure is not a main concern and this organ is not the target of significant inflammatory damage; histopatological findings are highly suggestive for marked alteration of intrahepatic blood vessel network secondary to systemic alterations induced by virus that could target, besides lung parenchyma, cardiovascular system, coagulation cascade or endothelial layer of blood vessels.

Pulmonary post-mortem findings in a large series of COVID-19 cases from Northern Italy (preprint)

Importance. The analysis of lung tissues of patients with COVID-19 may help understand pathogenesis and clinical outcomes in this life-threatening respiratory illness. Objective. To determine the histological patterns in lung tissue of patients with severe COVID-19. Design and participants. Lungs tissues of 38 cases who died for COVID-19 in two hospital of Northern Italy were systematically analysed. Hematoxylin-eosin staining, immunohistochemistry for the inflammatory infiltrate and cellular components, electron microscopy were performed. Results. The features of the exudative and proliferative phases of Diffuse Alveolar Disease (DAD) were found: capillary congestion, necrosis of pneumocytes, hyaline membrane, interstitial oedema, pneumocyte hyperplasia and reactive atypia, platelet-fibrin thrombi. The inflammatory infiltrate was composed by macrophages in alveolar lumens and lymphocytes mainly in the interstitium. Electron microscopy revealed viral particles within cytoplasmic vacuoles of pneumocytes. Conclusions and relevance. The predominant pattern of lung lesions in COVID-19 patients is DAD, as described for the other two coronavirus that infect humans, SARS-CoV and MERS-CoV. Hyaline membrane formation and pneumocyte atypical hyperplasia are frequently found. The main relevant finding is the presence of platelet-fibrin thrombi in small arterial vessels; this important observation fits into the clinical context of coagulopathy which dominates in these patients and which is one of the main targets of therapy.