Long-term efficacy and influencing factors of extended thymectomy for myasthenia gravis with thymic atrophy / 中国胸心血管外科临床杂志

@#Objective    To analyze the surgical efficacy and influencing factors of myasthenia gravis (MG) patients with thymic atrophy after thymectomy. Methods    The clinical data of MG patients with thymic atrophy undergoing thymectomy between October 2014 and May 2018 in Daping Hospital of Army Medical University and Shijiazhuang People Hospital were retrospectively analyzed. Results    A total of 71 patients were collected, including 40 males and 31 females with a mean age of 45.17±12.42 years. All patients received the surgery successfully. After the surgery, 20 (28.17%) patients were stable remission, 12 (16.90%) patients were minimal manifestation status,19 (26.76%) patients were improved, 5 (7.04%) patients showed no change, 3 (4.23%) patients were worsened, 10 (14.08%) patients were exacerbated and 2 (2.82%) patients were dead. Multivariate logistic regression analysis showed that the preoperative illness duration (OR=4.61, 95%CI 1.13-18.85, P=0.03), and postoperative pyridostigmine combined with immunosuppressive (OR=0.12, 95%CI 0.03-0.45, P=0.00) were independent risk factors for long-term efficacy of thymectomy for MG patients with thymic atrophy. Conclusion    Early surgery after diagnosis of MG and postoperative pyridostigmine combined with immunosuppressive treatment is beneficial to the prognosis of MG patients with thymic atrophy.

CRISPR/Cas9-mediated knockout of Rag-2 causes systemic lymphopenia with hypoplastic lymphoid organs in FVB mice / 한국실험동물학회지

Recombination activating gene-2 (RAG-2) plays a crucial role in the development of lymphocytes by mediating recombination of T cell receptors and immunoglobulins, and loss of RAG-2 causes severe combined immunodeficiency (SCID) in humans. RAG-2 knockout mice created using homologous recombination in ES cells have served as a valuable immunodeficient platform, but concerns have persisted on the specificity of RAG-2-related phenotypes in these animals due to the limitations associated with the genome engineering method used. To precisely investigate the function of RAG-2, we recently established a new RAG-2 knockout FVB mouse line (RAG-2(−/−)) manifesting lymphopenia by employing a CRISPR/Cas9 system at Center for Mouse Models of Human Disease. In this study, we further characterized their phenotypes focusing on histopathological analysis of lymphoid organs. RAG-2(−/−) mice showed no abnormality in development compared to their WT littermates for 26 weeks. At necropsy, gross examination revealed significantly smaller spleens and thymuses in RAG-2(−/−) mice, while histopathological investigation revealed hypoplastic white pulps with intact red pulps in the spleen, severe atrophy of the thymic cortex and disappearance of follicles in lymph nodes. However, no perceivable change was observed in the bone marrow. Moreover, our analyses showed a specific reduction of lymphocytes with a complete loss of mature T cells and B cells in the lymphoid organs, while natural killer cells and splenic megakaryocytes were increased in RAG-2(−/−) mice. These findings indicate that our RAG-2(−/−) mice show systemic lymphopenia with the relevant histopathological changes in the lymphoid organs, suggesting them as an improved Rag-2-related immunodeficient model.

Comparison of polycytidylic acid-induced and dexamethasone-induced thymic atrophy and their thymic expression of RIG-Ⅰ like receptors signaling pathway / 中国免疫学杂志

Objective:To provide experimental evidences for choosing murine models in the pathogenesis research of thymic impairment induced by viral infection,we compared the impacts of polycytidylic acid(Poly(I:C)) and dexamethasone(DEX) on the thymic morphology and thymic output function,and explored the implication of RLR signaling pathway.Methods: 24 male C57BL/6 mice were randomly assigned into three groups and treated with Poly(I:C),DEX,or saline respectively.Thereafter,their thymic morphology,pathological changes,thymic index,and thymic pathology were examined.Their contents of T-cell receptor excision circles (TRECs) and proportions of the naive CD4+T cell in the peripheral blood were determined to evaluate their thymic output function.The expression levels of thymic RLR/MAVS/IFN-α/β signaling pathway and IL-1β were also measured.Results: Both Poly (I:C) and DEX treatment caused thymic atrophy in appearance and structural destruction under the microscope inspection,and DEX treatment did much more severe damage,especially to the thymic cortex.TRECs decreased significantly in both groups.The proportions of na?ve/memory CD4+T cell subsets remained stable,though total CD4+T cell decreased in DEX group,while the proportion of na?ve CD4+T cell in Poly (I:C) group increased significantly.The expression of RIG-Ⅰ,MDA5,LGP2,and IFN-α/β were up-regulated in DEX group, while it remained unchanged in Poly (I:C) group.Conclusion:Both Poly (I:C) and DEX induced thymic atrophy and the impaired thymic output function.Nevertheless,the expression of RLR-IFN signaling pathway up-regulated more significantly in DEX group instead of in Poly (I:C) group.These results implied the existence of different pathological manifestations and mechanisms underlying the impaired thymic function in different animal models,as well as impact on na?ve/memory CD4+T cell proportions.Our research provides references for choosing animal models in the basic research and drug development for viral infection induced thymic atrophy based on the RLR signaling pathway.

The Anti-apoptotic Effect of Ghrelin on Restraint Stress-Induced Thymus Atrophy in Mice

Thymic atrophy is a complication that results from exposure to many environmental stressors, disease treatments, and microbial challenges. Such acute stress-associated thymic loss can have a dramatic impact on the host's ability to replenish the necessary naïve T cell output to reconstitute the peripheral T cell numbers and repertoire to respond to new antigenic challenges. We have previously reported that treatment with the orexigenic hormone ghrelin results in an increase in the number and proliferation of thymocytes after dexamethasone challenge, suggesting a role for ghrelin in restraint stress-induced thymic involution and cell apoptosis and its potential use as a thymostimulatory agent. In an effort to understand how ghrelin suppresses thymic T cell apoptosis, we have examined the various signaling pathways induced by receptor-specific ghrelin stimulation using a restraint stress mouse model. In this model, stress-induced apoptosis in thymocytes was effectively blocked by ghrelin. Western blot analysis demonstrated that ghrelin prevents the cleavage of pro-apoptotic proteins such as Bim, Caspase-3, and PARP. In addition, ghrelin stimulation activates the Akt and Mitogen-activated protein kinases (MAPK) signaling pathways in a time/dose-dependent manner. Moreover, we also revealed the involvement of the FoxO3a pathway in the phosphorylation of Akt and ERK1/2. Together, these findings suggest that ghrelin inhibits apoptosis by modulating the stress-induced apoptotic signal pathway in the restraint-induced thymic apoptosis.