Lung Autopsy Research Articles

The purinergic receptor P2X7 and the NLRP3 inflammasome are druggable host factors required for SARS-CoV-2 infection.

Purinergic receptors and NOD-like receptor protein 3 (NLRP3) inflammasome regulate inflammation and viral infection, but their effects on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remain poorly understood. Here, we report that the purinergic receptor P2X7 and NLRP3 inflammasome are cellular host factors required for SARS-CoV-2 infection. Lung autopsies from patients with severe coronavirus disease 2019 (COVID-19) reveal that NLRP3 expression is increased in host cellular targets of SARS-CoV-2 including alveolar macrophages, type II pneumocytes and syncytia arising from the fusion of infected macrophages, thus suggesting a potential role of NLRP3 and associated signaling pathways to both inflammation and viral replication. In vitro studies demonstrate that NLRP3-dependent inflammasome activation is detected upon macrophage abortive infection. More importantly, a weak activation of NLRP3 inflammasome is also detected during the early steps of SARS-CoV-2 infection of epithelial cells and promotes the viral replication in these cells. Interestingly, the purinergic receptor P2X7, which is known to control NLRP3 inflammasome activation, also favors the replication of D614G and alpha SARS-CoV-2 variants. Altogether, our results reveal an unexpected relationship between the purinergic receptor P2X7, the NLRP3 inflammasome and the permissiveness to SARS-CoV-2 infection that offers novel opportunities for COVID-19 treatment.

Altered sphingolipid pathway in SARS-CoV-2 infected human lung tissue.

The SARS-CoV-2 mediated COVID-19 pandemic has impacted millions worldwide. Hyper-inflammatory processes, including cytokine storm, contribute to long-standing tissue injury and damage in COVID-19. The metabolism of sphingolipids as regulators of cell survival, differentiation, and proliferation has been implicated in inflammatory signaling and cytokine responses. Sphingosine-kinase-1 (SK1) and ceramide-synthase-2 (CERS2) generate metabolites that regulate the anti- and pro-apoptotic processes, respectively. Alterations in SK1 and CERS2 expression may contribute to the inflammation and tissue damage during COVID-19. The central objective of this study is to evaluate structural changes in the lung post-SARS-CoV-2 infection and to investigate whether the sphingolipid rheostat is altered in response to SARS-CoV-2 infection. Central and peripheral lung tissues from COVID-19+ or control autopsies and resected lung tissue from COVID-19 convalescents were subjected to histologic evaluation of airspace and collagen deposisiton, and immunohistochemical evaluation of SK1 and CERS2. Here, we report significant reduction in air space and increase in collagen deposition in lung autopsy tissues from patients who died from COVID-19 (COVID-19+) and COVID-19 convalescent individuals. SK1 expression increased in the lungs of COVID-19+ autopsies and COVID-19 convalescent lung tissue compared to controls and was mostly associated with Type II pneumocytes and alveolar macrophages. No significant difference in CERS2 expression was noted. SARS-CoV-2 infection upregulates SK1 and increases the ratio of SK1 to CERS2 expression in lung tissues of COVID-19 autopsies and COVID-19 convalescents. These data suggest an alteration in the sphingolipid rheostat in lung tissue during COVID-19, suggesting a potential contribution to the inflammation and tissue damage associated with viral infection.

The Role of Toll-like Receptor-4 in Macrophage Imbalance in Lethal COVID-19 Lung Disease, and Its Correlation with Galectin-3.

To the current data, there have been 6,955,141 COVID-19-related deaths worldwide, reported to WHO. Toll-like receptors (TLRs) implicated in bacterial and virus sensing could be a crosstalk between activation of persistent innate-immune inflammation, and macrophage's sub-population alterations, implicated in cytokine storm, macrophage over-activation syndrome, unresolved Acute Respiratory Disease Syndrome (ARDS), and death. The aim of this study is to demonstrate the association between Toll-like-receptor-4 (TLR-4)-induced inflammation and macrophage imbalance in the lung inflammatory infiltrate of lethal COVID-19 disease. Twenty-five cases of autopsy lung tissues were studied by digital pathology-based immunohistochemistry to evaluate expression levels of TLR-4 (CD 284), pan-macrophage marker CD68 (clone KP1), sub-population marker related to alveolar macrophage Galectin-3 (GAL-3) (clone 9C4), and myeloid derived CD163 (clone MRQ-26), respectively. SARS-CoV-2 viral persistence has been evaluated by in situ hybridation (ISH) method. This study showed TLR-4 up-regulation in a subgroup of patients, increased macrophage infiltration in both Spike-1(+) and Spike-1(-) lungs (p < 0.0001), and a macrophage shift with important down-regulation of GAL-3(+) alveolar macrophages associated with Spike-1 persistence (p < 0.05), in favor of CD163(+) myeloid derived monocyte-macrophages. Data show that TLR-4 expression induces a persistent activation of the inflammation, with inefficient resolution, and pathological macrophage shift, thus explaining one of the mechanisms of lethal COVID-19.

Effectiveness of Immature Asian Pear Extract on Pulmonary Injury Caused by Particulate Matter in Mice

The use of natural products in developing respiratory-function-protective pharmaceuticals is actively progressing. However, in this context, the improvement effects of young Asian pear (Pyrus pyrifolia Nakai) extracts have not been evaluated yet. Thus, this study investigated the anti-inflammatory and lung damage improvement effects of immature Asian pear extract (IAP; 400, 200, and 100 mg/kg) using a particulate matter 2.5 μm (PM2.5)-induced sub-acute lung injury mouse model. The experimental results were compared with dexamethasone (0.75 mg/kg), used as a control drug. After two intranasal instillations of PM2.5 and ten doses of IAP extract for eight days, changes in macroscopic lung autopsy, leukocyte fractionation from bronchoalveolar lavage fluid, lung antioxidant defense system, lung histopathology, and mRNA expression in lung tissue were confirmed. Stress-induced inflammatory lung damage through the increased expression of PM2.5-induced PI3K/Akt and p38 MAPK mRNA was significantly suppressed via the administration of IAP extract (400–100 mg/kg). Furthermore, IAP extract administration promoted serous fluid production in lung tissue, increased substance P and ACh levels, and decreased mucus-production-related expression of MUC5AC and MUC5B mRNA. Interestingly, the observed effects showed a dose-dependent manner without serious hepatotoxicity. The results of this study indicate that a proper oral administration of IAP extract could be helpful in protecting against lung diseases, positioning IAP extract as a potential candidate for an alternative agent to safeguard the respiratory system.

Endothelial FoxM1 reactivates aging-impaired endothelial regeneration for vascular repair and resolution of inflammatory lung injury.

Aging is a major risk factor of high incidence and increased mortality of acute respiratory distress syndrome (ARDS). Here, we demonstrated that persistent lung injury and high mortality in aged mice after sepsis challenge were attributable to impaired endothelial regeneration and vascular repair. Genetic lineage tracing study showed that endothelial regeneration after sepsis-induced vascular injury was mediated by lung resident endothelial proliferation in young adult mice, whereas this intrinsic regenerative program was impaired in aged mice. Expression of forkhead box M1 (FoxM1), an important mediator of endothelial regeneration in young mice, was not induced in lungs of aged mice. Transgenic FOXM1 expression or in vivo endothelium-targeted nanoparticle delivery of the FOXM1 gene driven by an endothelial cell (EC)-specific promoter reactivated endothelial regeneration, normalized vascular repair and resolution of inflammation, and promoted survival in aged mice after sepsis challenge. In addition, treatment with the FDA-approved DNA demethylating agent decitabine was sufficient to reactivate FoxM1-dependent endothelial regeneration in aged mice, reverse aging-impaired resolution of inflammatory injury, and promote survival. Mechanistically, aging-induced Foxm1 promoter hypermethylation in mice, which could be inhibited by decitabine treatment, inhibited Foxm1 induction after sepsis challenge. In COVID-19 lung autopsy samples, FOXM1 was not induced in vascular ECs of elderly patients in their 80s, in contrast with middle-aged patients (aged 50 to 60 years). Thus, reactivation of FoxM1-mediated endothelial regeneration and vascular repair may represent a potential therapy for elderly patients with ARDS.

Meta-analysis of Transcriptomic Data from Lung Autopsy and Cellular Models of SARS-CoV-2 Infection.

Severe COVID-19 is a systemic disorder involving excessive inflammatory response, metabolic dysfunction, multi-organ damage, and several clinical features. Here, we performed a transcriptome meta-analysis investigating genes and molecular mechanisms related to COVID-19 severity and outcomes. First, transcriptomic data of cellular models of SARS-CoV-2 infection were compiled to understand the first response to the infection. Then, transcriptomic data from lung autopsies of patients deceased due to COVID-19 were compiled to analyze altered genes of damaged lung tissue. These analyses were followed by functional enrichment analyses and gene-phenotype association. A biological network was constructed using the disturbed genes in the lung autopsy meta-analysis. Central genes were defined considering closeness and betweenness centrality degrees. A sub-network phenotype-gene interaction analysis was performed. The meta-analysis of cellular models found genes mainly associated with cytokine signaling and other pathogen response pathways. The meta-analysis of lung autopsy tissue found genes associated with coagulopathy, lung fibrosis, multi-organ damage, and long COVID-19. Only genes DNAH9 and FAM216B were found perturbed in both meta-analyses. BLNK, FABP4, GRIA1, ATF3, TREM2, TPPP, TPPP3, FOS, ALB, JUNB, LMNA, ADRB2, PPARG, TNNC1, and EGR1 were identified as central elements among perturbed genes in lung autopsy and were found associated with several clinical features of severe COVID-19. Central elements were suggested as interesting targets to investigate the relation with features of COVID-19 severity, such as coagulopathy, lung fibrosis, and organ damage.

Histopathological spectrum of Pulmonary Lesions: An Autopsy based study

Context: Autopsy is a medical practice where post mortem examination of the body is performed to determine the cause of death. Internal organs are studied by gross evaluation and correlated with histopathological findings. Lung pathologies include a wide range of infectious, inflammatory, neoplastic, and occupational diseases. Determining the cause of death helps in future patient management and also helps to adopt prophylactic measures to prevent pulmonary dysfunction. AIM: This study evaluates the histopathological spectrum of pulmonary lesions in autopsies, which were the direct cause of death or incidental findings. SETTINGS AND DESIGN: This was a retrospective study conducted on lung autopsies, in the department of pathology, for a period of 4 years. MATERIALS AND METHODS: After gross examination, formalin fixed paraffi n-embedded lung sections were stained, histopathological evaluation was performed, and findings were recorded and tabulated. Statistical analysis based on frequency was done. RESULTS: This study includes a total of 240 cases. The most common age group was between 41 to 50 years, followed by 31 to 40 years. Also, a male predominance of 74.58% was noted in the study. On histopathological evaluation, 7.5% of cases were autolyzed, and 4.16% had normal histomorphology. The most common finding was mild pulmonary congestion, followed by pulmonary edema. These findings can occur secondary to a terminal event. Hence the most common finding that can cause mortality is acute pneumonia. Other common findings were emphysema, diff use alveolar damage, intra-pulmonary hemorrhage, and pulmonary vein thrombosis. CONCLUSION: Infectious pathologies are the main pulmonary lesions that lead to death. Early diagnosis and treatment can reduce these preventable causes of mortality.

SnRNA-Seq analysis reveals ten hub genes associated with alveolar epithelial cell injury during pulmonary acute respiratory distress syndrome

BackgroundAlveolar epithelial cell injury is a key factor in the occurrence and development of pulmonary acute respiratory distress syndrome (ARDSp). Yet the gene expression profile of alveolar epithelial cells of patients with ARDSp remains unclear. MethodsWe analyzed single nuclear RNA sequencing (snRNA-Seq) data from autopsy lung tissues of both ARDSp patients and healthy donors. Sequence data for type 2 alveolar epithelizal cells (AT2) were extracted by the Seurat package. Differentially expressed genes (DEGs) in AT2 were identified by the criteria |log2FC| ≥ 0.25 and P < 0.05 with DESeq2. A protein interaction network was constructed using Search Tool for the Retrieval of Interacting Genes (STRING) and Cytoscape software to identify hub genes. We then constructed an ARDSp rat model through induction by lipopolysaccharide (LPS) airway instillation. Left lung RNA was extracted and sequenced via Illumina Hiseq platforms. Analysis of the rat RNA sequencing data was then used to verify hub genes. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed on the identified hub genes. ResultsIn AT2, a total of 289 genes were identified as differentially expressed between those from ARDSp patients and healthy donors, and these included 190 upregulated and 99 downregulated genes. Ten hub genes were further identified (RPS27A, ACTG1, CAV1, HSP90AA1, HSPA5, CCND1, ITGA3, B2M, NEDD4L, and SEMA5A). There was a similar expression trend of HSPA5 between rat RNA and snRNA sequencing data. DiscussionARDSp altered the gene expression profile of AT2. The identified hub genes were enriched in biological processes mainly involved in cell growth and transformation. Relatedly, ferroptosis and autophagy are possibly involved in AT2 injury during ARDSp. These novel insights into ARDSp may aid the discovery of potential targets for the diagnosis and treatment of ARDSp.

THE CRITICAL ROLE OF THE HISTONE MODIFICATION ENZYME SETDB2 IN THE PATHOGENESIS OF ACUTE RESPIRATORY DISTRESS SYNDROME.

Introduction: Acute respiratory distress syndrome (ARDS) is a severe hypoxemic respiratory failure with a high in-hospital mortality. However, the molecular mechanisms underlying ARDS remain unclear. Recent findings have indicated that the onset of severe inflammatory diseases, such as sepsis, is regulated by epigenetic changes. We investigated the role of epigenetic changes in ARDS pathogenesis using mouse models and human samples. Methods: Acute respiratory distress syndrome was induced in a mouse model (C57BL/6 mice, myeloid cell or vascular endothelial cell [VEC]-specific SET domain bifurcated 2 [Setdb2]-deficient mice [Setdb2 ff Lyz2 Cre+ or Setdb2 ff Tie2 Cre+ ], and Cre - littermates) by intratracheal administration of lipopolysaccharide (LPS). Analyses were performed at 6 and 72 h after LPS administration. Sera and lung autopsy specimens from ARDS patients were examined. Results: In the murine ARDS model, we observed high expression of the histone modification enzyme SET domain bifurcated 2 ( Setdb2 ) in the lungs. In situ hybridization examination of the lungs revealed Setdb2 expression in macrophages and VECs. The histological score and albumin level of bronchoalveolar lavage fluid were significantly increased in Setdb2 ff Tie2 Cre+ mice following LPS administration compared with Setdb2 ff Tie2 Cre- mice, whereas there was no significant difference between the control and Setdb2 ff Lyz2 Cre+ mice. Apoptosis of VECs was enhanced in Setdb2 ff Tie2 Cre+ mice. Among the 84 apoptosis-related genes, the expression of TNF receptor superfamily member 10b ( Tnfrsf10b ) was significantly higher in Setdb2 ff Tie2 Cre+ mice than in control mice. Acute respiratory distress syndrome patients' serum showed higher SETDB2 levels than those of healthy volunteers. SETDB2 levels were negatively correlated with the partial pressure of oxygen in arterial blood/fraction of inspiratory oxygen concentration ratio. Conclusion: Acute respiratory distress syndrome elevates Setdb2 , apoptosis of VECs, and vascular permeability. Elevation of histone methyltransferase Setdb2 suggests the possibility to histone change and epigenetic modification. Thus, Setdb2 may be a novel therapeutic target for controlling the pathogenesis of ARDS.

Bi-directional epithelial-immune communication amplifies inflammasome activation and IL-6 release during SARS-CoV-2 infection

Abstract Increased levels of the pro-inflammatory cytokines IL-1β and IL-6 are linked to severe COVID-19. Here, we investigate the contributions of viral host cells, primary human airway epithelia (HAE), and immune bystanders, peripheral blood mononuclear cells (PBMCs), in the production of these cytokines. Despite having functional inflammasomes and supporting viral replication, HAE do not secrete IL-1β upon SARS-CoV-2 infection. PBMCs do not support productive viral replication, but the SARS-CoV-2 envelope (E) protein primes inflammasomes through stimulation of TLR2. To activate inflammasomes in PBMCs, SARS-CoV-2-infected HAE provide a second signal in the form of damage-associated molecular patterns (DAMPs), which includes mitochondrial and genomic DNA. Co-culture of PBMCs with infected epithelial cells stimulates IL-1β release, while addition of benzonase, STING, or caspase-1 inhibitors, but not NLRP3 inhibitors, abrogates this response. In turn, IL-1β stimulates IL-6 secretion from both populations with a robust response from HAE. Thus, while infection in either cell type in isolation does not yield IL-1β or IL-6, immune bystander detection of SARS-CoV-2 infection in the epithelium stimulates both IL-1β and IL-6 production, amplifying pro-inflammatory cytokine production through cell-cell communication. This circuit is reflected in patient data, as COVID-19 autopsy lungs show hallmarks of inflammasome priming and activation in myeloid populations lacking SARS-CoV-2 antigens. Meta-analysis of single cell RNA sequencing (scRNAseq) data reveals discordant, exacerbated priming of inflammasomes in myeloid cells from severe but not mild COVID-19 patients, indicating this circuit is intensified in severe disease. Supported by grants from NIH R56 AI158314, R01 AI158314, AI029564, AI141333 and CA232109 to J.P.-Y.T; NCI T32CA071341 to K.C.B.; UH3 HL123645, R01 HL136961, P30 DK 065988, P01 HL108808, and from the Cystic Fibrosis Foundation (CFF) BOUCHE19R0 to T.A. and R.C.B; CFF grant BOUCHE19XX0 to R.C.B. and K.O.; CFF grant OKUDA20G0 KO; NC Policy Collaboratory, NIH R01AI157253, and U19 AI100625 to M. T. H.; NSF GRFP 2019255197 to J.F.L. T.A. is a Japan Society for the Promotion of Science Overseas Research Fellow. Y.X. is supported by NSF DMS-191290 and NSF IOS 2107215. Y.X and Y.L.L. are supported by NIH grants R01DE026728 and R01DE031951. Some BSL3 work was performed in the Duke Regional Biocontainment Laboratory (Duke RBL) which received partial support for construction from NIH/NIAID (UC6AI058607).

The Histological and Immunopathological Landscape of Lung Autopsy Sample of COVID 19.

The purpose of this study is to explain the reason for the death histologically by comparing normal lungs with infected ones. The lung autopsy samples were taken from 12 adult patients in Erbil forensic medicine diagnosed before with covid 19 which also consider a reason for death. For histological examinations and the identification of SARS-CoV-2 RNA, autopsy materials were collected, fixed in 4% neutral formaldehyde for at least 24 hours, and sampled as formalin-fixed, paraffin-embedded (FFPE) tissues. Staining with hematoxylin and eosin (H&E) was done in accordance with protocol. Based on the results of immunopathology in deceased people, it was shown that there was a strong positive reaction with BCL2 antibody in the cytoplasm of lung alveolar cells compared to the lungs of healthy people. Also, a positive reaction with catenin antibody, SMA antibody had occurred in the cytoplasm of lung alveolar cells in the lungs of patients, and finally, it was shown that the Vimentin antibody reaction was present in the cytoplasm of lung alveolar cells of patients. All four investigated factors, BCL2, catenin, SMA antibody and vimentin antibody, have played an important role in the inflammation and fibrosis of lung tissue in patients with COVID, and the combination of these four factors together has played a significant role in worsening the symptoms and worsening of the disease.

Generation and Functional Analysis of Defective Viral Genomes during SARS-CoV-2 Infection.

Defective viral genomes (DVGs) have been identified in many RNA viruses as a major factor influencing antiviral immune response and viral pathogenesis. However, the generation and function of DVGs in SARS-CoV-2 infection are less known. In this study, we elucidated DVG generation in SARS-CoV-2 and its relationship with host antiviral immune response. We observed DVGs ubiquitously from transcriptome sequencing (RNA-seq) data sets of in vitro infections and autopsy lung tissues of COVID-19 patients. Four genomic hot spots were identified for DVG recombination, and RNA secondary structures were suggested to mediate DVG formation. Functionally, bulk and single-cell RNA-seq analysis indicated the interferon (IFN) stimulation of SARS-CoV-2 DVGs. We further applied our criteria to the next-generation sequencing (NGS) data set from a published cohort study and observed a significantly higher amount and frequency of DVG in symptomatic patients than those in asymptomatic patients. Finally, we observed exceptionally diverse DVG populations in one immunosuppressive patient up to 140 days after the first positive test of COVID-19, suggesting for the first time an association between DVGs and persistent viral infections in SARS-CoV-2. Together, our findings strongly suggest a critical role of DVGs in modulating host IFN responses and symptom development, calling for further inquiry into the mechanisms of DVG generation and into how DVGs modulate host responses and infection outcome during SARS-CoV-2 infection. IMPORTANCE Defective viral genomes (DVGs) are generated ubiquitously in many RNA viruses, including SARS-CoV-2. Their interference activity to full-length viruses and IFN stimulation provide the potential for them to be used in novel antiviral therapies and vaccine development. SARS-CoV-2 DVGs are generated through the recombination of two discontinuous genomic fragments by viral polymerase complex, and this recombination is also one of the major mechanisms for the emergence of new coronaviruses. Focusing on the generation and function of SARS-CoV-2 DVGs, these studies identify new hot spots for nonhomologous recombination and strongly suggest that the secondary structures within viral genomes mediate the recombination. Furthermore, these studies provide the first evidence for IFN stimulation activity of de novo DVGs during natural SARS-CoV-2 infection. These findings set up the foundation for further mechanism studies of SARS-CoV-2 recombination and provide evidence to harness the immunostimulatory potential of DVGs in the development of a vaccine and antivirals for SARS-CoV-2.

Circulating SARS-CoV-2+ megakaryocytes are associated with severe viral infection in COVID-19

AbstractSeveral independent lines of evidence suggest that megakaryocytes are dysfunctional in severe COVID-19. Herein, we characterized peripheral circulating megakaryocytes in a large cohort of inpatients with COVID-19 and correlated the subpopulation frequencies with clinical outcomes. Using peripheral blood, we show that megakaryocytes are increased in the systemic circulation in COVID-19, and we identify and validate S100A8/A9 as a defining marker of megakaryocyte dysfunction. We further reveal a subpopulation of S100A8/A9+ megakaryocytes that contain severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protein and RNA. Using flow cytometry of peripheral blood and in vitro studies on SARS-CoV-2–infected primary human megakaryocytes, we demonstrate that megakaryocytes can transfer viral antigens to emerging platelets. Mechanistically, we show that SARS-CoV-2–containing megakaryocytes are nuclear factor κB (NF-κB)-activated, via p65 and p52; express the NF-κB–mediated cytokines interleukin-6 (IL-6) and IL-1β; and display high surface expression of Toll-like receptor 2 (TLR2) and TLR4, canonical drivers of NF-κB. In a cohort of 218 inpatients with COVID-19, we correlate frequencies of megakaryocyte subpopulations with clinical outcomes and show that SARS-CoV-2–containing megakaryocytes are a strong risk factor for mortality and multiorgan injury, including respiratory failure, mechanical ventilation, acute kidney injury, thrombotic events, and intensive care unit admission. Furthermore, we show that SARS-CoV-2+ megakaryocytes are present in lung and brain autopsy tissues from deceased donors who had COVID-19. To our knowledge, this study offers the first evidence implicating SARS-CoV-2+ peripheral megakaryocytes in severe disease and suggests that circulating megakaryocytes warrant investigation in inflammatory disorders beyond COVID-19.

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.

Inhibition of the mitochondrial pyruvate carrier simultaneously mitigates hyperinflammation and hyperglycemia in COVID-19.

The relationship between diabetes and coronavirus disease 2019 (COVID-19) is bidirectional: Although individuals with diabetes and high blood glucose (hyperglycemia) are predisposed to severe COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can also cause hyperglycemia and exacerbate underlying metabolic syndrome. Therefore, interventions capable of breaking the network of SARS-CoV-2 infection, hyperglycemia, and hyperinflammation, all factors that drive COVID-19 pathophysiology, are urgently needed. Here, we show that genetic ablation or pharmacological inhibition of mitochondrial pyruvate carrier (MPC) attenuates severe disease after influenza or SARS-CoV-2 pneumonia. MPC inhibition using a second-generation insulin sensitizer, MSDC-0602K (MSDC), dampened pulmonary inflammation and promoted lung recovery while concurrently reducing blood glucose levels and hyperlipidemia after viral pneumonia in obese mice. Mechanistically, MPC inhibition enhanced mitochondrial fitness and destabilized hypoxia-inducible factor-1α, leading to dampened virus-induced inflammatory responses in both murine and human lung macrophages. We further showed that MSDC enhanced responses to nirmatrelvir (the antiviral component of Paxlovid) to provide high levels of protection against severe host disease development after SARS-CoV-2 infection and suppressed cellular inflammation in human COVID-19 lung autopsies, demonstrating its translational potential for treating severe COVID-19. Collectively, we uncover a metabolic pathway that simultaneously modulates pulmonary inflammation, tissue recovery, and host metabolic health, presenting a synergistic therapeutic strategy to treat severe COVID-19, particularly in patients with underlying metabolic disease.

Robust single-cell matching and multimodal analysis using shared and distinct features

The ability to align individual cellular information from multiple experimental sources is fundamental for a systems-level understanding of biological processes. However, currently available tools are mainly designed for single-cell transcriptomics matching and integration, and generally rely on a large number of shared features across datasets for cell matching. This approach underperforms when applied to single-cell proteomic datasets due to the limited number of parameters simultaneously accessed and lack of shared markers across these experiments. Here, we introduce a cell-matching algorithm, matching with partial overlap (MARIO) that accounts for both shared and distinct features, while consisting of vital filtering steps to avoid suboptimal matching. MARIO accurately matches and integrates data from different single-cell proteomic and multimodal methods, including spatial techniques and has cross-species capabilities. MARIO robustly matched tissue macrophages identified from COVID-19 lung autopsies via codetection by indexing imaging to macrophages recovered from COVID-19 bronchoalveolar lavage fluid by cellular indexing of transcriptomes and epitopes by sequencing, revealing unique immune responses within the lung microenvironment of patients with COVID.

An epithelial-immune circuit amplifies inflammasome and IL-6 responses to SARS-CoV-2

Elevated levels of cytokines IL-1β and IL-6 are associated with severe COVID-19. Investigating the underlying mechanisms, we find that while primary human airway epithelia (HAE) have functional inflammasomes and support SARS-CoV-2 replication, they are not the source of IL-1β released upon infection. In leukocytes, the SARS-CoV-2 E protein upregulates inflammasome gene transcription via TLR2 to prime, but not activate, inflammasomes. SARS-CoV-2-infected HAE supply a second signal, which includes genomic and mitochondrial DNA, to stimulate leukocyte IL-1β release. Nuclease treatment, STING, and caspase-1 inhibition but not NLRP3 inhibition blocked leukocyte IL-1β release. After release, IL-1β stimulates IL-6 secretion from HAE. Therefore, infection alone does not increase IL-1β secretion by either cell type. Rather, bi-directional interactions between the SARS-CoV-2-infected epithelium and immune bystanders stimulates both IL-1β and IL-6, creating a pro-inflammatory cytokine circuit. Consistent with these observations, patient autopsy lungs show elevated myeloid inflammasome gene signatures in severe COVID-19.

Objective evaluation of chest findings in infants by postmortem computed tomography

PurposeThe purpose of this study was to review the findings of computed tomography (CT) performed early postmortem on infants and to clarify the postmortem CT lung findings that occur in the absence of abnormal histopathological findings. Materials and methodsFrom July 2016 to March 2022, 72 infants were autopsied with postmortem CT (41 boys 31 girls, aged 0–36 (mean 8.2) months). Autopsy and postmortem CT lung findings were compared with the causes of death identified by the autopsies, namely sudden infant death syndrome (n = 37), acute circulatory system disease (18), drowning (7), asphyxia (5), and dehydration/undernutrition (5). ResultsThe %aerated lung volume (−700 HU or less) ranged from 0 % to 33 % (mean 1.5 %, median 0 %), being <1 % in 61 cases (84.7 %) and >3 % in 3/5 (60 %) of the dehydration/undernutrition group. The dehydration/undernutrition group showed significant preservation of lung field air content compared with the other causes of death groups (p < 0.05). Receiver characteristic curve analysis showed a cut off value of 0.8 % and area under the curve of 0.88806. The drowning group had significantly greater pleural cavity fluid retention than the other causes of death groups (p < 0.05). No correlation was found between postmortem interval and pleural cavity fluid retention. However, resuscitation time and pleural cavity fluid retention were correlated. ConclusionEvaluation of CT values on postmortem lung fields of infants usually reveals a marked decrease in air content. When air content exceeds 0.8% on infant postmortem CT, dehydration/undernutrition should be considered in the differential diagnosis.

Study of histopathological spectrum of non-neoplastic lesions of the lung in autopsy specimen

Background: Lungs are the major organ involved in infectious and occupational diseases almost secondarily involved in all forms of terminal diseases. Autopsy plays an important role in identifying and understanding the pathology of various respiratory diseases and lung lesions to find out the parenchymal pathology. Aims and Objectives: This study aims to study the histopathological spectrum of non-neoplastic lung lesions in medicolegal autopsy and to assess the frequency of spectrum of lung lesions. Materials and Methods: The present retrospective study was carried out in the Department of Pathology, Shyam Shah Medical College, Rewa, M.P., for a period of 18 months from July 2020 to January 2022. All 98 consecutive specimens of medicolegal autopsy were included with age from newborn to 70 years irrespective of gender and cause of death. The results were analyzed based on gross and microscopic findings. Results: Among the 98 cases studied, 82 cases (84%) were of diseased and 16 cases (16%) were of non-diseased lung. The most common age group affected was 30–39 years with 30% of affected cases followed by 20–29 years with 21% of affected cases. Among 82 cases, the most common pulmonary lesion was pneumonia in 46% (45/98) of the total cases followed by congestion and edema seen in 22% (21/98) of the cases. Conclusion: Histopathological study of lung autopsy helps in providing information for clinical diagnosis of non-neoplastic lung lesions that act as a tool for better clinical assessment and help to establish a correct prophylactic measure. The histopathological examination (HPE) helps in establishing the final cause of death. The HPE helps in establishing the final cause of death. Therefore, autopsy study is very helpful in refining the vision and diagnostic setup for better evaluation.

Applying imaging mass spectrometry to define the N-glycan profiles of co-localized virus and immune cell infiltrates in post-COVID-19 infected lung autopsy tissues

The current COVID-19 pandemic is characterized by a broad range of disease severity in patients. This diversity in clinical manifestations has complicated our understanding of the SARS-CoV-2 pathogenesis and highlights the significance of an individual’s ability to mount an effective viral immune response. Glycosylation is a common post-translational modification occurring in complex organisms and is imperative for immune cell function. In this study, a combination approach with immunohistochemistry (IHC) and matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) was utilized to determine the spatial distribution of N-glycans and immune cell populations in COVID-19 lung tissues. Tissues from seven SARS-CoV-2, PCR + donors were analyzed. Tissues represented a spectrum of time spent on ventilators which was reflected in their respective viral infection status and lung pathologies. N-glycan distributions in the MALDI-IMS images were then correlated with H&amp;amp;E staining and IHC of SARS-CoV-2 spike protein, CD4, CD8, CD163 and CD11b. Distinct and shared N-glycan signatures were identified in association with specific immune cell types, and their co-localization with the viral spike protein. Additionally, we observed unique patterns of α2,3-linked and α2,6-linked sialic acid glycans that associated with both immune cell populations and fibrotic regions within the tissue architecture. N-glycan MALDI-IMS is an effective tool to further understand tissue-localized immune cell populations in response to emerging viral pathogens such as SARS-CoV-2.