Journal of Mucosal Immunology Research
Open Access

Mucosal vaccination; Immune protection; Mucosal immunity; Adjuvants; Delivery systems

Introduction

Vaccination remains one of the most effective strategies for preventing infectious diseases. Traditional parenteral vaccines primarily induce systemic immunity, often overlooking mucosal surfaces where many pathogens initially enter the body. Mucosal vaccines aim to stimulate local immune responses at mucosal sites, such as the respiratory, gastrointestinal, and urogenital tracts, thereby preventing pathogen colonization and transmission.

Mechanisms of mucosal immunity

Mucosal immunity involves a complex interplay of innate and adaptive immune responses. Mucosal-associated lymphoid tissues (MALT), including Peyer's patches, nasal-associated lymphoid tissue (NALT), and bronchus-associated lymphoid tissue (BALT), play pivotal roles in antigen sampling and immune activation. Understanding these mechanisms is crucial for designing effective mucosal vaccines.

Types of mucosal vaccines

Advances in mucosal vaccination strategies encompass various approaches

Live attenuated vaccines: Replicating within mucosal tissues, these vaccines induce robust local and systemic immune responses.

Subunit vaccines: Utilizing purified antigens combined with mucosal adjuvants to enhance immunogenicity.

Viral vector vaccines: Engineered vectors deliver antigen genes to mucosal epithelial cells, triggering immune responses [1-4].

Mucosal adjuvants

Effective mucosal vaccines often require adjuvants to enhance immune responses. Key adjuvants include:

Cholera toxin subunit B (CTB): Enhances antigen uptake and activates mucosal immunity.

Heat-labile enterotoxin (LT): Stimulates mucosal immune responses through similar mechanisms as CTB.

Delivery systems

Developing efficient delivery systems is critical for mucosal vaccine success:

Nanoparticles: Enhance antigen stability and mucosal penetration.

Microparticles: Controlled release systems for sustained immune stimulation.

Intranasal Sprays: Non-invasive delivery for respiratory mucosal vaccines.

Immunological responses

Mucosal vaccines elicit unique immune responses compared to parenteral vaccines:

Secretory IgA (sIgA) production: Key in mucosal defense, preventing pathogen adherence and invasion.

Tissue-resident memory T cells (TRM): Provide rapid immune responses upon pathogen re-exposure.

Clinical applications

Mucosal vaccines show promise against various pathogens

Influenza: Intranasal vaccines induce mucosal and systemic immunity.

Rotavirus: Oral vaccines prevent severe gastroenteritis in infants.

COVID-19: Nasal vaccines under development for enhanced mucosal immunity.

Challenges and future directions

Despite advancements, several challenges remain:

Safety concerns: Potential adverse effects of mucosal adjuvants.

Stability issues: Maintaining antigen integrity during mucosal delivery.

Regulatory hurdles: Approval processes for novel mucosal vaccines.

Future research should focus on

Innovative adjuvants: Safe and effective alternatives to current adjuvants.

Targeted delivery systems: Improving antigen delivery to specific mucosal sites.

Combination approaches: Integrated strategies for broad-spectrum mucosal protection.

Discussion

Advances in mucosal vaccination strategies have revolutionized immunology by enhancing immune protection against various pathogens [5-8]. Mucosal surfaces, such as those in the respiratory, gastrointestinal, and urogenital tracts, represent the primary sites of entry for many pathogens. Traditional vaccines primarily stimulate systemic immune responses, often overlooking mucosal immunity crucial for blocking initial infection. Recent research has focused on developing vaccines that can effectively induce mucosal immunity. One promising approach involves using attenuated viruses or bacteria that can colonize mucosal surfaces without causing disease, eliciting robust local immune responses. For example, intranasal vaccines against influenza and respiratory syncytial virus have shown efficacy in inducing protective mucosal immunity in addition to systemic immunity. Nanotechnology has also contributed significantly to mucosal vaccination strategies. Nanoparticles can encapsulate vaccine antigens and adjuvants, facilitating their targeted delivery to mucosal surfaces. This approach enhances antigen uptake by mucosal epithelial cells and boosts local immune responses, potentially offering broader protection against infections. Furthermore, the development of novel adjuvants has been pivotal in enhancing mucosal vaccine efficacy [9,10]. Adjuvants like cholera toxin subunit B and heat-labile enterotoxin from Escherichia coli can enhance mucosal immune responses by activating innate immune pathways and promoting antigen uptake by mucosal cells. Advances in mucosal vaccination strategies not only aim to prevent infections but also hold promise for addressing challenges like vaccine hesitancy and improving vaccine coverage. By harnessing the body's natural mucosal defenses, these innovative approaches offer a more comprehensive and effective means of protection against a wide range of pathogens. Continued research and development in this field are crucial for realizing the full potential of mucosal vaccination in global health initiatives.

Conclusion

Advances in mucosal vaccination strategies hold immense promise for enhancing immune protection against infectious diseases. Continued research and innovation in adjuvants, delivery systems, and understanding mucosal immunity mechanisms are essential to overcome existing challenges and realize the full potential of mucosal vaccines.

References

1. Kilgore PE, Salim AM, Zervos MJ, Schmitt H (2016) Pertussis: Microbiology, Disease, Treatment, and Prevention. J Clin Microbiol Rev 29: 449-86.

Indexed at, Google Scholar, Crossref

2. He Q, Mertsola (2008) Factors contributing to pertussis resurgence. J Future Microbiol 3: 329-339.

Indexed at, Google Scholar, Crossref

3. Carlino C, Zaratti L, Franco E (2013) Old problems and new strategies in the fight against pertussis. Ig Sanita Pubbl 69: 473-480.

Indexed at, Google Scholar, Crossref

4. Valentini D, Ferrara G, Advani R, Hallander HO, Maeurer MJ, et al. (2015) Serum reactome induced by Bordetella pertussis infection and Pertussis vaccines: qualitative differences in serum antibody recognition patterns revealed by peptide microarray analysis. BMC Immunol 16: 40-45.

Indexed at, Google Scholar, Crossref

5. Nitsch-Osuch A, Korzeniewski K, Kuchar E, Zielonka T, Życińska K, et al. (2013) Epidemiological and immunological reasons for pertussis vaccination in adolescents and adults. Respir Physiol Neurobiol 187: 99-103.

Indexed at, Google Scholar, Crossref

6. Souder E, Long SS (2015) Pertussis in the Era of New Strains of Bordetella pertussis. Infect Dis Clin North Am 29: 699-713.

Indexed at, Google Scholar, Crossref

7. Libster R, Edwards KM (2012) Re-emergence of pertussis: what are the solutions? Expert Rev Vaccines. 11: 1331-1346.

Indexed at, Google Scholar, Crossref

8. Sin MA, Zenke R, Rönckendorf R, Littmann M, Jorgensen P, et al. (2009)Pertussis outbreak in primary and secondary schools in Ludwigslust, Germany demonstrating the role of waning immunity. Pediatr Infect Dis J 28: 242-400.

Indexed at, Google Scholar, Crossref

9. Schneider F, Stánitz E, Kalácska J, Tompity T (2009) Whooping cough in an urban high school in Hungary. Conclusions of a local pertussis outbreak. Orv Hetil 150: 1557-1600.

Indexed at, Google Scholar, Crossref

10. Mooi FR (2010) Bordetella pertussis and vaccination: the persistence of a genetically monomorphic pathogen. Infect Genet Evol 10: 36-49.

Indexed at, Google Scholar, Crossref