Inhibition of mouse SP2/0 myeloma cell growth by the B7-H4 protein vaccine

Co-immunizing with PD-L1 induces CD8+ DCs-mediated anti-tumor immunity in multiple myeloma

Tumor therapeutic vaccines have faced a challenge for effective protection against malignant tumors by inducing tumor-specific CD8⁺ T cell responses. Here, we designed a DNA vaccine containing a tumor-specific antigen of Dickkopf-1 (DKK-1) and an immune checkpoint of programmed death ligand 1 (PD-L1) delivered by PLGA/PEI nanoparticle-mediated delivery system for multiple myeloma therapy. Murine subcutaneous tumor model established with human DKK1 (hDKK-1)-SP2/0 cells were intramuscularly immunized with PLGA/PEI-pPD-L1/pDDK-1 vaccine and equal amount of control 3 times at 10 day-intervals. Compared with PLGA/PEI-pDKK1 immunization group, PLGA/PEI-pPD-L1/pDKK-1 co-immunization enhanced the induction and mature of CD11c⁺ DCs and CD8⁺CD11c⁺ DCs, and promoted antigen-specific Th1 responses and cytotoxic T lymphocyte (CTL) responses. The reduced tumor volume and weight as well as increased tumor inhibition rate were observed in PLGA/PEI-pPD-L1/pDKK-1 vaccine co-immunization group, indicated that the vaccine could effectively inhibit the tumor growth of multiple myeloma. The anti-tumor activity of PLGA/PEI-pPD-L1/pDKK-1 vaccine was abrogated by CD8 cell depletion accompanied with the reduced percentages of CD8⁺CD11c⁺ DCs and CD8⁺ T cells in the spleen and TILs. These results indicated that the anti-tumor efficacy of PLGA/PEI-pPD-L1/pDKK-1 vaccine was required for CD8⁺CD11c⁺ DCs-mediated CD8⁺ T cell immunity responses. This vaccine strategy may represent a potential and promising approach for hematological malignancy treatment.

Construction, expression and functional analysis of anti-B7-H4- scFv-CH3 recombinant antibody

The B7-H4 molecule, a unique negative regulator of T lymphocytes which is overexpressed on the surface of various tumor cells, is a particularly important target candidate for tumor therapy because it can be blocked with anti-B7-H4 antibodies to inhibit the B7-H4 signaling pathway. Our previous work established an anti-B7-H4 single-chain variable fragment (scFv) library, so we have now amplified the genes encoding anti-B7-H4-scFv and human IgG1 CH3 and ligated them by overlap extension PCR to obtain a recombinant gene. After sequencing, the gene was cloned into the expression vector pET43.1a and expression was induced in E. coli BL21 (DE3) by isopropyl-β-D-1-thiogalactopyranoside (IPTG). The protein was purified on a nickel-nitrilotriacetic acid (Ni-NTA) resin column and its antigen specificity and affinity were examined by ELISA and western blotting. We also established a Lewis lung cancer model in C57BL/6 mice to further identify the biological function of the scFv protein in vivo. The results showed that tumor volume, body weight and necrotic tissues in the control group were significantly greater than in the experimental group, indicating that selected scFvs had good biological activity and could inhibit tumor growth in tumor-bearing mice. Our work thus offers a new approach for the development of cancer-targeted therapy.

Immunosuppressive Effect of B7-H4 Pathway in a Murine Systemic Lupus Erythematosus Model

B7-H4, one of the co-stimulatory molecules of the B7 family, has been shown to play an important role in negatively regulating the adaptive immune response by inhibiting the proliferation, activation, and cytokine production of T cells. In this study, we investigate the role of B7-H4 in development of systemic lupus erythematosus (SLE). We investigated a murine model of SLE using transfer of bone marrow-derived dendritic cells (BMDCs) that were incubated with activated syngeneic lymphocyte-derived DNA. The recipient mouse produced anti-ds-DNA antibodies as well as displayed splenomegaly and lymphadenopathy as shown by significantly increased weights, and the kidneys showed lupus-like pathological changes include urine protein and glomerulonephritis with hyperplasia in glomeruli and increased mesangial cells and vasculitis with perivascular cell infiltration, glomerular deposition of IgG and complement C3. We showed that B7-H4 deficiency in BMDCs could cause greater production of anti-ds-DNA antibodies in transferred mice, and the lymph tissue swelling and the kidney lesions were also exacerbated with B7-H4 deficiency. Treatment with a B7-H4 antagonist antibody also aggravated the lupus model. Conversely, B7-H4 Ig alleviated the lupus manifestations. Therefore, we conclude that B7-H4 is a negative check point for the development of SLE in this murine model. These results suggest that this approach may have a clinical potential in treating human SLE.