β-hydroxybutyrate (β-HB) exerts anti-inflammatory and antioxidant effects in lipopolysaccharide (LPS)-stimulated macrophages in Liza haematocheila

Poly-beta-hydroxybutyrate (PHB) can be hydrolyzed to beta-hydroxybutyrate (beta-HB) in the intestinal tract of animals, and dietary PHB supplementation could enhance the immunity and disease resistance of aquatic animals. Antioxidant system is responsive to PHB stimuli via MAPK/PI3K-Akt/TNF/NF-kappa B/TCR/TLR signaling pathways. However, the precise immunopotentiation mechanism needs further study. In this study, macrophages from spleen in Liza haematocheila was used to study the effect of beta-HB on cell viability and antioxidant function to illustrate the immunopotentiation mechanism of PHB. The results showed that beta-HB (100 mu g/mL) promoted the viability of macrophages and balanced the production of reactive oxygen species, but inhibited the excessive production of intracellular nitric oxide. In order to further explore the immunopotentiation mechanism of beta-HB, LPS (100 mu g/mL) was used to induce the inflammation and investigated the inhibitory effect of beta-HB on inflammation. The results showed that LPS could induce inflammation successfully, and beta-HB exerted antiinflammatory and antioxidant effects in LPS-stimulated macrophages. Compared with LPS stimuli alone, the expression of anti-inflammatory genes NF-kappa BIA, MAP3K8 and TLR5 in beta-HB pretreatment group was upregulated, and the expression of pro-inflammatory genes TNFSF6, TNF-alpha, PI3K, NF-kappa B and TLR1 downregulated. It suggested that ss-HB inhibited the inflammatory response by up-regulation of anti-inflammatory genes such as NF-kappa BIA, thereby enhancing the immunity of the body.