Secretion of immunoregulatory cytokines by mesenchymal stem cells

According to the minimal criteria of the International Society of Cellular Therapy, mesenchymal stem cells(MSCs) are a population of undifferentiated cells defined by their ability to adhere to plastic surfaces when cultured under standard conditions, express a certain panel of phenotypic markers and can differentiate into osteogenic, chondrogenic and adipogenic lineages when cultured in specific inducing media. In parallel with their major role as undifferentiated cell reserves, MSCs have immunomodulatory functions which are exerted by direct cell-to-cell contacts, secretion of cytokines and/or by a combination of both mechanisms. There are no convincing data about a principal difference in the profile of cytokines secreted by MSCs isolated from different tissue sources, although some papers report some quantitative but not qualitative differences in cytokine secretion. The present review focuses on the basic cytokines secreted by MSCs as described in the literature by which the MSCs exert immunodulatory effects. It should be pointed out that MSCs themselves are objects of cytokine regulation. Hypothetical mechanisms by which the MSCs exert their immunoregulatory effects are also discussed in this review. These mechanisms may either influence the target immune cells directly or indirectly by affecting the activities of predominantly dendritic cells. Chemokines are also discussed as participants in this process by recruiting cells of the immune systems and thus making them targets of immunosuppression. This review aims to present and discuss the published data and the personal experience of the authors regarding cytokines secreted by MSCs and their effects on the cells of the immune system.

附睾降解性不活动精子症的研究

目的 :探讨精子不活动是否由附睾降解引起。方法 :本文选择 5例精液中无活动精子的不育患者 ,应用睾丸精子活力检测、精子头 -尾膜完整性结合试验和透射电镜观察 ,探讨其精子不活动的原因。结果 :5例患者睾丸活检组织所分离的睾丸精子 ,经孵育后的活动率为 2 %～ 1 1 %。睾丸精子组中头膜 -尾膜均完整的精子率显著高于射出精子组 ( P<0 .0 1 )。睾丸精子未见明显的降解 ,但透射电镜显示射出精子的浆膜、核等结构表现显著的降解变化。结论 :本组患者的精子可能经历了病理性附睾降解 ,引致精子丧失活动性 ,对这类患者采用活动的睾丸精子作辅助生育治疗有可能改善成功率。

Human Sperm Immotility Caused by Degeneration in the Epididymis

Objective To investigate whether sperm immotility was caused by degeneration in the epididymis Methods Five patients with totally immotile sperm were selected in this study. Testicular biopsy was used to obtain testicular sperm to evaluate sperm motility. The combined hypoosmotic swelling eosin Y exclusion test was carried out to determine the sperm head and tail membrane integrity for the ejaculated and the testicular sperm. The ultrastructure of ejaculated sperm was examined by transmission electron microscope. Results No motile sperm were found in the ejaculated semen samples from 5 patients, whereas 2% to 11% motile testicular sperm extracted from the testicular biopsy tissues were observed. The percentage of testicular sperm with intact head and tail membranes was higher than that of the ejaculated sperm (P<0.01). Ultrastructure of the ejaculated sperm showed marked degenerative features. Seminal plasma from patients did not influence the motility of normal donor sperm. Conclusion Sperm could undergo degenerative changes during transit through and /or storage in the epididymis, which led to lose sperm motility in these patients. Using motile testicular sperm would benefit the treatment for such cases.

SARS-CoV-2 spike-specific TFH cells exhibit unique responses in infected and vaccinated individuals

Long-term humoral immunity to SARS-CoV-2 is essential for preventing reinfection. The production of neutralizing antibody (nAb)and B cell differentiation are tightly regulated by T follicular help (T_(FH)) cells. However, the longevity and functional role of T_(FH) cellsubsets in COVID-19 convalescents and vaccine recipients remain poorly defined. Here, we show that SARS-CoV-2 infection andinactivated vaccine elicited both spike-specific CXCR3^(+) T_(FH) cell and CXCR3^(-) T_(FH) cell responses, which showed distinct responsepatterns. Spike- specific CXCR3^(+) T_(FH) cells exhibit a dominant and more durable response than CXCR3^(-) T_(FH) cells that positivelycorrelated with antibody responses. A third booster dose preferentially expands the spike-specific CXCR3^(+) T_(FH) cell subset inducedby two doses of inactivated vaccine, contributing to antibody maturation and potency. Functionally, spike-specific CXCR3^(+) T_(FH) cellshave a greater ability to induce spike-specific antibody secreting cells (ASCs) differentiation compared to spike-specific CXCR3^(-) T_(FH)cells. In conclusion, the persistent and functional role of spike-specific CXCR3^(+) T_(FH) cells following SARS-CoV-2 infection andvaccination may play an important role in antibody maintenance and recall response, thereby conferring long-term protection. Thefindings from this study will inform the development of SARS-CoV-2 vaccines aiming to induce long-term protective immunememory.