COVID-19: detection methods in post-mortem samples.

COVID-19 identification is routinely performed on fresh samples, such as nasopharyngeal and oropharyngeal swabs, even if, the detection of the virus in formalin-fixed paraffin-embedded (FFPE) autopsy tissues could help to underlie mechanisms of the pathogenesis that are not well understood.The gold standard for COVID-19 detection in FFPE samples remains the qRT-PCR as in swab samples, contextually other methods have been developed, including immunohistochemistry (IHC), and in situ hybridization (ISH). In this manuscript, we summarize the main data regarding the methods of COVID-19 detection in pulmonary and extra-pulmonary post-mortem samples, and especially the sensitivity and specificity of these assays will be discussed.

COVID-19 induces more pronounced extracellular matrix deposition than other causes of ARDS.

BACKGROUND: Lung fibrosis is a major concern in severe COVID-19 patients undergoing mechanical ventilation (MV). Lung fibrosis frequency in post-COVID syndrome is highly variable and even if the risk is proportionally small, many patients could be affected. However, there is still no data on lung extracellular matrix (ECM) composition in severe COVID-19 and whether it is different from other aetiologies of ARDS. METHODS: We have quantified different ECM elements and TGF-ß expression in lung tissue of 28 fatal COVID-19 cases and compared to 27 patients that died of other causes of ARDS, divided according to MV duration (up to six days or seven days or more). In COVID-19 cases, ECM elements were correlated with lung transcriptomics and cytokines profile. RESULTS: We observed that COVID-19 cases presented significant increased deposition of collagen, fibronectin, versican, and TGF-ß, and decreased decorin density when compared to non-COVID-19 cases of similar MV duration. TGF-ß was precociously increased in COVID-19 patients with MV duration up to six days. Lung collagen was higher in women with COVID-19, with a transition of upregulated genes related to fibrillogenesis to collagen production and ECM disassembly along the MV course. CONCLUSIONS: Fatal COVID-19 is associated with an early TGF-ß expression lung environment after the MV onset, followed by a disordered ECM assembly. This uncontrolled process resulted in a prominent collagen deposition when compared to other causes of ARDS. Our data provides pathological substrates to better understand the high prevalence of pulmonary abnormalities in patients surviving COVID-19.

Intranasal Liposomal Formulation of Spike Protein Adjuvanted with CpG Protects and Boosts Heterologous Immunity of hACE2 Transgenic Mice to SARS-CoV-2 Infection.

Mucosal vaccination appears to be suitable to protect against SARS-CoV-2 infection. In this study, we tested an intranasal mucosal vaccine candidate for COVID-19 that consisted of a cationic liposome containing a trimeric SARS-CoV-2 spike protein and CpG-ODNs, a Toll-like receptor 9 agonist, as an adjuvant. In vitro and in vivo experiments indicated the absence of toxicity following the intranasal administration of this vaccine formulation. First, we found that subcutaneous or intranasal vaccination protected hACE-2 transgenic mice from infection with the wild-type (Wuhan) SARS-CoV-2 strain, as shown by weight loss and mortality indicators. However, when compared with subcutaneous administration, the intranasal route was more effective in the pulmonary clearance of the virus and induced higher neutralizing antibodies and anti-S IgA titers. In addition, the intranasal vaccination afforded protection against gamma, delta, and omicron virus variants of concern. Furthermore, the intranasal vaccine formulation was superior to intramuscular vaccination with a recombinant, replication-deficient chimpanzee adenovirus vector encoding the SARS-CoV-2 spike glycoprotein (Oxford/AstraZeneca) in terms of virus lung clearance and production of neutralizing antibodies in serum and bronchial alveolar lavage (BAL). Finally, the intranasal liposomal formulation boosted heterologous immunity induced by previous intramuscular vaccination with the Oxford/AstraZeneca vaccine, which was more robust than homologous immunity.

Ultrastructural characterization of alveolar microvascular damage in severe COVID-19 respiratory failure.

Endothelial dysfunction is a key phenomenon in COVID-19, induced by direct viral endothelial infection and secondary inflammation, mainly affecting the microvascular circulation. However, few studies described the subcellular aspects of the lung microvasculature and the associated thrombotic phenomena, which are widely present in severe COVID-19 cases. To that end, in this transversal observational study we performed transmission and scanning electron microscopy in nine lung samples of patients who died due to COVID-19, obtained via minimally invasive autopsies in Sao Paulo, Brazil, in 2020. All patients died due to acute respiratory failure and had microvascular thrombosis at histology. Electron microscopy revealed areas of endothelial damage with basal lamina disruption and virus infection in endothelial cells. In the capillary lumens, the ultrastructure of the thrombi is depicted, with red blood cells stacking, dysmorphism and hemolysis, fibrin meshworks, and extracellular traps. Our description illustrates the complex pathophysiology of microvascular thrombosis at the cellular level, which leads to some of the peculiar characteristics of severe COVID-19.NEW & NOTEWORTHY In this study, electron microscopy was used to explain the pathophysiology of respiratory failure in severe COVID-19. Before the advent of vaccination, as the virus entered the respiratory system, it rapidly progressed to the alveolar capillary network and, before causing exudative alveolar edema, it caused mainly thrombosis of the pulmonary microcirculation with preserved lung compliance explaining "happy hypoxia." Timing of anticoagulation is of pivotal importance in this disease.

Understanding yellow fever-associated myocardial injury: an autopsy study.

BACKGROUND: Yellow fever (YF) is a viral hemorrhagic fever, endemic in parts of South America and Africa. There is scarce evidence about the pathogenesis of the myocardial injury. The objective of this study is to evaluate the cardiac pathology in fatal cases of YF. METHODS: This retrospective autopsy study included cases from the São Paulo (Brazil) epidemic of 2017-2019. We reviewed medical records and performed cardiac tissue histopathological evaluation, electron microscopy, immunohistochemical assays, RT-qPCR for YF virus (YFV)-RNA, and proteomics analysis on inflammatory and endothelial biomarkers. FINDINGS: Seventy-three confirmed YF cases with a median age of 48 (34-60) years were included. We observed myocardial fibrosis in 68 (93.2%) patients; cardiomyocyte hypertrophy in 68 (93.2%); endothelial alterations in 67 (91.8%); fiber necrosis in 50 (68.5%); viral myocarditis in 9 (12.3%); and secondary myocarditis in 5 (6.8%). Four out of five patients with 17DD vaccine-associated viscerotropic disease presented with myocarditis. The cardiac conduction system showed edema, hemorrhages and endothelial fibrinoid necrosis. Immunohistochemistry detected CD68-positive inflammatory interstitial cells and YFV antigens in endothelial and inflammatory cells. YFV-RNA was detected positive in 95.7% of the cardiac samples. The proteomics analysis demonstrated that YF patients had higher levels of multiple inflammatory and endothelial biomarkers in comparison to cardiovascular controls, and higher levels of interferon gamma-induced protein 10 (IP-10) in comparison to sepsis (p = 0.01) and cardiovascular controls (p < 0.001) in Dunn test. INTERPRETATION: Myocardial injury is frequent in severe YF, due to multifactorial mechanisms, including direct YFV-mediated damage, endothelial cell injury, and inflammatory response, with a possible prominent role for IP-10. FUNDING: This study was funded by Fundação de Amparo à Pesquisa do Estado de São Paulo, Bill and Melinda Gates Foundation, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.

Transcriptome analysis of six tissues obtained post-mortem from sepsis patients.

Septic shock is a life-threatening clinical condition characterized by a robust immune inflammatory response to disseminated infection. Little is known about its impact on the transcriptome of distinct human tissues. To address this, we performed RNA sequencing of samples from the prefrontal cortex, hippocampus, heart, lung, kidney and colon of seven individuals who succumbed to sepsis and seven uninfected controls. We identified that the lungs and colon were the most affected organs. While gene activation dominated, strong inhibitory signals were also detected, particularly in the lungs. We found that septic shock is an extremely heterogeneous disease, not only when different individuals are investigated, but also when comparing different tissues of the same patient. However, several pathways, such as respiratory electron transport and other metabolic functions, revealed distinctive alterations, providing evidence that tissue specificity is a hallmark of sepsis. Strikingly, we found evident signals of accelerated ageing in our sepsis population.

What else in times of COVID-19? The role of minimally invasive autopsy for the differential diagnosis of acute respiratory failure in a case of kala-azar.

Visceral leishmaniasis (VL) is a chronic vector-borne zoonotic disease caused by trypanosomatids, considered endemic in 98 countries, mainly associated with poverty. About 50,000-90,000 cases of VL occur annually worldwide, and Brazil has the second largest number of cases in the world. The clinical picture of VL is fever, hepatosplenomegaly, and pancytopenia, progressing to death in 90% of cases due to secondary infections and multi-organ failure, if left untreated. We describe the case of a 25-year-old female who lived in the metropolitan area of Sao Paulo, who had recently taken touristic trips to several rural areas in Southeastern Brazil and was diagnosed post-mortem. During the hospitalization in a hospital reference for the treatment of COVID-19, the patient developed acute respiratory failure, with chest radiographic changes, and died due to refractory shock. The ultrasound-guided minimally invasive autopsy diagnosed VL (macrophages containing amastigote forms of Leishmania in the spleen, liver and bone marrow), as well as pneumonia and bloodstream infection by gram-negative bacilli.

Obesity Induces an Impaired Placental Antiviral Immune Response in Pregnant Women Infected with Zika Virus.

Obesity is increasing in incidence worldwide, especially in women, which can affect the outcome of pregnancy. During this period, viral infections represent a risk to the mother, the placental unit, and the fetus. The Zika virus (ZIKV) outbreak in Brazil has been the cause of congenital Zika syndrome (CZS), with devastating consequences such as microcephaly in newborns. Herein, we analyzed the impact of maternal overweight/obesity on the antiviral factors' expression in the placental tissue of Zika-infected mothers. We accessed placentas from women with and without obesity from 34 public health units (São Paulo) and from Zika-infected mothers with and without obesity from the Clinical Cohort Study of ZIKV pregnant women (Rio de Janeiro, Brazil). We first verified that obesity, without infection, did not alter the constitutive transcriptional expression of antiviral factors or IFN type I/III expression. Interestingly, obesity, when associated with ZIKV infection, showed a decreased transcriptional expression of RIG-I and IFIH1 (MDA-5 protein precursor gene). At the protein level, we also verified a decreased RIG-I and IRF-3 expression in the decidual placenta from the Zika-infected obese group, regardless of microcephaly. This finding shows, for the first time, that obesity associated with ZIKV infection leads to an impaired type I IFN downstream signaling pathway in the maternal-fetal interface.

Yellow Fever Vaccine-Associated Viscerotropic Disease among Siblings, São Paulo State, Brazil.

We describe 5 cases of yellow fever vaccine-associated viscerotropic disease (YEL-AVD) in 2 familial clusters during the 2017-2018 yellow fever (YF) vaccination campaign in São Paulo state, Brazil. The first case was that of a 40-year-old white man who died of icterohemorrhagic syndrome, which was confirmed to be YEL-AVD by using real-time reverse transcription PCR to detect 17DD YF vaccine in the liver. Ten years previously, his brother died of a clinically similar disease without a confirmed diagnosis 9 days after YF vaccination. The second cluster included 3 of 9 siblings in whom hepatitis developed in the first week after receiving fractionated doses of YF vaccine. Two of them died of hemorrhagic diathesis and renal and respiratory failure, and 17DD-YF vaccine was detected in serum samples from all patients and in the liver in 1 case. Genetic factors might play a substantial role in the incidence of YEL-AVD.

What else in times of COVID-19? The role of minimally invasive autopsy for the differential diagnosis of acute respiratory failure in a case of kala-azar

ABSTRACT Visceral leishmaniasis (VL) is a chronic vector-borne zoonotic disease caused by trypanosomatids, considered endemic in 98 countries, mainly associated with poverty. About 50,000-90,000 cases of VL occur annually worldwide, and Brazil has the second largest number of cases in the world. The clinical picture of VL is fever, hepatosplenomegaly, and pancytopenia, progressing to death in 90% of cases due to secondary infections and multi-organ failure, if left untreated. We describe the case of a 25-year-old female who lived in the metropolitan area of Sao Paulo, who had recently taken touristic trips to several rural areas in Southeastern Brazil and was diagnosed post-mortem. During the hospitalization in a hospital reference for the treatment of COVID-19, the patient developed acute respiratory failure, with chest radiographic changes, and died due to refractory shock. The ultrasound-guided minimally invasive autopsy diagnosed VL (macrophages containing amastigote forms of Leishmania in the spleen, liver and bone marrow), as well as pneumonia and bloodstream infection by gram-negative bacilli.

Chronic exposure to cigarette smoke transiently worsens the disease course in a mouse model of pulmonary paracoccidioidomycosis.

Paracoccidioidomycosis (PCM) may present as an acute/subacute clinical form, characterized by a progressive disease arising from the airborne initial infection, or, most often, as an asymptomatic or subclinical infection that may manifest later during an individual's life, the chronic form. Epidemiological studies show the existence of a strong association between smoking and the development of the chronic form. Current evidence demonstrates that cigarette smoke (CS) has immunosuppressive properties that could be implicated in the increasing susceptibility to the chronic form of PCM. To address this issue, we developed a murine model of a non-progressive pulmonary form of PCM that was exposed to CS at a magnitude that mimicked a moderate smoker. The chronic CS exposure started after 2 weeks and lasted up until 20 weeks post-infection, with the aim of mimicking human natural history, since it is estimated that individuals from endemic areas are infected early in life. The control group consisted of infected but not CS-exposed mice. We assessed the lung fungal burden (colony forming units [CFU]) and the area affected by the granulomatous inflammatory response, fungal dissemination to spleen and liver, and, by immunohistochemistry, the presence of CD4 and CD8 lymphocytes, CD68 and MAC-2 macrophages, and IFN-γ, IL-10 and TNF expressing cells within the granulomatous response. We detected a CS effect as early as 2 weeks after exposure (four weeks post-infection) when the lung CFU of exposed animals was significantly higher than in their non-exposed counterparts. At 12 weeks, the CS-exposed animals presented a more severe disease, as witnessed by the persistent higher lung fungal load (although it did not reach statistical significance [ p = 0.054]), greater dissemination to other organs, greater affected area of the lung, decreased IFN-γ/IL-10 ratio, and higher TNF expression within the granulomas, compared with CS-non-exposed mice. The number of CD4 and CD8 lymphocytes infiltrating the granulomas was similar between both mice groups, but there was a decrease in the number of MAC-2+ macrophages. No difference was noted in the CD68+ macrophage number. However, the follow-up in week 20 showed that the immunological effects of exposure to CS ceased, with both CS and NCS mice showing the same infectious features, i.e., a trend for resolution of the infection. In conclusion, we show that chronic CS-exposure alters the course of the disease in an experimental model of subclinical pulmonary PCM, confirming the epidemiological link between CS-exposure and the chronic form of PCM. However, we also show that this effect is transitory, being detected between 4- and 12-weeks post-infection but not thereafter. The possible immune mechanisms that mediate this effect and the reasons for its transitory effect are discussed.

Terlipressin combined with conservative fluid management attenuates hemorrhagic shock-induced acute kidney injury in rats.

Hemorrhagic shock (HS), a major cause of trauma-related mortality, is mainly treated by crystalloid fluid administration, typically with lactated Ringer's (LR). Despite beneficial hemodynamic effects, such as the restoration of mean arterial pressure (MAP), LR administration has major side effects, including organ damage due to edema. One strategy to avoid such effects is pre-hospitalization intravenous administration of the potent vasoconstrictor terlipressin, which can restore hemodynamic stability/homeostasis and has anti-inflammatory effects. Wistar rats were subjected to HS for 60 min, at a target MAP of 30-40 mmHg, thereafter being allocated to receive LR infusion at 3 times the volume of the blood withdrawn (liberal fluid management); at 2 times the volume (conservative fluid management), plus terlipressin (10 µg/100 g body weight); and at an equal volume (conservative fluid management), plus terlipressin (10 µg/100 g body weight). A control group comprised rats not subjected to HS and receiving no fluid resuscitation or treatment. At 15 min after fluid resuscitation/treatment, the blood previously withdrawn was reinfused. At 24 h after HS, MAP was higher among the terlipressin-treated animals. Terlipressin also improved post-HS survival and provided significant improvements in glomerular/tubular function (creatinine clearance), neutrophil gelatinase-associated lipocalin expression, fractional excretion of sodium, aquaporin 2 expression, tubular injury, macrophage infiltration, interleukin 6 levels, interleukin 18 levels, and nuclear factor kappa B expression. In terlipressin-treated animals, there was also significantly higher angiotensin II type 1 receptor expression and normalization of arginine vasopressin 1a receptor expression. Terlipressin associated with conservative fluid management could be a viable therapy for HS-induced acute kidney injury, likely attenuating such injury by modulating the inflammatory response via the arginine vasopressin 1a receptor.

Phylogeographic patterns of the yellow fever virus around the metropolitan region of São Paulo, Brazil, 2016-2019.

From 2016 to 2019, the largest outbreak caused by the Yellow Fever virus (YFV) in the 21st century in the Americas occurred in southeastern Brazil. A sylvatic cycle of transmission was reported near densely populated areas, such as the large metropolitan area of the city of São Paulo. Here, we describe the origin, spread, and movement of the YFV throughout the state of São Paulo. Whole-genome sequences were obtained from tissues of two patients who died due to severe yellow fever, during 2018-2019. Molecular analysis indicated that all analyzed tissues were positive for YFV RNA, with the liver being the organ with the highest amount of viral RNA. Sequence analysis indicates that genomes belonged to the South American genotype I and were grouped in the epidemic clade II, which includes sequences from the states of Goiás, Minas Gerais, and São Paulo of previous years. The analysis of viral dispersion indicates that the outbreak originated in Goiás at the end of 2014 and reached the state of São Paulo through the state of Minas Gerais after 2016. When the virus reached near the urban area, it spread towards both the east and south regions of the state, not establishing an urban transmission cycle in the metropolitan region of São Paulo. The virus that moved towards the east met with YFV coming from the south of the state of Rio de Janeiro, and the YFV that was carried to the south reached the Brazilian states located in the south region of the country.

Diffuse alveolar damage patterns reflect the immunological and molecular heterogeneity in fatal COVID-19.

BACKGROUND: Severe COVID-19 lung disease exhibits a high degree of spatial and temporal heterogeneity, with different histological features coexisting within a single individual. It is important to capture the disease complexity to support patient management and treatment strategies. We provide spatially decoded analyses on the immunopathology of diffuse alveolar damage (DAD) patterns and factors that modulate immune and structural changes in fatal COVID-19. METHODS: We spatially quantified the immune and structural cells in exudative, intermediate, and advanced DAD through multiplex immunohistochemistry in autopsy lung tissue of 18 COVID-19 patients. Cytokine profiling, viral, bacteria, and fungi detection, and transcriptome analyses were performed. FINDINGS: Spatial DAD progression was associated with expansion of immune cells, macrophages, CD8+ T cells, fibroblasts, and (lymph)angiogenesis. Viral load correlated positively with exudative DAD and negatively with disease/hospital length. In all cases, enteric bacteria were isolated, and Candida parapsilosis in eight cases. Cytokines correlated mainly with macrophages and CD8+T cells. Pro-coagulation and acute repair were enriched pathways in exudative DAD whereas intermediate/advanced DAD had a molecular profile of elevated humoral and innate immune responses and extracellular matrix production. INTERPRETATION: Unraveling the spatial and molecular immunopathology of COVID-19 cases exposes the responses to SARS-CoV-2-induced exudative DAD and subsequent immune-modulatory and remodeling changes in proliferative/advanced DAD that occur side-by-side together with secondary infections in the lungs. These complex features have important implications for disease management and the development of novel treatments. FUNDING: CNPq, Bill and Melinda Gates Foundation, HC-Convida, FAPESP, Regeneron Pharmaceuticals, and the Swedish Heart & Lung Foundation.

Understanding Sabiá virus infections (Brazilian mammarenavirus).

BACKGROUND: Only two naturally occurring human Sabiá virus (SABV) infections have been reported, and those occurred over 20 years ago. METHODS: We diagnosed two new cases of SABV infection using metagenomics in patients thought to have severe yellow fever and described new features of histopathological findings. RESULTS: We characterized clinical manifestations, histopathology and analyzed possible nosocomial transmission. Patients presented with hepatitis, bleeding, neurological alterations and died. We traced twenty-nine hospital contacts and evaluated them clinically and by RT-PCR and neutralizing antibodies. Autopsies uncovered unique features on electron microscopy, such as hepatocyte "pinewood knot" lesions. Although previous reports with similar New-World arenavirus had nosocomial transmission, our data did not find any case in contact tracing. CONCLUSIONS: Although an apparent by rare, Brazilian mammarenavirus infection is an etiology for acute hemorrhagic fever syndrome. The two fatal cases had peculiar histopathological findings not previously described. The virological diagnosis was possible only by contemporary techniques such as metagenomic assays. We found no subsequent infections when we used serological and molecular tests to evaluate close contacts.

COVID-19-Associated cardiac pathology at the postmortem evaluation: a collaborative systematic review.

BACKGROUND: Many postmortem studies address the cardiovascular effects of COVID-19 and provide valuable information, but are limited by their small sample size. OBJECTIVES: The aim of this systematic review is to better understand the various aspects of the cardiovascular complications of COVID-19 by pooling data from a large number of autopsy studies. DATA SOURCES: We searched the online databases Ovid EBM Reviews, Ovid Embase, Ovid Medline, Scopus, and Web of Science for concepts of autopsy or histopathology combined with COVID-19, published between database inception and February 2021. We also searched for unpublished manuscripts using the medRxiv services operated by Cold Spring Harbor Laboratory. STUDY ELIGIBILITY CRITERIA: Articles were considered eligible for inclusion if they reported human postmortem cardiovascular findings among individuals with a confirmed SARS coronavirus type 2 (CoV-2) infection. PARTICIPANTS: Confirmed COVID-19 patients with post-mortem cardiovascular findings. INTERVENTIONS: None. METHODS: Studies were individually assessed for risk of selection, detection, and reporting biases. The median prevalence of different autopsy findings with associated interquartile ranges (IQRs). RESULTS: This review cohort contained 50 studies including 548 hearts. The median age of the deceased was 69 years. The most prevalent acute cardiovascular findings were myocardial necrosis (median: 100.0%; IQR, 20%-100%; number of studies = 9; number of patients = 64) and myocardial oedema (median: 55.5%; IQR, 19.5%-92.5%; number of studies = 4; number of patients = 46). The median reported prevalence of extensive, focal active, and multifocal myocarditis were all 0.0%. The most prevalent chronic changes were myocyte hypertrophy (median: 69.0%; IQR, 46.8%-92.1%) and fibrosis (median: 35.0%; IQR, 35.0%-90.5%). SARS-CoV-2 was detected in the myocardium with median prevalence of 60.8% (IQR 40.4-95.6%). CONCLUSIONS: Our systematic review confirmed the high prevalence of acute and chronic cardiac pathologies in COVID-19 and SARS-CoV-2 cardiac tropism, as well as the low prevalence of myocarditis in COVID-19.

Discrepancies Between Clinical and Autopsy Diagnoses in Rapid Response Team-Assisted Patients: What Are We Missing?

OBJECTIVES: The rapid response team (RRT) assists hospitalized patients with sudden clinical deterioration. There is scarce evidence of diagnostic accuracy in this scenario, but it is possible that a considerable rate of misdiagnosis exists. Autopsy remains a valuable tool for assessing such question. This study aimed to compare clinical (premortem) and autopsy (postmortem) diagnoses in patients assisted by the RRT and describe major discrepancies. METHODS: We reviewed 104 clinical data and autopsies from patients assisted by the RRT during a cardiac arrest event in a tertiary care hospital in Brazil. Clinical and autopsy diagnostic discrepancies were classified using the Goldman criteria. Other clinical and pathological data were described, and the group with major diagnostic discrepancies was further analyzed. RESULTS: We found 39 (37.5%) patients with major diagnostic discrepancies. Most frequent immediate causes of death in this group determined by autopsy were sepsis (36%), pulmonary embolism (23%) and hemorrhagic shock (21%). Pulmonary embolism was the cause of death significantly more frequent in the major discrepancy group than in the minor discrepancy group (23% versus 3%, P = 0.002). We individually described all major diagnostic discrepancies. CONCLUSIONS: We found a high rate (37.5%) of major misdiagnosis in autopsies from patients assisted by the RRT in a tertiary teaching hospital. Pulmonary embolism was the most inaccurate fatal diagnosis detected by autopsy.