Vaccines, adjuvants and key factors for mucosal immune response

Abstract

Vaccines are the most effective tool to control infectious diseases, which provoke significant morbidity and mortality rates. Most vaccines are administered through the parenteral route and can elicit a robust systemic humoral response, but they induce a weak T-cell-mediated immunity and are poor inducers of mucosal protection. Considering that most pathogens enter the body through mucosal surfaces, a vaccine that elicits protection in the first site of contact between the host and the pathogen is promising. However, despite the advantages of mucosal vaccines as good options to confer protection on the mucosal surface, only a few mucosal vaccines are currently approved. In this review, we discuss the impact of vaccine administration in different mucosal surfaces; how appropriate adjuvants enhance the induction of protective mucosal immunity and other factors that can influence the mucosal immune response to vaccines.

Induction of systemic, mucosal, and cellular immunity against SARS‐CoV‐2 in mice vaccinated by trans‐airway with a S1 protein combined with a pulmonary surfactant‐derived adjuvant SF‐10

“…Respiratory mucosal immunity plays an important front‐line role against respiratory viral infections. Especially, S‐IgA in the respiratory mucosa protects against invasion of viruses into mucosal cells, resulting in prevention of infection and transmission of pathogens to other individuals 12,25 . Our results demonstrated that S1‐SF‐10‐TA vaccine induced S1‐specific IgG and IgA ASCs in the spleen and lungs (Figure 3) and S1‐specific antibodies in the serum and BALF (Figures 1 and 2A–D), which efficiently inhibited S1/ACE2 binding (Figure 2E–H).…”

“…Since the mucosa is equipped with exclusion systems, namely, the cilia, mucus, and various proteases, against foreign substances including vaccine antigens, 11 the use of vaccines that contain antigen alone is unlikely to produce protective immunity. Thus, for successful mucosal vaccination, live virus vaccines and mucosal adjuvants that enhance the vaccine effects have been developed worldwide 12 . However, the live attenuated vaccines, such as Flumist®, have problems related to their efficacy and safety, and thus, their worldwide use is limited 13 …”

Induction of systemic, mucosal and cellular immunity against SARS-CoV-2 in mice intratracheally vaccinated with a viral S1 protein combined with a pulmonary surfactant-derived adjuvant SF-10

“…Especially, S-IgA in the respiratory mucosa protects against invasion of viruses into mucosal cells, resulting in prevention of infection and transmission of pathogens to other individuals. 12,25 Our results demonstrated that S1-SF-10-IT vaccine induced S1-specific IgG and IgA ASCs in the spleen and lungs (Figure 3) and S1specific antibodies in the serum and BALF (Figure 1, 2A-D), which efficiently inhibited S1/ACE2 binding (Figure 2E-H). The S1-AS03-IM induced S1-specific IgG in the serum and BALF (Figure 2A, B), but not S1-specific IgA in serum and BALF (Figure 2C, D), and S1-specific IgA ASCs in the spleen and lungs (Figure 3B, D).…”

“…Thus, for successful mucosal vaccination, live virus vaccines and mucosal adjuvants that enhance the vaccine effects, have been developed worldwide. 12 However, the live attenuated vaccines, such as Flumist ® , have problems related to their efficacy and safety and thus their worldwide use is limited. 13 To overcome these problems, we reported previously the use of an antigen delivery type adjuvant, 14 pulmonary surfactant (PS)-based compound, surfacten ® , as an effective and safe intranasal mucosal adjuvant for influenza ether-split hemagglutinin vaccine (HAv) and that it enhanced the production of both HAv-specific IgG in serum and S-IgA in the respiratory mucosae of mice and swine.…”

Mucosal Adjuvants Delivered by a Mucoadhesive Patch for Sublingual Administration of Subunit Vaccines

“…Although mucosal vaccines are powerful tools for induction of mucosal immunity [ 1 ], there are still only a few on the market, owing to several technological and biological hurdles impeding the development of efficient formulations [ 2 ]. Among mucosal administration sites, sublingual (SL) mucosa presents an accessible and thin epithelium that has exhibited considerable potential to induce efficient vaccine response in non-human primates [ 3 , 4 ].…”