Fig. 7
Role of the bacterial symbiosis factor PSA in preventing viral encephalitis. HSV infection of susceptible 129 WT mice provokes excessive production of neutrophils (PMN) and Ly6Chigh inflammatory monocytes (IM) in the bone marrow that invade the brainstem in massive numbers resulting in fatal HSV encephalitis (HSE), despite antiviral treatment from day 4 pi. The bacterial symbiosis factor, PSA given orally is bound by B cells/CD138+ plasmablasts (PB) in the small intestine, which induces IL-10 and IFNγ production by regulatory CD4 and CD8 T cells resulting in the suppression of pathogenic inflammatory myeloid cells concomitant with the induction of IFNγ inducible chemokines in the BS. This novel study reveals the immunomodulatory potential of PSA in protecting from lethal viral infections of the CNS in combination with an antiviral. Cells involved in this protective mechanism are shown in the key. Inhibitory pathways indicated by red blocking arrows
