Tim3scFv-Transforming Lactobacillus Inhibits Transplanted Tumor of Renal-Cell Carcinoma.

INTRODUCTION:T-cell immunoglobulin-3 (Tim-3) antibody drugs can treat malignant renal tumors but are expensive. To overcome this limitation, Lactococcus lactis host bacteria were used to express Tim-3 single-chain antibodies.METHODS:The pLAN-CTB-Tim3scFv plasmid was constructed using molecular cloning technology and transformed into Lactococcus lactis. Expression and immune activity of proteins in the transformed bacteria were analyzed using Western blotting and enzyme-linked immunosorbent assay in vitro. A mouse subcutaneously transplanted tumor model of renal adenocarcinoma was constructed. The promoting effect of transformed bacteria on mouse spleen lymphocyte activation and their inhibitory effect on transplanted tumors were analyzed.RESULTS:Transformed L. lactis NZ-CTB-Tim3scFv and NZ-Tim3scFv were successfully constructed. CTB-Tim3scFv secreted by NZ-CTB-Tim3scFv showed immunological activity. Compared with the NZ-Tim3scFv and NZ-Vector groups, the subgroups of splenic lymphocytes in the NZ-CTB-Tim3scFv group had a higher proportion of CD3+CD4+, CD3+CD8a+, and CD3+CD69+ cells. Ki67 and CD31 expression in the NZ-CTB-Tim3scFv group was significantly reduced. Tumor volume in the NZ-CTB-Tim3scFv group increased the least.DISCUSSION/CONCLUSION:Secretion of CTB-Tim3scFv promoted the proliferation and activation of spleen lymphocytes and inhibited growth, cell proliferation, and angiogenesis of tumors. The proposed method is low cost and convenient with potential to become a new immunotherapy approach for renal-cell carcinoma.