Specific T cell induction using iron oxide based nanoparticles as subunit vaccine adjuvant

Area of Science:

• Immunology
• Nanotechnology
• Vaccinology

Background:

• Metal-based nanoparticles (NPs) are known to stimulate innate immunity.
• The potential of NPs to enhance specific cellular immune responses has not been previously demonstrated.
• Developing effective subunit vaccines requires potent adjuvants to elicit robust cellular immunity.

Purpose of the Study:

• To investigate the adjuvant properties of iron oxide-based nanoparticles (NPs).
• To evaluate the generation of specific T-helper 1 (Th1), T-helper 17 (Th17), and cytotoxic T-cell 1 (Tc1) immune responses.
• To assess the efficacy of an iron oxide NP-adjuvanted subunit vaccine against *Mycobacterium tuberculosis* (Mtb).

Main Methods:

• Synthesis and characterization of citrate-coated MnFe₂O₄ NPs using co-precipitation and transmission electron microscopy.
• Formulation of a subunit vaccine using a fusion protein (CMX) from *M. tuberculosis* antigens and NPs.
• Evaluation of protein corona formation using dynamic light scattering and field-emission scanning electron microscopy.
• Assessment of immunization routes (subcutaneous and intranasal) and strategies for vaccine delivery.

Main Results:

• Subcutaneous administration of the NP-adjuvanted vaccine induced specific Th1 and CD8+IFN-γ+ (Tc1) responses.
• Intranasal vaccination primarily induced Th1, Th17 (CD4+IL-17+), and Tc1 responses in the lungs.
• A mixed subcutaneous-intranasal strategy elicited Th1 and splenic Tc1 responses, but not lung Th17 responses.
• Subcutaneous vaccination significantly reduced the bacterial load in Mtb-challenged animals.

Conclusions:

• Iron oxide-based NPs demonstrate significant adjuvant properties, successfully generating specific Th1, Th17, and Tc1 cellular immune responses.
• The NP-adjuvanted subunit vaccine shows potential for developing a tuberculosis vaccine, as evidenced by reduced bacterial load.
• The route of administration critically influences the type and location of the induced immune response.