Functionalized chitosan-G-poly caprolactone vaccine delivery system fabricated to display antigen–antibody immune complexes of Mycobacterium tuberculosis elicits immune response in Ex-vivo model

Background

Vaccine development against tuberculosis remains a global health imperative, necessitating robust immunogenicity and safety profiles. Nanoparticle-based delivery systems offer promising avenues to enhance vaccine efficacy while ensuring tolerability. This study explores the utilization of chitosan micelles as a delivery platform for immune complex vaccination against tuberculosis. Leveraging two key antigens of Mycobacterium tuberculosis, namely HspX and Mpt51, known for their relevance in latent tuberculosis and its co-infection with the human immunodeficiency virus, immune complexes were synthesized in vitro using antibodies raised against these antigens. The immune complexes were then conjugated onto chitosan micelles, characterized for their physicochemical properties, and evaluated for their biocompatibility and immunogenicity.

Results

Chitosan nanoparticles conjugated with either antigen or its immune complexes were synthesized as micelles and physicochemical characterizations confirm the formation of micelles without altering the polymer composition. These immune complex-conjugated chitosan micelles were found to be safe, exhibiting no significant hemolytic and cytotoxic activity even at a higher concentration of 400 µg/ml. Peripheral blood mononuclear cells upon stimulation with immune complex-conjugated chitosan micelles showed enhanced cellular uptake and one to two-fold increased expression of key immune markers—interferon gamma and CD-86.

Conclusions

These findings underscore the potential of chitosan nanoparticles as a versatile delivery platform for immune complex vaccination against tuberculosis. While limitations exist, such as including only two markers of immune modulation, this study lays a foundation for future investigations into immune complex vaccine potential in animal models. In conclusion, chitosan micelles carrying immune complexes of HspX and Mpt51 tuberculosis antigens exhibit promising immunogenicity, highlighting their potential as a platform for multi-antigenic vaccine components warranting further in vivo studies.