Inulin-Type Fructans Modulates Pancreatic-Gut Innate Immune Responses and Gut Barrier Integrity during Experimental Acute Pancreatitis in a Chain Length-Dependent Manner

Fructose-Containing Plant Carbohydrates: Biological Activities and Medical Applications

The review considers the chemical structure specifics and distribution in plants for fructose-containing carbohydrates (fructans). Various biological activities were observed in fructans and associated with their physicochemical features. Fructans affect many physiological and biochemical processes in the human body, improving health and reducing the risk of various disorders. Prebiotic activity is the most important physiological function of fructans. Fructans improve the microflora composition in the colon and intestinal mucosa by increasing the content of useful bacteria and decreasing the content of potentially harmful microorganisms, stimulate the physiological functions of the microflora, and provide for a better state of the intestine and a better health status. By modifying the intestinal microbiota and utilizing certain additional mechanisms, fructans can favorably affect the immune function, decrease the risk of various inflammatory processes, and to reduce the likelihood of tumorigenesis due to exposure to carcinogens. Fructans improve carbohydrate and lipid metabolism by reducing the blood levels of glucose, total cholesterol, low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL) and increasing the blood content of high-density lipoprotein (HLD). Fructans are low in calories, and their use in foods reduces the risk of obesity. Fructans facilitate higher calcium absorption and increase the bone density, thus reducing the risk of osteoporosis. Fructants protect the body from oxidative stress, intestinal infections, and parasitic invasions.

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.

Prophylactic effect of Tongxieyaofang polysaccharide on depressive behavior in adolescent male mice with chronic unpredictable stress through the microbiome-gut-brain axis

Major depression disorder is more common among adolescents and is a primary reason for suicide in adolescents. Some antidepressants are ineffective and may possess side effects. Therefore, developing an adolescent antidepressant is the need of the hour. We designed the stress model of adolescent male mice induced by chronic unpredictable stress (CUS). The mice were treated using Tongxieyaofang neutral polysaccharide (TXYF-NP), Tongxieyaofang acidic polysaccharide (TXYF-AP), TXYF-AP + TXYF-NP and fructooligosaccharide + galactooligosaccharides to determine their body weight, behavior, and serum hormone levels. RT-qPCR was used to detect the gene expression of Crhr1, Nr3c1, and Nr3c2 in the hypothalamus and hippocampus and the gene expression of glutamic acid and γ-aminobutyric acid-related receptors in the hippocampus. RT-qPCR, Western blot, and ELISA detected tryptophan metabolism in the colon, serum, and hippocampus. 16s rDNA helped sequence colon microflora, and non-targeted metabolomics enabled the collection of metabolic profiles of colon microflora. In adolescent male mice, CUS induced depression-like behavior, hypothalamic-pituitary-adrenal axis hyperactivity, hippocampal tissue damage, abnormal expression of its related receptors, and dysregulation of tryptophan metabolism. The 16s rDNA and non-targeted metabolomics revealed that CUS led to colon microflora disorder and bile acid metabolism abnormality. Tongxieyaofang polysaccharide could improve the bacterial community and bile acid metabolism disorder by upregulating the relative abundance of Lactobacillus gasseri, Lachnospiraceae bacterium 28-4, Bacteroides and Ruminococcaceae UCG-014 while preventing CUS-induced changes. TXYF-P can inhibit depression-like behavior due to CUS by regulating colonic microflora and restoring bile acid metabolism disorder. Thus, based on the different comparisons, TXYF-NP possessed the best effect.

Inulin: properties and health benefits

Inulin, a soluble dietary fiber, is widely found in more than 36 000 plant species as a reserve polysaccharide. The primary sources of inulin, include Jerusalem artichoke, chicory, onion, garlic, barley, and dahlia, among which Jerusalem artichoke tubers and chicory roots are often used as raw materials for inulin production in the food industry. It is universally acknowledged that inulin as a prebiotic has an outstanding effect on the regulation of intestinal microbiota via stimulating the growth of beneficial bacteria. In addition, inulin also exhibits excellent health benefits in regulating lipid metabolism, weight loss, lowering blood sugar, inhibiting the expression of inflammatory factors, reducing the risk of colon cancer, enhancing mineral absorption, improving constipation, and relieving depression. In this review paper, we attempt to present an exhaustive overview of the function and health benefits of inulin.

Biochanin A ameliorates caerulein-induced acute pancreatitis and associated intestinal injury in mice by inhibiting TLR4 signaling

Acute pancreatitis (AP) is an acute inflammatory abdominal disease frequently associated with intestinal barrier dysfunction. Biochanin A (BCA), a dietary isoflavone, has gained increasing interest with its pronounced biological activities. However, its potential beneficial effects on AP have not been demonstrated. Herein, we explored the protective effect of BCA on caerulein-induced AP in BALB/c mice and underlying mechanisms. BCA alleviated AP as evidenced by reduced serum amylase and lipase levels, pancreatic edema, pancreatic myeloperoxidase activity, and improved pancreatic morphology. Amelioration of pancreatic damage by BCA was associated with reduced levels of tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and monocyte chemotactic protein-1 in both pancreas and colon. Moreover, BCA attenuated AP-associated barrier damage by upregulating the expression of tight junction proteins zonulin occluding (ZO)-1, ZO-2, occludin, and claudin-1. Concomitantly, the translocation of pathogenic bacteria Escherichia coli (E. coli) to pancreas was reduced by BCA. More importantly, reduction of E. coli dissemination by BCA inhibited the TLR4-MAPK/NF-κB signaling and NLRP3 inflammasome activation, thereby protecting against AP and related intestinal injury. Consistently, TLR4 inhibition by TAK-242 pre-treatment counteracted the anti-inflammatory effects of BCA in acinar cells. Taken together, our study extends beneficial effects of BCA to AP prevention, and dietary BCA supplement may be a potential strategy to safeguard AP.

Preventing Respiratory Viral Diseases with Antimicrobial Peptide Master Regulators in the Lung Airway Habitat

The vast surface area of the respiratory system acts as an initial site of contact for microbes and foreign particles. The whole respiratory epithelium is covered with a thin layer of the airway and alveolar secretions. Respiratory secretions contain host defense peptides (HDPs), such as defensins and cathelicidins, which are the best-studied antimicrobial components expressed in the respiratory tract. HDPs have an important role in the human body's initial line of defense against pathogenic microbes. Epithelial and immunological cells produce HDPs in the surface fluids of the lungs, which act as endogenous antibiotics in the respiratory tract. The production and action of these antimicrobial peptides (AMPs) are critical in the host's defense against respiratory infections. In this study, we have described all the HDPs secreted in the respiratory tract as well as how their expression is regulated during respiratory disorders. We focused on the transcriptional expression and regulation mechanisms of respiratory tract HDPs. Understanding how HDPs are controlled throughout infections might provide an alternative to relying on the host's innate immunity to combat respiratory viral infections.

Naringenin protects against acute pancreatitis-associated intestinal injury by inhibiting NLRP3 inflammasome activation via AhR signaling

Background: In this study, we examined the functions and mechanisms by which naringenin protects against SAP (severe acute pancreatitis)-related intestinal injury by modulating the AhR/NLRP3 signaling pathway. Material and methods: Fifteen healthy male C57BL/6 mice were randomly divided into SAP (n = 12) and normal (n = 3) groups. Mice in the SAP group received caerulein and lipopolysaccharide intraperitoneal injections and were then randomly assigned to the SAP, NAR, CH223191, and Dexamethasone (DEX) groups. Pathological changes in the pancreatic and intestinal mucosa were observed by Hematoxylin & Eosin (H&E) staining. In vitro, RAW264.7 cells were exposed to lipopolysaccharide and treated with naringenin. The levels of NLRP3, AhR, IL-1β, TNF, and IL-6 in the SAP model and RAW264.7 cells were evaluated by enzyme-linked immunosorbent assay (ELISA), quantitative real-time PCR (qRT-PCR), western blot, and immunohistochemistry. The nuclear translocation of AhR was shown by immunofluorescence. AutoDockTools was used to predict the conformations of naringenin-AhR binding, and PyMol 2.4 was used to visualize the conformations. Results: Mouse pancreatic and intestinal injury was alleviated by treatment with naringenin. Naringenin inhibited the activation of the NLRP3 inflammasome and inhibited damage to intestinal tight junctions. Moreover, naringenin increased AhR nuclear translocation and activated the AhR pathway. Conclusion: Naringenin can reduce SAP-associated intestinal injury by inhibiting the activation of the NLRP3 inflammasome via the AhR signaling pathway.

Oral Lingzhi or Reishi Medicinal Mushroom Ganoderma lucidum (Agaricomycetes) Spore Powder Ameliorates Murine Colitis by Inhibiting Key Kinases Phosphorylation in MAPK Pathway

The compound ganoderma lucidum spore powder (GLSP) has emerged as an anti-inflammatory and anti-oxidative regulator. In this study, we explored the roles of GLSP against dextran sulfate sodium (DSS)-induced mouse colitis that can mimic human inflammatory bowel disease (IBD). GLSP was administered by oral gavage at a dosage of 150 mg/kg/day to the acute colitis mice induced by DSS. The DSS-induced mouse weight loss, colonic shortening, diarrhea and bloody stool were observably alleviated after GLSP treatment. The lesion of macroscopic and microscopic signs of the disease was reduced significantly and DSS-induced gut barrier dysfunction was restored via increasing the level of claudin-1, ZO1, Occu, and ZO2 with GLSP. Meanwhile, the levels of IL-6, TNF-α, IL-1β, and IL-18 in the colon were reduced in the GLSP-treated groups. In addition, phosphorylation of the MAPKs ERK1/2, p38, and AKT was suppressed after GLSP treatment. All these results demonstrated that GLSP owned a protective effect on DSS-induced colitis by inhibition of MAPK pathway, which provides a promising therapeutic approach for the treatment of colitis.

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.

Intestinal Microbiota - An Unmissable Bridge to Severe Acute Pancreatitis-Associated Acute Lung Injury

Severe acute pancreatitis (SAP), one of the most serious abdominal emergencies in general surgery, is characterized by acute and rapid onset as well as high mortality, which often leads to multiple organ failure (MOF). Acute lung injury (ALI), the earliest accompanied organ dysfunction, is the most common cause of death in patients following the SAP onset. The exact pathogenesis of ALI during SAP, however, remains unclear. In recent years, advances in the microbiota-gut-lung axis have led to a better understanding of SAP-associated lung injury (PALI). In addition, the bidirectional communications between intestinal microbes and the lung are becoming more apparent. This paper aims to review the mechanisms of an imbalanced intestinal microbiota contributing to the development of PALI, which is mediated by the disruption of physical, chemical, and immune barriers in the intestine, promotes bacterial translocation, and results in the activation of abnormal immune responses in severe pancreatitis. The pathogen-associated molecular patterns (PAMPs) mediated immunol mechanisms in the occurrence of PALI via binding with pattern recognition receptors (PRRs) through the microbiota-gut-lung axis are focused in this study. Moreover, the potential therapeutic strategies for alleviating PALI by regulating the composition or the function of the intestinal microbiota are discussed in this review. The aim of this study is to provide new ideas and therapeutic tools for PALI patients.

Gut Dysbiosis in Pancreatic Diseases: A Causative Factor and a Novel Therapeutic Target

Pancreatic-related disorders such as pancreatitis, pancreatic cancer, and type 1 diabetes mellitus (T1DM) impose a substantial challenge to human health and wellbeing. Even though our understanding of the initiation and progression of pancreatic diseases has broadened over time, no effective therapeutics is yet available for these disorders. Mounting evidence suggests that gut dysbiosis is closely related to human health and disease, and pancreatic diseases are no exception. Now much effort is under way to explore the correlation and eventually potential causation between the gut microbiome and the course of pancreatic diseases, as well as to develop novel preventive and/or therapeutic strategies of targeted microbiome modulation by probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT) for these multifactorial disorders. Attempts to dissect the intestinal microbial landscape and its metabolic profile might enable deep insight into a holistic picture of these complex conditions. This article aims to review the subtle yet intimate nexus loop between the gut microbiome and pancreatic diseases, with a particular focus on current evidence supporting the feasibility of preventing and controlling pancreatic diseases via microbiome-based therapeutics and therapies.

Dietary fibers with different viscosity regulate lipid metabolism via ampk pathway: roles of gut microbiota and short-chain fatty acid

Dietary fiber (DF) improves gastrointestinal health and has important associations with the alleviation of intestinal diseases and metabolic syndrome. However, due to DFs complex characteristics, such as solubility, viscosity, and fermentability, the mechanism in these was not consistent. As an herbivore, the goose has a prominent digestive ability to DF.

Therefore, we choose low, medium, and high viscosity DFs (respectively resistant starch-3 []RS], inulin [INU], and β–glucan [GLU]) as Magang goose diet treatment for 4 wk, to investigate the effect and potential mechanism of different viscosities DFs on the growth and development process of goose.

In summary, three degrees of viscous DFs could decrease the mechanismic lipid level of geese by promoting acid-producing bacteria and short-chain fatty acid (SCFA) production, therefore, activating AMPK pathway-related genes through the gut-liver axis. High viscous DF has a greater lipid-lowering effect on geese, while medium viscous DF has preferable intestinal mucosal protection.

Prebiotic inulin as a treatment of obesity related nonalcoholic fatty liver disease through gut microbiota: a critical review

The microbial-derived products, including short chain fatty acids, lipopolysaccharide and secondary bile acids, have been shown to participate in the regulation of hepatic lipid metabolism. Previous studies have demonstrated that prebiotics, such as oligosaccharide and inulin, have abilities to change the concentration of microbial-derived products through modulating the microbial community structure, thus controlling body weight and alleviating hepatic fat accumulation. However, recent evidence indicates that there are individual differences in host response upon inulin treatment due to the differences in host microbial composition before dietary intervention. Probably it is because of the multiple relationships among bacterial species (e.g., competition and mutualism), which play key roles in the degradation of inulin and the regulation of microbial structure. Thereby, analyzing the composition and function of initial gut microbiota is essential for improving the efficacy of prebiotics supplementation. Furthermore, considering that different structures of polysaccharides can be used by different microorganisms, the chemical structure of processed inulin should be tested before using prebiotic inulin to treat obesity related nonalcoholic fatty liver disease.

Chain length-dependent inulin alleviates diet-induced obesity and metabolic disorders in mice

Dietary fiber is regarded to improve host metabolic disorders through modulating gut microbiota. The study was to investigate the effects of inulin with different degree of polymerization (DP) on adiposity, related metabolic syndrome, and the possible mechanisms from the points of gut microbiota and metabolite changes. C57Bl/6J male mice were randomly allocated to normal diet (ND) group, high-fat diet (HFD) group, two HFD groups with short-chain inulin (HFD-S) and medium and long-chain inulin (HFD-ML) for 8 weeks. Compared with HFD treatment, ML-inulin supplementation significantly decreased weight gain, hepatic steatosis, chronic inflammation, and increased insulin sensitivity, energy expenditure and thermogenesis. This could be mimicked by S-inulin supplementation to some degree although it is not as effective as ML inulin. Also, mice treated with S and ML inulin had a remarkable alternation in the composition of gut microbiota and increased the production of short-chain fatty acids (SCFAs). However, reduced serum levels of essential fatty acids, vitamins B1 and B3 by HFD were further decreased by both inulin supplementations. ML inulin can prevent HFD-induced obesity and the associated metabolic disorders, and may be used as novel gut microbiota modulator to prevent HFD-induced gut dysbiosis and metabolic disorders.

N-(3',4'-dimethoxycinnamonyl) anthranilic acid alleviates severe acute pancreatitis by inhibiting intestinal barrier dysfunction and NF-κB activation

Severe acute pancreatitis (SAP) can affect intestinal barrier with a high mortality. To date, effective therapies for SAP are still in urgently need. The purpose of this study was to investigate the role of anthranilic acid active synthetic derivative, N-(3',4'-dimethoxycinnamonyl) anthranilic acid (3,4-DAA), in intestinal barrier dysfunction of SAP. In this study, SAP mice model was induced by caerulein combined with lipopolysaccharide (LPS). SAP mice were pretreated with 3,4-DAA orally. Histological structures of pancreatic and intestinal tissues were observed via hematoxylin-eosin (H&E) staining. Pancreas myeloperoxidase (MPO), serum lipase, and amylase were detected using corresponding kits. Western blot analysis and reverse transcription and quantitative PCR (RT-qPCR) were employed to determine the levels of inflammatory factors in both pancreatic and intestinal tissues. Moreover, the levels of intestinal barrier-related proteins, NLRP3 inflammasome and NF-κB pathway were examined by western blot analysis. Result revealed that 3,4-DAA significantly attenuated pancreas and intestine damage, inhibited the release of inflammatory factors and intestinal barrier dysfunction. Moreover, the expression of NLRP3 and phospho-NF-κB p65 in pancreatic and intestinal tissues was notably suppressed by 3,4-DAA. To sum up, these results demonstrated that 3,4-DAA could ameliorate SAP, partly attributing to the inhibition of intestinal barrier dysfunction and the release of inflammatory factors. These findings may provide a new mechanism support for 3,4-DAA application in the clinical treatment of SAP.

The interplay between the gut microbiota and NLRP3 activation affects the severity of acute pancreatitis in mice

Early dysbiosis of the gut microbiota is associated with the severity of acute pancreatitis (AP), although the underlying mechanism is unclear. Here, we investigated the role of crosstalk between NLRP3 and the gut microbiota in the development of AP utilizing gut microbiota deficient mice, as well as NLRP3 knockout (KO) mouse models. Pancreatic damage and systemic inflammation were improved in antibiotic-treated (Abx) and germ-free (GF) mice, accompanied by weakened activity of the intestinal NLRP3 inflammasome. Interestingly, fecal microbiota transplantation (FMT) reactivated the intestinal NLRP3 inflammasome and exacerbated the disease in Abx and GF mice. Although the gut barrier in GF and Abx mice was disrupted, gut microbiota deficiency ameliorated the severity of AP, probably due to the reduction in bacterial translocation from the gut to the pancreas. The composition of the gut microbiota was significantly different between NLRP3 KO mice and wild-type (WT) mice at baseline, and there were alterations in response to the induction of AP. While a dramatic shift in the gut microbiota with overgrowth of Escherichia-Shigella was observed in WT mice suffering from AP, there was no significant change in NLRP3 KO mice with or without AP, suggesting that NLRP3 deficiency counteracts AP-induced microbial disturbance. With a strengthened gut barrier and decreased systemic inflammation, NLRP3 KO mice showed less severe AP, as revealed by reduced pancreatic neutrophilic infiltration and necrosis. Taken together, these results identified the bidirectional modulation between the gut microbiota and NLRP3 in the progression of AP, which suggests the interplay of the host and microbiome during AP.

Biochemical Evaluation of the Antioxidant Effects of Hydroxytyrosol on Pancreatitis-Associated Gut Injury

Acute pancreatitis is a severe abdominal pathology often associated with several complications including gut dysfunction. Oxidative stress is one of the most important pathways involved in this pathology. Hydroxytyrosol (HT), a phenolic compound obtained from olive oil, has shown anti-inflammatory and antioxidant properties. We evaluated the effects of HT administration on pancreatic and intestinal injury induced by caerulein administration. CD1 female mice were administered caerulein (50 μg/kg) for 10 h. HT treatment (5 mg/kg) was performed 30 min after the first caerulein injection and for two consecutive hours afterwards. One hour after the last caerulein injection, mice were sacrificed and serum, colon and pancreatic tissue samples were collected. HT was able to reduce the serum hallmarks of pancreatitis (amylase and lipase), histological damage score in both pancreas and colon tissue, inflammatory cells recruitment (mast cells) in both injured tissues, intrapancreatic trypsin activity and overexpression of the adhesion molecules (Intercellular Adhesion Molecule-1 (ICAM-1) and P-selectin) in colon. Additionally, HT reduced cytokine (interleukin 1 beta (IL- 1β), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α)) levels in serum, pancreas and colon tissue and chemokine release (monocyte chemotactic protein-1 (MCP1/CCL2)) in pancreas and colon tissue. HT decreased lipid peroxidation and oxidative stress (superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) activity) by enhancing the nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) in both injured tissues. Moreover, HT preserved intestinal barrier integrity, as shown by the diamine oxidase (DAO) serum levels and tight junction (zonula occludens (ZO) and occludin) expression in pancreas and colon. Our findings demonstrated that HT would be an important therapeutic tool against pancreatitis-induced injuries in the pancreas and gut.

Study of the alleviation effects of a combination of Lactobacillus rhamnosus and inulin on mice with colitis

Ulcerative colitis (UC) is a common inflammatory bowel disease (IBD) that has serious harmful effects on human health. Lactobacillus rhamnosus, a probiotic, has a strong colonization and adhesion effect and improves the intestinal health of the host. Inulin has good anti-inflammatory effects and can promote the proliferation of beneficial intestinal bacteria. The purpose of this study was to investigate the alleviating effects of L. rhamnosus 1.0320 in combination with inulin on UC, examining the resulting changes in intestinal flora. A UC model was established by having mice freely drink a 3% (w/v) dextran sodium sulphate (DSS) solution for seven days. After successful modeling, the mice were given antibiotics, L. rhamnosus 1.0320 by itself, inulin by itself, and L. rhamnosus 1.0320 combined with inulin as an intragastric intervention for 28 days. The abundance and structural changes of bacteria in the intestinal content of mice were analyzed by 16S rDNA high-throughput sequencing. The study found that male BALB/c mice can successfully establish a typical model of small intestinal inflammation by freely drinking a 3% DSS solution for one week. L. rhamnosus 1.0320 combined with inulin can alleviate DSS-induced colitis, reduce the Disease Activity Index (DAI) score of the pathological damage of colon tissue, decrease myeloperoxidase (MPO) activity, increase hemoglobin content, and regulate the expression levels of inflammatory cytokines IL-1β, IL-6, TNF-α and IL-10. The intestinal flora of mice is reduced after enteritis, and its structure gets disordered. The combination of L. rhamnosus 1.0320 and inulin can increase the abundance and diversity of intestinal flora, and increase the content of beneficial bacteria. Prebiotics promote the colonization ability of probiotics. L. rhamnosus 1.0320 combined with inulin can change the intestinal flora to relieve ulcerative colitis, providing a new theoretical basis for the study of UC mechanism.

Inducible expression of defensins and cathelicidins by nutrients and associated regulatory mechanisms

Host defense peptides (HDPs) are crucial components of the body's first line of defense that protect organisms from infections and mediate immune responses. Defensins and cathelicidins are the two most important families of HDPs in mammals. In this review, we summarize the nutrients that are involved in inducible expression of endogenous defensins and cathelicidins. In addition, the mitogen-activated protein kinases (MAPK), nuclear factor kappa B (NF-κB) and histone deacetylase (HDAC) signaling pathways that play vital roles in the induction of defensin and cathelicidin expression are highlighted. Endogenous defensins and cathelicidins induced by nutrients may be potential alternatives to antibiotic treatments against infection and diseases. This review mainly focuses on the inducible expression and regulatory mechanisms of defensins and cathelicidins in multiple species by different nutrients and the potential applications of defensin- and cathelicidin-inducing nutrients.

Sexual Dimorphism in Immune Development and in Response to Nutritional Intervention in Neonatal Piglets

Although sex disparity in immunological function and susceptibility to various inflammatory and infectious disease is recognized in adults, far less is known about the situation in young infants during immune development. We have used an outbred piglet model to explore potential early sex disparity underlying both mucosal immune development and systemic responses to novel antigen. Despite similarities in intestinal barrier function and therefore, presumably, antigen exposure, females had less CD172⁺ (Sirp-α) antigen presenting cells and expression of MHCIIDR at 28 days old compared to males, along with greater regulatory T-cell numbers. This suggests that, during infancy, females may have greater potential for local immune regulation than their male counterparts. However, females also presented with significantly greater systemic antibody responses to injected ovalbumin and dietary soya. Females also synthesized significantly more IgA in mesenteric lymph nodes, whereas males synthesized more in caecal mucosa, suggesting that plasma cells were retained within the MLN in females, but increased numbers of plasma cells circulated through to the mucosal tissue in males. Significant effects of inulin and Bifidobacterium lactis NCC2818 on the developing immune system were also sex-dependent. Our results may start to explain inconsistencies in outcomes of trials of functional foods in infants, as distinction between males and females is seldom made. Since later functionality of the immune system is highly dependent on appropriate development during infancy, stratifying nutritional interventions by sex may present a novel means of optimizing treatments and preventative strategies to reduce the risk of the development of immunological disorders in later life.

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.

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 effects of inulin on the mucosal morphology and immune status of specific pathogen-free chickens

This study investigated the effects of inulin on mucosal morphology and immune function of specific pathogen-free (SPF) chickens. A total of 200 one-day-old White Leghorns SPF chickens were divided into 5 groups of 4 replicates of 10 chickens each. All SPF chickens were fed a basal diet supplemented with 0, 0.25, 0.5, 1.0, or 2.0% inulin. The mucosal morphology and immune indexes were analyzed on days 7, 14, and 21, respectively. Our results showed that the concentrations of acetate and propionate in the cecum and serum had increased with dietary inulin supplementation on day 21 (P < 0.05). Butyrate could not be detected in the cecal digesta, but was increased in the serum of 1 and 2% groups, as compared with the control group (P < 0.05). The villi height was increased (P < 0.05) and the crypt depth was decreased (P < 0.05) in the duodenum and ileum of SPF chickens fed inulin, as compared with the control group. Also, inulin at a low concentration (0.25 or 0.5%) significantly decreased (P < 0.05) the gene expression of nuclear factor-κB (NF-κB), lipopolysaccharide-induced tumor necrosis factor (LITAF) at 7, 14, and 21 d, and of interleukin-6 (IL-6), and inducible nitric oxide synthase (iNOS) at 7 and 14 d, and increased that of mucin 2 (MUC2) and claudin-1 in the ileum of SPF chickens at 7, 14, and 21 d. High inulin supplementation (2%) significantly increased the gene expression of NF-κB, LITAF, IL-6, iNOS, and Claudin-1 at 14 and 21 d compared to low inulin concentration (0.25 or 0.5%). The results indicated that the effects of inulin on mucosal immune function occurred in a dose-dependent manner. A low concentration (0.25 or 0.5%) of inulin may be beneficial in promoting intestinal immune function.

A Novel Derivative of the Natural Product Danshensu Suppresses Inflammatory Responses to Alleviate Caerulein-Induced Acute Pancreatitis

Acute pancreatitis (AP), a common abdominal inflammatory disorder, is characterized by premature intracellular activation of digestive proteases within pancreatic acini and a consecutive systemic inflammatory response. Although the mechanism remains to be fully understood, inflammation is the main cause of pancreatic damage in AP. A novel compound [4-(2-acetoxy-3-((R)-3-(benzylthio)-1-methoxy-1-oxopropan-2-ylamino)-3-oxopropyl)-1,2-phenylene diacetate (DSC)], derived from danshensu, exhibits anti-inflammatory and anti-apoptotic properties in vitro. However, its potential beneficial effect in AP has not been demonstrated. This study aimed to investigate the effects and underlying mechanisms of DSC in experimental AP in mice. We found that DSC suppressed inflammatory responses in AP by inhibiting the activation of nuclear factor-κB (NF-κB), signal transducer and activator of transcription 3 (STAT3) and nucleotide-binding domain leucine-rich repeat containing family, pyrin domain-containing 3 (NLRP3) inflammasome. Furthermore, treatment with DSC modulated the infiltration of neutrophils and the phenotypes of macrophages in mice induced with AP. Interestingly, we found that the expression of nuclear factor-erythroid 2 related factor 2 (Nrf2) and its regulated antioxidant enzyme heme oxygenase-1 (HO-1), which modulate inflammatory activities, was significantly increased in DSC-treated groups. Together, our findings demonstrate that DSC alleviates pancreatic inflammation and damage in AP by inhibiting the activation of NF-κB, STAT3, and NLRP3 inflammasome and modulating immune cell responses.

NRF2 mitigates acute alcohol-induced hepatic and pancreatic injury in mice

Binge alcohol drinking is an important health concern and well-known risk factor for the development of numerous disorders. Oxidative stress plays a critical role in the pathogenesis of acute alcoholism. Nuclear factor erythroid 2 like 2 (NRF2) is a master regulator of cellular adaptive response to oxidative insults. However, the role of NRF2 in acute alcoholism and associated pathologies remains unclear. We found that Nrf2-knockout (Nrf2-KO) mice had exaggerated hypoglycemia and hypothermia and increased mortality compared to wildtype mice after binge ethanol exposure. This phenotype was partially rescued by providing warm environment and/or glucose administration. Acute high dose of alcohol exposure resulted in substantially worsened liver and pancreatic injuries in Nrf2-KO mice. Importantly, deficiency of Nrf2 allowed severe pancreatitis and pancreatic β-cell injury with increased insulin secretion and/or leaking during binge ethanol exposure, which contributed to hypoglycemia. In contrast, a clinically used NRF2 activator dimethyl fumarate (DMF) protected against hypoglycemia and lethality induced by acute ethanol exposure. Furthermore, Nrf2-KO mice likely had defective hepatic acetaldehyde metabolism. Taken together, NRF2 plays an important protective role against acute binge alcohol-induced hepatic and pancreatic damage, which may be partially attributable to its primary regulating role in antioxidant response and impact on ethanol metabolism.

Isoliquiritigenin Protects Against Pancreatic Injury and Intestinal Dysfunction After Severe Acute Pancreatitis via Nrf2 Signaling

Severe acute pancreatitis (SAP) is a digestive system disease that is associated with a range of complications including intestinal dysfunction. In this study, we determined that the chalcone compound, isoliquiritigenin (ISL), reduces pancreatic and intestinal injury in a mouse model of SAP. These effects were achieved by suppressing oxidative stress and the inflammatory responses to SAP. This was evidenced by a reduction in histological score, and malondialdehyde (MDA), interleukin (IL)-6, tumor necrosis factor (TNF)-α and cleaved-caspase-3 (c-caspase-3) protein along with an increase in Nrf2, hemeoxygenase-1 (HO-1), quinone oxidoreductase 1 (NQO1), and superoxide dismutase (SOD). We then used Nrf2^-/- mice to test the protective effect of Nrf2 during ISL treatment of SAP. Our results indicated that Nrf2^-/- mice had greater pancreatic injury and intestinal dysfunction than wild-type mice. They also had reduced adherens junctions (P120-catenin) and tight junctions (occludin), and increased activated nuclear factor-κB (NF-κB) protein. In Nrf2^-/- mice, ISL was less effective at these functions than in the WT mice. In conclusion, this study demonstrated that ISL exerts its protective effects against oxidative stress and inflammatory injury after SAP via regulation of the Nrf2/NF-κB pathway. It also showed that the efficacy of ISL in repairing the intestinal barrier damage caused by SAP is closely related to the Nrf2 protein. Our findings demonstrated that Nrf2 is an important protective factor against SAP-induced injuries in the pancreas and intestines.

Synbiotic Effects of the Dietary Fiber Long-Chain Inulin and Probiotic Lactobacillus acidophilus W37 Can be Caused by Direct, Synergistic Stimulation of Immune Toll-Like Receptors and Dendritic Cells

SCOPE

Synbiotic effects of dietary fibers and lactobacilli are usually explained by synergistic modulation of gut microbiota. New insight, however, has demonstrated that both dietary fibers and lactobacilli can directly stimulate immune cells and benefit consumer immunity. Here, the synergistic effects of immune active long-chain inulin (lcITF) and Lactobacillus acidophilus W37 (LaW37) on dendritic cells (DCs) are investigated.

METHODS AND RESULTS

Effects of lcITF and LaW37 alone or combined were studied on Toll-like receptor (TLRs) signaling and cytokine secretion by DCs in the presence and absence of media of intestinal epithelial cell (IEC) exposed to the ingredients. Also, the effects of DC responses against Salmonella Typhimurium (STM) were investigated. Synergistic effects were observed on TLR2 and 3. Synergistic effects were not always pro-inflammatory. LaW37 was strongly pro-inflammatory, while cytokine responses were regulatory when combined with lcITF. Exposure of DCs to IECs medium changed the DCs' response, which revealed synergistic enhancing effects of lcITF/LaW37 on production of IL-6 and IL-8. DCs' response in the presence of STM and LaW37 were so strong that lcITF had no additional effect.

CONCLUSION

It is demonstrated that synbiotic effects of dietary fibers and bacteria are not limited to the effects on gut microbiota but can also occur by synergistically directly stimulating IECs and/or immune cells.

Lactobacillus acidophilus Attenuates Salmonella-Induced Stress of Epithelial Cells by Modulating Tight-Junction Genes and Cytokine Responses

Scope: Salmonellosis is a prevalent food-borne illness that causes diarrhea in over 130 million humans yearly and can lead to death. There is an urgent need to find alternatives to antibiotics as many salmonellae are now multidrug resistant. As such, specific beneficial bacteria and dietary fibers can be an alternative as they may prevent Salmonella Typhimurium (STM) infection and spreading by strengthening intestinal barrier function. Methods and Results: We tested whether immune active long-chain inulin-type fructans and/or L. acidophilus W37, L. brevis W63, and L. casei W56 can strengthen barrier integrity of intestinal Caco-2 cells in the presence and absence of a STM. Effects of the ingredients on intestinal barrier function were first evaluated by quantifying trans-epithelial electric resistance (TEER) and regulation of gene expression by microarray. Only L. acidophilus had effects on TEER and modulated a group of 26 genes related to tight-junctions. Inulin-type fructans, L. brevis W63 and L. casei W56 regulated other genes, unrelated to tight-junctions. L. acidophilus also had unique effects on a group of six genes regulating epithelial phenotype toward follicle-associated epithelium. L. acidophilus W37 was therefore selected for a challenge with STM and prevented STM-induced barrier disruption and decreased secretion of IL-8. Conclusion:L. acidophilus W37 increases TEER and can protect against STM induced disruption of gut epithelial cells integrity in vitro. Our results suggest that selection of specific bacterial strains for enforcing barrier function may be a promising strategy to reduce or prevent STM infections.

Emodin Alleviates Sodium Taurocholate-Induced Pancreatic Acinar Cell Injury via MicroRNA-30a-5p-Mediated Inhibition of High-Temperature Requirement A/Transforming Growth Factor Beta 1 Inflammatory Signaling

Pancreatitis is an inflammatory disease that is responsible for substantial morbidity and mortality, and it can induce pancreatic necrosis that starts within pancreatic acinar cells in severe cases. Emodin, a pleiotropic natural product isolated from the Chinese herb Rheum palmatum L., has effective anti-inflammatory activities. In this paper, we investigated the protective effects and molecular mechanism of emodin against sodium taurocholate (STC)-induced pancreatic acinar cells injury in vitro and in vivo; and the results showed that emodin could significantly alleviate STC-induced pancreatic acinar cells injury through decreasing trypsin, amylase and the release of inflammatory factors (tumor necrosis factor alpha, interleukin-1β, and interleukin-6). Also, we found that emodin could significantly downregulate the HTRA1, interleukin-33, myeloid differentiation primary response gene 88, TNF receptor-associated factor-6, and nuclear factor kappa-B protein levels, but upregulate the transforming growth factor beta 1 (TGF-β1) protein level. These results indicated that emodin alleviated pancreatic acinar cells injury mainly through inhibiting HTRA1/TGF-β1 signaling pathway, and this finding was further proved by the HTRA1 overexpression experiments. In addition, the inflammatory regulator microRNA-30a-5p (miR-30a-5p) was confirmed to be a transcriptional brake that controls the HTRA1 gene through using a dual luciferase reporter assay, and it was upregulated by emodin in pancreatic acinar cells. Furthermore, the pancreatic protective effects and anti-inflammatory activities of emodin were all abrogated with both miR-30a-5p inhibitor in vitro and miR-30a-5p antagomir in vivo. Collectively, these results demonstrate that miR-30a-5p/HTRA1 are the target of emodin-mediated attenuation of pancreatic acinar cell injury in pancreatitis, thus providing the foundation for further development of this natural product for medical therapy.