Abstract
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.
