Search

Mucosal-associated invariant T (MAIT) cells are a subset of T lymphocytes that respond to microbial metabolites. We defined MAIT cell populations in different organs and characterized the developmental pathway of mouse and human MAIT cells in the thymus using single-cell RNA sequencing and phenotypic and metabolic analyses. We showed that the predominant mouse subset, which produced IL-17 (MAIT17), and the subset that produced IFN-γ (MAIT1) had not only greatly different transcriptomes but also different metabolic states. MAIT17 cells in different organs exhibited increased lipid uptake, lipid storage, and mitochondrial potential compared with MAIT1 cells. All these properties were similar in the thymus and likely acquired there. Human MAIT cells in lung and blood were more homogeneous but still differed between tissues. Human MAIT cells had increased fatty acid uptake and lipid storage in blood and lung, similar to human CD8 T resident memory cells, but unlike mouse MAIT17 cells, they lacked increased mitochondrial potential. Although mouse and human MAIT cell transcriptomes showed similarities for immature cells in the thymus, they diverged more strikingly in the periphery. Analysis of pet store mice demonstrated decreased lung MAIT17 cells in these so-called "dirty" mice, indicative of an environmental influence on MAIT cell subsets and function.

Background: Head injuries are an important cause of morbidity and mortality in children and young adults. There are multiple sight-threatening complications of head injury, even in closed head injury without visible violation of the globe or orbits. One such entity is traumatic optic neuropathy., Case Report: Herein we describe a case of traumatic optic neuropathy in an otherwise healthy teenage patient who suffered total monocular vision loss after a fall and without any other injuries on examination. Unfortunately, the prognosis for this condition is relatively poor in terms of visual recovery. Though much research has been conducted attempting to treat this condition, to date there have been no studies showing a clear benefit of medical or surgical intervention. Why Should an Emergency Physician Be Aware of This? Although there is no proven treatment for traumatic optic neuropathy, emergency physicians may encounter this in their practice while caring for both pediatric and adult patients presenting with head injury. Having more background knowledge on this condition will enhance emergency physicians' ability to consult with subspecialist providers as well as to educate patients and their families on their condition and prognosis., (Copyright © 2021. Published by Elsevier Inc.)

Aims: Here we explore the presence of mediator complex subunit 12 ( MED12 ) exon 2 and telomerase reverse transcriptase ( TERT ) promoter hotspot mutations in complex fibroadenomas (CFAs) of the breast., Methods: The stromal components from 18 CFAs were subjected to Sanger sequencing of MED12 exon 2 and the TERT promoter hotspot loci. The epithelial and stromal components of two MED12 mutated CFAs were subjected to laser capture microdissection, and Sanger sequencing of MED12 exon 2, TERT promoter and PIK3CA exons 9 and 20, separately., Results: MED12 exon 2 mutations were identified in the stroma of 17% of CFAs. The analyses of epithelial and stromal components, microdissected separately, revealed that MED12 mutations were restricted to the stroma. No TERT promoter or PIK3CA mutations in exons 9 and 20 were detected in analysed CFAs., Conclusions: Like conventional fibroadenomas, MED12 exon 2 mutations appear to be restricted to the stromal component of CFAs, supporting the notion that CFAs are stromal neoplasms., Competing Interests: Competing interests: JSR-F reports receiving personal/consultancy fees from Goldman Sachs and REPARE Therapeutics, membership of the scientific advisory boards of VolitionRx, REPARE Therapeutics and Paige. AI, membership of the Board of Directors of Grupo Oncoclinicas, and ad hoc membership of the scientific advisory boards of Roche Tissue Diagnostics, Ventana Medical Systems, Novartis, Genentech and InVicro, outside the scope of this study. HZ reports consultancy fee from Roche/Genentech, outside the scope of the submitted work. FB is currently an employee and equity holder of Seattle Genetics, Inc but the present work is outside the scope of his role., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Innate-like T cells, including invariant natural killer T cells, mucosal-associated invariant T cells, and γδ T cells, are present in various barrier tissues, including the lung, where they carry out protective responses during infections. Here, we investigate their roles during pulmonary pneumococcal infection. Following infection, innate-like T cells rapidly increase in lung tissue, in part through recruitment, but T cell antigen receptor activation and cytokine production occur mostly in interleukin-17-producing NKT17 and γδ T cells. NKT17 cells are preferentially located within lung tissue prior to infection, as are CD103 + dendritic cells, which are important both for antigen presentation to NKT17 cells and γδ T cell activation. Whereas interleukin-17-producing γδ T cells are numerous, granulocyte-macrophage colony-stimulating factor is exclusive to NKT17 cells and is required for optimal protection. These studies demonstrate how particular cellular interactions and responses of functional subsets of innate-like T cells contribute to protection from pathogenic lung infection., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)