Viral infection in thymoma and thymic tumors with autoimmune diseases

Type B3 thymoma complicated with Chlamydia psittaci pneumonia with rare features: A case report

The case of a patient with type B3 thymomacomorbid with Chlamydia psittaci (C. psittaci) pneumonia exhibiting rare features is presented in the current report. The patient was admitted at the Second Affiliated Hospital of Jiaxing University (Jiaxing, China) with a history of direct contact with poultry. Clinical manifestations included fever, shivers, cough, fatigue and poor appetite. Chest computed tomography (CT) indicated right lung pneumonia, while metagenomics next-generation sequencing using bronchoalveolar lavage fluid confirmed infection with C. psittaci. Additionally, positron emission tomography-CT suggested the presence of thymoma. After surgery and treatment with doxycycline and imipenem cilastatin, the patient was discharged showing signs of improvement.

Thymic Epithelial Tumor and Immune System: The Role of Immunotherapy

Thymic epithelial tumors (TETs) comprise a rare group of thoracic cancers, classified as thymomas and thymic carcinomas (TC). To date, chemotherapy is still the standard treatment for advanced disease. Unfortunately, few therapeutic options are available for relapsed/refractory tumors. Unlike other solid cancers, the development of targeted biologic and/or immunologic therapies in TETs remains in its nascent stages. Moreover, since the thymus plays a key role in the development of immune tolerance, thymic tumors have a unique biology, which can confer susceptibility to autoimmune diseases and ultimately influence the risk-benefit balance of immunotherapy, especially for patients with thymoma. Indeed, early results from single-arm studies have shown interesting clinical activity, albeit at a cost of a higher incidence of immune-related side effects. The lack of knowledge of the immune mechanisms associated with TETs and the absence of biomarkers predictive of response or toxicity to immunotherapy risk limiting the evolution of immunotherapeutic strategies for managing these rare tumors. The aim of this review is to summarize the existing literature about the thymus's immune biology and its association with autoimmune paraneoplastic diseases, as well as the results of the available studies with immune checkpoint inhibitors and cancer vaccines.

COVID-19-associated AMPA-R and CRMP-5 autoimmune encephalitis in a patient with thymoma and myasthenia gravis

Thymomas are associated with autoimmune disease, most commonly myasthenia gravis, and rarely with autoimmune encephalitis. More recently, viral triggers including COVID-19 have also been implicated in autoimmunity. We present a case of antibody-positive autoimmune encephalitis that developed in the setting of COVID-19 in a patient with thymomatous myasthenia gravis.

Herpesvirus entry mediator on T cells as a protective factor for myasthenia gravis: A Mendelian randomization study

Background and objectives

Myasthenia gravis (MG) is a T cell-driven, autoantibody-mediated disorder affecting transmission in neuromuscular junctions. The associations between the peripheral T cells and MG have been extensively studied. However, they are mainly of observational nature, thus limiting our understanding of the effect of inflammatory biomarkers on MG risk. With large data sets now available, we used Mendelian randomization (MR) analysis to investigate whether the biomarkers on T cells are causally associated with MG and further validate the relationships.

Methods

We performed a two-sample MR analysis using genetic data from one genome-wide association study (GWAS) for 210 extensive T-cell traits in 3,757 general population individuals and the largest GWAS for MG currently available (1,873 patients versus 36,370 age/gender-matched controls) from US and Italy. Then the biomarkers of interest were validated separately in two GWASs for MG in FIN biobank (232 patients versus 217,056 controls) and UK biobank (152 patients versus 386,631 controls).

Results

In the first analysis, three T-cell traits were identified to be causally protective for MG risk: 1) CD8 on terminally differentiated CD8⁺ T cells (OR [95% CI] = 0.71 [0.59, 0.86], P = 5.62e-04, adjusted P =2.81e-02); 2) CD4⁺ regulatory T proportion in T cells (OR [95% CI] = 0.44 [0.26, 0.72], P = 1.30e-03, adjusted P =2.81e-02); 3) HVEM expression on total T cells (OR [95% CI] = 0.67 [0.52, 0.86], P = 1.61e-03, adjusted P =2.81e-02) and other eight T-cell subtypes (e.g., naïve CD4+ T cells). In particular, HVEM is a novel immune checkpoint on T cells that has never been linked to MG before. The SNPs on the TNFRSF14 per se further support a more direct link between the HVEM and MG. The validation analysis replicated these results in both FIN and UK biobanks. Both datasets showed a concordant protective trend supporting the findings, albeit not significant.

Conclusion

This study highlighted the role of HVEM on T cells as a novel molecular-modified factor for MG risk and validated the causality between T cells and MG. These findings may advance our understanding of MG's immunopathology and facilitate the future development of predictive disease-relevant biomarkers.

Viral infection in thymoma and thymic tumors with autoimmune diseases

A thymoma is a type of thymic tumor which is rarely malignant that is frequently reported in adult patients. A number of thymoma-related immune disorders are observed including autoimmune diseases, which suggests a strong connection between thymoma development and immunological mechanisms. Characterized by association with humoral and cellular immunodeficiency, thymoma patients are susceptible to opportunistic infections by environmental factors. Recent reports have suggested that viral infection may play a role in the etiological mechanisms of thymoma development associated with dysregulated immunity. In this review, we summarize the case reports and studies related to viral infection, such as CMV, EBV and HSV, that probably play a part in the pathogenesis of thymoma and related diseases. Furthermore, we demonstrate the underlying mechanisms by which viruses may induce the occurrence of thymoma with autoimmune diseases. Lastly, we discuss the potential application of antiviral therapy in the treatment of thymic diseases.