SARS-CoV-2 infection causes dopaminergic neuron senescence

COVID-19 patients commonly present with signs of central nervous system and/or peripheral nervous system dysfunction. Here, we show that midbrain dopamine (DA) neurons derived from human pluripotent stem cells (hPSCs) are selectively susceptible and permissive to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. SARS-CoV-2 infection of DA neurons triggers an inflammatory and cellular senescence response. High-throughput screening in hPSC-derived DA neurons identified several FDA-approved drugs that can rescue the cellular senescence phenotype by preventing SARS-CoV-2 infection. We also identified the inflammatory and cellular senescence signature and low levels of SARS-CoV-2 transcripts in human substantia nigra tissue of COVID-19 patients. Furthermore, we observed reduced numbers of neuromelanin+ and tyrosine-hydroxylase (TH)+ DA neurons and fibers in a cohort of severe COVID-19 patients. Our findings demonstrate that hPSC-derived DA neurons are susceptible to SARS-CoV-2, identify candidate neuroprotective drugs for COVID-19 patients, and suggest the need for careful, long-term monitoring of neurological problems in COVID-19 patients.

Targeted viral adaptation generates a simian-tropic hepatitis B virus that infects marmoset cells

Hepatitis B virus (HBV) only infects humans and chimpanzees, posing major challenges for modeling HBV infection and chronic viral hepatitis. The major barrier in establishing HBV infection in non-human primates lies at incompatibilities between HBV and simian orthologues of the HBV receptor, sodium taurocholate co-transporting polypeptide (NTCP). Through mutagenesis analysis and screening among NTCP orthologues from Old World monkeys, New World monkeys and prosimians, we determined key residues responsible for viral binding and internalization, respectively and identified marmosets as a suitable candidate for HBV infection. Primary marmoset hepatocytes and induced pluripotent stem cell-derived hepatocyte-like cells support HBV and more efficient woolly monkey HBV (WMHBV) infection. Adapted chimeric HBV genome harboring residues 1-48 of WMHBV preS1 generated here led to a more efficient infection than wild-type HBV in primary and stem cell derived marmoset hepatocytes. Collectively, our data demonstrate that minimal targeted simianization of HBV can break the species barrier in small NHPs, paving the path for an HBV primate model.

Dual-Reporter System for Real-Time Monitoring of SARS-CoV-2 Main Protease Activity in Live Cells Enables Identification of an Allosteric Inhibition Path

The SARS-CoV-2 pandemic is an ongoing threat to global health, and the continuing emergence of contagious variants highlights the urgent need for additional antiviral therapy to attenuate COVID-19 disease. The SARS-CoV-2 main protease (3CL^pro) presents an attractive target for such therapy due to its high sequence conservation and key role in the viral life cycle. In this study, we designed a fluorescent-luminescent cell-based reporter for the detection and quantification of 3CL^pro intracellular activity. Employing this platform, we examined the efficiency of known protease inhibitors against 3CL^pro and further identified potent inhibitors through high-throughput chemical screening. Computational analysis confirmed a direct interaction of the lead compounds with the protease catalytic site and identified a prototype for efficient allosteric inhibition. These developments address a pressing need for a convenient sensor and specific targets for both virus detection and rapid discovery of potential inhibitors.

SARS-CoV-2 infection in hamsters and humans results in lasting and unique systemic perturbations after recovery

The host response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can result in prolonged pathologies collectively referred to as post-acute sequalae of COVID-19 (PASC) or long COVID. To better understand the mechanism underlying long COVID biology, we compared the short- and long-term systemic responses in the golden hamster after either SARS-CoV-2 or influenza A virus (IAV) infection. Results demonstrated that SARS-CoV-2 exceeded IAV in its capacity to cause permanent injury to the lung and kidney and uniquely affected the olfactory bulb (OB) and olfactory epithelium (OE). Despite a lack of detectable infectious virus, the OB and OE demonstrated myeloid and T cell activation, proinflammatory cytokine production, and an interferon response that correlated with behavioral changes extending a month after viral clearance. These sustained transcriptional changes could also be corroborated from tissue isolated from individuals who recovered from COVID-19. These data highlight a molecular mechanism for persistent COVID-19 symptomology and provide a small animal model to explore future therapeutics.

Sensing of SARS-CoV-2 by pDCs and their subsequent production of IFN-I contribute to macrophage-induced cytokine storm during COVID-19

Lung-infiltrating macrophages create a marked inflammatory milieu in a subset of patients with COVID-19 by producing a cytokine storm, which correlates with increased lethality. However, these macrophages are largely not infected by SARS-CoV-2, so the mechanism underlying their activation in the lung is unclear. Type I interferons (IFN-I) contribute to protecting the host against SARS-CoV-2 but may also have some deleterious effect, and the source of IFN-I in the lungs of infected patients is not well defined. Plasmacytoid dendritic cells (pDCs), a key cell type involved in antiviral responses, can produce IFN-I in response to SARS-CoV-2. We observed the infiltration of pDCs in the lungs of SARS-CoV-2-infected patients, which correlated with strong IFN-I signaling in lung macrophages. In patients with severe COVID-19, lung macrophages expressed a robust inflammatory signature, which correlated with persistent IFN-I signaling at the single-cell level. Hence, we observed the uncoupling in the kinetics of the infiltration of pDCs in the lungs and the associated IFN-I signature, with the cytokine storm in macrophages. We observed that pDCs were the dominant IFN-α-producing cells in response to the virus in the blood, whereas macrophages produced IFN-α only when in physical contact with infected epithelial cells. We also showed that IFN-α produced by pDCs, after the sensing of SARS-CoV-2 by TLR7, mediated changes in macrophages at both transcriptional and epigenetic levels, which favored their hyperactivation by environmental stimuli. Together, these data indicate that the priming of macrophages can result from the response by pDCs to SARS-CoV-2, leading to macrophage activation in patients with severe COVID-19.

Molecular clones of genetically distinct hepatitis B virus genotypes reveal distinct host and drug treatment responses

Background & Aims

HBV exhibits wide genetic diversity with at least 9 genotypes (GTs), which differ in terms of prevalence, geographic distribution, natural history, disease progression, and treatment outcome. However, differences in HBV replicative capacity, gene expression, and infective capability across different GTs remain incompletely understood. Herein, we aimed to study these crucial aspects using newly constructed infectious clones covering the major HBV GTs.

Methods

The replicative capacity of infectious clones covering HBV GTs A-E was analyzed in cell lines, primary hepatocytes and humanized mice. Host responses and histopathology induced by the different HBV GTs were characterized in hydrodynamically injected mice. Differences in treatment responses to entecavir and various HBV capsid inhibitors were also quantified across the different genetically defined GTs.

Results

Patient-derived HBV infectious clones replicated robustly both in vitro and in vivo. GTs A and D induce more pronounced intrahepatic and proinflammatory cytokine responses which correlated with faster viral clearance. Notably, all 5 HBV clones robustly produced viral particles following transfection into HepG2 cells, and these particles were infectious in HepG2-NTCP cells, primary human hepatocytes and human chimeric mice. Notably, GT D virus exhibited higher infectivity than GTs A, B, C and E in vitro, although it was comparable to GT A and B in the human liver chimeric mice in vivo. HBV capsid inhibitors were more readily capable of suppressing HBV GTs A, B, D and E than C.

Conclusions

The infectious clones described here have broad utility as genetic tools that can mechanistically dissect intergenotypic differences in antiviral immunity and pathogenesis and aid in HBV drug development and screening.

Lay summary

The hepatitis B virus (HBV) is a major contributor to human morbidity and mortality. HBV can be categorized into a number of genotypes, based on their specific genetic make-up, of which 9 are well known. We isolated and cloned the genomes of 5 of these genotypes and used them to create valuable tools for future research on this clinically important virus.

Inflammatory responses in the placenta upon SARS-CoV-2 infection late in pregnancy

The effect of SARS-CoV-2 infection on placental function is not well understood. Analysis of placentas from women who tested positive at delivery showed SARS-CoV-2 genomic and subgenomic RNA in 22 out of 52 placentas. Placentas from two mothers with symptomatic COVID-19 whose pregnancies resulted in adverse outcomes for the fetuses contained high levels of viral Alpha variant RNA. The RNA was localized to the trophoblasts that cover the fetal chorionic villi in direct contact with maternal blood. The intervillous spaces and villi were infiltrated with maternal macrophages and T cells. Transcriptome analysis showed an increased expression of chemokines and pathways associated with viral infection and inflammation. Infection of placental cultures with live SARS-CoV-2 and spike protein-pseudotyped lentivirus showed infection of syncytiotrophoblast and, in rare cases, endothelial cells mediated by ACE2 and Neuropilin-1. Viruses with Alpha, Beta, and Delta variant spikes infected the placental cultures at significantly greater levels.

Coagulation factors directly cleave SARS-CoV-2 spike and enhance viral entry

Coagulopathy is a significant aspect of morbidity in COVID-19 patients. The clotting cascade is propagated by a series of proteases, including factor Xa and thrombin. While certain host proteases, including TMPRSS2 and furin, are known to be important for cleavage activation of SARS-CoV-2 spike to promote viral entry in the respiratory tract, other proteases may also contribute. Using biochemical and cell-based assays, we demonstrate that factor Xa and thrombin can also directly cleave SARS-CoV-2 spike, enhancing infection at the stage of viral entry. Coagulation factors increased SARS-CoV-2 infection in human lung organoids. A drug-repurposing screen identified a subset of protease inhibitors that promiscuously inhibited spike cleavage by both transmembrane serine proteases and coagulation factors. The mechanism of the protease inhibitors nafamostat and camostat may extend beyond inhibition of TMPRSS2 to coagulation-induced spike cleavage. Anticoagulation is critical in the management of COVID-19, and early intervention could provide collateral benefit by suppressing SARS-CoV-2 viral entry. We propose a model of positive feedback whereby infection-induced hypercoagulation exacerbates SARS-CoV-2 infectivity.

System-wide transcriptome damage and tissue identity loss in COVID-19 patients

The molecular mechanisms underlying the clinical manifestations of coronavirus disease 2019 (COVID-19), and what distinguishes them from common seasonal influenza virus and other lung injury states such as acute respiratory distress syndrome, remain poorly understood. To address these challenges, we combine transcriptional profiling of 646 clinical nasopharyngeal swabs and 39 patient autopsy tissues to define body-wide transcriptome changes in response to COVID-19. We then match these data with spatial protein and expression profiling across 357 tissue sections from 16 representative patient lung samples and identify tissue-compartment-specific damage wrought by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, evident as a function of varying viral loads during the clinical course of infection and tissue-type-specific expression states. Overall, our findings reveal a systemic disruption of canonical cellular and transcriptional pathways across all tissues, which can inform subsequent studies to combat the mortality of COVID-19 and to better understand the molecular dynamics of lethal SARS-CoV-2 and other respiratory infections.

Disulfiram inhibits neutrophil extracellular trap formation protecting rodents from acute lung injury and SARS-CoV-2 infection

Severe acute lung injury has few treatment options and a high mortality rate. Upon injury, neutrophils infiltrate the lungs and form neutrophil extracellular traps (NETs), damaging the lungs and driving an exacerbated immune response. Unfortunately, no drug preventing NET formation has completed clinical development. Here, we report that disulfiram — an FDA-approved drug for alcohol use disorder — dramatically reduced NETs, increased survival, improved blood oxygenation, and reduced lung edema in a transfusion-related acute lung injury (TRALI) mouse model. We then tested whether disulfiram could confer protection in the context of SARS-CoV-2 infection, as NETs are elevated in patients with severe COVID-19. In SARS-CoV-2–infected golden hamsters, disulfiram reduced NETs and perivascular fibrosis in the lungs, and it downregulated innate immune and complement/coagulation pathways, suggesting that it could be beneficial for patients with COVID-19. In conclusion, an existing FDA-approved drug can block NET formation and improve disease course in 2 rodent models of lung injury for which treatment options are limited.

Hyperglycemia in acute COVID-19 is characterized by insulin resistance and adipose tissue infectivity by SARS-CoV-2

Individuals infected with SARS-CoV-2 who also display hyperglycemia suffer from longer hospital stays, higher risk of developing acute respiratory distress syndrome (ARDS), and increased mortality. Nevertheless, the pathophysiological mechanism of hyperglycemia in COVID-19 remains poorly characterized. Here, we show that hyperglycemia is similarly prevalent among patients with ARDS independent of COVID-19 status. Yet among patients with ARDS and COVID-19, insulin resistance is the prevalent cause of hyperglycemia, independent of glucocorticoid treatment, which is unlike patients with ARDS but without COVID-19, where pancreatic beta cell failure predominates. A screen of glucoregulatory hormones revealed lower levels of adiponectin in patients with COVID-19. Hamsters infected with SARS-CoV-2 demonstrated a strong antiviral gene expression program in the adipose tissue and diminished expression of adiponectin. Moreover, we show that SARS-CoV-2 can infect adipocytes. Together these data suggest that SARS-CoV-2 may trigger adipose tissue dysfunction to drive insulin resistance and adverse outcomes in acute COVID-19.

Cardiomyocytes recruit monocytes upon SARS-CoV-2 infection by secreting CCL2

Heart injury has been reported in up to 20% of COVID-19 patients, yet the cause of myocardial histopathology remains unknown. Here, using an established in vivo hamster model, we demonstrate that SARS-CoV-2 can be detected in cardiomyocytes of infected animals. Furthermore, we found damaged cardiomyocytes in hamsters and COVID-19 autopsy samples. To explore the mechanism, we show that both human pluripotent stem cell-derived cardiomyocytes (hPSC-derived CMs) and adult cardiomyocytes (CMs) can be productively infected by SARS-CoV-2, leading to secretion of the monocyte chemoattractant cytokine CCL2 and subsequent monocyte recruitment. Increased CCL2 expression and monocyte infiltration was also observed in the hearts of infected hamsters. Although infected CMs suffer damage, we find that the presence of macrophages significantly reduces SARS-CoV-2-infected CMs. Overall, our study provides direct evidence that SARS-CoV-2 infects CMs in vivo and suggests a mechanism of immune cell infiltration and histopathology in heart tissues of COVID-19 patients.

SARS-CoV-2 infection induces beta cell transdifferentiation

Recent clinical data have suggested a correlation between coronavirus disease 2019 (COVID-19) and diabetes. Here, we describe the detection of SARS-CoV-2 viral antigen in pancreatic beta cells in autopsy samples from individuals with COVID-19. Single-cell RNA sequencing and immunostaining from ex vivo infections confirmed that multiple types of pancreatic islet cells were susceptible to SARS-CoV-2, eliciting a cellular stress response and the induction of chemokines. Upon SARS-CoV-2 infection, beta cells showed a lower expression of insulin and a higher expression of alpha and acinar cell markers, including glucagon and trypsin1, respectively, suggesting cellular transdifferentiation. Trajectory analysis indicated that SARS-CoV-2 induced eIF2-pathway-mediated beta cell transdifferentiation, a phenotype that could be reversed with trans-integrated stress response inhibitor (trans-ISRIB). Altogether, this study demonstrates an example of SARS-CoV-2 infection causing cell fate change, which provides further insight into the pathomechanisms of COVID-19.

An Immuno-Cardiac Model for Macrophage-Mediated Inflammation in COVID-19 Hearts

[Figure: see text].

SARS-CoV-2 Infects Syncytiotrophoblast and Activates Inflammatory Responses in the Placenta

SARS-CoV-2 infection during pregnancy leads to an increased risk of adverse pregnancy outcomes. Although the placenta itself can be a target of virus infection, most neonates are virus free and are born healthy or recover quickly. Here, we investigated the impact of SARS-CoV-2 infection on the placenta from a cohort of women who were infected late during pregnancy and had tested nasal swab positive for SARS-CoV-2 by qRT-PCR at delivery. SARS-CoV-2 genomic and subgenomic RNA was detected in 23 out of 54 placentas. Two placentas with high virus content were obtained from mothers who presented with severe COVID-19 and whose pregnancies resulted in adverse outcomes for the fetuses, including intrauterine fetal demise and a preterm delivered baby still in newborn intensive care. Examination of the placental samples with high virus content showed efficient SARS-CoV-2 infection, using RNA in situ hybridization to detect genomic and replicating viral RNA, and immunohistochemistry to detect SARS-CoV-2 nucleocapsid protein. Infection was restricted to syncytiotrophoblast cells that envelope the fetal chorionic villi and are in direct contact with maternal blood. The infected placentas displayed massive infiltration of maternal immune cells including macrophages into intervillous spaces, potentially contributing to inflammation of the tissue. Ex vivo infection of placental cultures with SARS-CoV-2 or with SARS-CoV-2 spike (S) protein pseudotyped lentivirus targeted mostly syncytiotrophoblast and in rare events endothelial cells. Infection was reduced by using blocking antibodies against ACE2 and against Neuropilin 1, suggesting that SARS-CoV-2 may utilize alternative receptors for entry into placental cells.

SARS-CoV-2 Infection Causes Dopaminergic Neuron Senescence

COVID-19 patients commonly present with neurological signs of central nervous system (CNS)1-3 and/or peripheral nervous system dysfunction4. However, which neural cells are permissive to infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been controversial. Here, we show that midbrain dopamine (DA) neurons derived from human pluripotent stem cells (hPSCs) are selectively permissive to SARS-CoV-2 infection both in vitro and upon transplantation in vivo, and that SARS-CoV-2 infection triggers a DA neuron inflammatory and cellular senescence response. A high-throughput screen in hPSC-derived DA neurons identified several FDA approved drugs, including riluzole, metformin, and imatinib, that can rescue the cellular senescence phenotype and prevent SARS-CoV-2 infection. RNA-seq analysis of human ventral midbrain tissue from COVID-19 patients, using formalin-fixed paraffin-embedded autopsy samples, confirmed the induction of an inflammatory and cellular senescence signature and identified low levels of SARS-CoV-2 transcripts. Our findings demonstrate that hPSC-derived DA neurons can serve as a disease model to study neuronal susceptibility to SARS-CoV-2 and to identify candidate neuroprotective drugs for COVID-19 patients. The susceptibility of hPSC-derived DA neurons to SARS-CoV-2 and the observed inflammatory and senescence transcriptional responses suggest the need for careful, long-term monitoring of neurological problems in COVID-19 patients.

Cell and Tissue Therapy for the Treatment of Chronic Liver Disease

Liver disease is an important clinical problem, impacting 600 million people worldwide. It is the 11th-leading cause of death in the world. Despite constant improvement in treatment and diagnostics, the aging population and accumulated risk factors led to increased morbidity due to nonalcoholic fatty liver disease and steatohepatitis. Liver transplantation, first established in the 1960s, is the second-most-common solid organ transplantation and is the gold standard for the treatment of liver failure. However, less than 10% of the global need for liver transplantation is met at the current rates of transplantation due to the paucity of available organs. Cell- and tissue-based therapies present an alternative to organ transplantation. This review surveys the approaches and tools that have been developed, discusses the distinctive challenges that exist for cell- and tissue-based therapies, and examines the future directions of regenerative therapies for the treatment of liver disease.

The spatial landscape of lung pathology during COVID-19 progression

Recent studies have provided insights into the pathology of and immune response to COVID-191-8. However, a thorough investigation of the interplay between infected cells and the immune system at sites of infection has been lacking. Here we use high-parameter imaging mass cytometry9 that targets the expression of 36 proteins to investigate the cellular composition and spatial architecture of acute lung injury in humans (including injuries derived from SARS-CoV-2 infection) at single-cell resolution. These spatially resolved single-cell data unravel the disordered structure of the infected and injured lung, alongside the distribution of extensive immune infiltration. Neutrophil and macrophage infiltration are hallmarks of bacterial pneumonia and COVID-19, respectively. We provide evidence that SARS-CoV-2 infects predominantly alveolar epithelial cells and induces a localized hyperinflammatory cell state that is associated with lung damage. We leverage the temporal range of fatal outcomes of COVID-19 in relation to the onset of symptoms, which reveals increased macrophage extravasation and increased numbers of mesenchymal cells and fibroblasts concomitant with increased proximity between these cell types as the disease progresses-possibly as a result of attempts to repair the damaged lung tissue. Our data enable us to develop a biologically interpretable landscape of lung pathology from a structural, immunological and clinical standpoint. We use this landscape to characterize the pathophysiology of the human lung from its macroscopic presentation to the single-cell level, which provides an important basis for understanding COVID-19 and lung pathology in general.

Hyperglycemia in Acute COVID-19 is Characterized by Adipose Tissue Dysfunction and Insulin Resistance

COVID-19 has proven to be a metabolic disease resulting in adverse outcomes in individuals with diabetes or obesity. Patients infected with SARS-CoV-2 and hyperglycemia suffer from longer hospital stays, higher risk of developing acute respiratory distress syndrome (ARDS), and increased mortality compared to those who do not develop hyperglycemia. Nevertheless, the pathophysiological mechanism(s) of hyperglycemia in COVID-19 remains poorly characterized. Here we show that insulin resistance rather than pancreatic beta cell failure is the prevalent cause of hyperglycemia in COVID-19 patients with ARDS, independent of glucocorticoid treatment. A screen of protein hormones that regulate glucose homeostasis reveals that the insulin sensitizing adipokine adiponectin is reduced in hyperglycemic COVID-19 patients. Hamsters infected with SARS-CoV-2 also have diminished expression of adiponectin. Together these data suggest that adipose tissue dysfunction may be a driver of insulin resistance and adverse outcomes in acute COVID-19.

Systemic Tissue and Cellular Disruption from SARS-CoV-2 Infection revealed in COVID-19 Autopsies and Spatial Omics Tissue Maps

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus has infected over 115 million people and caused over 2.5 million deaths worldwide. Yet, the molecular mechanisms underlying the clinical manifestations of COVID-19, as well as what distinguishes them from common seasonal influenza virus and other lung injury states such as Acute Respiratory Distress Syndrome (ARDS), remains poorly understood. To address these challenges, we combined transcriptional profiling of 646 clinical nasopharyngeal swabs and 39 patient autopsy tissues, matched with spatial protein and expression profiling (GeoMx) across 357 tissue sections. These results define both body-wide and tissue-specific (heart, liver, lung, kidney, and lymph nodes) damage wrought by the SARS-CoV-2 infection, evident as a function of varying viral load (high vs. low) during the course of infection and specific, transcriptional dysregulation in splicing isoforms, T cell receptor expression, and cellular expression states. In particular, cardiac and lung tissues revealed the largest degree of splicing isoform switching and cell expression state loss. Overall, these findings reveal a systemic disruption of cellular and transcriptional pathways from COVID-19 across all tissues, which can inform subsequent studies to combat the mortality of COVID-19, as well to better understand the molecular dynamics of lethal SARS-CoV-2 infection and other viruses.

Genome-wide DNA methylation profiling of peripheral blood reveals an epigenetic signature associated with severe COVID-19

The global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a highly pathogenic RNA virus causing coronavirus disease 2019 (COVID‐19) in humans. Although most patients with COVID‐19 have mild illness and may be asymptomatic, some will develop severe pneumonia, acute respiratory distress syndrome, multi‐organ failure, and death. RNA viruses such as SARS‐CoV‐2 are capable of hijacking the epigenetic landscape of host immune cells to evade antiviral defense. Yet, there remain considerable gaps in our understanding of immune cell epigenetic changes associated with severe SARS‐CoV‐2 infection pathology. Here, we examined genome‐wide DNA methylation (DNAm) profiles of peripheral blood mononuclear cells from 9 terminally‐ill, critical COVID‐19 patients with confirmed SARS‐CoV‐2 plasma viremia compared with uninfected, hospitalized influenza, untreated primary HIV infection, and mild/moderate COVID‐19 HIV coinfected individuals. Cell‐type deconvolution analyses confirmed lymphopenia in severe COVID‐19 and revealed a high percentage of estimated neutrophils suggesting perturbations to DNAm associated with granulopoiesis. We observed a distinct DNAm signature of severe COVID‐19 characterized by hypermethylation of IFN‐related genes and hypomethylation of inflammatory genes, reinforcing observations in infection models and single‐cell transcriptional studies of severe COVID‐19. Epigenetic clock analyses revealed severe COVID‐19 was associated with an increased DNAm age and elevated mortality risk according to GrimAge, further validating the epigenetic clock as a predictor of disease and mortality risk. Our epigenetic results reveal a discovery DNAm signature of severe COVID‐19 in blood potentially useful for corroborating clinical assessments, informing pathogenic mechanisms, and revealing new therapeutic targets against SARS‐CoV‐2.

SARS-CoV-2 Infected Cardiomyocytes Recruit Monocytes by Secreting CCL2

Heart injury has been reported in up to 20% of COVID-19 patients, yet the cause of myocardial histopathology remains unknown. In order to study the cause of myocardial pathology in COVID-19 patients, we used a hamster model to determine whether following infection SARS-CoV-2, the causative agent of COVID-19, can be detected in heart tissues. Here, we clearly demonstrate that viral RNA and nucleocapsid protein is present in cardiomyocytes in the hearts of infected hamsters. Interestingly, functional cardiomyocyte associated gene expression was decreased in infected hamster hearts, corresponding to an increase in reactive oxygen species (ROS). This data using an animal model was further validated using autopsy heart samples of COVID-19 patients. Moreover, we show that both human pluripotent stem cell-derived cardiomyocytes (hPSC-derived CMs) and adult cardiomyocytes (CMs) can be infected by SARS-CoV-2 and that CCL2 is secreted upon SARS-CoV-2 infection, leading to monocyte recruitment. Increased CCL2 expression and macrophage infiltration was also observed in the hearts of infected hamsters. Using single cell RNA-seq, we also show that macrophages are able to decrease SARS-CoV-2 infection of CMs. Overall, our study provides direct evidence that SARS-CoV-2 infects CMs in vivo and proposes a mechanism of immune-cell infiltration and pathology in heart tissue of COVID-19 patients.

A Human Pluripotent Stem Cell-based Platform to Study SARS-CoV-2 Tropism and Model Virus Infection in Human Cells and Organoids

SARS-CoV-2 has caused the COVID-19 pandemic. There is an urgent need for physiological models to study SARS-CoV-2 infection using human disease-relevant cells. COVID-19 pathophysiology includes respiratory failure but involves other organ systems including gut, liver, heart, and pancreas. We present an experimental platform comprised of cell and organoid derivatives from human pluripotent stem cells (hPSCs). A Spike-enabled pseudo-entry virus infects pancreatic endocrine cells, liver organoids, cardiomyocytes, and dopaminergic neurons. Recent clinical studies show a strong association with COVID-19 and diabetes. We find that human pancreatic beta cells and liver organoids are highly permissive to SARS-CoV-2 infection, further validated using adult primary human islets and adult hepatocyte and cholangiocyte organoids. SARS-CoV-2 infection caused striking expression of chemokines, as also seen in primary human COVID-19 pulmonary autopsy samples. hPSC-derived cells/organoids provide valuable models for understanding the cellular responses of human tissues to SARS-CoV-2 infection and for disease modeling of COVID-19.

Segmenting and tracking the left ventricle by learning the dynamics in cardiac images

Having accurate left ventricle (LV) segmentations across a cardiac cycle provides useful quantitative (e.g. ejection fraction) and qualitative information for diagnosis of certain heart conditions. Existing LV segmentation techniques are founded mostly upon algorithms for segmenting static images. In order to exploit the dynamic structure of the heart in a principled manner, we approach the problem of LV segmentation as a recursive estimation problem. In our framework, LV boundaries constitute the dynamic system state to be estimated, and a sequence of observed cardiac images constitute the data. By formulating the problem as one of state estimation, the segmentation at each particular time is based not only on the data observed at that instant, but also on predictions based on past segmentations. This requires a dynamical system model of the LV, which we propose to learn from training data through an information-theoretic approach. To incorporate the learned dynamic model into our segmentation framework and obtain predictions, we use ideas from particle filtering. Our framework uses a curve evolution method to combine such predictions with the observed images to estimate the LV boundaries at each time. We demonstrate the effectiveness of the proposed approach on a large set of cardiac images. We observe that our approach provides more accurate segmentations than those from static image segmentation techniques, especially when the observed data are of limited quality.

ECG changes in asphyxia neonatorum

Twenty five asphyxiated neonates had ECG changes consistent with degree of asphyxia. Equivocal changes were found in mild asphyxia and changes suggestive of myocardial infarction were seen with severe asphyxia. In most cases, the changes reverted to normal within two weeks signifying great ability of the neonatal heart to withstand hypoxic insult. Four babies with severe asphyxia having ECG changes suggestive of acute myocardial infarction expired within 48 hours of birth.

Falciparum malaria

We analysed cases of hematologically proved cases of Plasmodium falciparum malaria encountered from July 1984 to Dec 1985 in a military hospital. The age range was 3 days to 10 years. Majority presented with classical symptom of fever (92.7%). Others presented with gastrointestinal (7.3%), hepatic (4.5%), central nervous system (7.3%) and respiratory (3.6%) symptoms. Anemia was found in 36.4%. Hepatosplenomegaly was present in majority of the cases. The rare findings were polyarthritis, rash, urticaria and cerebellar features. All cases responded to chloroquine or quinine. No resistance to drugs was found and there was no mortality.

Falciparum malaria--present day problems. An experience with 425 cases

Clinical details and present day problems encountered in 425 cases of falciparum malaria (PF) are reported. 10.11% had taken chloroquine prior to reporting to us. Parasitic count done in 23.05% cases lacked correlation with severity of disease. Pattern of fever varied markedly but 5.4% were afebrile throughout and presented only with bodyache and malaise. Apyrexial spell was noted in 5.64%. 28.70% had typical facial looks of anaemia and sallow complexion. Cerebral symptoms were noted in 3.05%. Other symptoms were severe headache 33.4%, pain abdomen 3.29%, gastroenteritis 5.64%, jaundice 2.58% and bronchitis in 7.50%. We encountered subconjunctival haemorrhages with purpura and/or urticaria in four cases, symptoms suggestive of shock lung in 3, pulmonary oedema in 2, severe anaemia (HB less than 4 g%) in seven pregnant ladies, extrapyramidal symptoms in follow up period in 5 and congenital malaria in 2 cases. 83.25% were cured with chloroquine and oxytetracycline. 8.47% (who deteriorated despite the above treatment) were treated with quinine for 6 days. 5.17% (with severe disease) were also given quinine as first line drug. 2.82% (unresponsive to chloroquine and oxytetracycline but with mild disease) were treated with pyrimethamine-sulphamezathine combination for 5 days. One case who did not respond to quinine was treated with quinidine. Recrudescence was seen in 3.67% of patients treated with chloroquine and oxytetracycline. There was no case with renal failure, haemolysis due to G6PD deficiency and black water fever. There was only one death (0.23%) in our series. Self-medication, haphazard therapy and the slogan "Fever may be malaria-take chloroquine" can lead to problems in falciparum malaria.