Intestinal barrier in inflammatory bowel disease

Role of TRPV4 in the Diagnosis and Treatment of Helicobacter pylori Infection in Children with Duodenal Ulcers

Duodenal ulcer seriously affects the quality of life and life safety of children, but the pathogenesis of children with duodenal ulcer is still unclear. As an important second messenger in the body, Ca2+ participates in the physiological and pathological processes of various diseases. Therefore, transient receptor potential vanilloid type 4 (TRPV4) as one of the channels that mediate Ca2+ has attracted widespread attention in recent years. Here, we found that TRPV4 is highly expressed in children with duodenal ulcer and has good diagnostic value through specimens of children with duodenal ulcer, and animal experiments have proved that TRPV4 is also highly expressed in duodenal ulcer mice. In addition, TRPV4 can enhance intestinal permeability, thereby promoting further infiltration of inflammatory factors. In summary, these results indicate that TRPV4 is involved in the occurrence and development of duodenal ulcer. Therefore, this study provides the diagnostic and therapeutic value of TRPV4 in children with duodenal ulcer.

Hyaluronic Acid-Melatonin Nanoparticles Improve the Dysregulated Intestinal Barrier, Microbiome and Immune Response in Mice with Dextran Sodium Sulfate-Induced Colitis

Although the cause of inflammatory bowel disease (IBD) is unclear, current studies have found that the main factors involved in its pathogenesis include imbalance of mucosal immune response, intestinal dysbiosis, and destruction of the intestinal barrier. We synthesized an amphiphilic conjugate of hyaluronic acid (HA) and melatonin (MT), which have established immunomodulatory and antioxidant properties, by stimulating their nano-aggregation. Inducing colitis by dextran sodium sulfate (DSS), HA-MT accumulated in the inflamed colon epithelium of colitis mice, and markedly improved the colitis symptoms, repaired the damaged intestinal barrier and inhibited colon inflammation. In addition, through bacterial 16S rDNA sequencing, it was found that HA-MT can restore the ratio of Firmicutes/Bacteroidetes by increasing the overall microbial richness and diversity, and alleviate the intestinal dysbiosis of mice with colitis. In the analysis of the intestinal flora at the species level, the abundance of Lactobacillus increased in colitis mice treated with HA-MT while that of Bacteroides, Blautia and Streptococcus decreased in the colitis mice treated with HA-MT. Our findings suggest that the HA-MT system is a promising prebiotic, which can relieve the symptoms of IBD by regulating the intestinal microflora and restoring intestinal homeostasis, inhibiting inflammation.

Mucosal Integrity Testing Can Detect Differences in the Rectums of Patients with Inflammatory Bowel Disease Compared to Controls: A Pilot Study

BACKGROUND

While the pathogenesis of inflammatory bowel disease (IBD) is incompletely understood, disruption of epithelial integrity is suspected to play a prominent role in disease initiation and progression. Currently, there is no convenient way to measure this in vivo.

AIMS

Our aim is to determine whether a mucosal integrity (MI) testing device that has been used to measure MI in the esophagus can also be used to measure barrier function in the colon during colonoscopy.

METHODS

Mucosal integrity testing was measured in patients with IBD (n = 17) and controls (n = 7) during colonoscopy. During the procedure, an MI catheter was passed down the working channel of the colonoscope and placed along the mucosal wall to measure MI in the rectum, left, transverse, and right colon. In patients with IBD, MI measurements and biopsies were taken in areas which appeared inflamed when present. We then determined if there was a significant difference in MI between patients with IBD and controls.

RESULTS

MI was significantly higher in the rectum of patients with IBD (CD and UC combined) versus control colons [767 (618-991) vs. 531 (418-604) ohms, P < 0.01]. There were no significant differences in MI among patients with IBD versus controls in the right, transverse, or left colon. Within the IBD group, there were no significant differences in MI between inflamed versus non-inflamed rectums. There was no correlation between quality of life scores or endoscopic severity with MI, though this study was likely underpowered to detect these differences.

CONCLUSION

Rectal MI is significantly higher in patients with IBD versus controls. Future studies are needed to determine how this information can be used clinically.

Gut Microbiota Dysbiosis and COVID-19: Possible Links

Microbiota in the gastrointestinal system is a major determinant in health and disease status with its influence on immunity. Bidirectional relationship between gut microbiota and host immune system is well balanced in healthy individuals and a disruption (dysbiosis) can lead to gastrointestinal inflammations and metabolic disorders. Growing evidence support the cross-talk between gastrointestinal microbiota and lung that maintains host homeostasis and reduces the risk of disease development. The Gut-lung axis is possibly involved in the severity of COVID-19 with the association of dysbiosis. Targeted alterations in the gut microbiota could be considered to alleviate the disease severity.

Voluntary suppression of neck reflexes during passive head-on-trunk rotations - reflex gain control vs. proprioceptive feedback

Normal subjects can completely eliminate resistance upon imposed head-on-trunk rotations when they are asked to relax. It is not, however, clear how neck reflexes to stretch can be voluntarily suppressed. Reflexive responses might be modified by adjusting the gain of the reflex loop through descending control. Theoretically, necessary corrections upon interfering disturbances during coordinated motor performance requiring the interplay of relaxation/activation may be missing if muscle relaxation is taking place exclusively by this mechanism. It has been alternatively proposed that sensory information from the periphery may be allowed to “neutralize” neck reflexes if it is fed back with opposite sign to the structures driving the reflexes. Six healthy subjects were asked to relax while subjected to head-on-trunk rotations generated by a head motor. After any initial resistance had completely subsided, the head was unexpectedly exposed to “ramp-and-hold” perturbations of up to 2° amplitude and 0.7 s duration. Resistance to stretch consistently reappeared thereupon, suggesting that stretch reflex gain had not been set to zero during the previously achieved complete relaxation. Resistance to perturbations under these circumstances was compared with the forces generated when the same ramp-and-hold displacements were delivered unpredictably to the head held stationary. A quantitative model of neck proprioceptive reflexes suppression has been thus constructed. Gain scheduling or “motor set” cannot sufficiently account for the voluntary reflex suppression during slow passive head rotations. Instead, we propose as underlying mechanism, the “neutralization” of the controlling servo by means of continuous feedback tracking displacement and force signals from the periphery.

NEW & NOTEWORTHY Head stabilizing neck reflexes can be voluntarily suppressed or activated depending on the task at hand. By applying brief perturbations unexpectedly, both during passive head-on-trunk movements and at rest, we investigated the mechanism of voluntary suppression of resistance to stretch. A physiologically plausible, neuromechanical model of voluntary/reflexive interactions was constructed favoring feedback over reflex gain adjustments. Accordingly, muscle relaxation during imposed head movements is based on sensory feedback similarly to muscle contractions during purposeful movements.

Lactobacillus casei ATCC 393 and it's metabolites alleviate dextran sulphate sodium-induced ulcerative colitis in mice through the NLRP3-(Caspase-1)/IL-1β pathway

Inflammatory bowel disease (IBD) represents a broad group of intestinal disorders, including ulcerative colitis (UC) and Crohn's disease (CD). Probiotics are increasingly being recognized as a means of treatment for people suffering from IBD. Our previous studies demonstrated that Lactobacillus casei ATCC 393 (L. casei ATCC 393) effectively alleviated enterotoxigenic Escherichia coli K88-induced intestinal barrier dysfunction. This study was conducted to investigate the protective effects of L. casei ATCC 393 and its metabolites on dextran sulfate sodium (DSS)-induced UC in C57BL/6 mice and the potential mechanism of these effects. The results showed that oral administration of L. casei ATCC 393 and its metabolites both effectively reversed the DSS-induced weight loss, and the reduction in the disease activity index (DAI), colon length, and villus height of colon tissue in mice. Compared to the DSS-induced model group, L. casei ATCC 393 and its metabolites significantly inhibited the infiltration of immune cells into the intestinal mucosa, decreased the production of pro-inflammatory factors, and increased the expression of anti-inflammatory factors in the serum and colon tissue, increased the expression levels of occludin, ZO-1, and claudin-1, and reduced the expression of nucleotide binding oligomeric domain-like receptor protein 3 (NLRP3), cysteine proteinase-1 (Caspase-1), IL-1β, and IL-18. In addition, L. casei ATCC 393 and its metabolites effectively improved DSS-induced gut microbiota dysbiosis. These results suggested that L. casei ATCC 393 and its metabolites alleviated the DSS-induced ulcerative inflammatory response in C57BL/6 mice through the NLRP3-(Caspase-1)/IL-1β signaling pathway.

Bifidobacterium dentium-derived y-glutamylcysteine suppresses ER-mediated goblet cell stress and reduces TNBS-driven colonic inflammation

Endoplasmic reticulum (ER) stress compromises the secretion of MUC2 from goblet cells and has been linked with inflammatory bowel disease (IBD). Although Bifidobacterium can beneficially modulate mucin production, little work has been done investigating the effects of Bifidobacterium on goblet cell ER stress. We hypothesized that secreted factors from Bifidobacterium dentium downregulate ER stress genes and modulates the unfolded protein response (UPR) to promote MUC2 secretion. We identified by mass spectrometry that B. dentium secretes the antioxidant γ-glutamylcysteine, which we speculate dampens ER stress-mediated ROS and minimizes ER stress phenotypes. B. dentium cell-free supernatant and γ-glutamylcysteine were taken up by human colonic T84 cells, increased glutathione levels, and reduced ROS generated by the ER-stressors thapsigargin and tunicamycin. Moreover, B. dentium supernatant and γ-glutamylcysteine were able to suppress NF-kB activation and IL-8 secretion. We found that B. dentium supernatant, γ-glutamylcysteine, and the positive control IL-10 attenuated the induction of UPR genes GRP78, CHOP, and sXBP1. To examine ER stress in vivo, we first examined mono-association of B. dentium in germ-free mice which increased MUC2 and IL-10 levels compared to germ-free controls. However, no changes were observed in ER stress-related genes, indicating that B. dentium can promote mucus secretion without inducing ER stress. In a TNBS-mediated ER stress model, we observed increased levels of UPR genes and pro-inflammatory cytokines in TNBS treated mice, which were reduced with addition of live B. dentium or γ-glutamylcysteine. We also observed increased colonic and serum levels of IL-10 in B. dentium- and γ-glutamylcysteine-treated mice compared to vehicle control. Immunostaining revealed retention of goblet cells and mucus secretion in both B. dentium- and γ-glutamylcysteine-treated animals. Collectively, these data demonstrate positive modulation of the UPR and MUC2 production by B. dentium-secreted compounds.

Colon-targeted drug delivery of polysaccharide-based nanocarriers for synergistic treatment of inflammatory bowel disease: A review

Drugs such as immunosuppressants and glucocorticoids used for the treatment of inflammatory bowel disease (IBD) have certain troubling side effects. Polysaccharide-based nanocarriers with high safety and bioavailability are often used in the construction of colon-targeted drug nanodelivery systems (DNSs). It can help the drug resist the harsh environment of gastrointestinal tract, improve stability and concentrate on the intestinal inflammation regions as much as possible, which effectively reduces drug side effects and enhances its bioavailability. Certain polysaccharides, as prebiotics, can not only endow DNSs with the ability to target the colon based on enzyme responsive properties, but also cooperate with drugs to alleviate IBD due to its good anti-inflammatory activity and intestinal microecological regulation. The changes in the gastrointestinal environment of patients with IBD, the colon-targeted drug delivery process of polysaccharide-based nanocarriers and its synergistic treatment mechanism for IBD were reviewed. Polysaccharides used in polysaccharide-based nanocarriers for IBD were summarized.

The risk of revision following total hip arthroplasty in patients with inflammatory bowel disease, a registry based study

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the intestinal tract and is associated with decreased bone mineral density. IBD patients are at higher risk of osteopenia, osteoporosis and fracture compared to non-IBD patients. The impact of IBD on the performance of orthopedic implants has not been well studied. We hypothesized that a history of IBD at the time of primary total hip arthroplasty (THA) would increase the risk of subsequent failure as assessed by revision surgery. A retrospective implant survival analysis was completed using the Swedish Hip Arthroplasty Registry and the Sweden National Patient Register. A total of 150,073 patients undergoing THA for osteoarthritis within an 18-year period were included in the study. THA patients with (n = 2,604) and without (n = 147,469) a history of IBD at the time of THA were compared with primary revision as the main endpoint and adjusted using sex, age category and comorbidity (Elixhauser scores) as covariates. We found that patients with a history of IBD had a relatively higher risk of revision surgery for septic causes while the non-IBD patients had a relatively higher risk of revision for aseptic causes (p = 0.004). Our findings suggest there may be an association between gut health and THA performance.

Altered Mucus Barrier Integrity and Increased Susceptibility to Colitis in Mice upon Loss of Telocyte Bone Morphogenetic Protein Signalling

FoxL1+-Telocytes (TCFoxL1+) are subepithelial cells that form a network underneath the epithelium. We have shown that without inflammatory stress, mice with loss of function in the BMP signalling pathway in TCFoxL1+ (BmpR1aΔFoxL1+) initiated colonic neoplasia. Although TCFoxL1+ are modulated in IBD patients, their specific role in this pathogenesis remains unclear. Thus, we investigated how the loss of BMP signalling in TCFoxL1+ influences the severity of inflammation and fosters epithelial recovery after inflammatory stress. BmpR1a was genetically ablated in mouse colonic TCFoxL1+. Experimental colitis was performed using a DSS challenge followed by recovery steps to assess wound healing. Physical barrier properties, including mucus composition and glycosylation, were assessed by alcian blue staining, immunofluorescences and RT-qPCR. We found that BmpR1aΔFoxL1+ mice had impaired mucus quality, and upon exposure to inflammatory challenges, they had increased susceptibility to experimental colitis and delayed healing. In addition, defective BMP signalling in TCFoxL1+ altered the functionality of goblet cells, thereby affecting mucosal structure and promoting bacterial invasion. Following inflammatory stress, TCFoxL1+ with impaired BMP signalling lose their homing signal for optimal distribution along the epithelium, which is critical in tissue regeneration after injury. Overall, our findings revealed key roles of BMP signalling in TCFoxL1+ in IBD pathogenesis.

The role of oral bacteria in inflammatory bowel disease

Over the past two decades, the importance of the microbiota in health and disease has become evident. Pathological changes to the oral bacterial microbiota, such as those occurring during periodontal disease, are associated with multiple inflammatory conditions, including inflammatory bowel disease. However, the degree to which this association is a consequence of elevated oral inflammation or because oral bacteria can directly drive inflammation at distal sites remains under debate. In this Perspective, we propose that in inflammatory bowel disease, oral disease-associated bacteria translocate to the intestine and directly exacerbate disease. We propose a multistage model that involves pathological changes to the microbial and immune compartments of both the oral cavity and intestine. The evidence to support this hypothesis is critically evaluated and the relevance to other diseases in which oral bacteria have been implicated (including colorectal cancer and liver disease) are discussed.

Ageratina adenophora Disrupts the Intestinal Structure and Immune Barrier Integrity in Rats

The aim of this study was to investigate the effects of Ageratina adenophora on the intestines morphology and integrity in rat. Rats were randomly divided into two groups and were fed with 10 g/100 g body weight (BW) basal diet and 10 g/100 g BW experimental diet, which was a mixture of A. adenophora powder and basal diet in a 3:7 ratio. The feeding experiment lasted for 60 days. At days 28 and 60 of the experiment, eight rats/group/timepoint were randomly selected, weighed, and sacrificed, then blood and intestinal tissues were collected and stored for further analysis. The results showed that Ageratina adenophora caused pathological changes and injury in the intestine, elevated serum diamine oxidase (DAO), D-lactate (D-LA), and secretory immunoglobulin A (sIgA) levels, reduced occludin levels in intestinal tissues, as well as increased the count of intraepithelial leukocytes (IELs) and lamina propria leukocytes (LPLs) in the intestine (p < 0.05 or p < 0.01). In addition, the mRNA and protein (ELISA) expressions of pro-inflammation cytokines (IL-1β, IL-2, TNF-α, and IFN-ϒ) were elevated in the Ageratina adenophora treatment groups, whereas anti-inflammatory cytokines such as IL-4 and IL-10 were reduced (p < 0.01 or p < 0.05). Therefore, the results obtained in this study indicated that Ageratina adenophora impaired intestinal function in rats by damaging the intestine structure and integrity, and also triggered an inflammation immune response that led to intestinal immune barrier dysfunction.

Ferulic Acid Metabolites Attenuate LPS-Induced Inflammatory Response in Enterocyte-like Cells

Ferulic acid (FA) is a polyphenol pertaining to the class of hydroxycinnamic acids present in numerous foods of a plant origin. Its dietary consumption leads to the formation of several phase I and II metabolites in vivo, which represent the largest amount of ferulates in the circulation and in the intestine in comparison with FA itself. In this work, we evaluated their efficacy against the proinflammatory effects induced by lipopolysaccharide (LPS) in intestinal Caco-2 cell monolayers, as well as the mechanisms underlying their protective action. LPS-induced overexpression of proinflammatory enzymes such as inducible nitric oxide synthase (iNOS) and the consequent hyperproduction of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) were limited by physiological relevant concentrations (1 µM) of FA, its derivatives isoferulic acid (IFA) and dihydroferulic acid (DHFA), and their glucuronidated and sulfated metabolites, which acted upstream by limiting the activation of MAPK p38 and ERK and of Akt kinase, thus decreasing the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB) translocation into the nucleus. Furthermore, the compounds were found to promote the expression of Nrf2, which may have contributed to the downregulation of NF-ĸB activity. The overall data show that phase I/II metabolites retain the efficacy of their dietary free form in contrasting inflammatory response.

Organoids and Their Use in Modeling Gut Epithelial Cell Lineage Differentiation and Barrier Properties During Intestinal Diseases

Maintenance of intestinal epithelium homeostasis is a complex process because of the multicellular and molecular composition of the gastrointestinal wall and the involvement of surrounding interactive signals. The complex nature of this intestinal barrier system poses challenges in the detailed mechanistic understanding of intestinal morphogenesis and the onset of several gut pathologies, including intestinal inflammatory disorders, food allergies, and cancer. For several years, the gut scientific community has explored different alternatives in research involving animals and in vitro models consisting of cultured monolayers derived from the immortalized or cancerous origin cell lines. The recent ability to recapitulate intestinal epithelial dynamics from mini-gut cultures has proven to be a promising step in the field of scientific research and biomedicine. The organoids can be grown as two- or three-dimensional structures, and are derived from adult or pluripotent stem cells that ultimately establish an intestinal epithelium that is composed of all differentiated cell types present in the normal epithelium. In this review, we summarize the different origins and recent use of organoids in modeling intestinal epithelial differentiation and barrier properties.

Titanium dioxide particles from the diet: involvement in the genesis of inflammatory bowel diseases and colorectal cancer

The gastrointestinal tract is a complex interface between the external environment and the immune system. Its ability to control uptake across the mucosa and to protect the body from damage of harmful substances from the lumen is defined as the intestinal barrier function (IBF). The IBF involves four elements: the intestinal microbiota, the mucus layer, the epithelium and the immune system. Its dysfunction is linked with human diseases including inflammatory, metabolic, infectious, autoimmune and neurologic disorders. Most of these diseases are complex and involve genetic, psychological and environmental factors. Over the past 10 years, many genetic polymorphisms predisposing to inflammatory bowel disease (IBD) have been identified. Yet, it is now clear that they are insufficient to explain the onset of these chronic diseases. Although it has been evidenced that some environmental factors such as cigarette smoking or carbohydrate intake are associated with IBD, other environmental factors also present potential health risks such as ingestion of food additives introduced in the human diet, including those composed of mineral particles, by altering the four elements of the intestinal barrier function. The aim of this review is to provide a critical opinion on the potential of TiO₂ particles, especially when used as a food additive, to alter the four elements of the intestinal barrier function, and consequently to evaluate if this additive would likely play a role in the development and/or exacerbation of IBD.

Comparative study of the laxative effects of konjac oligosaccharides and konjac glucomannan on loperamide-induced constipation in rats

Dietary fiber is the basic therapeutic method to relieve the symptoms of chronic constipation. The aim of this study was to compare the laxative effect of konjac glucomannan (KGM) and konjac oligosaccharides (KOS) on constipated rats. KGM and KOS were administered to loperamide-induced constipated rats at dosages of 100 mg per kg bw and 400 mg per kg bw for 15 days. Feces were collected to evaluate the defecation function. X-ray imaging and an electrophysiological system were used to determine gastrointestinal (GI) motility. Immunohistochemistry and western blotting were used to measure the protein levels. Magnetic resonance imaging (MRI) was performed to assess flatulence. Our results demonstrated that low-dose KOS (L-KOS) exerted the best laxative effect. Compared to the normal control (NC) group, the fecal number in the L-KOS group increased by 39.4%, and the fecal weight significantly increased by 31.9% which was higher than those in the low-dose KGM (L-KGM) and high-dose KGM (H-KGM) groups. The fecal moisture content and transit scores were significantly increased only in the L-KOS group. Meanwhile, less GI gas was produced by KOS. Additionally, further investigations suggested that KOS could upregulate the protein expression of stem cell factors (SCF)/c-kit, and significantly promoted the secretion of mucus. In conclusion, compared to KGM, KOS had a conspicuous laxative effect especially at a low dosage. The potential laxative mechanisms of KOS probably are regulating the SCF/c-kit signalling pathway and increasing mucus secretion. These findings indicated that as a kind of functional oligosaccharide, KOS is more conducive to alleviating constipation compared to polysaccharides.

Lactose-Gated Mesoporous Silica Particles for Intestinal Controlled Delivery of Essential Oil Components: An In Vitro and In Vivo Study

Mesoporous silica microparticles functionalized with lactose for the specific release of essential oil components (EOCs) in the small intestine are presented. In vitro and in vivo intestinal models were applied to validate the microparticles (M41-EOC-L), in which the presence of lactase acts as the triggering stimulus for the controlled release of EOCs. Among the different microdevices prepared (containing thymol, eugenol and cinnamaldehyde), the one loaded with cinnamaldehyde showed the most significant Caco-2 cell viability reduction. On the other hand, interaction of the particles with enterocyte-like monolayers showed a reduction of EOCs permeability when protected into the designed microdevices. Then, a microdevice loaded with cinnamaldehyde was applied in the in vivo model of Wistar rat. The results showed a reduction in cinnamaldehyde plasma levels and an increase in its concentration in the lumen of the gastrointestinal tract (GIT). The absence of payload release in the stomach, the progressive release throughout the intestine and the prolonged stay of the payload in the GIT-lumen increased the bioavailability of the encapsulated compound at the site of the desired action. These innovative results, based on the specific intestinal controlled delivery, suggest that the M41-payload-L could be a potential hybrid microdevice for the protection and administration of bioactive molecules in the small intestine and colon.

Current Strategies and Potential Prospects of Nanomedicine-Mediated Therapy in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) such as Crohn's disease and ulcerative colitis are highly debilitating. IBDs are associated with the imbalance of inflammatory mediators within the inflamed bowel. Conventional drugs for IBD treatment include anti-inflammatory medications and immune suppressants. However, they suffer from a lack of bioavailability and high dose-induced systemic side effects. Nanoparticle (NP)-derived therapy improves therapeutic efficacy and increases targeting specificity. Recent studies have shown that nanomedicines, based on bowel disease's pathophysiology, are a fast-growing field. NPs can prolong the circulation period and reduce side effects by improving drug encapsulation and targeted delivery. Here, this review summarizes various IBD therapies with a focus on NP-derived applications, whereas their challenges and future perspectives have also been discussed.

Disruption of the pro-inflammatory, anti-inflammatory cytokines and tight junction proteins expression, associated with changes of the composition of the gut microbiota in patients with irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a pathologic condition characterized by changes in gut microbiome composition, low-grade inflammation, and disruption of intestinal wall permeability. The interaction between the gut microbiome and the disease manifestation remains unclear. The changing of tight junction proteins and cytokines expression throughout the gastrointestinal tract in IBS patients has not been studied yet.

AIM OF THE STUDY

To assess the changes of gut microbiome composition, tight junction proteins, and cytokines expression of intestinal mucosa from the duodenum to the distal part of the colon in IBS patients and healthy volunteers.

METHODS

In 31 IBS patients (16 patients with IBS-D; 15 patients with IBS-C) and 10 healthy volunteers the expression of CLD-2, CLD-3, CLD-5, IL-2, IL-10, and TNF-α in mucosal biopsy specimens was determined by morphological and immune-histochemical methods. The qualitative and quantitative composition of the intestinal microbiota was assessed based on 16S rRNA gene sequencing in both groups of patients.

RESULTS

The expression of IL-2 and TNF-α was significantly increased in IBS patients compared with the controls (p<0.001), with a gradual increase from the duodenum to the sigmoid colon. The expression of IL-10, CLD-3, and CLD-5 in mucosal biopsy specimens of these patients was lower than in the control group (p<0.001). Increased ratios of Bacteroidetes and decreased ratios of Firmicutes were noted in IBS patients compared to healthy volunteers (p<0.05).

CONCLUSION

IBS patients have impaired gut permeability and persisting low-grade inflammation throughout the gastrointestinal tract. Changes in the gut microbiota may support or exacerbate these changes.

Ovomucin Ameliorates Intestinal Barrier and Intestinal Bacteria to Attenuate DSS-Induced Colitis in Mice

Egg white ovomucin (OVM) is homologically related to MUC2, the key component of colonic mucous layer. This study investigated the effects of orally administered OVM from egg white on the colonic mucosal barrier and the development of colitis using a colitis C57BL/6J mice model. The results showed that daily supplementation of 125 and 250 mg/kg BW of OVM partially relieved the villous destruction and loss of intestinal barrier integrity, and hence decreased the epithelial barrier permeability. The supplementation also reduced the secretion of proinflammatory cytokines TNF-α and IL-6. Besides, OVM administration significantly increased the relative abundance of intestinal beneficial bacteria including Lactobacilli, Faecalibaculum, Ruminococcus, etc. and further upregulated the production of bacterial metabolites such as short-chain fatty acids (SCFAs), which is a direct source of energy for the proliferation of epithelia and goblet cells. In conclusion, OVM from egg white ameliorates colitis by enhancing the intestinal barrier function and abundance of intestinal bacteria, thereby increasing the number of SCFAs.

An IFN-STAT Axis Augments Tissue Damage and Inflammation in a Mouse Model of Crohn's Disease

Blocking interferon-function by therapeutic intervention of the JAK-STAT-axis is a novel promising treatment option for inflammatory bowel disease (IBD). Although JAK inhibitors have proven efficacy in patients with active ulcerative colitis (UC), they failed to induce clinical remission in patients with Crohn's disease (CD). This finding strongly implicates a differential contribution of JAK signaling in both entities. Here, we dissected the contribution of different STAT members downstream of JAK to inflammation and barrier dysfunction in a mouse model of Crohn's disease like ileitis and colitis (Casp8^ΔIEC mice). Deletion of STAT1 in Casp8^ΔIEC mice was associated with reduced cell death and a partial rescue of Paneth cell function in the small intestine. Likewise, organoids derived from the small intestine of these mice were less sensitive to cell death triggered by IBD-key cytokines such as TNFα or IFNs. Further functional in vitro and in vivo analyses revealed the impairment of MLKL-mediated necrosis as a result of deficient STAT1 function, which was in turn associated with improved cell survival. However, a decrease in inflammatory cell death was still associated with mild inflammation in the small intestine. The impact of STAT1 signaling on gastrointestinal inflammation dependent on the localization of inflammation, as STAT1 is essential for intestinal epithelial cell death regulation in the small intestine, whereas it is not the key factor for intestinal epithelial cell death in the context of colitis. Of note, additional deletion of STAT2 was not sufficient to restore Paneth cell function but strongly ameliorated ileitis. In summary, we provide here compelling molecular evidence that STAT1 and STAT2, both contribute to intestinal homeostasis, but have non-redundant functions. Our results further demonstrate that STATs individually affect the distinct pathophysiology of inflammation in the ileum and colon, respectively, which might explain the diverse outcome of JAK inhibitors on inflammatory bowel diseases.

Control of Intestinal Epithelial Permeability by Lysophosphatidic Acid Receptor 5

BACKGROUND & AIMS

Epithelial cells form a monolayer at mucosal surface that functions as a highly selective barrier. Lysophosphatidic acid (LPA) is a bioactive lipid that elicits a broad range of biological effects via cognate G protein-coupled receptors. LPA receptor 5 (LPA₅) is highly expressed in intestinal epithelial cells, but its role in the intestine is not well-known. Here we determined the role of LPA₅ in regulation of intestinal epithelial barrier.

METHODS

Epithelial barrier integrity was determined in mice with intestinal epithelial cell (IEC)-specific LPA₅ deletion, Lpar5^ΔIEC. LPA was orally administered to mice, and intestinal permeability was measured. Dextran sulfate sodium (DSS) was used to induce colitis. Human colonic epithelial cell lines were used to determine the LPA₅-mediated signaling pathways that regulate epithelial barrier.

RESULTS

We observed increased epithelial permeability in Lpar5^ΔIEC mice with reduced claudin-4 expression. Oral administration of LPA decreased intestinal permeability in wild-type mice, but the effect was greatly mitigated in Lpar5^ΔIEC mice. Serum lipopolysaccharide level and bacterial loads in the intestine and liver were elevated in Lpar5^ΔIEC mice. Lpar5^ΔIEC mice developed more severe colitis induced with DSS. LPA₅ transcriptionally regulated claudin-4, and this regulation was dependent on transactivation of the epidermal growth factor receptor, which induced localization of Rac1 at the cell membrane. LPA induced the translocation of Stat3 to the cell membrane and promoted the interaction between Rac1 and Stat3. Inhibition of Stat3 ablated LPA-mediated regulation of claudin-4.

CONCLUSIONS

This study identifies LPA₅ as a regulator of the intestinal barrier. LPA₅ promotes claudin-4 expression in IECs through activation of Rac1 and Stat3.

Effect of Size and Loading of Retinoic Acid in Polyvinyl Butyrate Nanoparticles on Amelioration of Colitis

Butyrate has been used in the treatment of inflammatory bowel diseases (IBD). However, the controlled release of butyrate has been indicated to be necessary in order to avoid the side effects verified at high concentrations. We previously developed nanoparticles (NPs) of polyvinyl butyrate (PVBu) as an oral butyrate donor for the controlled release of butyrate for the treatment of colitis. To examine the effect of the size of NPs on the therapeutic effect of colitis, here we prepared PVBu NPs with different sizes (100 nm and 200 nm). Both sizes of PVBu NPs significantly suppressed the inflammatory response in macrophages in vitro. PVBu NPs with 200 nm showed better effects on the amelioration of colitis compared with the 100 nm-NPs. We found unexpectedly that 200 nm-NP incorporated with all-trans retinoic acid (ATRA) showed a much better therapeutic effect than those with unloaded 200 nm-NPs, although ATRA alone was reported to worsen the inflammation. The synergistic effect of ATRA with butyrate shows evidence of being a promising approach for IBD treatment.

Interleukin-28A induces epithelial barrier dysfunction in CD patient-derived intestinal organoids

Intestinal barrier dysfunction is a pathogenic hallmark in Crohn's disease (CD). Identifying key players that regulate intestinal barrier may provide novel leads for therapeutic intervention. Interleukin-28A (IL-28A) is a newly identified IL-10/interferon cytokine family member, with its most implicated function being antiviral and anti-proliferative properties. However, the role and underlying mechanisms of IL-28A in the regulation of epithelial barrier in CD remain so far unexplored. IL-28A levels were measured in the plasma and biopsies of CD patients and healthy subjects. CD patient-derived intestinal organoids were characterized by differentiation gene markers and then exposed to TNF-α, IFN-γ, IL-1β or LPS, or IL-28A with or without GLPG0634 (filgotinib). Epithelial permeability was assessed by FITC-D4 flux. Expression of junctional components was analyzed by qRT-PCR, immunofluorescence staining, or Western blotting. JAK-STAT activity was analyzed by Western blotting. IL-28A levels were significantly increased in the plasma and biopsies from active patients with CD as compared with healthy subjects. IL-28A and its receptor complex IL-28AR/IL-10R2 were detected in CD patient-derived intestinal organoids and showed a selective response to IFN-γ exposure. IL-28A triggered epithelial barrier disruption and accompanied by reduced ZO-1 and E-cadherin expression. This effect was mediated by JAK-STAT1 pathway. Pre-incubation with the JAK1 inhibitor filgotinib ameliorated the barrier dysfunction induced by IL-28A. These results identified IL-28A as a novel regulator of epithelial barrier function and could be a putative target for CD treatment. We provide novel basic evidence that restoring intestinal barrier is a potential mechanism that contributes to the clinical benefits of JAK1 inhibitor in patients with CD.NEW & NOTEWORTHY IL-28A levels were significantly increased in the plasma and biopsies from active patients with CD as compared with healthy subjects. IFN-γ exposure stimulated IL-28A expression in intestinal organoids. Partially mimicking the effect of IFN-γ, IL-28A impaired epithelial barrier function and disrupted junctional components through the activation of JAK-STAT1 signaling, whereas JAK1 inhibitor ameliorated the above-mentioned effects of IL-28A. These findings highlight the newly identified cytokine IL-28A as a novel contributor to CD pathogenesis and could be a putative target for CD treatment. We also provide new evidence for potential applications of JAK inhibition in CD therapy.

Effect of Promoter Methylation on the Expression of Porcine MUC2 Gene and Resistance to PEDV Infection

Integrity of the intestinal mucosal barrier is closely related to the occurrence of diarrhea. As an important component protein of the intestinal mucosal barrier, Mucin 2 (MUC2) plays a critical role in preventing the invasion of pathogens, toxins, and foreign bodies. In the present study, we preliminary verified the function of the porcine MUC2 gene in resisting porcine epidemic diarrhea virus (PEDV) infection and investigated the effect of DNA methylation in the promoter region on MUC2 gene expression. The results showed that after PEDV infection, the intestinal mucosal barrier was damaged. Moreover, MUC2 expression was significantly higher in PEDV-infected piglets than in healthy piglets (P < 0.01). The mRNA expression of MUC2 was significantly higher in PEDV-infected IPEC-J2 cells than in non-infected IPEC-J2 cells (P < 0.05). Methylation of the mC-5 site in the MUC2 promoter inhibited the binding of Yin Yang 1 (YY1) to the promoter, down regulated the expression of MUC2 and increased the susceptibility of piglets to PEDV. In conclusion, this study suggests that MUC2 plays an essential regulatory role in PEDV infection. High MUC2 expression improves the resistance of pigs to PEDV infection. The binding of YY1 to the MUC2 promoter is hindered by the methylation of the mC-5 site, which downregulates MUC2 expression and ultimately affects the resistance of pigs to PEDV infection.

Blockade of TLRs-triggered macrophage activation by caffeic acid exerted protective effects on experimental ulcerative colitis

Ulcerative colitis (UC) represents a relapsing and inflammatory bowel disease which is commonly linked with the communications between dysfunction of epithelium and mucosal immune responses. Though caffeic acid (CA) has numerous pharmacological capacities, whether CA demonstrates immunoregulation on the mucosal immune responses remains ill-defined. Herein, the present research demonstrated that CA could dramatically attenuate the mucosal inflammation, as evidenced by improving the disease severity, serum biochemical indexes, mucosal ulcerations, loss of epithelium and crypts, and secretion of inflammatory cytokines in the colonic homogenates and explants culture. Consistently, CA could interfere with the infiltration and function of mononuclear macrophages in the mucosa, MLNs, and spleens of UC. Furthermore, CA exerted direct suppressive effects on the activation of BMDMs upon the exposure of TLRs agonists in vitro. Taken together, CA could attenuate DSS-induced murine UC through interfering with the activation of macrophages, which might provide an alternative therapeutic option for UC.

Cell surface and extracellular proteins of potentially probiotic Lactobacillus reuteri as an effective mediator to regulate intestinal epithelial barrier function

The present study aimed to evaluate the potential of cell surface and extracellular proteins in regulation of intestinal epithelial barrier (IEB) function. Eight potentially probiotic L. reuteri strains were evaluated for presence of mapA gene and its expression on co-culturing with the Caco-2 cells. The ability of untreated (Viable), heat-inactivated, 5 M LiCL treated L. reuteri strains as well as their cell-free supernatant (CFS) to modulate expression of IEB function genes (hBD-2, hBD-3, claudin-1 and occludin) was also evaluated. Caco-2 cells were treated with cell surface and extracellular protein extracts and investigated for change in expression of targeted IEB function genes. The results showed that mapA gene is present in all the tested L. reuteri strains and expression of mapA and its receptors (anxA13 and palm) increase significantly on co-culturing of L. reuteri and Caco-2 cells. Also, up-regulated expression of IEB function genes was observed on co-culturing of L. reuteri (viable, heat-inactivated and CFS) and their protein extracts with Caco-2 cells in contrast to down-regulation observed with the pathogenic strain of Salmonella typhi. Therefore, this study concludes that the cell surface and extracellular protein from L. reuteri act as an effective mediator molecules to regulate IEB function.

Coptisine ameliorates DSS-induced ulcerative colitis via improving intestinal barrier dysfunction and suppressing inflammatory response

Ulcerative colitis (UC), as an autoimmune disease, has been troubling human health for many years. Up to now, the available treatments remain unsatisfactory. Rhizoma Coptidis has been widely applied to treat gastrointestinal diseases in China for a long time, and coptisine (COP) is identified as one of its major active components. This study aimed to evaluate the bioactivity of COP on dextran sulfate sodium (DSS)-induced mice colitis and clarify the potential mechanism of action. The results revealed that COP treatment markedly alleviated DSS-induced clinical symptoms by relieving body weight loss and the disease activity index (DAI) score. Specifically, the colon length in the COP (50 and 100 mg/kg) groups were obviously longer than that in the DSS group (7.21 ± 0.34, 8.59 ± 0.45 cm vs. 6.71 ± 0.59 cm, P < 0.01). HE staining analysis revealed that COP treatment significantly protected the integrity of intestinal barrier and alleviated inflammatory cells infiltration. Western blot assay confirmed that COP notably improved the intestinal epithelial barrier function by enhancing the expressions of colonic tight junction proteins and inhibited the expressions of apoptosis-related proteins. In addition, COP treatment remarkably suppressed the levels of colonic myeloperoxidase (MPO), adhesion molecules and pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1β, IL-6 and IL-17), while enhanced IL-10 and TGF-β. The mechanism anti-inflammatory of COP might be related to inhibiting the phosphorylation of IκBα, and the translocation of NF-κB p65 from cytoplasm to nucleus. In summary, the study indicated that COP ameliorated DSS-induced colitis, at least partly through maintaining the integrity of intestinal epithelial barrier, inhibiting apoptosis and inflammatory response.

Tremella fuciformis Polysaccharides Inhibited Colonic Inflammation in Dextran Sulfate Sodium-Treated Mice via Foxp3+ T Cells, Gut Microbiota, and Bacterial Metabolites

Tremella fuciformis is an edible medicinal mushroom, and its polysaccharide components are found to confer various health benefits. This study identified the protective effects of polysaccharides of Tremella fuciformis (TPs) against dextran sulfate sodium (DSS)-induced colitis in mice. High dose of TPs (HTPs) could prevent the colon from shortening, reduce activity of colonic myeloperoxidase and serum diamine oxidase (DAO), decrease the concentration of D-lactate, and alleviate the colonic tissue damage in colitic mice. HTPs treatment stimulated Foxp3+T cells, and promoted the production of anti-inflammatory cytokines whereas it reduced the production of pro-inflammatory and the portion of immunoglobulin A (IgA)-coated bacteria, which was related to modulation of immune responses. 16S rRNA sequencing analysis showed that TPs could significantly increase gut community diversity, and restore the relative abundances of Lactobacillus, Odoribacter, Helicobacter, Ruminococcaceae, and Marinifilaceae. According to metabolomic analysis, HTPs induced specific microbial metabolites akin to that in normal mice. Tyrosine biosynthesis, tryptophan metabolism, and bile acid metabolism were influenced in the HTPs group compared with those in the DSS group. HTPs could alleviate DSS-induced colitis by immunoregulation and restored the gut microbiota and microbial metabolites. The results indicated that HTPs have potential to be developed as a food supplement to ameliorate intestinal diseases.

Linking bacterial enterotoxins and alpha defensin 5 expansion in the Crohn's colitis: A new insight into the etiopathogenetic and differentiation triggers driving colonic inflammatory bowel disease

Evidence link bacterial enterotoxins to apparent crypt-cell like cells (CCLCs), and Alpha Defensin 5 (DEFA5) expansion in the colonic mucosa of Crohn's colitis disease (CC) patients. These areas of ectopic ileal metaplasia, positive for Paneth cell (PC) markers are consistent with diagnosis of CC. Retrospectively, we: 1. Identified 21 patients with indeterminate colitis (IC) between 2000-2007 and were reevaluation their final clinical diagnosis in 2014 after a followed-up for mean 8.7±3.7 (range, 4-14) years. Their initial biopsies were analyzed by DEFA5 bioassay. 2. Differentiated ulcer-associated cell lineage (UACL) analysis by immunohistochemistry (IHC) of the CC patients, stained for Mucin 6 (MUC6) and DEFA5. 3. Treated human immortalized colonic epithelial cells (NCM460) and colonoids with pure DEFA5 on the secretion of signatures after 24hr. The control colonoids were not treated. 4. Treated colonoids with/without enterotoxins for 14 days and the spent medium were collected and determined by quantitative expression of DEFA5, CCLCs and other biologic signatures. The experiments were repeated twice. Three statistical methods were used: (i) Univariate analysis; (ii) LASSO; and (iii) Elastic net. DEFA5 bioassay discriminated CC and ulcerative colitis (UC) in a cohort of IC patients with accuracy. A fit logistic model with group CC and UC as the outcome and the DEFA5 as independent variable differentiator with a positive predictive value of 96 percent. IHC staining of CC for MUC6 and DEFA5 stained in different locations indicating that DEFA5 is not co-expressed in UACL and is therefore NOT the genesis of CC, rather a secretagogue for specific signature(s) that underlie the distinct crypt pathobiology of CC. Notably, we observed expansion of signatures after DEFA5 treatment on NCM460 and colonoids cells expressed at different times, intervals, and intensity. These factors are key stem cell niche regulators leading to DEFA5 secreting CCLCs differentiation 'the colonic ectopy ileal metaplasia formation' conspicuously of pathogenic importance in CC.

Pancreatic glycoprotein 2 is a first line of defense for mucosal protection in intestinal inflammation

Increases in adhesive and invasive commensal bacteria, such as Escherichia coli, and subsequent disruption of the epithelial barrier is implicated in the pathogenesis of inflammatory bowel disease (IBD). However, the protective systems against such barrier disruption are not fully understood. Here, we show that secretion of luminal glycoprotein 2 (GP2) from pancreatic acinar cells is induced in a TNF-dependent manner in mice with chemically induced colitis. Fecal GP2 concentration is also increased in Crohn's diease patients. Furthermore, pancreas-specific GP2-deficient colitis mice have more severe intestinal inflammation and a larger mucosal E. coli population than do intact mice, indicating that digestive-tract GP2 binds commensal E. coli, preventing epithelial attachment and penetration. Thus, the pancreas-intestinal barrier axis and pancreatic GP2 are important as a first line of defense against adhesive and invasive commensal bacteria during intestinal inflammation.

The Interrelationships between Intestinal Permeability and Phlegm Syndrome and Therapeutic Potential of Some Medicinal Herbs

The gastrointestinal (GI) tract has an intriguing and critical role beyond digestion in both modern and complementary and alternative medicine (CAM), as demonstrated by its link with the immune system. In this review, we attempted to explore the interrelationships between increased GI permeability and phlegm, an important pathological factor in CAM, syndrome, and therapeutic herbs for two disorders. The leaky gut and phlegm syndromes look considerably similar with respect to related symptoms, diseases, and suitable herbal treatment agents, including phytochemicals even though limitations to compare exist. Phlegm may be spread throughout the body along with other pathogens via the disruption of the GI barrier to cause several diseases sharing some parts of symptoms, diseases, and mechanisms with leaky gut syndrome. Both syndromes are related to inflammation and gut microbiota compositions. Well-designed future research should be conducted to verify the interrelationships for evidence based integrative medicine to contribute to the promotion of public health. In addition, systems biology approaches should be adopted to explore the complex synergistic effects of herbal medicine and phytochemicals on conditions associated with phlegm and leaky gut syndromes.

Self-Nanoemulsifying Drug Delivery System of Genkwanin: A Novel Approach for Anti-Colitis-Associated Colorectal Cancer

PURPOSE

The aim of the present study was to develop an optimized Genkwanin (GKA)-loaded self-nanoemulsifying drug delivery system (SNEDDS) formulation to enhance the solubility, intestinal permeability, oral bioavailability and anti-colitis-associated colorectal cancer (CAC) activity of GKA.

METHODS

We designed a SNEDDS comprised oil phase, surfactants and co-surfactants for oral administration of GKA, the best of which were selected by investigating the saturation solubility, constructing pseudo-ternary phase diagrams, followed by optimizing thermodynamic stability, emulsification efficacy, self-nanoemulsification time, droplet size, transmission electron microscopy (TEM), drug release and intestinal permeability. In addition, the physicochemical properties and pharmacokinetics of GKA-SNEDDS were characterized, and its anti-colitis-associated colorectal cancer (CAC) activity and potential mechanisms were evaluated in AOM/DSS-induced C57BL/6J mice model.

RESULTS

The optimized nanoemulsion formula (OF) consists of Maisine CC, Labrasol ALF and Transcutol HP in a weight ratio of 20:60:20 (w/w/w), in which ratio the OF shows multiple improvements, specifically small mean droplet size, excellent stability, fast release properties as well as enhanced solubility and permeability. Pharmacokinetic studies demonstrated that compared with GKA suspension, the relative bioavailability of GKA-SNEDDS was increased by 353.28%. Moreover, GKA-SNEDDS not only significantly prevents weight loss and improves disease activity index (DAI) but also reduces the histological scores of inflammatory cytokine levels as well as inhibiting the formation of colon tumors via inducing tumor cell apoptosis in the AOM/DSS-induced CAC mice model.

CONCLUSION

Our results show that the developed GKA-SNEDDS exhibited enhanced oral bioavailability and excellent anti-CAC efficacy. In summary, GKA-SNEDDS, using lipid nanoparticles as the drug delivery carrier, can be applied as a potential drug delivery system for improving the clinical application of GKA.

Corticosteroid enhances epithelial barrier function in intestinal organoids derived from patients with Crohn's disease

Abstract

Corticosteroids (CS), first-line therapeutics for Crohn’s disease (CD) with moderate or severe disease activity, were found to restore intestinal permeability in CD patients, whereas the underlying molecular events are still largely unknown. This study aimed to investigate the effect and mechanisms of CS prednisolone on epithelial barrier using CD patient-derived intestinal organoids. 3D intestinal organoids were generated from colon biopsies of inactive CD patients. To mimic the inflammatory microenvironment, a mixture of cytokines containing TNF-α, IFN-γ, and IL-1β were added to the organoid culture with or without pre-incubation of prednisolone or mifepristone. Epithelial permeability of the organoids was assessed by FITC-D4 flux from the basal to luminal compartment using confocal microscopy. Expression of junctional components were analyzed by qRT-PCR, immunofluorescence staining, and western blot. Activity of signaling pathways were analyzed using western blot. Exposure of the cytokines significantly disrupted epithelial barrier of the intestinal organoids, which was partially restored by prednisolone. On the molecular level, the cytokine mixture resulted in a significant reduction in E-cadherin and ILDR-1, an increase in CLDN-2, MLCK, and STAT1 phosphorylation, whereas prednisolone ameliorated the abovementioned effects induced by the cytokine mixture. This study demonstrates that prednisolone confers a direct effect in tightening the epithelial barrier, identifies novel junctional targets regulated by prednisolone, and underscores intestinal barrier restoration as a potential mechanism that contributes to the clinical efficacy of prednisolone in CD patients.

Key messages

Prednisolone confers a direct preventive effect against cytokine-induced barrier dysfunction.

Prednisolone regulates the expression of CLDN-2, E-cadherin, and ILDR-1.

The effect of prednisolone is GR-, MLCK-, and STAT1-dependent.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00109-021-02045-7.

Berberine improves colitis by triggering AhR activation by microbial tryptophan catabolites

Inflammatory bowel diseases (IBD) are kind of recurrent inflammatory issues that occur in the gastrointestinal tract, and currently clinical treatment is still unideal due to the complex pathogenesis of IBD. Basically, gut barrier dysfunction is triggered by gut microbiota dysbiosis that is closely associated with the development of IBD, we thus investigated the therapeutic capacity of berberine (BBR) to improve the dysregulated gut microbiota, against IBD in rats, using a combinational strategy of targeted metabolomics and 16 s rDNA amplicon sequencing technology. Expectedly, our data revealed that BBR administration could greatly improve the pathological phenotype, gut barrier disruption, and the colon inflammation in rats with dextran sulfate sodium (DSS)-induced colitis. In addition, 16S rDNA-based microbiota analysis demonstrated that BBR could alleviate gut dysbiosis in rats. Furthermore, our targeted metabolomics analysis illustrated that the levels of microbial tryptophan catabolites in the gastrointestinal tract were significantly changed during the development of the colitis in rats, and BBR treatment can significantly restore such changes of the tryptophan catabolites accordingly. At last, our in vitro mechanism exploration was implemented with a Caco-2 cell monolayer model, which verified that the modulation of the dysregulated gut microbiota to change microbial metabolites coordinated the improvement effect of BBR on gut barrier disruption in the colitis, and we also confirmed that the activation of AhR induced by microbial metabolites is indispensable to the improvement of gut barrier disruption by BBR. Collectively, BBR has the capacity to treat DSS-induced colitis in rats through the regulation of gut microbiota associated tryptophan metabolite to activate AhR, which can greatly improve the disrupted gut barrier function. Importantly, our finding elucidated a novel mechanism of BBR to improve gut barrier function, which holds the expected capacity to promote the BBR derived drug discovery and development against the colitis in clinic setting.

Drug Disposition in the Lower Gastrointestinal Tract: Targeting and Monitoring

The increasing prevalence of colonic diseases calls for a better understanding of the various colonic drug absorption barriers of colon-targeted formulations, and for reliable in vitro tools that accurately predict local drug disposition. In vivo relevant incubation conditions have been shown to better capture the composition of the limited colonic fluid and have resulted in relevant degradation and dissolution kinetics of drugs and formulations. Furthermore, drug hurdles such as efflux transporters and metabolising enzymes, and the presence of mucus and microbiome are slowly integrated into drug stability- and permeation assays. Traditionally, the well characterized Caco-2 cell line and the Ussing chamber technique are used to assess the absorption characteristics of small drug molecules. Recently, various stem cell-derived intestinal systems have emerged, closely mimicking epithelial physiology. Models that can assess microbiome-mediated drug metabolism or enable coculturing of gut microbiome with epithelial cells are also increasingly explored. Here we provide a comprehensive overview of the colonic physiology in relation to drug absorption, and review colon-targeting formulation strategies and in vitro tools to characterize colonic drug disposition.

Gut Commensal-Induced IκBζ Expression in Dendritic Cells Influences the Th17 Response

Intestinal commensal bacteria can have a large impact on the state of health and disease of the host. Regulation of Th17 cell development by gut commensals is known to contribute to their dichotomous role in promoting gut homeostasis and host defense, or development of autoimmune diseases. Yet, the underlying mechanisms remain to be fully elucidated. One candidate factor contributing to Th17 differentiation, and the expression of which could be influenced by commensals is the atypical nuclear IκB protein IκBζ. IκBζ acts as a transcriptional regulator of the expression of Th17-related secondary response genes in many cell types including dendritic cells (DCs). Insights into the regulation of IκBζ in DCs could shed light on how these immune sentinel cells at the interface between commensals, innate and adaptive immune system drive an immune-tolerogenic or inflammatory Th17 cell response. In this study, the influence of two gut commensals of low (Bacteroides vulgatus) or high (Escherichia coli) immunogenicity on IκBζ expression in DCs and its downstream effects was analyzed. We observed that the amount of IκBζ expression and secretion of Th17-inducing cytokines correlated with the immunogenicity of these commensals. However, under immune-balanced conditions, E. coli also strongly induced an IκBζ-dependent secretion of anti-inflammatory IL-10, facilitating a counter-regulative Treg response as assessed in in vitro CD4⁺ T cell polarization assays. Yet, in an in vivo mouse model of T cell-induced colitis, prone to inflammatory and autoimmune conditions, administration of E. coli promoted an expansion of rather pro-inflammatory T helper cell subsets whereas administration of B. vulgatus resulted in the induction of protective T helper cell subsets. These findings might contribute to the development of new therapeutic strategies for the treatment of autoimmune diseases using commensals or commensal-derived components.

Inflammatory bowel disease is associated with higher dementia risk: a nationwide longitudinal study

OBJECTIVE

Increasing evidence supports reciprocal communication between the enteric and the central nervous system in disease, termed the 'gut-brain axis'. Recent findings suggest a connection between IBD and development of Parkinson's disease. The role of IBD in dementia, another insidious neurodegenerative disorder, has not been explored.

DESIGN

Using the Taiwanese National Health Insurance Research Database, we performed comparative analysis of 1742 patients with IBD ≥45 years old against 17 420 controls to assess dementia risk following IBD diagnosis. Controls were matched on bases of sex, access to healthcare, income and dementia-related comorbidities. All individuals were followed for dementia diagnosis for up to 16 years. Subanalyses included the relationship between sex, ulcerative colitis (UC) and Crohn's disease (CD), and dementia risk.

RESULTS

Overall incidence of dementia among patients with IBD was significantly elevated (5.5% vs 1.4% among controls). Patients with IBD were diagnosed with dementia at 76.24 years old on average, compared with 83.45 among controls. The HR of developing dementia among patients with IBD was 2.54 (95% CI 1.91 to 3.37). Among dementia types, the risk of developing Alzheimer's dementia demonstrated the greatest increase. Dementia risk did not differ between sex differences nor UC versus CD.

CONCLUSION

This population-based cohort study demonstrates significant association between IBD and subsequent development of dementia. Dementia was diagnosed at an earlier age among patients with IBD, and disease risk appeared to increase with IBD chronicity. These findings highlight the need for future research to elucidate the relationship between IBD and dementia.

The Protective Effect of E. faecium on S. typhimurium Infection Induced Damage to Intestinal Mucosa

Intensive farming is prone to induce large-scale outbreaks of infectious diseases, with increasing use of antibiotics, which deviate from the demand of organic farming. The high mortality rate of chickens infected with Salmonella caused huge economic losses; therefore, the promising safe prevention and treatment measures of Salmonella are in urgent need, such as probiotics. Probiotics are becoming an ideal alternative treatment option besides antibiotics, but the effective chicken probiotic strains with clear protective mechanism against Salmonella remain unclear. In this study, we found Enterococcus faecium YQH2 was effective in preventing Salmonella typhimurium infection in chickens. Salmonella typhimurium induced the loss of body weight, and liver and intestinal morphology damage. The inflammatory factor levels increased and intestinal proliferation inhibited. However, after treatment with Enterococcus faecium YQH2, broilers grew normally, the pathological changes of liver and intestine were reduced, and the colonization of Salmonella in the intestine was improved. Not only that, the length of villi and the depth of crypts were relatively normal, and the levels of inflammatory factors such as IL-1β, TNF-α, and IL-8 were reduced. The number of PCNA cells of Enterococcus faecium YQH2 returned to normal under the action of Salmonella typhimurium infection, which was conducive to the normal proliferation of intestinal epithelial cells. The protective effect of Enterococcus faecium YQH2 may be due to the attribution to the activation of hypoxia and then induced the proliferation of intestinal stem cells to repair the damage of intestinal mucosa under Salmonella typhimurium infection. This study demonstrated that Enterococcus faecium YQH2 was effective in preventing Salmonella typhimurium infection, which could be further used in the chicken health breeding.

Modeling Intestinal Epithelial Response to Interferon-γ in Induced Pluripotent Stem Cell-Derived Human Intestinal Organoids

Human intestinal organoids (HIOs) are increasingly being used to model intestinal responses to various stimuli, yet few studies have confirmed the fidelity of this modeling system. Given that the interferon-gamma (IFN-γ) response has been well characterized in various other cell types, our goal was to characterize the response to IFN-γ in HIOs derived from induced pluripotent stem cells (iPSCs). To achieve this, iPSCs were directed to form HIOs and subsequently treated with IFN-γ. Our results demonstrate that IFN-γ phosphorylates STAT1 but has little effect on the expression or localization of tight and adherens junction proteins in HIOs. However, transcriptomic profiling by microarray revealed numerous upregulated genes such as IDO1, GBP1, CXCL9, CXCL10 and CXCL11, which have previously been shown to be upregulated in other cell types in response to IFN-γ. Notably, "Response to Interferon Gamma" was determined to be one of the most significantly upregulated gene sets in IFN-γ-treated HIOs using gene set enrichment analysis. Interestingly, similar genes and pathways were upregulated in publicly available datasets contrasting the gene expression of in vivo biopsy tissue from patients with IBD against healthy controls. These data confirm that the iPSC-derived HIO modeling system represents an appropriate platform to evaluate the effects of various stimuli and specific environmental factors responsible for the alterations in the intestinal epithelium seen in various gastrointestinal conditions such as inflammatory bowel disease.

Inflammatory Bowel Disease: The Emergence of New Trends in Lifestyle and Nanomedicine as the Modern Tool for Pharmacotherapy

The human intestine, which harbors trillions of symbiotic microorganisms, may enter into dysbiosis when exposed to a genetic defect or environmental stress. The naissance of chronic inflammation due to the battle of the immune system with the trespassing gut bacteria leads to the rise of inflammatory bowel disease (IBD). Though the genes behind the scenes and their link to the disease are still unclear, the onset of IBD occurs in young adults and has expanded from the Western world into the newly industrialized countries. Conventional drug deliveries depend on a daily heavy dosage of immune suppressants or anti-inflammatory drugs targeted for the treatment of two types of IBD, ulcerative colitis (UC) and Crohn's disease (CD), which are often associated with systemic side effects and adverse toxicities. Advances in oral delivery through nanotechnology seek remedies to overcome the drawbacks of these conventional drug delivery systems through improved drug encapsulation and targeted delivery. In this review, we discuss the association of genetic factors, the immune system, the gut microbiome, and environmental factors like diet in the pathogenesis of IBD. We also review the various physiological concerns required for oral delivery to the gastrointestinal tract (GIT) and new strategies in nanotechnology-derived, colon-targeting drug delivery systems.

Mucin-2 knockout is a model of intercellular junction defects, mitochondrial damage and ATP depletion in the intestinal epithelium

The disruption of the protective intestinal barrier—the ‘leaky gut’—is a common complication of the inflammatory bowel disease. There is limited data on the mechanisms of the intestinal barrier disruption upon low-grade inflammation characteristic of patients with inflammatory bowel disease in clinical remission. Thus, animal models that recapitulate the complexity of chronic intestinal inflammation in vivo are of particular interest. In this study, we used Mucin-2 (Muc2) knockout mice predisposed to colitis to study intestinal barrier upon chronic inflammation. We used 4-kDa FITC-Dextran assay and transmission electron microscopy to demonstrate the increased intestinal permeability and morphological defects in intercellular junctions in Muc2 knockout mice. Confocal microscopy revealed the disruption of the apical F-actin cytoskeleton and delocalization of tight junction protein Claudin-3 from the membrane. We further demonstrate mitochondrial damage, impaired oxygen consumption and the reduction of the intestinal ATP content in Muc2 knockout mice. Finally, we show that chemically induced mitochondrial uncoupling in the wild type mice mimics the intestinal barrier disruption in vivo and causes partial loss of F-actin and membrane localization of Claudin-3. We propose that mitochondrial damage and metabolic shifts during chronic inflammation contribute to the leaky gut syndrome in Muc2 knockout animal model of colitis.

A critical role of endothelial cell protein C receptor in the intestinal homeostasis in experimental colitis

Crohn’s disease and ulcerative colitis are the two forms of disorders of the human inflammatory bowel disease with unknown etiologies. Endothelial cell protein C receptor (EPCR) is a multifunctional and multiligand receptor, which is expressed on the endothelium and other cell types, including epithelial cells. Here, we report that EPCR is expressed in the colon epithelial cells, CD11c⁺, and CD21⁺/CD35⁺ myeloid cells surrounding the crypts in the colon mucosa. EPCR expression was markedly decreased in the colon mucosa during colitis. The loss of EPCR appeared to associate with increased disease index of the experimental colitis in mice. EPCR^−/− mice were more susceptible to dextran sulfate sodium (DSS)-induced colitis, manifested by increased weight loss, macrophage infiltration, and inflammatory cytokines in the colon tissue. DSS treatment of EPCR^−/− mice resulted in increased bleeding, bodyweight loss, anemia, fibrin deposition, and loss of colon epithelial and goblet cells. Administration of coagulant factor VIIa significantly attenuated the DSS-induced colon length shortening, rectal bleeding, bodyweight loss, and disease activity index in the wild-type mice but not EPCR^−/− mice. In summary, our data provide direct evidence that EPCR plays a crucial role in regulating the inflammation in the colon during colitis.

Ulcerative Colitis-Derived Colonoid Culture: A Multi-Mineral-Approach to Improve Barrier Protein Expression

BACKGROUND

Recent studies demonstrated that Aquamin®, a calcium-, magnesium-rich, multi-mineral natural product, improves barrier structure and function in colonoids obtained from the tissue of healthy subjects. The goal of the present study was to determine if the colonic barrier could be improved in tissue from subjects with ulcerative colitis (UC).

METHODS

Colonoid cultures were established with colon biopsies from 9 individuals with UC. The colonoids were then incubated for a 2-week period under control conditions (in culture medium with a final calcium concentration of 0.25 mM) or in the same medium supplemented with Aquamin® to provide 1.5 - 4.5 mM calcium. Effects on differentiation and barrier protein expression were determined using several approaches: phase-contrast and scanning electron microscopy, quantitative histology and immunohistology, mass spectrometry-based proteome assessment and transmission electron microscopy.

RESULTS

Although there were no gross changes in colonoid appearance, there was an increase in lumen diameter and wall thickness on histology and greater expression of cytokeratin 20 (CK20) along with reduced expression of Ki67 by quantitative immunohistology observed with intervention. In parallel, upregulation of several differentiation-related proteins was seen in a proteomic screen with the intervention. Aquamin®-treated colonoids demonstrated a modest up-regulation of tight junctional proteins but stronger induction of adherens junction and desmosomal proteins. Increased desmosomes were seen at the ultrastructural level. Proteomic analysis demonstrated increased expression of several basement membrane proteins and hemidesmosomal components. Proteins expressed at the apical surface (mucins and trefoils) were also increased as were several additional proteins with anti-microbial activity or that modulate inflammation. Finally, several transporter proteins that affect electrolyte balance (and, thereby affect water resorption) were increased. At the same time, growth and cell cycle regulatory proteins (Ki67, nucleophosmin, and stathmin) were significantly down-regulated. Laminin interactions, matrix formation and extracellular matrix organization were the top three up-regulated pathways with the intervention.

CONCLUSION

A majority of individuals including patients with UC do not reach the recommended daily intake for calcium and other minerals. To the extent that such deficiencies might contribute to the weakening of the colonic barrier, the findings employing UC tissue-derived colonoids here suggest that adequate mineral intake might improve the colonic barrier.

Soluble epoxide hydrolase as a therapeutic target for obesity-induced disorders: roles of gut barrier function involved

Emerging research supports that soluble epoxide hydrolase (sEH), an enzyme involved in eicosanoid metabolism, could be a promising target for obesity-associated disorders. The sEH enzyme is overexpressed in many tissues of obese animals. Genetic ablation or pharmacological inhibition of sEH attenuates the development of a wide range of obesity-induced disorders, including endoplasmic reticulum stress, metabolic syndrome, kidney diseases, insulin resistance, fatty liver, hepatic steatosis, inflammation, and endothelial dysfunction. Furthermore, our recent research showed that genetic ablation or inhibition of sEH attenuated obesity-induced intestinal barrier dysfunction and its resulted bacterial translocation, which is widely regarded to be a central mechanism for the pathogenesis of various obesity-induced disorders. Together, these results support that targeting sEH could be a promising strategy to reduce risks of obesity-induced disorders, at least in part through blocking obesity-induced leaky gut syndrome.

Idebenone Protects against Spontaneous Chronic Murine Colitis by Alleviating Endoplasmic Reticulum Stress and Inflammatory Response

Endoplasmic reticulum (ER) stress in intestinal secretory goblet cells has been linked to the development of ulcerative colitis (UC). Emerging evidence suggests that the short chain quinone drug idebenone displays anti-inflammatory activity in addition to its potent antioxidant and mitochondrial electron donor properties. This study evaluated the impact of idebenone in Winnie mice, that are characterized by spontaneous chronic intestinal inflammation and ER stress caused by a missense mutation in the mucin MUC2 gene. Idebenone (200 mg/kg) was orally administered daily to 5-6 weeks old Winnie mice over a period of 21 days. Idebenone treatment substantially improved body weight gain, disease activity index (DAI), colon length and histopathology score. Immunohistochemistry revealed increased expression of MUC2 protein in goblet cells, consistent with increased MUC2 mRNA levels. Furthermore, idebenone significantly reduced the expression of the ER stress markers C/EBP homologous protein (CHOP), activating transcription factor 6 (ATF6) and X-box binding protein-1 (XBP-1) at both mRNA and protein levels. Idebenone also effectively reduced pro-inflammatory cytokine levels in colonic explants. Taken together, these results indicate that idebenone could represent a potential therapeutic approach against human UC by its strong anti-inflammatory activity and its ability to reduce markers of ER stress.

Effects of oral bovine lactoferrin on a mouse model of inflammation associated colon cancer

Patients with ulcerative colitis or colonic Crohn's disease have a significantly increased risk of developing colorectal cancer. Bovine lactoferrin (bLF) reportedly inhibited the development of colon cancer in rats and mice, and in a placebo controlled trial, ingestion of bLF inhibited the growth of intestinal polyps. In addition, in a case study, a patient with Crohn's disease was reported to have remained in remission for over 7 years while ingesting 1 g of bLF daily. Thus, bLF has an inhibitory effect on colon carcinogenesis, and it may also promote remission of Crohn's disease. The purpose of this study was to investigate the effects of bLF in a mouse model of colorectal cancer related to irritable bowel disease (IBD). The mice were divided into 4 groups: (i) no treatment; (ii) treated with bLF only; (iii) treated with azoxymethane plus dextran sulfate sodium (AOM + DSS); and (iv) treated with AOM + DSS + bLF. AOM was used to initiate intestinal cancer, and DSS was used to induce IBD-like inflammation in the intestine of the C57BL/6 mice. At the end of the study, the mice treated with AOM + DSS + bLF had a better fecal score, fewer lesions in the colon, and less weight loss than the mice treated with AOM + DSS without bLF. However, there were no statistically significant differences between the two groups with respect to tumor burden.

p-Cymene and Rosmarinic Acid Ameliorate TNBS-Induced Intestinal Inflammation Upkeeping ZO-1 and MUC-2: Role of Antioxidant System and Immunomodulation

p-Cymene (p-C) and rosmarinic acid (RA) are secondary metabolites that are present in medicinal herbs and Mediterranean spices that have promising anti-inflammatory properties. This study aimed to evaluate their intestinal anti-inflammatory activity in the trinitrobenzene sulphonic acid (TNBS)-induced colitis model in rats. p-C and RA (25-200 mg/kg) oral administration reduced the macroscopic lesion score, ulcerative area, intestinal weight/length ratio, and diarrheal index in TNBS-treated animals. Both compounds (200 mg/kg) decreased malondialdehyde (MDA) and myeloperoxidase (MPO), restored glutathione (GSH) levels, and enhanced fluorescence intensity of superoxide dismutase (SOD). They also decreased interleukin (IL)-1β and tumor necrosis factor (TNF)-α, and maintained IL-10 basal levels. Furthermore, they modulated T cell populations (cluster of differentiation (CD)4+, CD8+, or CD3+CD4+CD25+) analyzed from the spleen, mesenteric lymph nodes, and colon samples, and also decreased cyclooxigenase 2 (COX-2), interferon (IFN)-γ, inducible nitric oxide synthase (iNOS), and nuclear transcription factor kappa B subunit p65 (NFκB-p65) mRNA transcription, but only p-C interfered in the suppressor of cytokine signaling 3 (SOCS3) expression in inflamed colons. An increase in gene expression and positive cells immunostained for mucin type 2 (MUC-2) and zonula occludens 1 (ZO-1) was observed. Altogether, these results indicate intestinal anti-inflammatory activity of p-C and RA involving the cytoprotection of the intestinal barrier, maintaining the mucus layer, and preserving communicating junctions, as well as through modulation of the antioxidant and immunomodulatory systems.

Site-specific targeted drug delivery systems for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) includes Crohn's disease and ulcerative colitis and manifests as a complex and dysregulated immune response. To date, there is no cure for IBD; thus, lifelong administration of maintenance drugs is often necessary. Since conventional IBD treatment strategies do not target the sites of inflammation, only limited efficacy is observed with their use. Moreover, the possibility of severe side effects resulting from systemic drug redistribution is high when conventional drug treatments are used. Therefore, a straightforward disease-targeted drug delivery system is desirable. Based on the pathophysiological changes associated with IBD, novel site-specific targeted drug delivery strategies that deliver drugs directly to the inflammation sites can enhance drug accumulation and decrease side effects. This review summarizes novel inflammation targeted delivery systems in the management of IBD. It also discusses the challenges and new perspectives in this field.