Recombinant attenuated Salmonella harboring 4-1BB ligand gene enhances cellular immunity

Efficacy of bivalent CEACAM6/4-1BBL genetic vaccine combined with anti-PD1 antibody in MC38 tumor model of mice

We used mouse CRC cell line (MC38) to establish a heterotopic mouse model, and applied [⁸⁹Zr]-labeled PD-L1 antibody KN035 for PET imaging. Attenuated Salmonella typhimurium 3261 was used as an anti-tumor vaccine, and the combined anti-tumor immunotherapy with bivalent genetic vaccine and anti-PD1 antibody Nivolumab was conducted. MicroPET was performed to observe the changes of tumor tissues and expression of PD-L1. We found that the recombinant double-gene plasmids were stably expressed in COS7 cells. Study results showed the combined immunotherapy improved the effectiveness over genetic vaccine alone. This study supports that combination of genetic vaccines and anti-immunocheckpoint immunotherapy can inhibit MC38 tumor growth.

TNFSF9 Is a Prognostic Biomarker and Correlated with Immune Infiltrates in Pancreatic Cancer

BACKGROUND

TNFSF9 gene has been found to play an anti-tumor role and regulate the function of immune cells. However, the prognostic role of TNFSF9 in pancreatic cancer and its relationship with immune cell infiltration have not been studied.

METHODS

We used Oncomine, UALCAN, and GEPIA databases to analyze the expression of TNFSF9 in pancreatic cancer. We used Kaplan-Meier plotters, GEPIA, and UALCAN to evaluate the effect of TNFSF9 on clinical prognosis. We further used TIMER to study the correlation between TNFSF9 and cancer immune infiltrate cells. In addition, we used GEPIA to analyze the correlation between TNFSF9 expression and gene markers of immune infiltrate cells.

RESULTS

TNFSF9 mRNA expression level was remarkably increased in pancreatic cancer than that in normal tissues (both P < 0.05). In addition, high TNFSF9 expression was significantly related to poor overall survival (OS) and relapse-free survival (RFS) in pancreatic cancer (OS HR = 2.02, P = 0.0012; RFS HR = 2.63, P = 0.022). Moreover, high TNFSF9 expression in pancreatic cancer patients was associated with worse OS in stage 1 to 2 but not stage 3 and stage 4. Specifically, TNFSF9 expression and CD8⁺ T cell infiltration of pancreatic cancer was negatively correlated. TNFSF9 expression showed strong correlations with M1 macrophages in pancreatic cancer.

CONCLUSIONS

Our results suggest that TNFSF9 is associated with prognosis and CD8⁺ T cell infiltration levels in patients with pancreatic cancer. Further, TNFSF9 expression potentially contributes to the modulation of M1 polarization of macrophages. These findings indicate that TNFSF9 can be serves as a prognostic biomarker in determining the prognosis of pancreatic cancer and is associated with different types of phenotypes of immune cell infiltration.

Recombinant Salmonella-based CEACAM6 and 4-1BBL vaccine enhances T-cell immunity and inhibits the development of colorectal cancer in rats: In vivo effects of vaccine containing 4-1BBL and CEACAM6

The present study aimed to determine the effect of recombinant Salmonella (SL3261)-based CEACAM6 and 4-1BB ligand (4-1BBL) vaccine on the development of colorectal cancer in rats and the potential immune mechanisms involved. Attenuated Salmonella typhimurium (vaccine strain)‑carrying plasmids pIRES-CEACAM6, pIRES‑4‑1BBL and pIRES-CEACAM6-4-1BBL were constructed. The rats were administered subcutaneous injections of 1,2-dimethyl-hydrazine (DMH) once a week for 18 weeks. Eight weeks after the first injection, the rats were divided into the pIRES/SL3261, pIRES-4-1BBL/SL3261, pIRES-CEACAM6/SL3261 and pIRES-CEACAM6-4-1BBL/SL3261 groups, and fed with corresponding vaccine strains. The rats were then sacrificed, the number of colon tumors were recorded, and the Dukes' stage were evaluated. CD3, CD4, CD8, CD56, FOXP3 and CEACAM6 expression in tumor tissues was determined by immunohistochemical staining. Compared with the expression levels in the pIRES/SL3261 group, similar levels of CD3+, CD8+ and CD56+ expression were identified for the pIRES-CEACAM6/SL3261 group of rats. Additionally, a comparable number of tumors was detected in the pIRES-4-1BBL/SL3261 and pIRES-CEACAM6/SL3261 groups. By contrast, a significantly fewer number of tumors, albeit with a higher density of CD3+CD8+, CD56+ and a lower density of Foxp3+ tumor-infiltrating lymphocyte (TIL) cells was detected in the pIRES-CEACAM6-4-1BBL/SL3261 group of rats. The results indicated that vaccination with recombinant attenuated Salmonella harboring the CEACAM6 and 4-1BBL gene efficiently increased the number of CD3+CD8+ TIL and NK cells, decreased the number of FOXP3 cells and inhibited the development of DMH-induced colorectal cancer in rats.

Recombinant Salmonella-based 4-1BBL vaccine enhances T cell immunity and inhibits the development of colorectal cancer in rats: in vivo effects of vaccine containing 4-1BBL

Background

Immunotherapy with vaccines is attractive for the treatment of cancer. This study is aimed at determining the effect of recombinant Salmonella (SL3261)-based 4-1BB ligand (4-1BBL) vaccine on the development of colorectal cancers and the potential immune mechanisms in rats.

Results

In comparison with that in the PBS group, similar levels of 4-1BBL expression, the frequency of T cells, IFN-γ responses, and comparable numbers of tumors were detected in the SL3261 and SL3261C groups of rats. In contrast, significantly fewer numbers of tumors, increased levels of 4-1BBL expression in the spleens and colorectal tissues, higher frequency of peripheral blood and splenic CD3⁺CD25⁺ T cells, and stronger splenic T cell IFN-γ responses were detected in the SL3261R group of rats.

Conclusion

Our results indicated that vaccination with recombinant attenuated Salmonella harboring the 4-1BBL gene efficiently enhanced T cell immunity and inhibited the development of carcinogen-induced colorectal cancers in rats.

Recombinant human CD137L for cancer immunotherapy: effects of different fusions and linkers on its activity

Co-stimulatory molecules can be efficiently produced as a recombinant protein in E. coli with a large range of applications in the fields of immunotherapy. However, whether, different fusions that would affect their functions have rarely been analyzed. To explore the effects of different fusions and linkers on the molecular conformation and activity of CD137 ligand (CD137L), a recombinant human CD137L protein (rhCD137L) library, which consists of the entire extracellular domain of human CD137L fused to N- or C-terminal His-tag through different linkers, was constructed and all rhCD137Ls were, respectively, expressed in E. coli BL21 (DE3) strain carrying a chaperone plasmid pG-Tf2. After purification of the soluble rhCD137Ls, the recombinant fusion proteins could markedly promote the growth of activated T cells, but their effects on cytokine productions were different from each other. The present work indicated that, although all rhCD137Ls have desired biological activity, different fusions and linkers did affect their structures and functions. Consequently, rational design of a library is a necessary and feasible approach for fusion proteins in order to obtain a satisfactory drug candidate for further development.

The treatment and prevention of mouse melanoma with an oral DNA vaccine carried by attenuated Salmonella typhimurium

Therapeutic vaccines of cancer are attractive for their capacity of breaking the immune tolerance and invoking long-term immune response targeting cancer cells without autoimmunity. An efficient antigen delivery system is the key issue of developing an effective cancer vaccine. Attenuated Salmonella typhimurium as the carrier of cancer vaccine are able to transfer DNA from the prokaryote to the eukaryote and preferentially replicate within the tumor tissue. Heat shock protein 70 delivers the tumor-associated antigens to antigen presenting cells through its polypeptide-binding domain and breaks immune tolerance of the cancer cells. Here we described a novel low-copy-number DNA vaccine based on the Hsp70-TAA complex and carried by the attenuated S. typhimurium strain SL3261. Oral administration of this vaccine elicited specific CTL-mediated lysis of the melanoma tumor cells and marked activation of the T-cells. The therapeutic vaccine effectively protected 57.1% C57BL/6J mice from lethal challenge with B16F10 melanoma tumor cells in prophylactic settings and eraicated 62.5% tumor growth in therapeutic settings. This approach may provide a new strategy for the prevention and treatment of cancer.