Mucosal transmission is the prevalent route used by infectious agents to invade host organism and secretory
immunity is the main line of defence, as it generates secretory IgA that can block pathogens at the mucosal surface. MEC/
CCL28 (CCL28) binds to CCR3 and CCR10 and recruits IgA-secreting plasma cells (IgA-ASCs) in the mucosal lamina propria.
Virus-like Particles (VLPs) are a novel vaccine approach based on non-pathogenic particles that mimic the structure of virus
particles with effective induction of both arms of the immune response. The suitability of CCL28 as an adjuvant for the elicitation
of optimal innate and acquired mucosal and systemic immunity was assessed in mice using three different VLP mucosal viral
infection models: HIV-1, Influenza A virus (H7N1) and HPV-16.
Materials and methods:
Balb/c mice were immunized intramuscularly with a prime-boost regime based on VLP containing
either gp160 from HIV-1 clade B, Influenza A H7N1 hemagglutinin or HPV-16 L1 protein in the presence/absence of CCL28
and of the parental control CCL19. Flow citometry evaluation of CCR3 and CCR10 expression was performed on purified
splenocytes. Antigen-specific Th1 and Th2 cytokine production was performed on splenocytes and either colon, lungs or uterine
cervix, depending on the dominant site of infection within mucosal tissues, whereas antigen-specific IgG and IgA antibodies were
evaluated in sera and mucosal secretions by ELISA. Immune sera and mucosal secretions were tested for ex vivo neutralization
activity against either HIV-1 subtype B and C strains, Influenza A virus or HPV-16. IgA-ASCs recruitment at the mucosal level
was verified with immune-histochemistry analyses.
The following immune parameters were significantly augmented in VLP-CCL28 mice compared to either VLP-CCL19,
VLP alone, CCL28-alone, CCL19-alone or saline mice: 1) the percentage and the surface density (MFI) of CCR3 and CCR10
on CD19+ splenocytes; 2) antigen-specific IFN-γ, IL-4 and IL-5 production in splenocytes and mucosal specimens; 3) total IgA
titers in sera and in mucosal secretions; 4) antigen-specific IgG and IgA titers in sera and in mucosal secretions. Sera and mucosal
secretions from VLP-CCL28 mice showed a significantly augmented neutralizing activity against homologous and heterologous
viruses compared to controls. Furthermore, IgA-ASCs were significantly increased in either rectum, lungs or uterine cervix of
CCL28 used as an adjuvant has a robust immunomodulatory effect on potentially beneficial mucosal and systemic
immune responses. These findings suggest that CCL28 could play a useful role in increasing the efficacy of preventive vaccines
for mucosally transmitted viral infections.
Peer Reviewed Journals
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals