Immunomodulatory role of outer membrane vesicles of Shigella in mouse model

In our previous studies, we discussed the protective efficacy of the two types of vaccine formulation namely SOMVs (single-serotype outer membrane vesicles) and MOMVs (multi-serotype outer membrane vesicles). Here, we compared the immunogenic roles of these two types of formulations and also studied general immunomodulation by Shigella OMVs in adult BALB/c mice. The production of various pro-inflammatory (TNF-α, IL-1β, IL-6, IL-12, IL-18, IFN-γ) and anti-inflammatory (IL-4 and IL-10) cytokine profile were assessed by in vivo, ex vivo and in vitro studies. MOMVs treated mice showed significantly enhanced cytokine production compared to SOMVs treated mice. MOMVs treatment has also upregulated iNOS mRNA synthesis in macrophages. Overall the OMVs of Shigella were found to show a mixed Th1/Th2 response and maintain the balance between pro-inflammation and anti-inflammation in mice. This will be crucial in the development of the next generation OMVs based vaccine against shigellosis.