Mucin secretory action of capsaicin prevents high fat diet-induced gut barrier dysfunction in C57BL/6 mice colon

Cutaneous Application of Capsaicin Cream Reduces Clinical Signs of Experimental Colitis and Repairs Intestinal Barrier Integrity by Modulating the Gut Microbiota and Tight Junction Proteins

Capsaicin, a pungent compound in chili peppers, is described as having potent anti-inflammatory, antioxidant, and antimicrobial properties. It is also described as a potential modulator of the immune system and intestinal microbiota. Oral or rectal administration of capsaicin has been studied to treat or prevent colitis. However, those vias are often not well accepted due to the burning sensation that capsaicin can cause. Our objective was to evaluate whether the application of capsaicin skin creams (0.075%) would be effective in improving inflammation and epithelial barrier function as well as the composition of the gut microbiota in a model of mild colitis induced by dextran sulfate sodium (1.5%). The results showed that the cutaneous application of capsaicin reversed weight loss and decreased colon shortening and diarrhea, all typical signs of colitis. There was also an improvement in the intestinal epithelial barrier, preserving proteins from tight junctions. We also evaluated the biodistribution of 99mtechnetium-radiolabeled capsaicin (99mTc-CAPS) applied to the back skin of the animals. We found significant concentrations of 99 mTc-Cap in the colon and small intestine after 2 and 4 h of administration. In addition, there was an increased expression of capsaicin receptor TRPV1 in the colon. Moreover, animals with colitis receiving cutaneous capsaicin presented a better short-chain fatty acid profile and increased levels of SIgA, suggesting increased microbiota diversity. In conclusion, our work opens avenues for further studies to better understand capsaicin's potential benefits and mechanisms in addressing colitis through cutaneous application.

Oyster Peptides Ameliorate Dextran Sulfate Sodium-Induced Ulcerative Colitis via Modulating the Gut Microbiota and Inhibiting the TLR4/NF-κB Pathway

Ulcerative colitis (UC) is an inflammatory bowel disease with an increasing prevalence year over year, and the medications used to treat patients with UC clinically have severe side effects. Oyster peptides (OPs) have anti-inflammatory and antioxidant properties as functional foods that can alleviate a wide range of inflammatory conditions. However, the application of oyster peptides in ulcerative colitis is not well studied. In this work, an animal model of acute colitis was established using 3% dextran sulfate sodium (DSS), and the impact of OP therapy on colitis in mice was examined. Supplementing with OPs prevented DSS-induced colitis from worsening, reduced the expression of oxidative stress and inflammatory markers, and restored the intestinal barrier damage caused by DSS-induced colitis in mice. The 16S rDNA results showed that the OP treatment improved the gut microbiota structure of the UC mice, including increasing microbial diversity, increasing beneficial bacteria, and decreasing harmful bacteria. In the UC mice, the OP therapy decreased the relative abundance of Family_XIII_AD3011_group and Prevotella_9 and increased the relative abundance of Alistipes. In conclusion, OP treatment can inhibit the TLR4/NF-κB pathway and improve the intestinal microbiota in UC mice, which in turn alleviates DSS-induced colitis, providing a reference for the treatment of clinical UC patients.

Large Yellow Tea Polysaccharide Alleviates HFD-Induced Intestinal Homeostasis Dysbiosis via Modulating Gut Barrier Integrity, Immune Responses, and the Gut Microbiome

Long-term high-fat diet (HFD) will induce dysbiosis and a disturbance of intestinal homeostasis. Large yellow tea polysaccharide (LYP) has been shown to improve obesity-associated metabolic disease via modulation of the M2 polarization. However, the contribution of LYP to intestinal barrier impairment and improvement mechanisms in obesity caused by an HFD are still not clear. In this study, we evaluated the impacts of LYP on the mucosal barrier function and microbiota composition in HFD-feeding mice. Results exhibited that dietary LYP supplement could ameliorate the physical barrier function via maintaining intestinal mucosal integrity and elevating tight-junction protein production, strengthen the chemical barrier function via up-regulating the levels of glucagon-like peptide-1 and increasing mucin-producing goblet cell numbers, and enhance the intestinal immune barrier function though suppressing immune cell subsets and cytokines toward pro-inflammatory phenotypes. Moreover, LYP reshaped the constitution and metabolism of intestinal flora by enriching probiotics that produce short-chain fatty acids. Overall, LYP might be used as a critical regulator of intestinal homeostasis to improve host health by promoting gut barrier integrity, modulating intestinal immune response, and inhibiting bowel inflammation.

A quinoa peptide protects impaired mucus barriers in colitis mice by inhibiting NF-κB-TRPV1 signaling and regulating the gut microbiota

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions that lead to the disruption of the colonic mucus barrier. Quinoa has a well-balanced profile of essential amino acids and exhibits excellent anti-inflammatory effects. We recently explored the beneficial effects and relevant mechanisms of a novel quinoa peptide TPGAFF on impaired mucus barriers in mice with chemically induced colitis. Our findings demonstrated that TPGAFF, administered in low and high doses for 28 days, effectively attenuated the pathological phenotype and reduced intestinal permeability in colitis mice. TPGAFF demonstrated its protective abilities by restoring the impaired mucus barrier, inhibiting the activation of inflammatory signaling and reducing inflammatory cytokine levels. Moreover, TPGAFF positively influenced the composition of the gut microbiota by reducing inflammation-related microbes. Additionally, TPGAFF inhibited the activation of TRPV1 nociceptor and decreased the levels of neuropeptides. Conclusively, our results indicated that oral administration of TPGAFF may be an optional approach for the treatment of mucus barrier damage.

Are We Ready to Recommend Capsaicin for Disorders Other Than Neuropathic Pain?

Capsaicin, a lipophilic, volatile compound, is responsible for the pungent properties of chili peppers. In recent years, a significant increase in investigations into its properties has allowed the production of new formulations and the development of tools with biotechnological, diagnostic, and potential therapeutic applications. Most of these studies show beneficial effects, improving antioxidant and anti-inflammatory status, inducing thermogenesis, and reducing white adipose tissue. Other mechanisms, including reducing food intake and improving intestinal dysbiosis, are also described. In this way, the possible clinical application of such compound is expanding every year. This opinion article aims to provide a synthesis of recent findings regarding the mechanisms by which capsaicin participates in the control of non-communicable diseases such as obesity, diabetes, and dyslipidemia.

Ion channels and transporters regulate nutrient absorption in health and disease

Ion channels and transporters are ubiquitously expressed on cell membrane, which involve in a plethora of physiological process such as contraction, neurotransmission, secretion and so on. Ion channels and transporters is of great importance to maintaining membrane potential homeostasis, which is essential to absorption of nutrients in gastrointestinal tract. Most of nutrients are electrogenic and require ion channels and transporters to absorb. This review summarizes the latest research on the role of ion channels and transporters in regulating nutrient uptake such as K+ channels, Ca2+ channels and ion exchangers. Revealing the mechanism of ion channels and transporters associated with nutrient uptake will be helpful to provide new methods to diagnosis and find potential targets for diseases like diabetes, inflammatory bowel diseases, etc. Even though some of study still remain ambiguous and in early stage, we believe that ion channels and transporters will be novel therapeutic targets in the future.

Capsazepine-Induced Altered Colonic Mucosal Health Limits Isomalto-oligosaccharide Action in High-Fat Diet-Fed C57BL/6J Mice

The present study sought to understand the effects of a combination of altered colonic mucosal health (intrarectal capsazepine administration) and high-fat diet (HFD) administration in mice. Furthermore, we also studied whether this combination prevents protective actions of dietary prebiotic, isomaltooligosaccharides. We studied the alterations in intestinal permeability, histological and transcriptional changes, short-chain fatty acid (SCFA) concentrations, and gut microbial abundance. Capsazepine (CPZ) was administered rectally twice a day along with HFD feeding. Following confirmation of CPZ action (loss of TRPA1 and TRPV1-associated nocifensive behavior), the intrarectal dose of CPZ was reduced to once in 2 days up to 8 weeks. Simultaneous intrarectal administration of CPZ exacerbated the HFD (8 weeks feeding)-induced damage to mucosal lining, intestinal permeability, tight junction protein expression, SCFA levels, and gut bacterial abundances. This higher degree of mucosal damage and pathological alteration in colonic mucosa prevented the previously reported protective actions of isomaltooligosaccharides as a prebiotic in HFD-fed mice. Overall, we present evidence that colonic precondition (gut permeability and mucosal lining) is an important factor in determination of HFD-induced changes in the colon, and success of diet-associated interventions (dietary fibers, pre/probiotics, etc.) is dependent on it.

A special polysaccharide hydrogel coated on Brasenia schreberi: preventive effects against ulcerative colitis via modulation of gut microbiota

Ulcerative colitis (UC) is a growing health concern in humans, but it can be prevented by using special dietary strategies. Young stems and leaves of Brasenia schreberi (BS) are coated with a special polysaccharide hydrogel (BS mucilage) which can be beneficial for colon health. The aim of this study was to investigate the preventive effects of BS mucilage against UC in a DSS-treated mouse model. Although containing only 0.3% solid content, our research showed that BS mucilage effectively attenuated the disease activity index (DAI) and the spleen index and downregulated IL-1β, IL-18, IL-6 and CAT mRNA levels in DSS-treated mice, which is a promising UC alleviation function. Additionally, BS mucilage also improved the propionate and butyrate levels in mouse feces and alleviated the imbalanced gut microbiota induced by DSS. The abundance of pro-inflammatory and colorectal cancer related bacteria, such as Prevotella, Ruminococcus, Acutalibacter and Christensenella, was decreased by BS mucilage feeding, whereas the abundance of anti-inflammatory and SCFA-producing bacteria including Alistipes and Odoribacter was increased. In conclusion, the current study shows that the daily consumption of BS mucilage could be an effective way to prevent UC in mice, via modulation of gut microbiota.

Orchestration of MUC2 - The key regulatory target of gut barrier and homeostasis: A review

The gut mucosa of human is covered by mucus, functioning as a crucial defense line for the intestine against external stimuli and pathogens. Mucin2 (MUC2) is a subtype of secretory mucins generated by goblet cells and is the major macromolecular component of mucus. Currently, there is an increasing interest on the investigations of MUC2, noting that its function is far beyond a maintainer of the mucus barrier. Moreover, numerous gut diseases are associated with dysregulated MUC2 production. Appropriate production level of MUC2 and mucus contributes to gut barrier function and homeostasis. The production of MUC2 is regulated by a series of physiological processes, which are orchestrated by various bioactive molecules, signaling pathways and gut microbiota, etc., forming a complex regulatory network. Incorporating the latest findings, this review provided a comprehensive summary of MUC2, including its structure, significance and secretory process. Furthermore, we also summarized the molecular mechanisms of the regulation of MUC2 production aiming to provide developmental directions for future researches on MUC2, which can act as a potential prognostic indicator and targeted therapeutic manipulation for diseases. Collectively, we elucidated the micro-level mechanisms underlying MUC2-related phenotypes, hoping to offer some constructive guidance for intestinal and overall health of mankind.

Modified cereal bran (MCB) from finger millet, kodo millet, and rice bran prevents high-fat diet-induced metabolic derangements

Cereal bran consumption improves gastrointestinal and metabolic health. Unprocessed cereal brans have a limited shelf-life and contain anti-nutrient phytochemicals. In the present study, lipids and antinutrients (flavonoids, tannin, and polyphenol) were removed from finger millet, kodo millet and rice bran using chemo-enzymatic processing. The thus-obtained modified cereal brans (MCBs) were evaluated for their potential in preventing high fat diet (HFD)-induced obesity. C57BL/6 mice were fed a HFD or a HFD supplemented with 10% w/w modified finger millet bran (mFMB), modified kodo millet bran (mKMB), modified rice bran (mRB), or a combination of the modified brans (1 : 1 : 1) for twelve weeks. The MCBs reduced HFD-induced body weight gain, improved glucose homeostasis, decreased the Firmicutes/Bacteroidetes ratio, and increased the short chain fatty acid (SCFA) levels in the cecum. Liver dyslipidemia, oxidative stress, inflammation, visceral white adipose tissue (vWAT) hypertrophy, and lipolysis were also prevented by the MCBs. Among the individual MCBs, mRB showed a greater effect in preventing HFD-induced increase in the inflammatory cytokines (IL-6, TNF-α, and LPS) than mFMB and mKMB. mFMB and mKMB supplementation more significantly restored the relative abundance of Akkermansia muciniphila and butyrate-producing genera such as Lachnospiraceae, Eubacterium, and Ruminococcus than mRB. Ex vivo gut permeability assay, immunohistochemistry of tight junction proteins, and gene expression analysis in the colon revealed that the combination of three brans was better in preventing HFD-induced leaky gut in comparison to the individual brans. Hierarchical clustering analysis showed that the combination group was clustered closest to the NPD group, suggesting an additive effect. Our study implies that a combination of mFMB, mKMB, and mRB could be used as a nutraceutical or functional food ingredient for preventing HFD-induced gut derangements and associated metabolic complications.

Prebiotic oligofructose protects against high-fat diet-induced obesity by changing the gut microbiota, intestinal mucus production, glycosylation and secretion

Obesity is a major risk factor for the development of type 2 diabetes and cardiovascular diseases, and gut microbiota plays a key role in influencing the host energy homeostasis. Moreover, obese mice have a different gut microbiota composition, associated with an alteration of the intestinal mucus layer, which represents the interface between the bacteria and the host. We previously demonstrated that prebiotic treatment with oligofructose (FOS) counteracted the effects of diet-induced obesity, together with changes in the gut microbiota composition, but it is not known if the intestinal mucus layer could be involved. In this study, we found that, in addition to preventing high-fat diet (HFD) induced obesity in mice, the treatment with FOS increased the expression of numerous genes involved in mucus production, glycosylation and secretion, the expression of both secreted and transmembrane mucins, and the differentiation and number of goblet cells. These results were associated with significant changes in the gut microbiota composition, with FOS significantly increasing the relative and absolute abundance of the bacterial genera Odoribacter, Akkermansia, two unknown Muribaculaceae and an unknown Ruminococcaceae. Interestingly, all these bacterial genera had a negative association with metabolic parameters and a positive association with markers of the mucus layer. Our study shows that FOS treatment is able to prevent HFD-induced metabolic disorders, at least in part, by acting on all the processes of the mucus production. These data suggest that targeting the mucus and the gut microbiota by using prebiotics could help to prevent or mitigate obesity and related disorders.

Oleuropein Prevents OVA-Induced Food Allergy in Mice by Enhancing the Intestinal Epithelial Barrier and Remodeling the Intestinal Flora

SCOPE

This study assesses whether oleuropein prevents ovalbumin (OVA)-induced food allergy (FA) and investigates the underlying mechanisms.

METHODS AND RESULTS

A Balb/c FA mouse model is established and maintained for 7 weeks. The subjects are administered OVA by oral gavage to induce FA and supplemented with different oleuropein doses (1.00-20.00 mg kg^-1 per day) to evaluate its preventative efficacy. The results indicate that oleuropein effectively alleviates OVA-induced allergy symptoms and promotes temperature elevation in sensitized mice. The secretion of serology-specific OVA-immunoglobulin (Ig)E, OVA-IgG, and histamine is inhibited in the sensitized mice. Oleuropein dramatically upregulates the expression of intestinal tight junction (TJ) proteins, regenerating gene (Reg) IIIγ, and interleukin (IL)-22, enhancing the physical and biochemical barrier function of the intestinal epithelium. Additionally, oleuropein improves the immune homeostasis of the intestinal epithelium by affecting the function of mucosal mast cells and regulatory T (Treg) cells. The disordered intestinal flora of the sensitized mice also improves after oleuropein administration.

CONCLUSIONS

These findings suggest that oleuropein prevents FA by enhancing intestinal epithelial barrier function and improving immune homeostasis and intestinal flora in sensitized mice. Therefore, diets rich in oleuropein should be recommended for people with FA.

Dietary Capsaicin: A Spicy Way to Improve Cardio-Metabolic Health?

Today's sedentary lifestyle with too much food and too little exercise has made metabolic syndrome a pandemic. Metabolic syndrome is a major risk factor for type-2 diabetes and cardiovascular disease. New knowledge of medical and nutraceutical intervention in the early stages of metabolic syndrome is central to prevent these deadly complications. People who eat chili pepper on a regular basis seem to stay healthier and live longer than those who do not. Animal experiments suggest a therapeutic potential for dietary capsaicin, the active principle in hot chili pepper, to reduce the risk of developing metabolic syndrome. This is an attractive theory since capsaicin has been a culinary staple for thousands of years, and is generally deemed safe when consumed in hedonically acceptable doses. The broad expression of the capsaicin receptor TRPV1 in metabolically active tissues lends experimental support to this theory. This review critically evaluates the available experimental and clinical evidence for and against dietary capsaicin being an effective dietary means to improve cardio-metabolic health. It comes to the conclusion that although a chili pepper-rich diet is associated with a reduced risk of dying due to cardiovascular disease, dietary capsaicin has no clear effect on blood glucose or lipid profiles. Therefore, the reduced mortality risk may reflect the beneficial action of digested capsaicin on gut microbiota.

Intrarectal Capsazepine Administration Modulates Colonic Mucosal Health in Mice

Antagonism of transient receptor potential vanniloid-1 (TRPV1) and desensitization of transient receptor potential ankyrin-1 (TRPA1) nociceptors alleviate inflammatory bowel diseases (IBD)-associated chronic pain. However, there is limited literature available about their role in regulating the mucosal layer, its interaction with host physiology, and luminal microbial community. The present study focuses on the effects’ intra rectal administration of capsazepine (modulator of TRPA1/TRPV1 expressing peptidergic sensory neurons) on colonic mucus production and gut health. We performed histological analysis, gut permeability alteration, gene expression changes, metabolite profiling, and gut microbial abundance in the ileum, colon, and cecum content of these animals. Intra rectal administration of capsazepine modulates TRPA1/TRPV1-positive nociceptors (behavioral pain assays) and resulted in damaged mucosal lining, increased gut permeability, and altered transcriptional profile of genes for goblet cell markers, mucus regulation, immune response, and tight junction proteins. The damage to mucosal lining prevented its role in enterosyne (short chain fatty acids) actions. These results suggest that caution must be exercised before employing TRPA1/TRPV1 modulation as a therapeutic option to alleviate pain caused due to IBD.

Capsaicin for Weight Control: “Exercise in a Pill” (or Just Another Fad)?

Medical management of obesity represents a large unmet clinical need. Animal experiments suggest a therapeutic potential for dietary capsaicin, the pungent ingredient in hot chili peppers, to lose weight. This is an attractive theory since capsaicin has been a culinary staple for thousands of years and is generally deemed safe when consumed in hedonically acceptable, restaurant-like doses. This review critically evaluates the available experimental and clinical evidence for and against capsaicin as a weight control agent and comes to the conclusion that capsaicin is not a magic “exercise in a pill”, although there is emerging evidence that it may help restore a healthy gut microbiota.