Gut microbial metabolites butyrate and acetate limit Zika virus replication and associated ocular manifestations via the G-protein coupled receptor 43/FFAR2
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Short-chain fatty acids (SCFAs) are gut microbial metabolites produced by gut microbiota from dietary fiber. SCFAs have shown both pro- and anti-viral roles among different viruses, and are known to regulate immune functions during infections. However, their role against the Zika virus (ZIKV) in general and ocular infection, in particular, has never been investigated. In the present study, we aimed to examine the role of three SCFA derivatives: phenylbutyrate (PBA), sodium butyrate (NaB), and sodium acetate (NaAC), on ZIKV replication and associated ocular complications using primary human trabecular meshwork cells (HTMCs) and an IFNAR1-deficient mouse model of ocular infection. Our findings reveal that PBA and NaAc treatment dramatically suppressed the ZIKV replication in HTMCs. NaB showed a slightly less effect than PBA and NaAc. PBA and NaAc treatment significantly attenuated the ZIKV-induced inflammatory cytokine, interferons, and interferon-stimulated genes response via antagonizing the RIG-I/NFκB/MAPKs/STAT1-3 signaling pathways. We discovered that ZIKV induces the expression of free fatty acid receptor 2 (FFAR2)/ GPR43 in HTMCs, which is further potentiated by PBA/NaAc. Pharmacological inhibition of FFAR2 abrogated the protective abilities of PBA/NaAc and significantly increased viral replication. Blocking FFAR2 receptors promoted ZIKV-induced cell death, which was suppressed by PBA and NaAc. Mechanistically, butyrate and acetate inhibited ZIKV binding and cellular entry and inactivated the virus before internalization. PBA and NaAc treatment in mice attenuated the ZIKV-induced ocular manifestations (intraocular pressure, RPE/retinal atrophy, and anterior segment inflammation), which was abrogated by FFAR2 inhibition. Collectively, our findings indicate that SCFA treatment is an effective approach to limit ZIKV replication and associated ocular damage and may be worth exploring as a means to treat or prevent ZIKV-induced ocular complications in humans.
Importance
ZIKV is known to cause severe ocular manifestations in in-utero exposed infants; however, the molecular mechanisms of ZIKV-induced ocular complications remain unknown. SCFAs have demonstrated both pro- and anti-viral roles against different viruses; however, their role against ZIKV is unknown. We showed that SCFAs butyrate and acetate suppress ZIKV transmission and associated ocular complications. The anti-ZIKV activity of these SFACs is mediated via FFAR2, and pharmacological inhibition of FFAR2 promotes ZIKV-induced inflammatory and cell death responses, as well as ocular malformations.
