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Post-acute cardiac sequelae, following SARS-CoV-2 infection, are well recognized as complications of COVID-19. We have previously shown the persistence of autoantibodies against antigens in skin, muscle, and heart in individuals following severe COVID-19; the most common staining on skin tissue displayed an inter-cellular cement pattern consistent with antibodies against desmosomal proteins. Desmosomes play a critical role in maintaining the structural integrity of tissues. For this reason, we analyzed desmosomal protein levels and the presence of anti-desmoglein (DSG) 1, 2, and 3 antibodies in acute and convalescent sera from patients with COVID-19 of differing clinical severity. We find increased levels of DSG2 protein in sera from acute COVID-19 patients. Furthermore, we find that DSG2 autoantibody levels are increased significantly in convalescent sera following severe COVID-19 but not in hospitalized patients recovering from influenza infection or healthy controls. Levels of autoantibody in sera from patients with severe COVID-19 were comparable to levels in patients with non-COVID-19-associated cardiac disease, potentially identifying DSG2 autoantibodies as a novel biomarker for cardiac damage. To determine if there was any association between severe COVID-19 and DSG2, we stained post-mortem cardiac tissue from patients who died from COVID-19 infection. This confirmed DSG2 protein within the intercalated discs and disruption of the intercalated disc between cardiomyocytes in patients who died from COVID-19. Our results reveal the potential for DSG2 protein and autoimmunity to DSG2 to contribute to unexpected pathologies associated with COVID-19 infection. We find raised levels of anti-DSG2 autoantibodies in sera from individuals following severe COVID-19. Staining of post-mortem cardiac tissue from individuals that died from COVID-19 with an anti-DSG2 antibody revealed disruption of the intercalated disc between cardiomyocytes that was consistent with separation of the DSG2 protein homodimer. Our results reveal the potential for DSG2 protein and autoimmunity to DSG2 to contribute to unexpected pathologies associated with COVID-19 infection. [ABSTRACT FROM AUTHOR]

B lymphocytes are multitasking cells that direct the immune response by producing pro- or anti-inflammatory cytokines, by presenting processed antigen for T cell activation and co-stimulation, and by turning into antibody-secreting cells. These functions are important to control infection in the liver but can also exacerbate tissue damage and fibrosis as part of persistent inflammation that can lead to end stage disease requiring a transplant. In transplantation, immunosuppression increases the incidence of lymphoma and often this is of B cell origin. In this review we bring together information on liver B cell biology from different liver diseases, including alcohol-related and metabolic fatty liver disease, autoimmune hepatitis, primary biliary and primary sclerosing cholangitis, viral hepatitis and, in infants, biliary atresia. We also discuss the impact of B cell depletion therapy in the liver setting. Taken together, our analysis shows that B cells are important in the pathogenesis of liver diseases and that further research is necessary to fully characterise the human liver B cell compartment. [ABSTRACT FROM AUTHOR]

Background: Pre-clinical research with multi-potent adult progenitor cells (MAPC® cells, Multistem, Athersys Inc., Cleveland, Ohio) suggests their potential as an anti-inflammatory and immunomodulatory therapy in organ transplantation. Normothermic machine perfusion of the liver (NMP-L) has been proposed as a way of introducing therapeutic agents into the donor organ. Delivery of cellular therapy to human donor livers using this technique has not yet been described in the literature. The primary objectives of this study were to develop a technique for delivering cellular therapy to human donor livers using NMP-L and demonstrate engraftment. Methods: Six discarded human livers were perfused for 6 h at 37°C using the Liver Assist (Organ Assist, Groningen). 50 × 106 CMPTX-labeled MAPC cells were infused directly into the right lobe via the hepatic artery (HA, n = 3) or portal vein (PV, n = 3) over 20 min at different time points during the perfusion. Perfusion parameters were recorded and central and peripheral biopsies were taken at multiple time-points from both lobes and subjected to standard histological stains and confocal microscopy. Perfusate was analyzed using a 35-plex multiplex assay and proteomic analysis. Results: There was no detrimental effect on perfusion flow parameters on infusion of MAPC cells by either route. Three out of six livers met established criteria for organ viability. Confocal microscopy demonstrated engraftment of MAPC cells across vascular endothelium when perfused via the artery. 35-plex multiplex analysis of perfusate yielded 13 positive targets, 9 of which appeared to be related to the infusion of MAPC cells (including Interleukin's 1b, 4, 5, 6, 8, 10, MCP-1, GM-CSF, SDF-1a). Proteomic analysis revealed 295 unique proteins in the perfusate from time-points following the infusion of cellular therapy, many of which have strong links to MAPC cells and mesenchymal stem cells in the literature. Functional enrichment analysis demonstrated their immunomodulatory potential. Conclusion: We have demonstrated that cells can be delivered directly to the target organ, prior to host immune cell population exposure and without compromising the perfusion. Transendothelial migration occurs following arterial infusion. MAPC cells appear to secrete a host of soluble factors that would have anti-inflammatory and immunomodulatory benefits in a human model of liver transplantation. [ABSTRACT FROM AUTHOR]

Toxic substances and microbial or food-derived antigens continuously challenge the liver, which is tasked with their safe neutralization. This vital organ is also important for the removal of apoptotic immune cells during inflammation and has been previously described as a "graveyard" for dying lymphocytes. The clearance of apoptotic and necrotic cells is known as efferocytosis and is a critical liver function to maintain tissue homeostasis. Much of the research into this form of immunological control has focused on Kupffer cells, the liver-resident macrophages. However, hepatocytes (and other liver resident cells) are competent efferocytes and comprise 80% of the liver mass. Little is known regarding the mechanisms of apoptotic and necrotic cell capture by epithelia, which lack key receptors that mediate phagocytosis in macrophages. Herein, we discuss recent developments that increased our understanding of efferocytosis in tissues, with a special focus on the liver parenchyma. We discuss the impact of efferocytosis in health and in inflammation, highlighting the role of phagocytic epithelia. [ABSTRACT FROM AUTHOR]

Introduction CD248 (endosialin) is a stromal cell marker expressed on fibroblasts and pericytes. During liver injury, myofibroblasts are the main source of fibrotic matrix. Objective To determine the role of CD248 in the development of liver fibrosis in the rodent and human setting. Design CD248 expression was studied by immunostaining and quantitative PCR in both normal and diseased human and murine liver tissue and isolated hepatic stellate cells (HSCs). Hepatic fibrosis was induced in CD248-/- and wild-type controls with carbon tetrachloride (CCl4) treatment. Results Expression of CD248 was seen in normal liver of humans and mice but was significantly increased in liver injury using both immunostaining and gene expression assays. CD248 was co-expressed with a range of fibroblast/HSC markers including desmin, vimentin and α-smooth muscle actin (α-SMA) in murine and human liver sections. CD248 expression was restricted to isolated primary murine and human HSC. Collagen deposition and α-SMA expression, but not inflammation and neoangiogenesis, was reduced in CD248-/- mice compared with wild-type mice after CCl4 treatment. Isolated HSC from wild-type and CD248-/- mice expressed platelet-derived growth factor receptor α (PDGFR-α) and PDGFR-β at similar levels. As expected, PDGF-BB stimulation induced proliferation of wild-type HSC, whereas CD248-/- HSC did not demonstrate a proliferative response to PDGF-BB. Abrogated PDGF signalling in CD248-/- HSC was confirmed by significantly reduced c-fos expression in CD248-/- HSC compared with wild-type HSC. Conclusions Our data show that deletion of CD248 reduces susceptibility to liver fibrosis via an effect on PDGF signalling, making it an attractive clinical target for the treatment of liver injury. [ABSTRACT FROM AUTHOR]

Successful and consistent isolation of primary human hepatocytes remains a challenge for both cell-based therapeutics/ transplantation and laboratory research. Several centres around the world have extensive experience in the isolation of human hepatocytes from non-diseased livers obtained from donor liver surplus to surgical requirement or at hepatic resection for tumours. These livers are an important but limited source of cells for therapy or research. The capacity to isolate cells from diseased liver tissue removed at transplantation would substantially increase availability of cells for research. However no studies comparing the outcome of human hepatocytes isolation from diseased and non-diseased livers presently exist. Here we report our experience isolating human hepatocytes from organ donors, non-diseased resected liver and cirrhotic tissue. We report the cell yields and functional qualities of cells isolated from the different types of liver and demonstrate that a single rigorous protocol allows the routine harvest of good quality primary hepatocytes from the most commonly accessible human liver tissue samples. [ABSTRACT FROM AUTHOR]

Aim: To study simultaneously the actions of maspin and CXCR4, which share several similar pathways in cancer, including apoptosis and angiogenesis. Methods: Our material consisted of 151 invasive breast carcinomas arranged in a tissue microarray setting. Maspin and CXCR4 expression was evaluated by immunohistochemistry. Microvessel density was assessed by CD34 immunodetection and apoptosis by the Tdt-mediated dUTP nick end labelling assay. Results: Maspin expression was related to CXCR4 expression, apoptosis, patient age and the Nottingham prognostic index. The expression of both maspin and CXCR4 progressively increased in high-grade tumours. In patients with lymph node negative breast cancer, maspin overexpression was associated with increased risk of death. High CXCR4 expression was associated with prolonged survival of patients with high maspin expression. Conclusions: Our results show that maspin overexpression could prove to be a potentially useful marker, especially for the clinically important group of patients with lymph node negative breast cancer. The expression of CXCR4 is of less significance in our study, but may be informative for specific patient subsets or in a longer time frame. [ABSTRACT FROM AUTHOR]

The oncogenic Epstein-Barr virus (EBV)-encoded latent infection membrane protein 1 (LMP1) constitutively activates the ‘canonical’ NF-?B pathway that involves the phosphorylation and degradation of I?Ba downstream of the I?B kinases (IKKs). In this study, we show that LMP1 also promotes the proteasome-mediated proteolysis of p100 NF-?B2 resulting in the generation of active p52, which translocates to the nucleus in complex with the p65 and RelB NF-?B subunits. LMP1-induced NF-?B transactivation is reduced in nf-kb2-/- mouse embryo fibroblasts, suggesting that p100 processing contributes to LMP1-mediated NF-?B transcriptional effects. This pathway is likely to operate in vivo, as the expression of LMP1 in primary EBV-positive Hodgkin's lymphoma and nasopharyngeal carcinoma biopsies correlates with the nuclear accumulation of p52. Interestingly, while the ability of LMP1 to activate the canonical NF-?B pathway is impaired in cells lacking IKK?/NEMO, the regulatory subunit of the IKK complex, p100 processing remains unaffected. As a result, nuclear translocation of p52, but not p65, occurs in the absence of IKK?. These data point to the existence of a novel signalling pathway that regulates NF-?B in LMP1-expressing cells, and may thereby play a role in both oncogenic transformation and the establishment of persistent EBV infection.Oncogene (2003) 22, 7557-7569. doi:10.1038/sj.onc.1207120 [ABSTRACT FROM AUTHOR]

The Drosophila tumour suppressor discs large (Dlg) is a cell-junction localized protein that is required for the maintenance of epithelial cyto-architecture and the negative control of cell proliferation. The mammalian homologue is likely to have a similar mode of action, and therefore functional perturbation of this protein may be linked to the development of epithelial-derived cancers. The finding that several unrelated viral oncoproteins, including the E6 protein of oncogenic human papillomaviruses, bind to the human homologue of Dlg (hDlg) supports this proposition. Employing immunohistochemistry, we show that in uterine cervical squamous epithelia, prominent localization of hDlg at sites of intercellular contact occurs in cells that have left the proliferating basal cell layers and begun maturation. The presence of hDlg at sites of cell:cell contact diminishes, whilst intracellular cytoplasmic levels increase significantly in high-grade, but not low-grade, cervical neoplasias. In invasive squamous cell carcinomas, total cellular hDlg levels are greatly reduced. Our data suggest that loss of hDlg at sites of intercellular contact may be an important step in the development of epithelial cancers. [ABSTRACT FROM PUBLISHER]

Summary. Interleukin 6 (IL-6) is a potent immunomodulatory cytokine that has pathogenic and prognostic significance in a number of disorders. Previous studies in Hodgkin's disease (HD) have demonstrated the association between elevated serum levels of IL-6 and unfavourable prognosis, including advanced stage and the presence of ‘B’ symptoms and with reduced survival. Although IL-6 expression has been demonstrated in both the malignant Hodgkin/Reed–Sternberg (HRS) cells and in the various non-malignant cells present in HD biopsies, a relationship between expression of IL-6 by the tumour and outcome measures has not been established. The study group comprised of 97 patients with advanced HD who were recruited to two related clinical trials. IL-6 expression was determined on paraffin-wax sections of biopsy material by means of an immunohistochemical assay. Of the 97 patients, 27 (28%) showed staining for IL-6 in HRS cells. IL-6 expression by HRS cells was significantly correlated with a decreased likelihood of achieving a complete response to chemotherapy (P = 0·02) and with an increased prevalence of ‘B’ symptoms (P = 0·04). IL-6 expression by HRS cells was not associated with Epstein–Barr virus status (P = 0·57). In summary, the results suggest that IL-6 expression by HRS cells may contribute to the presence of ‘B’ symptoms and to a decreased likelihood to achieve a complete remission in HD patients. [ABSTRACT FROM AUTHOR]

CD4+ T cells play critical roles in directing immunity, both as T helper and as regulatory T (Treg) cells. Here, we demonstrate that hepatocytes can modulate T cell populations through engulfment of live CD4+ lymphocytes. We term this phenomenon enclysis to reflect the specific enclosure of CD4+ T cells in hepatocytes. Enclysis is selective for CD4+ but not CD8+ cells, independent of antigen-specific activation, and occurs in human hepatocytes in vitro , ex vivo , and in vivo. Intercellular adhesion molecule 1 (ICAM-1) facilitates T cell early adhesion and internalization, whereas hepatocytes form membrane lamellipodia or blebs to mediate engulfment. T cell internalization is unaffected by wortmannin and Rho kinase inhibition. Hepatocytes engulf Treg cells more efficiently than non-Treg cells, but Treg cell-containing vesicles preferentially acidify overnight. Thus, enclysis is a biological process with potential effects on immunomodulation and opens a new field for research to fully understand CD4+ T cell dynamics in liver inflammation. • Hepatocytes engulf live CD4+ T cells, with a preference for regulatory cells • We called this process enclysis and compared it with known cell-in-cell processes • ICAM-1 and β-catenin accumulated at the point of T cell engulfment • Enclysis was seen in health, in liver cancer, and especially in autoimmune disorders Enclysis describes the enclosure of live CD4+ T cells in intracellular vesicles. Davies et al. show that hepatocytes engulf regulatory T (Treg) cells and preferentially delete them. Enclysis is distinct from entosis, efferocytosis, and suicidal emperipolesis and may be targeted to control T cell populations in the liver during inflammation. [ABSTRACT FROM AUTHOR]