Short-chain
fatty acids (SCFAs) are gut microbial metabolic derivatives
produced during the fermentation of ingested complex carbohydrates.
SCFAs have been widely regarded to have a potent anti-inflammatory
and neuro-protective role and have implications in several disease
conditions, such as, inflammatory bowel disease, type-2 diabetes,
and neurodegenerative disorders. Japanese encephalitis virus (JEV),
a neurotropic flavivirus, is associated with life threatening neuro-inflammation
and neurological sequelae in infected hosts. In this study, we hypothesize
that SCFAs have potential in mitigating JEV pathogenesis. Postnatal
day 10 BALB/c mice were intraperitoneally injected with either a SCFA
mixture (acetate, propionate, and butyrate) or PBS for a period of
7 days, followed by JEV infection. All mice were observed for onset
and progression of symptoms. The brain tissue was collected upon reaching
terminal illness for further analysis. SCFA-supplemented JEV-infected
mice (SCFA + JEV) showed a delayed onset of symptoms, lower hindlimb
clasping score, and decreased weight loss and increased survival by
3 days (p < 0.0001) upon infection as opposed
to the PBS-treated JEV-infected animals (JEV). Significant downregulation
of inflammatory cytokines TNF-α, MCP-1, IL-6, and IFN-Υ
in the SCFA + JEV group relative to the JEV-infected control group
was observed. Inflammatory mediators, phospho-NF-kB (P-NF-kB) and
iba1, showed 2.08 ± 0.1 and 3.132 ± 0.43-fold upregulation
in JEV versus 1.19 ± 0.11 and 1.31 ± 0.11-fold in the SCFA
+ JEV group, respectively. Tissue section analysis exhibited reduced
glial activation (JEV group42 ± 2.15 microglia/ROI; SCFA
+ JEV group27.07 ± 1.8 microglia/ROI) in animals that
received SCFA supplementation prior to infection as seen from the
astrocytic and microglial morphometric analysis. Caspase-3 immunoblotting
showed 4.08 ± 1.3-fold upregulation in JEV as compared to 1.03
± 0.14-fold in the SCFA + JEV group and TUNEL assay showed a
reduced cellular death post-JEV infection (JEV-6.4 ± 1.5 cells/ROI
and SCFA + JEV-3.7 ± 0.73 cells/ROI). Our study critically contributes
to the increasing evidence in support of SCFAs as an anti-inflammatory
and neuro-protective agent, we further expand its scope as a potential
supplementary intervention in JEV-mediated neuroinflammation.