The Effect Of Blocking B7-H1/PD-1 Pathway On The Immune Effect Of BCG-induced Bladder Cancer In Rats

Objective:Bladder malignant tumor incidence first urogenital system in our country,with the characteristics of multi center,easy to relapse.For the prevention of postoperative recurrence of Bacillus Calmette-Guérin(BCG)in bladder cancer diagnosis and treatment guidelines of many countries are to be as high-risk non muscle invasive bladder cancer effective solution perfusion in the treatment of postoperative,however,there are still 30%of patients with bladder cancer recurrence in BCG immunotherapy.To investigate the mechanism of recurrence,we found that early treatment failure in BCG bladder cancer tissues B7-H1 expression and inhibition of costimulatory molecule B7-H1 as negative regulatory molecules expressed on tumor cells,binding to T receptors on the cell surface to suppress the immune function and mediated apoptosis so as to provide favorable conditions for tumor escape.The experimental study of BCG treatment of bladder tumor immune response process,by blocking the B7-H1/PD-1 pathway reduces the expression of bladder cancer cells B7-H1,to explore the feasibility of BCG immunotherapy and blocking B7-H1/PD-1 pathway immune therapy combined therapy of bladder cancer.Method:1 、 The rat orthotopic bladder cancer model was induced by N-methyl urea(MNU).After 10 weeks,CT was used to observe the tumor formation of bladder in rats by intravesical instillation of iodine contrast agent.2、The rats were randomly divided into B7-H1 antibody combined with BCG group,B7-H1 antibody group,BCG group and saline group.The application of B7-H1 antibody(Bio-XCell,10 F.9G2)200 g by intraperitoneal injection in antibody group,3 times / day * 4 times;BCG group received0.5 mg of BCG vaccine instillation,1 times / week * 4 times;Joint group of rats to repeat the above operation of 3 days / times * 4 times and 1 weeks / * 4 times;The normal saline group was given the same period of measurement of bladder perfusion and /or intraperitoneal injection.3、At the end of the 4 week,the bladder and bladder tumors were observed,and the number of Granzyme B was detected by immunohistochemistry after the rats were sacrificed and dissected.At the same time,the tumor tissue were made into single cell suspension,and the tumor infiltrating lymphocytes(tumor infiltrating lymphocyte,TIL)were isolated from a single cell suspension.To determine the immune response of B7-H1 blocking antibody combined with BCG in the treatment of bladder cancer,Flow cytometry was used to detect the number of CD8 and the number of MDSCs(CD11b+Gr1+).Result: 1 、 The experimental group of bladder tumor tissues was detected by immunohistochemical staining of granzyme B positive count,Joint group average of24.64,BCG group average of 19.88,the antibody group average of 14.25,saline group average of 9.13,the granzyme B positive count and the control group was statistically significant with immunotherapy combined in rat bladder cancer(p<0.05).2、Each group of bladder tumor cells were detected by flow cytometry of infiltrating lymphocytes CD8+expression rate,combined group average of 38.82% for the BCG group,antibody group and saline group were 21.92%,15.08%,12.44%,the expression rate of CD8+ group and the control group was statistically significant(p<0.05).3 、 Flow cytometry to detect bladder tumor infiltrating lymphocytes CD11 b expression and Gr1 positive rate of the combined group,the average value is 2.86%,the BCG group,antibody group and saline group were 3.51%,5.34%,12.02%,the expression rate of CD11b+Gr1+ group and the control group was statistically significant(p<0.05).Conclusion:BCG immunotherapy and blocking B7-H1/PD-1 pathway immune therapy,and further demonstrates the possible mechanism of BCG immune failure of bladder cancer immunotherapy with B7-H1 mediated escape mechanism;and can promote tumor cells in the microenvironment of immune cytotoxicity to tumor,enhance the immune effect of the body’s anti-tumor therapeutic effect stronger has certain feasibility;immunotherapy combined with bladder cancer,B7-H1 blocking antibody drugs can further promote the development of.