Tight Junction Gene Expression Research Articles

Exposure to concentrated ambient PM2.5 (CAPM) induces intestinal disturbance via inflammation and alternation of gut microbiome.

Air pollution causes a great disease burden worldwide. Recent evidences suggested that PM2.5 contributes to intestinal disease. The objective of present study was to investigate the influence of ambient PM2.5 on intestinal tissue and microbiome via whole-body inhalation exposure. The results showed that high levels and prolonged periods exposure to concentrated ambient PM2.5 (CAPM) could destroy the mucous layer of the colon, and significantly alter the mRNA expression of tight junction (Occludin and ZO-1) and inflammation-related (IL-6, IL-10 and IL-1β) genes in the colon, comparing with exposure to the filtered air (FA). The composition of intestinal microbiome at the phylum and genus levels also varied along with the exposure time and PM2.5 levels. At the phylum level, Bacteroidetes was greatly decreased, while Proteobacteria was increased after exposure to CAPM, comparing with exposure to FA. At the genus level, Clostridium XlVa, Akkermansia and Acetatifactor, were significantly elevated exposure to CAPM, comparing with exposure to FA. Our results also indicated that high levels and prolonged periods exposure to CAPM altered metabolic functional pathways. The correlation analysis showed that the intestinal inflammation was related to the alteration of gut microbiome induced by CAPM exposure, which may be a potential mechanism that elucidates PM2.5-induced intestinal diseases. These results extend our knowledge on the toxicology and health effects of ambient PM2.5.

Night-Restricted Feeding Improves Gut Health by Synchronizing Microbe-Driven Serotonin Rhythm and Eating Activity-Driven Body Temperature Oscillations in Growing Rabbits.

The circadian misalignment of the gut microbiota caused by unusual eating times in adult animals is related to disease development. However, whether the composition and diurnal rhythm of gut microbiota can be optimized by synchronizing the window period of eating with natural eating habits to reduce the risk of diarrhea remains unclear, especially in growing animals. In this study, 108 5-week-old weaned rabbits (nocturnal animals) were randomly subjected to daytime feeding (DF) and night-restricted feeding (NRF). At age 12 weeks, six rabbits were selected from each group, and caecum and cecal contents, as well as serum samples were collected at 4-h intervals during 24 h. Overall, NRF was found to reduce the risk of diarrhea in growing rabbits, improved the diurnal rhythm and abundance of beneficial microorganisms, along with the production of beneficial metabolites, whereas reduced the abundance of potential pathogens (Synergistes, Desulfovibrio, and Alistipes). Moreover, NRF improved diurnal rhythm of tryptophan hydroxylase isoform 1 and serotonin. Furthermore, NRF strengthened the diurnal amplitude of body core temperature, and promoted the diurnal expression of intestinal clock genes (BMAL1, CLOCK, REV-ERBα, and PER1), and genes related to the regulation of the intestinal barrier (CLAUDIN-1), and intestinal epithelial cell self-proliferation and renewal (BMI1). In vitro simulation experiments further revealed that synchronization of microbial-driven serotonin rhythm and eating activity-driven body temperature oscillations, which are important zeitgebers, could promote the diurnal expression of clock genes and CLAUDIN-1 in rabbit intestinal epithelial cells (RIEC), and enhance RIEC proliferation. This is the first study to reveal that NRF reprograms the diurnal rhythm of the gut microbiome, promotes the diurnal expression of clock genes and tight junction genes via synchronization of microbial-driven serotonin rhythm and eating activity-driven body temperature oscillations, thereby improving intestinal health and reducing the risk of diarrhea in growing rabbits. Collectively, these results provide a new perspective for the healthy feeding and management of growing animals.

The preventive effect and mechanisms of adsorbent supplementation in low concentration aflatoxin B1 contaminated diet on subclinical symptom and histological lesions of broilers

This study aimed to investigate the subclinical symptom and histological lesions of 21-day-old and 42-day-old broilers exposure to low concentration aflatoxin B1 (AFB1), and the preventive effect with adsorbent (Toxo-MX) supplementation. A total of 576 one-day-old Arbor Acres broilers were randomly allotted into 6 treatments 8 replicates and 12 birds per cage, fed with 0 ppb, 60 ppb and 120 ppb AFB1 contamination diet with or without Toxo-MX supplementation. Results showed both 60 ppb and 120 ppb AFB1 contamination significantly reduced growth performance in 21-day-old broilers (P < 0.05), but not in 42-day-old broilers (P > 0.05), however, AFB1 contamination in diet caused a higher feed to gain ratio (P < 0.05). Broilers of 21-day-old exposure to 60 ppb and 120 ppb AFB1 increased mRNA expression of hepatic inflammatory cytokines, and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activity (P < 0.05), 42-day-old broilers showed a same change in 120 ppb but not in 60 ppb of AFB1 contamination (P < 0.05). mRNA expressions of clauding-1, Zonula occludens-1 (ZO-1), and occludin decreased, but Bax, Bcl-2, and caspase-3 increased in 21-day-old broilers exposure to 60 ppb and 120 ppb AFB1 (P < 0.05), broilers of 42-day-old resisted on intestinal aflatoxicosis impairment against 60 ppb AFB1 contamination (P < 0.05), but not in 120 ppb (P < 0.05). Toxo-MX supplementation significantly reversed the detrimental effects on growth performance in both age broilers and reduced the accelerated feed to gain ratio caused by AFB1 (P < 0.05). Intestinal mRNA expression of tight junction and apoptotic genes in both age broilers were recovered by Toxo-MX supplementation (P < 0.05). However, Toxo-MX did not restore the accelerated expression of hepatic inflammation cytokines and SOD, GSH-Px in 120ppb AFB1 group (P < 0.05). The data demonstrated that diet supplementation with Toxo-MX reversed the detrimental effect on growth performance and intestine in broilers exposure to 60 ppb and 120 ppb AFB1. However, did not completely recovered hepatic inflammation induced by AFB1.

Thiamine modulates intestinal morphological structure and microbiota under subacute ruminal acidosis induced by a high-concentrate diet in Saanen goats

Ruminant animals are generally fed with starch-rich grain as the main energy source, and the incidence of metabolic diseases such as subacute ruminal acidosis (SARA) is high due to the intensive farming. Thiamin has been reported to alleviate SARA caused by high-concentrate diets, but the exact mechanism is not well understood. The goal of this study was to examine the role of thiamine in intestinal inflammation and microbiota caused by high-concentrate diets. The SARA model was induced by low neutral detergent fibre/starch ration to study the effects of thiamine on intestinal tissue structure and microbiota. 18 mid-lactation (148 ± 3 d in milk; milk yield = 0.71 ± 0.0300 kg/d) Saanen goats (BW = 36.5 ± 1.99 kg; body condition score = 2.73 ± 0.16, where 1 = emaciated and 6 = obese) in parities 1 or 2 were selected. The goats were randomly divided into three groups with six replicates: (1) control diet (C; concentrate:forage 30:70), (2) high-concentrate diet (H; concentrate:forage 70:30), and (3) high-concentrate diet with 200 mg of thiamine/kg of DM intake (H + T;concentrate:forage 70:30). The experimental period was lasted for 56 d. The small and large intestine, expression of inflammatory factor genes, tight junction protein genes, total antioxidant capacity, and intestinal microbiota were measured. The results showed that SARA was observed in treatment H, whereas rumen fluid pH was improved in treatment H + T. Treatment H + T also significantly repaired the intestinal tissue structure damaged by SARA, improved the total antioxidant capacity of the small intestinal mucosa, reduced mRNA expression of inflammatory factors in the small intestine tissue, and increased the mRNA expression of tight junction genes in small intestine tissue. The high-concentrate diet reduced the diversity of intestinal microbiota. When thiamine is added to the high-concentrate diet, the relative abundance of intestinal Firmicutes and beneficial bacteria represented by Lactobacilli were upregulated, and the relative abundance of Proteus, a marker of intestinal dysbacteriosis, returned to normal. In conclusion, thiamine supplementation could alleviate the damage to the intestinal tissue structure and microbial environment caused by SARA condition in dairy goats fed a high-concentrate diet.

Nutrient profile and effects of carinata meal as alternative feed ingredient on broiler performance, tight junction gene expression and intestinal morphology

Two studies were conducted to establish carinata meal as a partial replacement of conventional protein sources. Study I was conducted to determine the nutrient profile, nitrogen-corrected true metabolizable energy (TMEn), and amino acid (AA) digestibility of 2 groups: low glucosinolate carinata meal (LGCM) and high glucosinolate carinata meal (HGCM) using rooster assays. The LGCM contained 28 μmol/g glucosinolate, 11.5% moisture, 39.2% crude protein (CP), whereas the HGCM had 100 μmol/g glucosinolate, 10.1% moisture, 39.5% CP on as is basis. The precision-fed rooster assays were conducted to determine TMEn and AA digestibility. The TMEn levels of LGCM and HGCM were 1,814 and 1,690 kcal/kg on as is basis, respectively. Standardized digestibility for lysine, methionine, cysteine, threonine, and valine were 72, 88, 69, 75, and 79% for LGCM and 80, 89, 71, 76, and 80% for HGCM, respectively. Based on the nutrient profiles from study I, study II was conducted to evaluate the effects of LGCM and HGCM in broilers. A total of 504 one-day-old Cobb500 male broiler chickens were randomly divided into 42 battery cages with 6 replicates of 12 birds per cage. The seven dietary treatments were control diet, 3 inclusion levels of LGCM (4, 8, and 12%), and 3 of HGCM (4, 8, and12%) in a corn-SBM based diet fed for 21 d. No significant differences in BW, BWG, and FI were observed except for significantly lower BWG in 12% HGCM group compared to control for 14-21 days (P < 0.05). The FCR for 12% HGCM increased significantly compared to 4 and 8% of both LGCM and HGCM groups during wk 3 (14–21 d). Based on these studies, carinata meal could be recommended to partially replace conventional feed ingredients at a rate of 12% when LGCM is used and 8% when HGCM is used with no deleterious effects on growth performance, gut histology, and tight junction proteins.

Physiological and Psychological Effects of Treadmill Overtraining Implementation.

Simple SummaryOvertraining occurs when an imbalance between training stress and recovery exists, and it is prevalent in athletes, soldiers, physical education, and health education undergraduates as well as a number of female and male adolescents. Despite a broad body of evidence concerning physiological and psychological correlates of this syndrome, the pathomechanisms of overtraining are still poorly understood. This illustrates the need to establish animal models of this disorder. This article outlines and discusses physiological and psychological effects of the current established overtraining model, based on an eight-week exhaustive treadmill exercise that reveals the involvement of imbalanced energy expenditure, exacerbated inflammatory response, increased intestinal permeability, and anxiety status in the development and onset of overtraining. This study highlights the maladaptation of overtraining and provides an animal model to determine the effectiveness of possible strategies, including nutrition and monitoring, for treatment and prevention of overtraining syndromes in future studies.Overtraining in athletes usually causes profound and lasting deleterious effects on the maintenance of health and exercise capacity. Here, we established an overtraining animal model to investigate the physiological modulation for future strategic applications in vivo. We subjected C57BL/6 mice to exhaustive treadmill exercises daily for 8 weeks (the exhaustive exercise group). Next, the physiological and psychological outcomes were compared with the regular exercise and sedentary groups. Outcome measures included growth, glucose tolerance, exercise metabolism profiles, cytokine levels, intestinal tight junction gene expression, and psychological behavioral changes. Our results revealed that overtraining negatively affected the physiological and psychological changes in the current model. The exhaustive exercise group exhibited significantly lower endurance performance and imbalanced energy expenditure, causing a decrease in body fat mass and slowing down the growth curve. In addition, the inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, and interleukin-1β) and immune cells (neutrophils and monocytes) were significantly elevated after successive exhaustive exercise interventions. Furthermore, overtraining-induced stress resulted in increased anxiety status and decreased food intake. Our findings reinforce the idea that an imbalance between exercise and recovery can impair health and performance maintenance after overtraining. This study highlights the maladaptation of overtraining and provides an animal model to determine the effectiveness of possible strategies, including nutrition and monitoring, for treatment and prevention of overtraining syndromes in future studies.

Effect of Antarctic krill phospholipid (KOPL) on high fat diet-induced obesity in mice

Phospholipids are the main lipid components in Antarctic krill oil, and the combination of n-3 polyunsaturated fatty acids (n-3 PUFAs) shows multiple nutritional advantages. At present, the research about Antarctic krill phospholipid (KOPL) mainly focuses on the purification, and there are few reports on the anti-obesity effect. Thus, this study aimed at evaluating the effect of KOPL on the high-fat diet (HFD)-induced obesity mice. All the mice were divided into five groups, which were fed chow diet, HFD, and different doses of KOPL + HFD, respectively. The results showed that KOPL treatment could reduce the weight gain, fat accumulation, and liver tissue damage in HFD-induced mice. KOPL treatment could reduce the levels of serum lipid (TC, TG, L-LDL) and fasting blood glucose in HFD-induced mice, and the inflammatory cytokines (IL-1β and TNF-α) in serum. Further analysis showed that KOPL could promote the normal expression of lipid-synthesis-related genes and proteins, including sterol regulatory element-binding protein-1c (SREBP-1c), fatty acid synthetase (FAS), and peroxisome proliferator-activated receptor alpha (PPAR-α) in liver tissue. Besides, it inhibited the overexpression of inflammatory cytokine genes (IL-1β and TNF-α), but increased the expression of tight junction genes (ZO-1 and Occludin) in the colon tissue. Additionally, KOPL improved the decrease of diversity and imbalance of intestinal microbiota, which could contribute to its beneficial effects. In summary, the KOPL treatment improves the effects of HFD-induced obese mice by maintaining normal lipid levels, protecting the liver tissue, reducing inflammation response and intestinal damage, and regulating intestinal microbiota abnormalities. It refer to KOPL could be a promising dietary strategy for treating obesity and improving its related metabolic diseases.

Optimal liver metabolism and proliferation require the tight junction protein claudin-3

Abstract Objective The expression of hepatic tight junction proteins and their contribution to homeostasis and regeneration remained largely unexplored. Here, we determine the cell type specific expression of tight junction genes in murine livers. We further explore the regulation and functional importance of the transmembrane protein CLDN3 in normal and regenerating livers. Methods Murine livers were used for tissue- and single cell RNA-seq. CLDN3 localization was determined by immunofluorescence. CLDN3+/+ or CLDN3-/- livers were analysed by electron microscopy, fluorescence-activated cell sorting and liquid chromatography mass spectrometry. Lipid content was quantified with oil-red. Mice were subjected to 2/3 partial hepatectomy. Proliferation was quantified with Ki67 and pHH3 stainings. Cell cycle gene expression was determined by RT-qPCR. Barrier impairments were assessed with total bile acid measurements. Differential gene expression was analysed by tissue RNAseq with DESeq2. Results We determined the profile of tight junction gene expression the main liver cell types, showing that tight junction transcripts can be found in hepatocytes and cholangiocytes but also on non-parenchymal cell populations. CLDN3 was among the highly expressed- and regulated genes in native and regenerating livers. CLDN3 had a zonated expression pattern. CLDN3-/- mice had microscopically intact tight junctions, but showed significantly downregulated hepatic energy metabolism and suboptimal cell proliferation in the regeneration model. Conclusion Our data suggests a functional role of CLDN3 for maintenance of energy homeostasis and optimal regeneration, proving that the function of hepatic tight junction proteins extends beyond basic membrane sealing.

Effects of GLP-1 receptor agonist on changes in the gut bacterium and the underlying mechanisms

There is a close relationship between the gut microbiota and metabolic disorders. In this study, acute administration of the glucagon-like peptide-1 receptor agonist (GLP-1RA) liraglutide to mice increased the cecal levels of caseinolytic protease B, a component of Escherichia coli, and of norepinephrine. Chemical sympathectomy blocked these events. Norepinephrine was found to pass into the intestinal lumen in vitro. c-Fos staining of the intermediolateral nucleus was identified as indirect evidence of sympathetic nervous system activation of the intestinal tract by GLP-1RA. Under normal conditions, the increase in E. coli did not affect the host. However, in mice with colitis, bacterial translocation was observed with attenuation of tight junction gene expression. This is the first study to investigate the unique underlying mechanisms related the effects of GLP-1RA on changes in the gut bacterium.

Glutamine Administration Attenuates Kidney Inflammation in Obese Mice Complicated with Polymicrobial Sepsis.

Obesity is a well-known public health issue around the world. Sepsis is a lethal clinical syndrome that causes multiorgan failure. Obesity may aggravate inflammation in septic patients. Glutamine (GLN) is a nutrient with immune regulatory and anti-inflammatory properties. Since sepsis is a common contributing factor for acute kidney injury (AKI), this study investigated the effects of GLN administration on sepsis-induced inflammation and AKI in obese mice. A high-fat diet which consists of 60% of calories from fat was provided for 10 weeks to induce obesity in the mice. Then, the obese mice were subdivided into sepsis with saline (SS) or GLN (SG) groups. Cecal ligation and puncture (CLP) was performed to produce sepsis. The SS group was intravenously injected with saline while the SG group was administered GLN one or two doses after CLP. Obese mice with sepsis were sacrificed at 12, 24, or 48 h post-CLP. Results revealed that sepsis resulted in upregulated high-mobility group box protein-1 pathway-associated gene expression in obese mice. Also, expressions of macrophage/neutrophil infiltration markers and inflammatory cytokines in kidneys were elevated. Obese mice treated with GLN after sepsis reversed the depletion of plasma GLN, reduced production of lipid peroxides, and downregulated macrophage/neutrophil infiltration and the inflammatory-associated pathway whereas tight junction gene expression increased in the kidneys. These findings suggest that intravenously administered GLN to obese mice after sepsis alleviated inflammation and attenuated AKI. This model may have clinical application to obese patients with a risk for infection in abdominal surgery.

The effect of Astragalus polysaccharide on growth, gut and liver health, and anti-viral immunity of zebrafish

Our study aimed to investigate the effect of dietary Astragalus polysaccharide (APS) on growth performance, gut and liver health and anti-viral capability of zebrafish. Zebrafish were fed control diet and the experimental diets containing 0.01% or 0.02% APS for three weeks. Growth performance, gut health parameters such as expression of inflammatory and tight junction genes, antioxidant capability, and microbiota composition were detected after three weeks feeding. Liver health was evaluated by serum ALT and AST levels, as well as expression of genes realated to inflammation and lipid metabolism. Zebrafish were challenged by SVCV at the end of feeding. The antiviral immune response was evaluated at 4 days post SVCV infection and survival rate was calculated 14 days after challenge. The results showed that 0.01% and 0.02% APS supplementation increased weight gain and decreased the FCR of zebrafish (P < 0.05). The intestinal expression of anti-inflammatory cytokine IL-10, tight junction protein 1b, and Occludin1 was significantly up-regulated in 0.01% APS group compared with control (P < 0.05). Furthermore, 0.01% APS decreased the content of MDA and increased total antioxidant capacity in zebrafish intestine, and the relative expression of SOD, GST and Gpxa were improved. Total bacteria and the abundance of Fusobacteria and Firmicutes in the intestinal microbiota was increased in 0.01% and 0.02% APS groups compared with control (P < 0.05). Zebrafish fed 0.01% APS showed higher survival rate after SVCV challenge. Accordingly, the expression of antiviral genes in the spleen was increased at 4 days post infection. In contrast to 0.01% supplementation, 0.02% APS compromised liver health, and exerted no positive effects on antiviral immunity. In conclusion, our results indicate that dietary 0.01% APS supplementation can improve growth performance, gut health and antiviral immunity of zebrafish, while 0.02% APS compromised liver health.

Loss of Claudin-3 Impairs Hepatic Metabolism, Biliary Barrier Function, and Cell Proliferation in the Murine Liver.

Background & AimsTight junctions in the liver are essential to maintain the blood-biliary barrier, however, the functional contribution of individual tight junction proteins to barrier and metabolic homeostasis remains largely unexplored. Here, we describe the cell type–specific expression of tight junction genes in the murine liver, and explore the regulation and functional importance of the transmembrane protein claudin-3 in liver metabolism, barrier function, and cell proliferation.MethodsThe cell type–specific expression of hepatic tight junction genes is described using our mouse liver single-cell sequencing data set. Differential gene expression in Cldn3-/- and Cldn3+/+ livers was assessed in young and aged mice by RNA sequencing (RNA-seq), and hepatic tissue was analyzed for lipid content and bile acid composition. A surgical model of partial hepatectomy was used to induce liver cell proliferation.ResultsClaudin-3 is a highly expressed tight junction protein found in the liver and is expressed predominantly in hepatocytes and cholangiocytes. The histology of Cldn3-/- livers showed no overt phenotype, and the canalicular tight junctions appeared intact. Nevertheless, by RNA-seq we detected a down-regulation of metabolic pathways in the livers of Cldn3-/- young and aged mice, as well as a decrease in lipid content and a weakened biliary barrier for primary bile acids, such as taurocholic acid, taurochenodeoxycholic acid, and taurine-conjugated muricholic acid. Coinciding with defects in the biliary barrier and lower lipid metabolism, there was a diminished hepatocyte proliferative response in Cldn3-/- mice after partial hepatectomy.ConclusionsOur data show that, in the liver, claudin-3 is necessary to maintain metabolic homeostasis, retention of bile acids, and optimal hepatocyte proliferation during liver regeneration. The RNA-seq data set can be accessed at: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE159914.

In Vivo Transplantation of Human Intestinal Organoids Enhances Select Tight Junction Gene Expression

BackgroundShort bowel syndrome is a potentially fatal condition with inadequate management options. Tissue-engineered small intestine (TESI) is a promising solution, but confirmation of TESI function will be crucial before human application. We sought to define intestinal epithelial barrier function in human intestinal organoid (HIO)-derived TESI. Materials and methodsHIOs were generated in vitro from human embryonic stem cells. After 1 mo, HIOs were collected for analysis or transplanted into the kidney capsule of immunocompromised mice. Transplanted HIOs (tHIOs) were harvested for analysis at 4 or 8 wk. Reverse transcription quantitative polymerase chain reaction and immunofluorescent staining were performed for tight junction components: claudin 3 (CLDN3), claudin 15 (CLDN15), occludin (OCLN), and zonula occludens-1, or tight junction protein-1 (TJP1/ZO-1). ResultsFour-week-old tHIOs demonstrated significantly (P < 0.05) higher levels of CLDN15 (6x), OCLN (4x), and TJP1/ZO-1 (3x) normalized to GAPDH than in vitro HIOs. Eight-week-old tHIOs demonstrated significantly (P < 0.05) higher expression levels of CLDN3 (26x), CLDN15 (29x), OCLN (4x), and TJP1/ZO-1 (5x) than in vitro HIOs. There was no significant difference in expression of these tight junction components between 4- and 8-week-old tHIOs. Immunofluorescent staining revealed the presence of claudin 3, claudin 15, occludin, and zonula occludens-1 in both in vitro HIOs and tHIOs; however, the morphology appeared more mature in tHIOs. ConclusionsIn vitro HIOs have lower levels of tight junction mRNA, and tight junction proteins appear morphologically immature. Transplantation facilitates maturation of the HIOs and enhances select tight junction gene expression.

Interstitial flow regulates in vitro three-dimensional self-organized brain micro-vessels

Cell culture under medium flow has been shown to favor human brain microvascular endothelial cells function and maturation. Here a three-dimensional in vitro model of the human brain microvasculature, comprising brain microvascular endothelial cells but also astrocytes, pericytes and a collagen type I microfiber – fibrin based matrix, was cultured under continuous medium flow in a pressure driven microphysiological system (10 kPa, in 60–30 s cycles). The cells self-organized in micro-vessels perpendicular to the shear flow. Comparison with static culture showed that the resulting interstitial flow enhanced a more defined micro-vasculature network, with slightly more numerous lumens, and a higher expression of transporters, carriers and tight junction genes and proteins, essential to the blood-brain barrier functions.

Maintaining intestinal structural integrity is a potential protective mechanism against inflammation in goose fatty liver

Overfeeding causes severe steatosis but not inflammation in goose liver, suggesting existence of protective components. Previous studies have shown that some intestinal microbes and their metabolites damage intestinal structural integrity and function, thus causing inflammation in the development of human and mouse nonalcoholic fatty liver disease. Therefore, this study hypothesizes that intestinal structural integrity of goose is maintained during overfeeding, which may provide goose fatty liver a protective mechanism against inflammation. To test this hypothesis, 48 seventy-day-old healthy Landes male geese were overfed (as overfeeding group) or normally fed (as control group). Blood and intestine (jejunum, ileum, and cecum) samples were harvested on the 12th and 24th d of overfeeding. Data showed that goose fatty liver was successfully induced by 24 d of overfeeding. Hematoxylin-eosin staining analysis indicated that the arrangement of villi and crypts in the intestine was orderly, and the intestinal structure was intact with no pathological symptoms in the 2 groups. Enzyme-linked immunosorbent assay and quantitative PCR analysis indicated no significant differences in the expression of tight junction and inflammation-related genes as well as plasma lipopolysaccharide concentration between the groups. Ileal hypertrophy and cecal atrophy were observed in the overfed vs. control geese, probably because of change of sphingolipid metabolism. Activation of apoptotic pathway may help cecum avoid necrosis-induced inflammation. In conclusion, healthy and intact intestine provides a layer of protection for goose fatty liver against inflammation. Sphingolipid metabolism may be involved in the adaptation of ileum and cecum to overfeeding. The hypertrophy of ileum makes it an important contributor to the development of goose fatty liver. The atrophy and decline in the function of cecum may be caused by apoptosis induced by overfeeding.

Effect of Perfluorooctanoic Acid on the Epigenetic and Tight Junction Genes of the Mouse Intestine.

Perfluorooctanoic acid (PFOA) has been implicated in various toxicities including neurotoxicity, genotoxicity, nephrotoxicity, epigenetic toxicity, immunotoxicity, reproductive toxicity, and hepatotoxicity. However, information on the accumulation of PFOA in the intestine and its toxic effects on intestinal epigenetics and tight junction (TJ) genes is sparse. CD1 mice were dosed with PFOA (1, 5, 10, or 20 mg/kg/day) for 10 days, and its accumulation and induced alterations in the expression of epigenetic and tight junction genes in the small intestine and colon were evaluated using LC–MS and qPCR techniques. PFOA reduced the expression levels of DNA methyltransferases (Dnmt1, Dnmt3a, Dnmt3b) primarily in the small intestine whereas, in the colon, a decrease was observed only at high concentrations. Moreover, ten-eleven translocation genes (Tet2 and Tet3) expression was dysregulated in the small intestine, whereas in the colon Tets remained unaffected. The tight junction genes Claudins (Cldn), Occludin (Ocln), and Tight Junction Protein (Tjp) were also heavily altered in the small intestine. TJs responded differently across the gut, in proportion to PFOA dosing. Our study reveals that PFOA triggers DNA methylation changes and alters the expression of genes essential for maintaining the physical barrier of intestine, with more profound effects in the small intestine compared to the colon.

Riemerella anatipestifer infection affects intestinal barrier structure and immune reactions in the duck caecum

ABSTRACT Riemerella anatipestifer (RA) infection causes high mortality and poor feed conversion, leading to great economic losses to the duck industry. This study investigated the effects of RA on the intestinal morphology and immune response of ducks. Histological examination showed that RA infection caused intestinal injury, including significantly reduced mucosal thickness on days 2, 3 and 5, significantly reduced villus height on days 1, 2, 3 and 5 (P < 0.05) and significantly reduced villus height to crypt depth ratios on days 2, 3, 5 and 9 of RA infection (P < 0.05). The expression of intestinal mucosal layer construction-associated genes and tight junction genes was significantly altered on at least one time point (day 1, 2, 3, 5, 9 or 14) after RA infection. Quantitative real-time polymerase chain reaction revealed that RA infection affected intestinal mucosal immune function. The genes encoding TLR4 (toll like receptor-4), TRAF6 (TNF receptor-associated factor 6), MYD88 (myeloid differentiation factor 88), IFN-γ (interferon-γ), IL (interleukin)-4 and IL-8 were significantly upregulated on day 2 of RA infection. Taken together, these results indicate that RA infection negatively affects intestinal barrier function in ducks due to impaired mucosal and villus-crypt structure and alters the mRNA expression of mucous layer construction-, intestinal tight junction-, and intestinal mucosal immunity-related genes.

Impact of chronic exposure to the ionic liquid ([C8mim][PF6]) on intestinal physical barrier, immunological barrier and gut microbiota in common carp (Cyprinus carpio L.)

Ionic liquids (ILs) are commonly known as "green" solvents and have been widely used in various fields. However, the ecotoxicity of ILs in aquatic environment has received considerable attention from scientific researchers. This study investigated the toxic effects of different concentrations of 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) (0, 1.35, 2.70 and 5.40 mg/L) on intestinal physical barrier, immunological barrier, and intestinal microbiome in common carp on days 30 and 60. The results showed that ([C8mim][PF6]) exposure could reduce the intestinal villus height, decrease the mRNA expression of tight junction genes (occludin, claudin-2 and zonula occludens-1), and increase the levels of D-lactic and diamine oxidase, and reduce acid phosphatase and lysozyme activities, complement 3 and 4 contents, and anti-inflammatory cytokine TGF-β protein level, while increase pro-inflammatory cytokines TNF-α and IL-1β protein levels in common carp. Moreover, ([C8mim][PF6]) exposure was also found to significantly reduce gut microbial diversity and alter microbial community structure in common carp. Collectively, our study highlighted that exposure to ([C8mim][PF6]) could disrupt intestinal physical barrier, impair immunological barrier and alter intestinal microbiome in common carp, suggesting that ILs exert a negative effect on fish intestinal health status and may pose serious health risks in fish. The results of this study may be helpful to illuminate the toxicity mechanisms of the ILs on fish.

Effect of phytase on nutrient digestibility and expression of intestinal tight junction and nutrient transporter genes in pigs.

The study was conducted to determine the effects of high levels of phytase on growth performance, nutrient digestibility, phytate breakdown, and expression of mucosal tight junction and nutrient transporter genes in weanling pigs. A total of 128 barrows were penned in groups of four and used in a randomized completely block design and assigned to four treatments for a 28-d study. A two-phase feeding was implemented (phase 1: day 1 to 14; phase 2: day 15 to 28). The diets differed in dietary calcium (Ca) and phosphorus (P) levels (positive control [PC]: 8.1 to 7.1 g/kg Ca and 6.5 to 6.8 g/kg P; negative control [NC]: 6.6 to 5.5 g/kg Ca and 5.6 to 5.3 g/kg P) from phase 1 to phase 2, respectively. NC diets were supplemented with phytase at 0 (NC), 1,500 (NC + 1,500), or 3,000 (NC + 3,000) phytase units (FTU)/kg. Blood was collected after fasting (day 27) or feeding (day 28) for the measurement of plasma inositol concentrations. On day 28, two pigs per pen were euthanized. Duodenal-jejunal and ileal digesta samples and feces were collected to determine inositol phosphates (InsP3-6) concentrations. Phytase supplementation increased the body weight on days 14 and 28 (P < 0.05). Average daily gain and feed efficiency compared with NC were increased by phytase with the majority of its effect in phase 1 (P < 0.05). The apparent ileal digestibility and apparent total tract digestibility of P were increased in piglets fed phytase-supplemented diets (P < 0.01) compared with NC piglets. Disappearance of InsP6 and total InsP3-6 up to the duodenum-jejunum, ileum, and in feces was increased by both phytase application rates (P < 0.01). Plasma concentrations of myo-inositol were higher (P < 0.001) in the phytase-supplemented diets than PC and NC diets, irrespective of whether pigs were fed or fasted. Expression of claudin 3 was higher in pigs fed both phytase-supplemented diets in the duodenum and jejunum compared with PC and NC. Mucin 2 expression was lower in the ileum of NC + 3,000 fed piglets compared with PC (P < 0.05), whereas expression of GLUT2 (solute carrier family 2-facilitated glucose transporter member 2) was increased (P < 0.05) by the NC + 3,000 treatment in all sections. In summary, high phytase supplementation increased the growth performance of nursery pigs. The increased expression of GLUT2 by phytase may indicate an upregulation of glucose absorption from the intestine by phytase.

Effects of Toxoplasma gondii infection on the function and integrity of human cerebrovascular endothelial cells and the influence of verapamil treatment in vitro

Toxoplasma gondii can cause parasitic encephalitis, a life-threatening infection that predominately occurs in immunocompromised individuals. T. gondii has the ability to invade the brain, but the mechanisms by which this parasite crosses the blood–brain-barrier (BBB) remain incompletely understood. The present study reports the changes associated with infection and replication of T. gondii within human brain microvascular endothelial cells (BMECs) in vitro. Our results indicated that exposure to T. gondii had an adverse impact on the function and integrity of the BMECs – through induction of cell cycle arrest, disruption of the BMEC barrier integrity, reduction of cellular viability and vitality, depolarization of the mitochondrial membrane potential, increase of the DNA fragmentation, and alteration of the expression of immune response and tight junction genes. The calcium channel/P-glycoprotein transporter inhibitor verapamil was effective in inhibiting T. gondii crossing the BMECs in a dose-dependent manner. The present study showed that T. gondii can compromise several functions of BMECs and demonstrated the ability of verapamil to inhibit T. gondii crossing of the BMECs in vitro.