Investigation into the anti-inflammatory mechanism of coffee leaf extract in LPS-induced Caco-2/U937 co-culture model through cytokines and NMR-based untargeted metabolomics analyses

In this study, lipopolysaccharide (LPS)-induced Caco-2/U937 co-culture was used to investigate the anti-inflammatory mechanism of coffee leaf extract (CLE). HPLC analysis found that 5-caffeoylquinic acid (5-CQA) and epicatechin were degraded by 96.66 % and 85.35 %, respectively after 24 h incubation, while rutin and trigonelline remained unchanged. The absorption efficiency of 4,5-dicaffeoylquinic acid (4,5-diCQA) and mangiferin were higher than the other phytochemicals, reaching 46.90 % and 37.65 %, respectively. CLE significantly inhibited TNF-α, IL-1β, and IL-8 produced by LPS-induced U937 cells in the basolateral side as well as IL-8 produced by apical Caco-2 cells, thereby inhibiting the intestinal monolayer leakage evidenced by the increase of transepithelial electrical resistance (TEER) values. CLE ameliorated some of the LPS-induced impaired cellular immunometabolism, including amino acid and energy metabolisms. Our study indicated that CLE inhibited the pro-inflammatory cytokines and regulated the metabolites in the co-culture system, thus recovering the disrupted intestinal monolayer caused by inflammation.