Julio Gálvez

In vivo quercitrin anti-inflammatory effect involves release of quercetin, which inhibits inflammation through down-regulation of the NF-κB pathway

Quercetin is a common antioxidant flavonoid found in vegetables, which is usually present in glycosylated forms, such as quercitrin (3‐rhamnosylquercetin). Previous in vitro experiments have shown that quercetin exerts a bigger effect than quercitrin in the down‐regulation of the inflammatory response. However, such results have not been reproduced in in vivo experimental models of intestinal inflammation, in which quercetin did not show beneficial effects while its glycosides, quercitrin or rutin, have demonstrated their effectiveness. In this study, we have reported that the in vivo effects of quercitrin in the experimental model of rat colitis induced by dextran sulfate sodium can be mediated by the release of quercetin generated after glycosides cleavage by the intestinal microbiota. This is supported by the fact that quercetin, but not quercitrin, is able to down‐regulate the inflammatory response of bone marrow‐derived macrophages in vitro. Moreover, we have demonstrated that quercetin inhibits cytokine and inducible nitric oxide synthase expression through inhibition of the NF‐κB pathway without modification of c‐Jun N‐terminal kinase activity (both in vitro and in vivo). As a conclusion, our report suggests that quercitrin releases quercetin in order to perform its anti‐inflammatory effect which is mediated through the inhibition of the NF‐κB pathway.

Minocycline: far beyond an antibiotic.

Minocycline is a second‐generation, semi‐synthetic tetracycline that has been in therapeutic use for over 30 years because of its antibiotic properties against both gram‐positive and gram‐negative bacteria. It is mainly used in the treatment of acne vulgaris and some sexually transmitted diseases. Recently, it has been reported that tetracyclines can exert a variety of biological actions that are independent of their anti‐microbial activity, including anti‐inflammatory and anti‐apoptotic activities, and inhibition of proteolysis, angiogenesis and tumour metastasis. These findings specifically concern to minocycline as it has recently been found to have multiple non‐antibiotic biological effects that are beneficial in experimental models of various diseases with an inflammatory basis, including dermatitis, periodontitis, atherosclerosis and autoimmune disorders such as rheumatoid arthritis and inflammatory bowel disease. Of note, minocycline has also emerged as the most effective tetracycline derivative at providing neuroprotection. This effect has been confirmed in experimental models of ischaemia, traumatic brain injury and neuropathic pain, and of several neurodegenerative conditions including Parkinsons disease, Huntingtons disease, amyotrophic lateral sclerosis, Alzheimers disease, multiple sclerosis and spinal cord injury. Moreover, other pre‐clinical studies have shown its ability to inhibit malignant cell growth and activation and replication of human immunodeficiency virus, and to prevent bone resorption. Considering the above‐mentioned findings, this review will cover the most important topics in the pharmacology of minocycline to date, supporting its evaluation as a new therapeutic approach for many of the diseases described herein.

The intestinal anti‐inflammatory effect of quercitrin is associated with an inhibition in iNOS expression

Quercitrin, 3‐rhamnosylquercetin, is a bioflavonoid with antioxidant properties, which exerts anti‐inflammatory activity in experimental colitis. In the present study, different in vivo experiments were performed in order to evaluate the mechanisms of action involved in this effect, with special attention to its effects on proinflammatory mediators, including nitric oxide (NO). Experimental colitis was induced in female Wistar rats by incorporation of dextran sodium sulfate (DSS) in drinking water. Oral treatment of quercitrin (1 or 5 mg kg−1 day−1) to colitic rats ameliorated the evolution of the inflammatory process induced when administered in a preventative dosing protocol. When quercitrin (1 mg kg−1 day−1) was administered on established colitis, it facilitated the recovery of the inflamed mucosa. The beneficial effects exerted by quercitrin were evidenced both histologically and biochemically, and were associated with an improvement in the colonic oxidative status, altered as a consequence of the colonic insult induced by DSS. In addition, a reduction of colonic NO synthase activity was observed, probably related to a decreased expression in the inducible form of the enzyme via downregulation in the colonic activity of the nuclear factor‐κB. Immunohistochemical studies showed that quercitrin treatment reduced macrophage and granulocyte infiltration in the inflamed tissue.

The effects of short-chain fatty acids on colon epithelial proliferation and survival depend on the cellular phenotype

Purpose: The short-chain fatty acids (SCFA) are produced via anaerobic bacterial fermentation of dietary fiber within the colonic lumen. Among them, butyrate is thought to protect against colon carcinogenesis. However, few studies analyze the effects of butyrate, and other SCFA, on normal epithelial cells and on epithelial regeneration during disease recovery. Since there are controversial in vitro studies, we have explored the effects of SCFA on different biological processes. Methods: We used both tumoral (HT-29) and normal (FHC) epithelial cells at different phenotypic states. In addition, we analyzed the in vivo activity of soluble dietary fiber and SCFA production in the proliferation rate and regeneration of intestinal epithelial cells. Results: The effect of butyrate on epithelial cells depends on the phenotypic cellular state. Thus, in nondifferentiated, high proliferative adenocarcinoma cells, butyrate significantly inhibited proliferation while increased differentiation and apoptosis, whereas other SCFA studied did not. However, in normal cells or in differentiated cultures as well as in in vivo studies, the normal proliferation and regeneration of damaged epithelium is not affected by butyrate or SCFA exposure. Conclusion: Although butyrate could exert antiproliferative effects in tumor progression, its production is safe and without consequences for the normal epithelium growth.

A comparative study of the preventative effects exerted by two probiotics, Lactobacillus reuteri and Lactobacillus fermentum, in the trinitrobenzenesulfonic acid model of rat colitis

The intestinal anti-inflammatory effects of two probiotics isolated from breast milk, Lactobacillus reuteri and L. fermentum, were evaluated and compared in the trinitrobenzenesulfonic acid (TNBS) model of rat colitis. Colitis was induced in rats by intracolonic administration of 10 mg TNBS dissolved in 50% ethanol (0.25 ml). Either L. reuteri or L. fermentum was daily administered orally (5 x 10(8) colony-forming units suspended in 0.5 ml skimmed milk) to each group of rats (n 10) for 3 weeks, starting 2 weeks before colitis induction. Colonic damage was evaluated histologically and biochemically, and the colonic luminal contents were used for bacterial studies and for SCFA production. Both probiotics showed intestinal anti-inflammatory effects in this model of experimental colitis, as evidenced histologically and by a significant reduction of colonic myeloperoxidase activity (P<0.05). L. fermentum significantly counteracted the colonic glutathione depletion induced by the inflammatory process. In addition, both probiotics lowered colonic TNFalpha levels (P<0.01) and inducible NO synthase expression when compared with non-treated rats; however, the decrease in colonic cyclo-oxygenase-2 expression was only achieved with L.fermentum administration. Finally, the two probiotics induced the growth of Lactobacilli species in comparison with control colitic rats, but the production of SCFA in colonic contents was only increased when L. fermentum was given. In conclusion, L. fermentum can exert beneficial immunomodulatory properties in inflammatory bowel disease, being more effective than L. reuteri, a probiotic with reputed efficacy in promoting beneficial effects on human health.

Intestinal anti-inflammatory activity of morin on chronic experimental colitis in the rat

Morin, a bioflavonoid with antioxidant properties, shows intestinal anti‐inflammatory activity in the acute phase of the trinitrobenzenesulphonic acid model of rat colitis.

ORAL ADMINISTRATION OF RUTOSIDE CAN AMELIORATE INFLAMMATORY BOWEL DISEASE IN RATS

Rutoside, a flavonoid with antioxidant properties, was tested for acute and chronic antiinflammatory activity in trinitrobenzenesulfonic acid-induced rat colitis. Pretreatment with 10 or 25 mg/kg of rutoside by the oral route reduced colonic damage at 2 days. Several mechanisms can be involved in this activity, and one of these may be related to its ability in preventing glutathione depletion of colitic animals, and this could result in mucosal protection against oxidative insult. When rutoside was tested for 1 and 2 weeks after colitis induction, it was able to promote colonic healing. The chronic effect of the flavonoid was also related with its ability to increase colonic glutathione levels and thus reduce the tissue damage derived from intestinal oxidative stress which characterizes inflammatory colitis.

A comparative study of the preventative effects exerted by three probiotics, Bifidobacterium lactis, Lactobacillus casei and Lactobacillus acidophilus, in the TNBS model of rat colitis.

Aims:  The intestinal anti‐inflammatory effects of three probiotics with immunomodulatory properties, Lactobacillus casei, Lactobacillus acidophilus and Bifidobacterium lactis, were evaluated and compared in the trinitrobenzenesulphonic acid (TNBS) model of rat colitis.

Effect of quercitrin on the early stages of hapten induced colonic inflammation in the rat.

Quercitrin is a flavonoid with antiinflammatory activity in experimental colitis, associated with an antioxidative action and amelioration of water absorption in vivo. However, its mechanism of action is unclear. This study focuses on the effect of quercitrin (1 and 5 mg/kg) in the early stages (24 h) of trinitrobenzene sulfonic acid colitis. Treatment with the flavonoid prevented the increase in colonic malondialdehyde and inhibited nitric oxide synthase and alkaline phosphatase activity but had no significant effects on observable damage. No effect on neutrophil infiltration (myeloperoxidase) was observed. On the other hand, quercitrin exerted complex effects on colonic hydroelectrolytic transport, showing a slight potentiation of water absorption in vivo (5 mg/kg) as well as a normalization of carbachol stimulated electrogenic ionic transport in the proximal colon in vitro (5 mg/kg). It is concluded that the beneficial effects of quercitrin on trinitrobenzene sulfonic acid chronic colitis arise from an early downregulation of the inflammatory cascade that is associated with amelioration of the disturbances in hydroelectrolytic transport.

Role of Th17 Cells in the Pathogenesis of Human IBD.

The gastrointestinal tract plays a central role in immune system, being able to mount efficient immune responses against pathogens, keeping the homeostasis of the human gut. However, conditions like Crohns disease (CD) or ulcerative colitis (UC), the main forms of inflammatory bowel diseases (IBD), are related to an excessive and uncontrolled immune response against normal microbiota, through the activation of CD4+ T helper (Th) cells. Classically, IBD was thought to be primarily mediated by Th1 cells in CD or Th2 cells in UC, but it is now known that Th17 cells and their related cytokines are crucial mediators in both conditions. Th17 cells massively infiltrate the inflamed intestine of IBD patients, where they produce interleukin- (IL-) 17A and other cytokines, triggering and amplifying the inflammatory process. However, these cells show functional plasticity, and they can be converted into either IFN-γ producing Th1 cells or regulatory T cells. This review will summarize the current knowledge regarding the regulation and functional role of Th17 cells in the gut. Deeper insights into their plasticity in inflammatory conditions will contribute to advancing our understanding of the mechanisms that regulate mucosal homeostasis and inflammation in the gut, promoting the design of novel therapeutic approaches for IBD.