Cardiac myosin-specific autoimmune T cells contribute to immune-checkpoint-inhibitor-associated myocarditis.

Immune checkpoint inhibitors (ICIs) are an effective therapy for various cancers; however, they can induce immune-related adverse events (irAEs) as a side effect. Myocarditis is an uncommon, but fatal, irAE caused after ICI treatments. Currently, the mechanism of ICI-associated myocarditis is unclear. Here, we show the development of myocarditis in A/J mice induced by anti-PD-1 monoclonal antibody (mAb) administration alone without tumor cell inoculation, immunization, or viral infection. Mice with myocarditis have increased cardiac infiltration, elevated cardiac troponin levels, and arrhythmia. Anti-PD-1 mAb treatment also causes irAEs in other organs. Autoimmune T cells recognizing cardiac myosin are activated and increased in mice with myocarditis. Notably, cardiac myosin-specific T cells are present in naive mice, showing a phenotype of antigen-experienced T cells. Collectively, we establish a clinically relevant mouse model for ICI-associated myocarditis and find a contribution of cardiac myosin-specific T cells to ICI-associated myocarditis development and pathogenesis.

High-Speed Human Temporal Bone Sectioning for the Assessment of COVID-19-Associated Middle Ear Pathology.

Histopathologic analysis of human temporal bone sections is a fundamental technique for studying inner and middle ear pathology. Temporal bone sections are prepared by postmortem temporal bone harvest, fixation, decalcification, embedding, and staining. Due to the density of the temporal bone, decalcification is a time-consuming and resource-intensive process; complete tissue preparation may take 9-10 months on average. This slows otopathology research and hinders time-sensitive studies, such as those relevant to the COVID-19 pandemic. This paper describes a technique for the rapid preparation and decalcification of temporal bone sections to speed tissue processing. Temporal bones were harvested postmortem using standard techniques and fixed in 10% formalin. A precision microsaw with twin diamond blades was used to cut each section into three thick sections. Thick temporal bone sections were then decalcified in decalcifying solution for 7-10 days before being embedded in paraffin, sectioned into thin (10 µm) sections using a cryotome, and mounted on uncharged slides. Tissue samples were then deparaffinized and rehydrated for antibody staining (ACE2, TMPRSS2, Furin) and imaged. This technique reduced the time from harvest to tissue analysis from 9-10 months to 10-14 days. High-speed temporal bone sectioning may increase the speed of otopathology research and reduce the resources necessary for tissue preparation, while also facilitating time-sensitive studies such as those related to COVID-19.

Endothelial thrombomodulin downregulation caused by hypoxia contributes to severe infiltration and coagulopathy in COVID-19 patient lungs.

BACKGROUND: Thromboembolism is a life-threatening manifestation of coronavirus disease 2019 (COVID-19). We investigated a dysfunctional phenotype of vascular endothelial cells in the lungs during COVID-19. METHODS: We obtained the lung specimens from the patients who died of COVID-19. The phenotype of endothelial cells and immune cells was examined by flow cytometry and immunohistochemistry (IHC) analysis. We tested the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the endothelium using IHC and electron microscopy. FINDINGS: The autopsy lungs of COVID-19 patients exhibited severe coagulation abnormalities, immune cell infiltration, and platelet activation. Pulmonary endothelial cells of COVID-19 patients showed increased expression of procoagulant von Willebrand factor (VWF) and decreased expression of anticoagulants thrombomodulin and endothelial protein C receptor (EPCR). In the autopsy lungs of COVID-19 patients, the number of macrophages, monocytes, and T cells was increased, showing an activated phenotype. Despite increased immune cells, adhesion molecules such as ICAM-1, VCAM-1, E-selectin, and P-selectin were downregulated in pulmonary endothelial cells of COVID-19 patients. Notably, decreased thrombomodulin expression in endothelial cells was associated with increased immune cell infiltration in the COVID-19 patient lungs. There were no SARS-CoV-2 particles detected in the lung endothelium of COVID-19 patients despite their dysfunctional phenotype. Meanwhile, the autopsy lungs of COVID-19 patients showed SARS-CoV-2 virions in damaged alveolar epithelium and evidence of hypoxic injury. INTERPRETATION: Pulmonary endothelial cells become dysfunctional during COVID-19, showing a loss of thrombomodulin expression related to severe thrombosis and infiltration, and endothelial cell dysfunction might be caused by a pathologic condition in COVID-19 patient lungs rather than a direct infection with SARS-CoV-2. FUNDING: This work was supported by the Johns Hopkins University, the American Heart Association, and the National Institutes of Health.

Risk of Intraocular Bleeding With Novel Oral Anticoagulants Compared With Warfarin: A Systematic Review and Meta-analysis.

Importance: It is unclear if the risk of intraocular bleeding with novel oral anticoagulants differs compared with warfarin. Objective: To characterize the risk of intraocular bleeding with novel oral anticoagulants compared with warfarin. Data Sources: A systematic review and meta-analysis was undertaken in an academic medical setting. MEDLINE and ClinicalTrials.gov were searched for randomized clinical trials published up until August 2016. This search was supplemented by manual bibliography searches of identified trials and other review articles. Study Selection: Studies were eligible for inclusion if they were phase 3 randomized clinical trials, enrolled patients with atrial fibrillation or venous thromboembolism, compared a novel oral anticoagulant (dabigatran, rivaroxaban, apixaban, or edoxaban) with warfarin, and recorded event data on intraocular bleeding. Data on intraocular bleeding were pooled using inverse-variance, weighted, fixed-effects meta-analysis. Data Extraction and Synthesis: The PRISMA guidelines were used for abstracting data and assessing quality. Independent extraction was performed by 2 investigators. Main Outcomes and Measures: Intraocular bleeding events and associated risk ratio for novel oral anticoagulants compared with warfarin. Results: Twelve trials investigating 102 627 patients were included. Randomization to novel oral anticoagulants was associated with a 22% relative reduction in intraocular bleeding compared with warfarin (risk ratio, 0.78; 95% CI, 0.61-0.99). There was no significant heterogeneity observed (I2 = 4.8%, P = .40). Comparably lower risks of intraocular bleeding with novel oral anticoagulants were seen in subgroup analyses, with no significant difference according to the indication for anticoagulation (P for heterogeneity = .49) or the novel oral anticoagulant type (P for heterogeneity = .15). Summary estimates did not differ materially when random-effects meta-analytic techniques were used. Conclusions and Relevance: These results suggest that novel oral anticoagulants reduce the risk of intraocular bleeding by approximately one-fifth compared with warfarin. Similar benefits were seen in both patients with atrial fibrillation and venous thromboembolism. Our data have particular relevance for patients at higher risk of spontaneous retinal and subretinal bleeding. These findings may also have important implications in the perioperative period, in which the use of novel oral anticoagulants may be superior. Future studies are required to better characterize the optimal management of patients with both ophthalmic disease and cardiovascular comorbidities requiring anticoagulation.