A niosome formulation modulates the Th1/Th2 bias immune response in mice and also provides protection against anthrax spore challenge

Abstract

IntroductionIn this study, we have investigated the immunogenicity and protective efficacy of a niosomal formulation encapsulating protective antigen (PA) and PA domain 4 (D4) of Bacillus anthracis.MethodsNonionic surfactant–based vesicles (NISV) + PA and NISV + D4 were prepared from span-60 and cholesterol by reverse-phase evaporation method and were evaluated for in vitro characteristics and immunological studies.ResultsParticle characterization using transmission electron microscopy and atomic force microscopy analysis showed that the niosomal formulation was spherical in shape. The entrapment efficiency values were calculated to be 58.5% and 44.75% for PA and D4, respectively. Confocal microscopy and flow cytometry studies showed an enhanced uptake of antigen in THP1 macrophages by niosome as compared to antigen only. An in vitro release assay showed a burst release of antigen from niosome within 24 hours followed by a gradual release for 144 hours. Immunological studies showed that both PA- and D4-encapsulated niosome elicited a robust IgG titer. Antibody isotyping and cytokine profile showed that NISV + PA and NISV + D4 enhanced both Th1 and Th2 responses in mice, suggesting a mixed Th1/Th2 response. Both NISV + PA and NISV + D4 elicited high levels of anti-inflammatory cytokine interleukin-10 with low levels of pro-inflammatory cytokine tumor necrosis factor-α, suggesting the anti-inflammatory property of niosome. Both the niosomal formulations were also able to confer protection against BA infection as compared to only PA and D4.ConclusionPA and D4 encapsulated NISV formulation could modulate both the Th1 and Th2 adaptive immune system and was found to be a better prophylactic against anthrax.

Co-Administration of Aluminium Hydroxide Nanoparticles and Protective Antigen Domain 4 Encapsulated Non-Ionic Surfactant Vesicles Show Enhanced Immune Response and Superior Protection against Anthrax

“…This is in agreement with our previous results, where it was shown that AH np promotes IgG2a production against D4 [ 41 ]. Similarly, NISV-D4 promoted IgG2a production, which is in agreement with our previous results [ 40 ]. In this study, the novel combinatorial nanoformulation AH np/NISV-D4 yielded a mixed IgG1/IgG2a response.…”

“…D4-encapsulated NISV was prepared and the protein content was determined as described in our previous publication [ 40 ]. Briefly, 5.5 mg of Span 60 and 7.4 mg of cholesterol were dissolved in 5 mL of chloroform in a round-bottom flask.…”

“…Similarly, IgG1 and IgG2a antibody titers were determined by using secondary anti-mouse IgG1 or IgG2a HRP-conjugated antibody [ 40 ].…”

Materials for Immunotherapy

“…A follow‐up study was performed by Omidfar and co‐workers to optimize the release rate of BSA from niosomes . Most recently, Bhatnagar and co‐workers developed niosomes to deliver protective antigens for immunization against an anthrax spore challenge in mice . While there are still relatively few examples of niosomes used in immunotherapy, we believe this is an auspicious vehicle for translation due to its immunogenic performance, scale and ease of formulation, and low cost…”

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

“…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.…”