In vitro spleen cell cytokine responses of adult mice immunized with a recombinant PorA (major outer membrane protein [MOMP]) from Campylobacter jejuni

Enhanced and Prolonged Immunogenicity in Mice of Thermally Stabilized Fatty Acid-Conjugated Vaccine Antigen

BACKGROUND/OBJECTIVES

Influenza vaccines require good thermal stability without the need for refrigerator storage. Although the fatty acid-conjugated hemagglutinin (Heg) vaccine antigen provides good stability in both solid and liquid states, its therapeutic effectiveness must be validated in vivo. This study aimed to investigate the immunogenicity of the thermally stabilized Heg-oleic acid conjugate (HOC) and compare it with native Heg as a reference.

METHOD

To evaluate HOC immunogenicity, an enzyme-linked immunosorbent assay was used to measure hemagglutinin inhibition (HI) titers, serum IgG antibody titers (IgG1, IgG2a), and cytokine secretion levels (IFN-γ, IL-4) in BALB/c mice after intramuscular (IM) injection.

RESULTS

Thermally stabilized HOC induced higher and more sustained serum IgG1 and IgG2a responses than the native Heg vaccine antigen. IgG1 is typically associated with a Th2 response, whereas IgG2a is associated with a Th1 response. HOC appeared to enhance both responses, inducing a more balanced immune response. Moreover, HOC antigens stimulate broader immune responses, suggesting stronger and longer-lasting immune memory. The cytokine levels of IFN-γ (2.8-fold) and IL-4 (6-fold) were significantly increased in the HOC-immunized group compared to the Heg group. IFN-γ, a cytokine that activates the Th1 immune response, demonstrated the enhanced ability of HOC to induce a Th1 response. IL-4, a cytokine that promotes the Th2 response, indicated that HOC also strongly induced a Th2 response. The thermal stability of HOC antigens was crucial for maintaining their structural integrity, enabling the continuous exposure to the stable antigen without denaturation. This allows immune cells to recognize stable antigens efficiently and form long-term immune memory.

CONCLUSIONS

The stability of HOC antigens enhanced the antigen processing efficiency of antigen-presenting cells (APCs) and stimulated immune responses. The fatty acid-conjugated vaccine antigen could provide improved storage stability but also enhance immunogenic efficacy compared to the native antigen, supporting its potential for further applications.

High protein diet increases the risk of allergic sensitization but not asthma in mice through modulation of the cytokine milieu toward Th2 bias

Introduction

The role of different nutrients in allergic sensitization is not clear. In this study we aimed to determine the effect of high protein (HP) diet on allergic sensitization, cytokine profile, and asthma in mice.

Methods

Seven- to eight-week old female BALB/c mice were fed either normal (ND) or HP diet and were sensitized with ovalbumin intraperitoneally followed by intranasal challenge. Allergic sensitization was tested by measuring anti-ovalbumin (OVA) IgE, IgG1, and IgG2a antibodies. Cytokine levels were tested by multiplex ELISA in splenocyte supernatants after stimulation. Airway inflammation was tested by measuring total and differential cell counts in bronchoalveolar lavage fluid and by measuring bronchial mucus production, goblet cell hyperplasia and perivascular and peribronchial inflammation severity scores by histologic examination.

Results

Mice fed HP diet had a significant increase in weight and higher levels of OVA-specific IgE and IgG1 antibodies compared to the ND group (P-values 0.002, 0.007 and <0.001, respectively). In addition, they showed a selective Th2 bias in cultured splenocyte supernatants compared to the ND group as demonstrated by higher IL-4 and IL-6 levels (P-values <0.001 and 0.011, respectively) and higher ratios of Th2 to Th1 cytokines. However, the level of airway inflammation was comparable between both groups.

Conclusions

HP diet increases the risk of allergic sensitization though increase in Th2 cytokines. Efforts should be made to define the upper limit of protein in the diet that does not predispose to allergic sensitization. The effect of diet on health should remain a focus of research for the establishment of optimal health and resilience.

The Immunomodulatory Effects of A2 β-Casein on Immunosuppressed Mice by Regulating Immune Responses and the Gut Microbiota

The aim of this study was to investigate the immunomodulatory effects of A2 β-casein (β-CN) in cyclophosphamide-induced immunosuppressed BALB/c mice. Experiments conducted in vitro revealed that A2 β-CN digestive products have potent immunostimulatory activities. Animal studies demonstrated that A2 β-CN improved the immunological organ index reduction trend caused by cyclophosphamide, reduced the pathological damage to the spleen tissue in immunosuppressed mice, increased the release of IL-17A, IgG, and IgA, and reduced the production of IL-4. By regulating the relative abundance of advantageous bacteria like Oscillospira, Lactobacillus, and Bifidobacteria and harmful bacteria like Coprococcus and Desulfovibrionaceae, A2 β-CN improved gut microbiota disorders in immunosuppressed mice. Moreover, A2 β-CN promoted the production of short-chain fatty acids and increased the diversity of the gut microbiota. Therefore, ingestion of A2 β-CN is beneficial to the host's immune system and gut health. These findings provide insights for the future application of A2 β-CN-related dairy products.

Potential of a novel flagellin epitope as a broad-spectrum vaccine candidate against enteric fever

Relentless emergence of antibiotic resistant Salmonella strains, coupled with the drawbacks associated with currently available vaccines against enteric fever, warrants an urgent need to look for new vaccine candidates. Out of the multiple virulence factors harbored by Salmonella, flagella are regarded as one of the most important targets of innate as well as adaptive immune response. Individual Salmonella serotypes alternate between expression of two different antigenic forms encoded by fliC and fljB genes, respectively thereby employing this as a strategy to escape the host immune response. In the present study, using various immunoinformatic approaches, a flagellin epitope, present in both antigenic forms of typhoidal Salmonellae has been targeted. Following B-cell epitope and B-cell derived T-cell epitope prediction and interaction studies with major histocompatibility complexes using molecular docking, a peptide epitope was selected. Further, it was screened for its presence in majority of typhoidal serovars along with other useful attributes, in silico. Thereafter, safety studies were performed with the synthesized peptide. Subsequently, immunization studies were carried out using S. Typhi as well as S. Paratyphi A induced murine peritonitis model. Active immunization with peptide-BSA conjugate resulted in 75% and 80% mice survival following lethal challenge with S. Typhi and S. Paratyphi A respectively, along with a significant IgG antibody titer, thereby highlighting its immunogenic potential. Reduced bacterial burden in vital organs along with improved histoarchitecture and cytokine levels further substantiated the protective efficacy of the proposed candidate. Passive immunization studies with the candidate verified the protective efficacy of the generated antibodies against lethal challenge of bacteria in mice. Given the endemic nature of enteric fever and the antigenic variability observed in Salmonella serotypes, present study highlights the importance of using a vaccine candidate, which, along with generating a strong immune response, also exhibits a broad coverage against both, S. Typhi as well as S. Paratyphi A strains.

A mixture of Panax ginseng and Scrophularia buergeriana improves immune function in an immunosuppressed murine model

BACKGROUND

Immunomodulatory drugs are currently used for immunosuppressed individuals, but adverse side effects have been reported. Although Panax ginseng and Scrophularia buergeriana are known to have respective pharmacological properties, the potential of a mixture of Panax ginseng and Scrophularia buergeriana (Isam-Tang, IST) as an immunomodulatory drug has not yet been studied.

PURPOSE

The present study was designed to assess the immunomodulatory activity of IST and p-coumaric acid (pCA), an active compound of IST, in the immune system.

METHODS

The levels of immunostimulatory cytokines, nitrite, inducible nitric oxide synthase (iNOS), NF-kB activation, and proliferation were examined in RAW264.7 cells, primary splenocytes and splenic NK cells isolated from normal mouse spleen, and in cyclophosphamide-induced immunosuppressed mice using ELISA, quantitative real-time PCR, Western blotting, and immunofluorescence staining.

RESULTS

IST or pCA treatment increased the production of immunostimulatory cytokines and nitrite and the expression of iNOS in RAW264.7 cells and splenocytes. IST or pCA also induced NF-κB signaling activation and promoted the phagocytic activity of RAW264.7 cells. In addition, the splenocyte proliferation and splenic NK activity were enhanced by IST or pCA. IST or pCA increased the levels of immunostimulatory cytokines in immunosuppressed mice and ameliorated splenic tissue damage.

CONCLUSION

These findings suggest that IST supplementation may be used to enhance immune function.