Intestinal Barrier Permeability Research Articles

Lactiplantibacillus plantarum 124 Modulates Sleep Deprivation-Associated Markers of Intestinal Barrier Dysfunction in Mice in Conjunction with the Regulation of Gut Microbiota.

Intestinal diseases caused by sleep deprivation (SD) are severe public health threats worldwide. However, whether or not probiotics attenuate the intestinal damage associated with SD remains unclear. In this study, we used antibiotic pretreatment and fecal microbiota transplantation to investigate the protective role of Lactiplantibacillus plantarum (L. plantarum) 124 against SD-related intestinal barrier damage in C57BL/6 mice. Compared with those of a normal sleeping mouse, we observed that intestinal antioxidant capacity and anti-inflammatory cytokine levels were decreased, while pro-inflammatory cytokines were increased in sleep deprivation mice with an increasing duration of sleep deprivation. This resulted in decreased tight junction protein expression and increased intestinal barrier permeability. In contrast, intragastric administration with L. plantarum 124 reversed SD-associated intestinal oxidative stress, inflammation, colonic barrier damage, and the dysbiosis of the microbiota in the colon. In addition, L. plantarum 124 restored gut microbiota homeostasis via restoring abundance, including that of Dubosiella, Faecalibaculum, Bacillus, Lachnoclostridium, and Bifidobacterium. Further studies showed that gut microbiota mediated SD-associated intestinal damage and the treatment L. plantarum 124 in SD-associated colonic barrier damage. L. plantarum 124 is a potential candidate for alleviating SD-associated intestinal barrier damage. Overall, L. plantarum 124 consumption attenuates intestinal oxidative stress, inflammation, and intestinal barrier damage in SD-associated mice via the modulation of gut microbes.

Gut-derived 4-hydroxyphenylacetic acid attenuates sepsis-induced acute kidney injury by upregulating ARC to inhibit necroptosis

BackgroundStudies have found that the plasma content of gut-derived 4-hydroxyphenylacetic acid (4-HPA) was significantly increased in septic patients. However, the mechanism of 4-HPA elevation during sepsis and its relationship with sepsis-induced acute kidney injury (SAKI) remain unclear. MethodsCecal ligation and puncture (CLP) was performed in C57BL/6 mice to establish the SAKI animal model. Human renal tubular epithelial (HK-2) cells stimulated with lipopolysaccharide were used to establish the SAKI cell model. The widely targeted metabolomics was applied to analyze the renal metabolite changes after CLP. Proteomics was used to explore potential target proteins regulated by 4-HPA. The blood sample of clinical sepsis patients was collected to examine the 4-HPA content. ResultsWe found that renal gut-derived 4-HPA levels were significantly increased after CLP. The high permeability of intestinal barrier after sepsis contributed to the dramatic increase of renal 4-HPA. Intriguingly, we demonstrated that exogenous 4-HPA administration could further significantly reduce CLP-induced increases in serum creatinine, urea nitrogen, and cystatin C, inhibit renal pathological damage and apoptosis, and improve the survival of mice. Mechanistically, 4-HPA inhibited necroptosis in renal tubular epithelial cells by upregulating the protein expression of apoptosis repressor with caspase recruitment domain (ARC) and enhancing the interaction between ARC and receptor-interacting protein kinase 1 (RIPK1). ConclusionsThe increase of gut-derived 4-HPA in the kidney after sepsis could play a protective effect in SAKI by upregulating ARC to inhibit necroptosis.

Mannan oligosaccharides selenium ameliorates intestinal mucosal barrier, and regulate intestinal microbiota to prevent Enterotoxigenic Escherichia coli -induced diarrhea in weaned piglets

Enterotoxigenic Escherichia coli (ETEC) is a common diarrheal pathogen in humans and animals. To prevent and treat ETEC induced diarrhea, we synthesized mannan oligosaccharide selenium (MOSS) and studied its beneficial effect on ETEC-induced diarrhea. A total of 32 healthy weaned piglets (6.69 ± 0.01 kg) were randomly divided into four groups: NC group (Basal diet), MOSS group (0.4 mg/kg MOSS supplemented diet), MOET group (0.4 mg/kg MOSS supplemented diet + ETEC treatment), ETEC group (ETEC treatment). NC and ETEC group fed with basal diet, MOSS and MOET group fed with the MOSS supplemented diet. On the 8th and 15th day of the experiment, MOET and ETEC group were gavaged with ETEC, and NC and MOSS group were gavaged with stroke-physiological saline solution. Our data showed that dietary MOSS supplementation increased average daily gain (ADG) and average daily feed intake (ADFI) and significantly decreased diarrhea index and frequency in ETEC-treated piglets. MOSS did not affect the α diversity and β diversity of ileal microbial community, but it significantly decreased the proportion of lipopolysaccharide biosynthesis in ileal microbial community. MOSS supplementation regulated colonic microbiota community composition, which significantly increased carbohydrate metabolism, and inhibited lipopolysaccharide biosynthesis pathway in colonic microbial community. Moreover, MOSS significantly decreased inflammatory stress, and oxidative stress in ETEC treated piglets. Furthermore, dietary MOSS supplementation significantly decreased intestinal barrier permeability, and alleviated ETEC induced intestinal mucosa barrier irritation. In conclusion, our study showed that dietary MOSS supplementation ameliorated intestinal mucosa barrier, and regulated intestinal microbiota to prevent ETEC induced diarrhea in weaned piglets.

Age-associated decline in RAB-10 efficacy impairs intestinal barrier integrity.

The age-related decline in the ability of the intestinal barrier to maintain selective permeability can lead to various physiological disturbances. Adherens junctions play a vital role in regulating intestinal permeability, and their proper assembly is contingent upon endocytic recycling. However, how aging affects the recycling efficiency and, consequently, the integrity of adherens junctions remains unclear. Here we show that RAB-10/Rab10 functionality is reduced during senescence, leading to impaired adherens junctions in the Caenorhabditis elegans intestine. Mechanistic analysis reveals that SDPN-1/PACSINs is upregulated in aging animals, suppressing RAB-10 activation by competing with DENN-4/GEF. Consistently, SDPN-1 knockdown alleviates age-related abnormalities in adherens junction integrity and intestinal barrier permeability. Of note, the inhibitory effect of SDPN-1 on RAB-10 requires KGB-1/JUN kinase, which presumably enhances the potency of SDPN-1 by altering its oligomerization state. Together, by examining age-associated changes in endocytic recycling, our study sheds light on how aging can impact intestinal barrier permeability.

Dysfunction of the intestinal physical barrier in the intestinal inflammation of tongue sole, Cynoglossus semilaevis, induced by Shewanella algae infection

Bacterial intestinal inflammation occurs frequently in cultured fish. However, research on the dysfunction of the intestinal physical barrier in fish intestinal inflammation is scarce. In this study, intestinal inflammation in tongue sole Cynoglossus semilaevis was induced by Shewanella algae and the intestinal permeability was investigated. Gene expression patterns in inflammatory factors, tight junction molecules, and keratins 8 and 18 in the intestines were further explored. Histological examinations of the middle intestines showed that S. algae induced pathological lesions of intestinal inflammation and significantly increased the total number of mucous cells (p < 0.01). Ultrastructural observation in the middle intestines showed that intercellular spaces between epithelial cells were significantly wider in infected fish compared with the control (p < 0.01). The positive result of fluorescence in situ hybridization confirmed the presence of S. algae in the intestine. Enhanced Evans blue exudation and increased levels of serum d-lactate and intestinal fatty acid binding protein were suggestive of increased intestinal barrier permeability. The mRNA levels of four pro-inflammatory cytokines, namely IL-6, IL-8, IL-β, and TNF-α, were significantly increased after S. algae infection at most tested time points (p < 0.01 or p < 0.05), while there was an alternating increasing and decreasing trend in the gene expression patterns of IL-10, TGF-β, TLR-2, AP-1, and CASP-1. The mRNA expression of tight junction molecules (claudin-1, claudin-2, ZO-1, JAM-A, and MarvelD3) and keratins 8 and 18 in the intestines was significantly decreased at 6, 12, 24, 48, or 72 h post infection (p < 0.01 or p < 0.05). In conclusion, S. algae infection induced intestinal inflammation accompanied by increased intestinal permeability in tongue sole, and tight junction molecules and keratins were probably associated with the pathological process.

Diet high in linoleic acid dysregulates the intestinal endocannabinoid system and increases susceptibility to colitis in Mice

ABSTRACT Inflammatory bowel disease (IBD) is a multifactorial disease with increasing incidence in the U.S. suggesting that environmental factors, including diet, are involved. It has been suggested that excessive consumption of linoleic acid (LA, C18:2 omega-6), which must be obtained from the diet, may promote the development of IBD in humans. To demonstrate a causal link between LA and IBD, we show that a high fat diet (HFD) based on soybean oil (SO), which is comprised of ~55% LA, increases susceptibility to colitis in several models, including IBD-susceptible IL10 knockout mice. This effect was not observed with low-LA HFDs derived from genetically modified soybean oil or olive oil. The conventional SO HFD causes classical IBD symptoms including immune dysfunction, increased intestinal epithelial barrier permeability, and disruption of the balance of isoforms from the IBD susceptibility gene Hepatocyte Nuclear Factor 4α (HNF4α). The SO HFD causes gut dysbiosis, including increased abundance of an endogenous adherent invasive Escherichia coli (AIEC), which can use LA as a carbon source. Metabolomic analysis shows that in the mouse gut, even in the absence of bacteria, the presence of soybean oil increases levels of LA, oxylipins and prostaglandins. Many compounds in the endocannabinoid system, which are protective against IBD, are decreased by SO both in vivo and in vitro. These results indicate that a high LA diet increases susceptibility to colitis via microbial and host-initiated pathways involving alterations in the balance of bioactive metabolites of omega-6 and omega-3 polyunsaturated fatty acids, as well as HNF4α isoforms.

Gut dysbiosis-derived low-grade endotoxemia: A common basis for liver and cardiovascular disease.

Gut dysbiosis is characterized by bacteria overgrowth that ultimately leads to increased intestinal barrier permeability and translocation of bacteria or bacterial products such as lipopolysaccharide (LPS) in the portal and, eventually, systemic circulation. Intestinal epithelial cells and hepatocytes possess enzymatic armamentarium to counteract the LPS toxic effect, however, impaired degradation results in LPS accumulation in the hepatocytes and endothelial wall. Experimental and clinical studies documented that in patients with liver disease, such as nonalcoholic fatty acid liver disease (NAFLD), low-grade endotoxemia caused by LPS is implicated in liver inflammation and thrombosis via interaction with its Toll-like receptor 4 (TLR4) expressed by hepatocytes and platelets. Furthermore, studies in patients with severe atherosclerosis documented that LPS localizes in atherosclerotic plaque in close association with activated macrophages expressing TLR4 suggesting LPS's role in vascular inflammation, atherosclerotic progression, and thrombosis. Finally, LPS may directly interact with myocardial cells to induce electric and functional changes leading to atrial fibrillation or heart failure. This review will focus on experimental and clinical evidence suggesting that low-grade endotoxemia, as a mechanism, potentially accounts for vascular damage occurring at the level of the hepatic and systemic circulation and myocardial cells.

Hydroethanolic Extract of Fritillariae thunbergii Bulbus Alleviates Dextran Sulfate Sodium-Induced Ulcerative Colitis by Enhancing Intestinal Barrier Integrity.

The incidence of ulcerative colitis (UC), an inflammatory disorder of the gastrointestinal tract, has rapidly increased in Asian countries over several decades. To overcome the limitations of conventional drug therapies, including biologics for UC management, the development of herbal medicine-derived products has received continuous attention. In this study, we evaluated the beneficial effects of a hydroethanolic extract of Fritillariae thunbergii Bulbus (FTB) in a mouse model of DSS-induced UC. The DSS treatment successfully induced severe colonic inflammation and ulceration. However, the severity of colitis was reduced by the oral administration of FTB. Histopathological examination showed that FTB alleviated the infiltration of inflammatory cells (e.g., neutrophils and macrophages), damage to epithelial and goblet cells in the colonic mucosal layer, and fibrotic lesions. Additionally, FTB markedly reduced the gene expression of proinflammatory cytokines and extracellular matrix remodeling. Immunohistochemical analysis showed that FTB alleviated the decrease in occludin and zonula occludens-1 expression induced by DSS. In a Caco-2 monolayer system, FTB treatment improved intestinal barrier permeability in a dose-dependent manner and increased tight junction expression. Overall, FTB has potential as a therapeutic agent through the improvement of tissue damage and inflammation severity through the modulation of intestinal barrier integrity.

Effects of Yogurt with Carao (Cassia grandis) on Intestinal Barrier Dysfunction, α-glycosidase Activity, Lipase Activity, Hypoglycemic Effect, and Antioxidant Activity

Cell inflammation disrupts intestinal barrier functions and may cause disorders related to a leaky gut, possibly leading to diabetes. The objective of this study was to determine if carao (Cassia grandis) incorporated into yogurt enhances in vitro intestinal barrier function. To achieve this goal, Caco-2 cells were used as a model of intestinal barrier permeability. Caco-2 cells were treated with cytokines (interleukin-1β, tumor necrosis factor-α, interferon-γ, and lipopolysaccharide (LPS)) and yogurt with carao yogurt (CY) at different doses (1.3 g/L, 2.65 g/L, and 5.3 g/L). Real-time quantitative polymerase chain and immunofluorescence microscopy were applied to evaluate the expression and localization of tight junction proteins. Functional effects of the formulation of yogurt supplemented with carao were also evaluated in terms of the antioxidant activity, the α-glycosidase activity, and lipase inhibitory properties. In addition, the hypoglycemic potential was validated in vivo in a rat model. Compared to the control yogurt, Caco-2 TEER (transepithelial electrical resistance evaluation) by yogurt with 5.3 g/L of carao was significantly lower (p &lt; 0.05) after 48 h. Yogurt with 5.3 g/L of carao had a considerably lower permeability (p &lt; 0.05) than control yogurt in FD and LY flux. Yogurt with 5.3 g/L of carao enhanced the localization of ZO-1. Carao addition into yogurt increased the flavonoid content, apparent viscosity, lipase inhibition activity, and α-glycosidase activity. The rats fed with the yogurt with 5.3 g/L of carao demonstrated a higher blood glucose modulation.

The pathogenesis of gut microbiota in hepatic encephalopathy by the gut-liver-brain axis.

Hepatic encephalopathy (HE) is a neurological disease occurring in patients with hepatic insufficiency and/or portal-systemic blood shunting based on cirrhosis. The pathogenesis is not completely clear till now, but it is believed that hyperammonemia is the core of HE. Hyperammonemia caused by increased sources of ammonia and decreased metabolism further causes mental problems through the gut-liver-brain axis. The vagal pathway also plays a bidirectional role in the axis. Intestinal microorganisms play an important role in the pathogenesis of HE through the gut-liver-brain axis. With the progression of cirrhosis to HE, intestinal microbial composition changes gradually. It shows the decrease of potential beneficial taxa and the overgrowth of potential pathogenic taxa. Changes in gut microbiota may lead to a variety of effects, such as reduced production of short-chain fatty acids (SCFAs), reduced production of bile acids, increased intestinal barrier permeability, and bacterial translocation. The treatment aim of HE is to decrease intestinal ammonia production and intestinal absorption of ammonia. Prebiotics, probiotics, antibiotics, and fecal microbiota transplantation (FMT) can be used to manipulate the gut microbiome to improve hyperammonemia and endotoxemia. Especially the application of FMT, it has become a new treated approach to target microbial composition and function. Therefore, restoring intestinal microbial homeostasis can improve the cognitive impairment of HE, which is a potential treatment method.

Effect of dihydroquercetin on the toxic properties of nickel nanoparticles

Dihydroquercetin (3,5,7,3',4'-pentahydroxy-flavanone) is known for its powerful antioxidant, organ-protective, and antiinflammatory activities that can be applied to heavy-metal intoxication. The present research objective was to evaluate the possible protective potential of dietary dihydroquercetin in a rat model of subacute (92 days) intoxication with nickel nanoparticles.&#x0D; The experiment involved five groups of twelve male Wistar rats in each. Group 1 served as control. Other groups received nickel nanoparticles as part of their diet. Groups 2 and 4 received nickel nanoparticles with an average diameter of 53.7 nm (NiNP1), while groups 3 and 5 were fed with nanoparticles with an average diameter of 70.9 nm (NiNP2). The dose was calculated as 10 mg/kg b.w. Groups 4 and 5 also received 23 mg/kg b.w. of water-soluble stabilized dihydroquercetin with drinking water. &#x0D; After the dihydroquercetin treatment, the group that consumed 53.7 nm nickel nanoparticles demonstrated lower blood serum glucose, triglycerides, low-density lipoprotein cholesterol, and creatinine. Dihydroquercetin prevented the increase in total protein and albumin fraction associated with nickel nanoparticles intake. The experimental rats also demonstrated lower levels of pro-inflammatory cytokines IL-1β, IL-4, IL-6, and IL-17A, as well as a lower relative spleen weight after the treatment. In the group exposed to 53.7 nm nickel nanoparticles, the dihydroquercetin treatment increased the ratio of cytokines IL-10/IL-17A and decreased the level of circulating FABP2 protein, which is a biomarker of increased intestinal barrier permeability. In the group that received 70.9 nm nickel nanoparticles, the dihydroquercetin treatment inhibited the expression of the fibrogenic Timp3 gene in the liver. In the group that received 53.7 nm nickel nanoparticles, dihydroquercetin partially improved the violated morphology indexes in liver and kidney tissue. However, dihydroquercetin restored neither the content of reduced glutathione in the liver nor the indicators of selenium safety, which were suppressed under the effect of nickel nanoparticles. Moreover, the treatment failed to restore the low locomotor activity in the elevated plus maze test.&#x0D; Dihydroquercetin treatment showed some signs of detoxication and anti-inflammation in rats subjected to nickel nanoparticles. However, additional preclinical studies are necessary to substantiate its prophylactic potential in cases of exposure to nanoparticles of nickel and other heavy metals.

Disordered gut microbiota promotes atrial fibrillation by aggravated conduction disturbance and unbalanced linoleic acid/SIRT1 signaling

Emerging evidence suggests an association of dysbiotic gut microbiota (GM) with atrial fibrillation (AF). The current study aimed to determine whether aberrant GM promotes AF development. A fecal microbiota transplantation (FMT) mouse model demonstrated that dysbiotic GM is sufficient to enhance AF susceptibility assessed by transesophageal burst pacing. Compared with recipients transplanted with GM obtained from healthy subjects (FMT-CH), the prolonged P wave duration and an enlarging tendency for the left atrium were detected in recipients transplanted with AF GM (FMT-AF). Meanwhile, the disrupted localizations of connexin 43 and N-cadherin and increased expression levels of phospho-CaMKII and phospho-RyR2, were observed in the atrium of FMT-AF, which indicated aggravated electrical remodeling caused by the altered gut flora. Specifically, exacerbated fibrosis disarray, collagen deposition, α-SMA expression, and inflammation in the atrium were also confirmed to be transmissible by the GM. Furthermore, deteriorated intestinal epithelial barrier and intestinal permeability, accompanied by disturbing metabolomic features in both feces and plasma, especially decreased linoleic acid (LA), were identified in FMT-AF mice. Subsequently, the anti-inflammatory role of LA among the imbalanced SIRT1 signaling discovered in the atrium of FMT-AF was confirmed in mouse HL-1 cells treated with LPS/nigericin, LA, and SIRT1 knockdown. This study provides preliminary insights into the causal role of aberrant GM in the pathophysiology of AF, suggesting the GM-intestinal barrier-atrium axis might participate in the vulnerable substrates for AF development, and the GM could be utilized as an environmental target in AF management.

Serum rescues surgical manipulation induced intestinal barrier permeability greater than interleukin 1 receptor antagonist conditioned serum in large animal model

Surgical manipulation induced intestinal barrier permeability has been previously demonstrated in rodent models and may prove crucial in the development of postoperative complications such as postoperative ileus and sepsis. However, the observation of this phenomena in a large animal model, and further understanding of mechanisms as well as potential therapeutic approaches has yet to be fully explored. The enteric glial cell population may prove to be a critical participant as they sense the intestinal environment and communicate rapidly with surrounding cell populations. Blockade of glial IL-1 receptor has proven successful in preventing postoperative ileus, a possible sequela of barrier permeability, in a rodent model. Therefore, we hypothesized that a large animal model would demonstrate surgical manipulation-induced intestinal barrier permeability, which could be prevented by luminal injection of interleukin 1 receptor antagonist conditioned serum (IRAP). Ischemia was first induced in the distal jejunum of 6–8-week-old pigs to mimic the disease process that would require intestinal surgery. Jejunum proximal and distal to the ischemic loops was then manipulated by “milking” the intestinal contents and applying friction to the serosa with sterile gauze with and without the injection of 1ml of nonconditioned porcine serum or IRAP into the proximal or distal loop. Forty-five minutes after manipulation, the tissues were collected for immunofluorescence histology and mounted on Ussing chambers to measure transepithelial electrical resistance (TEER) which directly corresponds to mucosal barrier resistance. TEER values for the manipulated proximal intestine were significantly more permeable than control tissue (p&lt;0.0001). In addition, preliminary fluorescent quantification has indicated an increase in glial marker, glial fibrillary acidic protein, in the manipulated tissue (p =0.0499). TEER values for manipulated distal tissue trended towards increased permeability compared to control tissue (p=0.1995). Addition of IRAP significantly increased the resistance of the proximal loop compared to manipulation alone (p=0.0003). Interestingly, addition of control porcine serum significantly increased the resistance of both the proximal and distal loops compared to manipulation alone, and to a greater extent than IRAP (p= &lt;0.0001 and 0.0008 respectively).While the effects of IRAP on interleukin 1 signaling may play a role in prevention of surgical manipulation induced intestinal barrier permeability, it appears than non-conditioned serum may offer therapeutic benefits. Ongoing studies will focus on determining the mechanism of this therapeutic effect on the intestinal epithelia and glia population. NIH K01 OD 028207, NIH-NICHD R01 HD095876 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

ErbB3 Control of Pmp22 Regulates Intestinal Barrier Function

Background: ErbB3 is a member of the ErbB/EGFR family of receptor tyrosine kinases and is the constitutively-expressed neuregulin (NRG) receptor in the intestinal epithelium. Pathways downstream of ErbB3 have been implicated in regulating tight junctions in other systems, but a role for ErbB3 in barrier function in the intestines has not been described. Here we tested the hypothesis that ErbB3 is required for maintenance of normal barrier function in the intestine. Methods: We generated Villin-Cre;ErbB3 flox/flox mice (ErbB3-IEKO) with ErbB3 deletion in the intestinal epithelium. All comparisons are to ErbB3 flox/flox littermate controls. Mice were given a FITC-dextran 4 kDa (FD4) gavage to assess intestinal permeability. Isolated epithelial ileal samples were collected for RT-qPCR, immunohistochemistry, and bulk RNA-seq analysis. Enteroids were generated and treated with the ErbB3 ligand NRG-1β as well as PD153035 and CP-724714 to inhibit EGFR and ErbB2, respectively. Enteroids were also fixed and stained for whole mount immunofluorescence staining. Caco-2BBe cells were grown on Transwell filters, treated with NRG-1β, and assessed for transepithelial electrical resistance (TEER) and FD4 flux. Results: ErbB3-IEKO mice displayed increased intestinal barrier permeability to FD4 compared to controls (p &lt; 0.01). RNA-seq analysis showed a decrease in the expression of the putative tight junction protein Pmp22 in ErbB3-IEKO mice, while other tight junctional components were unchanged. RT-qPCR analysis of ileal samples showed an 80% Pmp22 downregulation (p &lt; 0.01) with ErbB3 loss compared to controls, with similar results in ErbB3-deficient enteroids. Immunohistochemical analysis confirmed near complete loss of PMP22 in ErbB3-IEKO intestinal epithelium. In vitro, treatment with NRG-1β induced Pmp22 expression (p &lt; 0.001) in control, but not ErbB3-deficient, enteroids. Treatment with PD153035 blocked NRG-1β-driven expression of Pmp22 while treatment with CP-724714 did not, suggesting that EGFR is a critical ErbB3 heterodimer partner in regulating Pmp22. Whole mount staining of enteroids confirmed co-localization of PMP22 with the tight junction protein ZO-1 at the apical junctions. Furthermore, treatment of Caco-2BBe monolayers with NRG-1β increased TEER and reduced FD4 flux, demonstrating active regulation of permeability. Conclusions: We demonstrate that loss of ErbB3 in the intestinal epithelium leads to reduced expression of the tight junction protein PMP22 and impaired barrier function in mice. Co-localization of PMP22 with ZO-1 suggests a role for PMP22 in forming the barrier and may represent a mechanism for regulation of intestinal permeability through the ErbB3-PMP22 axis. Furthermore, increased TEER in Caco-2BBe monolayers following NRG-1β treatment suggests induction of PMP22 may represent a means to enhance barrier function and a potential target for future therapeutic interventions targeting the barrier. Supported by NIH awards R01DK095004 and F31DK131856 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Intestinal Epithelial Cell Intrinsic Zinc Homeostasis is Critical for Host-Microbiome Symbiosis

Abstract A robust intestinal barrier is essential for maintaining host-microbiome symbiosis. Defects in the intestinal barrier are associated with a broad range of inflammatory and metabolic diseases. Pharmacological doses of Zinc (Zn) are widely used to improve intestinal barrier function; however, the precise cellular role of Zn in regulating the intestinal barrier during health and disease is not known. A better understanding of how Zn regulates the gut barrier and intestinal epithelial cells (IEC) could enable the development of targeted Zn-based therapeutic approaches. To understand the impact of Zn homeostasis we developed a mouse model with the transcription factor MTF-1 specifically deleted in IECs (MTF ΔIEC). MTF-1 controls the expression of many different zinc importers and exporters. We find that MTF ΔIECmice had reduced expression of Zn homeostasis machinery, demonstrated a leaky barrier, and showed heightened neutrophil activation in the periphery. Additionally, MTF ΔIECmice had a higher bacterial load at the mucosa and were more susceptible to infection by Crohn’s disease associated adherent invasive E.coli. MTF ΔIECmice showed a striking loss of Paneth cells (PCs) from the small intestinal crypts. PCs are specialized antimicrobial-secreting cells with a unique requirement for Zn, but the exact role of Zn in PCs is not known. Based on our findings we conclude that Zn homeostasis is needed for regulating host-microbiome interaction via modulation of intestinal barrier permeability and maintenance of Paneth cells.Our work demonstrating the impact of zinc homeostasis on host-microbe interactions lays the groundwork for understanding zinc in the context of inflammatory bowel disease and dysbiosis in the mucosal microbiome. This work was supported by the NIH [R01DK113265] to Shipra Vaishnava

Th1 promotes M1 polarization of intestinal macrophages to regulate colitis-related mucosal barrier damage.

This work aimed to investigate the role of helper T cell 1 (Th1) in chronic colitis and its immunoregulatory mechanism. The proportions of Th1 and Th2, and the levels of related cytokines in tissues from patients with inflammatory bowel disease (IBD; ulcerative colitis+Crohn's disease, UC+CD) were detected. DSS was used to induce the mouse model of IBD; thereafter, Th1 cells were induced in vitro and amplified before they were injected intraperitoneally. Later, the changes in life state and body weight of mice were observed, the proportion of M1 macrophages in mucosal tissues and mucosal barrier damage were detected. After treatment with macrophage scavenging agent (Clodronate Liposomes, CLL), the influence of Th1 on IBD mice was observed. Then, the intestinal macrophages were co-cultured with Th1 in vitro to observe the influence of Th1 on the polarization of intestinal macrophages. Besides, cells were treated with the STAT3 inhibitor to further detect the macrophage polarization level. Intestinal macrophages were later co-cultured with intestinal epithelial cells to observe the degree of epithelial cell injury. The Th1 proportions in intestinal tissues of UC and CD patients were higher than those in healthy subjects, but the difference in Th2 proportion was not significant. In the IBD mouse model, Th1 induced the M1 polarization of macrophages, aggravated the intestinal inflammatory response, and resulted in the increased mucosal barrier permeability. Pretreatment with CLL antagonized the effect of Th1 cells, reduced the intestinal tissue inflammatory response and mucosal barrier permeability.

Heat-Killed Lacticaseibacillus paracasei Repairs Lipopolysaccharide-Induced Intestinal Epithelial Barrier Damage via MLCK/MLC Pathway Activation

Intestinal epithelial barrier function is closely associated with the development of many intestinal diseases. Heat-killed Lacticaseibacillus paracasei (HK-LP) has been shown to improve intestinal health and enhance immunity. However, the function of HK-LP in the intestinal barrier is still unclear. This study characterized the inflammatory effects of seven HK-LP (1 μg/mL) on the intestinal barrier using lipopolysaccharide (LPS) (100 μg/mL)-induced Caco-2 cells. In this study, HK-LP 6105, 6115, and 6235 were selected, and their effects on the modulation of inflammatory factors and tight junction protein expression (claudin-1, zona occludens-1, and occludin) were compared. The effect of different cultivation times (18 and 48 h) was investigated in response to LPS-induced intestinal epithelial barrier dysfunction. Our results showed that HK-LP 6105, 6115, and 6235 improved LPS-induced intestinal barrier permeability reduction and transepithelial resistance. Furthermore, HK-LP 6105, 6115, and 6235 inhibited the pro-inflammatory factors (TNF-α, IL-1β, IL-6) and increased the expression of the anti-inflammatory factors (IL-4, IL-10, and TGF-β). HK-LP 6105, 6115, and 6235 ameliorated the inflammatory response. It inhibited the nuclear factor kappa B (NF-κB) signaling pathway-mediated myosin light chain (MLC)/MLC kinase signaling pathway by downregulating the Toll-like receptor 4 (TLR4)/NF-κB pathway. Thus, the results suggest that HK-LP 6150, 6115, and 6235 may improve intestinal health by regulating inflammation and TJ proteins. Postbiotics produced by these strains exhibit anti-inflammatory properties that can protect the intestinal barrier.

The Trichinella spiralis-derived antigens alleviate HFD-induced obesity and inflammation in mice.

Obesity, an increasingly prevalent disease worldwide, is accompanied by chronic inflammation and intestinal dysbiosis. Helminth infections have been increasingly proved to exhibit a protective role in several inflammation-associated diseases. Considering the side effects of live parasite therapy, efforts have been made to develop helminth-derived antigens as promising candidates with fewer adverse effects. This study aimed to evaluate the effect and mechanisms of TsAg (T. spiralis-derived antigens) on obesity and the associated inflammation in high-fat diet (HFD)-fed mice. C57BL/6J mice were fed a normal diet or HFD with or without TsAg treatment. The results reported that TsAg treatment alleviated body weight gain and chronic inflammation induced by HFD. In the adipose tissue, TsAg treatment prevented macrophage infiltration, reduced the expression of Th1-type (IFN-γ) and Th17-type (IL-17A) cytokines while upregulating the production of Th2-type (IL-4) cytokines. Furthermore, TsAg treatment enhanced brown adipose tissue activation and energy and lipid metabolism and reduced intestinal dysbiosis, intestinal barrier permeability and LPS/TLR4 axis inflammation. Finally, the protective role of TsAg against obesity was transmissible via the fecal microbiota transplantation approach. For the first time, our findings showed that TsAg alleviated HFD-induced obesity and inflammation via modulation of the gut microbiota and balancing the immune disorders, suggesting that TsAg might be a safer promising therapeutic strategy for obesity.

Intestinal permeability and its role in the pathogenesis of metabolic disorders (metabolic syndrome). Literature review

The article highlights the role of intestinal barrier permeability in the pathogenesis of «metabolic diseases» (diabetes, obesity, etc.). It has been shown that normal intestinal microbiota plays an important role in maintaining the integrity of the intestinal epithelial barrier, and disruption of its homeostasis significantly affects not only intestinal permeability, but also systemic inflammatory processes, immune function, insulin resistance, and lipid metabolism. It was determined that the «Western» diet provides the microbiota with the tools necessary to counteract the host’s immune system and that these changes can destroy the intestinal barrier and contribute to the development of metabolic endotoxinemia. The increased intestinal permeability to endotoxin plays a key role in the development of metabolic changes due to increased translocation of bacterial waste products and contributes to the development of both local and systemic low‑grade inflammation. Intestinal microbiota, affecting metabolic processes in adipose tissue and liver due to impaired intestinal permeability, can ultimately affect systemic insulin resistance and glucose dysregulation. Alterations in the relationship between intestinal immune cells and the microbiome result in the aberrant inflammatory distortions, they are associated with intestinal barrier disruption, metabolic disease progression, and insulin resistance. Intestinal immune cells make an additional contribution to the metabolic disease by regulating the bioavailability of gastrointestinal hormones, which subsequently control blood glucose levels and also affect intestinal barrier permeability. Abnormalities in the tight junctions of intercellular connections in the intestine are associated with metabolic and inflammatory diseases. Disturbance of the intestinal barrier function has been confirmed both in animal models of metabolic‑associated diseases and in human studies, and it is indicated that this barrier dysfunction is an important cause of the metabolic syndrome. Data on the effect of lifestyle adjustments (dietary changes, exercise) and therapeutic strategies (metformin, pre‑ and probiotics, bariatric surgery) on intestinal permeability have been presented.

Claudin-5, occludin, zonulin and tricellulin levels of children with attention deficit/hyperactivity disorder

Introduction Accumulating studies have pointed out that gut-blood and blood-brain barrier dysfunctions due to the alterations in permeability may play a role in the pathophysiology of neurodevelopmental disorders. Tight junctions are crucial components of these barriers and some peptides including claudin-5, occludin, zonulin and tricellulin are important components of these structures. Objectives This study aimed to investigate the relationship between these molecules and attention deficit hyperactivity disorder (ADHD) in children and adolescents. Methods A total of 57 children with ADHD and 60 controls aged between 6 and 12 years were included in the study. The severity of ADHD symptoms was assessed through a parent-rated questionnaire and Conner’s Continuous Performance Test. Serum levels of biochemical variables were measured using enzyme-linked immunosorbent assay kits. Results Serum claudin-5 and tricellulin levels were significantly lower in the ADHD group compared to the control group. The difference between the groups in terms of serum claudin-5 and tricellulin levels remained significant after controlling for confounding factors such as age, gender and autistic characteristics. There was no significant difference between the groups in terms of serum zonulin and occludin levels. (Table 1) Table 2. Serum claudin-5, occludin, zonulin and tricellulin levels of ADHD and controls ADHD(n=57) Controls(n=60) Statistical Analysis ANCOVAc Mean ± SD Mean ± SD z/t p F p ηp2 Claudin-5 *(ng/mL) 2,14 ± 0,71 2,47 ± 0,71 -3,702 P&lt; 0,001a 10,196 0,002 0,083 Occludin*(ng/mL) 3,75 ± 7,17 2,99 ± 2,75 -0,136 p= 0,892a 0,264 0,608 0,002 Zonulin*(ng/mL) 4,82 ± 5,89 5,06 ± 5,53 -0,076 p= 0,939a 0,008 0,930 &lt; 0,001 Tricellülin(ng/mL) 3,04 ± 0,56 3,34 ± 0,71 -2,552 p= 0.012b 6,650 0,011 0,56 Conclusions These results suggest that claudin-5 and tricellulin may be involved in the etiopathogenesis of ADHD. Alterations in these peptides may affect the brain by leading a dysregulation in intestinal or blood-brain barrier permeability that eventually affects the gut-brain axis. The causal relationship between these peptides and ADHD requires further investigation. Disclosure of Interest None Declared