Benzoic acid as a dietary supplement mitigates inflammation and intestinal dysfunction in acute ETEC-infected mice without adverse effects in healthy mice

Abstract

Benzoic acid is naturally occurring in fruits and is also commercially synthesized as an additive in the food, feed, and pharmaceutical industries. This study investigated the effects of benzoic acid as a dietary supplement on inflammation and intestinal integrity in acute ETEC-infected or healthy mice. Thirty-six BALB mice were allocated into 3 groups of 12 mice each for a 16-day feeding trial. Group 1 mice were fed basal diet, and 6 mice were sacrificed and 6 mice were intraperitoneally injected with PBS on day 15. Group 2 and 3 mice were fed basal diet and 0.6% benzoic acid diet, respectively, and half mice of each group were sacrificed and the others were intraperitoneally injected with ETEC on day 15. The results show that benzoic acid had no adverse effects on healthy mice regarding growth, organ indices, inflammation, intestinal morphology, barrier function, and caecal short-chain fatty acid levels. Importantly, benzoic acid reduced inflammation in ETEC-infected mice, as indicated by decreased serum IL-1β, TNF-α, and INF-γ levels and increased jejunal TLR-2 and MyD88 mRNA expression. Besides, benzoic acid enhanced intestinal function in ETEC-infected mice by increasing jejunal VH and VH/CD, elevating jejunal Occludin mRNA level, decreasing serum D-lactate and DAO levels, and increasing caecal acetic acid level. The16s rRNA sequencing shows that benzoic acid altered the β-diversity of ETEC-infected mice and increased the abundance of Erysipelotrichaceae, Faecalibaculum, and Turicibacter in their gut microbiota. The Spearman correlation analysis further reveals that the protective effects of benzoic acid against ETEC infection are closely linked to specific gut microbiota, namely Erysipelotrichaceae, Faecalibaculum, Bifidobacterium, and Limosilactobacillus. Collectively, benzoic acid could serve as a safe dietary supplement for healthy mice and can alleviate inflammation and intestinal dysfunction in mice with acute ETEC infection.