IL-10 promotes production of intestinal mucus by suppressing protein misfolding and endoplasmic reticulum stress in goblet cells

Mucins Dynamics in Physiological and Pathological Conditions

Maintaining intestinal health requires clear segregation between epithelial cells and luminal microbes. The intestinal mucus layer, produced by goblet cells (GCs), is a key element in maintaining the functional protection of the epithelium. The importance of the gut mucus barrier is highlighted in mice lacking Muc2, the major form of secreted mucins. These mice show closer bacterial residence to epithelial cells, develop spontaneous colitis and became moribund when infected with the attaching and effacing pathogen, Citrobacter rodentium. Furthermore, numerous observations have associated GCs and mucus layer dysfunction to the pathogenesis of inflammatory bowel disease (IBD). However, the molecular mechanisms that regulate the physiology of GCs and the mucus layer remain obscured. In this review, we consider novel findings describing divergent functionality and expression profiles of GCs subtypes within intestinal crypts. We also discuss internal (host) and external (diets and bacteria) factors that modulate different aspects of the mucus layer as well as the contribution of an altered mucus barrier to the onset of IBD.

Cross-talk of inflammatory mediators and airway epithelium reveals the cystic fibrosis transmembrane conductance regulator as a major target

Airway inflammation, mucus hyperproduction and epithelial remodelling are hallmarks of many chronic airway diseases, including asthma, COPD and cystic fibrosis. While several cytokines are dysregulated in these diseases, most studies focus on the response of airways to interleukin (IL)-4 and IL-13, which have been shown to induce mucus hyperproduction and shift the airway epithelium towards a hypersecretory phenotype. We hypothesised that other cytokines might induce the expression of chloride (Cl^-) channels/transporters, and regulate epithelial differentiation and mucus production. To this end, fully differentiated human airway basal cells (BCi-NS1.1) were treated with cytokines identified as dysregulated in those diseases, namely IL-8, IL-1β, IL-4, IL-17A, IL-10 and IL-22, and tumour necrosis factor-α. Our results show that the cystic fibrosis transmembrane conductance regulator (CFTR) is the main Cl^- channel modulated by inflammation, in contrast to transmembrane protein 16A (TMEM16A), whose levels only changed with IL-4. Furthermore, we identified novel roles for IL-10 and IL-22 by influencing epithelial differentiation towards ciliated cells and away from pulmonary ionocytes. In contrast, IL-1β and IL-4 reduced the number of ciliated cells while increasing club cells. Interestingly, while IL-1β, IL-4 and IL-10 upregulated CFTR expression, IL-4 was the only cytokine that increased both its function and the number of CFTR-expressing club cells, suggesting that this cell type may be the main contributor for CFTR function. Additionally, all cytokines assessed increased mucus production through a differential upregulation of MUC5AC and MUC5B transcript levels. This study reveals a novel insight into differentiation resulting from the cross-talk of inflammatory mediators and airway epithelial cells, which is particularly relevant for chronic airway diseases.

An accomplice more than a mere victim: The impact of β-cell ER stress on type 1 diabetes pathogenesis

BACKGROUND

Pancreatic β-cells are the insulin factory of an organism with a mission to regulate glucose homeostasis in the body. Due to their high secretory activity, β-cells rely on a functional and intact endoplasmic reticulum (ER). Perturbations to ER homeostasis and unmitigated stress lead to β-cell dysfunction and death. Type 1 diabetes (T1D) is a chronic inflammatory disease caused by the autoimmune-mediated destruction of β-cells. Although autoimmunity is an essential component of T1D pathogenesis, accumulating evidence suggests an important role of β-cell ER stress and aberrant unfolded protein response (UPR) in disease initiation and progression.

SCOPE OF REVIEW

In this article, we introduce ER stress and the UPR, review β-cell ER stress in various mouse models, evaluate its involvement in inflammation, and discuss the effects of ER stress on β-cell plasticity and demise, and islet autoimmunity in T1D. We also highlight the relationship of ER stress with other stress response pathways and provide insight into ongoing clinical studies targeting ER stress and the UPR for the prevention or treatment of T1D.

MAJOR CONCLUSIONS

Evidence from ex vivo studies, in vivo mouse models, and tissue samples from patients suggest that β-cell ER stress and a defective UPR contribute to T1D pathogenesis. Thus, restoration of β-cell ER homeostasis at various stages of disease presents a plausible therapeutic strategy for T1D. Identifying the specific functions and regulation of each UPR sensor in β-cells and uncovering the crosstalk between stressed β-cells and immune cells during T1D progression would provide a better understanding of the molecular mechanisms of disease process, and may reveal novel targets for development of effective therapies for T1D.

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.

Vagus Nerve Stimulation Protects Enterocyte Glycocalyx After Hemorrhagic Shock Via the Cholinergic Anti-Inflammatory Pathway

INTRODUCTION

Electrical vagal nerve stimulation is known to decrease gut permeability and alleviate gut injury caused by traumatic hemorrhagic shock. However, the specific mechanism of action remains unclear. Glycocalyx, located on the surface of the intestinal epithelium, is associated with the buildup of the intestinal barrier. Therefore, the goal of our study was to explore whether vagal nerve stimulation affects enterocyte glycocalyx, gut permeability, gut injury, and remote lung injury.

MATERIALS AND METHODS

Male Sprague Dawley rats were anesthetized and their cervical nerves were exposed. The rats underwent traumatic hemorrhagic shock (with maintenance of mean arterial pressure of 30-35 mmHg for 60 min) with fluid resuscitation. Vagal nerve stimulation was added to two cohorts of animals before fluid resuscitation, and one of them was injected with methyllycaconitine to block the cholinergic anti-inflammatory pathway. Intestinal epithelial glycocalyx was detected using immunofluorescence. Intestinal permeability, the degree of gut and lung injury, and inflammation factors were also assessed.

RESULTS

Vagal nerve stimulation alleviated the damage to the intestinal epithelial glycocalyx and decreased intestinal permeability by 43% compared with the shock/resuscitation phase (P < 0.05). Methyllycaconitine partly eliminated the effects of vagal nerve stimulation on the intestinal epithelial glycocalyx (P < 0.05). Vagal nerve stimulation protected against traumatic hemorrhagic shock/fluid resuscitation-induced gut and lung injury, and some inflammatory factor levels in the gut and lung tissue were downregulated after vagal nerve stimulation (P < 0.05).

CONCLUSIONS

Vagal nerve stimulation could relieve traumatic hemorrhagic shock/fluid resuscitation-induced intestinal epithelial glycocalyx damage via the cholinergic anti-inflammatory pathway.

Aloe vera mitigates dextran sulfate sodium-induced rat ulcerative colitis by potentiating colon mucus barrier

ETHNOPHARMACOLOGICAL RELEVANCE

Aloe vera (L.) Burm. f. (Aloe vera) is a medicinal herb that used in Traditional Chinese Medicine (TCM) practice for the treatment of gastrointestinal diseases such as constipation and colitis. Recent studies also reported its beneficial effect in mitigating ulcerative colitis (UC). Nevertheless, the underlying mechanisms of Aloe vera against UC remain largely unknown.

AIM OF THE STUDY

This study aimed to explore a relation between the therapeutical effects of Aloe vera in UC and colonic mucus secretion, and further investigate the underlying pathways through which Aloe vera regulates colon mucus as well as preliminarily studied the main active constitute of Aloe vera to alleviate UC.

MATERIALS AND METHODS

UPLC-MS/MS were employed to analyze the Aloe vera extract. The rat models of UC were induced by free subjected to fresh 3% dextran sulfate sodium (DSS) solution for 8 days and then accessed to tap water for 2 days. Aloe vera extract (18 mg/kg and 72 mg/kg) or 5-ASA (400 mg/kg) was administered orally from day 1-10. At the end of experiment, rats were sacrificed and the colon tissues were harvested for analysis. UC symptoms was evaluated by disease activity index (DAI), colon length and H&E staining. The Alcian blue stain were determined colon mucus layer. Myeloperoxidase (MPO) activity, mucin and inflammatory cytokines in colon tissues were determined by ELISA. The expression of related proteins on PI3K/AKT and PKC/ERK signaling pathway was analyzed by Western blot. We then evaluated the effects of three main components of Aloe vera (Aloe-emodin, aloin A and B) on mucin secretion and cytokine expression in vitro by ELISA.

RESULTS

Oral supplement with Aloe vera extract resulted in a significantly decreased DSS-induced UC symptoms, including decreased DAI, prevention of the colon length shortening, and alleviation of the pathological changes occurring in colon. The expression of colonic pro-inflammatory mediators, including IL-6, IL-1β and TNF-α were suppressed, yet the expression of IL-10 was up-regulated by Aloe vera treatment. Moreover, Aloe vera significantly up-regulated the expressions of mucin proteins (e.g., MUC2 and MUC5AC) and increased the thickness of mucus layer in the colon. Further, we revealed that Aloe vera significantly upregulated p-PKC and p-ERK expression and downregulated p-PI3K and p-AKT expression. Finally, we discovered that treat with aloin A markedly decreased IL-6 levels and increased MUC2 expression in LPS-stimulated LS174T cell.

CONCLUSION

These results support that Aloe vera improved UC by enhancing colon mucus barrier functions in addition to reducing inflammation. Moreover, aloin A might be a main active components of Aloe vera to ameliorate UC.

The Preventive Effect of Lactobacillus plantarum ZS62 on DSS-Induced IBD by Regulating Oxidative Stress and the Immune Response

In this study, we used DSS to establish an IBD mouse model to study the preventive effect of Lactobacillus plantarum (L. plantarum) ZS62 on IBD in the context of oxidative stress and the immune response. We assessed the mitigating effect of this strain on IBD mice by examining the length of and histopathological changes in the colon, determining the serum antioxidant index and the levels of inflammatory cytokines, as well as the mRNA and protein expression levels of relevant genes. The study results showed that L. plantarum ZS62 could inhibit colonic atrophy in IBD mice, reduce the degree of colonic damage, downregulate the serum levels of MDA, MPO, IL-1β, IL-6, IL-12, TNF-α, and IFN-γ and the relative mRNA and protein expression of IL-1β, IL-12, TNF-α, COX-2, iNOS, and NF-κB p65 in mouse colon tissues, and upregulate the serum levels of CAT, T-SOD, and IL-10 and the relative mRNA and protein expression of Cu/Zn SOD, Mn SOD, GSH-Px, CAT, IL-10, and IκB-α in colon tissues. In summary, L. plantarum ZS62 exhibited a good preventive effect on DSS-induced IBD by regulating oxidative stress and the immune response.

Neuro-immune-metabolism: The tripod system of homeostasis

Homeostatic regulation of cellular and molecular processes is essential for the efficient physiological functioning of body organs. It requires an intricate balance of several networks throughout the body, most notable being the nervous, immune and metabolic systems. Several studies have reported the interactions between neuro-immune, immune-metabolic and neuro-metabolic pathways. Current review aims to integrate the information and show that neuro, immune and metabolic systems form the triumvirate of homeostasis. It focuses on the cellular and molecular interactions occurring in the extremities and intestine, which are innervated by the peripheral nervous system and for the intestine in particular the enteric nervous system. While the interdependence of neuro-immune-metabolic pathways provides a fallback mechanism in case of disruption of homeostasis, in chronic pathologies of continued disequilibrium, the collapse of one system spreads to the other interacting networks as well. Current review illustrates this domino-effect using diabetes as the main example. Together, this review attempts to provide a holistic picture of the integrated network of neuro-immune-metabolism and attempts to broaden the outlook when devising a scientific study or a treatment strategy.

Morchella importuna Flavones Improve Intestinal Integrity in Dextran Sulfate Sodium-Challenged Mice

Morchella importuna, as an edible fungus, has various health benefits. However, the effects of M. importuna on intestinal health are rarely investigated. Hence, this study aims to ascertain the influences of flavones from the fruiting bodies of M. importuna (hereinafter abbreviated as MIF) on dextran sulfate sodium (DSS)-induced damage to intestinal epithelial barrier in C57BL/6J mice. In this (14-day) study, 144 C57BL/6J mice were divided into four groups: (1) Control; (2) DSS treatment; (3) DSS treatment + 100 mg/kg MIF (LMIF); (4) DSS treatment + 200 mg/kg MIF (HMIF). On days 8-14, mice in the challenged groups were challenged with 3.5% DSS, while the control group received an equal volume of normal saline. Then, serum and intestinal samples were obtained from all mice. The results showed that MIF ingestion enhanced intestinal integrity in DSS-challenged mice, as evinced by the elevated (p < 0.05) abundances of occludin, claudin-1, and zonula occludens-1 proteins. Meanwhile, MIF ingestion reduced (p < 0.05) the colonic interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) concentrations and increased the superoxide dismutase and catalase activities and Shannon and Simpson indices in DSS-challenged mice. Moreover, MIF ingestion reduced (p < 0.05) the abundance of phospho-nuclear factor (NF)-κB and increased the abundance of phospho-Nrf2 in DSS-challenged mice. Taken together, MIF protects against intestinal barrier injury in C57BL/6J mice via a mechanism that involves inhibiting NF-κB activation and promoting Nrf2 activation, as well as regulating intestinal microbiota.

Gut Microbiota and Dietary Factors as Modulators of the Mucus Layer in Inflammatory Bowel Disease

The gastrointestinal tract is optimized to efficiently absorb nutrients and provide a competent barrier against a variety of lumen environmental compounds. Different regulatory mechanisms jointly collaborate to maintain intestinal homeostasis, but alterations in these mechanisms lead to a dysfunctional gastrointestinal barrier and are associated to several inflammatory conditions usually found in chronic pathologies such as inflammatory bowel disease (IBD). The gastrointestinal mucus, mostly composed of mucin glycoproteins, covers the epithelium and plays an essential role in digestive and barrier functions. However, its regulation is very dynamic and is still poorly understood. This review presents some aspects concerning the role of mucus in gut health and its alterations in IBD. In addition, the impact of gut microbiota and dietary compounds as environmental factors modulating the mucus layer is addressed. To date, studies have evidenced the impact of the three-way interplay between the microbiome, diet and the mucus layer on the gut barrier, host immune system and IBD. This review emphasizes the need to address current limitations on this topic, especially regarding the design of robust human trials and highlights the potential interest of improving our understanding of the regulation of the intestinal mucus barrier in IBD.

Effects induced by polyethylene microplastics oral exposure on colon mucin release, inflammation, gut microflora composition and metabolism in mice

Microplastics are plastic fragments widely distributed in the environment and accumulate in the organisms. However, the research on microplastics effects in mammals is limited. Polyethylene is the main kind of microplastics in the environment. We hypothesized that polyethylene exposure disrupts host intestine metabolism by modifying intestine microflora composition and then lipopolysaccharide (LPS) pathway. Female mice were orally exposed to 0, 0.002 and 0.2 μg/g/d polyethylene microplastics (PE MPs) for 30 days. Colon mucin density was quantized after AB-PAS staining. Mucin 2 (MUC2), inflammatory factors (IL-1β, IL-6, IL-8 and IL-10), short-chain fatty acid receptors (GPR41 and GPR43), LPS receptors (TLR4 and MyD88) and LPS pathway downstream genes (ERK1 and NF-κB) mRNA levels in colon were measured. Feces were collected on the 15th day of exposure for gut microflora analysis. Blood biochemical analysis was performed. Results showed that 0.2 μg/g/d PE MPs exposure significantly decreased colon mucin expression (p < 0.05), decreased IL-1β (p < 0.05) and increased IL-8 and IL-10 levels (p < 0.01 and p < 0.001 respectively). Microflora data showed that in 0.2 μg/g/d PE MPs group the number of Firmicutes decreased and the number of Bacteroides increased (both p < 0.01). Predicted KEGG metabolic pathways by piecrust method indicated that PE MPs enhanced amino acids metabolism in microflora. ERK1 and NF-κB mRNA were significantly lower in 0.2 μg/g/d PE MPs group (both p < 0.001). Blood total protein, albumin and globulin levels significantly increased after 0.2 μg/g/d PE MPs exposure (p < 0.01, p < 0.01 and p < 0.05 respectively). These results indicate that PE MPs exposure induced decreased mucin production, a slight immune response and increased the microflora amino acid metabolism in the mice colon by modifying colon microflora composition. SUMMARY: Polyethylene microplastics exposure decreased colon mucin release and increased amino acid metabolism by modifying colon microflora composition.

Effect of Dietary Clostridium butyricum Supplementation on Growth Performance, Intestinal Barrier Function, Immune Function, and Microbiota Diversity of Pekin Ducks

Simple Summary

In poultry farming, the use of prophylactic antibiotics can lead to increased resistance, so probiotics are a good alternative. Clostridium butyricum (C. butyricum) has been widely used to improve the gut health of animals. Therefore, we carried out the current study of Pekin ducks supplemented with C. butyricum for a period of 42 days. Here, we found a clear increase in the growth performance of Pekin ducks supplemented with C. butyricum. Moreover, a high level of secretory IgA, IgM, IgG, IL-4, and IL-10 and comparatively higher short-chain fatty acids (SCFAs) and intestinal tight junction changes were found in Pekin ducks supplemented with C. butyricum. The gut microbial diversity of Pekin ducks supplemented with C. butyricum was clearly different than that of Pekin ducks fed a non-C. butyricum diet. In conclusion, our findings suggest that 400 mg/kg C. butyricum supplementation improved the intestinal health of Pekin ducks by increasing the α-diversity of intestinal microbiota, enhancing the SCFAs contents, and strengthening the intestinal barrier function and immune systems indicating that 400 mg/kg C. butyricum might be a preferable antibiotic alternative for commercial application.

Abstract

Clostridium butyricum (C. butyricum) is increasingly being used to test the promotion of the gut health of animals. However, the modes of action for such applications for waterfowl remain unclear. Thus, we investigated whether or not intestinal barrier function, immune-related gene expression, and the diversity of the intestinal microbiota in Pekin ducks varied under C. butyricum supplementation. A total of 500 ducks were randomly assigned into five treatments supplemented with basal diets containing: either 0 (group Control), 200 (group CB200), 400 (group CB400) and 600 (group CB600) mg/kg C. butyricum or 150 mg/kg aureomycin (group A150) for 42 days. In comparison with the control group, C. butyricum supplementation enhanced the growth performance and intestinal villus height of Pekin ducks at 42 d. Serum immune indexes and fecal short-chain fatty acids (SCFAs) were all improved at both 21 d and 42 d after C. butyricum addition. The mRNA expression levels of Mucin2, Zonula occludens-1 (ZO-1), Caudin-3, and Occludin increased at 21 d and 42 d and the mRNA expression levels of IL-4 and IL-10 only increased at 42 d after C. butyricum addition. Dietary C. butyricum also resulted in an increase in the number of diversities of operational taxonomic units (OTUs), and an increase in the α-diversity of intestinal microbiota. The addition of C. butyricum altered the composition of the intestinal microbiota from 21 d to 42 d. The relative abundance of Firmicutes and Bacteroidetes showed little changes among groups; however, the relative abundance of Firmicutes/Bacteroidetes were found to have been significantly different between the 21 d and 42 d. C. butyricum administration improved the intestinal health of Pekin ducks by increasing the diversity of intestinal microbiota, enhancing the SCFAs contents, and strengthening the intestinal barrier function and immune systems. The optimal dietary supplementation dosage was recommended as 400 mg/kg in the diet.

Early-Released Interleukin-10 Significantly Inhibits Lipopolysaccharide-Elicited Neuroinflammation In Vitro

Anti-inflammatory cytokine interleukin (IL)-10 is pivotal for limiting excessive inflammation in the central nervous system. Reports show that lipopolysaccharide (LPS)-induced microglial IL-10 emerges in a delayed manner in vitro and in vivo, lagging behind proinflammatory cytokines to facilitate the resolution of neuroinflammation. We hypothesized that IL-10 releases quite quickly based on our pilot investigation. Here, we uncovered a bimodal expression of microglial IL-10 gene transcription induced by LPS in mouse primary mixed glial cultures. This pattern consisted of a short brief early-phase and a long-lived late-phase, enabling the production of IL-10 protein in a rapid manner. The removal and addition of IL-10 protein assays indicated that early-released IL-10 exerted potent modulatory effects on neuroinflammation at picomolar levels, and IL-10 released at the onset of neuroinflammation is tightly controlled. We further showed that the early-released, but not the late-released, IL-10 was crucial for mediating and potentiating the anti-inflammatory function of a β2-adrenergic receptor agonist salmeterol. This study in vitro highlights the essential role of early-released IL-10 in regulating the appropriate degree of neuroinflammation, overturning the previous notion that microglial IL-10 produces and functions in a delayed manner and providing new insights into anti-inflammatory mechanisms-mediated neuroimmune homeostasis.

The Production and Function of Endogenous Interleukin-10 in Intestinal Epithelial Cells and Gut Homeostasis

The healthy gut is achieved and maintained through a balanced relationship between the mucosal immune system, microbial communities resident in the lumen, and the intestinal epithelium. The intestinal epithelium plays an exceptionally important role in harmonizing the interaction between the host immunity and the luminal residents, as this selectively permeable barrier separates but also allows interchange between the 2 environments. Interleukin (IL)-10 has been well established to play an important role in maintaining gut homeostasis by imparting diverse effects on a variety of cell types in this relationship. In the intestine, the source and the target of IL-10 include leukocytes and epithelial cells. Given that both the epithelium and IL-10 are essential players in supporting homeostasis, we discuss the relationship between these 2 factors, focusing on epithelial sources of IL-10 and the effects of IL-10 on the intestinal epithelium. Insight into this relationship reveals an important aspect of the innate immune function of intestinal epithelial cells.

Role of Goblet Cells in Intestinal Barrier and Mucosal Immunity

Goblet cells and the mucus they secrete serve as an important barrier, preventing pathogens from invading the mucosa to cause intestinal inflammation. The perspective regarding goblet cells and mucus has changed, with current evidence suggesting that they are not passive but play a positive role in maintaining intestinal tract immunity and mucosal homeostasis. Goblet cells could obtain luminal antigens, presenting them to the underlying antigen-presenting cells (APCs) that induces adaptive immune responses. Various immunomodulatory factors can promote the differentiation and maturation of goblet cells, and the secretion of mucin. The abnormal proliferation and differentiation of goblet cells, as well as the deficiency synthesis and secretion of mucins, result in intestinal mucosal barrier dysfunction. This review provides an extensive outline of the signaling pathways that regulate goblet cell proliferation and differentiation and control mucins synthesis and secretion to elucidate how altering these pathways affects goblet functionality. Furthermore, the interaction between mucins and goblet cells in intestinal mucosal immunology is described. Therefore, the contribution of goblet cells and mucus in promoting gut defense and homeostasis is illustrated, while clarifying the regulatory mechanisms involved may allow the development of new therapeutic strategies for intestinal disorders.

Consequence of distinctive expression of MUC2 in colorectal cancers: How much is actually bad?

Colorectal cancer (CRC) exhibits complex pathogenesis via compromised intestinal mucosal barrier. It is accepted that goblet cells secrete mucin which line the intestinal mucosal barrier and offer wide range protection and maintain the gut integrity. The principal mucin in the small and large intestine which is Mucin2 (MUC2) is predominantly expressed in the goblet cells which play a pivotal role in intestinal homeostasis. Its disruption is associated with diverse diseases and carcinomas. MUC2 has lately been identified as a principal marker in various mechanisms and secretory cell lineage. While MUC2 expression is regulated by various modulators, alterations in its expression are associated with immunomodulation, differences in tumor immunity and also regulation of microbiota. In the light of current literature, the present review explicates the regulation, functional mechanisms and essential role of MUC2 in colorectal cancer and aids in providing deep understanding of pathogenesis of the disease and also specifies the importance of the MUC2 in gaining more insights about the subtypes of colorectal cancer and how it can succour in approximating the prognosis and survival of the patients.

Interleukin-33 alleviates diabetic cardiomyopathy through regulation of endoplasmic reticulum stress and autophagy via insulin-like growth factor-binding protein 3

Prolonged endoplasmic reticulum (ER) stress is the key driving force behind diabetic cardiomyopathy (DCM). Autophagy is extensively implicated in adaptive mechanisms for cell survival. Interleukin-33 (IL-33) is known to be a potent cardiac protector, but its roles in DCM, ER stress, and autophagy are currently unknown. We aimed to explore the effects of IL-33 on DCM and characterize the roles that ER stress and autophagy play in DCM. The effects of IL-33 on DCM, ER stress, and autophagy were characterized both in db/db mice and in palmitic acid (PA)-treated cardiomyocytes. The manipulators of ER stress and autophagy were used to clarify their roles in DCM remittance conferred by IL-33. Gene expression analysis was used to identify IL-33-dependent regulators of ER stress and autophagy. Both db/db mice and PA-treated cells presented with enhanced levels of ER stress, apoptosis, and lipid deposition, as well as impaired autophagy, all of which could be reversed by IL-33. Treatment with IL-33 improved the cardiac diastolic function of diabetic mice. Nonselective autophagy inhibitors, such as 3-methyladenine (3-MA) or wortmannin, abolished the protective effects of IL-33, resulting in an increase in both ER stress and apoptosis. Strikingly, insulin-like growth factor-binding protein 3 (IGFBP3) was identified as the gene most significantly differentially expressed between IL-33 and control groups. Knockdown of IGFBP3 expression, similar to the effect of nonselective autophagy inhibitors, resulted in high levels of ER stress, impaired autophagy, and apoptosis that were not rescued upon treatment with IL-33. IL-33 abates DCM by alleviating ER stress and promoting autophagy. IGFBP3 is essential for IL-33-induced ER stress resolution and autophagic enhancement during DCM.

Fermented Rice Bran Supplementation Prevents the Development of Intestinal Fibrosis Due to DSS-Induced Inflammation in Mice

Fermented rice bran (FRB) is known to protect mice intestines against dextran sodium sulfate (DSS)-induced inflammation; however, the restoration of post-colitis intestinal homeostasis using FRB supplementation is currently undocumented. In this study, we observed the effects of dietary FRB supplementation on intestinal restoration and the development of fibrosis after DSS-induced colitis. DSS (1.5%) was introduced in the drinking water of mice for 5 days. Eight mice were sacrificed immediately after the DSS treatment ended. The remaining mice were divided into three groups, comprising the following diets: control, 10% rice bran (RB), and 10% FRB-supplemented. Diet treatment was continued for 2 weeks, after which half the population of mice from each group was sacrificed. The experiment was continued for another 3 weeks before the remaining mice were sacrificed. FRB supplementation could reduce the general observation of colitis and production of intestinal pro-inflammatory cytokines. FRB also increased intestinal mRNA levels of anti-inflammatory cytokine, tight junction, and anti-microbial proteins. Furthermore, FRB supplementation suppressed markers of intestinal fibrosis. This effect might have been achieved via the canonical Smad2/3 activation and the non-canonical pathway of Tgf-β activity. These results suggest that FRB may be an alternative therapeutic agent against inflammation-induced intestinal fibrosis.

Emerging concepts in intestinal immune control of obesity-related metabolic disease

The intestinal immune system is an important modulator of glucose homeostasis and obesity-associated insulin resistance. Dietary factors, the intestinal microbiota and their metabolites shape intestinal immunity during obesity. The intestinal immune system in turn affects processes such as intestinal permeability, immune cell trafficking, and intestinal hormone availability, impacting systemic insulin resistance. Understanding these pathways might identify mechanisms underlying treatments for insulin resistance, such as metformin and bariatric surgery, or aid in developing new therapies and vaccination approaches. Here, we highlight evolving concepts centered on intestinal immunity, diet, and the microbiota to provide a working model of obesity-related metabolic disease.

ALG3 contributes to stemness and radioresistance through regulating glycosylation of TGF-β receptor II in breast cancer

Background

Radiotherapy is a conventional and effective local treatment for breast cancer. However, residual or recurrent tumors appears frequently because of radioresistance. Novel predictive marker and the potential therapeutic targets of breast cancer radioresistance needs to be investigated.

Methods

In this study, we screened all 10 asparagine-linked glycosylation (ALG) members in breast cancer patients’ samples by RT-PCR. Cell viability after irradiation (IR) was determined by CCK-8 assay and flow cytometry. The radiosensitivity of cell lines with different ALG3 expression was determined with the colony formation assay by fitting the multi-target single hit model to the surviving fractions. Cancer stem-like traits were assessed by RT-PCR, Western blot, and flow cytometry. The mechanisms of ALG3 influencing radiosensitivity was detected by Western blot and immunoprecipitation. And the effect of ALG3 on tumor growth after IR was verified in an orthotopic xenograft tumor models. The association of ALG3 with prognosis of breast cancer patients was confirmed by immunohistochemistry.

Results

ALG3 was the most significantly overexpressing gene among ALG family in radioresistant breast cancer tissue. Overexpression of ALG3 predicted poor clinicopathological characteristics and overall survival (OS), and early local recurrence-free survival (LRFS) in breast cancer patients. Upregulating ALG3 enhanced radioresistance and cancer stemness in vitro and in vivo. Conversely, silencing ALG3 increased the radiosensitivity and repressed cancer stemness in vitro, and more importantly inhibition of ALG3 effectively increased the radiosensitivity of breast cancer cells in vivo. Mechanistically, our results further revealed ALG3 promoted radioresistance and cancer stemness by inducing glycosylation of TGF-β receptor II (TGFBR2). Importantly, both attenuation of glycosylation using tunicamycin and inhibition of TGFBR2 using LY2109761 differentially abrogated the stimulatory effect of ALG3 overexpression on cancer stemness and radioresistance. Finally, our findings showed that radiation played an important role in preventing early recurrence in breast cancer patients with low ALG3 levels, but it had limited efficacy in ALG3-overexpressing breast cancer patients.

Conclusion

Our results suggest that ALG3 may serve as a potential radiosensitive marker, and an effective target to decrease radioresistance by regulating glycosylation of TGFBR2 in breast cancer. For patients with low ALG3 levels, radiation remains an effective mainstay therapy to prevent early recurrence in breast cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01932-8.

S-methyl cysteine sulfoxide ameliorates duodenal morphological alterations in streptozotocin-induced diabetic rats

Diabetes mellitus (DM) is a metabolic disease associated with several intestinal disorders. S-methyl cysteine sulfoxide (SMCS) ​​is an amino acid present in Allium cepa L with hypoglycemic effects. However, the effects of SMCS on diabetic intestinal changes are unknown. Thus, we aimed to investigate the effects of SMCS on duodenal morphology and immunomodulatory markers in diabetic rats. Twenty-six rats were divided into three groups: control (C), diabetic (D) and diabetic +200 mg/kg SMCS (DSM). DM was induced by intraperitoneal injection of streptozotocin (50 mg/kg). After 30 days, duodenum samples were processed to assess histopathological and stereological alterations in volume, villus length, and immunohistochemical expression of NF-kB, IL-10, BCL-2, and caspase-3. SMCS reduced hyperglycemia and mitigated the increase in total reference volume of the duodenum, the absolute volume of the mucosa, and the length of the intestinal crypts in the DMS group when compared to D. IL-10 immunostaining was reduced in D when compared to C, while NF-kB was increased in D in comparison to the other groups. SMCS ​​supplementation could decrease the NF-kB immunostaining observed in D. Positive staining for BCL-2 and caspase-3 were not statistically different between groups. In summary, SMCS decreased hyperglycemia and mitigated the morphological changes of the duodenum in diabetic animals, and these beneficial effects can be partially explained by NF-kB modulation.

Regulation of Intestinal Stem Cell Stemness by the Aryl Hydrocarbon Receptor and Its Ligands

Maintenance of intestinal homeostasis requires the integration of immunological and molecular processes together with environmental, diet, metabolic and microbial cues. Key to this homeostasis is the proper functioning of epithelial cells originating from intestinal stem cells (ISCs). While local factors and numerous molecular pathways govern the ISC niche, the conduit through which these processes work in concordance is the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, whose role in immunoregulation is critical at barrier surfaces. In this review, we discuss how AhR signaling is emerging as one of the critical regulators of molecular pathways involved in epithelial cell renewal. In addition, we examine the putative contribution of specific AhR ligands to ISC stemness and epithelial cell fate.

The Inhibitory Effect of Artesunate on Excessive Endoplasmic Reticulum Stress Alleviates Experimental Colitis in Mice

Endoplasmic reticulum (ER) stress may contribute to the pathogenesis and perpetuation of ulcerative colitis (UC). Previous studies have shown artesuante (ARS) has the protective effect on experimental UC. Therefore, it can be assumed that ARS can regulate ER stress and its related reactions. Dextran sulfate sodium (DSS) induced UC model in mice was used to testify this hypothesis. The results clearly showed that DSS exposure caused excessive ER stress evidenced by a markedly increase of GRP78 and CHOP expression, and then activated the ER stress sensors PERK, IRE1, ATF6 and their respective signaling pathways, followed by upregulated caspases12 and lowered Bcl-2/Bax ratio. However, ARS treatment significantly inhibited the occurrence of ER stress via preventing the activation of PERK-eIF2α-ATF4-CHOP and IRE1α-XBP1 signaling pathways, concurrently ER-stress-associated apoptosis in colon tissues. Moreover, ARS treatment remarkably inhibited the activation of NF-κB and the expression levels of pro-inflammatory cytokines, improved the clinical and histopathological alterations as well as maintained the expression of claudin-1 and Muc2 in mucosal layer of colon. Notably, the classic ER stress inhibitor 4-phenyhlbutyric acid enhanced the beneficial effects of ARS; in contrast, the ER stress inducer 2-deoxy-d-glucose substantially abrogated the above-mentioned effects, uncovering the involvement of ER stress in the response. These findings indicated the protection of ARS on UC is associated with its suppressing excessive ER stress mediated intestinal barrier damage and inflammatory response. This study provides a novel aspect to understand the mechanism of ARS against UC.

Metabolomics as a Promising Resource Identifying Potential Biomarkers for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a relapsing chronic disorder of the gastrointestinal tract characterized by disruption of epithelial barrier function and excessive immune response to gut microbiota. The lack of biomarkers providing early diagnosis or defining the status of the pathology difficulties an accurate assessment of the disease. Given the different metabolomic profiles observed in IBD patients, metabolomics may reveal prime candidates to be studied, which may help in understanding the pathology and identifying novel therapeutic targets. In this review, we summarize the most current advances describing the promising metabolites such as lipids or amino acids found through untargeted metabolomics from serum, faecal, urine and biopsy samples.

Regulation of Intestinal Inflammation by Dietary Fats

With the epidemic of human obesity, dietary fats have increasingly become a focal point of biomedical research. Epidemiological studies indicate that high-fat diets (HFDs), especially those rich in long-chain saturated fatty acids (e.g., Western Diet, National Health Examination survey; NHANES 'What We Eat in America' report) have multi-organ pro-inflammatory effects. Experimental studies have confirmed some of these disease associations, and have begun to elaborate mechanisms of disease induction. However, many of the observed effects from epidemiological studies appear to be an over-simplification of the mechanistic complexity that depends on dynamic interactions between the host, the particular fatty acid, and the rather personalized genetics and variability of the gut microbiota. Of interest, experimental studies have shown that certain saturated fats (e.g., lauric and myristic fatty acid-rich coconut oil) could exert the opposite effect; that is, desirable anti-inflammatory and protective mechanisms promoting gut health by unanticipated pathways. Owing to the experimental advantages of laboratory animals for the study of mechanisms under well-controlled dietary settings, we focus this review on the current understanding of how dietary fatty acids impact intestinal biology. We center this discussion on studies from mice and rats, with validation in cell culture systems or human studies. We provide a scoping overview of the most studied diseases mechanisms associated with the induction or prevention of Inflammatory Bowel Disease in rodent models relevant to Crohn's Disease and Ulcerative Colitis after feeding either high-fat diet (HFD) or feed containing specific fatty acid or other target dietary molecule. Finally, we provide a general outlook on areas that have been largely or scarcely studied, and assess the effects of HFDs on acute and chronic forms of intestinal inflammation.

Receptor-targeted engineered probiotics mitigate lethal Listeria infection

Probiotic bacteria reduce the intestinal colonization of pathogens. Yet, their use in preventing fatal infection caused by foodborne Listeria monocytogenes (Lm), is inconsistent. Here, we bioengineered Lactobacillus probiotics (BLP) to express the Listeria adhesion protein (LAP) from a non-pathogenic Listeria (L. innocua) and a pathogenic Listeria (Lm) on the surface of Lactobacillus casei. The BLP strains colonize the intestine, reduce Lm mucosal colonization and systemic dissemination, and protect mice from lethal infection. The BLP competitively excludes Lm by occupying the surface presented LAP receptor, heat shock protein 60 and ameliorates the Lm-induced intestinal barrier dysfunction by blocking the nuclear factor-κB and myosin light chain kinase-mediated redistribution of the major epithelial junctional proteins. Additionally, the BLP increases intestinal immunomodulatory functions by recruiting FOXP3+T cells, CD11c+ dendritic cells and natural killer cells. Engineering a probiotic strain with an adhesion protein from a non-pathogenic bacterium provides a new paradigm to exclude pathogens and amplify their inherent health benefits.

Bifidobacterium adolescentis supplementation attenuates fracture-induced systemic sequelae

The gut microbiota is an important contributor to both health and disease. While previous studies have reported on the beneficial influences of the gut microbiota and probiotic supplementation on bone health, their role in recovery from skeletal injury and resultant systemic sequelae remains unexplored. This study aimed to determine the extent to which probiotics could modulate bone repair by dampening fracture-induced systemic inflammation. Our findings demonstrate that femur fracture induced an increase in gut permeability lasting up to 7 days after trauma before returning to basal levels. Strikingly, dietary supplementation with Bifidobacterium adolescentis augmented the tightening of the intestinal barrier, dampened the systemic inflammatory response to fracture, accelerated fracture callus cartilage remodeling, and elicited enhanced protection of the intact skeleton following fracture. Together, these data outline a mechanism whereby dietary supplementation with beneficial bacteria can be therapeutically targeted to prevent the systemic pathologies induced by femur fracture.

Cancer-protective effect of a synbiotic combination between Lactobacillus gasseri 505 and a Cudrania tricuspidata leaf extract on colitis-associated colorectal cancer

Previously, a synbiotic combination of probiotic Lactobacillus gasseri 505 (LG) and a new prebiotic, Cudrania tricuspidata leaf extract (CT) in fermented milk, designated FCT, showed an in vitro immunomodulatory effect and antioxidant activity. Although synbiotic combination might have cancer-protective effects, these activities have not been fully validated in vivo. Ten-week treatment of LG, CT, or FCT to azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis-associated colorectal cancer (CAC) mouse model reduced both the incidence of colonic tumors and damage to the colonic mucosa effectively, suggesting a cancer-protective effect. To understand these, biomarkers associated with inflammation, colon barrier, apoptosis, and cancer cell proliferation were monitored in AOM/DSS group versus LG/CT/FCT groups. A synbiotic combination (FCT) down-regulated pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1β, and IL-6) and inflammation-associated enzymes (iNOS and COX-2), and up-regulated anti-inflammatory cytokines (IL-4 and IL-10). In addition, colon barrier experiment revealed that biomarkers of mucus layer (MUC-2 and TFF3) and tight junction (occludin and ZO-1) were up-regulated. Subsequent apoptosis experiment showed that pro-apoptotic factors (p53, p21, and Bax) were up-regulated and anti-apoptotic factors (Bcl-2 and Bcl-xL) were down-regulated. Furthermore, comparative metagenome analysis of gut microbiota revealed that Staphylococcus decreased but Lactobacillus, Bifidobacterium, and Akkermansia increased, supporting their protective effects, accompanied by increased short-chain fatty acids (SCFAs). Taken together, the FCT administration showed cancer-protective effects by reducing the risk of colitis-associated colon cancer via regulation of inflammation, carcinogenesis, and compositional change of gut microbiota. Consequently, the synbiotic combination (FCT) could be a novel potential health-protective natural agent against CAC.

An IL-27-Driven Transcriptional Network Identifies Regulators of IL-10 Expression across T Helper Cell Subsets

Interleukin-27 (IL-27) is an immunoregulatory cytokine that suppresses inflammation through multiple mechanisms, including induction of IL-10, but the transcriptional network mediating its diverse functions remains unclear. Combining temporal RNA profiling with computational algorithms, we predict 79 transcription factors induced by IL-27 in T cells. We validate 11 known and discover 5 positive (Cebpb, Fosl2, Tbx21, Hlx, and Atf3) and 2 negative (Irf9 and Irf8) Il10 regulators, generating an experimentally refined regulatory network for Il10. We report two central regulators, Prdm1 and Maf, that cooperatively drive the expression of signature genes induced by IL-27 in type 1 regulatory T cells, mediate IL-10 expression in all T helper cells, and determine the regulatory phenotype of colonic Foxp3⁺ regulatory T cells. Prdm1/Maf double-knockout mice develop spontaneous colitis, phenocopying ll10-deficient mice. Our work provides insights into IL-27-driven transcriptional networks and identifies two shared Il10 regulators that orchestrate immunoregulatory programs across T helper cell subsets.

Zhang et al. construct a transcriptional network for IL-27-mediated Il10 production in CD4 T cells, characterize the function of 16 Il10 regulators, and uncover the role of two transcription factors, Prdm1 and Maf, in driving Il10 production in all T helper cells and in maintaining immune homeostasis in the colon.

The relationship between intestinal goblet cells and the immune response

Goblet cells (GCs) are single-cell glands that produce and secrete mucin. Mucin forms a mucus layer, which can separate the materials in cavities from the intestinal epithelium and prevent the invasion of pathogenic microorganisms in various ways. GCs can also participate in the immune response through nonspecific endocytosis and goblet cell-associated antigen passages (GAPs). GCs endocytose soluble substances from the lumen and transmit antigens to the underlying antigen-presenting cells (APCs). A variety of immuno-regulatory factors can promote the differentiation, maturation of GCs, and the secretion of mucin. The mucin secreted by GCs forms a mucus layer, which plays an important role in resisting the invasion of foreign bacteria and intestinal inherent microorganisms, regulating the immune performance of the body. Therefore, the present study mainly reviews the barrier function of the mucus layer, the mucus secreted by goblet cells, the protective effect against pathogenic bacteria, the delivery of luminal substances through GAPs and the relationship between GCs and the immune response.

The Many Functions of Foxp3+ Regulatory T Cells in the Intestine

Throughout the last years, gut-resident Foxp3⁺ regulatory T (Treg) cells have been associated with a growing number of tissue-specific functions in the intestine, comprising various aspects of gut immunity and physiology. Treg cells have pivotal roles in intestinal tolerance induction and host defense by actively controlling immune responses towards harmless dietary antigens and commensal microorganisms as well as towards invading pathogens. In addition to these immune-related roles, it has become increasingly clear that intestinal Treg cells also exert important non-immune functions in the gut, such as promoting local tissue repair and preserving the integrity of the epithelial barrier. Thereby, intestinal Treg cells critically contribute to the maintenance of tissue homeostasis. In order to account for this functional diversity, gut-resident Treg cells have specifically adapted to the intestinal tissue microenvironment. In this Review, we discuss the specialization of Treg cells in the intestine. We survey the different populations of gut-resident Treg cells focussing on their unique functions, phenotypes and distinct transcription factor dependencies.

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 different doses lipopolysaccharides on the mucosal barrier in mouse intestine

Lipopolysaccharide (LPS), an important component in the outer membrane of the cell wall of Gram-negative bacteria, can induce a systemic inflammatory response and play an important role in bacterial infection and disease evolution. The thick layer of mucus covering the small intestinal villus acts primarily to the first barrier from damage by toxic substances. We aimed to study the effects of LPS on the intestinal mucus layer barrier. The results showed that the thickness of the mucus layer was significantly increased by a low dose of LPS. Further, LPS can cross this barrier into the blood, put the body in a state of chronic low-grade inflammation, and activate the body's immune response. However, after a long-term high dose of LPS exposure, a large number of lysosomes in goblet cells caused a loss of function, and mucus layer thickness was significantly decreased. A large amount of LPS stuck to the mucus, leading to normal LPS and inflammatory cytokines level of plasma. The intestinal tissue morphology was damaged, and many immune cells died through necrosis in the intestine. Collectively, the function of the goblet cell was normal, a low dose of LPS cannot be stuck to the mucus layer. However, a high dose of LPS stuck to the mucus when goblet cells caused a loss of function, which can be directly linked to the severity of the immunosuppression in the body.

Mucins in Intestinal Mucosal Defense and Inflammation: Learning From Clinical and Experimental Studies

Throughout the gastrointestinal (GI) tract, a distinct mucus layer composed of highly glycosylated proteins called mucins plays an essential role in providing lubrication for the passage of food, participating in cell signaling pathways and protecting the host epithelium from commensal microorganisms and invading pathogens, as well as toxins and other environmental irritants. These mucins can be broadly classified into either secreted gel-forming mucins, those that provide the structural backbone for the mucus barrier, or transmembrane mucins, those that form the glycocalyx layer covering the underlying epithelial cells. Goblet cells dispersed among the intestinal epithelial cells are chiefly responsible for the synthesis and secretion of mucins within the gut and are heavily influenced by interactions with the immune system. Evidence from both clinical and animal studies have indicated that several GI conditions, including inflammatory bowel disease (IBD), colorectal cancer, and numerous enteric infections are accompanied by considerable changes in mucin quality and quantity. These changes include, but are not limited to, impaired goblet cell function, synthesis dysregulation, and altered post-translational modifications. The current review aims to highlight the structural and functional features as well as the production and immunological regulation of mucins and the impact these key elements have within the context of barrier function and host defense in intestinal inflammation.

Oral Delivery of β-Lactoglobulin-Nanosphere-Encapsulated Resveratrol Alleviates Inflammation in Winnie Mice with Spontaneous Ulcerative Colitis

Resveratrol (RES) is a nutraceutical with promising anti-inflammatory properties for the treatment of inflammatory bowel diseases (IBD). However, the clinical effectiveness of resveratrol as an oral anti-inflammatory agent is hindered by its extremely poor solubility and poor stability. In this study, we encapsulated resveratrol in β-lactoglobulin (BLG) nanospheres and systematically analyzed their formulation parameters in vitro followed by a thorough in vivo anti-inflammatory testing in a highly specialized spontaneous murine UC model (Winnie mice model). Complexation of resveratrol with BLG increased the aqueous solubility of resveratrol by ≈1.7 times with 10% w/w loading. Additionally, the in vitro dissolution of resveratrol from the particles was found to be higher compared to resveratrol alone, resulting in >90% resveratrol dissolution in ∼8 h. The anti-inflammatory activity of resveratrol was examined for the first time in Winnie mice, a mouse model that closely represents the clinical signs of IBD. At a 50 mg/kg oral dose for 2 weeks, BLG-RES significantly improved both % body weight and disease activity index (DAI), compared to free resveratrol in Winnie mice. Importantly, histological evaluations revealed a similar trend with striking improvement in the pathology of the colon via an increase in goblet cell numbers and recovery of colonic epithelium. BLG-RES significantly increased the expression level of cytokine interleukin-10 (Il10), which confirms the reduction in inflammation potentially because of the increased dissolution and stability of resveratrol by complexation with BLG. This comprehensive study demonstrates the effectiveness of biocompatible nanomaterials such as BLG in oral delivery of poorly soluble anti-inflammatory molecules such as resveratrol in the treatment of IBD.

Plasma cytokine levels in patients with chronic alcohol overconsumption: Relations to gut microbiota markers and clinical correlates

BACKGROUND

Alcohol-related morbidity may involve changes in the gut microbiota and immune dysregulation. We have previously demonstrated alterations in gut microbiota composition and functions in patients with alcohol overconsumption, and now aimed to investigate possible associations between cytokine levels, gut microbiota, and clinical symptoms.

METHODS

We included hospital inpatients with a history of chronic alcohol overconsumption. For comparison, we included control patients with a low alcohol intake. Cytokine levels (TGF-β1, TNF-α, IL-10, IL-8, IL-6, IFN-γ, MCP-1, IL-1RA, IL-1β, and IL-17) were determined using a customized V-plex assay. We then examined associations of cytokine levels with the abundance of Proteobacteria and Faecalibacterium, percentage of the short-chain fatty acid butyrate, psychiatric symptoms (Hospital Anxiety and Depression Scale), and biochemical liver variables.

RESULTS

We included 28 patients with alcohol overconsumption (79% men), and 25 control patients (72% men). Patients with alcohol overconsumption had higher levels of IL-6 (p = 0.002), IFN-γ (p = 0.018), and MCP-1 (p = 0.006), and lower levels of TGF-β1 (p = 0.017) compared with control patients. Inverse correlations were found between Proteobacteria abundance and TNF-α (R_s = -0.55, p = 0.02) and IL-8 (R_s = -0.58, p = 0.014), and between Faecalibacterium and MCP-1 levels (R_s = -0.56, p = 0.02) in the control patients, but not in patients with alcohol overconsumption. Patients with alcohol overconsumption reported more psychiatric symptoms, and these symptoms were inversely correlated with IL-10 levels. There were positive correlations between several of the assessed cytokines and biochemical liver variables, and negative correlations between cytokine levels and albumin.

CONCLUSION

Patients with alcohol overconsumption had a cytokine profile suggestive of increased systemic inflammatory activity, with higher levels of pro-inflammatory cytokines (IL-6, IFN-γ, and MCP-1) and lower levels of anti-inflammatory cytokines (TGF-β1). The findings may represent a link between alcohol use and alcohol-related morbidity.

Microbiota derived factors as drivers of type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease caused by complex interactions between host genetics and environmental factors, culminating in the T-cell mediated destruction of the insulin producing cells in the pancreas. The rapid increase in disease frequency over the past 50 years or more has been too rapid to attribute to genetics. Dysbiosis of the gut microbiota is currently being widely investigated as a major contributor to environmental change driving increased T1D onset. In this chapter, we discuss the major changes in gut microbiota composition and function linked to T1D risk as well as the potential origin of these changes including infant diet, antibiotic use and host genetics. We examine the interaction between inflammation and gut barrier function and the dysbiotic gut microbiota that have been linked to T1D.

Cytokine and goblet cell gene expression in equine cyathostomin infection and larvicidal anthelmintic therapy

AIMS

The role of the immune response to cyathostomin infections in horses remains unknown. Intestinal goblet cell hyperplasia has previously been noted as a component in cyathostomin infection; however, the function is unclear. The goal of this study was to evaluate the local and systemic gene expression to cyathostomin infections following larvicidal treatment and explore their relation to goblet cells.

METHODS AND RESULTS

Thirty-six ponies with naturally acquired cyathostomin infections were randomly allocated into three groups: fenbendazole-treated (10 mg/kg PO 5 days), moxidectin-treated (0.4 mg/kg PO once) and untreated control. Whole blood from all horses was collected weekly, and tissue samples from the large intestine collected during necropsy at 2 and 5 weeks post-treatment (WPT). Gene expression of interleukin (IL)-4, IL-5, IL-6, IL-10, IL-13, IL-17A, IL-22, IFN-γ, resistin-like molecule beta (RELM-β), Mucin 2 (MUC2) and tumour necrosis factor (TNF)-α was measured using qRT-PCR. There were statistically significant linear correlations between luminal worm burdens and MUC2 (r = -.2358) and RELM-β (r = -.2261).

CONCLUSION

This suggests an active role of immune system post-treatment in parasite expulsion, specifically in goblet cells, and that the organs respond differently to treatment and the larvae themselves. This may have implications in the disease process and treatment.

Sodium butyrate ameliorates insulin resistance and renal failure in CKD rats by modulating intestinal permeability and mucin expression

Background

The associated increase in the lipopolysaccharide (LPS) levels and uremic toxins in chronic kidney disease (CKD) has shifted the way we focus on intestinal microbiota. This study shows that a disruption of the intestinal barrier in CKD promotes leakage of LPS from the gut, subsequently decreasing insulin sensitivity. Butyrate treatment improved the intestinal barrier function by increasing colonic mucin and tight junction (TJ) proteins. This modulation further ameliorated metabolic functions such as insulin intolerance and improved renal function.

Methods

Renal failure was induced by 5/6th nephrectomy (Nx) in rats. A group of Nx and control rats received sodium butyrate in drinking water. The Nx groups were compared with sham-operated controls.

Results

The Nx rats had significant increases in serum creatinine, urea and proteinuria. These animals had impaired glucose and insulin tolerance and increased gluconeogenesis, which corresponded with decreased glucagon-like peptide-1 (GLP-1) secretion. The Nx animals suffered significant loss of intestinal TJ proteins, colonic mucin and mucin 2 protein. This was associated with a significant increase in circulating LPS, suggesting a leaky gut phenomenon. 5′adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, known to modulate epithelial TJs and glucose metabolism, was significantly reduced in the intestine of the Nx group. Anti-inflammatory cytokine, interleukin 10, anti-bacterial peptide and cathelicidin-related antimicrobial peptide were also lowered in the Nx cohort. Butyrate treatment increased AMPK phosphorylation, improved renal function and controlled hyperglycemia.

Conclusions

Butyrate improves AMPK phosphorylation, increases GLP-1 secretion and promotes colonic mucin and TJ proteins, which strengthen the gut wall. This decreases LPS leakage and inflammation. Taken together, butyrate improves metabolic parameters such as insulin resistance and markers of renal failure in CKD animals.

Human Milk Oligosaccharides Differently Modulate Goblet Cells Under Homeostatic, Proinflammatory Conditions and ER Stress

SCOPE

Human milk oligosaccharides (hMOs) have beneficial effects on intestinal barrier function, but the mechanisms of action are not well understood. Here, the effects of hMOs on goblet cells, which indicate that some hMOs may enhance mucus barrier function through direct modulation of goblet cell function, are studied.

METHODS AND RESULTS

The modulatory effects of 2'-fucosyllactose (2'-FL), 3-fucosyllactose (3-FL), lacto-N-triaose II (LNT2), and galacto-oligosaccharides (GOS) on the expression of goblet cell secretory related genes MUC2, TFF3, and RETNLB, and the Golgi-sulfotransferase genes CHST5 and GAL3ST2 of LS174T are determined by real-time quantitative RT-PCR. 3-FL, LNT2, and GOS-modulated LS174T gene expression profiles in a dose- and time-dependent manner. In addition, the upregulation of MUC2 is confirmed by immunofluorescence staining. Effects of 2'-FL, 3-FL, LNT2, and GOS on gene transcription of LS174T are also assessed during exposure to TNF-α, IL-13, or tunicamycin. During TNF-α challenge, 3-FL and LNT2 enhance MUC2 and TFF3 gene expression. After IL-13 exposure, 2'-FL, 3-FL, and LNT2 all show upregulating effects on MUC2; 3-FL and LNT2 also enhance TFF3 expression. LNT2 significantly reverses Tm-induced downregulation of TFF3, RETNLB, and CHST5.

CONCLUSION

The findings indicate that hMOs may enhance mucus barrier function through direct modulation of intestinal goblet cells. Effects are structure- and stressor-dependent.

Tight junctions in the development of asthma, chronic rhinosinusitis, atopic dermatitis, eosinophilic esophagitis, and inflammatory bowel diseases

This review focuses on recent developments related to asthma, chronic rhinosinusitis, atopic dermatitis (AD), eosinophilic esophagitis, and inflammatory bowel diseases (IBD), with a particular focus on tight junctions (TJs) and their role in the pathogenetic mechanisms of these diseases. Lung, skin, and intestinal surfaces are lined by epithelial cells that interact with environmental factors and immune cells. Therefore, together with the cellular immune system, the epithelium performs a pivotal role as the first line physical barrier against external antigens. Paracellular space is almost exclusively sealed by TJs and is maintained by complex protein-protein interactions. Thus, TJ dysfunction increases paracellular permeability, resulting in enhanced flux across TJs. Epithelial TJ dysfunction also causes immune cell activation and contributes to the pathogenesis of chronic lung, skin, and intestinal inflammation. Characterization of TJ protein alteration is one of the key factors for enhancing our understanding of allergic diseases as well as IBDs. Furthermore, TJ-based epithelial disturbance can promote immune cell behaviors, such as those in dendritic cells, Th2 cells, Th17 cells, and innate lymphoid cells (ILCs), thereby offering new insights into TJ-based targets. The purpose of this review is to illustrate how TJ dysfunction can lead to the disruption of the immune homeostasis in barrier tissues and subsequent inflammation. This review also highlights the various TJ barrier dysfunctions across different organ sites, which would help to develop future drugs to target allergic diseases and IBD.

Endoplasmic Reticulum Stress and Mitochondrial Function in Airway Smooth Muscle

Inflammatory airway diseases such as asthma affect more than 300 million people world-wide. Inflammation triggers pathophysiology via such as tumor necrosis factor α (TNFα) and interleukins (e.g., IL-13). Hypercontraction of airway smooth muscle (ASM) and ASM cell proliferation are major contributors to the exaggerated airway narrowing that occurs during agonist stimulation. An emergent theme in this context is the role of inflammation-induced endoplasmic reticulum (ER) stress and altered mitochondrial function including an increase in the formation of reactive oxygen species (ROS). This may establish a vicious cycle as excess ROS generation leads to further ER stress. Yet, it is unclear whether inflammation-induced ROS is the major mechanism leading to ER stress or the consequence of ER stress. In various diseases, inflammation leads to an increase in mitochondrial fission (fragmentation), associated with reduced levels of mitochondrial fusion proteins, such as mitofusin 2 (Mfn2). Mitochondrial fragmentation may be a homeostatic response since it is generally coupled with mitochondrial biogenesis and mitochondrial volume density thereby reducing demand on individual mitochondrion. ER stress is triggered by the accumulation of unfolded proteins, which induces a homeostatic response to alter protein balance via effects on protein synthesis and degradation. In addition, the ER stress response promotes protein folding via increased expression of molecular chaperone proteins. Reduced Mfn2 and altered mitochondrial dynamics may not only be downstream to ER stress but also upstream such that a reduction in Mfn2 triggers further ER stress. In this review, we summarize the current understanding of the link between inflammation-induced ER stress and mitochondrial function and the role played in the pathophysiology of inflammatory airway diseases.

TNFα selectively activates the IRE1α/XBP1 endoplasmic reticulum stress pathway in human airway smooth muscle cells

Airway inflammation is a key aspect of diseases such as asthma. Proinflammatory cytokines such as TNFα mediate the inflammatory response. In various diseases, inflammation leads to endoplasmic reticulum (ER) stress, the accumulation of unfolded proteins, which triggers homeostatic responses to restore normal cellular function. We hypothesized that TNFα triggers ER stress through an increase in reactive oxygen species generation in human airway smooth muscle (hASM) with a downstream effect on mitofusin 2 (Mfn2). In hASM cells isolated from lung specimens incidental to patient surgery, dose- and time-dependent effects of TNFα exposure were assessed. Exposure of hASM to tunicamycin was used as a positive control. Tempol (500 μM) was used as superoxide scavenger. Activation of three ER stress pathways were evaluated by Western blotting: 1) autophosphorylation of inositol-requiring enzyme1 (IRE1α) leading to splicing of X-box binding protein 1 (XBP1); 2) autophosphorylation of protein kinase RNA-like endoplasmic reticulum kinase (PERK) leading to phosphorylation of eukaryotic initiation factor 2α; and 3) translocation and cleavage of activating transcription factor 6 (ATF6). We found that exposure of hASM cells to tunicamycin activated all three ER stress pathways. In contrast, TNFα selectively activated the IRE1α/XBP1 pathway in a dose- and time-dependent fashion. Our results indicate that TNFα does not activate the PERK and ATF6 pathways. Exposure of hASM cells to TNFα also decreased Mfn2 protein expression. Concurrent exposure to TNFα and tempol reversed the effect of TNFα on IRE1α phosphorylation and Mfn2 protein expression. Selective activation of the IRE1α/XBP1 pathway in hASM cells after exposure to TNFα may reflect a unique homeostatic role of this pathway in the inflammatory response of hASM cells.

Rhubarb-Evoke Mucus Secretion through Aggregation and Degranulation of Mast Cell in the Colon of Rat: In vivo and ex vivo studies

Rhubarb is commonly used to treat constipation in China for its function of promoting intestinal movement and optimum water content in feces. However, its mechanism of mucus secretion is vague. The aim of the study is to investigate the role of mast cells and enteric neurons in rhubarb extract (RE)-induced mucus secretion in the rat colon. Immunofluorescence was used to detect histamine receptors. Western blotting and 3,3′-diaminobenzidine (DAB) were applied to explore the content changes of mast cells activation. The changes in colonic goblet cells (GCs) were determined by means of PAS/AB staining. An intestinal perfusion system with a Bradford protein assay kit was directly to estimate in vitro secretion. And the cytokines were investigated with ELISA. The longitudinal aspect of this study indicate that the number and water content of faecal pellets were enhanced after the administration of different doses of RE accompanied by mast cells accumulated and increased the content of interferon (IFN) -γ or decreased the levels of interleukin (IL) −10 at doses of 3 and 6 g/kg. Pretreatment with ketotifen, mast cell stabilizer, had partially inhibited on RE-induced mucus secretion. Furthermore, RE induced the release of acetylcholine and mucin-2 in the colonic tissue and the histamine levels from the faeces. The results suggest that RE induced colonic mucus secretion involves mast cell activation and some cytokine.

ER Stress and the UPR in Shaping Intestinal Tissue Homeostasis and Immunity

An imbalance in the correct protein folding milieu of the endoplasmic reticulum (ER) can cause ER stress, which leads to the activation of the unfolded protein response (UPR). The UPR constitutes a highly conserved and intricately regulated group of pathways that serve to restore ER homeostasis through adaptation or apoptosis. Numerous studies over the last decade have shown that the UPR plays a critical role in shaping immunity and inflammation, resulting in the recognition of the UPR as a key player in pathological processes including complex inflammatory, autoimmune and neoplastic diseases. The intestinal epithelium, with its many highly secretory cells, forms an important barrier and messenger between the luminal environment and the host immune system. It is not surprising, that numerous studies have associated ER stress and the UPR with intestinal diseases such as inflammatory bowel disease (IBD) and colorectal cancer (CRC). In this review, we discuss our current understanding of the roles of ER stress and the UPR in shaping immune responses and maintaining tissue homeostasis. Furthermore, the role played by the UPR in disease, with emphasis on IBD and CRC, is described here. As a key player in immunity and inflammation, the UPR has been increasingly recognized as an important pharmacological target in the development of therapeutic strategies for immune-mediated pathologies. We summarize available strategies targeting the UPR and their therapeutic implications. Understanding the balance between homeostasis and pathophysiology, as well as means of manipulating this balance, provides an important avenue for future research.

Functions and regulation of T cell-derived interleukin-10

Interleukin (IL)-10 is an essential anti-inflammatory cytokine and functions as a negative regulator of immune responses to microbial antigens. IL-10 is particularly important in maintaining the intestinal microbe-immune homeostasis. Loss of IL-10 promotes the development of inflammatory bowel disease (IBD) as a consequence of an excessive immune response to the gut microbiota. IL-10 also functions more generally to prevent excessive inflammation during the course of infection. Although IL-10 can be produced by virtually all cells of the innate and adaptive immune system, T cells constitute a non-redundant source for IL-10 in many cases. The various roles of T cell-derived IL-10 will be discussed in this review. Given that IL-10 is at the center of maintaining the delicate balance between effective immunity and tissue protection, it is not surprising that IL-10 expression is highly dynamic and tightly regulated. We summarize the environmental signals and molecular pathways that regulate IL-10 expression. While numerous studies have provided us with a deep understanding of IL-10 biology, the majority of findings have been made in murine models, prompting us to highlight gaps in our knowledge about T cell-derived IL-10 in the human system.

Increased grp78 transcription is correlated to reduced tlr4 transcription in patients surviving sepsis

Regulated transcriptional readthrough during stress maintains genome structure and ensures access to genes that are necessary for cellular recovery. A broad number of genes, including of the bacterial sensor Toll-like receptor 4 (TLR-4), are markedly transcribed on initiating the systemic inflammatory response. Here we study the transcriptional patterns of tlr4 and of its modulator grp78 during human sepsis, and establish their correlations with the outcome of patients. We measured the daily tlr4 and grp78 RNA expression levels in peripheral blood of septic patients, immediately after admission to intensive care, and modeled these RNA values with a sine damping function. We obtained negative correlations between the transcription of tlr4 and grp78 RNA in the survivor group. In contrast, such relation is lost in the deceased patients. Loss of transcriptional homeostasis predicted by our model within the initial 4 days of hospitalization was confirmed by death of those patients up to 28 days later.