Adjuvant Potential of Poly-α- l -Glutamine from the Cell Wall of Mycobacterium tuberculosis

Abstract

Novel adjuvants are in demand for improving the efficacy of human vaccines. The immunomodulatory properties of cell wall components have been highlighted in the formulation of complete Freund's adjuvant (CFA). We have explored the adjuvant potential of poly-α-l-glutamine (PLG), a lesser-known constituent of the pathogenic mycobacterial cell wall. Immune parameters indicated that the adjuvant potency of PLG was statistically comparable to that of CFA and better than that of alum in the context of H1 antigen (Ag85B and ESAT-6 fusion). At 1 mg/dose, PLG augmented the immune response of Ag85B, BP26, and protective antigen (PA) by increasing serum antibodies and cytokines in the culture supernatant of antigen-stimulated splenocytes. PLG modulated the humoral response of vaccine candidate ESAT-6, eliciting significantly higher levels of total IgG and isotypes (IgG1, IgG2a, and IgG2b). Additionally, the splenocytes from PLG-adjuvanted mice displayed a robust increase in the Th1-specific gamma interferon, tumor necrosis factor alpha, interleukin-2 (IL-2), Th2-specific IL-6 and IL-10, and Th17-specific IL-17A cytokines upon antigenic stimulation. PLG improved the protective efficacy of ESAT-6 by reducing bacillary load in the lung and spleen as well as granuloma formation, and it helped in maintaining vital health parameters of mice challenged with The median survival time of PLG-adjuvanted mice was 205 days, compared to 146 days for dimethyl-dioctadecyl ammonium bromide-monophosphoryl lipid A (DDA-MPL)-vaccinated groups and 224 days for BCG-vaccinated groups. PLG enhanced the efficiency of the ESAT-6 vaccine to the level of BCG and better than that of DDA-MPL ( < 0.05), with no ill effect in C57BL/6J mice. Our results propose that PLG is a promising adjuvant candidate for advanced experimentation.

<p>Novel Approach for Transdermal Delivery of Rifampicin to Induce Synergistic Antimycobacterial Effects Against Cutaneous and Systemic Tuberculosis Using a Cationic Nanoemulsion Gel</p>

“…53 Recently, poly-αl-glutamine on the cell wall of Mycobacterium tuberculosis has been evaluated as a novel adjuvant with potential to improve the efficacy of human vaccines. 54 Nanoemulsions such as those developed in this study may also have potential as delivery systems for topical vaccines.…”

<p>Crystalline and Amorphous Preparation of Aluminum Hydroxide Nanoparticles Enhances Protective Antigen Domain 4 Specific Immunogenicity and Provides Protection Against Anthrax</p>

“…The antigen D4-specific presence of total IgG and isotypes IgG1 and IgG2-a antibody titers from the immunized mice sera was evaluated by enzyme-linked immunosorbent assay (ELISA) following the previously published method. 36 Briefly, 500 ng of purified recombinant protein D4 was coated in 96-well microtiter plates and incubated overnight at at 4°C. The next day, the protein solution was aspirated from the plate and washed twice with 1⨰ PBS containing Tween-20 (0.05% v/v).…”

“…In order to know the plausible release profile of antigen D4 from AH nps at the injection site after immunization in mice, the in-vitro antigen release assay was performed by following the method published previously. 36,38 Briefly, 250 µg of D4 were incubated with 500 µg of the prepared AH nps adjuvants for 20 min. This formulation was mixed with 1⨰ PBS at a ratio of 1:3 to form a stock solution and incubated at 37°C with 80 rpm shaking speed.…”

Mycobacterium tuberculosis Rv3628 is an effective adjuvant via activation of dendritic cells for cancer immunotherapy

“…The observation that the increases in BDCA3 + DCs were similar to those in BDCA1 + DCs suggests that the superior capacity of BDCA3 + cells (analogous to the mouse CD8α + DC subset) to cross-present Ag and induce Th1 cell responses may be enhanced by exposure to this adjuvant ( Figure 8 ). Other mycobacterial proteins have been reported to have adjuvanticity against tumors in mice, 34 , 35 , 36 , 37 and direct comparisons remain to be undertaken.…”