PepT1-Knockout Mice Harbor a Protective Metabolome Beneficial for Intestinal Wound Healing

Genetic knockout (KO) of peptide transporter-1 (PepT1) protein is known to provide resistance to acute colitis and colitis-associated cancer (CAC) in mouse models. However, it was unclear which molecule(s) or pathway(s) formed the basis for these protective effects. Recently, we demonstrated that the PepT1-/- microbiota is sufficient to protect against colitis and CAC. Given that PepT1 KO alters the gut microbiome and thereby changes the intestinal metabolites that are ultimately reflected in the feces, we investigated the fecal metabolites of our PepT1 KO mice. Using a liquid chromatography-mass spectrometry (LC-MS)-based untargeted-metabolomics technique, we found that the fecal metabolites were significantly different between the KO and normal wild-type (WT) mice. Among the altered fecal metabolites, tuberonic acid (TA) was seven-fold higher in KO mouse feces than in WT mouse feces. Accordingly, we studied whether the increased TA could direct an anti-inflammatory effect. Using in vitro models, we discovered that TA not only prevented lipopolysaccharide (LPS)-induced inflammation in macrophages but also improved the epithelial cell healing processes. Our results suggest that TA, and possibly other fecal metabolites, play a crucial role in the pathway(s) associated with the anti-colitis effects of PepT1 KO.

Bioactive Compounds in Moringa oleifera Lam. Leaves Inhibit the Pro-Inflammatory Mediators in Lipopolysaccharide-Induced Human Monocyte-Derived Macrophages

Moringa oleifera (MO) is an important plant for traditional medicine. The present study aimed to identify the MO active phytochemical compounds for their ability against inflamed macrophages. An ethyl acetate extract fraction of MO was fractionation by flash column chromatography. Human macrophages were stimulated by Lipopolysaccharide and then treated with fractions of MO to examine their anti-inflammatory activity and cellular mechanism. The active fractions were analyzed by liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometer (LC-ESI-QTOF-MS). MO treated cells showed a decreased production of pro-inflammatory mediator in response to lipopolysaccharide. This was evident at both mRNA and protein levels. The study revealed that MO suppressed mRNA expression of IL-1, IL-6, TNF-α, PTGS2, NF-κB (P50), and RelA. Furthermore, the extract effectively inhibited the expression of inflammatory mediators, including IL-6, TNF-α, and cyclooxygenase-2. Interestingly, the effect of MO inhibited phosphorylation of IκB-α and the ability to reduce expression of the nuclear factor (NF)-κB p65, suppressing its nuclear translocation. Moreover, LC-ESI-QTOF-MS analysis of the MO active fraction revealed seven compounds, namely 3,4-Methyleneazelaic acid, (2S)-2-phenylmethoxybutane-1,4-diol, (2R)-2-phenylmethoxybutane-1, 4-diol, γ-Diosphenol, 2,2,4,4-Tetramethyl-6-(1-oxobutyl)-1,3,5-cyclohexanetrione, 3-Hydroxy-β-ionone, and Tuberonic acid. Our findings highlight the ability of MO compounds to inhibit inflammation through regulation of the NF-κB pathway.