Resident memory T cells in mouse and human

Mechanism of Sishen-Pill-Regulated Special Memory T and mTfh Cell via Involving JAK/STAT5 Pathway in Colitis Mice

It is known that memory T cells (mT cell) and memory T follicular cells (mTfh) play vital roles in the IBD pathogenesis. Sishen Pill (SSP) is a classic prescription used to treat chronic ulcerative colitis (UC). However, it is still unclear whether SSP can regulate immune homeostasis induced by mT cell and mTfh to treat IBD. In this study, we measured mT cell and mTfh level to explore the conceivable mechanism of SSP-treated IBD. The mice colitis were induced by dextran sulfate sodium (DSS) and were treated by SSP for 7 days. The therapeutic effect of SSP was evaluated by macroscopic and microscopic observation; the mT cell, mTfh, and their subsets were analyzed by flow cytometry. Activation of the JAK/STAT signaling pathway was analyzed by using a Western blot. In the present study, SSP significantly reversed weight loss and colonic injury (colon weight increase and colonic length shortening) caused by 3% DSS in physiological saline solution. Flow cytometry showed that the percentages of CD4+ and CD8+ expressions on central memory T cells were enhanced after SSP treatment, while the CD4+ T cm, CD4+ mTfh (memory T follicular helper) cells and their subpopulations were also significantly increased. Moreover, SSP inhibited the expression of JAK/STAT signaling pathway proteins JAK1, PIAS3, STAT5, p-STAT5, BIM, BAX, caspase-3, and β-casein and promoted the expression of JAK3, PISA1, Bcl-2, and caveolin-1. In summary, SSP can regulate immune homeostasis induced by mT cell and mTfh in DSS-induced colitis, which is potentially correlated with JAK/STAT signaling pathway activation.

Memory T Cells in Pregnancy

Adaptations of the maternal immune response are necessary for pregnancy success. Insufficient immune adaption is associated with pregnancy pathologies such as infertility, recurrent miscarriage, fetal growth restriction, spontaneous preterm birth, and preeclampsia. The maternal immune system is continuously exposed to paternal-fetal antigens; through semen exposure from before pregnancy, through fetal cell exposure in pregnancy, and through microchimerism after pregnancy. This results in the generation of paternal-fetal antigen specific memory T cells. Memory T cells have the ability to remember previously encountered antigens to elicit a quicker, more substantial and focused immune response upon antigen reencounter. Such fetal antigen specific memory T cells could be unfavorable in pregnancy as they could potentially drive fetal rejection. However, knowledge on memory T cells in pregnancy has shown that these cells might play a favorable role in fetal-maternal tolerance rather than rejection of the fetus. In recent years, various aspects of immunologic memory in pregnancy have been elucidated and the relevance and working mechanisms of paternal-fetal antigen specific memory T cells in pregnancy have been evaluated. The data indicate that a delicate balance of memory T cells seems necessary for reproductive success and that immunologic memory in reproduction might not be harmful for pregnancy. This review provides an overview of the different memory T cell subtypes and their function in the physiology and in complications of pregnancy. Current findings in the field and possible therapeutic targets are discussed. The findings of our review raise new research questions for further studies regarding the role of memory T cells in immune-associated pregnancy complications. These studies are needed for the identification of possible targets related to memory mechanisms for studies on preventive therapies.