Biodegradable polylactide microspheres enhance specific immune response induced by Hepatitis B surface antigen

Area of Science:

• Immunology
• Vaccinology
• Biomaterials Science

Background:

• Hepatitis B (HB) is a prevalent liver disease globally.
• Current HB vaccines with alum adjuvants primarily induce Th2 immunity, lacking robust Th1 and CTL responses needed for preventing maternal transmission.
• Polymeric microspheres, like those from poly (D, L-lactide) (PLA), offer potential for advanced vaccine delivery systems.

Purpose of the Study:

• To develop and evaluate a novel Hepatitis B (HB) vaccine formulated with poly (D, L-lactide) (PLA) microspheres.
• To assess the immunogenicity of the PLA microsphere-based HB vaccine, focusing on Th1 immune responses.
• To investigate the potential of PLA microspheres as effective adjuvants for HB vaccines.

Main Methods:

• PLA microspheres were synthesized using the premix membrane emulsification method.
• BALB/c mice were immunized with the microsphere-based HB vaccine.
• Immunogenicity was evaluated through Enzyme-linked ImmunoSpot (ELISPOT) assays, (51)Cr cytotoxicity assays, and assessment of antibody production.
• Phagocytosis of Hepatitis B surface antigen (HBsAg) by dendritic cells was analyzed.

Main Results:

• The PLA microsphere vaccine significantly increased interferon-gamma (IFN-γ)-producing splenocytes and CD8(+) T cells.
• Enhanced specific cell lysis was observed in the microsphere vaccine group compared to the HBsAg-only group.
• Antibody production was comparable to the traditional alum-adjuvanted HB vaccine.
• Dendritic cell phagocytosis of HBsAg was more pronounced with the microsphere vaccine.

Conclusions:

• PLA microspheres demonstrate potential as effective adjuvants for HB vaccines.
• This novel microsphere formulation elicits a robust Th1 immune response, surpassing current vaccine limitations.
• The developed PLA microsphere-based HB vaccine shows promise for improved protection against Hepatitis B infection.