Autopsy Findings in 32 Patients with COVID-19: A Single-Institution Experience

Pathology of COVID-19 Lung Disease

The pathology of severe COVID-19 lung injury is predominantly diffuse alveolar damage, with other reported patterns including acute fibrinous organizing pneumonia, organizing pneumonia, and bronchiolitis. Lung injury was caused by primary viral injury, exaggerated immune responses, and superinfection with bacteria and fungi. Although fatality rates have decreased from the early phases of the pandemic, persistent pulmonary dysfunction occurs and its pathogenesis remains to be fully elucidated.

COVID-19: Not a thrombotic disease but a thromboinflammatory disease

While Coronavirus Disease in 2019 (COVID-19) may no longer be classified as a global public health emergency, it still poses a significant risk at least due to its association with thrombotic events. This study aims to reaffirm our previous hypothesis that COVID-19 is fundamentally a thrombotic disease. To accomplish this, we have undertaken an extensive literature review focused on assessing the comprehensive impact of COVID-19 on the entire hemostatic system. Our analysis revealed that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection significantly enhances the initiation of thrombin generation. However, it is noteworthy that the thrombin generation may be modulated by specific anticoagulants present in patients' plasma. Consequently, higher levels of fibrinogen appear to play a more pivotal role in promoting coagulation in COVID-19, as opposed to thrombin generation. Furthermore, the viral infection can stimulate platelet activation either through widespread dissemination from the lungs to other organs or localized effects on platelets themselves. An imbalance between Von Willebrand Factor (VWF) and ADAMTS-13 also contributes to an exaggerated platelet response in this disease, in addition to elevated D-dimer levels, coupled with a significant increase in fibrin viscoelasticity. This paradoxical phenotype has been identified as 'fibrinolysis shutdown'. To clarify the pathogenesis underlying these hemostatic disorders in COVID-19, we also examined published data, tracing the reaction process of relevant proteins and cells, from ACE2-dependent viral invasion, through induced tissue inflammation, endothelial injury, and innate immune responses, to occurrence of thrombotic events. We therefrom understand that COVID-19 should no longer be viewed as a thrombotic disease solely based on abnormalities in fibrin clot formation and proteolysis. Instead, it should be regarded as a thromboinflammatory disorder, incorporating both classical elements of cellular inflammation and their intricate interactions with the specific coagulopathy.

Sarcoidosis-related autoimmune inflammation in COVID-19 convalescent patients

Currently, there are a large number of reports about the development of autoimmune conditions after COVID-19. Also, there have been cases of sarcoid-like granulomas in convalescents as a part of the post-COVID-19 syndrome. Since one of the etiological theories of sarcoidosis considers it to be an autoimmune disease, we decided to study changes in the adaptive humoral immune response in sarcoidosis and SARS-CoV-2 infection and to find out whether COVID-19 can provoke the development of sarcoidosis. This review discusses histological changes in lymphoid organs in sarcoidosis and COVID-19, changes in B cell subpopulations, T-follicular helper cells (Tfh), and T-follicular regulatory cells (Tfr), and analyzes various autoantibodies detected in these pathologies. Based on the data studied, we concluded that SARS-CoV-2 infection may cause the development of autoimmune pathologies, in particular contributing to the onset of sarcoidosis in convalescents.

COVID-19 in Children: Molecular Profile and Pathological Features

Although the World Health Organization has declared the end of the COVID-19 pandemic, doctors continue to register new cases of the disease among both adults and children. Unfortunately, the course of COVID-19 in children can have a severe form, with death being a potential outcome. The absence of published works discussing the pathological morphology of COVID-19 in children prevents the objective analysis of the disease's pathogenesis, including among the adult population. In this vein, the objective of our study is to identify the morphological features of the lungs' involvement and evaluate virus-host interactions in the case of COVID-19 in patients at a pediatric medical practice. We present the results of the study of the lungs of three children who died due to COVID-19, highlighting the predominant involvement of their respiratory organs at different stages of the disease (5, 21, and 50 days). This article presents data obtained from histopathological and immunohistochemical investigations, taking into account the results of clinical and laboratory indicators and intravital and postmortem SARS-CoV-2 PCR investigations. The common finding of all of the examined COVID-19 cases is the involvement of the endothelium in microcirculation vessels, which are considered to be a primary target of various pathogenic influencing factors. We also discuss both the significance of apoptosis as a result of virus-host interactions and the most likely cause of endothelium cell destruction. The results of this study could be useful for the development of endothelium-protective therapy to prevent the progression of disseminated intravascular coagulation syndrome.

Alveolar Hyperoxia and Exacerbation of Lung Injury in Critically Ill SARS-CoV-2 Pneumonia

Acute hypoxic respiratory failure (AHRF) is a prominent feature of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) critical illness. The severity of gas exchange impairment correlates with worse prognosis, and AHRF requiring mechanical ventilation is associated with substantial mortality. Persistent impaired gas exchange leading to hypoxemia often warrants the prolonged administration of a high fraction of inspired oxygen (FiO2). In SARS-CoV-2 AHRF, systemic vasculopathy with lung microthrombosis and microangiopathy further exacerbates poor gas exchange due to alveolar inflammation and oedema. Capillary congestion with microthrombosis is a common autopsy finding in the lungs of patients who die with coronavirus disease 2019 (COVID-19)-associated acute respiratory distress syndrome. The need for a high FiO2 to normalise arterial hypoxemia and tissue hypoxia can result in alveolar hyperoxia. This in turn can lead to local alveolar oxidative stress with associated inflammation, alveolar epithelial cell apoptosis, surfactant dysfunction, pulmonary vascular abnormalities, resorption atelectasis, and impairment of innate immunity predisposing to secondary bacterial infections. While oxygen is a life-saving treatment, alveolar hyperoxia may exacerbate pre-existing lung injury. In this review, we provide a summary of oxygen toxicity mechanisms, evaluating the consequences of alveolar hyperoxia in COVID-19 and propose established and potential exploratory treatment pathways to minimise alveolar hyperoxia.

Integrated Transcriptomics and Network Analysis of Potential Mechanisms and Health Effects of Convalescent COVID-19 Patients

Coronaviral disease 2019 (COVID-19) is a recent pandemic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, there are still cases of COVID-19 around the world that can develop into persistent symptoms after discharge. The constellation of symptoms, termed long COVID, persists for months and can lead to various diseases such as lung inflammation and cardiovascular disease, which may lead to considerable financial burden and possible risk to human health. Moreover, the molecular mechanisms underlying the post-pandemic syndrome of COVID-19 remain unclear. In this study, we aimed to explore the molecular mechanism, disease association, and possible health risks in convalescent COVID-19 patients. Gene expression data from a human convalescent COVID-19 data set was compared with a data set from healthy normal individuals in order to identify differentially expressed genes (DEGs). To determine biological function and potential pathway alterations, the GO and KEGG databases were used to analyze the DEGs. Disease association, tissue, and organ-specific analyses were used to identify possible health effects. A total of 250 DEGs were identified between healthy and convalescent COVID-19 subjects. The biological function alterations identified revealed cytokine interactions and increased inflammation through NF-κB1, RELA, JUN, STAT3, and SP1. Interestingly, the most significant pathways were cytokine-cytokine receptor interaction, altered lipid metabolism, and atherosclerosis that play a crucial role in convalescent COVID-19. In addition, we also found pneumonitis, dermatitis, and autoimmune diseases. Based on our study, convalescent COVID-19 is associated with inflammation in a variety of organs that could lead to autoimmune and inflammatory diseases, as well as atherosclerosis. These findings are a first step toward fully exploring the disease mechanisms in depth to understand the relationship between post-COVID-19 infection and potential health risks. This is necessary for the development of appropriate strategies for the prevention and treatment of long COVID.

Long COVID: Clinical Findings, Pathology, and Endothelial Molecular Mechanisms

Persistence of COVID-19 symptoms may follow severe acute respiratory syndrome coronavirus 2 infection. The incidence of long COVID increases with the severity of acute disease, but even mild disease can be associated with sequelae. The symptoms vary widely, with fatigue, shortness of breath, and cognitive dysfunction the most common. Abnormalities of multiple organs have been documented, and histopathology has revealed widespread microthrombi. Elevated levels of complement are present in acute COVID-19 patients and may persist at lower levels in long COVID. Evidence supports complement activation, with endotheliopathy-associated disease as the molecular mechanism causing both acute and long COVID.

Autopsy findings from patients diagnosed with COVID-19 demonstrate unique morphological patterns in bone marrow and lymph node

AIMS

The identification of haemophagocytosis in bone marrow (BM) is recurrently identified in patients with severe COVID-19. These initial COVID-19 autopsy studies have afforded valuable insight into the pathophysiology of this disease; however, only a limited number of case series have focused on lymphoid or haematopoietic tissues.

METHODS

BM and lymph node (LN) specimens were obtained from adult autopsies performed between 1 April 2020 and 1 June 2020, for which the decedent had tested positive for SARS-CoV-2. Tissue sections (H&E, CD3, CD20, CD21, CD138, CD163, MUM1, kappa/lambda light chains in situ hybridisation) were examined by two haematopathologists, who recorded morphological features in a blinded fashion. Haemophagocytic lymphohistiocytosis (HLH) was assessed based on HLH 2004 criteria.

RESULTS

The BM demonstrated a haemophagocytic pattern in 9 out of 25 patients (36%). The HLH pattern was associated with longer hospitalisation, BM plasmacytosis, LN follicular hyperplasia and lower aspartate aminotransferase (AST), as well as ferritin at demise. LN examination showed increased plasmacytoid cells in 20 of 25 patients (80%). This pattern was associated with a low absolute monocyte count at diagnosis, lower white cell count and lower absolute neutrophil count at demise, and lower ferritin and AST at demise.

CONCLUSIONS

Autopsy results demonstrate distinct morphological patterns in BM, with or without haemophagocytic macrophages, and in LN, with or without increased plasmacytoid cells. Since only a minority of patients met diagnostic criteria for HLH, the observed BM haemophagocytic macrophages may be more indicative of an overall inflammatory state.

COVID-19-related hyperglycemia is associated with infection of hepatocytes and stimulation of gluconeogenesis

Occurrence of hyperglycemia upon infection is associated with worse clinical outcome in COVID-19 patients. However, it is still unknown whether SARS-CoV-2 directly triggers hyperglycemia. Herein, we interrogated whether and how SARS-CoV-2 causes hyperglycemia by infecting hepatocytes and increasing glucose production. We performed a retrospective cohort study including patients that were admitted at a hospital with suspicion of COVID-19. Clinical and laboratory data were collected from the chart records and daily blood glucose values were analyzed to test the hypothesis on whether COVID-19 was independently associated with hyperglycemia. Blood glucose was collected from a subgroup of nondiabetic patients to assess pancreatic hormones. Postmortem liver biopsies were collected to assess the presence of SARS-CoV-2 and its transporters in hepatocytes. In human hepatocytes, we studied the mechanistic bases of SARS-CoV-2 entrance and its gluconeogenic effect. SARS-CoV-2 infection was independently associated with hyperglycemia, regardless of diabetic history and beta cell function. We detected replicating viruses in human hepatocytes from postmortem liver biopsies and in primary hepatocytes. We found that SARS-CoV-2 variants infected human hepatocytes in vitro with different susceptibility. SARS-CoV-2 infection in hepatocytes yields the release of new infectious viral particles, though not causing cell damage. We showed that infected hepatocytes increase glucose production and this is associated with induction of PEPCK activity. Furthermore, our results demonstrate that SARS-CoV-2 entry in hepatocytes occurs partially through ACE2- and GRP78-dependent mechanisms. SARS-CoV-2 infects and replicates in hepatocytes and exerts a PEPCK-dependent gluconeogenic effect in these cells that potentially is a key cause of hyperglycemia in infected patients.

Cardio-Pulmonary Histopathology with Clinical Correlations of Deceased Patients with COVID-19: A Case Series in Tehran, Iran

BACKGROUND

SARS-CoV-2 may affect vital organs. The present study investigated the histopathology of pulmonary and cardiac tissues with clinical correlation in deceased patients with COVID-19.

METHODS

We obtained pulmonary and cardiac tissues from 30 deceased patients with COVID-19 in Tehran, Iran, from January to May 2021. Sampling was performed through a percutaneous needle biopsy. After slide preparation, two expert pathologists studied them. We assessed the correlation between clinical and pathological data by Fisher's exact test.

RESULTS

The mean age of the patients was 73.8±13.4 years, and the male-to-female ratio was 23/7. The most common underlying disease was hypertension (HTN) in 25 patients (83%). Fifty-five tissue samples were achieved, including 28 pulmonary and 27 cardiac samples. Our results showed that all patients (100%) developed diffuse alveolar damage (DAD), and 26 (93%) developed hyaline membrane formation. The most common phase of DAD was the exudative-proliferative phase in 16 (57.1%). Three cardiac samples (11%) revealed myocarditis, and seven (26%) showed cardiomyocyte hypertrophy. In univariate analysis using Fischer's exact test, myocarditis had significant relationships with C-reactive protein (CRP) levels higher than 80 mg/dL (P=0.008) and elevated cardiac troponin levels higher than two-fold (P=0.01).

CONCLUSION

COVID-19 can affect the major vital organs. However, only myocarditis had a significant relationship with the circulating levels of inflammatory factors.

COVID-19 and Sickle Cell Disease: Two Independent Risk Factors for Venous Thromboembolism

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been widely documented as a multi-systemic illness and associated with an increased incidence of thromboses. Likewise, sickle cell disease (SCD) is a hematologic disease responsible for widespread effects on the vasculature and is also associated with elevated thrombotic risk. In this review, we examine the incidence rates of venous thromboembolism (VTE) in SCD and COVID-19 independently and review the mechanisms of coagulopathy associated with both diseases. We describe the possible associations and commonalities between VTE mechanisms, as both diseases cause widespread inflammation that influences each tenet of Virchow's triad. We also discuss current anticoagulation guideline recommendations for the prevention of VTE events in each of these diseases. We report on current literature to date describing rates of VTE in SCD-COVID-19 patients and outline prospective areas of research to further understand the possible synergistic influence of coagulopathy in these patients. The association between SCD and COVID-19 remains a largely under-researched area of coagulopathy in current hematology and thrombotic literature, and our report lays out potential future prospects in the field.

The Spectrum of Digestive Tract Histopathologic Findings in the Setting of Severe Acute Respiratory Syndrome Coronavirus-2 Infection: What Pathologists Need to Know

Although the novel severe acute respiratory syndrome coronavirus-2 is known primarily to affect the respiratory system, current evidence supports its capability to infect and induce gastrointestinal tract injury. Data describing the histopathologic alterations of the digestive system in patients infected with severe acute respiratory syndrome coronavirus-2 are becoming more detailed, as the number of studies is increasing and the quality of our insight into the infection and the histopathologic findings is improving. This review highlights the range of pathologic findings that could be observed in gastrointestinal specimens from patients infected with coronavirus disease 2019 and the potential underlying pathogenetic mechanisms of this disease.

A Systematic Review of Lung Autopsy Findings in Elderly Patients after SARS-CoV-2 Infection

Although COVID-19 may cause various and multiorgan diseases, few research studies have examined the postmortem pathological findings of SARS-CoV-2-infected individuals who died. Active autopsy results may be crucial for understanding how COVID-19 infection operates and preventing severe effects. In contrast to younger persons, however, the patient's age, lifestyle, and concomitant comorbidities might alter the morpho-pathological aspects of the damaged lungs. Through a systematic analysis of the available literature until December 2022, we aimed to provide a thorough picture of the histopathological characteristics of the lungs in patients older than 70 years who died of COVID-19. A thorough search was conducted on three electronic databases (PubMed, Scopus, and Web of Science), including 18 studies and a total of 478 autopsies performed. It was observed that the average age of patients was 75.6 years, of which 65.4% were men. COPD was identified in an average of 16.7% of all patients. Autopsy findings indicated significantly heavier lungs, with an average weight of the right lung of 1103 g, while the left lung mass had an average weight of 848 g. Diffuse alveolar damage was a main finding in 67.2% of all autopsies, while pulmonary edema had a prevalence of between 50% and 70%. Thrombosis was also a significant finding, while some studies described focal and extensive pulmonary infarctions in 72.7% of elderly patients. Pneumonia and bronchopneumonia were observed, with a prevalence ranging from 47.6% to 89.5%. Other important findings described in less detail comprise hyaline membranes, the proliferation of pneumocytes and fibroblasts, extensive suppurative bronchopneumonic infiltrates, intra-alveolar edema, thickened alveolar septa, desquamation of pneumocytes, alveolar infiltrates, multinucleated giant cells, and intranuclear inclusion bodies. These findings should be corroborated with children's and adults' autopsies. Postmortem examination as a technique for studying the microscopic and macroscopic features of the lungs might lead to a better knowledge of COVID-19 pathogenesis, diagnosis, and treatment, hence enhancing elderly patient care.

Liver Injury Associated with COVID-19 Infection: Pathogenesis, Histopathology, Prognosis, and Treatment

Liver injury occurs frequently as a consequence of SARS-CoV-2 infection. Direct infection of the liver leads to hepatic impairment with elevated transaminases. In addition, severe COVID-19 is characterized by cytokine release syndrome, which may initiate or exacerbate liver injury. In patients with cirrhosis, SARS-CoV-2 infection is associated with acute-on-chronic liver failure. The Middle East and North Africa (MENA) region is one of the world's regions characterized by a high prevalence of chronic liver diseases. Both parenchymal and vascular types of injury contribute to liver failure in COVID-19, with a myriad of pro-inflammatory cytokines playing a major role in perpetuating liver injury. Additionally, hypoxia and coagulopathy complicate such a condition. This review discusses the risk factors, and the underlying causes of impaired liver functions in COVID-19, with a focus on key players in the pathogenesis of liver injury. It also highlights the histopathological changes encountered in postmortem liver tissues as well as potential predictors and prognostic factors of such injury, in addition to the management strategies to ameliorate liver damage.

Putrefaction in the pandemic: a comparative study of the frequency of advanced decomposition change in coronial autopsies since the start of the COVID-19 pandemic

AIMS

The aim of this study is to evaluate whether there has been a significant change in the frequency of markedly decomposed bodies having coronial autopsies since the UK's first COVID-19 lockdown.

METHODS

We compared coronial autopsies (n=263) performed by one pathologist at a central London mortuary in the 1 year before and after 23 March 2020 by analysing their autopsy reports and coronial documentation.

RESULTS

We have shown that there has been a significant increase of 70.5% (p=0.001) in the frequency of markedly decomposed bodies having coronial autopsies since the first lockdown. This is associated with a 38% increase (p=0.0001) in the rate of those dying at home and a 52.4% decrease (p=0.00003) in the rate of those dying in hospital who go on to have a coronial autopsy in our facility. Our results suggest that the most significant factor behind the increased frequency in advanced decomposition change since the first lockdown is this increase in coronial autopsies for deaths at home relative to deaths in hospital.

CONCLUSION

Our results support the idea that perimortem social isolation will lead to an increased frequency of advanced decomposition changes seen at autopsy. We suggest that it could be possible to use the frequency of advanced postmortem decomposition change in a population as a surrogate marker for social isolation in future studies. Our study also illustrates a changing environment where the increasing prevalence of postmortem decomposition changes could affect the accuracy of autopsy reports and the medicolegal consequences thereof.

Animal models and SARS-CoV-2-induced pulmonary and neurological injuries

Laboratory animals are essential mainly for experiments aiming to study pathogenesis and evaluate antivirals and vaccines against emerging human infectious diseases. Preclinical studies of coronavirus disease 19 (COVID-19) pathogenesis have used several animal species as models: transgenic human ACE2 mice (K18 mice), inbred BALB/c or C57BL/6N mice, ferrets, minks, domestic cats and dogs, hamsters, and macaques. However, the choice of an animal model relies on several limitations. Besides the host susceptibility, the researcher's experience with animal model management and the correct interpretation of clinical and laboratory records are crucial to succeed in preclinical translational research. Here, we summarise pathological and clinical findings correlated with virological data and immunological changes observed from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) experimental infections using different well-established SARS-CoV-2 animal model species. This essay aims to critically evaluate the current state of animal model translation to clinical data, as described in the human SARS-CoV-2 infection.

Liver pathology in COVID-19 related death and leading role of autopsy in the pandemic

BACKGROUND

Information on liver involvement in patients with coronavirus disease 2019 is currently fragmented.

AIM

To highlight the pathological changes found during the autopsy of severe acute respiratory syndrome coronavirus 2 positive patients.

METHODS

A systematic literature search on PubMed was carried out until June 21, 2022.

RESULTS

A literature review reveals that pre-existing liver disease and elevation of liver enzyme in these patients are not common; liver enzyme elevations tend to be seen in those in critical conditions. Despite the poor expression of viral receptors in the liver, it seems that the virus is able to infect this organ and therefore cause liver damage. Unfortunately, to date, the search for the virus inside the liver is not frequent (16% of the cases) and only a small number show the presence of the virus. In most of the autopsy cases, macroscopic assessment is lacking, while microscopic evaluation of livers has revealed the frequent presence of congestion (42.7%) and steatosis (41.6%). Less frequent is the finding of hepatic inflammation or necrosis (19%) and portal inflammation (18%). The presence of microthrombi, frequently found in the lungs, is infrequent in the liver, with only 12% of cases presenting thrombotic formations within the vascular tree.

CONCLUSION

To date, the greatest problem in interpreting these modifications remains the association of the damage with the direct action of the virus, rather than with the inflammation or alterations induced by hypoxia and hypovolemia in patients undergoing oxygen therapy and decompensated patients.

Pathogenesis and histological changes of nephropathy associated with COVID-19

Coronavirus disease 2019 (COVID-19) can cause damage to multiple organ, not only to the lungs, but also to the kidneys. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause acute and chronic kidney disease through direct viral infection, indirect injury, and vaccination-related injury. Like lung injury, kidney injury is also an important aspect affecting the severity and prognosis of SARS-CoV-2. This article summarizes the pathogenesis, pathological manifestations, and clinical features of SARS-CoV-2 direct or indirect renal injury. Including direct injury, indirect injury, special comorbidities (receiving kidney transplantation and chronic kidney disease), and vaccine-related renal injury, and exploring the possible therapeutic effect of anti-SARS-CoV-2 therapy on renal injury. The purpose is to provide reference for understanding COVID-19-related renal injury, guiding clinical and pathological diagnosis and treatment, and evaluating prognosis.

Autopsy Findings and Inflammatory Markers in SARS-CoV-2: A Single-Center Experience

Purpose

The systemic inflammatory response related to COVID-19 can be easily investigated in living patients. Unfortunately, not every biomarker is suitable for postmortem analysis since several factors may interfere. The aim of this study was to summarize key histopathological findings within each organ system due to COVID-19 and to assess if serological inexpensive and widely available biomarkers such as CRP, IL-6, fibrinogen and d-Dimers, associated with adverse outcomes in COVID-19, can be implemented in a post-mortem assessment.

Patients and Methods

A total of 60 subjects divided in 2 groups were included. All subjects died outside a hospital setting and therefore did not receive specific or symptomatic therapies that could have modulated the inflammatory response. The first group included 45 subjects in which mandatory autopsy was performed in order to establish the cause of death and macroscopic examination of the lungs was highly suggestive of SARS-CoV-2 infection. As controls (Group 2), 20 subjects who died from polytrauma in high velocity car accidents and suicide were selected. Bronchial fluids collected during the autopsy procedure were used for the RT-PCR diagnosis of SARS-CoV-2 and serum samples were sent for analysis of IL-6, CRP, d-Dimers and fibrinogen.

Results

Compared with the control group, the subjects of the COVID-19 group were older (59±19.5 vs.38±19.15 years, p=0.0002) and had more underlying comorbidities such as hypertension (60% vs 35%, p=0.06) or were overweight (53.3% vs 30%, p=0.08). The levels of CRP, IL-6, fibrinogen and d-Dimers in postmortem plasma samples were significantly higher in COVID-19 subjects than in control group (p< 0.0001). Moreover, the level of IL-6 was significantly higher in overweight patients (r=0.52, P<0.001). In all COVID-19 subjects, the histological examination revealed features corresponding to the exudative and/or proliferative phases of diffuse alveolar damage. Large pulmonary emboli were observed in 7 cases. Gross cardiac enlargement with left ventricular hypertrophy was observed in 19 cases. The most frequent pathological finding of the central nervous system was acute/early-subacute infarction.

Conclusion

Due to the complexity of the inflammatory response, we postulate that a combination of biomarkers, rather than a single laboratory parameter, might be more effective in obtaining a reliable postmortem COVID-19 diagnosis.

Feasibility and Safety of Transbronchial Lung Cryobiopsy for Diagnosis of Acute Respiratory Failure with Mechanical Ventilation in Intensive Care Unit

BACKGROUND

Acute hypoxemic respiratory failure is common in intensive care units (ICUs). Lung biopsies may be required to make a definitive diagnosis in patients with unknown etiologies. The feasibility of transbronchial lung cryobiopsy is undetermined in patients with respiratory failure in the ICU.

METHODS

Patients who underwent bronchoscopy examinations with transbronchial lung cryobiopsy (TBLC) between July 2018 and December 2019 were retrospectively analyzed through medical chart review. The procedures were performed by well-experienced interventional pulmonologists.

RESULTS

Ten patients underwent bronchoscopy examinations with TBLC in the ICU at Chang Gung Memorial Hospital during the study period. In all patients, the diagnosis was made via pathological analysis. One patient developed pneumothorax and required chest tube placement after the procedure. None of the patients had bleeding requiring blood transfusion, and no deaths were directly related to the procedure.

CONCLUSIONS

TBLC is a feasible technique to obtain lung pathology in patients with acute respiratory diseases of unknown etiologies. While the complication rate may be acceptable, the procedure should be performed by experienced interventional pulmonologists. However, airway blockers and fluoroscopy are highly recommended when used according to the current guideline. We do not encourage TBLC to be performed without having airway blockers available at the bedside.

Severe COVID-19 with persistent respiratory failure—A retrospective cohort study in a tertiary centre in Malaysia

Introduction

Management of severe COVID-19 patients with persistent respiratory failure after acute phase treatment is not only challenging, but evidence for treatment is scarce, despite some authors reporting favourable clinical responses to corticosteroid therapy in histologically proven secondary organising pneumonia (OP). This study aimed to report the course of the disease, radiological pattern and clinical outcomes of severe COVID-19 patients with persistent respiratory failure.

Methods

This was a retrospective cohort study of severe COVID-19 patients who were admitted to a single tertiary centre from 1 January 2021 to 30 June 2021. The clinical data of the patients during admission and clinic follow-up, including radiological images, were traced using electronic medical records.

Results

In our cohort, the mortality rate for those with severe COVID-19 was 23.1% (173/749). Among the survivors, 46.2% (266/576) had persistent respiratory failure (PRF) after 14 days of illness. Of them, 70.3% (187/266) were followed up, and 68% (128/187) received oral corticosteroid (prednisolone) maintenance treatment. OP pattern made up the majority (81%) of the radiological pattern with a mean severity CT score of 10 (SD±3). The mean prednisolone dose was 0.68mg/kg/day with a mean treatment duration of 47 days (SD±18). About one-third of patients (67/187) had respiratory symptoms at 4 weeks (SD±3). Among 78.1% (146/187) who had a repeated CXR during follow-up, only 12 patients (8.2%, SD±3) had radiological improvement of less than 50% at 6 weeks (SD±3), with 2 of them later diagnosed as pulmonary tuberculosis. Functional assessments, such as the 6-minute walk test and the spirometry, were only performed in 52.4% and 15.5% of the patients, respectively.

Conclusion

Almost half of the patients with severe COVID-19 had PRF, with a predominant radiological OP pattern. More than two-thirds of the PRF patients required prolonged oral corticosteroid treatment. Familiarising clinicians with the disease course, radiological patterns, and potential outcomes of this group of patients may better equip them to manage their patients.

The pathogenesis of coronavirus-19 disease

Severe acute respiratory syndrome-associated coronavirus-2 (SARS-CoV-2) is the causal agent of coronavirus disease-2019 (COVID-19), a systemic illness characterized by variably severe pulmonary symptoms, cardiac conduction abnormalities, diarrhea, and gastrointestinal bleeding, as well as neurologic deficits, renal insufficiency, myalgias, endocrine abnormalities, and other perturbations that reflect widespread microvascular injury and a pro-inflammatory state. The mechanisms underlying the various manifestations of viral infection are incompletely understood but most data suggest that severe COVID-19 results from virus-driven perturbations in the immune system and resultant tissue injury. Aberrant interferon-related responses lead to alterations in cytokine elaboration that deplete resident immune cells while simultaneously recruiting hyperactive macrophages and functionally altered neutrophils, thereby tipping the balance from adaptive immunity to innate immunity. Disproportionate activation of these macrophages and neutrophils further depletes normal activity of B-cells, T-cells, and natural killer (NK) cells. In addition, this pro-inflammatory state stimulates uncontrolled complement activation and development of neutrophil extracellular traps (NETS), both of which promote the coagulation cascade and induce a state of “thrombo-inflammation”. These perturbations have similar manifestations in multiple organ systems, which frequently show pathologic findings related to microvascular injury and thrombosis of large and small vessels. However, the pulmonary findings in patients with severe COVID-19 are generally more pronounced than those of other organs. Not only do they feature inflammatory thromboses and endothelial injury, but much of the parenchymal damage stems from failed maturation of alveolar pneumocytes, interactions between type 2 pneumocytes and non-resident macrophages, and a greater degree of NET formation. The purpose of this review is to discuss the pathogenesis underlying organ damage that can occur in patients with SARS-CoV-2 infection. Understanding these mechanisms of injury is important to development of future therapies for patients with COVID-19, many of which will likely target specific components of the immune system, particularly NET induction, pro-inflammatory cytokines, and subpopulations of immune cells.

Membrane attack complexes, endothelial cell activation, and direct allorecognition

Endothelial cells (ECs) form a critical immune interface regulating both the activation and trafficking of alloreactive T cells. In the setting of solid organ transplantation, donor-derived ECs represent sites where alloreactive T cells encounter major and minor tissue-derived alloantigens. During this initial encounter, ECs may formatively modulate effector responses of these T cells through expression of inflammatory mediators. Direct allorecognition is a process whereby recipient T cells recognize alloantigen in the context of donor EC-derived HLA molecules. Direct alloresponses are strongly modulated by human ECs and are galvanized by EC-derived inflammatory mediators.

Complement are immune proteins that mark damaged or foreign surfaces for immune cell activation. Following labeling by natural IgM during ischemia reperfusion injury (IRI) or IgG during antibody-mediated rejection (ABMR), the complement cascade is terminally activated in the vicinity of donor-derived ECs to locally generate the solid-phase inflammatory mediator, the membrane attack complex (MAC). Via upregulation of leukocyte adhesion molecules, costimulatory molecules, and cytokine trans-presentation, MAC strengthen EC:T cell direct alloresponses and qualitatively shape the alloimmune T cell response. These processes together promote T cell-mediated inflammation during solid organ transplant rejection.

In this review we describe molecular pathways downstream of IgM- and IgG-mediated MAC assembly on ECs in the setting of IRI and ABMR of tissue allografts, respectively. We describe work demonstrating that MAC deposition on ECs generates ‘signaling endosomes’ that sequester and post-translationally enhance the stability of inflammatory signaling molecules to promote EC activation, a process potentiating EC-mediated direct allorecognition. Additionally, with consideration to first-in-human xenotransplantation procedures, we describe clinical therapeutics based on inhibition of the complement pathway. The complement cascade critically mediates EC activation and improved understanding of relevant effector pathways will uncover druggable targets to obviate dysregulated alloimmune T cell infiltration into tissue allografts.

Tissue-specific pathway activities: A retrospective analysis in COVID-19 patients

The ACE2 receptors essential for SARS-CoV-2 infections are expressed not only in the lung but also in many other tissues in the human body. To better understand the disease mechanisms and progression, it is essential to understand how the virus affects and alters molecular pathways in the different affected tissues. In this study, we mapped the proteomics data obtained from Nie X. et al. (2021) to the pathway models of the COVID-19 Disease Map project and WikiPathways. The differences in pathway activities between COVID-19 and non-COVID-19 patients were calculated using the Wilcoxon test. As a result, 46% (5,235) of the detected proteins were found to be present in at least one pathway. Only a few pathways were altered in multiple tissues. As an example, the Kinin-Kallikrein pathway, an important inflammation regulatory pathway, was found to be less active in the lung, spleen, testis, and thyroid. We can confirm previously reported changes in COVID-19 patients such as the change in cholesterol, linolenic acid, and arachidonic acid metabolism, complement, and coagulation pathways in most tissues. Of all the tissues, we found the thyroid to be the organ with the most changed pathways. In this tissue, lipid pathways, energy pathways, and many COVID-19 specific pathways such as RAS and bradykinin pathways, thrombosis, and anticoagulation have altered activities in COVID-19 patients. Concluding, our results highlight the systemic nature of COVID-19 and the effect on other tissues besides the lung.

Potential histopathological and immunological effects of SARS-CoV-2 on the liver

The coronavirus disease outbreak of 2019 (COVID-19) poses a serious threat to public health worldwide. Lung injury is the most common complication of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. However, other organs, including the liver, can also be affected. Currently, there is limited evidence that liver impairment is associated with severe SARS-CoV-2 infection. Clinicians will need to determine whether liver injury is caused by an underlying liver condition, COVID-19 therapy, the virus directly, or immune-mediated inflammation or represents a complicated disease course in the context of COVID-19. To address the scarcity of data on histopathological changes and immunological effects on the liver with COVID-19 positivity, we analyze and summarize recent findings. We searched PubMed, Medline, Google Scholar, Science Direct, Scopus, and Web of Science databases up to December 1, 2021, identifying published studies with the search terms "Histopathology in COVID-19," "COVID-19," "Pathological changes in liver in COVID-19," "Liver pathology in COVID-19," "immunological effects in liver in COVID-19," and "SARS-CoV-2." This concise review will aid clinicians and researchers in better understanding the tissue histopathology and immunological consequences of SARS-CoV-2 on the liver, enabling improved care planning and avoiding future dangers.

Cardiovascular complications of COVID-19 severe acute respiratory syndrome

603,711,760 confirmed cases of COVID-19 have been reported throughout the world and 6,484,136 individuals have died from complications of COVID-19 as of September 7, 2022. Significantly, the Omicron variant has produced the largest number of COVID-19 associated hospitalizations since the beginning of the pandemic. Cardiac injury occurs in ≥20% of the hospitalized patients with COVID-19 and is associated with cardiac dysrhythmias in 17 to 44%, cardiac injury with increases in blood troponin in 22 to 40%, myocarditis in 2 to 7%, heart failure in 4 to 21%, and thromboembolic events in 15 to 39%. Risk factors for cardiac complications include age >70 years, male sex, BMI ≥30 kg/m², diabetes, pre-existing cardiovascular disease, and moderate to severe pneumonia at hospital presentation. Patients with prior cardiovascular disease who contract COVID-19 and experience a significant increase in their blood troponin concentration are at risk for mortality rates as high as 69%. This review focuses on the prevalence, the pathophysiologic mechanisms of CoV-2 injury to the cardiovascular system and the current recommended treatments in hospitalized patients with COVID-19 in order that medical personnel can decrease the morbidity and mortality of patients with COVID-19 and effectively treat patients with Covid and post Covid syndrome.

Study of protease-mediated processes initiating viral infection and cell-cell viral spreading of SARS-CoV-2

Viral-cell entry and cell-cell viral spreading processes of SARS-CoV-2 are subjected to fast evolutionary optimization because of its worldwide spreading, requiring the need for new drug developments. However, this task is still challenging, because a detailed understanding of the underlying molecular processes, mediated by the key cellular proteases TMPRSS2 and furin, is still lacking. Here, we show by large-scale atomistic calculations that binding of the ACE2 cell receptor at one of the heteromers of the SARS-CoV-2 spike leads to a release of its furin cleavage site (S1/S2), enabling an enhanced furin binding, and that this latter process promotes the binding of TMPRSS2 through the release of the TMPRSS2 cleavage site (S2') out of the ACE2-binding heteromer. Moreover, we find that, after proteolytic cleavage, improved furin binding causes that parts of the S2 subunit dissociate from the complex, suggesting that furin promotes the fusion of the S2 subunit with the cell membrane before transfer of the viral RNA. Here we show by computational means that binding of the ACE2-cell receptor at one of the heteromers of the SARS-CoV-2 spike leads to an enhanced binding of the protease furin, promoting the binding of the protease TMPRSS2. Moreover, we show that, after proteolytic cleavage, improved furin binding causes that parts of the heteromer dissociate from the spike.

The state of the art for artificial intelligence in lung digital pathology

Lung diseases carry a significant burden of morbidity and mortality worldwide. The advent of digital pathology (DP) and an increase in computational power have led to the development of artificial intelligence (AI)-based tools that can assist pathologists and pulmonologists in improving clinical workflow and patient management. While previous works have explored the advances in computational approaches for breast, prostate, and head and neck cancers, there has been a growing interest in applying these technologies to lung diseases as well. The application of AI tools on radiology images for better characterization of indeterminate lung nodules, fibrotic lung disease, and lung cancer risk stratification has been well documented. In this article, we discuss methodologies used to build AI tools in lung DP, describing the various hand-crafted and deep learning-based unsupervised feature approaches. Next, we review AI tools across a wide spectrum of lung diseases including cancer, tuberculosis, idiopathic pulmonary fibrosis, and COVID-19. We discuss the utility of novel imaging biomarkers for different types of clinical problems including quantification of biomarkers like PD-L1, lung disease diagnosis, risk stratification, and prediction of response to treatments such as immune checkpoint inhibitors. We also look briefly at some emerging applications of AI tools in lung DP such as multimodal data analysis, 3D pathology, and transplant rejection. Lastly, we discuss the future of DP-based AI tools, describing the challenges with regulatory approval, developing reimbursement models, planning clinical deployment, and addressing AI biases. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Gastrointestinal Ischemia—Stumbling Stone in COVID-19 Patients

The emergence of the novel SARS-CoV2 virus, proclaimed by the World Health Organization (WHO) as a culpable agent for the pandemic situation, caught the scientific and medical communities off guard. One of the most common complications following pulmonary disease is represented by gastrointestinal (GI) disorders, especially ischemic damage. Inflammation, vasculopathy, immobility, endothelial dysfunction, and a hypercoagulable condition have all been proposed as pathophysiological factors for GI ischemia in these patients. Owing to the COVID-19 effect on a variety of GI conditions, especially ischemic changes, and the high mortality rate, physicians should always keep in mind this complication. They should take a deeper look at clinical and imaging modalities in this cohort of patients so that a proper and time-saving treatment strategy can be applied. Our study aimed to elucidate the thrombogenic mechanism in different GI disorders. Moreover, we analyzed the factors related to necrotic GI changes, by summarizing the already reported data of GI ischemia in COVID-19. To the best of our knowledge, this review is the first to incorporate all GI ischemia cases reported in the literature so far.

COVID-19 on Chest CT: Translating Known Microscopic Findings to Imaging Observations

Purpose: To describe the imaging findings of COVID-19 and correlate them with their known pathology observations. Methods: This is an IRB-approved retrospective study performed at Columbia University Irving Medical Center (IRB # AAAS9652) that included symptomatic adult patients (21 years or older) who presented to our emergency room and tested positive for COVID-19 and were either admitted or discharged with at least one chest CT from 11 March 2020 through 1 July 2020. CT scans were ordered by the physicians caring for the patients; our COVID-19 care protocols did not specify the timing for chest CT scans. A scoring system was used to document the extent of pulmonary involvement. The total CT grade was the sum of the individual lobar grades and ranged from 0 (no involvement) to 16 (maximum involvement). The distribution of lung abnormalities was described as peripheral (involving the outer one-third of the lung), central (inner two-thirds of the lung), or both. Additional CT findings, including the presence of pleural fluid, atelectasis, fibrosis, cysts, and pneumothorax, were recorded. Contrast-enhanced CT scans were evaluated for the presence of a pulmonary embolism, while non-contrast chest CT scans were evaluated for hyperdense vessels. Results: 209 patients with 232 CT scans met the inclusion criteria. The average age was 61 years (range 23–97 years), and 56% of the patients were male. The average score reflecting the extent of the disease on the CT was 10.2 (out of a potential grade of 16). Further, 73% of the patients received contrast, which allowed the identification of a pulmonary embolism in 21%. Of those without contrast, 33% had hyperdense vessels, which might suggest a chronic pulmonary embolism. Further, 47% had peripheral opacities and 9% had a Hampton’s hump, and 78% of the patients had central consolidation, while 28% had round consolidations. Atelectasis was, overall, infrequent at 5%. Fibrosis was observed in 11% of those studied, with 6% having cysts and 3% pneumothorax. Conclusions: The CT manifestations of COVID-19 can be divided into findings related to endothelial and epithelial injury, as were seen on prior post-mortem reports. Endothelial injury may benefit from treatments to stabilize the endothelium. Epithelial injury is more prone to developing pulmonary fibrotic changes.

Comprehensive Analysis of Disease Pathology in Immunocompetent and Immunocompromised Hosts following Pulmonary SARS-CoV-2 Infection

The Coronavirus disease 2019 (COVID-19) pandemic disproportionately affects immunocompetent and immunocompromised individuals, with the latter group being more vulnerable to severe disease and death. However, the differential pathogenesis of SARS-CoV-2 in the context of a specific immunological niche remains unknown. Similarly, systematic analysis of disease pathology in various extrapulmonary organs in immunocompetent and immunocompromised hosts during SARS-CoV-2 infection is not fully understood. We used a hamster model of SARS-CoV-2 infection, which recapitulates the pathophysiology of patients with mild-to-moderate COVID-19, to determine the dynamics of SARS-CoV-2 replication and histopathology at organ-level niches and map how COVID-19 symptoms vary in different immune contexts. Hamsters were intranasally infected with low (LD) or high (HD) inoculums of SARS-CoV-2, and the kinetics of disease pathology and viral load in multiple organs, antibody response, inflammatory cytokine expression, and genome-wide lung transcriptome by RNAseq analysis were determined and compared against corresponding responses from chemically induced immunocompromised hamsters. We observed transient body weight loss proportional to the SARS-CoV-2 infectious dose in immunocompetent hamsters. The kinetics of viral replication and peak viral loads were similar between LD and HD groups, although the latter developed more severe disease pathology in organs. Both groups generated a robust serum antibody response. In contrast, infected immunocompromised animals showed more prolonged body weight loss and mounted an inadequate SARS-CoV-2-neutralizing antibody response. The live virus was detected in the pulmonary and extrapulmonary organs for extended periods. These hamsters also had persistent inflammation with severe bronchiolar-alveolar hyperplasia/metaplasia. Consistent with the differential disease presentation, distinct changes in inflammation and immune cell response pathways and network gene expression were seen in the lungs of SARS-CoV-2-infected immunocompetent and immunocompromised animals.

Autopsy findings in COVID-19 infection-related death: a systematic review

Introduction

Coronavirus-19 disease (COVID-19) has been declared as pandemic by the World Health Organization (WHO) in March 2020. As of 28 November 2021, there were more than 260 million cases and nearly 5.2 million deaths caused by COVID-19. The most affected system by COVID-19 infection was the respiratory system although several other studies suggested multi-organ involvement with pathophysiology that was not clearly understood. Autopsy findings were beneficial to researchers to determine the mechanism behind these organ failures. The objective of this review was to summarize the autopsy findings related to COVID-19 death.

Method

Online literature search was conducted via online databases such as Scopus, PubMed and Google Scholar. The keywords inputted during the search were “post-mortem”, “autopsy” and “COVID-19” in title, abstract and keywords. The inclusion criteria were the topic related with the title of this review, published in 2020–2021, have full text available and in English language. Any articles that were not related, duplicated studies, review articles including systematic review and meta-analysis and in other languages were excluded.

Results

A total of 20 articles were included in this review. The articles reviewed were mostly case reports and case series while others were case-control and cohort study ranging from one to 348 cases. Majority were originated from the United States of America (USA).

Conclusion

The most frequent system described in autopsy findings in COVID-19 death was the respiratory system, with the most common histological finding of diffuse alveolar damage (DAD). Majority of the findings of other organs were related to chronic diseases.

Molecular, Viral and Clinical Features of Alcohol- and Non-Alcohol-Induced Liver Injury

Hepatic cells are sensitive to internal and external signals. Ethanol is one of the oldest and most widely used drugs in the world. The focus on the mechanistic engine of the alcohol-induced injury has been in the liver, which is responsible for the pathways of alcohol metabolism. Ethanol undergoes a phase I type of reaction, mainly catalyzed by the cytoplasmic enzyme, alcohol dehydrogenase (ADH), and by the microsomal ethanol-oxidizing system (MEOS). Reactive oxygen species (ROS) generated by cytochrome (CYP) 2E1 activity and MEOS contribute to ethanol-induced toxicity. We aimed to: (1) Describe the cellular, pathophysiological and clinical effects of alcohol misuse on the liver; (2) Select the biomarkers and analytical methods utilized by the clinical laboratory to assess alcohol exposure; (3) Provide therapeutic ideas to prevent/reduce alcohol-induced liver injury; (4) Provide up-to-date knowledge regarding the Corona virus and its affect on the liver; (5) Link rare diseases with alcohol consumption. The current review contributes to risk identification of patients with alcoholic, as well as non-alcoholic, liver disease and metabolic syndrome. Additional prevalence of ethnic, genetic, and viral vulnerabilities are presented.

Clinical, Virological, and Pathological Profile of Patients Who Died of COVID-19: An Autopsy-Based Study From India

Background and objective Ever since its emergence in December 2019, coronavirus disease 2019 (COVID-19) has affected more than 220 million people worldwide, resulting in more than 45 million deaths. The present autopsy-based study was undertaken to understand the pathophysiology of the disease and correlate the histopathological and virological findings with the antemortem clinical and biochemical determinants. Methods In this prospective observational study, autopsies were carried out on 21 reverse transcription-polymerase chain reaction (RT-PCR)-proven COVID-19 patients who had died of the disease. The histopathological findings of tissue samples from lungs, liver, and kidneys collected during the autopsy were graded based on their presence or absence; if present, they were graded as either focal or diffuse. The findings were correlated with antemortem clinical and biochemical findings. Postmortem tissue RT-PCR analysis was conducted, and findings were compared with postmortem histopathological findings. Results There was multisystem involvement with the COVID-19 cases. The involvement of lungs was observed in most of the cases (90.4%). The presence of viral RNA was observed in all the organs including the liver (57.1%) and kidney (66.6%). An association was observed between antemortem biochemical parameters [aspartate aminotransferase (AST), alanine aminotransferase (ALT)] and the histopathological features in the liver. No correlation between the Sequential Organ Failure Assessment (SOFA) score recorded clinically and lung histopathology was observed; nor was there any correlation between blood urea-creatinine levels and kidney histopathology. Conclusions Our study shows that COVID-19 is a multisystemic disease and the mortality associated with it is likely to be multifactorial. Despite the presence of amplifiable severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in various organs, no association could be established between the clinical and histopathology findings. Neither the duration of hospitalization nor the duration of mechanical ventilation showed any correlation with the severity of histopathological findings in the lungs at autopsy.

Pulmonary hematoidin deposition in a case of severe COVID19 pneumonia

A 59-year-old male with past medical history significant for hypertension, coronary artery disease, atrial fibrillation, hyperlipidemia, obesity, obstructive sleep apnea and deep vein thrombosis developed severe COVID19 pneumonia. His clinical course was noted for progressive respiratory failure that subsequently resulted in bilateral lung transplantation. Examination of the explanted lungs was notable for the presence of extensive grossly apparent bright yellow discolorations that histologically represented hematoidin deposits. The background lung was affected by diffuse alveolar damage, accompanied by infarcts and organizing thrombi. This case suggests that a combination of acute lung injury and thrombotic complications in severe COVID19 pneumonia can facilitate formation of pockets of anoxic environment leading to hematoidin deposition within lung tissue.

COVID-19 Survival and its impact on chronic kidney disease

Up to 87% of patients hospitalized with coronavirus disease 2019 (COVID-19) experience chronic sequelae following infection. The long-term impact of COVID-19 infection on kidney function is largely unknown at this point in the COVID-19 pandemic. In this review, we highlight the current understanding of the pathophysiology of COVID-19-associated kidney injury and the impact COVID-19 may have on long-term kidney function. COVID-19-induced acute kidney injury may lead to tubular injury, endothelial injury, and glomerular injury. We highlight histopathologic correlates from large kidney biopsy and autopsy series. By conducting a comprehensive review of published literature to date, we summarize the rates of recovery from COVID-19-associated-AKI. Finally, we discuss how certain genetic differences, including APOL1 risk alleles (a risk factor for collapsing glomerulopathy), coupled with systemic healthcare disparities, may lead to a disproportionate burden of post-COVID-19-kidney function decline among racial and ethnic minority groups. We highlight the need for prospective studies to determine the true incidence of chronic kidney disease burden after COVID-19.

Spectrum of Kidney Injury Following COVID-19 Disease: Renal Biopsy Findings in a Single Italian Pathology Service

The onset of coronavirus disease (COVID-19) as a pandemic infection, has led to increasing insights on its pathophysiology and clinical features being revealed, such as a noticeable kidney involvement. In this study, we describe the histopathological, immunofluorescence, and ultrastructural features of biopsy-proven kidney injury observed in a series of SARS-CoV-2 positive cases in our institution from April 2020 to November 2021. We retrieved and retrospectively reviewed nine cases (two pediatric and seven adults) that experienced nephrotic syndrome (six cases), acute kidney injury (two cases), and a clinically silent microhematuria and leukocyturia. Kidney biopsies were investigated by means of light microscopy, direct immunofluorescence, and electron microscopy. The primary diagnoses were minimal change disease (four cases), acute tubular necrosis (two cases), collapsing glomerulopathy (two cases), and C3 glomerulopathy (one case). None of the cases showed viral or viral-like particles on ultrastructural analysis. Novel and specific histologic features on kidney biopsy related to SARS-CoV-2 infection have been gradually disclosed and reported, harboring relevant clinical and therapeutic implications. Recognizing and properly diagnosing renal involvement in patients experiencing COVID-19 could be challenging (due to the lack of direct proof of viral infection, e.g., viral particles) and requires a proper integration of clinical and pathological data.

Prophylactic versus therapeutic dose anticoagulation effects on survival among critically ill patients with COVID-19

INTRODUCTION

Although patients with severe COVID-19 are known to be at high risk of developing thrombotic events, the effects of anticoagulation (AC) dose and duration on in-hospital mortality in critically ill patients remain poorly understood and controversial. The goal of this study was to investigate survival of critically ill COVID-19 patients who received prophylactic or therapeutic dose AC and analyze the mortality rate with respect to detailed demographic and clinical characteristics.

MATERIALS AND METHODS

We conducted a retrospective, observational study of critically ill COVID-19 patients admitted to the ICU at Stony Brook University Hospital in New York who received either prophylactic (n = 158) or therapeutic dose AC (n = 153). Primary outcome was in-hospital death assessed by survival analysis and covariate-adjusted Cox proportional hazard model.

RESULTS

For the first 3 weeks of ICU stay, we observed similar survival curves for prophylactic and therapeutic AC groups. However, after 3 or more weeks of ICU stay, the therapeutic AC group, characterized by high incidence of acute kidney injury (AKI), had markedly higher death incidence rates with 8.6 deaths (95% CI = 6.2-11.9 deaths) per 1,000 person-days and about 5 times higher risk of death (adj. HR = 4.89, 95% CI = 1.71-14.0, p = 0.003) than the prophylactic group (2.4 deaths [95% CI = 0.9-6.3 deaths] per 1,000 person-days). Among therapeutic AC users with prolonged ICU admission, non-survivors were characterized by older males with depressed lymphocyte counts and cardiovascular disease.

CONCLUSIONS

Our findings raise the possibility that prolonged use of high dose AC, independent of thrombotic events or clinical background, might be associated with higher risk of in-hospital mortality. Moreover, AKI, age, lymphocyte count, and cardiovascular disease may represent important risk factors that could help identify at-risk patients who require long-term hospitalization with therapeutic dose AC treatment.

Postmortem CT in decedents with SARS-CoV-2 infection. A single institution experience

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 produced a global pandemic with significant mortality. As autopsies are not routinely performed on all decedents with SARS-CoV-2 infection, postmortem CT (PMCT) may be valuable to provide additional information on the cause of death and risk factors known to be associated with an increased mortality in COVID-19. The purpose of this manuscript is to review the PMCT findings in a series of 42 decedents with SARS-CoV-2 infection from our institution. Retrospective analysis of 42 decedents who had a positive postmortem nasopharyngeal swab for SARS-CoV-2 and had a PMCT were included in this study. Images were reviewed for pulmonary findings seen in COVID-19 and other organ involvement. Of the 42 decedents, although the majority had imaging findings in the lungs that would be consistent with COVID-19 and acute respiratory distress syndrome, in 14% of the decedents the SARS-CoV-2 infection was likely coincidental and the PMCT findings suggested that they died from other pathology. Over half of the decedents that died from COVID-19 had PMCT findings of vascular disease. PMCT is useful to identify pulmonary and extra pulmonary findings in decedents with SARS-CoV-2 infection that can provide additional information, which may be useful for the forensic pathologist to help determine the underlying cause of death.

Supplemental data for this article are available online at

Right ventricular dysfunction and pulmonary hypertension in COVID-19: a meta-analysis of prevalence and its association with clinical outcome

INTRODUCTION

Rapid spread of COVID-19 has caused detrimental effects globally. Involvement of the ACE2 receptor has identified COVID-19 as a multi-organ disease. Preliminary studies have provided evidence that cardiac involvement, including right ventricular dysfunction (RVD) and pulmonary hypertension (PH), were found in COVID-19 cases, even in the non-advanced stage. This meta-analysis aims to analyze the prevalence of RVD and PH, and their association with COVID-19 clinical outcome.

MATERIAL AND METHODS

A systematic data search was conducted through PubMed, medRxiv, ProQuest, Science Direct, and Scopus databases using constructed keywords based on MeSH terms. Any outcomes regarding mortality, severity, ICU admission, and mechanical ventilation usage were analyzed using RevMan v.5.4 and Stata v.16.

RESULTS

A total of 16 eligible studies (1,728 patients) were included. Pooled prevalence of RVD in COVID-19 was 19% (95% CI: 13-25%), and PH was 22% (95% CI: 14-31%). RVD was associated with increased mortality (OR = 2.98 (95% CI: 1.50-5.89), p = 0.002), severity (OR = 3.61 (95% CI: 2.05-6.35), p < 0.001), ICU admission (OR = 1.70 (95% CI: 1.12-2.56), p = 0.01), and mechanical ventilation (MV) usage (OR = 1.60 (95% CI: 1.14-2.25), p = 0.007). PH was also associated with increased mortality (OR = 5.42 (95% CI: 2.66-11.060, p < 0.001), severity (OR = 5.74 (95% CI: 2.28-14.49), p < 0.001), and ICU admission (OR = 12.83 (95% CI: 3.55-46.41), p < 0.001).

CONCLUSIONS

RVD and PH were prevalent in COVID-19 and associated with mortality, severity, ICU admission, and MV usage in COVID-19 patients. Bedside echocardiography examination could be considered as a novel risk stratification tool in COVID-19.

Acute lung injury-from cannabis to COVID

Recent world events have refocused attention on the pathology associated with clinical acute respiratory distress syndrome (ARDS). The vast majority of cases of clinical ARDS will have diffuse alveolar damage (DAD) histologically, but other histologies may occur less frequently. The aim of this paper is to provide a review of the pathology of DAD and acute fibrinous and organizing pneumonia and provide insights into the pathologic features associated with the E-cigarette/vaping-associated lung-injury outbreak and the ongoing SARS-CoV-2 pandemic.

Recovering from a pandemic: pulmonary fibrosis after SARS-CoV-2 infection

Acute manifestations of SARS-CoV-2 infection continue to impact the lives of many across the world. Post-acute sequelae of coronavirus disease 2019 (COVID-19) may affect 10–30% of survivors of COVID-19, and post-acute sequelae of COVID-19 (PASC)-pulmonary fibrosis is a long-term outcome associated with major morbidity. Data from prior coronavirus outbreaks (severe acute respiratory syndrome and Middle East respiratory syndrome) suggest that pulmonary fibrosis will contribute to long-term respiratory morbidity, suggesting that PASC-pulmonary fibrosis should be thoroughly screened for through pulmonary function testing and cross-sectional imaging. As data accumulates on the unique pathobiologic mechanisms underlying critical COVID-19, a focus on corollaries to the subacute and chronic profibrotic phenotype must be sought as well. Key aspects of acute COVID-19 pathobiology that may account for increased rates of pulmonary fibrosis include monocyte/macrophage–T-cell circuits, profibrotic RNA transcriptomics, protracted elevated levels of inflammatory cytokines, and duration of illness and ventilation. Mechanistic understanding of PASC-pulmonary fibrosis will be central in determining therapeutic options and will ultimately play a role in transplant considerations. Well-designed cohort studies and prospective clinical registries are needed. Clinicians, researchers and healthcare systems must actively address this complication of PASC to minimise disability, maximise quality of life and confront a post-COVID-19 global health crisis.

A complication of COVID-19, PASC-pulmonary fibrosis, has the potential to become a global respiratory health crisis. Dedicated surveillance, mechanistic understanding and clinical and research efforts are needed to confront this emerging sequela of COVID-19.https://bit.ly/3GEyB04

Histologic pulmonary lesions of SARS-CoV-2 in 4 nonhuman primate species: An institutional comparative review

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an emergent, amphixenotic infection that resulted in a pandemic declaration in March 2020. A rapid search for appropriate animal models of this newly emergent viral respiratory disease focused initially on traditional nonhuman primate research species. Nonhuman primate models have previously been shown to be valuable in evaluation of emerging respiratory coronaviruses with pandemic potential (ie, SARS-CoV and Middle East respiratory syndrome coronavirus). In this article, we review the pulmonary histopathologic characteristics and immunohistochemical evaluation of experimental SARS-CoV-2 infection in the rhesus macaque, pigtail macaque, African green monkey, and squirrel monkey. Our results indicate that all evaluated nonhuman primate species developed variably severe histopathologic changes typical of coronavirus respiratory disease characterized by interstitial pneumonia with or without syncytial cell formation, alveolar fibrin, and pulmonary edema that progressed to type II pneumocyte hyperplasia. Lesion distribution was multifocal, frequently subpleural, and often more severe in lower lung lobes. However, squirrel monkeys showed the least severe and least consistent lesions of the evaluated nonhuman primates. Additionally, our results highlight the disparate physical relationship between viral antigen and foci of pulmonary lesions. While classic respiratory coronaviral lesions were observed in the lungs of all nonhuman primates evaluated, none of the primates exhibited severe lesions or evidence of diffuse alveolar damage and therefore are unlikely to represent the severe form of SARS-CoV-2 infection observed in fatal human cases.

Pulmonary Hypertensive Changes Secondary to COVID-19 Pneumonia in a Chronically SARS-CoV-2-Infected Bilateral Lung Explant

COVID-19, the syndrome caused by the novel coronavirus SARS-CoV-2, has spread throughout the world, causing the death of at least three million people. For the over 81 million who have recovered, however, the long-term effects are only beginning to manifest. We performed a bilateral lung transplant on a 31-year-old male patient for chronic hypoxic respiratory failure, severe pulmonary hypertension and radiographically identified pulmonary fibrosis five months after an acute COVID-19 infection. The explant demonstrated moderate pulmonary vascular remodeling with intimal thickening and medial hypertrophy throughout, consistent with pulmonary hypertension. The parenchyma demonstrated an organizing lung injury in the proliferative phase, with severe fibrosis, histiocytic proliferation, type II pneumocyte hyperplasia, and alveolar loss consistent with known COVID-19 pneumonia complications.

This report highlights a novel histologic finding in severe, chronic COVID-19. Although the findings in acute COVID-19 pneumonia have been well-examined at autopsy, the chronic course of this complex disease is not yet understood. The case presented herein suggests that COVID-induced pulmonary hypertension may become more common as more patients survive severe SARS-CoV-2-related pneumonia. Pulmonologists and pulmonary pathologists should be aware of this possible association and look for the clinical, radiographic, and histologic criteria in the appropriate clinical setting.

Myocardial Perfusion Imaging After Severe COVID-19 Infection Demonstrates Regional Ischemia Rather Than Global Blood Flow Reduction

Background: Acute myocardial damage is common in severe COVID-19. Post-mortem studies have implicated microvascular thrombosis, with cardiovascular magnetic resonance (CMR) demonstrating a high prevalence of myocardial infarction and myocarditis-like scar. The microcirculatory sequelae are incompletely characterized. Perfusion CMR can quantify the stress myocardial blood flow (MBF) and identify its association with infarction and myocarditis. Objectives: To determine the impact of the severe hospitalized COVID-19 on global and regional myocardial perfusion in recovered patients. Methods: A case-control study of previously hospitalized, troponin-positive COVID-19 patients was undertaken. The results were compared with a propensity-matched, pre-COVID chest pain cohort (referred for clinical CMR; angiography subsequently demonstrating unobstructed coronary arteries) and 27 healthy volunteers (HV). The analysis used visual assessment for the regional perfusion defects and AI-based segmentation to derive the global and regional stress and rest MBF. Results: Ninety recovered post-COVID patients {median age 64 [interquartile range (IQR) 54-71] years, 83% male, 44% requiring the intensive care unit (ICU)} underwent adenosine-stress perfusion CMR at a median of 61 (IQR 29-146) days post-discharge. The mean left ventricular ejection fraction (LVEF) was 67 ± 10%; 10 (11%) with impaired LVEF. Fifty patients (56%) had late gadolinium enhancement (LGE); 15 (17%) had infarct-pattern, 31 (34%) had non-ischemic, and 4 (4.4%) had mixed pattern LGE. Thirty-two patients (36%) had adenosine-induced regional perfusion defects, 26 out of 32 with at least one segment without prior infarction. The global stress MBF in post-COVID patients was similar to the age-, sex- and co-morbidities of the matched controls (2.53 ± 0.77 vs. 2.52 ± 0.79 ml/g/min, p = 0.10), though lower than HV (3.00 ± 0.76 ml/g/min, p< 0.01). Conclusions: After severe hospitalized COVID-19 infection, patients who attended clinical ischemia testing had little evidence of significant microvascular disease at 2 months post-discharge. The high prevalence of regional inducible ischemia and/or infarction (nearly 40%) may suggest that occult coronary disease is an important putative mechanism for troponin elevation in this cohort. This should be considered hypothesis-generating for future studies which combine ischemia and anatomical assessment.

The liver in COVID-19: prevalence, patterns, predictors, and impact on outcomes of liver test abnormalities

BACKGROUND

Coronavirus disease 2019 (COVID-19) has caused a global pandemic unprecedented in over a century, with ≈35 million cases, and more than 1 million deaths globally. Though predominantly a lower respiratory illness, other organ injuries are well-recognized. Among these, liver injury is of major interest.

OBJECTIVE

To define prevalence, pattern, predictors, and impact of liver injury among patients hospitalized with COVID-19.

METHODS

Demographic, clinical, and biochemical data were collected retrospectively among patients admitted to St. Luke's University Hospital with COVID-19 between 1 March and 18 April 2020. Association of liver tests (LTs) with mortality and need for mechanical ventilation, adjusted for demographic, clinical and biochemical predictors, was examined.

RESULTS

Data were available on 551 patients. Prevalence of any or ≥3 × upper limit of normal transaminase elevation on was 61.2 and 9.4% on admission, and 72.1 and 22.4% at peak. Bilirubin and alkaline phosphatase elevations were less common on admission (11.4 and 12.6%, respectively), and at peak (17.7 and 22%, respectively). All liver test (LT) elevations were consistently predicted by inflammatory markers. Hyperbilirubinemia predicted mortality on admission and at peak. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) had opposite impact on mortality with AST positively, and ALT negatively associated with mortality. Hence, besides hyperbilirubinemia, AST:ALT ratio emerged as the best marker for mortality among the LTs.

CONCLUSION

LT elevations among patients presenting with COVID-19 are very common, though majority are mild. Admission and peak bilirubin ≥1 mg/dl, as well as admission and peak AST:ALT ratio were significant predictors of mortality, along with age, myocardial injury, and chronic medical illness.

COVID-19 Mechanisms in the Human Body-What We Know So Far

More than one and a half years have elapsed since the commencement of the coronavirus disease 2019 (COVID-19) pandemic, and the world is struggling to contain it. Being caused by a previously unknown virus, in the initial period, there had been an extreme paucity of knowledge about the disease mechanisms, which hampered preventive and therapeutic measures against COVID-19. In an endeavor to understand the pathogenic mechanisms, extensive experimental studies have been conducted across the globe involving cell culture-based experiments, human tissue organoids, and animal models, targeted to various aspects of the disease, viz., viral properties, tissue tropism and organ-specific pathogenesis, involvement of physiological systems, and the human immune response against the infection. The vastly accumulated scientific knowledge on all aspects of COVID-19 has currently changed the scenario from great despair to hope. Even though spectacular progress has been made in all of these aspects, multiple knowledge gaps are remaining that need to be addressed in future studies. Moreover, multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have emerged across the globe since the onset of the first COVID-19 wave, with seemingly greater transmissibility/virulence and immune escape capabilities than the wild-type strain. In this review, we narrate the progress made since the commencement of the pandemic regarding the knowledge on COVID-19 mechanisms in the human body, including virus-host interactions, pulmonary and other systemic manifestations, immunological dysregulations, complications, host-specific vulnerability, and long-term health consequences in the survivors. Additionally, we provide a brief review of the current evidence explaining molecular mechanisms imparting greater transmissibility and virulence and immune escape capabilities to the emerging SARS-CoV-2 variants.

Mechanisms of immunothrombosis in COVID-19

PURPOSE OF REVIEW

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus-2. Over the past year, COVID-19 has posed a significant threat to global health. Although the infection is associated with mild symptoms in many patients, a significant proportion of patients develop a prothrombotic state due to a combination of alterations in coagulation and immune cell function. The purpose of this review is to discuss the pathophysiological characteristics of COVID-19 that contribute to the immunothrombosis.

RECENT FINDINGS

Endotheliopathy during COVID-19 results in increased multimeric von Willebrand factor release and the potential for increased platelet adhesion to the endothelium. In addition, decreased anticoagulant proteins on the surface of endothelial cells further alters the hemostatic balance. Soluble coagulation markers are also markedly dysregulated, including plasminogen activator inhibitor-1 and tissue factor, leading to COVID-19 induced coagulopathy. Platelet hyperreactivity results in increased platelet-neutrophil and -monocyte aggregates further exacerbating the coagulopathy observed during COVID-19. Finally, the COVID-19-induced cytokine storm primes neutrophils to release neutrophil extracellular traps, which trap platelets and prothrombotic proteins contributing to pulmonary thrombotic complications.

SUMMARY

Immunothrombosis significantly contributes to the pathophysiology of COVID-19. Understanding the mechanisms behind COVID-19-induced coagulopathy will lead to future therapies for patients.