Effect of intrarectal prostaglandin E2 analogue (enprostil) on trinitrobenzenesulphonic acid-induced colitis in rats

Flos lonicerae flavonoids attenuate experimental ulcerative colitis in rats via suppression of NF-κB signaling pathway

This study sought to isolate active Flos lonicerae flavonoids and evaluate their anti-oxidative and anti-inflammatory effects as well as investigate the molecular mechanistic action of these flavonoids in the rat model of ulcerative colitis (UC). Total flavonoids and three flavonoids (hyperoside, lonicerin, and luteolin) were isolated from honeysuckle and purified via column purification. Rat model of UC was established via 2,4,6-trinitrobenzene sulfonic acid (TNBS) intoxication. The anti-oxidative and anti-inflammatory effects of the three flavonoids against TNBS-induced UC were evaluated by measuring appropriate biomarkers via assay kit. The effects of hyperoside, lonicerin, and luteolin on the regulation of nuclear factor-kappa B (NF-κB) pathway were investigated using Western blot (WB) and real-time polymerase chain reaction (RT-PCR) while their protective effects on UC were also elucidated. Pretreatment with flavonoids (hyperoside, lonicerin, and luteolin at 25-100 mg/kg) and sulfasalazine (SSZ, positive control at 100 mg/kg) substantially attenuated TBNS-induced UC. Also, the flavonoids significantly reduced the levels of respective serum oxidative and proinflammatory markers such as superoxide dismutase (SOD), myeloperoxidase (MPO), malondialdehyde (MDA), prostaglandins E2 (PGE2), tumor necrosis factor-alpha (TNF-α), interleukin-beta (IL-β), and C-reactive protein (CRP). In addition, the flavonoids remarkably inhibited the expression of NF-κB signaling pathway. F. lonicerae flavonoids (hyperoside, lonicerin, and luteolin) demonstrated potent anti-UC activities in TBNS-induced UC rat model via anti-oxidative and anti-inflammatory effects through the inhibition of NF-κB signaling pathway.

Misoprostol protects mice against severe Clostridium difficile infection and promotes recovery of the gut microbiota after antibiotic perturbation

Clostridium difficile infection (CDI) is one of the most common nosocomial infections worldwide and an urgent public health threat. Epidemiological and experimental studies have demonstrated an association between nonsteroidal anti-inflammatory drug (NSAID) exposure and enhanced susceptibility to, and severity of, CDI. NSAIDs target cyclooxygenase enzymes and inhibit the production of prostaglandins (PGs), but the therapeutic potential of exogenous introduction of PGs for the treatment of CDI has not been explored. In this study, we report that treatment with the FDA-approved stable PGE₁ analogue, misoprostol, protects mice against C. difficile-associated mortality, intestinal pathology, and CDI-mediated intestinal permeability. Furthermore, we report that the effect of misoprostol on the gastrointestinal tract contributes to increased recovery of the gut microbiota following antibiotic perturbation. Together, these data implicate PGs as an important host-factor associated with recovery to C. difficile-associated disease and demonstrate the potential for misoprostol in the treatment of CDI. Further studies to explore the safety and efficacy of misoprostol treatment of CDI in humans is needed.

Antagonizing arachidonic acid-derived eicosanoids reduces inflammatory Th17 and Th1 cell-mediated inflammation and colitis severity

During colitis, activation of two inflammatory T cell subsets, Th17 and Th1 cells, promotes ongoing intestinal inflammatory responses. n-6 polyunsaturated fatty acid- (PUFA-) derived eicosanoids, such as prostaglandin E2 (PGE2), promote Th17 cell-mediated inflammation, while n-3 PUFA antagonize both Th17 and Th1 cells and suppress PGE2 levels. We utilized two genetic mouse models, which differentially antagonize PGE2 levels, to examine the effect on Th17 cells and disease outcomes in trinitrobenzene sulfonic acid- (TNBS-) induced colitis. Fat-1 mice contain the ω3 desaturase gene from C. elegans and synthesize n-3 PUFA de novo, thereby reducing the biosynthesis of n-6 PUFA-derived eicosanoids. In contrast, Fads1 Null mice contain a disrupted Δ5 desaturase gene and produce lower levels of n-6 PUFA-derived eicosanoids. Compared to Wt littermates, Fat-1 and Fads1 Null mice exhibited a similar colitic phenotype characterized by reduced colonic mucosal inflammatory eicosanoid levels and mRNA expression of Th17 cell markers (IL-17A, RORγτ, and IL-23), decreased percentages of Th17 cells and, improved colon injury scores (P ≤ 0.05). Thus, during colitis, similar outcomes were obtained in two genetically distinct models, both of which antagonize PGE2 levels via different mechanisms. Our data highlight the critical impact of n-6 PUFA-derived eicosanoids in the promotion of Th17 cell-mediated colonic inflammation.

Colonic treatments and targets: issues and opportunities

The colon provides a plethora of therapeutic opportunities. There are multiple disease targets, drug molecules, and colon-specific delivery systems to be explored. Clinical studies highlight the potential for systemic delivery via the colon, and the emerging data on the levels of cell membrane transporters and metabolic enzymes along the gut could prove advantageous for this. Often efflux transporters and metabolic enzyme levels are lower in the colon, suggesting a potential for improved bioavailability of drug substrates at this site. The locoregional distribution of multiple metabolic enzymes (including cytochromes), efflux transporters (including P-glycoprotein and breast cancer resistance proteins), and influx transporters (including the solute carrier family) along the intestine is summarized. Local delivery to the colonic mucosa remains a valuable therapeutic option. New therapies that target inflammatory mediators could improve the treatment of inflammatory bowel disease, and old and new anticancer molecules could, when delivered topically, prove to be beneficial adjuncts to the current systemic or surgical treatments. New issues such as pharmacogenomics, chronotherapeutics, and the delivery of prebiotics and probiotics are also discussed in this review. Targeting drugs to the colon utilizes various strategies, each with their advantages and flaws. The most promising systems are considered in the light of the physiological data which influence their in vivo behavior.