Low-methoxyl lemon pectin attenuates inflammatory responses and improves intestinal barrier integrity in caerulein-induced experimental acute pancreatitis

Effects of pectin methyl-esterification on intestinal microbiota and its immunomodulatory properties in naive mice

Pectins are dietary fibers that are attributed with several beneficial immunomodulatory effects. Depending on the degree of esterification (DE), pectins can be classified as high methoxyl pectin (HMP) or low methoxyl pectin (LMP). The aim of this study was to investigate the effects of pectin methyl-esterification on intestinal microbiota and its immunomodulatory properties in naive mice. Supplementation of the diet with LMP or HMP induced changes in the composition of the intestinal microbiota in mice toward Bacteroides, which was mainly promoted by HMP. Metabolome analysis of stool samples from pectin-fed mice showed a different effect of the two types of pectin on the levels of short-chain fatty acids and bile acids, which was consistent with highly efficient in vivo fermentation of LMP. Analysis of serum antibody levels showed a significant increase in IgG and IgA levels by both pectins, while FACS analysis revealed a decrease of infiltrating inflammatory cells in the intestinal lamina propria by HMP. Our study revealed that the structural properties of the investigated pectins determine fermentability, effects on microbial composition, metabolite production, and modulation of immune responses. Consumption of HMP preferentially altered the gut microbiota and suppressed pro-inflammatory immune responses, suggesting a beneficial role in inflammatory diseases.

Ripe papaya pectins inhibit the proliferation of colon cancer spheroids and the formation of chemically induced aberrant crypts in rats colons

Pectins are a class of soluble polysaccharides that can have anticancer properties through several mechanisms. This study aimed to characterize the molecular structure of water-soluble fractions (WSF) derived from ripe and unripe papayas and assess their biological effects in two models: the 3D colon cancer spheroids to measure cell viability and cytotoxicity, and the in vivo model to investigate the inhibition of preneoplastic lesions in rats. WSF yield was slightly higher in ripe papaya, and both samples mainly consisted of pectin. Both pectins inhibited the growth of colon cancer HT29 and HCT116 spheroids. Unripe pectin disturbed HT29/NIH3T3 spheroid formation, decreased HCT116 spheroid viability, and increased spheroid cytotoxicity. Ripe pectin had a more substantial effect on the reduction of spheroid viability for HT29 spheroids. Furthermore, in vivo experiments on a rat model revealed a decrease in aberrant crypt foci (ACF) formation for both pectins and increased apoptosis in colonocytes for ripe papaya pectins. The results suggest potential anticancer properties of papaya pectin, with ripe pectin showing a higher potency.

Modulation of pectin on intestinal barrier function via changes in microbial functional potential and bile acid metabolism

Weaning is one of the major factors that cause stress and intestinal infection in infants and in young animals due to an immature intestine and not fully developed immune functions. Pectin (PEC), a prebiotic polysaccharide, has attracted considerable attention in intestinal epithelial signaling and function via modulation of the microbial community. A total of 16 weaned piglets (21-d-old) were randomly assigned into two groups: control group and PEC group. Supplementation of 5% pectin improved intestinal mucosal barrier function by modulating the composition of the bile acid pool in piglets. Specifically, piglets in PEC group had less serum D-lactate content and alkaline phosphatase activity. In the ileum, dietary pectin increased the number of crypt PAS/AB-positive goblet cells and the mRNA expressions of MUC2, ZO-1, and Occludin. Piglets in PEC group displayed a decreased abundance of Enterococcus (2.71 vs. 65.92%), but the abundances of Lactobacillus (30.80 vs. 7.93%), Streptococcus (21.41 vs. 14.81%), and Clostridium_sensu_stricto_1 (28.34 vs. 0.01%) were increased. Elevated concentrations of bile acids especially hyocholic acid species (HCAs) including HCA, HDCA, and THDCA were also observed. Besides, correlation analysis revealed that dietary pectin supplementation may have beneficial effects through stimulation of the crosstalk between gut microbes and bile acid synthesis within the enterohepatic circulation. Thus, dietary pectin supplementation exhibited a further positive effect on the healthy growth and development of weaned piglets. These findings suggest pectin supplementation as the prebiotic is beneficial for gut health and improvement of weaned stress via regulating microbiota and bile acid metabolism.

Dietary fiber pectin: challenges and potential anti-inflammatory benefits for preterms and newborns

Pectins, a class of dietary fibers abundant in vegetables and fruits, have drawn considerable interest due to their potential anti-inflammatory properties. Numerous studies have indicated that incorporating pectins into infant formula could be a safe strategy for alleviating infant regurgitation and diarrhea. Moreover, pectins have been shown to modulate cytokine production, macrophage activity, and NF-kB expression, all contributing to their anti-inflammatory effects. Despite this promising evidence, the exact mechanisms through which pectins exert these functions and how their structural characteristics influence these processes remain largely unexplored. This knowledge is particularly significant in the context of gut inflammation in developing preterm babies, a critical aspect of necrotizing enterocolitis (NEC), and in children and adults dealing with inflammatory bowel disease (IBD). Our mini review aims to provide an up-to-date compilation of relevant research on the effects of pectin on gut immune responses, specifically focusing on preterms and newborns. By shedding light on the underlying mechanisms and implications of pectin-mediated anti-inflammatory properties, this review seeks to advance our knowledge in this area and pave the way for future research and potential therapeutic interventions.

The Interaction of Microbiome and Pancreas in Acute Pancreatitis

Acute pancreatitis (AP) is a common acute abdomen disease characterized by the pathological activation of digestive enzymes and the self-digestion of pancreatic acinar cells. Secondary infection and sepsis are independent prognosticators for AP progression and increased mortality. Accumulating anatomical and epidemiological evidence suggests that the dysbiosis of gut microbiota affects the etiology and severity of AP through intestinal barrier disruption, local or systemic inflammatory response, bacterial translocation, and the regulatory role of microbial metabolites in AP patients and animal models. Recent studies discussing the interactions between gut microbiota and the pancreas have opened new scopes for AP, and new therapeutic interventions that target the bacteria community have received substantial attention. This review concentrates on the alterations of gut microbiota and its roles in modulating gut-pancreas axis in AP. The potential therapies of targeting microbes as well as the major challenges of applying those interventions are explored. We expect to understand the roles of microbes in AP diagnosis and treatment.

The potential of dietary fiber in building immunity against gastrointestinal and respiratory disorders

The numerous health benefits of dietary fibers (DFs) justify their inclusion in human diets and biomedical products. Given the short- and long-term human impacts of the COVID-19 virus on human health, the potential of DFs in building immunity against gastrointestinal and respiratory disorders is currently receiving high attention. This paper reviews the physicochemical properties of DFs, together with their immune functions and effects on the gastrointestinal tract and respiratory system mainly based on research in the last ten years. Possible modes of action of DFs in promoting health, especially building immunity, are explored. We seek to highlight the importance of understanding the exact physical and chemical characteristics and molecular behaviors of DFs in providing specific immune function. This review provides a perspective beyond the existing recognition of DFs' positive effects on human health, and offers a theoretical framework for the development of special DFs components and their application in functional foods and other therapeutic products against gastrointestinal and respiratory disorders. DFs enhance immunity from gastrointestinal and respiratory diseases to promote host health.

Pectin from sunflower by-products obtained by ultrasound: Chemical characterization and in vivo evaluation of properties in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a public health challenge and the use of pectin for symptom amelioration is a promising option. In this work, sunflower pectin has been extracted without (CHP) and with assistance of ultrasound (USP) using sodium citrate as a food-grade extracting agent. At optimal conditions (64 °C, 23 min) the highest yield was obtained with ultrasound application (15.5 vs. 8.1 %). Both pectins were structurally characterized by 1H NMR, HPSEC-ELSD, FT-IR and GC-FID. Unlike CHP, USP showed a lower molecular weight, higher galacturonic acid, lower degree of methyl-esterification and, overall, higher viscosity. These characteristics could affect the anti-inflammatory activity of pectins, evaluated using DSS-induced IBD model mice. So, USP promoted the defence (ICAM-1) and repair of the gastrointestinal mucosa (TFF3, ZO-1) more effectively than CHP. These results demonstrate the potential amelioration of acute colitis in IBD mice through USP supplementation. Taking into account the biomarkers analysed, these results demonstrate, for the first time, the positive impact of sunflower pectin extracted by ultrasound under very soft conditions on inflammatory bowel disease that might open up new possibilities in the treatment of this serious pathology.

The effects of pectin on the gut microbiota and serum metabolites in mice fed with a high fat diet and exposed to low-dose antibiotics

A sedentary lifestyle, unhealthy diet, and antibiotic use among other environmental factors have been associated with an increased incidence of metabolic disorders and inflammation, as well as gut dysbiosis. Pectin is an edible polysaccharide that exists widely in the cell wall of plants. Our previous study has shown that pectin with various degrees of esterification displayed different effects on preventing acute colitis and regulating the gut microbiome and serum metabolome. This study aimed to further explore the differential effects of pectin with various degrees of esterification on mice simultaneously treated with a high-fat diet and low-dose antibiotics. The results showed that low-esterified pectin L102 improved the biomarkers of metabolic disorders including blood glucose and body weight. The high-esterified pectin H121 and the low-esterified pectin L13 ameliorated inflammatory markers such as superoxide dismutase (SOD). The enrichment of probiotic bacteria such as Lactobacillus by pectin L102, reduction of conditional pathogens such as Klebsiella by pectin L13, and changes in circulating metabolites like L-tryptophan and 3-indoleacrylate by all three types of pectins were detected. These data provide evidence for a differential effect of different types of pectin on the gut microbiota and metabolic health.

Longan pulp polysaccharides regulate gut microbiota and metabolites to protect intestinal epithelial barrier

Longan pulp polysaccharide is a bioactive component with prebiotic activity and intestinal barrier protection. This study aimed to evaluate the influence of digestion and fermentation on the bioavailability and intestinal barrier protection of polysaccharide LPIIa from longan pulp. The molecular weight of LPIIa didn't change significantly after gastrointestinal digestion in vitro. After fecal fermentation, 56.02% of LPIIa was consumed by gut microbiota. The short-chain fatty acid level in LPIIa group was 51.63% higher than that in blank group. LPIIa intake also increased short-chain fatty acid production and G-protein-coupled receptor 41 expression in the colon of mice. Moreover, LPIIa improved the relative richness of Lactobacillus, Pediococcus, and Bifidobacterium in colon content. Compared to LPIIa, fecal fermented LPIIa better protected intestinal epithelial barrier by increasing Zonula occludens-1 expression. These results provided an important basis for the design of functional food based on longan polysaccharides to prevent intestinal barrier damage related diseases.

A comparison of study on intestinal barrier protection of polysaccharides from Hericium erinaceus before and after fermentation

The intestinal barrier protects the host from harmful substances. This paper investigated two polysaccharides extracted from the Hericium erinaceus before and after fermentation (HEP and FHEP). The effects of two polysaccharides on the intestinal barrier were investigated in cell and mice models. The results showed that polysaccharides had a protective effect against acrylamide-induced injury in IEC-6 cell. Compared with HEP, FHEP significantly increased TEER and paracellular permeability (P < 0.05). Both polysaccharides the expression of alter tight junction (TJ) and mucin (MUC) as observed in cell Western Bolt (WB). Polysaccharides also enhance the intestinal barrier function in mice by improving cyclophosphamide induced cytokines level, TJ and MUC expression, and gut microbiota. The results showed that FHEP significantly increased IgA, IgG, and IgM levels while decreasing TNF-, IL-1, and IL-6 levels (P < 0.05). The immunohistochemical results showed that both polysaccharides significantly increased the expression of occludin, ZO-1, ZO-2, claudin-3, claudin-4, MUC2 and decreased claudin-2. In parallel, polysaccharides could alter the composition of the gut microbiota, indicating that increased in Bacteriodetes, Firmicutes and decreased in Klebsiella and Shigella. This work provides important views on the protective effect of fermented polysaccharides on the intestinal barrier, and provides a potential mechanism for the beneficial health properties of these biomacromolecules.

Serum short chain fatty acids mediate hippocampal BDNF and correlate with decreasing neuroinflammation following high pectin fiber diet in mice

Introduction

Dietary components, such as prebiotic fiber, are known to impact brain chemistry via the gut-brain axis. In particular, short chain fatty acids (SCFAs) generated from excessive soluble fiber consumption are thought to impact neuroimmune signaling and brain function through increased production of neurotropic factors. Given reports that high dietary fiber intake is associated with increased mental health and improved quality of life scores, we set out to identify whether changes in SCFA levels as a result of a high soluble fiber diet mediate hippocampal neuroinflammation and brain derived neurotrophic factor (BDNF) in mice.

Methods

Adult male and female C57BL/6 mice were fed a 1-month high pectin fiber or cellulose-based control diet. Following 1 month of excessive pectin consumption, serum SCFAs were measured using gas chromatography-mass spectrometry (GC-MS) and hippocampal cytokines and BDNF were assessed via multiplex magnetic bead immunoassay.

Results

Pectin-based fiber diet increased circulating acetic acid in both sexes, with no effect on propionic or butyric acid. In the hippocampus, a high fiber diet decreased TNFa, IL-1ß, IL-6, and IFNγ and increased BDNF levels. Furthermore, increased SCFA levels were inversely correlated with neuroinflammation in the hippocampus, with acetic acid revealed as a strong mediator of increased BDNF production.

Conclusion

Collectively, these findings highlight the beneficial effects of fiber-induced molecular changes in a brain region known to influence mood- and cognition-related behaviors. Dietary composition should be considered when developing mental health management plans for men and women with an emphasis on increasing soluble fiber intake.

Opportunities and challenges of polyphenols and polysaccharides for type 1 diabetes intervention

Type 1 diabetes (T1D) is an autoimmune disorder characterized by the destruction of insulin-producing pancreatic β cell. It contributes to high mortality, frequent diabetic complications, poor quality of life in patients and also puts a significant economic burden on health care systems. Therefore, the development of new therapeutic strategies is urgently needed. Recently, certain dietary compounds with potential applications in food industry, particularly polyphenols and polysaccharides, have gained increasing attention with their prominent anti-diabetic effects on T1D by modulating β cell function, the gut microbiota and/or the immune system. In this review, we critically discuss the recent findings of several dietary polyphenols and polysaccharides with the potential to protect against T1D and the underlying anti-diabetic mechanisms. More importantly, we highlight the current trends, major issues, and future directions of industrial production of polyphenols- and polysaccharides-based functional foods for preventing or delaying T1D.

Pectin supplementation ameliorates intestinal epithelial barrier function damage by modulating intestinal microbiota in lipopolysaccharide-challenged piglets

During weaning, infants and young animals are susceptible to severe enteric infections, thus inducing intestinal microbiota dysbiosis, intestinal inflammation, and impaired intestinal barrier function. Pectin (PEC), a prebiotic polysaccharide, enhances intestinal health with the potential for therapeutic effect on intestinal diseases. One 21-days study was conducted to investigate the protective effect of pectin against intestinal injury induced by intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS) in a piglet model. A total of 24 piglets (6.77±0.92 kg BW; Duroc × Landrace × Large White; barrows; 21 d of age) were randomly assigned into three groups: control group, LPS-challenged group, and PEC + LPS group. Piglets were administrated with LPS or saline on d14 and d21 of the experiment. All piglets were slaughtered and intestinal samples were collected after 3 h administration on d21. Pectin supplementation ameliorated the LPS-induced inflammation response and damage to the ileal morphology. Meanwhile, pectin also improved intestinal mucin barrier function, increased the mRNA expression of MUC2, and improved intestinal mucus glycosylation. LPS challenge reduced the diversity of intestinal microbiota and enriched the relative abundance of Helicobacter. Pectin restored alpha diversity improved the structure of the gut microbiota by enriching anti-inflammatory bacteria and short-chain fatty acid (SCFA)-producing bacteria, and increased the concentrations of acetate. In addition, Spearman rank correlation analysis also revealed the potential relationship between intestinal microbiota and intestinal morphology, intestinal inflammation, and intestinal glycosylation in piglets. Taken together, these results indicate that pectin enhances intestinal integrity and barrier function by altering intestinal microbiota composition and their metabolites, which subsequently alleviates intestinal injury and finally improves the growth performance of piglets.

The gut-lung axis in severe acute Pancreatitis-associated lung injury: The protection by the gut microbiota through short-chain fatty acids

The role of gut microbiota in regulating the intestinal homeostasis, as well as the pathogenesis of severe acute pancreatitis-associated lung injury (PALI) is widely recognized. The bioactive functions of metabolites with small molecule weight and the detail molecular mechanisms of PALI mediated by "gut-lung axis" have gradually raised the attentions of researchers. Several studies have proved that short-chain fatty acids (SCFAs) produced by gut microbiome play crucial roles and varied activities in the process of PALI. However, relevant reviews reporting SCFAs in the involvement of PALI is lacking. In this review, we firstly introduced the synthetic and metabolic pathways of SCFAs, as well as the transport and signal transduction routes in brief. Afterwards, we focused on the possible mechanisms and clues of SCFAs to participate in the fight against PALI which referred to the inhibition of pathogen proliferation, anti-inflammatory effects, enhancement of intestinal barrier functions, and the maintenance and regulation of immune homeostasis via pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In addition, the latest reported pathological and physiological mechanisms of the gut-lung axis involved in PALI were reviewed. Finally, we summarized the potential therapeutic interventions of PALI by targeting SCFAs, including dietary fiber supplementation, direct supplementation of SCFAs/prebiotics/probiotics, and drugs administration, which is expected to provide new sights for clinical use in the future.

Structural characterization, acute toxicity assessment and protective effects of selenylated apple pectin on dextran sulfate sodium-induced ulcerative colitis

This study was aimed at investigating the structural characterization, acute toxicity and protective effect of selenylated apple pectin on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice. Selenylated apple pectin was characterized by ion chromatography, NMR and SEC-RI-MALLS. The acute toxicity and protective effect of selenylated apple pectin against UC were investigated by gavage administration in mice. The organ state and coefficients, inflammatory cytokine (IL-6, IL-10 and TNF-α) contents in serum, GSH-Px activity and MPO content in colon tissues were also evaluated. The results indicated that selenylated apple pectin was non-toxic and contained 244.28 μg_selenium per g. The monosaccharide composition with different molar ratios, different relative molecular weights and a weakened signal peak (CH₂-O group) at 3-4 ppm were observed after selenylation. The selenylated apple pectin showed the protective effect against UC by down-regulating IL-6 and TNF-α contents and up-regulating the IL-10 content in serum, as well as increasing the GSH-Px activity and decreasing the MPO content in colon tissues. Moreover, DSS-induced alterations were effectively recovered by a high-dose sample. These findings provide evidence in support of selenylated apple pectin as a novel dietary selenium supplement for UC protection.

Structure and function of non-digestible carbohydrates in the gut microbiome

Together with proteins and fats, carbohydrates are one of the macronutrients in the human diet. Digestible carbohydrates, such as starch, starch-based products, sucrose, lactose, glucose and some sugar alcohols and unusual (and fairly rare) α-linked glucans, directly provide us with energy while other carbohydrates including high molecular weight polysaccharides, mainly from plant cell walls, provide us with dietary fibre. Carbohydrates which are efficiently digested in the small intestine are not available in appreciable quantities to act as substrates for gut bacteria. Some oligo- and polysaccharides, many of which are also dietary fibres, are resistant to digestion in the small intestines and enter the colon where they provide substrates for the complex bacterial ecosystem that resides there. This review will focus on these non-digestible carbohydrates (NDC) and examine their impact on the gut microbiota and their physiological impact. Of particular focus will be the potential of non-digestible carbohydrates to act as prebiotics, but the review will also evaluate direct effects of NDC on human cells and systems.

A water soluble extract of radish greens ameliorates high fat diet-induced obesity in mice and inhibits adipogenesis in preadipocytes

Radish (Raphanus sativus L.) is a rich source of nutrients and its greens have reported functionalities. This study aimed to investigate the effects of a water-soluble extract from radish greens (WERG) on adipogenesis in 3T3-L1 adipocytes and high-fat diet-induced obesity in model mice. We also quantified the phytochemical composition of WERG such as glucoraphenin and ferulic acid. These findings show that treatment with 100 μg mL^-1 WERG reduced lipid accumulation in 3T3-L1 adipocytes, whereas in mice, the administration of 100 mg kg^-1 WERG reduced weight gain and hepatic lipid accumulation and improved the levels of serum lipid biomarkers. Furthermore, WERG treatment improved intestinal permeability and suppressed the activities of harmful intestinal enzymes in feces, thus improving gut health. It also inhibited metabolic endotoxemia and inflammatory marker levels in serum. Moreover, WERG reduced the expression of lipid-metabolism-related proteins in the liver and white adipose tissue. Collectively, these results indicate that WERG may potentiate the anti-obesity effect by improving gut health and regulating lipid metabolism.

MiR155 Disrupts the Intestinal Barrier by Inducing Intestinal Inflammation and Altering the Intestinal Microecology in Severe Acute Pancreatitis

BACKGROUND

Intestinal dysfunction is a common complication of acute pancreatitis. MiR155 may be involved in the occurrence and development of intestinal dysfunction mediated by acute pancreatitis, but the specific mechanism is not clear.

AIMS

To investigate the effect of miR155 on severe acute pancreatitis (SAP)-associated intestinal dysfunction and its possible mechanism in a mice model.

METHODS

In this study, SAP mice model was induced by intraperitoneal injection of caerulein and LPS in combination. Adeno-associated virus (AAV) was given by tail vein injection before the SAP model. The pancreatic and intestinal histopathology changes were analyzed. Cecal tissue was collected for 16S rRNA Gene Sequencing. Intestinal barrier proteins ZO-1 and E-cad were measured by Immunohistochemistry Staining and Western Blot, respectively. Intestinal tissue miR155 and inflammatory factors TNF-α, IL-1β, and IL-6 were detected by Q-PCR. The expression levels of protein associated with TNF-α and TLR4/MYD88 pathway in the intestinal were detected.

RESULTS

In miR155 overexpression SAP group, the levels of tissue inflammatory factor were significantly increased, intestinal barrier proteins were significantly decreased, and the injury of intestinal was aggravated. Bacterial 16S rRNA sequencing was performed, showing miR155 promotes gut microbiota dysbiosis. The levels of TNF-α, TLR4, and MYD88 in the intestinal were detected, suggesting that miR155 may regulate gut microbiota and activate the TLR4/MYD88 pathway, thereby affecting the release of inflammatory mediators and regulating SAP-related intestinal injury. After application of miR155-sponge, imbalance of intestinal flora and destruction of intestinal barrier-related proteins have been alleviated. The release of inflammatory mediators decreased, and the histopathology injury of intestinal was improved obviously.

CONCLUSION

MiR155 may play an important role in SAP-associated intestinal dysfunction. MiR155 can significantly alter the intestinal microecology, aggravated intestinal inflammation through TLR4/MYD88 pathway, and disrupts the intestinal barrier in SAP mice.

The effect of sonication-synergistic natural deep eutectic solvents on extraction yield, structural and physicochemical properties of pectins extracted from mango peels

In this study, eco-friendly deep eutectic solvents (DESs) were used as extracting agents for the first time in the extraction of pectins from mango peel. Two novel green solvents including betaine-citric acid (Bet-CA) and choline chloride-malic acid (ChCl-MaA) were screened, and the extraction conditions were further optimized by full factor design experimental along with RSM. In addition, ultrasound treatment also had an influence on extraction yield, structural and physicochemical properties of extracted pectins. Two DES-extracted pectins had significantly higher yield, larger molecular weight and particles size than HCl-extracted pectin. High intensity ultrasound power enhanced the yield of low-ester pectins, but decreased the molecular weight and particles size of the pectins extracted. Monosaccharide compositions analysis showed that higher content of galacturonic acid (GalA) and larger HG region were observed in two DESs-extracted pectins. Fourier transform infrared spectra (FT-IR) of all pectins extracted were similar, with slight differences. Two DESs-extracted pectins exhibited higher DE values than HCl-extracted pectin. Thermal analysis and zeta potential results showed that HCl-extracted pectin had better stability than ChCl-MaA-extracted pectin. Additionally, HCl-extracted pectin had higher viscosity properties than two DESs-extracted pectins or commercial pectin (CP). Moreover, it was found that HCl-extracted pectin was in a colloid state, while two DESs-extracted pectins or CP were in a flow state. Ultrasound treatment significantly improved the yields of pectin/low-ester pectin. Additionally, ultrasound treatment remarkably decreased the viscosity and viscoelastic properties of the pectins extracted. The results were conducive to our understanding of the relationship between extraction conditions and physicochemical properties of the pectins extracted, which provides theoretical basis for the functional application of mango peel pectins in the food and pharmaceutical industry.

Beneficial Effect of Kidney Bean Resistant Starch on Hyperlipidemia-Induced Acute Pancreatitis and Related Intestinal Barrier Damage in Rats

Accumulating attention has been focused on resistant starch (RS) due to its blood-lipid-lowering activities. However, reports on the potential bioactivities of RS for preventing hyperlipidemia acute pancreatitis (HLAP) are limited. Therefore, in this study, an acute pancreatitis model was set up by feeding a hyperlipidemia diet to rats, and subsequently evaluating the anti-HLAP effect of RS in kidney beans. The results show that the IL-6, IL-1β, and TNF-α of serum in each RS group were decreased by 18.67-50.00%, 7.92-22.89%, and 8.06-34.04%, respectively, compared with the model group (MOD). In addition, the mRNA expression of tight junction protein ZO-1, occludin, and antibacterial peptides CRAMP and DEFB1 of rats in each RS group increased by 26.43-60.07%, 229.98-279.90%, 75.80-111.20%, and 77.86-109.07%, respectively. The height of the villi in the small intestine and the thickness of the muscle layer of rats were also increased, while the depth of the crypt decreased. The present study indicates that RS relieves intestinal inflammation, inhibits oxidative stress, and prevents related intestinal barrier damage. These results support the supplementation of RS as an effective nutritional intervention for HLAP and associated intestinal injury.

Pectin Microspheres: Synthesis Methods, Properties, and Their Multidisciplinary Applications

There is great contemporary interest in using cleaner technologies through green chemistry and utilizing biopolymers as raw material. Pectin is found on plant cell walls, and it is commonly extracted from fruit shells, mostly apples or citrus fruits. Pectin has applications in many areas of commercial relevance; for this reason, it is possible to find available information about novel methods to transform pectin and pursuing enhanced features, with the structuring of biopolymer microspheres being highly cited to enhance its activity. The structuring of polymers is a technique that has been growing in recent decades, due to its potential for diverse applications in various fields of science and technology. Several techniques are used for the synthesis of microspheres, such as ionotropic gelation, extrusion, aerosol drying, or emulsions, with the latter being the most commonly used method based on its reproducibility and simplicity. The most cited applications are in drug delivery, especially for the treatment of colon diseases and digestive-tract-related issues. In the industrial field, it is used for protecting encapsulated compounds; moreover, the environmental applications mainly include the bioremediation of toxic substances. However, there are still many possibilities for expanding the use of this biopolymer in the environmental field.

The Impact of Intestinal Microorganisms and Their Metabolites on Type 1 Diabetes Mellitus

BACKGROUND

Type 1 diabetes mellitus (T1DM) is an autoimmune disease with a complex etiology comprising numerous genetic and environmental factors; however, many of the mechanisms underlying disease development remain unclear. Nevertheless, a critical role has recently been assigned to intestinal microorganisms in T1DM disease pathogenesis. In particular, a decrease in intestinal microbial diversity, increase in intestinal permeability, and the translocation of intestinal bacteria to the pancreas have been reported in patients and animal models with T1DM. Moreover, intestinal microbial metabolites differ between healthy individuals and patients with T1DM. Specifically, short-chain fatty acid (SCFA) production, which contributes to intestinal barrier integrity and immune response regulation, is significantly reduced in patients with T1DM. Considering this correlation between intestinal microorganisms and T1DM, many studies have investigated the potential of intestinal microbiota in preventive and therapeutic strategies for T1DM.

OBJECTIVE

The aim of this review is to provide further support for the notion that intestinal microbiota contributes to the regulation of T1DM occurrence and development. In particular, this article reviews the involvement of the intestinal microbiota and the associated metabolites in T1DM pathogenesis, as well as recent studies on the involvement of the intestinal microbiota in T1DM prevention and treatment.

CONCLUSION

Intestinal microbes and their metabolites contribute to T1DM occurrence and development and may become a potential target for novel therapeutics.

Effects of pectins on colorectal cancer: targeting hallmarks as a support for future clinical trials

The intake of dietary fibers has been associated with a reduction in the risk of colorectal cancer.

Does the Food Ingredient Pectin Provide a Risk for Patients Allergic to Non-Specific Lipid-Transfer Proteins?

Pectin, a dietary fiber, is a polysaccharide that is widely used in food industry as a gelling agent. In addition, prebiotic and beneficial immunomodulatory effects of pectin have been demonstrated, leading to increased importance as food supplement. However, as cases of anaphylactic reactions after consumption of pectin-supplemented foods have been reported, the present study aims to evaluate the allergy risk of pectin. This is of particular importance since most of the pectin used in the food industry is extracted from citrus or apple pomace. Both contain several allergens such as non-specific lipid transfer proteins (nsLTPs), known to induce severe allergic reactions, which could impair the use of pectins in nsLTP allergic patients. Therefore, the present study for the first time was performed to analyze residual nsLTP content in two commercial pectins using different detection methods. Results showed the analytical sensitivity was diminished by the pectin structure. Finally, spiking of pectin with allergenic peach nsLTP Pru p 3 led to the conclusion that the potential residual allergen content in both pectins is below the threshold to induce anaphylactic reactions in nsLTP-allergic patients. This data suggests that consumption of the investigated commercial pectin products provides no risk for inducing severe reactions in nsLTP-allergic patients.

The Dietary Fiber Pectin: Health Benefits and Potential for the Treatment of Allergies by Modulation of Gut Microbiota

Purpose of Review

The incidence of allergies is increasing and has been associated with several environmental factors including westernized diets. Changes in environment and nutrition can result in dysbiosis of the skin, gut, and lung microbiota altering the production of microbial metabolites, which may in turn generate epigenetic modifications. The present review addresses studies on pectin-mediated effects on allergies, including the immune modulating mechanisms by bacterial metabolites.

Recent Findings

Recently, microbiota have gained attention as target for allergy intervention, especially with prebiotics, that are able to stimulate the growth and activity of certain microorganisms. Dietary fibers, which cannot be digested in the gastrointestinal tract, can alter the gut microbiota and lead to increased local and systemic concentrations of gut microbiota-derived short chain fatty acids (SCFAs). These can promote the generation of peripheral regulatory T cells (T_reg) by epigenetic modulation and suppress the inflammatory function of dendritic cells (DCs) by transcriptional modulation.

The dietary fiber pectin (a plant-derived polysaccharide commonly used as gelling agent and dietary supplement) can alter the ratio of Firmicutes to Bacteroidetes in gut and lung microbiota, increasing the concentrations of SCFAs in feces and sera, and reducing the development of airway inflammation by suppressing DC function.

Summary

Pectin has shown immunomodulatory effects on allergies, although the underlying mechanisms still need to be elucidated. It has been suggested that the different types of pectin may exert direct and/or indirect immunomodulatory effects through different mechanisms. However, little is known about the relation of certain pectin structures to allergies.

Single-Cell RNA Sequencing Identifies New Inflammation-Promoting Cell Subsets in Asian Patients With Chronic Periodontitis

Periodontitis is a highly prevalent chronic inflammatory disease leading to periodontal tissue breakdown and subsequent tooth loss, in which excessive host immune response accounts for most of the tissue damage and disease progression. Despite of the imperative need to develop host modulation therapy, the inflammatory responses and cell population dynamics which are finely tuned by the pathological microenvironment in periodontitis remained unclear. To investigate the local microenvironment of the inflammatory response in periodontitis, 10 periodontitis patients and 10 healthy volunteers were involved in this study. Single-cell transcriptomic profilings of gingival tissues from two patients and two healthy donors were performed. Histology, immunohistochemistry, and flow cytometry analysis were performed to further validate the identified cell subtypes and their involvement in periodontitis. Based on our single-cell resolution analysis, we identified HLA-DR-expressing endothelial cells and CXCL13+ fibroblasts which are highly associated with immune regulation. We also revealed the involvement of the proinflammatory NLRP3+ macrophages in periodontitis. We further showed the increased cell-cell communication between macrophage and T/B cells in the inflammatory periodontal tissues. Our data generated an intriguing catalog of cell types and interaction networks in the human gingiva and identified new inflammation-promoting cell subtypes involved in chronic periodontitis, which will be helpful in advancing host modulation therapy.

Attenuation of Doxorubicin-Induced Small Intestinal Mucositis by Pectins is Dependent on Pectin's Methyl-Ester Number and Distribution

SCOPE

Intestinal mucositis is a common side effect of the chemotherapeutic agent doxorubicin, which is characterized by severe Toll-like receptor (TLR) 2-mediated inflammation. The dietary fiber pectin is shown to prevent this intestinal inflammation through direct inhibition of TLR2 in a microbiota-independent manner. Recent in vitro studies show that inhibition of TLR2 is determined by the number and distribution of methyl-esters of pectins. Therefore, it is hypothesized that the degree of methyl-esterification (DM) and the degree of blockiness (DB) of pectins determine attenuating efficacy on doxorubicin-induced intestinal mucositis.

METHODS AND RESULTS

Four structurally different pectins that differed in DM and DB are tested on inhibitory effects on murine TLR2 in vitro, and on doxorubicin-induced intestinal mucositis in mice. These data demonstrate that low DM pectins or intermediate DM pectins with high DB have the strongest inhibitory impact on murine TLR2-1 and the strongest attenuating effect on TLR2-induced apoptosis and peritonitis. Intermediate DM pectin with a low DB is, however, also effective in preventing the induction of doxorubicin-induced intestinal damage.

CONCLUSION

These pectin structures with stronger TLR2-inhibiting properties may prevent the development of doxorubicin-induced intestinal damage in patients undergoing chemotherapeutic treatment with doxorubicin.

Porous SiO2 -coated ultrasmall selenium particles nanospheres attenuate cerulein-induce acute pancreatitis in mice by downregulating oxidative stress

OBJECTIVE

To investigate the potential therapeutic role of porous SiO₂ -coated ultrasmall selenium particles nanospheres (Se@SiO₂ nanospheres) pretreatment in acute pancreatitis (AP) and to investigate the related mechanism.

METHODS

C57BL/6 mice were randomized to the normal control (CON) group, the AP (induced by cerulein injection) (CAE) group, and AP pretreated with Se@SiO₂ nanocomposites at 1 and 2 mg/kg (CAE + 1 or 2 mg/kg Se@SiO₂ ) groups, respectively. Serum levels of amylase and lipase, inflammatory cytokines (interleukin [IL]-6, IL-1β and tumor necrosis factor [TNF]-α), alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), and creatinine (Cr) were measured, and histopathology was performed to examine the tissue samples of the pancreas, lungs, kidneys and liver. Immunofluorescence assay of reactive oxygen species (ROS), myeloperoxidase (MPO) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling were conducted, and levels of MPO, malondialdehyde, superoxide dismutase and glutathione were evaluated. Finally, Western blot analysis was used to evaluate protein expressions of Nrf2, HO-1, NQO1, TLR4, MyD88 and p-p65 in pancreatic tissue.

RESULTS

Se@SiO₂ nanospheres alleviated pathological damage to the pancreas, and reduced pancreatic enzymes and inflammatory cytokines. Injury to other organs such as the liver, lungs and kidneys was also alleviated, as indicated by decreased ALT, AST, BUN, and Cr levels as well as improved histopathology. Moreover, Se@SiO₂ nanospheres reduced oxidative stress, and ultimately inhibited TLR4/ MyD88/p-p65 pathway and increased the protein expressions of NQO1, Nrf2, and HO-1.

CONCLUSION

Se@SiO₂ nanospheres may alleviate AP by relieving oxidative stress and targeting the TLR4/Myd88/p-p65 and NQO1/Nrf2/HO-1 pathways.

Parabacteroides produces acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration

BACKGROUND

The endoglycosidase heparanase which degrades heparan sulfate proteoglycans, exerts a pro-inflammatory mediator in various inflammatory disorders. However, the function and underlying mechanism of heparanase in acute pancreatitis remain poorly understood. Here, we investigated the interplay between heparanase and the gut microbiota in the development of acute pancreatitis.

METHODS

Acute pancreatitis was induced in wild-type and heparanase-transgenic mice by administration of caerulein. The differences in gut microbiota were analyzed by 16S ribosomal RNA sequencing. Antibiotic cocktail experiment, fecal microbiota transplantation, and cohousing experiments were used to assess the role of gut microbiota.

RESULTS

As compared with wild-type mice, acute pancreatitis was exacerbated in heparanase-transgenic mice. Moreover, the gut microbiota differed between heparanase-transgenic and wild-type mice. Heparanase exacerbated acute pancreatitis in a gut microbiota-dependent manner. Specially, the commensal Parabacteroides contributed most to distinguish the differences between wild-type and heparanase-transgenic mice. Administration of Parabacteroides alleviated acute pancreatitis in wild-type and heparanase-transgenic mice. In addition, Parabacteroides produced acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration.

CONCLUSIONS

The gut-pancreas axis played an important role in the development of acute pancreatitis and the acetate produced by Parabacteroides may be beneficial for acute pancreatitis treatment. Video abstract.

Impact of dietary fibers in infant formulas on gut microbiota and the intestinal immune barrier

Human milk (HM) is the gold standard for the nutrition of infants. An important component of HM is human milk oligosaccharides (hMOs), which play an important role in gut microbiota colonization and gut immune barrier establishment, and thereby contribute to the maturation of the immune system in early life. Guiding these processes is important as disturbances have life-long health effects and can lead to the development of allergic diseases. Unfortunately, not all infants can be exclusively fed with HM. These infants are routinely fed with infant formulas that contain hMO analogs and other non-digestible carbohydrates (NDCs) to mimic the effects of hMOs. Currently, the hMO analogs 2'-fucosyllactose (2'-FL), galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), and pectins are added to infant formulas; however, these NDCs cannot mimic all hMO functions and therefore new NDCs and NDC mixtures need to become available for specific groups of neonates like preterm and disease-prone neonates. In this review, we discuss human data on the beneficial effects of infant formula supplements such as the specific hMO analog 2'-FL and NDCs as well as their mechanism of effects like stimulation of microbiota development, maturation of different parts of the gut immune barrier and anti-pathogenic effects. Insights into the structure-specific mechanisms by which hMOs and NDCs exert their beneficial functions might contribute to the development of new tailored NDCs and NDC mixtures. We also describe the needs for new in vitro systems that can be used for research on hMOs and NDCs. The current data suggest that "tailored infant formulas" for infants of different ages and healthy statuses are needed to ensure a healthy development of the microbiota and the gut immune system of infants.

Pectin limits epithelial barrier disruption by Citrobacter rodentium through anti-microbial effects

SCOPE

C. rodentium is the murine equivalent of Enteropathogenic Escherichia. coli (EPEC) and Enterohemorrhagic Escherichia coli (EHEC) which induce damage to the intestinal epithelial barrier that results in diarrhea and intestinal inflammation. Dietary fibre intake can be an effective approach to limit epithelial damage by these enteric pathogens. Therefore, the protective effect of dietary fibre pectin against dysfunction of epithelial barrier integrity upon C. rodentium infection was investigated.

METHODS AND RESULTS

Pectins that structurally differed in the degree and distribution of methylesters were tested on barrier protective effects on epithelial cells against C. rodentium by measuring transepithelial electrical resistance and lucifer yellow fluxes. All three pectins protected the epithelial barrier from C. rodentium induced damage in a structure-independent manner. These barrier protective effects were also independent of pectin-induced TLR2 activation. Furthermore, the pectins induced anti-adhesive effects on C. rodentium by interacting with C. rodentium and not with epithelial cells. This may be explained by antimicrobial effects of pectins on C. rodentium and not on other enteric bacteria including Lactobacillus plantarum and E. coli. A competition ELISA for binding of C. rodentium to pectin supported this finding as it showed that pectin interacts strongly with C. rodentium, whereas it interacts weakly or not with L. plantarum or E. coli.

CONCLUSION

These findings demonstrate that pectin protects the epithelial barrier from C. rodentium induced damage by inducing anti-microbial effects.

Atractylodis macrocephalae polysaccharides protect against DSS-induced intestinal injury through a novel lncRNA ITSN1-OT1

Many dietary polysaccharides have been shown to protect the intestinal barrier integrity against several noxious stimuli. Previously, we have isolated a polysaccharide RAMPtp from Atractylodis macrocephalae Koidz, and analyzed its structure. However, the effects of RAMPtp on intestinal barrier function have not been investigated. Here, we evaluated the protective effects of RAMPtp on Dextran sulfate sodium (DSS)-induced intestinal epithelial cells (IECs) injury. The findings showed that RAMPtp boosted the proliferation and survival of IECs during DSS stimulation. Furthermore, we found that RAMPtp protected the IECs from injury induced by DSS through maintaining the barrier function and inflammation response. Mechanistically, we identified a novel lncRNA ITSN1-OT1, which was induced by RAMPtp during DSS stimulation. It blocked the nuclear import of phosphorylated STAT2 to prevent the DSS induced decreased expression and structural destroy of tight junction proteins. Hence, the study clarified the protective effects and mechanism of polysaccharides RAMPtp on DSS-induced intestinal barrier dysfunction.

The impact of the level and distribution of methyl-esters of pectins on TLR2-1 dependent anti-inflammatory responses

Pectins have anti-inflammatory effects via Toll-like receptor (TLR) inhibition in a degree of methyl-esterification-(DM)-dependent manner. However, pectins also vary in distribution of methyl-esters over the galacturonic-acid (GalA) backbone (Degree of Blockiness - DB) and impact of this on anti-inflammatory capacity is unknown. Pectins mainly inhibit TLR2-1 but magnitude depends on both DM and DB. Low DM pectins (DM18/19) with both low (DB86) and high DB (DB94) strongly inhibit TLR2-1. However, pectins with intermediate DM (DM43/DM49) and high DB (DB60), but not with low DB (DB33), inhibit TLR2-1 as strongly as low DM. High DM pectins (DM84/88) with DB71 and DB91 do not inhibit TLR2-1 strongly. Pectin-binding to TLR2 was confirmed by capture-ELISA. In human macrophages, low DM and intermediate DM pectins with high DB inhibited TLR2-1 induced IL-6 secretion. Both high number and blockwise distribution of non-esterified GalA in pectins are responsible for the anti-inflammatory effects via inhibition of TLR2-1.

The effects of different dietary fiber pectin structures on the gastrointestinal immune barrier: impact via gut microbiota and direct effects on immune cells

Pectins are dietary fibers with different structural characteristics. Specific pectin structures can influence the gastrointestinal immune barrier by directly interacting with immune cells or by impacting the intestinal microbiota. The impact of pectin strongly depends on the specific structural characteristics of pectin; for example, the degree of methyl-esterification, acetylation and rhamnogalacturonan I or rhamnogalacturonan II neutral side chains. Here, we review the interactions of specific pectin structures with the gastrointestinal immune barrier. The effects of pectin include strengthening the mucus layer, enhancing epithelial integrity, and activating or inhibiting dendritic cell and macrophage responses. The direct interaction of pectins with the gastrointestinal immune barrier may be governed through pattern recognition receptors, such as Toll-like receptors 2 and 4 or Galectin-3. In addition, specific pectins can stimulate the diversity and abundance of beneficial microbial communities. Furthermore, the gastrointestinal immune barrier may be enhanced by short-chain fatty acids. Moreover, pectins can enhance the intestinal immune barrier by favoring the adhesion of commensal bacteria and inhibiting the adhesion of pathogens to epithelial cells. Current data illustrate that pectin may be a powerful dietary fiber to manage and prevent several inflammatory conditions, but additional human studies with pectin molecules with well-defined structures are urgently needed.

Fibroblast Growth Factor (FGF) Signaling Protects Against Acute Pancreatitis-Induced Damage by Modulating Inflammatory Responses

BACKGROUND Acute pancreatitis (AP) is a symptom of sudden pancreas inflammation, which causes patients severe suffering. In general, fibroblast growth factor (FGF) levels are increased and amylase and lipase activities are elevated during AP pathogenesis, but protein concentration are low. However, the mechanism through which FGF signaling regulates AP pathogenesis remains elusive. MATERIAL AND METHODS The concentrations of PGE2, TNF-alpha, sCRP, FGF1, and FGF2 in the serum samples of the AP group and healthy control group were detected by enzyme-linked immunosorbent assay. In addition, IkappaBalpha and p-IkappaBalpha levels were analyzed in the serum samples. Subsequently, the AP rat model was established, and FGF1, FGF2, anti-FGF1, and anti-FGF2 antibodies and Bay11-7082 were injected into AP rats. TNF-alpha, PAI-1 JNK, p-JNK, IkappaBalpha, and p-IkappaBalpha levels were also examined. RESULTS Results showed that levels of PGE2, TNF-alpha, sCRP, p-IkappaBalpha, FGF1, and FGF2, as well as amylase and lipase activity were increased in patients with AP compared with those in healthy people. In addition, protein concentrations were lower in patients with AP than in the healthy group. Activation of FGF signaling by injecting FGF1 or FGF2 also inhibited AP-induced inflammation response in the pancreas and increased amylase and lipase activities, as well as protein concentration. However, the injection of FGF1 and FGF2 antibodies accelerated AP-mediated inflammation responses in the serum. In addition, Bay11-7082 injection inhibited AP activation of inflammation response and amylase and lipase activities. Protein concentration were also increased in AP rats. CONCLUSIONS FGF signaling protects against AP-mediated damage by inhibition of AP-activating inflammatory responses.

Modulation of Pectin on Mucosal Innate Immune Function in Pigs Mediated by Gut Microbiota

The use of prebiotics to regulate gut microbiota is a promising strategy to improve gut health. Pectin (PEC) is a prebiotic carbohydrate that enhances the health of the gut by promoting the growth of beneficial microbes. These microbes produce metabolites that are known to improve mucosal immune responses. This study was conducted to better understand effects of PEC on the microbiome and mucosal immunity in pigs. Pigs were fed two diets, with or without 5% apple PEC, for 72 days. Effects of PEC on the microbiota, cytokine expression, short-chain fatty acids (SCFAs) concentration and barrier function were examined in the ileum and cecum of the pigs. An integrative analysis was used to determine interactions of PEC consumption with bacterial metabolites and microbiome composition and host mucosal responses. Consumption of PEC reduced expression of pro-inflammatory cytokines such as IFN-γ, IL-6, IL-8, IL-12 and IL-18, and the activation of the pro-inflammatory NF-κB signaling cascade. Expression of MUC2 and TFF and the sIgA content was upregulated in the mucosa of PEC-fed pigs. Network analysis revealed that PEC induced significant interactions between microbiome composition in the ileum and cecum on mucosal immune pathways. PEC-induced changes in bacterial genera and fermentation metabolites, such as Akkermansia, Faecalibacterium, Oscillibacter, Lawsonia and butyrate, correlated with the differentially expressed genes and cytokines in the mucosa. In summary, the results demonstrate the anti-inflammatory properties of PEC on mucosal immune status in the ileum and cecum effected through modulation of the host microbiome.

Butyrate ameliorates caerulein-induced acute pancreatitis and associated intestinal injury by tissue-specific mechanisms

BACKGROUND AND PURPOSE

Acute pancreatitis (AP) is a common acute abdominal condition, frequently associated with intestinal barrier dysfunction, which aggravates AP retroactively. Butyrate exhibits anti-inflammatory effects in a variety of inflammatory diseases. However, its potential beneficial effect on AP and the underlying mechanisms have not been investigated.

EXPERIMENTAL APPROACH

Experimental AP was induced by caerulein hyperstimulation in wild-type and GPR109A-/- mice. Sodium butyrate was administered intragastrically for 7 days prior to caerulein hyperstimulation. Anti-inflammatory mechanisms of butyrate were further investigated in peritoneal macrophages.

KEY RESULTS

Butyrate prophylaxis attenuated AP as shown by reduced serum amylase and lipase levels, pancreatic oedema, myeloperoxidase activity, and improved pancreatic morphology. Amelioration of pancreatic damage by butyrate was associated with reduced levels of TNF-α, IL-6, and CCL2 and suppressed activation of the NLRP3 inflammasome in both pancreas and colon. Further, butyrate ameliorated pancreatic inflammation by suppressing interactions between histone deacetylase 1 (HDAC1) and AP1 and STAT1 with increased histone acetylation at H3K9, H3K14, H3K18, and H3K27 loci, resulting in suppression of NLRP3 inflammasome activation and modulation of immune cell infiltration in pancreas. Additionally, butyrate mediated STAT1/AP1-NLRP3 inflammasome suppression via HDAC1 inhibition was demonstrated in peritoneal macrophage. In colon, butyrate inhibited NLRP3 inflammasome activation via GPR109A. Accordingly, the modulatory effects of butyrate on AP, AP-associated gut dysfunction, and NLRP3 inflammasome activation were diminished in GPR109A-/- mice.

CONCLUSION AND IMPLICATIONS

Our study dissected tissue-specific anti-inflammatory mechanisms of butyrate during AP, suggesting that increased colonic levels of butyrate may be a strategy to protect against AP.

Enteral virus depletion modulates experimental acute pancreatitis via toll-like receptor 9 signaling

Enteric viruses that inhabit the intestine have profound effects on innate and adaptive immunity of the gut and thus distant organs. Acute pancreatitis (AP) is a common abdominal inflammatory disease, in which gut bacteria play an indispensable part, particularly in the severe form with local and systemic complications. So far, little is known about the role of enteric viruses in the pathophysiology of AP. In this study, we evaluated the effect of enteric virus depletion by oral anti-viral cocktail (AVC) on caerulein (Cae)-hyperstimulation induced experimental AP and underlying mechanisms. We found that AVC treatment alleviated experimental AP, accompanied by suppressed innate immune cell infiltration and TLR9 expression and signaling in pancreas and intestine. Furthermore, AVC administration reduced AP-induced interleukin-6 (IL-6) production, IL-6-activated signal transducers and activators of transcription 3 (STAT3) signaling. Concordantly, expression of AP-induced STAT3-responsive chemokines, especially monocyte chemotactic protein-1 (MCP-1) and chemokine (C-X-C motif) ligand 1 (CXCL1) was reduced, thereby contributing to modulated pancreatic immune milieu. Treatment of mice with a toll-like receptor 9 (TLR9) agonist abolished the protective effect of AVC by activation of IL6/STAT3 signaling and downstream chemokine production. Conversely, treatment of mice with TLR9 antagonists, mimicking AVC, exerted protective effects against AP. Collectively, these results suggest that depletion of enteric viruses protects mice from experimental AP through inhibiting TLR9 signaling. Our study therefore implies a previously unrecognized role of enteric viruses in AP.

Longan pulp polysaccharides relieve intestinal injury in vivo and in vitro by promoting tight junction expression

The integrity of the intestinal mucosal barrier is important for the health of the host. In this study, longan pulp polysaccharides (LP) prevented the intestinal mucosal injury by increasing the expression of mucin 2, tight junction proteins zonulae occludens-1 (ZO-1), claudin-1, claudin-4, and adherens junction E-cadherin in cyclophosphamide-treated mice. To further identify the principle bioactive component of LP, four acidic polysaccharides (LPIa, LPIIa, LPIIIa, and LPIVa) were purified, and their intestinal protection activity in vitro was compared. LPIa, LPIIa, and LPIIIa displayed an ability to increase mRNA expression of ZO-1, claudin-1, occludin, and E-cadherin in differentiated Caco-2 cells, especially LPIa. LPIa has specific structure characteristics: porous surface structure, a high molecular weight (1.47 × 10⁵ Da), and two specific glycosidic linkages of α-Araf-(1→ and →5)-α-Araf-(1→. These structure characteristics might primarily contribute to greater intestinal barrier protective effect of LPIa.

Combinatory antibiotic treatment protects against experimental acute pancreatitis by suppressing gut bacterial translocation to pancreas and inhibiting NLRP3 inflammasome pathway

Gut bacterial translocation following impaired gut barrier is a critical determinant of initiating and aggravating acute pancreatitis (AP). Antibiotic combination (ABX; vancomycin, neomycin and polymyxin b) is capable of reducing gut bacteria, but its efficacy in AP prevention and the underlying mechanism have not been investigated yet. AP was induced in BALB/c mice by caerulein (CAE) hyperstimulation. We found that ABX supplementation attenuated the severity of AP as evidenced by reduced pancreatic oedema and myeloperoxidase activity. The protective effect was also confirmed by improved histological morphology of the pancreas and decreased pro-inflammatory markers (IL-1β, TNF-α, MCP-1) in pancreas. ABX administration inhibits the activation of colonic TLR4/NLRP3 inflammasome pathway. Subsequently, down-regulated NLRP3 resulted in decreased colonic pro-inflammation (IL-1β, IL-6, MCP-1) and enhanced gut physical barrier as evidenced by up-regulation of tight junction proteins including occludin, claudin-1 and ZO-1, as well as improved histological morphology of the colon. Together, combinatory ABX therapy inhibited the translocation of gut bacteria to pancreas and its amplification effects on pancreatic inflammation by inhibiting the pancreatic NLRP3 pathway, and inhibiting intestinal-pancreatic inflammatory responses. The current study provides the basis for potential clinical application of ABX in AP.

Modulation of Gut Microbiota by Low Methoxyl Pectin Attenuates Type 1 Diabetes in Non-obese Diabetic Mice

Intestinal homeostasis underpins the development of type 1 diabetes (T1D), and dietary manipulations to enhance intestinal homeostasis have been proposed to prevent T1D. The current study aimed to investigate the efficacy of supplementing a novel specific low-methoxyl pectin (LMP) dietary fiber in preventing T1D development. Female NOD mice were weaned onto control or 5% (wt/wt) LMP supplemented diets for up to 40 weeks of age, overt diabetes incidence and blood glucose were monitored. Then broad-spectrum antibiotics (ABX) treatment per os for 7 days followed by gut microbiota transfer was performed to demonstrate gut microbiota-dependent effects. Next-generation sequencing was used for analyzing the composition of microbiota in caecum. Concentration of short chain fatty acids were determined by GC-MS. The barrier reinforcing tight junction proteins zonula occludens-2 (ZO-2), claudin-1 and NOD like receptor protein 3 (NLRP3) inflammasome activation were determined by Western blot. The proportion of CD25⁺Foxp3⁺CD4⁺ regulatory T cell (Foxp3⁺ Treg) in the pancreas, pancreatic and mesenteric lymph nodes was analyzed by flow cytometry. We found that LMP supplementation ameliorated T1D development in non-obese diabetic (NOD) mice, as evidenced by decreasing diabetes incidence and fasting glucose levels in LMP fed NOD mice. Further microbiota analysis revealed that LMP supplementation prevented T1D-associated caecal dysbiosis and selectively enriched caecal bacterial species to produce more SCFAs. The LMP-mediated microbial balance further enhanced caecal barrier function and shaped gut-pancreatic immune environment, as characterized by higher expression of tight junction proteins claudin-1, ZO-2 in caecum, increased Foxp3⁺ Treg population and decreased NLRP3 inflammasome activation in both caecum and pancreas. The microbiota-dependent beneficial effect of LMP on T1D was further proven by the fact that aberration of caecal microbiota by ABX treatment worsened T1D autoimmunity and could be restored with transfer of feces of LMP-fed NOD mice. These data demonstrate that this novel LMP limits T1D development by inducing caecal homeostasis to shape pancreatic immune environment. This finding opens a realistic option for gut microbiota manipulation and prevention of T1D in humans.

The Impact of Pectin Supplementation on Intestinal Barrier Function in Healthy Young Adults and Healthy Elderly

Intestinal barrier function is suggested to decrease with aging and may be improved by pectin intake. The aim of this study was to investigate the effects of four weeks pectin supplementation on gastrointestinal barrier function in vivo and ex vivo in different age groups. In a randomized, double-blind, placebo-controlled, parallel study, 52 healthy young adults (18-40 years) and 48 healthy elderly (65-75 years) received 15 g/day pectin or placebo for four weeks. Pre- and post-intervention, in vivo gastrointestinal permeability by a multisugar test, and defense capacity in mucosal samples were assessed. Sigmoid biopsies were collected post-intervention from subgroups for Ussing chamber experiments and gene transcription of barrier-related genes. Pectin intervention did not affect in vivo gastroduodenal, small intestinal, colonic, and whole gut permeability in young adults nor in elderly (p ≥ 0.130). Salivary and fecal sIgA and serum IgA were not significantly different between pectin versus placebo in both age groups (p ≥ 0.128). In both young adults and elderly, no differences in transepithelial electrical resistance and fluorescein flux (p ≥ 0.164) and relative expression of genes analyzed (p ≥ 0.222) were found between pectin versus placebo. In conclusion, intestinal barrier function was not affected by four weeks pectin supplementation neither in healthy young adults nor in healthy elderly.

Clostridium butyricum Strains Suppress Experimental Acute Pancreatitis by Maintaining Intestinal Homeostasis

SCOPE

Acute pancreatitis (AP) is a common abdominal inflammatory disease. Disturbed gut homeostasis secondary to pancreatic inflammation aggravates the condition retroactively. The current study investigates potential beneficial effects of Clostridium butyricum (C. butyricum) strains on AP and underlying mechanisms.

METHODS AND RESULTS

C. butyricum strains MIYAIRI 588 (CBM588) and CGMCC0313.1 (CB0313.1) were supplemented to mice for three weeks before experimental AP or SAP induction. Both CBM588 and CB0313.1 protected against AP, as evidenced by reduced serum amylase and lipase levels, pancreatic edema, and myeloperoxidase activity. Amelioration of both experimental AP and SAP by CB0313.1 indicated a non-model-specific effect. Moreover, C. butyricum inhibited pancreatic neutrophil and dendritic cell infiltration, nucleotide-binding domain leucine-rich repeat-containing family, pyrin domain-containing 3 inflammasome activation, and pro-inflammatory pathways. Additionally in the gut, C. butyricum strains attenuated AP-associated intestinal inflammation and barrier dysfunction, accompanied with reduced pathogenic bacteria Escherichia coli and Enterococcus penetration into pancreas. Gut microbiome analyses further revealed that beneficial effects of C. butyricum on pancreatic-gut homeostasis were correlated with improved dysbiosis. In particular, relative abundance of Desulfovibrionaceae decreased, and Verrucomicrobiaceae Clostridiaceae and Lactobacillaceae increased.

CONCLUSIONS

For the first time, a protective effect of C. butyricum in AP by modulating intestinal homeostasis is demonstrated.