Intervention of Isomaltodextrin Mitigates Intestinal Inflammation in a Dextran Sodium Sulfate-Induced Mouse Model of Colitis via Inhibition of Toll-like Receptor-4.

Isomaltodextrin (IMD), a highly branched α-glucan, is a type of resistant starch. Earlier studies have indicated that polysaccharides could prevent inflammation and can be effective in reducing the complications of chronic gastrointestinal diseases such as inflammatory bowel disease (IBD). Therefore, the aim of the present study was to evaluate the anti-inflammatory effect of IMD in dextran sodium sulfate (DSS)-induced colitis in a mouse model. IMD (0.5, 1.0, 2.5, and 5.0% (w/v)) was given orally for 23 days to female Balb/c mice, and then 5% DSS was administered to induce colitis (from day 15 onward to the end of the trial). IMD could not prevent DSS-induced weight loss or colon shortening. However, IMD could reduce inflammatory cytokines, TNF-α and IL-6, in the colon. Gene expression indicated the tendency of IMD to suppress pro-inflammatory cytokines IL-1ß, MCP-1, and IL-17 and to increase an anti-inflammatory cytokine, IL-10. Further study revealed that the anti-inflammatory action of IMD mediates through inhibition of the expression of Toll-like receptor-4.

Adenine attenuates the Ca(2+) contraction-signaling pathway via adenine receptor-mediated signaling in rat vascular smooth muscle cells.

Our previous study demonstrated that adenine (6-amino-6H-purine) relaxed contracted rat aorta rings in an endothelial-independent manner. Although adenine receptors (AdeRs) are expressed in diverse tissues, aortic AdeR expression has not been ascertained. Thus, the aims of this study were to clarify the expression of AdeR in rat vascular smooth muscle cells (VSMCs) and to investigate the adenine-induced vasorelaxation mechanism(s). VSMCs were isolated from 8-week-old male Wistar-Kyoto rats and used in this study. Phosphorylation of myosin light chain (p-MLC) was measured by western blot. AdeR mRNA was detected by RT-PCR. Intracellular Ca(2+) concentration ([Ca(2+)]i) was measured by using Fura-2/AM. Vasorelaxant adenine (10-100 µM) significantly reduced p-MLC by angiotensin II (Ang II, 10 µM) in VSMCs (P < 0.05). We confirmed the expression of aortic AdeR mRNA and the activation of PKA in VSMCs through stimulation of AdeR by adenine by ELISA. Intracellular Ca(2+) concentration ([Ca(2+)]i) measurement demonstrated that adenine inhibits Ang II- and m-3M3FBS (PLC agonist)-induced [Ca(2+)]i elevation. In AdeR-knockdown VSMCs, PKA activation and p-MLC reduction by adenine were completely abolished. These results firstly demonstrated that vasorelaxant adenine can suppress Ca(2+) contraction signaling pathways via aortic AdeR/PKA activation in VSMCs.

Adenine Inhibits TNF-α Signaling in Intestinal Epithelial Cells and Reduces Mucosal Inflammation in a Dextran Sodium Sulfate-Induced Colitis Mouse Model.

Adenine (6-amino-6H-purine), found in molokheiya (Corchorus olitorius L.), has exerted vasorelaxation effects in the thoracic aorta. However, the mode of action of the anti-inflammatory effect of adenine is unclear. Thus, we investigated to clarify the effect of adenine on chronic inflammation of the gastrointestinal tract. In intestinal epithelial cells, adenine significantly inhibited tumor necrosis factor-α-induced interleukin-8 secretion. The inhibition of adenine was abolished under the treatment of inhibitors of adenyl cyclase (AC) and protein kinase A (PKA), indicating the effect of adenine was mediated through the AC/PKA pathway. Adenine (5, 10, and 50 mg/kg BW/day) was administered orally for 14 days to female BALB/c mice, and then 5% dextran sodium sulfate (DSS) was given to induce colitis. Adenine (5 mg/kg BW/day) significantly prevented DSS-induced colon shortening, expression of pro-inflammatory cytokines, and histological damage in the colon. These results suggest that adenine can be a promising nutraceutical for the prevention of intestinal inflammation.

Ferulic acid enhances nitric oxide production through up-regulation of argininosuccinate synthase in inflammatory human endothelial cells.

AIM: In this study, we investigated the protective effect of ferulic acid (FA) on nitric oxide (NO) production in tumor necrosis factor (TNF)-α-stimulated inflammatory human umbilical vein endothelial cells (HUVECs), and elucidated the mechanism(s) involved. MAIN METHODS: The TNF-α-stimulated inflammatory HUVECs were treated with acetylcholine (ACh) and/or FA. NO productions were measured by monitoring nitrite and nitrate using a 2,3-diaminonaphthalene Kit. Expressions of mRNA and proteins were evaluated by RT-PCR and Western blotting, respectively. KEY FINDINGS: FA treatment resulted in a dose-dependent (10-200µM) restoration of ACh-mediated NO production in TNF-α-treated HUVECs, whereas treatment with the FA analogues, coumaric acid, and apocynin resulted in no significant effect. FA treatment had no effect on O2(-) production in TNF-α-stimulated HUVECs. N(G)-monomethyl-l-arginine acetate (a nitric oxide synthase (NOS) inhibitor) and α-methyl-dl-aspartic acid (an argininosuccinate synthase (ASS) inhibitor) counteracted the effects of FA on the NO production. While FA treatment did not significantly affect the protein expression of p-eNOS or eNOS, the protein expression of ASS as well as mRNA expression was restored to normal levels upon exposure to FA in TNF-α-stimulated HUVECs. In nucleus, FA attenuated the increase of nuclear factor-kappa B (NF-κB) expression by TNF-α. SIGNIFICANCE: FA treatment rescues the defect in ACh-induced NO production resulting from TNF-α-stimulation in inflammatory HUVECs. This effect was likely due, in part, to the FA-mediated up-regulation of ASS expression via the suppression of NF-κB inflammatory signaling cascade.