Intestinal barrier damage caused by trauma and lipopolysaccharide

Protective effect of zinc gluconate on intestinal mucosal barrier injury in antibiotics and LPS-induced mice

Objective

The aim of the study is to investigate the function and mechanism of Zinc Gluconate (ZG) on intestinal mucosal barrier damage in antibiotics and Lipopolysaccharide (LPS)-induced mice.

Methods

We established a composite mouse model by inducing intestinal mucosal barrier damage using antibiotics and LPS. The animals were divided into five groups: Control (normal and model) and experimental (low, medium, and high-dose ZG treatments). We evaluated the intestinal mucosal barrier using various methods, including monitoring body weight and fecal changes, assessing pathological damage and ultrastructure of the mouse ileum, analyzing expression levels of tight junction (TJ)-related proteins and genes, confirming the TLR4/NF-κB signaling pathway, and examining the structure of the intestinal flora.

Results

In mice, the dual induction of antibiotics and LPS led to weight loss, fecal abnormalities, disruption of ileocecal mucosal structure, increased intestinal barrier permeability, and disorganization of the microbiota structure. ZG restored body weight, alleviated diarrheal symptoms and pathological damage, and maintained the structural integrity of intestinal epithelial cells (IECs). Additionally, ZG reduced intestinal mucosal permeability by upregulating TJ-associated proteins (ZO-1, Occludin, Claudin-1, and JAM-A) and downregulating MLCK, thereby repairing intestinal mucosal barrier damage induced by dual induction of antibiotics and LPS. Moreover, ZG suppressed the TLR4/NF-κB signaling pathway, demonstrating anti-inflammatory properties and preserving barrier integrity. Furthermore, ZG restored gut microbiota diversity and richness, evidenced by increased Shannon and Observed features indices, and decreased Simpson's index. ZG also modulated the relative abundance of beneficial human gut bacteria (Bacteroidetes, Firmicutes, Verrucomicrobia, Parabacteroides, Lactobacillus, and Akkermansia) and harmful bacteria (Proteobacteria and Enterobacter), repairing the damage induced by dual administration of antibiotics and LPS.

Conclusion

ZG attenuates the dual induction of antibiotics and LPS-induced intestinal barrier damage and also protects the intestinal barrier function in mice.

Effects of hindgut acidosis on production, metabolism, and inflammatory biomarkers in previously immune-activated lactating dairy cows

Previous stressors and systemic inflammation may increase the intestine's susceptibility to hindgut acidosis (HGA). Therefore, our experimental objectives were to evaluate the effects of isolated HGA on metabolism, production, and inflammation in simultaneously immune-activated lactating cows. Twelve rumen-cannulated Holstein cows (118 ± 41 d in milk; 1.7 ± 0.8 parity) were enrolled in a study with 3 experimental periods (P). Baseline data were collected during P1 (5 d). On d 1 of P2 (2 d), all cows received an i.v. lipopolysaccharide (LPS) bolus (0.2 µg/kg of body weight; BW). During P3 (4 d), cows were randomly assigned to 1 of 2 abomasal infusion treatments: (1) control (LPS-CON; 6 L of H₂O/d; n = 6) or (2) starch infused (LPS-ST; 4 kg of corn starch + 6 L of H₂O/d; n = 6). Treatments were allocated into 4 equal doses (1.5 L of H₂O or 1 kg of starch and 1.5 L of H₂O, respectively) and administered at 0000, 0600, 1200, and 1800 h daily. Additionally, both treatments received i.v. LPS on d 1 and 3 of P3 (0.8 and 1.6 µg/kg of BW, respectively) to maintain an inflamed state. Effects of treatment, time, and their interaction were assessed. Repeated LPS administration initiated and maintained an immune-activated state, as indicated by increased circulating white blood cells (WBC), serum amyloid A (SAA), and LPS-binding protein (LBP) during P2 and P3 (29%, 3-fold, and 50% relative to P1, respectively) for both abomasal infusion treatments. Regardless of abomasal treatment, milk yield and dry matter intake were decreased throughout P2 and P3 but with lesser severity following each LPS challenge (54, 44, and 37%, and 49, 42, and 40% relative to baseline on d 1 of P2, d 1 and d 3 of P3, respectively). As expected, starch infusions markedly decreased fecal pH (5.56 at nadir vs. 6.57 during P1) and increased P3 fecal starch relative to LPS-CON (23.7 vs. 2.4% of dry matter). Neither LPS nor starch infusions altered circulating glucose, insulin, nonesterified fatty acids, or β-hydroxybutyrate, although LPS-ST cows had decreased blood urea nitrogen throughout P3 (16% relative to LPS-CON). Despite the striking reduction in fecal pH, HGA had no additional effect on circulating WBC, SAA, or LBP. Thus, in previously immune-activated dairy cows, HGA did not augment the inflammatory state, as indicated by a lack of perturbations in production, metabolism, and inflammatory biomarkers.

Dietary Histamine Impairs the Digestive Physiology Function and Muscle Quality of Hybrid Grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂)

An 8-week feeding experiment was conducted to investigate the effect of dietary histamine on growth performance, digestive physiology function and muscle quality in a hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂). Seven isoproteic (50%) and isolipidic (11%) diets were prepared with various histamine inclusion levels of 0, 30, 60, 120, 240, 480 and 960 mg/kg in diets (actual contents were 72.33, 99.56, 138.60, 225.35, 404.12, 662.12 and 1245.38 mg/kg), respectively. Each diet was randomly assigned to triplicates of 30 juveniles (average body weight 14.78 g) per tank in a flow-through mariculture system. The increase in the dietary histamine level up to 1245.38 mg/kg made no significant difference on the growth rate and feed utilization of the grouper. However, the increased histamine content linearly decreased the activities of digestive enzymes, while no differences were observed in groups with low levels of histamine (≤404.12 mg/kg). Similarly, high levels of histamine (≥404.12 mg/kg) significantly damaged the gastric and intestinal mucosa, disrupted the intestinal tight junction structure, and raised the serum diamine oxidase activity and endotoxin level. Meanwhile, high doses of histamine (≥662.12 mg/kg) significantly reduced the activities of antioxidant enzymes, upregulated the relative expression of Kelch-like ECH-associated protein 1, and hardened and yellowed the dorsal muscle of grouper. These results showed that dietary histamine was detrimental to the digestive physiology function and muscle quality of the grouper, although it did compromise its growth performance.

New insights into lipopolysaccharide inactivation mechanisms in sepsis

The complex pathophysiology of sepsis makes it a syndrome with limited therapeutic options and a high mortality rate. Gram-negative bacteria containing lipopolysaccharides (LPS) in their outer membrane correspond to the most common cause of sepsis. Since the gut is considered an important source of LPS, intestinal damage has been considered a cause and a consequence of sepsis. Although important in the maintenance of the intestinal epithelial cell homeostasis, the microbiota has been considered a source of LPS. Recent studies have started to shed light on how sepsis is triggered by dysbiosis, and an increased inflammatory state of the intestinal epithelial cells, expanding the understanding of the gut-liver axis in sepsis. Here, we review the gut-liver interaction in Gram-negative sepsis, exploring the mechanisms of LPS inactivation, including the recently described contribution of an isoform of the cholesteryl-ester transfer protein (CETPI). Although several key questions remain to be answered when the pathophysiology of sepsis is reviewed, new contributions coming to light exploring the way LPS might be inactivated in vivo, suggest that new applications might soon reach the clinical setting.

What we already know about rhubarb: a comprehensive review

Rhubarb (also named Rhei or Dahuang), one of the most ancient and important herbs in traditional Chinese medicine (TCM), belongs to the Rheum L. genus from the Polygonaceae family, and its application can be traced back to 270 BC in "Shen Nong Ben Cao Jing". Rhubarb has long been used as an antibacterial, anti-inflammatory, anti-fibrotic and anticancer medicine in China. However, for a variety of reasons, such as origin, variety and processing methods, there are differences in the effective components of rhubarb, which eventually lead to decreased quality and poor efficacy. Additionally, although some papers have reviewed the relationship between the active ingredients of rhubarb and pharmacologic actions, most studies have concentrated on one or several aspects, although there has been great progress in rhubarb research in recent years. Therefore, this review aims to summarize recent studies on the geographic distribution, taxonomic identification, pharmacology, clinical applications and safety issues related to rhubarb and provide insights into the further development and application of rhubarb in the future.

Bacterial Endotoxins and Their Role in Periparturient Diseases of Dairy Cows: Mucosal Vaccine Perspectives

During the periparturient period there is a significant increase in the incidence of multiple metabolic and infectious diseases in dairy cows. Dairy cows are fed high-grain diets immediately after calving to support production of large amounts of milk. Mounting evidence indicates these types of diets are associated with the release of high amounts of endotoxins in the rumen fluid. If infected, the udder and uterus additionally become important sources of endotoxins during the postpartum period. There is increasing evidence that endotoxins translocate from rumen, uterus, or udder into the systemic circulation and trigger chronic low-grade inflammatory conditions associated with multiple diseases including fatty liver, mastitis, retained placenta, metritis, laminitis, displaced abomasum, milk fever, and downer cow syndrome. Interestingly, endotoxin-related diseases are triggered by a bacterial component and not by a specific bacterium. This makes prevention of these type of diseases different from classical infectious diseases. Prevention of translocation of endotoxins into the host systemic circulation needs to take priority and this could be achieved with a new approach: mucosal vaccination. In this review article, we discuss all the aforementioned issues in detail and also report some of our trials with regards to mucosal vaccination of periparturient dairy cows.

Influence of Mushroom Polysaccharide, Nano-Copper, Copper Loaded Chitosan, and Lysozyme on Intestinal Barrier and Immunity of LPS-mediated Yellow-Feathered Chickens

This study investigated the influence of dietary supplementation with some antibiotic alternatives on growth performance, intestinal barrier, and immunity of lipopolysaccharide (LPS) challenged chicks. Wenshi females, aged 4 days, were allocated randomly into eight groups, each with six replicates of 20 birds (n = 120/treatment), which received a basal diet supplemented with 0 (control), 0 (LPS), 200 mg/kg aureomycin, 50 mg/kg mushroom polysaccharide, 100 mg/kg mushroom polysaccharide, 500 mg/kg nano-copper, 300 mg/kg copper loaded chitosan, and 500 mg/kg lysozyme for 21 days. On day 18 and 20, the control birds were injected with 0.5 mL saline solution, the other treatments were injected with 0.5 mL saline containing 500 µg LPS/kg body weight (BW). The results indicated that LPS treatment reduced the BW, average daily gain (ADG), and daily feed intake (ADFI) than the controls (p < 0.05), and the antibiotic and the tested alternatives could not retrieve the normal BW, ADG, and ADFI. The tested additives reduced several negative effects of LPS; they reduced diamine oxidase activity and inflammatory mediators in plasma, jejunal mucosa, spleen and thymus, increased content of immunoglobulin in plasma and jejunal mucosa, and decreased gene expression of inducible nitric oxide synthase and Cyclooxygenase 2 in jejunal mucosa.

Mus musculus deficient for secretory antibodies show delayed growth with an altered urinary metabolome

Background

The polymeric immunoglobulin receptor (pIgR) maintains the integrity of epithelial barriers by transporting polymeric antibodies and antigens through the epithelial mucosa into the lumen. In this study, we examined the role of pIgR in maintaining gut barrier integrity, which is important for the normal development in mice.

Methods

Cohorts of pIgR^−/− mice and their wildtype controls were housed under Specific Pathogen Free (SPF) conditions and monitored for weight gain as an indicator of development over time. The general physiology of the gastrointestinal tract was analysed using immunohistochemistry in young (8–12 weeks of age) and aged mice (up to 18 months of age), and the observed immunopathology in pIgR^−/− mice was further characterised using flow cytometry. Urinary metabolites were analysed using gas chromatography-mass spectrometry (GC-MS), which revealed changes in metabolites that correlated with age-related increase in gut permeability in pIgR^−/− mice.

Results

We observed that pIgR^−/− mice exhibited delayed growth, and this phenomenon is associated with low-grade gut inflammation that increased with ageing. The gross intraepithelial lymphocytic (IEL) infiltration characteristic of pIgR^−/− mice was redefined as CD8α⁺αβ⁺ T cells, the majority of which expressed high levels of CD103 and CD69 consistent with tissue resident memory T cells (T_RM). Comparison of the urinary metabolome between pIgR^−/− and wild-type mice revealed key changes in urinary biomarkers fucose, glycine and Vitamin B5, suggestive of altered mucosal permeability. A significant increase in gut permeability was confirmed by analysing the site-specific uptake of sugar probes in different parts of the intestine.

Conclusion

Our data show that loss of the secretory antibody system in mice results in enhanced accumulation of inflammatory IELs in the gut, which likely reflects ongoing inflammation in reaction to gut microbiota or food antigens, leading to delayed growth in pIgR^−/− mice. We demonstrate that this leads to the presence of a unique urinary metabolome profile, which may provide a biomarker for altered gut permeability.

Electronic supplementary material

The online version of this article (10.1186/s10020-019-0077-2) contains supplementary material, which is available to authorized users.

Invited review: Role of bacterial endotoxins in the etiopathogenesis of periparturient diseases of transition dairy cows

The dairy industry continues to suffer severe economic losses due to the increased disease incidence cows experience during the transition period. It has long been the classical view that the major contributing factor to the development of these periparturient diseases is the considerable increase in nutritional demands for milk production. This classical view, however, fails to account for the substantial correlation between both metabolic and infectious diseases and the detrimental effects that can occur with the provision of high-energy diets to support these nutritional demands. Currently, increasing evidence implicates bacterial endotoxins in the etiopathology of most periparturient diseases. Bacterial endotoxins are components of the outer cell wall of gram-negative and gram-positive bacteria that are highly immunostimulatory and can trigger proinflammatory immune responses. The ability of endotoxins to translocate from the mucosal tissues, including the gastrointestinal tract, mammary gland, and uterus, into the systemic circulation has been observed. Once they have entered the circulation, endotoxins potentially contribute to disease either directly, through eliciting an inflammatory response, or indirectly through other factors such as the overreaction of the natural protective mechanisms of the host. Although the evidence implicating a role of endotoxins in the pathogenesis of transition diseases continues to grow, our current knowledge of the host response to mucosal endotoxin exposure and pathogenic mechanisms remain largely unknown. Developing our understanding of the connection between endotoxemia and dairy cattle disease holds significant potential for the future development of preventative measures that could benefit the productivity of the dairy industry as well as animal welfare.

Mechanisms by which Stress Affects the Experimental and Clinical Inflammatory Bowel Disease (IBD): Role of Brain-Gut Axis

BACKGROUND

Stress of different origin is known to alter so called "braingut axis" and contributes to a broad array of gastrointestinal disorders including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and other functional gastrointestinal diseases. The stressful situations and various stressors including psychosocial events, heat, hypo- and hyperthermia may worsen the course of IBD via unknown mechanism. The aims of this paper were to provide an overview of experimental and clinical evidences that stress activates the brain-gut axis which results in a mucosal mast cells activation and an increase in the production of proinflammatory cytokines and other endocrine and humoral mediators.

METHODS

Research and online content related to effects of stress on lower bowel disorders are reviewed and most important mechanisms are delineated.

RESULTS

Brain conveys the neural, endocrine and circulatory messages to the gut via brain-gut axis reflecting changes in corticotrophin releasing hormone, mast cells activity, neurotransmission at the autonomic nerves system and intestinal barrier function all affecting the pathogenesis of animal colitis and human IBD. Stress triggers the hypothalamus-pituitary axis and the activation of the autonomic nervous system, an increase in cortisol levels and proinflammatory cytokines such as tumor necrosis factor-alpha, interleukin-8, interleukin-1beta and interleukin-6.

CONCLUSION

The acute or chronic stress enhances the intestinal permeability weakening of the tight junctions and increasing bacterial translocation into the intestinal wall. An increased microbial load in the colonic tissue, excessive cytokine release and a partially blunted immune reactivity in response to stress result in its negative impact on IBD.

Effect of sodium butyrate on intestinal inflammatory response to lipopolysaccharide in broiler chickens

Jiang, Y., Zhang, W., Gao, F. and Zhou, G. 2015. Effect of sodium butyrate on intestinal inflammatory response to lipopolysaccharide in broiler chickens. Can. J. Anim. Sci. 95: 389–395. The aim of this study was to investigate the effect of sodium butyrate (SB) supplementation on intestinal inflammatory response to lipopolysaccharide (LPS) in broiler chickens. A total of 120 one-day-old chickens (Arbor Acres) were divided into two groups and fed a control diet (without SB) or 1.00 g SB kg−1 diet. Half of the chickens fed each diet were injected intra-peritoneally with 0.5 g kg−1 body weight of Escherichia coli LPS at 16, 18 and 20 d of age. The results showed that the LPS challenge decreased (P<0.05) villus height and the ratio of villus height to crypt depth (V/C ratio), increased (P<0.01) crypt depth of the duodenum. SB supplementation increased (P<0.05) villus height, crypt depth and V/C ratio of the duodenum and jejunum, except for the crypt depth of the jejunum. The LPS challenge increased (P<0.05) myeloperoxidase (MPO) activities, intercellular adhesion molecule-1 (ICAM-1) and activated nuclear factor kappa B (NF-κB) levels in mucosa of the duodenum and jejunum, while decreasing (P<0.05) insulin-like growth factor-1 (IGF-1) concentrations. The LPS challenge increased (P<0.05) the mRNA levels of interleukin-1beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) in duodenal mucosa. SB supplementation decreased (P<0.05) the MPO activities and mRNA expression of TNF-α in the duodenal mucosa, and the activated NF-κB levels in mucosa of the duodenum and jejunum. There were no significant interactions between dietary SB and LPS on the histomorphology of the small intestine and those inflammatory mediators except for MPO and ICAM-1 in duodenal mucosa (P<0.05). The results indicate that SB supplementation could improve the intestinal morphology and function of broiler chickens and partially attenuate inflammatory responses caused by LPS challenge but not involving NF-κB activation.

Regional susceptibility to stress-induced intestinal injury in the mouse

Injury to the intestinal mucosa is a life-threatening problem in a variety of clinical disorders, including hemorrhagic shock, trauma, burn, pancreatitis, and heat stroke. The susceptibility to injury of different regions of intestine in these disorders is not well understood. We compared histological injury across the small intestine in two in vivo mouse models of injury, hemorrhagic shock (30% loss of blood volume) and heat stroke (peak core temperature 42.4°C). In both injury models, areas near the duodenum showed significantly greater mucosal injury and reductions in villus height. To determine if these effects were dependent on circulating factors, experiments were performed on isolated intestinal segments to test for permeability to 4-kDa FITC-dextran. The segments were exposed to hyperthermia (42°C for 90 min), moderate simulated ischemia (Po2 ∼30 Torr, Pco2 ∼60 Torr, pH 7.1), severe ischemia (Po2 ∼20 Torr, Pco2 ∼80 Torr, pH 6.9), or severe hypoxia (Po2 ∼0 Torr, Pco2 ∼35 Torr) for 90 min, and each group was compared with sham controls. All treatments resulted in marked elevations in permeability within segments near the duodenum. In severe hypoxia or hyperthermia, permeability was also moderately elevated in the jejunum and ileum; in moderate or severe ischemia, permeability was unaffected in these regions. The results demonstrate increased susceptibility of proximal regions of the small intestine to acute stress-induced damage, irrespective of circulating factors. The predominant injury in the duodenum may impact the pattern of acute inflammatory responses arising from breach of the intestinal barrier, and such knowledge may be useful for designing therapeutic strategies.

Bacillus cereus var. toyoi promotes growth, affects the histological organization and microbiota of the intestinal mucosa in rainbow trout fingerlings

In this preliminary study, we evaluated the effects of a gram-positive soil bacteria Bacillus cereus var. toyoi on the growth performance, digestive enzyme activities, intestinal morphology, and microbiota in rainbow trout Oncorhynchus mykiss fingerlings. Trout were maintained in a recirculation system and fed 2 diets: 1) a commercial trout feed deprived of the probiotic and 2) the same diet but with the spores of the probiotic bacteria dissolved in fish oil during the manufacturing of the feed (final concentration = 2 × 10(4) cfu/g). Each diet was tested in three 400-L cylindroconical tanks (125 fish per tank; initial density = 1.3 kg/m(3); 13.2°C) for a period of 93 d. The probiotic-supplemented diet promoted growth, and the final mean BW and standard length in fish fed the probiotic were 3.4% and 2.1%, respectively, which was greater than the control group (P < 0.05). Fish fed the probiotic showed a more homogeneous distribution in the final BW, with a greater frequency of individuals around the modal of the normal distribution of the population. This result is of practical importance because homogenous production lots can improve rearing practices, reducing hierarchical dominance situations arising from individuals of larger sizes. In addition, the probiotic-supplemented diet increased the level of leukocyte infiltration in the lamina propria of the intestinal mucosa, the number of goblet cells (P < 0.010), and villi height (P < 0.001) but did not affect villi width. The administration of the probiotic changed the intestinal microbiota as indicated by 16S rDNA PCR-restriction fragment length polymorphism. In this sense, fish fed the probiotic formed a well-defined cluster composed of 1 super clade, whereas compared control fish had a greater degree of diversity in their gut microbiota. These changes in gut microbiota did not affect the specific activity of selected pancreatic and intestinal digestive enzymes. These results indicate that the inclusion of the probiotic bacteria in trout feeds could be beneficial for the host by enhancing its intestinal innate immune function and promoting growth.

Evaluation of In Vitro Anti-Inflammatory Activities and Protective Effect of Fermented Preparations of Rhizoma Atractylodis Macrocephalae on Intestinal Barrier Function against Lipopolysaccharide Insult

Lipopolysaccharide (LPS), a potent inducer of systemic inflammatory responses, is known to cause impairment of intestinal barrier function. Here, we evaluated the in vitro protective effect of an unfermented formulation of Rhizoma Atractylodis Macrocephalae (RAM), a traditional Chinese herbal medicine widely used in the treatment of many digestive and gastrointestinal disorders, and two fermented preparations of RAM, designated as FRAM-1 (prepared in Luria-Bertani broth) and FRAM-2 (prepared in glucose), on intestinal epithelial cells (IECs) against LPS insult. In general, fermented formulations, especially FRAM-2, but not unfermented RAM, exerted an appreciable protective effect on IECs against LPS-induced perturbation of membrane resistance and permeability. Both fermented formulations exhibited appreciable anti-inflammatory activities in terms of their ability to inhibit LPS-induced gene expression and induced production of a number of key inflammatory mediators and cytokines in RAW 264.7 macrophage cells. However, in most cases, FRAM-2 exhibited stronger anti-inflammatory effects than FRAM-1. Our findings also suggest that suppression of nuclear factor- κ β (NF- κ β ) activity might be one of the possible mechanisms by which the fermented RAM exerts its anti-inflammatory effects. Collectively, our results highlight the benefits of using fermented products of RAM to protect against LPS-induced inflammatory insult and impairment in intestinal barrier function.

Pathogenesis and treatment of parenteral nutrition-associated liver disease

BACKGROUND

Parenteral nutrition-associated liver disease (PNALD) has been common in patients who require long-term parenteral nutrition. PNALD develops in 40%-60% of infants on long-term parenteral nutrition compared with 15%-40% of adults on home parenteral nutrition for intestinal failure. The pathogenesis of PNALD is multifactorial and remains unclear. There is no specific treatment. Management strategies for its prevention and treatment depend on an understanding of many risk factors. This review aims to provide an update on the pathogenesis and treatment of this disease.

DATA SOURCES

A literature search was performed on the MEDLINE and Web of Science databases for articles published up to October 2011, using the keywords: parenteral nutrition associated liver disease, intestinal failure associated liver disease, lipid emulsions and fish oil. The available data reported in the relevant literatures were analyzed.

RESULTS

The literature search provided a huge amount of evidence about the pathogenesis and management strategies on PNALD. Currently, lack of enteral feeding, extended duration of parenteral nutrition, recurrent sepsis, and nutrient deficiency or excess may play important roles in the pathogenesis of PNALD. Recent studies found that phytosterols, present as contaminants in soy-based lipid emulsions, are also an important factor in the pathogenesis. Moreover, the treatment of PNALD is discussed.

CONCLUSIONS

The use of lipid emulsions, phytosterols in particular, is associated with PNALD. Management strategies for the prevention and treatment of PNALD include consideration of early enteral feeding, the use of specialized lipid emulsions such as fish oil emulsions, and isolated small bowel or combined liver and small bowel transplantation. A greater understanding of the pathogenesis of PNALD has led to promising interventions to prevent and treat this condition. Future work should aim to better understand the mechanisms of PNALD and the long-term outcomes of its treatment.

Therapeutic effect of Tripterygium wilfordii Hook F multiglycosides on gut barrier dysfunction in rats with acute necrotizing pancreatitis

The aim of the current study was to investigate the therapeutic effect of Tripterygium wilfordii Hook F multiglycosides (TWG) on gut barrier dysfunction in rats with acute necrotizing pancreatitis (ANP). ANP was induced in rats using 3.5% sodium taurocholate. The rats were divided into 3 groups: the sham operation (SO), ANP and ANP+TWG groups. Biochemical and pathological change of pancreatic tissue and ileal mucosa, bacterial cultures and the survival rate were measured following surgery and treatment. TWG treatment significantly decreased amylase and lipase activities and plasma endotoxin and D-lactate levels. Edema and inflammation in the pancreas and ileal mucosa were alleviated. Positive bacterial cultures were significantly reduced. The survival rate of the rats in the ANP+TWG group was higher than that of the rats in the ANP group. TWG treatment showed beneficial effects by protecting the pancreas from bacterial infection caused by gut barrier dysfunction and improving the outcomes of the rats with ANP.

The regulation of interleukin-6 implicates skeletal muscle as an integrative stress sensor and endocrine organ

Skeletal muscle has been identified as an endocrine organ owing to its capacity to produce and secrete a variety of cytokines (myokines) and other proteins. To date, myokines have primarily been studied in response to exercise or metabolic challenges; however, numerous observations suggest that skeletal muscle may also release myokines in response to certain categories of internal or external stress exposure. Internal stress signals include oxidative or nitrosative stress, damaged or unfolded proteins, hyperthermia or energy imbalance. External stress signals, which act as indicators of organismal stress or injury in other cells, employ mediators such as catecholamines, endotoxin, alarmins, ATP and pro-inflammatory cytokines, such as tumour necrosis factor-α and interleukin-1β. External stress signals generally induce cellular responses through membrane receptor systems. In this review, we focus on the regulation of interleukin-6 (IL-6) as a prototypical stress response myokine and highlight evidence that IL-6 gene regulation in muscle is inherently organized to respond to a wide variety of internal and external stressors. Given that IL-6 can initiate protective, anti-inflammatory or restorative processes throughout the organism during life-threatening conditions, we present the argument that skeletal muscle has a physiological function as a sensor and responder to stress. Furthermore, we hypothesize that it may comprise a fundamental component of the organism's acute stress response.

Effect of l-arginine on intestinal mucosal immune barrier function in weaned pigs after Escherichia coli LPS challenge

The effects of l-arginine (Arg) supplementation on intestinal mucosal immune barrier function in weaned pigs after Escherichia coli LPS challenge were evaluated. Twenty-four weaned pigs were allotted to four treatments including: (i) non-challenged control; (ii) LPS-challenged control; (iii) LPS + 0.5% Arg; and (iv) LPS + 1.0% Arg. On d 16, pigs in the LPS, LPS + 0.5% Arg and LPS + 1.0% Arg groups were challenged by injection with 100 µg/kg of body mass LPS, whereas the control group were given sterile saline. At 48 h post-challenge, all pigs were sacrificed for evaluation of small intestinal morphology and mucosal immune barrier function. In the jejunum and ileum, LPS caused villous atrophy and intestinal morphology disruption, whereas 0.5% or 1.0% Arg supplementation mitigated villus atrophy and intestinal morphology impairment caused by LPS challenge. Arg (0.5%) supplementation increased the numbers of IgA-secreting cells, CD8+ and CD4+ T cells in the ileum ( P < 0.05). Arg supplementation prevented the elevation of mast cell numbers induced by LPS challenge ( P < 0.05). Dietary supplementation of Arg caused a decreased lymphocyte apoptosis of Peyer’s patches in pigs challenged by LPS ( P < 0.05). These results indicated that Arg supplementation protects and enhances intestinal mucosal immune barrier function and maintains intestinal integrity in weaned pigs after E. coli LPS challenge.

Stress and animal models of inflammatory bowel disease--an update on the role of the hypothalamo-pituitary-adrenal axis

Chronic psychosocial stress has been repeatedly shown in humans to be a risk factor for the development of several affective and somatic disorders, including inflammatory bowel diseases (IBD). There is also a large body of evidence from rodent studies indicating a link between stress and gastrointestinal dysfunction, resembling IBD in humans. Despite this knowledge, the detailed underlying neuroendocrine mechanisms are not sufficiently understood. This is due, in part, to a lack of appropriate animal models, as most commonly used rodent stress paradigms do not adequately resemble the human situation and/or do not cause the development of spontaneous colitis. Therefore, our knowledge regarding the link between stress and IBD is largely based on rodent models with low face and predictive validity, investigating the effects of unnatural stressors on chemically induced colitis. These studies have consistently reported that hypothalamo-pituitary-adrenal (HPA) axis activation during stressor exposure has an ameliorating effect on the severity of a chemically induced colitis. However, to show the biological importance of this finding, it needs to be replicated in animal models employing more clinically relevant stressors, themselves triggering the development of spontaneous colitis. Important in view of this, recent studies employing chronic/repeated psychosocial stressors were able to demonstrate that such stressors indeed cause the development of spontaneous colitis and, thus, represent promising tools to uncover the mechanisms underlying stress-induced development of IBD. Interestingly, in these models the development of spontaneous colitis was paralleled by decreased anti-inflammatory glucocorticoid (GC) signaling, whereas adrenalectomy (ADX) prior to stressor exposure prevented its development. These findings suggest a more complex role of the HPA axis in the development of spontaneous colitis. In the present review I summarize the available human and rodent data in order to provide a comprehensive understanding of the biphasic role of the HPA axis and/or the GC signaling during stressor exposure in terms of spontaneous colitis development.

Mucosal immunosuppression and epithelial barrier defects are key events in murine psychosocial stress-induced colitis

Chronic psychosocial stress is a risk factor for many affective and somatic disorders, including inflammatory bowel diseases. In support chronic subordinate colony housing (CSC, 19 days), an established mouse model of chronic psychosocial stress, causes the development of spontaneous colitis. However, the mechanisms underlying the development of such stress-induced colitis are poorly understood. Assessing several functional levels of the colon during the initial stress phase, we show a pronounced adrenal hormone-mediated local immune suppression, paralleled by impaired intestinal barrier functions, resulting in enhanced bacterial load in stool and colonic tissue. Moreover, prolonged treatment with broad-spectrum antibiotics revealed the causal role of these early maladaptations in the development of stress-induced colitis. Together, we demonstrate that translocation of commensal bacteria is crucial in the initiation of stress-induced colonic inflammation. However, aggravation by the immune-modulatory effects of fluctuating levels of adrenal hormones is required to develop this into a full-blown colitis.

Vasoactive intestinal peptide promotes gut barrier function against severe acute pancreatitis

To explore the influence of vasoactive intestinal peptide (VIP) on the gut barrier function in severe acute pancreatitis (SAP). Fifty four SD rats were randomly divided into three groups: sham operated (SO) group, SAP group and VIP intervention group. Each group was further divided into three time points: 1, 6 and 12 h after operation with 6 rats for each treatment point. SAP models were induced by retrograde injection of 4% sodium taurocholate into the bili-pancreatic duct. VIP intervention group was made by 5 nmol VIP intraperitoneal injection within 5 min after SAP model successfully obtained. The VIP in plasma and intestinal homogenate were detected with ELISA. The endotoxin in plasma of all groups was also tested. The expression levels of TLR4, TNF-α, IL-6, and IL-10 in gut mucosa were measured by RT-PCR. Meanwhile intestinal samples were harvested for pathological examination. Compared to SO group, the VIP in plasma and intestinal homogenate of SAP group were significantly decreased at 1 h after induction, and then gradually increased to beyond the level of SO group at 12 h. The endotoxin of SAP group was continually increased. The mRNA levels of TLR4, TNF-α, IL-6, and IL-10 were also increased with obvious pathological injuries in the intestine. In the VIP group, endotoxin in plasma was obviously decreased compared to SAP group. The expressions of TNF-α, IL-6 mRNA were suppressed while IL-10mRNA was increased. The intestinal pathological injuries were also markedly alleviated. These results suggested that VIP had protective effects on SAP gut barrier function through inhibiting intestinal mucosal inflammatory responses.

TGF-β limits IL-33 production and promotes the resolution of colitis through regulation of macrophage function

Mϕs promote tissue injury or repair depending on their activation status and the local cytokine milieu. It remains unclear whether the immunosuppressive effects of transforming growth factor β (TGF-β) serve a nonredundant role in Mϕ function in vivo. We generated Mϕ-specific transgenic mice that express a truncated TGF-β receptor II under control of the CD68 promoter (CD68TGF-βDNRII) and subjected these mice to the dextran sodium sulfate (DSS) model of colitis. CD68TGF-βDNRII mice have an impaired ability to resolve colitic inflammation as demonstrated by increased lethality, granulocytic inflammation, and delayed goblet cell regeneration compared with transgene negative littermates. CD68TGF-βDNRII mice produce significantly less IL-10, but have increased levels of IgE and numbers of IL-33+ Mϕs than controls. These data are consistent with associations between ulcerative colitis and increased IL-33 production in humans and suggest that TGF-β may promote the suppression of intestinal inflammation, at least in part, through direct effects on Mϕ function.

TGF-β limits IL-33 production and promotes the resolution of colitis through regulation of macrophage function

Mϕs promote tissue injury or repair depending on their activation status and the local cytokine milieu. It remains unclear whether the immunosuppressive effects of transforming growth factor β (TGF-β) serve a nonredundant role in Mϕ function in vivo. We generated Mϕ-specific transgenic mice that express a truncated TGF-β receptor II under control of the CD68 promoter (CD68TGF-βDNRII) and subjected these mice to the dextran sodium sulfate (DSS) model of colitis. CD68TGF-βDNRII mice have an impaired ability to resolve colitic inflammation as demonstrated by increased lethality, granulocytic inflammation, and delayed goblet cell regeneration compared with transgene negative littermates. CD68TGF-βDNRII mice produce significantly less IL-10, but have increased levels of IgE and numbers of IL-33+ Mϕs than controls. These data are consistent with associations between ulcerative colitis and increased IL-33 production in humans and suggest that TGF-β may promote the suppression of intestinal inflammation, at least in part, through direct effects on Mϕ function.

The protective effect of enteric glial cells on intestinal epithelial barrier function is enhanced by inhibiting inducible nitric oxide synthase activity under lipopolysaccharide stimulation

Enteric glial cells (EGC) play an essential role in maintaining the integrity of intestinal epithelial barrier (IEB). However, the mechanism of EGCs in the regulation of IEB functions under lipopolysaccharide (LPS) stimulation is unknown. To investigate the barrier-related role of EGCs in response to the LPS challenge, the coculture model of EGCs and intestinal epithelial cells (IEC) IEC-6 was established in vitro. Transepithelial resistance (TER) measurements showed that, LPS treatment significantly increased barrier permeability of IEC monolayer from the basolateral side (35.4±6.3 Ω/cm(2), p<0.05) but not the apical side (69.7±6.3 Ω/cm(2)) when compared with the control group (81.8±10.9 Ω/cm(2)). The assessment of intestinal epithelial integrity by TER reading and by measuring expression of tight junction protein revealed that, incubation with EGCs or EGC conditioned media significantly increased the TER of IEC monolayers under normal condition as well as the LPS stimulation, accompanied with upregulating zonula occludens-1 and occludin expression at mRNA and protein levels. Real-time quantitative polymerase chain reaction and nitric production assay demonstrated that LPS exposure elicited a maximally 13-fold increase of inducible nitric oxide synthase (iNOS) mRNA expression and 10-fold increase of nitric oxide production of EGCs. After being pretreated with the selective iNOS inhibitor 1400 W, EGCs significantly increased the TER of IEC monolayers against the disruption effect of LPS (p<0.05). These findings suggest that EGCs play an important role in maintaining the IEB function in response to the LPS stimulation. The protective effect of EGCs on IEB functions could be enhanced by inhibiting the increase of iNOS activity induced by LPS.

The preliminary experimental and clinical study of the relationship between the pigment gallstone and intestinal mucosal barrier

AIMS

To investigate the relations between the formation of pigment gallstone and the function of the intestinal mucosal barrier, as well as the underlying mechanism.

METHODS

Eighty guinea pigs were randomly divided into three groups in which they were respectively given normal diet, gallstone-causing diet, and gallstone-formation diet with a supplementary intestinal mucosal protection compound known as glutamine. The model of pigment gallstone was established after 8 weeks of dietary administration. Indices about the function of the intestinal mucosal barrier and bacterial translocation were measured. Clinical cases were divided into three groups: control, cholesterol gallstone, and pigment gallstone, where the levels of plasma diamine oxidase (DAO), plasma endotoxin and the excretion rates of technetium 99m-diethylene triamine pentaacetic acid (99mTC-DTPA) in the urine of each group were measured.

RESULTS

In the pigment gallstone group, the level of plasma DAO and endotoxin, the excretory ratio of lactulose and mannitol in urine, the bacterial translocation ratio in the celiac lymph nodes and the activities of beta-glucuronidase increased comparing to the control group. The gallstone-formation rate for the intestinal mucosal protection group (GLN) decreased, and other indices, except the activity of beta-glucuronidase, were all lower than that of gallstone-formation group. In the clinical experiment, the levels of plasma DAO and endotoxin, as well as the excretory rate of 99mTC-DTPA in urine were higher in the patients with gallstones than that in the control group.

CONCLUSIONS

The formation of pigment gallstone was related to the abnormal function of the intestinal mucosal barrier. The abnormality in the function of the intestinal mucosal barrier probably induced the formation of gallstone by a bacterial translocation mechanism.

Effects of gut barrier dysfunction and NF-kappaB activation on aggravating mechanism of severe acute pancreatitis

OBJECTIVE

To study the effects of gut-derived endotoxin translocation and NF-kappaB activation on the aggravating mechanism of severe acute pancreatitis (SAP) and of treatment with pyrrolidine dithiocarbamate (PDTC) on rats with SAP.

METHODS

SD rats were randomly divided into sham operation group (SO), SAP group, SAP + lipopolysaccharide(LPS) group, pyrrolidine dithiocarbamate (PDTC) treatment group and LPS group. Biochemical parameters and cytokines were examined in the serum. Multiple organs pathological slices were examined. Expression of NF-kappaB mRNA in the liver tissue was detected by RT-PCR. Activation of NF-kappaB by the method of streptomycin avidin-peroxidase (SP) and expression of NF-kappaB p65 protein and its binding activity were analyzed by Western blot and electrophoretic mobidity shift assay (EMSA).

RESULTS

Compared with sham operation group, the concentration of TNF-alpha, alanine aminotransferase (ALT), and diamine oxidase (DAO) in serum significantly increased in SAP + LPS group (P < 0.05). Pathological changes were markedly observed in tissues and the expression of NF-kappaB mRNA in the liver significantly increased (P < 0.05) also, the activation of NF-kappaB and binding activity of NF-kappaB p65 protein in the liver markedly increased (P < 0.01) in SAP + LPS group. Treatment with PDTC markedly reduced concentration of ALT, DAO and TNF-alpha, and the expression of NF-kappaB, and the pathologic scores, as well as significantly decreased the expression of NF-kappaB p65 protein.

CONCLUSION

The activation and overexpression of NF-kappaB may participate in the aggravating mechanism of SAP. Treatment with PDTC has a protective effect on multiple organs damage in SAP.

Parenteral nutrition related hepato-biliary disease in adults

Parenteral nutrition is a life-saving therapy in patients with intestinal failure. One of the major causes of morbidity and mortality in patients receiving long-term total parenteral nutrition (TPN) is liver disease. Early on, there is steatosis, which can evolve to steatohepatitis and eventually to cholestasis of varying severity. The etiology of parenteral nutrition related liver disease is multifactorial. Provision of excess calories in the TPN solution, along with lipids administered >1 g/kg are thought to increase the risk of parenteral nutrition related liver disease. Other factors such as nutrient deficiencies and nutrient toxicities may also play a role in the pathogenesis of liver disease, along with sepsis and the lack of enteral stimulation. Non-pharmacological management strategies for TPN-related liver disease include enteral stimulation, optimal TPN composition, and avoidance of excess carbohydrate and lipid calories. Pharmacological therapy with ursodeoxycholic acid and antibiotic therapy to reduce the risk of bacterial translocation and sepsis should be considered. Early referral for transplantation should be considered in patients with evidence of portal hypertension. This review focuses on the clinical aspects, pathogenesis, and management strategies of parenteral nutrition-related liver disease in adult patients.

Total parenteral nutrition-related gastroenterological complications

Total parenteral nutrition is a life saving therapy for patients with chronic gastrointestinal failure, being an effective method for supplying energy and nutrients when oral or enteral feeding is impossible or contraindicated. Clinical epidemiological data indicate that total parenteral nutrition may be associated with a variety of problems. Herein we reviewed data on the gastroenterological tract regarding: (i) total parenteral nutrition-related hepatobiliary complications; and (ii) total parenteral nutrition-related intestinal complications. In the first group, complications may vary from mildly elevated liver enzyme values to steatosis, steatohepatitis, cholestasis, fibrosis and cirrhosis. In particular, total parenteral nutrition is considered to be an absolute risk factor for the development of biliary sludge and gallstones and is often associated with hepatic steatosis and intrahepatic cholestasis. In general, the incidence of total parenteral nutrition-related hepatobiliary complications has been reported to be very high, ranging from 20 to 75% in adults. All these hepatobiliary complications are more likely to occur after long-term total parenteral nutrition, but they seem to be less frequent, and/or less severe in patients who are also receiving oral feeding. In addition, end-stage liver disease has been described in approximately 15-20% of patients receiving prolonged total parenteral nutrition. Total parenteral nutrition-related intestinal complications have not yet been adequately defined and described. Epidemiological studies intended to define the incidence of these complications, are still ongoing. Recent papers confirm that in both animals and humans, total parenteral nutrition-related intestinal complications are induced by the lack of enteral stimulation and are characterised by changes in the structure and function of the gut. Preventive suggestions and therapies for both these gastroenterological complications are reviewed and reported in the present review.

Role of the urothelium in urinary bladder dysfunction following spinal cord injury

A consequence of spinal cord injury is a change in bladder reflex pathways resulting in the emergence of detrusor hyperreflexia and increased activity of the urethral sphincter. A basis for some of these alterations could be changes in the environment of bladder sensory nerve endings at the target organ. Recent evidence suggests that the urothelium (the lining of the urinary bladder) plays a prominent role in modulating bladder sensory nerve ending excitability. It is conceivable that factors and processes affecting the plasticity of bladder neurons after spinal cord injury may be partly due to changes occurring in the urothelium. Although the urothelium has classically been thought of as a passive barrier to ions/solutes, a number of novel properties have been recently attributed to these cells. Our work and that of others clearly demonstrates that the urothelium exhibits both "sensor" (expression of sensor molecules or response to thermal, mechanical and chemical stimuli) as well as "transducer" (release of factors/transmitters) properties. Taken together, these and other findings discussed in this chapter suggest a sensory function for the urothelium and that alterations in urothelial properties may contribute to afferent abnormalities following spinal cord injury.

Influence of intestinal barrier function on pigment gallstone formation in guinea pig model

AIM: To investigate the possible action and mechanism of the intestinal barrier function in the pathogenesis of pigment gallstone.

METHODS: Eighty guinea pigs were randomly divided into three groups: normal group (CON), pigment gallstone group (PS) and intestinal mucosa protection group (GLN). Normal forage, pigment gallstone-forming forage and pigment gallstone-forming forage with supplemental intestinal mucosa protector (glutamine) were given to the animals of corresponding groups, respectively. The gallstone-forming rate, morphological changes of intestinal mucosa, intestinal permeability, serum endotoxin and biliary β-glucuronidase were detected after 8 wk.

RESULTS: The gallstone-forming rate was 73.9% in PS. In comparison with those in CON, the intestinal mucosa damage, serum endotoxin level [(1367±525)×10^-6 EU/L vs (77±43) ×10^-6 EU/L, P < 0.01] and activity of biliary β-glucuronidase (endogenous: from 209.8±47.5 vs 122.1±39.5 Fishman Unit, P < 0.01; exogenous: from 2206.6±983.9 vs 573.5±476.9 Fishman Unit, P < 0.01) were significantly increased in PS. In GLN, the gallstone-forming rate was decreased to 44.4%, which was markedly higher than that in PS (P < 0.05). The morphological changes of intestinal mucosa, intestinal permeability and serum endotoxin [(156±97)×10^-6 EU/L vs (1367±525)×10^-6 EU/L, P < 0.05] were notably decreased in GLN as compared with those in PS, and there was no significant difference in β-glucuronidase activity.

CONCLUSION: Intestinal barrier function is correlated with pigment gallstone formation. Intestinal barrier function disorder may promote pigment gallstone formation through bacteria translocation, endotoxemia and change of biliary β-glucuronidase activity.

Stress induces the translocation of cutaneous and gastrointestinal microflora to secondary lymphoid organs of C57BL/6 mice

Mammals are colonized by a vast array of bacteria that reside as part of the host's microflora. Despite their enormous levels, these microorganisms tend to be restricted to cutaneous and mucosal surfaces. In the current experiment, only a small percentage of non-stressed mice exhibited detectable levels of bacteria in their inguinal lymph nodes (ILN), spleen, liver, or mesenteric lymph nodes (MLN). However, after experiencing repeated social disruption (SDR), a significant increase in the number of animals having bacteria in their ILN and MLN was found. Since SDR involves fighting in which bite wounds on the skin could provide a portal of entry into the host, it was determined whether experimental wounding (full-thickness skin biopsy), chronic restraint (which is a potent stressor that does not disrupt the skin barrier), or wounding combined with restraint would increase the occurrence of bacteria in secondary lymphoid tissues and liver. Wounding did not significantly increase the prevalence of bacteria in the ILN, MLN, or liver. Interestingly, a larger percentage of restrained and restrained plus wounded mice, in comparison to controls, had bacteria in the ILN, MLN, and liver. Although the stressors increased the number of animals that became colonized, the levels of bacteria in the stressed mice were similar to the levels found in the few non-stressed mice that did become colonized. Our results indicate that psychological components of social stress facilitate the translocation of indigenous bacteria into the host, thus identifying an additional facet through which stressors may impact health.

Suppressor of cytokine signaling-2 modulates the fibrogenic actions of GH and IGF-I in intestinal mesenchymal cells

Growth hormone (GH) and IGF-I play important roles in wound healing during intestinal injury and inflammation, but there is also indirect evidence that locally expressed IGF-I may act to induce excessive collagen deposition, which can lead to intestinal fibrosis. Factors that dictate the balance between normal wound healing and excessive healing responses are unknown. Using RNase protection assay and in situ hybridization, we determined whether GH and/or IGF-I increase type I collagen deposition in the intestine of rats fed by total parenteral nutrition (TPN), a feeding modality used for many patients following intestinal surgery and resection. We also used an in vitro model system to confirm our in vivo effects and to directly evaluate the relative potency of GH and IGF-I on DNA synthesis and collagen deposition in intestinal myofibroblasts. Both GH and IGF-I stimulated collagen production in vivo and in vitro, and IGF-I, but not GH, stimulated DNA synthesis in vitro. In collagen production, GH was less potent than IGF-I. Suppressors of cytokine signaling (SOC) are cytokine-inducible proteins that negatively feedback to inhibit the actions of cytokines and we recently found that GH selectively upregulates SOC-2 in the intestine of TPN-fed rats. We examined whether SOC-2 may be responsible for the difference in magnitude of action of GH and IGF-I on collagen accumulation. GH, but not IGF-I, induced SOC-2 in isolated myofibroblasts, and overexpression of SOC-2 led to a suppression of GH- and IGF-I-induced collagen accumulation. SOC-2 null mice infused with IGF-I showed greater collagen gene expression compared with wild-type (WT) mice. Myofibroblasts isolated from SOC-2 null mice showed increased IGF-I-stimulated DNA synthesis compared with WT cells. Taken together, these findings suggest that SOC-2 induced by GH may play an important role in suppressing collagen accumulation and mesenchymal cell proliferation induced by GH or GH-induced IGF-I, providing a mechanism for the differing potencies of GH and IGF-I on intestinal mesenchyme and collagen synthesis.