Beneficial Effect Of T Follicular Helper Cells On Antibody Class Switching Of B Cells In Prostate Cancer

Backgrouds:In recent years, people’s diet structure and lifestyle have changed a lot with the development of society. The morbidity of prostate cancer(PCa) has an obvious increase. Androgen deprivation therapy is an efficient treatment for PCa, and it has been a standard treatment for prostate cancer together with surgical operation and radiotherapy. However, though this therapeutic schedule opposes a 70% response rate in the early prostatic cancer, it’ll typically progresses to castrate-resistant prostate cancer(CRPC) after the remission stage with the feature of high proliferation of PCa cells, combining with an increased PSA level and prostate cancer bone metastasis, which makes the treatment more difficult, leading to a extremely high mortality rate. Thus, with the PCa development, the existing standard first-line treatments face a serious limitation, and exploring an effective treatment towards AIPC becomes a difficult problem we need to resolve.The process of carcinogenesis, development and metastasis is influenced by various factors. The microenvironment of cancer cell is also closely related with this process, which including not only the tumor tissue structure, physiological function and metabolism, but also the other tissue and cells, especially the distribution and status of immune cells.In recent years, with the development of immunology, the change of immune environment, especially the relationship between chronic inflammation and PCa development has became a focus of research. Studies have found the pre-inflammatory factor IL-8 could be expressed highly in PCa cells, which led to a continually activation of NF-κB that associated with drug resistance.B cell plays a very important regulatory effect in the immune response. B cells can act as antigen presenting cells. It was able to capture antigens, process the antigen into peptides and then present them to T cells, mediating specific immune response. Meanwhile, B cells can secret a variety of immune related cytokines, chemokines, and express membrane proteins, modulating immune responses from many aspects. Recent studies have showed there existed a new member of Th subtypes—T follicular helper cells(TFH) that locates in lymphoid follicle. TFH cells express CXCR5, which can facilitate the recruitment of TFH to lymphoid follicle through a CXCR5 specific ligand CXCL13. TFH cells mediate humoral immune response through modulating the B cell differentiation and maturity via expressing ICOS, PD-1 and secreting IL-21. Therefore, the investigates of the subsets of B cells and B-cell-related TFH cells, especially the distribution and differential functions of TFH subsets are essential to reveal the roles of B cells and TFH cells in regulating B cells, supplying the experimental theory and a new direction for the efficient immune therapy of PCa.Obiective:To study the expression and the potential mechanism of B cells and TFH subsets in peripheral blood of PCa patients at different disease stage, and explore the related function and modulation of these different T- and B-cell subsets in the PCa development, providing a new way for the immunotherapy-based therapy. Method:30 primary PCa patients diagnosed by Digital Rectal Examination(DER), biopsy and Prostate specific antigen(PSA) were collected from China–Japan union hospital, and divided into group A(≤ T1), group B(T2) and group C(≥ T3) according to the PCa clinical staging criteria. 10 healthy cases were selected as control group(healthy control, HC). The distributions of na?ve B cells, memory B cells, mature B cells and TFH subsets(TFH1、TFH2、TFH17) were detected by flow cytometry in patients and healthy controls. The ratio of Ig G1, Ig G2, Ig G3 and Ig G4 in total Ig G, as well as the level of IL-4, IL-6, IL-10 and PGE2 were tested by enzyme linked immunosorbent assay(ELISA) respectively. The expression changes of CXCR3 and CCR6 in both transcription and translation level were evaluated by reverse transcriptase polymerase chain reaction(RT-PCR) and western blot. Results:The frequencies of memory B cells gradually dropped in the peripheral blood of patients with the PCa development, and that of the mature B cells was significantly up-regulated in group C, while that of na?ve B cells raised a little in all three groups but the level changes had no statistical significance. The ratio of Ig G4/total Ig G was gradually increased in group B and group C. The frequencies of TFH2 was increased in the peripheral blood mononuclear cell(PBMC) of PCa patients, while that of TFH1 and TFH17 didn’t change evidently and showed no relationship with the PCa development. We found TFH2 could induce the high ratio of Ig G4/total Ig G in the co-culture system of B cells with different TFH subsets. Meanwhile, the ratio of Ig G4/total Ig G was also found to be up-regulated with the stimulation of IL-4, IL-6, IL-10 and PGE2 in the co-culture system of B cells with total TFH cells, accompanying with the increased TFH2 cells, and this process was able to be suppressed by anti-IL-21 antibody. Conclusion:The level of mature B cells and its secreting Ig G4 was gradually increased in patients’ PBMCs with the PCa development. The abnormal differentiation of B cells might be caused by the raised frequency of TFH2 subset. Further studies focused on the abnormal distribution of TFH subsets and its influence on the B cell proliferation and differentiation will provide new insight and direction for the effective treatment that targeted TFH cells.