Oral Immunization With a M Cell-Targeting Recombinant L. Lactis Vaccine LL-plSAM-FVpE Stimulate Protective Immunity Against H. Pylori in Mice

Oral Live-Carrier Vaccine of Recombinant Lactococcus lactis Inducing Prophylactic Protective Immunity Against Helicobacter pylori Infection

Helicobacter pylori infects the gastric mucosa and induces chronic gastritis, peptic ulcers, and gastric cancer. Research has demonstrated that vaccination can induce a protective immune response and prevent H. pylori infection. Oral administration of the Lactococcus lactis live-carrier vaccine is safe and easily complied with by the public. In this study, two recombinant L. lactis strains were constructed that expressed antigens of H. pylori urease subunit alpha (UreA) and UreA fused with Escherichia coli heat-labile toxin B subunit (LTB-UreA), named LL-UreA and LL-LTB-UreA, respectively. The expression of antigen proteins was confirmed by Western blotting analysis. Survival assessment indicated that the engineered L. lactis could colonize in the digestive tract of BALB/c mice up to 10 days after the last oral administration with our immunization protocol. The ability to induce immune response and immune protective efficacy of the L. lactis were confirmed. These results indicated that oral administration with LL-UreA or LL-LTB-UreA could induce UreA-specific mucosal secretory IgA (sIgA) and cellular immune response, significantly increasing the cytokines levels of interferon-gamma (IFN-γ), interleukin (IL)-17A, and IL-10, together with the proportion of CD4+IFN-γ+ T cells and CD4+IL17A+ T cells. More importantly, oral administration of LL-UreA and LL-LTB-UreA brought about effective protection in mice to prevent H. pylori infection, especially LL-UreA, resulting in 70% of mice showing no H. pylori colonization and the remaining 30% showing only low levels of colonization. These findings underscore the potential of using orally administered engineered L. lactis vaccines to prevent H. pylori infection.

Novel therapeutic regimens against Helicobacter pylori: an updated systematic review

Helicobacter pylori (H. pylori) is a strict microaerophilic bacterial species that exists in the stomach, and H. pylori infection is one of the most common chronic bacterial infections affecting humans. Eradicating H. pylori is the preferred method for the long-term prevention of complications such as chronic gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer. However, first-line treatment with triple therapy and quadruple therapy has been unable to cope with increasing antibacterial resistance. To provide an updated review of H. pylori infections and antibacterial resistance, as well as related treatment options, we searched PubMed for articles published until March 2024. The key search terms were "H. pylori", "H. pylori infection", "H. pylori diseases", "H. pylori eradication", and "H. pylori antibacterial resistance." Despite the use of antimicrobial agents, the annual decline in the eradication rate of H. pylori continues. Emerging eradication therapies, such as the development of the new strong acid blocker vonoprazan, probiotic adjuvant therapy, and H. pylori vaccine therapy, are exciting. However, the effectiveness of these treatments needs to be further evaluated. It is worth mentioning that the idea of altering the oxygen environment in gastric juice for H. pylori to not be able to survive is a hot topic that should be considered in new eradication plans. Various strategies for eradicating H. pylori, including antibacterials, vaccines, probiotics, and biomaterials, are continuously evolving. A novel approach involving the alteration of the oxygen concentration within the growth environment of H. pylori has emerged as a promising eradication strategy.

Recombinant L. lactis vaccine LL-plSAM-WAE targeting four virulence factors provides mucosal immunity against H. pylori infection

BACKGROUND

Helicobacter pylori (H. pylori) causes chronic gastric disease. An efficient oral vaccine would be mucosa-targeted and offer defense against colonization of invasive infection in the digestive system. Proteolytic enzymes and acidic environment in the gastrointestinal tract (GT) can, however, reduce the effectiveness of oral vaccinations. For the creation of an edible vaccine, L. lactis has been proposed as a means of delivering vaccine antigens.

RESULTS

We developed a plSAM (pNZ8148-SAM) that expresses a multiepitope vaccine antigen SAM-WAE containing Urease, HpaA, HSP60, and NAP extracellularly (named LL-plSAM-WAE) to increase the efficacy of oral vaccinations. We then investigated the immunogenicity of LL-plSAM-WAE in Balb/c mice. Mice that received LL-plSAM-WAE or SAM-WAE with adjuvant showed increased levels of antibodies against H. pylori, including IgG and sIgA, and resulted in significant reductions in H. pylori colonization. Furthermore, we show that SAM-WAE and LL-plSAM-WAE improved the capacity to target the vaccine to M cells.

CONCLUSIONS

These findings suggest that recombinant L. lactis could be a promising oral mucosa vaccination for preventing H. pylori infection.

An M cell-targeting recombinant L. lactis vaccine against four H. pylori adhesins

The acidic environment and enzyme degradation lead to oral vaccines often having little immune effect. Therefore, it is an attractive strategy to study an effective and safe oral vaccine delivery system that can promote gastrointestinal mucosal immune responses and inhibit antigen degradation. Moreover, the antigens uptake by microfold cells (M cells) is the determining step in initiating efficient immune responses. Therefore, M cell-targeting is one promising approach for enhancing oral vaccine potency. In the present study, an M cell-targeting L. lactis surface display system (plSAM) was built to favor the multivalent epitope vaccine antigen (FAdE) to achieve effective gastrointestinal mucosal immunity against Helicobacter pylori. Therefore, a recombinant Lactococcus lactic acid vaccine (LL-plSAM-FAdE) was successfully prepared, and its immunological properties and protective efficacy were analyzed. The results showed that LL-plSAM-FAdE can secretively express the recombinant proteins SAM-FAdE and display the SAM-FAdE on the bacterial cell surface. More importantly, LL-plSAM-FAdE effectively promoted the phagocytosis and transport of vaccine antigen by M cells in the gastrointestinal tract of mice, and simulated high levels of cellular and humoral immune responses against four key H. pylori adhesins (Urease, CagL, HpaA, and Lpp20) in the gastrointestinal tract, thus enabling effective prevention of H. pylori infection and to some extent eliminating H. pylori already present in the gastrointestinal tract. KEY POINTS: • M-cell-targeting L. lactis surface display system LL- plSAM was designed • This system displays H. pylori vaccine-promoted phagocytosis and transport of M cell • A promising vaccine candidate for controlling H. pylori infection was verified.

Expression and purification of epitope vaccine against four virulence proteins from Helicobacter pylori and construction of label-free electrochemical immunosensor

The epitope vaccine against four virulence proteins (FVpE) from Helicobacter pylori (H. pylori) was expressed and purified. Western blot and Enzyme-linked Immunosorbent Assays (ELISA) were used to identify and investigate the immunoreactivity of FVpE protein. The immune-sensing platform based on titanium carbide/colloidal gold nanoparticles@carbon nanofiber/ionic liquid composites electrode was constructed for immobilizing FVpE. Electrochemical impedance spectroscopy (EIS) was used to study the electrochemical properties of the modified electrodes. The relevant influenced factors were optimized including pH value, antigen concentration, and incubating time. The prepared H. pylori label-free electrochemical immunosensor was used for antibody detection using differential pulse voltammetry (DPV). Under the optimal experimental conditions, the linear ranges of H. pylori antibodies, including anti-H. pylori, cytotoxin-associated gene A (CagA), vacuolating cytotoxin-associated gene A (VacA), and urease A (UreA), were all 0.1-5 ng mL-1, except urease B (UreB, 0.1-4.5 ng mL-1). The selectivity study showed that other antibodies had little influence on the detection of H. pylori antibodies. The immunosensor could be used to detect serum samples, and the recoveries were in the range of 68.5%-100.5%.

Urolithin B alleviates Helicobacter pylori-induced inflammation and oxidative stress in mice

BACKGROUND

Helicobacter pylori is one of the most common chronic bacterial infections. Active eradication of H. pylori infection is rare due to the fact that most infected patients are asymptomatic and the use of large amounts of antibiotics in eradication therapy leads to severe side effects. Urolithin B (UB) is an additional major intestinal metabolite of ellagic acid (EA), which has been shown to possess anti-inflammatory, antioxidant, and antiapoptotic biological activities. Preventing the incidence of H. pylori-related gastric disease and reducing the damage to the host by H. pylori is a current approach to control H. pylori infection. In this study, we explored the effect of UB on H. pylori infection.

MATERIALS AND METHODS

The effects of UB on inflammation and oxidative stress induced by H. pylori in vivo and in vitro were investigated by qPCR, ELISA, HE staining, IHC staining, etc. RESULTS: UB reduced the adhesion and colonization of H. pylori and improved H. pylori-induced inflammation and oxidative stress in vivo and in vitro. Moreover, UB had better anti-inflammatory and antioxidant effects than clarithromycin (CLR) and metronidazole (MET). In addition to inhibiting the secretion of CagA, UB reduced tissue damage by H. pylori infection.

CONCLUSIONS

UB was effective in improving damage caused by H. pylori.

How Long Will It Take to Launch an Effective Helicobacter pylori Vaccine for Humans?

Helicobacter pylori infection often occurs in early childhood, and can last a lifetime if not treated with medication. H. pylori infection can also cause a variety of stomach diseases, which can only be treated with a combination of antibiotics. Combinations of antibiotics can cure H. pylori infection, but it is easy to relapse and develop drug resistance. Therefore, a vaccine is a promising strategy for prevention and therapy for the infection of H. pylori. After decades of research and development, there has been no appearance of any H. pylori vaccine reaching the market, unfortunately. This review summarizes the aspects of candidate antigens, immunoadjuvants, and delivery systems in the long journey of H. pylori vaccine research, and also introduces some clinical trials that have displayed encouraging or depressing results. Possible reasons for the inability of an H. pylori vaccine to be available over the counter are cautiously discussed and some propositions for the future of H. pylori vaccines are outlined.