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Coronavirus disease 2019 (COVID-19) is a global public health emergency with many clinical facets, and new knowledge about its pathogenetic mechanisms is deemed necessary; among these, there are certainly coagulation disorders. In the history of medicine, autopsies and tissue sampling have played a fundamental role in order to understand the pathogenesis of emerging diseases, including infectious ones; compared to the past, histopathology can be now expanded by innovative techniques and modern technologies. For the first time in worldwide literature, we provide a detailed postmortem and biopsy report on the marked increase, up to 1 order of magnitude, of naked megakaryocyte nuclei in the bone marrow and lungs from serious COVID-19 patients. Most likely related to high interleukin-6 serum levels stimulating megakaryocytopoiesis, this phenomenon concurs to explain well the pulmonary abnormal immunothrombosis in these critically ill patients, all without molecular or electron microscopy signs of megakaryocyte infection.

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The tumor immune microenvironment (TME) and immune checkpoints have been reported to serve a role in the pathogenesis of malignant mesothelioma (MM) and treatment outcome. Additionally, mismatch Repair (MMR) deficiency appears to enhance the response to checkpoints blockade in several tumors. The aim of the present study was to analyze programmed death-1 ligand 1 (PD-L1) expression in MM and to characterize the TME. This could help to understand the immune response, and evaluate its prognostic and predictive values. We also investigated MMR protein expression. We retrospectively analyzed 55 mesotheliomas to determine PD-L1, CD4 + , CD8 + , mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), mutS homolog 6 (MSH6) and PMS1 homolog 2, mismatch repair system component (PMS2) expression. We used an immunoscore (1+, 2+ and 3+) to evaluate tumor-infiltrating lymphocytes (TILs). TILs were observed in all but two samples (53/55); the majority had an immunoscore 1+ (30/53), while 2+/3+ was reported for 23/53 samples. A predominance of CD8 + was highlighted in 8 cases (15%). PD-L1 expression of ≥1% on tumor cells was displayed in 40 cases; in 9 of these, ≥50% expression was reported. Of note, alterations in MMR staining was not observed. In addition, survival analysis revealed that epithelioid subtype was associated with better prognosis. We observed a trend towards poorer prognosis for ≥50% PD-L1 expression on tumor cells, lower immunoscore (1+) and CD8 + TIL predominance. The present study highlighted the importance of exploring the TME and the standardization of PD-L1 assessment guidelines to apply in the field of immunotherapy.

Aberrant methylation of multiple promoter CpG islands could be related to the biology of ovarian tumors and its determination could help to improve treatment strategies. DNA methylation profiling was performed using the Methylation Ligation-dependent Macroarray (MLM), an array-based analysis. Promoter regions of 41 genes were analyzed in 102 ovarian tumors and 17 normal ovarian samples. An average of 29% of hypermethylated promoter genes was observed in normal ovarian tissues. This percentage increased slightly in serous, endometrioid, and mucinous carcinomas (32%, 34%, and 45%, respectively), but decreased in germ cell tumors (20%). Ovarian tumors had methylation profiles that were more heterogeneous than other epithelial cancers. Unsupervised hierarchical clustering identified four groups that are very close to the histological subtypes of ovarian tumors. Aberrant methylation of three genes (BRCA1, MGMT, and MLH1), playing important roles in the different DNA repair mechanisms, were dependent on the tumor subtype and represent powerful biomarkers for precision therapy. Furthermore, a promising relationship between hypermethylation of MGMT, OSMR, ESR1, and FOXL2 and overall survival was observed. Our study of DNA methylation profiling indicates that the different histotypes of ovarian cancer should be treated as separate diseases both clinically and in research for the development of targeted therapies.