Dietary psyllium fiber increases intestinal heat shock protein 25 expression in mice

The role of dietary fibre in intestinal heat shock protein regulation

The gastrointestinal tract serves as a pivotal physical barrier that prevents the translocation of exogenous substances from the intestinal lumen into the systemic circulation. Dysfunction of intestinal barrier function has been implicated in the pathogenesis of several diseases, such as metabolic disorders. Heat shock proteins (HSPs) play a critical role in maintaining the resilience and viability of epithelial cells when exposed to stressors. Evidence suggests that dietary fibre (DF), a known inducer of HSP production, may be a promising candidate for strengthening the intestinal barrier. Understanding the regulation of intestinal HSPs and the protective effect of DF is critical to defending against environmental threats and preserving human health. To date, six DFs—pectin, chicory, psyllium, guar gum, partially hydrolysed guar gum, and xylooligosaccharide—have been reported to have promotive effects on intestinal HSP induction. DF promotes intestinal HSP induction through gut microbiota-dependent and independent mechanisms. DF is fermented by gut microbiota to produce short-chain fatty acids, specifically butyrate and propionate, to promote HSP production. Meanwhile, DF also promotes intestinal HSP induction through direct interaction with intestinal epithelial cells, independent of gut microbiota activity, although the precise mechanism is still unclear. Regulation of intestinal HSP occurs by transcriptional modulation through activation of heat shock transcription factors, primarily heat shock factor 1, or at the post-transcriptional level by modulation of the translation process. This review highlights recent advances in understanding the role of DF in improving intestinal barrier function, with particular emphasis on the regulatory mechanisms of intestinal HSPs.

Supplemental Psyllium Fiber Increases Antimicrobial Proteins via the Tuft Cell-ILC2 Circuit and Type II Immune Response in the Mouse Small Intestine

Dietary fibers regulate intestinal barrier function; however, the precise mechanisms remain unclear. This study investigated the effects of psyllium fibers on antimicrobial protein expression, focusing on the type II immunity and tuft cell-group 2 innate lymphoid cell (ILC2) circuit in the small intestine of the mouse. Supplemental psyllium fiber upregulated antimicrobial proteins, such as small proline-rich protein 2A (SPRR2A) and resistin-like beta (RELMβ), in mouse small intestine, evidently affecting cecal microbiota composition. The psyllium fibers also increased the RNA and protein expression of molecules related to ILC2 and tuft cells, such as IL-13, IL-25, DCLK1, Gfi-1b, SH2 domain-containing protein 3C, and Spi-B. In addition, ILC2 inhibitor (disulfiram) and bitter taste receptor blocker administration reduced psyllium-induced SPRR2A and RELMβ expression. Collectively, psyllium supplementation upregulates antimicrobial proteins such as SPRR2A and RELMß via the type II immune response and tuft cell-ILC2 circuit in the mouse small intestine.

Buckwheat-enriched diet alleviates bisphenol A mediated oxidative stress via modulation of sirtuin 1 and antioxidant status in experimental rats

Present study investigated effect of dietary buckwheat in alleviating bisphenol A (BPA) mediated oxidative stress, concomitant sirtuin1 levels in serum, stomach, and liver of rats. Experimental group A and B ingested standard diet, C and D consumed buckwheat (30%); group A and C drank normal water, B and C had BPA contamination (10 mg L^-1). Sirtuin1 mean B/A ratio nearing unity in all tissues reveals inertness of BPA towards sirtuin1. Dietary buckwheat improved sirtuin1 levels both in normal (mean C/A ratio of serum, 1.65; liver, 1.24; stomach, 1.78) and BPA fed state (mean D/B ratio of serum, 1.9; liver, 1.26; stomach, 1.75). Buckwheat augmented antioxidant status in BPA fed rats as seen in mean D/B ratio of serum (catalase, 2.4; glutathione reductase (GR), 1.33; Thiols, 1.2), liver (catalase, 2; GR, 2.5; Thiols, 1.36) and stomach (catalase, 1.31; GR, 1.5; Thiols, 1.33). Therefore, buckwheat counters BPA-led oxidative stress and modulates sirtuin1.

Development of functional foods using psyllium husk and wheat bran fractions: Phytic acid contents

Wheat grain is a rich source of phosphorus which is present mostly as phytic acid and is distributed mainly in the bran and germ fractions. Phytic acid has now been recognized as an important phytochemical having antioxidant properties. This study deals with the determination of total as well as phytic phosphorus contents of psyllium (PS), course (CB) and fine wheat bran (FB) enriched pan bread and Arabic flat bread. The concentration of phytic acid in CB, FB, wheat germ, wholegrain wheat flour (WGF), white wheat flour (WWF), and psyllium were found to be 8.86 mg/g, 8.52 mg/g, 6.05 mg/g, 1.74 mg/g, 0.46 mg/g and 0.02 mg/g, respectively. Most of the phosphorus existed as phytic phosphorus (74.7–90.8%) in FB, CB, germ, and WGF as compared to only 42.6% in WWF. The level of phytic phosphorus in pan bread containing 10% CB, 20% FB (both containing with 5% PS) was found to be 0.63 mg/g and 1.53 mg/g respectively, as compared to only 0.34 mg/g in WWF pan bread, and 0.90 mg/g in WGF pan bread. The phytic phosphorus content in Arabic bread made with WGF and 3% psyllium was 1.32 mg/g as compared to only 0.48 mg/g in WWF Arabic flat bread. The results obtained indicate that the level of phytic phosphorus significantly increased in bread formulations containing CB, FB, and WGF, but no change with psyllium addition was observed. Adding these wheat mill fractions, and psyllium will enable bakeries not only to produce fiber-enriched pan bread and Arabic bread but would also benefit consumers to increase their dietary fiber intakes, and health-promoting phytochemicals coming from wheat bran and germ fractions.

Bioactive factors secreted by Bifidobacterium breve B-3 enhance barrier function in human intestinal Caco-2 cells

Intestinal barrier function is closely related to intestinal health and diseases. Recent studies demonstrate that some probiotic and commensal bacteria secrete metabolites that are capable of affecting the intestinal functions. The present study examined an enhancing effect of bioactive factors secreted by Bifidobacterium breve strain B-3 on the intestinal tight junction (TJ) barrier integrity in human intestinal Caco-2 cells. Administration of conditioned medium obtained from B. breve strain B-3 (B3CM) to Caco-2 cells for 24 h increased trans-epithelial electrical resistance (TER), a TJ barrier indicator, across their monolayers. Immunoblot, immunofluorescence, and qPCR analyses demonstrated that B3CM increased an integral TJ protein, claudin-4 expression. In luciferase reporter assay, the administration of B3CM enhanced the claudin-4 promoter activity, indicating the transcriptional upregulation of claudin-4. Site-directed mutation of specificity protein 1 (Sp1) binding sites in the claudin-4 promoter sequence and suppression of Sp1 expression by siRNA technology clearly reduced the enhancing effect of B3CM on claudin-4 promoter activity. Liquid chromatography/mass spectrometry detected a significant amount of acetic acid in B3CM (28.3 mM). The administration of acetic acid to Caco-2 cells partially mimicked a B3CM-mediated increase in TER, but failed to increase claudin-4 expression. Taken together, bioactive factors secreted by B. breve B-3 enhanced the TJ barrier integrity in intestinal Caco-2 cells. Transcriptional regulation of claudin-4 through Sp1 is at least in part one of the underlying molecular mechanisms. In addition, acetic acid contributes to the B3CM-mediated barrier effect independently of claudin-4 expression.

Citrus kawachiensis Peel Powder Reduces Intestinal Barrier Defects and Inflammation in Colitic Mice

The anti-inflammatory effect of Citrus kawachiensis peel powder was examined in a murine model of dextran sodium sulfate (DSS)-induced colitic mice. In addition to the whole powder, its ethanol extract rich in polyphenolic compounds and ethanol extraction residue rich in dietary fibers were used. The whole powder ameliorated the DSS-induced body weight loss (body weight changes on day 9, Control 108 ± 2, DSS 91 ± 4, DSS+whole peel powder 106 ± 1%, p < 0.05), colon shortening (colon length, Control 5.0 ± 0.1, DSS 3.9 ± 0.1, DSS+whole peel powder 4.7 ± 0.1 cm, p < 0.05), increased expression of pro-inflammatory cytokines (e.g., TNF-α, Control 1.0 ± 0.1, DSS 22.2 ± 5.8, DSS+whole peel powder 4.3 ± 1.5 arbitrary unit, p < 0.05), and decreased expression of colonic tight junctions (TJs) (e.g., occludin, Control 1.00 ± 0.07, DSS 0.21 ± 0.07, DSS+whole peel powder 0.70 ± 0.06 arbitrary unit, p < 0.05). The resolution of abnormalities barring the decreased expression of zonula occludens-2, junctional adhesion molecule-A, and claudin-7 by the extraction residue was comparable to that achieved using the powder (body weight change 107 ± 1%; colon length 4.7 ± 0.1 cm; TNF-α 4.1 ± 0.7; occludin 0.58 ± 0.06 arbitrary unit, p < 0.05). The ethanol extract alone did not have any influence on these abnormalities (body weight change 94 ± 2%; colon length 4.1 ± 0.1 cm; TNF-α 40.5 ± 9.0 arbitrary unit; occludin 0.18 ± 0.02 arbitrary unit, p < 0.05). The powder and ethanol extraction residue, but not ethanol extract, increased fecal acetic acid concentration (Control 4.9 ± 0.6, DSS 5.0 ± 0.9, DSS+whole peel powder 8.8 ± 1.8, DSS+ethanol extract 5.3 ± 0.8, DSS+ethanol extraction residue 12.5 ± 1.1 mmol/L, p < 0.05). Taken together, DFs in the ethanol extraction residue largely contributed to the peel powder-mediated reduction of TJ barrier defect and inflammation in colitic mice.

Regulation of Antimicrobial Pathways by Endogenous Heat Shock Proteins in Gastrointestinal Disorders

Heat shock proteins (HSPs) are essential mediators of cellular homeostasis by maintaining protein functionality and stability, and activating appropriate immune cells. HSP activity is influenced by a variety of factors including diet, microbial stimuli, environment and host immunity. The overexpression and down-regulation of HSPs is associated with various disease phenotypes, including the inflammatory bowel diseases (IBD) such as Crohn’s disease (CD). While the precise etiology of CD remains unclear, many of the putative triggers also influence HSP activity. The development of different CD phenotypes therefore may be a result of the disease-modifying behavior of the environmentally-regulated HSPs. Understanding the role of bacterial and endogenous HSPs in host homeostasis and disease will help elucidate the complex interplay of factors. Furthermore, discerning the function of HSPs in CD may lead to therapeutic developments that better reflect and respond to the gut environment.

Dietary Nutrients and Bioactive Substances Modulate Heat Shock Protein (HSP) Expression: A Review

Interest in the heat shock proteins (HSPs), as a natural physiological toolkit of living organisms, has ranged from their chaperone function in nascent proteins to the remedial role following cell stress. As part of the defence system, HSPs guarantee cell tolerance against a variety of stressors, including exercise, oxidative stress, hyper and hypothermia, hyper and hypoxia and improper diets. For the past couple of decades, research on functional foods has revealed a number of substances likely to trigger cell protection through mechanisms that involve the induction of HSP expression. This review will summarize the occurrence of the most easily inducible HSPs and describe the effects of dietary proteins, peptides, amino acids, probiotics, high-fat diets and other food-derived substances reported to induce HSP response in animals and humans studies. Future research may clarify the mechanisms and explore the usefulness of this natural alternative of defense and the modulating mechanism of each substance.

Supplemental psyllium fibre regulates the intestinal barrier and inflammation in normal and colitic mice

Our previous study demonstrated that supplemental psyllium fibre increased cytoprotective heat-shock protein (Hsp) 25 levels in the intestinal cells of mice. Here, we examined the effect of psyllium fibre on colonic gene and protein expression and faecal microbiota in normal and colitic mice to improve the understanding of the preventive role of the supplement. DNA microarray analysis revealed that a 10 % psyllium fibre diet administered for 5 d up-regulated eleven extracellular matrix (ECM)-associated genes, including collagens and fibronectins, in normal mice. Acute colitis was induced using dextran sodium sulphate (DSS) in mice that were administered a pre-feeding 5 to 10 % psyllium fibre diet for 5 d. Psyllium fibre partially ameliorated or resolved the DSS-induced colon damage and inflammation characterised by body weight loss, colon shortening, increased levels of pro-inflammatory cytokines and decreased tight junction protein expression in the colon. Analysis of faecal microbiota using denaturing gradient gel electrophoresis of the PCR-amplified 16S rRNA gene demonstrated that psyllium fibre affected the colonic microbiota. Intestinal permeability was evaluated by growing intestinal Caco-2 cell monolayers on membrane filter supports coated with or without fibronectin and collagen. Cells grown on collagen and fibronectin coating showed higher transepithelial electrical resistance, indicating a strengthening of barrier integrity. Therefore, increased Hsp25 levels and modification of colonic ECM contribute to the observed psyllium-mediated protection against DSS-induced colitis. Furthermore, ECM modification appears to play a role in the strengthening of the colon barrier. In conclusion, psyllium fibre may be useful in the prevention of intestinal inflammatory diseases.