Intestinal Barrier Integrity Research Articles

Swertiamarin ameliorates 2, 4, 6-trinitrobenzenesulfonic acid-induced colitis in mice by inhibiting intestinal epithelial cell apoptosis

To investigate the mechanism by which swertiamarin (STM) ameliorates CD-like colitis in mice. A Caco-2 cell model of TNF-α-stimulated apoptosis was established and divided into three groups: Con, TNF-α and STM, and the effects of STM on apoptosis and barrier function were assessed by Tunel staining, western blotting, immunofluorescence, and transepithelial electric resistance (TEER). A mouse model of 2, 4, 6-trinitrobenzenesulfonic acid (TNBS) -induced CD-like colitis was established to assess the effects of STM on colitis, intestinal barrier function and epithelial cell apoptosis. The regulatory role of the PI3K/AKT pathway in STM-induced resistance to intestinal epithelial cell apoptosis was investigated in both the cell model and mouse models. TUNEL staining showed that in Caco-2 cells with TNF-α stimulation, STM treatment significantly reduced the percentage of TUNEL-stained cells (P<0.05). STM obviously reduced TNF-α-induced enhancement of cleaved-caspase 3 and Bax expressions (P<0.05), increased Bcl-2 expression (P<0.05), protected intestinal barrier integrity and function by restoring transepithelial electrical resistance (TEER) of the cells, promoted normal localization and expressions of the tight junction proteins (ZO1 and claudin 1) (P<0.05), and inhibited the expression of pro-inflammatory factors (IL-6 and CCL3) (P<0.05) in TNF-α-stimulated Caco-2 cells. In the mouse models, STM significantly alleviated TNBS-induced CD-like colitis and intestinal barrier dysfunction (P<0.05) as shown by improved weight loss, lowered Disease Activity Index (DAI) score and inflammation score, reduction of IL-6 and CCL3 release, and restoration of intestinal barrier permeability, colonic TEER, bacterial translocation, and localization and expressions of the tight junction proteins. Mechanistically, STM inhibited the expressions of p-PI3K and p-AKT in both the cell model and mouse model(P<0.05), and treatment with 740Y-P (a PI3K/AKT pathway activator) significantly attenuated the inhibitory effect of STM on TNF-α-induced apoptosis in Caco-2 cells (P<0.05). STM inhibits intestinal epithelial cell apoptosis at least in part by suppressing activation of the PI3K/AKT pathway to ameliorate intestinal barrier dysfunction and colitis in mice.

The circadian rhythm as therapeutic target in inflammatory bowel disease

Abstract The primary objectives of the management of patients with inflammatory bowel disease (IBD) are to prevent IBD flares, prevent/delay disease progression and improve patients’ quality of life. To this end, one needs to identify risk factor(s) associated with flare-ups and disease progression. We posit that disruption of circadian rhythms is one of the key factors that is associated with risk of flare-up and disease progression. This hypothesis is based on published studies that show: (1) The circadian rhythm regulates many biological processes including multiple IBD-relevant biological processes that are critical in inflammatory/immune processes such as environment/microbe interaction, microbe/host interaction, intestinal barrier integrity and mucosal immunity—all central in the pathogenesis of IBD, and (2) Circadian machinery is the primary tool for the host to interact with the environment. Circadian misalignment results in a loss of preparedness of the host to respond and adjust to the environmental changes that could make the host more vulnerable to IBD flare-ups. In this review, we first provide an overview of circadian rhythms and its role in healthy and disease states. Then we present data to support our hypothesis that: (1) IBD patients have disrupted circadian rhythms (“social jet lag”) and (2) circadian misalignment and associated disrupted sleep decreases the resiliency of IBD patients resulting in microbiota dysbiosis, more disrupted intestinal barrier integrity and a more aggressive disease phenotype. We also show that circadian-directed interventions have a potential to mitigate the deleterious impact of disrupted circadian and improve IBD disease course.

Butyrate protects the intestinal barrier by upregulating Fut2 expression via MEK4-JNK signaling pathway activation.

Necrotizing enterocolitis (NEC) is a severe gastrointestinal inflammatory disease in neonates. Fucosyltransferase 2 (Fut2) regulates intestinal epithelial cell fucosylation. In this study, we aimed to investigate butyrate-mediated upregulation of Fut2 expression and the underlying mechanisms. In vivo and in vitro models were established. SP600125 was used to inhibit the MEK4-JNK pathway, and anisomycin was used to activate the MEK4-JNK pathway. Fut2, occludin, and ZO-1 expressions were assessed. Furthermore, intestinal permeability was analyzed by FITC-Dextran. The expression of proteins in the MEK-4-JNK pathway was examined by western blotting. In vivo, the addition of exogenous butyrate notably upregulated Fut2, occludin, and ZO-1 expressions and reduced intestinal permeability in mice with NEC. Butyrate may increase the phosphorylation of MEK4, JNK, and c-jun, which are key components of the MEK4-JNK pathway. Additionally, SP600125 inhibited their phosphorylation, which was reversed by anisomycin treatment. In vitro, butyrate substantially increased occludin and ZO-1 expressions. Butyrate considerably increased Fut2 expression and markedly upregulated p-MEK4, p-JNK, and p-c-jun expressions. SP600125 administration decreased their expressions, while anisomycin administration increased their expressions. Butyrate upregulated Fut2 expression via activation of the MEK4-JNK pathway, improved intestinal barrier integrity, and protected neonatal mice from NEC. We found that exogenous butyrate could improve intestinal barrier integrity and protect against NEC in neonatal mice. Our data showed that exogenous butyrate supplementation upregulated Fut2 expression by activating the MEK4-JNK pathway. Our study provides novel insights into the pathogenesis of NEC, thereby laying an experimental foundation for future clinical research on the use of butyrate in NEC treatment.

Human β-casein-derived peptide BCCY-1 improved the intestinal barrier integrity by regulating the TLR4/eNOS/3-Nitrotyrosine axis

Necrotizing enterocolitis (NEC) is a lethal gastrointestinal disease affecting premature infants. Although earlier studies have highlighted protective effects of milk-derived peptides against NEC, the role of the human β-casein-derived peptide BCCY-1 in intestinal barrier protection has never been investigated. Here, we showed that BCCY-1 alleviated the phenotype of NEC, reduced intestinal expression of Toll-like receptor 4 (TLR4) and interleukin-6, and improved the intestinal barrier integrity. NEC-associated multi-organ injury and impaired bone marrow hematopoiesis were also attenuated by BCCY-1. Metabolic screening revealed significant changes in intestinal metabolites in the NEC and NEC + BCCY-1 groups. Further analysis disclosed inhibition of 3-Nitrotyrosine formation due to the preservation of endothelial nitric oxide synthase (eNOS) activity, which was associated with the interactions between BCCY-1 and lipopolysaccharides, leading to disruption of TLR4 signaling. Our findings suggested that BCCY-1 improved intestinal barrier integrity through modulating the TLR4/eNOS/3-Nitrotyrosine axis, highlighting its potential role in the maintenance of intestinal health.

On probiotic integration in the management of inflammation and the maintenance of the intestinal epithelial barrier’s integrity

Inflammatory bowel disease epidemiology has grown dramatically in recent years, particularly in developed and developing Western countries. Many factors, including stress, diet, and medications, cause and exacerbate inflammatory conditions. Inflammation is closely related to the concept of intestinal barrier integrity. When integrity is compromised, toxins and pathogens can enter the bloodstream. In recent years, there has been a growing interest in using probiotic bacteria to prevent or treat a variety of pathologies, including inflammatory bowel disease. Some studies have looked at the effectiveness of multi-strain probiotic supplements in preventing intestinal barrier dysfunction in in vitro models of lipopolysaccharide-induced inflammation. To mimic the intestinal barrier, human colon adenocarcinoma cell lines were established in Transwell co-culture models. The epithelium permeability was assessed by measuring the transepithelial electrical resistance. The expression of individual proteins involved in barrier function was assessed. The immunomodulatory effects of probiotic formulations were studied in both human macrophage cell lines and ex vivo human peripheral blood mononuclear cell-derived macrophages. The intestinal epithelial layer was also interfaced with a human mast cell line. Selected probiotics have demonstrated high potential for use in maintaining intestinal barrier integrity and possessing anti-inflammatory properties.

Paeonol alleviates ulcerative colitis by modulating PPAR-γ and nuclear factor-κB activation

Ulcerative colitis (UC) is a chronic idiopathic inflammatory disease affecting the gastrointestinal tract. Although paeonol has been used for treating UC due to its anti-inflammatory and antioxidant effects, the underlying mechanisms remain unclear. In this study, we investigated the mechanisms of paeonol’s action on UC by conducting in-vitro and in-vivo studies using NCM460 cells and RAW264.7 cells, and the DSS-induced mice colitis model. The in vitro studies demonstrate that paeonol exerts inhibitory effects on the activation of the NF-κB signaling pathway through upregulating PPARγ expression, thereby attenuating pro-inflammatory cytokine production, reducing reactive oxygen species levels, and promoting M2 macrophage polarization. These effects are significantly abrogated upon addition of the PPARγ inhibitor GW9662. Moreover, UC mice treated with paeonol showed increased PPARγ expression, which reduced inflammation and apoptosis to maintain intestinal epithelial barrier integrity. In conclusion, our findings suggest that paeonol inhibits the NF-κB signaling pathway by activating PPARγ, reducing inflammation and oxidative stress and improving Dss-induced colitis. This study provides a new insight into the mechanism of treating UC by paeonol.

Structure-anti-inflammatory activity relationship of garlic fructans in mice with dextran sulfate sodium-induced colitis: Impact of chain length

The present study identified the protective effects of garlic oligo/poly-saccharides of different chain lengths against dextran sulfate sodium (DSS)-induced colitis in mice and elucidated the structure-function relationships. The results showed that oral intake of garlic oligo/poly-saccharides decreased disease activity index, reduced colon shortening and spleen enlargement, and ameliorated pathological damage in the mouse colon. The dysregulation of colonic pro/anti-inflammatory cytokines was significantly alleviated, accompanied by up-regulated antioxidant enzymes, blocked TLR4-MyD88-NF-κB signaling pathway, enhanced intestinal barrier integrity, and restored SCFA production. Garlic oligo/poly-saccharides also reversed gut microbiota dysbiosis in colitic mice by expanding beneficial bacteria and suppressing the growth of harmful bacteria. High-molecular-weight polysaccharides exhibited stronger alleviating effects on DSS-induced colitic symptoms in mice than low-molecular-weight oligo/poly-saccharides did, probably due to their greater ability to be fermented in the colon. Taken together, this study demonstrated the anti-inflammatory effects of garlic oligo/poly-saccharides and revealed that high-molecular-weight polysaccharide fractions were more effective in alleviating DSS-induced colitis.

Epimedium polysaccharides mitigates Porphyromonas gingivalis-exacerbated intestinal inflammation by suppressing the Th17 pathway and modulating the gut microbiota

This study aimed to investigate the potential alleviating effect of Epimedium polysaccharide (EP) on intestinal inflammation aggravated by Porphyromonas gingivalis (Pg). P. gingivalis, an oral pathogen, may play a role in intestinal inflammation, highlighting the necessity to explore substances capable of inhibiting its pathogenicity. Initially, in vitro screening experiments utilizing co-culturing and quantitative polymerase chain reaction revealed that EP significantly inhibited the growth of P. gingivalis and the levels of virulence genes, including Kgp and RgpA. Subsequent mouse experiments demonstrated that EP notably ameliorated Pg-aggravated weight loss, disease activity index, histopathological lesions, and disruption of intestinal barrier integrity, evidenced by a reduction in tight junction protein levels. Flow cytometry analysis further illustrated that EP attenuated Pg-induced Th17 differentiation and Th17-related cytokines, such as IL-17 and IL-6. Additionally, 16S rRNA amplicon sequencing analysis elucidated that EP significantly mitigated Pg-induced gut microbiota dysbiosis, enriching potentially beneficial microbes, including Akkermansia and Bifidobacterium. The metabolomic analysis provided further insight, indicating that EP intervention altered the accumulation of relevant intestinal metabolites and exhibited correlations with disease indicators. In conclusion, our research suggested that EP holds promise as a prospective therapeutic agent for alleviating P. gingivalis-aggravated intestinal inflammation.

The Potential Role of Butyrate in the Pathogenesis and Treatment of Autoimmune Rheumatic Diseases.

The gut microbiota is a complex ecosystem of microorganisms residing in the human gastrointestinal tract, playing a crucial role in various biological processes and overall health maintenance. Dysbiosis, an imbalance in the composition and function of the gut microbiota, is linked to systemic autoimmune diseases (SAD). Short-chain fatty acids (SCFAs), especially butyrate, produced by the gut microbiota through the fermentation of dietary fibers, play a significant role in immunomodulation and maintaining intestinal homeostasis. Butyrate is essential for colonocyte energy, anti-inflammatory responses, and maintaining intestinal barrier integrity. Studies show reduced butyrate-producing bacteria in SAD patients, suggesting that increasing butyrate levels could have therapeutic benefits. Butyrate's anti-inflammatory effects and its potential therapeutic role have been studied in rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus, systemic sclerosis, and Behçet's disease. Despite promising in vitro and animal model results, human studies are limited, and the optimal strategies for modulating dysbiosis in SADs remain elusive. This review explores the current evidence on the immunoregulatory role of butyrate and its potential therapeutic effects in SAD.

Brain-Gut and Microbiota-Gut-Brain Communication in Type-2 Diabetes Linked Alzheimer's Disease.

The gastrointestinal (GI) tract, home to the largest microbial population in the human body, plays a crucial role in overall health through various mechanisms. Recent advancements in research have revealed the potential implications of gut-brain and vice-versa communication mediated by gut-microbiota and their microbial products in various diseases including type-2 diabetes and Alzheimer's disease (AD). AD is the most common type of dementia where most of cases are sporadic with no clearly identified cause. However, multiple factors are implicated in the progression of sporadic AD which can be classified as non-modifiable (e.g., genetic) and modifiable (e.g. Type-2 diabetes, diet etc.). Present review focusses on key players particularly the modifiable factors such as Type-2 diabetes (T2D) and diet and their implications in microbiota-gut-brain (MGB) and brain-gut (BG) communication and cognitive functions of healthy brain and their dysfunction in Alzheimer's Disease. Special emphasis has been given on elucidation of the mechanistic aspects of the impact of diet on gut-microbiota and the implications of some of the gut-microbial products in T2D and AD pathology. For example, mechanistically, HFD induces gut dysbiosis with driven metabolites that in turn cause loss of integrity of intestinal barrier with concomitant colonic and systemic chronic low-grade inflammation, associated with obesity and T2D. HFD-induced obesity and T2D parallel neuroinflammation, deposition of Amyloid β (Aβ), and ultimately cognitive impairment. The review also provides a new perspective of the impact of diet on brain-gut and microbiota-gut-brain communication in terms of transcription factors as a commonly spoken language that may facilitates the interaction between gut and brain of obese diabetic patients who are at a higher risk of developing cognitive impairment and AD. Other commonality such as tyrosine kinase expression and functions maintaining intestinal integrity on one hand and the phagocytic clarence by migratory microglial functions in brain are also discussed. Lastly, the characterization of the key players future research that might shed lights on novel potential pharmacological target to impede AD progression are also discussed.

Gut microbiota and healthy longevity.

Recent progress on the underlying biological mechanisms of healthy longevity has propelled the field from elucidating genetic modification of healthy longevity hallmarks to defining mechanisms of gut microbiota influencing it. Importantly, the role of gut microbiota in the healthy longevity of the host may provide unprecedented opportunities to decipher the plasticity of lifespan on a natural evolutionary scale and shed light on using microbiota-targeted strategies to promote healthy aging and combat age-related diseases. This review investigates how gut microbiota affects healthy longevity, focusing on the mechanisms through which gut microbiota modulates it. Specifically, we focused on the ability of gut microbiota to enhance the intestinal barrier integrity, provide protection from inflammaging, ameliorate nutrientsensing pathways, optimize mitochondrial function, and improve defense against age-related diseases, thus participating in enhancing longevity and healthspan.

Impact of Mesenchymal Stem Cells on the Gut Microbiota and Microbiota Associated Functions in Inflammatory Bowel Disease: A Systematic Review of Preclinical Evidence on Animal Models.

Inflammatory bowel disease (IBD) is a global health problem in which gut microbiota dysbiosis plays a pivotal pathogenic role. Mesenchymal stem cells (MSCs) therapy has shown promising application prospects for its powerful immune regulation and tissue repair ability. Recent experimental data suggest that MSCs also regulate the composition of gut microbiota. The current review analyzed, for the first time, the research data linking MSCs and gut microbiota modulation in IBD models aiming at assessing the role of gut microbiota in MSCs repair of IBD. A comprehensive and structured literature search was performed up to January 2023 on the PubMed, Web of Science, and Scopus databases. The quality and risk of bias assessment followed the PRISMA guidelines and SYRCLE's tool. A total of nine pre-clinical studies on animal models were included. Although the dose and route of MSCs applied were quite heterogeneous, results showed that MSCs displayed protective effects on intestinal inflammation, including mice general assessment, immunoregulation, and intestinal barrier integrity. Meanwhile, studies showed positive effects on the composition of gut flora with MSCs administration, which had been characterized by restoration of Firmicutes/ Bacteroides balance and reduction of Proteobacteria. The beneficial bacteria Akkermansia, Bifidobacterium, and Lactobacillus were also distinctly enriched, and the pathogenic bacteria Escherichia-Shigella was conversely decreased. The alpha and beta diversity were also regulated to resemble those of healthy mice. Microbial metabolic functions, such as biosynthesis of secondary bile acid and sphingolipid metabolism, and some biological behaviors related to cell regeneration were also up-regulated, while cancer function and poorly characterized cellular function were down-regulated. Current data support the remodeling effect on gut microbiota with MSC administration, which provides a potential therapeutic mechanism for MSCs in the treatment of IBD. Additional studies in humans and animal models are warranted to further confirm the role of gut microflora in MSCs repairing IBD.

Attenuation of arsenic-induced gut injury in mice by sulfated glycosaminoglycan from swim bladder via regulation of gut microbiota, metabolites, and intestinal barrier integrity

Attenuation of arsenic-induced gut injury in mice by sulfated glycosaminoglycan from swim bladder via regulation of gut microbiota, metabolites, and intestinal barrier integrity

Solanum melongena L. Extract Promotes Intestinal Tight Junction Re-Assembly via SIRT-1-Dependent Mechanisms.

Tight junction disruption can lead to pathogenesis of various diseases without therapeutic strategy to recover intestinal barrier integrity. The main objective of this study is to demonstrate the effect of Solanum melongena L. extract (SMLE) on intestinal tight junction recovery and its underlying mechanism. Intestinal barrier function is attenuated by Ca2+ depletion. SMLE treatment increased TER value across T84 cell monolayers. Permeability assay reveals that Ca2+ depletion promotes 4-kDa FITC-dextran permeability, but not 70-kDa FITC-dextran. SMLE suppresses the rate of 4-kDa FITC-dextran permeability, indicating that SMLE inhibits paracellular leak pathway permeability. SMLE-mediated TER increase and leak pathway suppression are abolished by neither calcium/calmodulin-dependent protein kinase kinase β (CaMKKβ) inhibitor nor AMP-activated protein kinase (AMPK) inhibitor. Furthermore, mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinase (ERK) inhibitors have no effects on SMLE-mediated TER increase and leak pathway suppression. Interestingly, SMLE is unable to enhance TER value and diminish leak pathway permeability in T84 cell monolayers pre-treated with sirtuin-1 (SIRT-1) inhibitor. Immunofluorescence staining reveals that SMLE enhances re-assembly of tight junction proteins, including occludin and ZO-1 to intercellular space but this effect is abolished by SIRT-1 inhibitor. These data suggest that SMLE promotes intestinal tight junction re-assembly via SIRT-1-dependent manner.

Lactoferrin alleviates chronic low‑grade inflammation response in obese mice by regulating intestinal flora.

Chronic low‑grade inflammation defines obesity as a metabolic disorder. Alterations in the structure of gut flora are strongly associated with obesity. Lactoferrin (LF) has a biological function in regulating intestinal flora. The present study aimed to investigate the therapeutic and anti‑-inflammatory effects of LF in obese mice based on intestinal flora. A total of 30 C57BL/6 mice were divided into three groups consisting of 10 mice each. Subsequently, one group was fed a normal diet (Group K), another group was fed a high‑fat diet (Group M) and the remaining group switched from regular drinking to drinking 2% LF water (Group Z2) after 2 weeks of high‑fat diet; all mice were fed for 12 weeks. After the experiment, the mouse blood lipid and lipopolysaccharide levels, levels of inflammatory factors and intestinal tight junction proteins were assessed. Mouse stool samples were analyzed using 16S ribosomal RNA sequencing. The results showed that LF reduced serum total cholesterol, triglycerides and low‑density lipoprotein levels, elevated high‑density lipoprotein levels, suppressed metabolic endotoxemia and attenuated chronic low‑grade inflammatory responses in obese mice. In addition, LF upregulated zonula occludens‑1 and occludin protein expression levels in the intestine, thereby improving intestinal barrier integrity. LF altered the intestinal microbial structure of obese mice, reduced the ratio of Firmicutes and an elevated ratio of Bacteroidota, modifying the bacterial population to the increased relative abundance of Alistipes, Acidobacteriota, Psychrobacter and Bryobacter.

The Antidiabetic Potential of Probiotics: A Review.

Diabetes has become one of the most prevalent global epidemics, significantly impacting both the economy and the health of individuals. Diabetes is associated with numerous complications, such as obesity; hyperglycemia; hypercholesterolemia; dyslipidemia; metabolic endotoxemia; intestinal barrier damage; insulin-secretion defects; increased oxidative stress; and low-grade, systemic, and chronic inflammation. Diabetes cannot be completely cured; therefore, current research has focused on developing various methods to control diabetes. A promising strategy is the use of probiotics for diabetes intervention. Probiotics are a class of live, non-toxic microorganisms that can colonize the human intestine and help improve the balance of intestinal microbiota. In this review, we summarize the current clinical studies on using probiotics to control diabetes in humans, along with mechanistic studies conducted in animal models. The primary mechanism by which probiotics regulate diabetes is improved intestinal barrier integrity, alleviated oxidative stress, enhanced immune response, increased short-chain fatty acid production, etc. Therefore, probiotic supplementation holds great potential for the prevention and management of diabetes.

IGF2 contributes to the immunomodulatory effects of exosomes from endometrial regenerative cells on experimental colitis

BackgroundExosomes derived from endometrial regenerative cells (ERC-Exos) can inherit the immunomodulatory function from ERCs, however, whether ERC-Exos exhibit such effect on inflammatory bowel diseases with mucosal immune dysregulation has not been explored. Insulin-like growth factor-Ⅱ (IGF2) is considered to possess the potential to induce an anti-inflammatory phenotype in immune cells. In this study, the contribution of IGF2 in mediating the protective efficacy of ERC-Exos on colitis was investigated. MethodsLentiviral transfection was employed to obtain IGF2-specific knockout ERC-Exos (IGF2-/--ERC-Exos). Experimental colitis mice induced by dextran sulfate sodium (DSS) were divided into the phosphate-buffered saline (untreated), ERC-Exos-treated and IGF2-/--ERC-Exos-treated groups. Colonic histopathological analysis and intestinal barrier function were explored. The infiltration of CD4+ T cells and dendritic cells (DCs) were analyzed by immunofluorescence staining and flow cytometry. The maturation and function of bone marrow-derived dendritic cells (BMDCs) in different exosome administrations were evaluated by flow cytometry, ELISA and the coculture system, respectively. ResultsCompared with the untreated group, ERC-Exos treatment significantly attenuated DSS-induced weight loss, bloody stools, shortened colon length, pathological damage, as well as repaired the weakened intestinal mucosal barrier, including promoting the goblet cells retention, restoring the intestinal barrier integrity and enhancing the expression of tight junction proteins, while the protective effect of exosomes was impaired with the knockout of IGF2 in ERC-Exos. Additionally, IGF2-expressing ERC-Exos decreased the proportions of Th1 and Th17, increased the proportions of Treg, as well as attenuated DC infiltration and maturation in mesenteric lymph nodes and lamina propria of the colitis mice. ERC-Exos were also observed to be phagocytosed by BMDCs and IGF2 is responsible for the modulating effect of ERC-Exos on BMDCs in vitro. ConclusionsExosomes derived from ERCs can exert a therapeutic effect on experimental colitis with remarkable alleviation of the intestinal barrier damage and the abnormal mucosal immune responses. We emphasized that IGF2 plays a critical role for ERC-Exos mediated immunomodulatory function and protection against colitis.

Peroxiredoxin 3 Deficiency Exacerbates DSS-Induced Acute Colitis via Exosomal miR-1260b-Mediated Barrier Disruption and Proinflammatory Signaling.

Aims: Peroxiredoxin3 (Prdx3) is an intracellular antioxidant enzyme that is specifically localized in mitochondria and protects against oxidative stress by removing mitochondrial reactive oxygen species (ROS). The intestinal epithelium provides a physical and biochemical barrier that segregates host tissues from commensal bacteria to maintain intestinal homeostasis. An imbalance between the cellular antioxidant defense system and oxidative stress has been implicated in the pathogenesis of inflammatory bowel disease (IBD). However, the role of Prdx3 in the intestinal epithelium under intestinal inflammation has not been elucidated. To investigate the potential role of Prdx3 in intestinal inflammation, we used intestinal epithelial cell (IEC)-specific Prdx3-knockout mice. Results: IEC-specific Prdx3-deficient mice showed more severe colitis phenotypes with greater degrees of body weight loss, colon shortening, barrier disruption, mitochondrial damage, and ROS generation in IECs. Furthermore, exosomal miR-1260b was dramatically increased in Prdx3-knockdown colonic epithelial cells. Mechanistically, Prdx3 deficiency promoted intestinal barrier disruption and inflammation via P38-mitogen-activated protein kinase/NFκB signaling. Innovation: This is the first study to report the protective role of Prdx3 in acute colitis using IEC-specific conditional knockout mice. Conclusion: Our study sheds light on the role of exosome-loaded miRNAs, particularly miR-1260b, in IBD. Targeting miR-1260b or modulating exosome-mediated intercellular communication may hold promise as potential therapeutic strategies for managing IBD and restoring intestinal barrier integrity.

Effects of elafibranor on liver fibrosis and gut barrier function in a mouse model of alcohol-associated liver disease.

Alcohol-associated liver disease (ALD) is a leading cause of liver-related morbidity and mortality, but there are no therapeutic targets and modalities to prevent ALD-related liver fibrosis. Peroxisome proliferator activated receptor (PPAR) α and δ play a key role in lipid metabolism and intestinal barrier homeostasis, which are major contributors to the pathological progression of ALD. Meanwhile, elafibranor (EFN), which is a dual PPARα and PPARδ agonist, has reached a phase III clinical trial for the treatment of metabolic dysfunction-associated steatotic liver disease and primary biliary cholangitis. However, the benefits of EFN for ALD treatment is unknown. To evaluate the inhibitory effects of EFN on liver fibrosis and gut-intestinal barrier dysfunction in an ALD mouse model. ALD-related liver fibrosis was induced in female C57BL/6J mice by feeding a 2.5% ethanol (EtOH)-containing Lieber-DeCarli liquid diet and intraperitoneally injecting carbon tetrachloride thrice weekly (1 mL/kg) for 8 weeks. EFN (3 and 10 mg/kg/day) was orally administered during the experimental period. Histological and molecular analyses were performed to assess the effect of EFN on steatohepatitis, fibrosis, and intestinal barrier integrity. The EFN effects on HepG2 lipotoxicity and Caco-2 barrier function were evaluated by cell-based assays. The hepatic steatosis, apoptosis, and fibrosis in the ALD mice model were significantly attenuated by EFN treatment. EFN promoted lipolysis and β-oxidation and enhanced autophagic and antioxidant capacities in EtOH-stimulated HepG2 cells, primarily through PPARα activation. Moreover, EFN inhibited the Kupffer cell-mediated inflammatory response, with blunted hepatic exposure to lipopolysaccharide (LPS) and toll like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling. EFN improved intestinal hyperpermeability by restoring tight junction proteins and autophagy and by inhibiting apoptosis and proinflammatory responses. The protective effect on intestinal barrier function in the EtOH-stimulated Caco-2 cells was predominantly mediated by PPARδ activation. EFN reduced ALD-related fibrosis by inhibiting lipid accumulation and apoptosis, enhancing hepatocyte autophagic and antioxidant capacities, and suppressing LPS/TLR4/NF-κB-mediated inflammatory responses by restoring intestinal barrier function.

In vivo RNAi screening identifies multiple deubiquitinases required for the maintenance of intestinal homeostasis in Drosophila

Deubiquitinases (DUBs) are essential for the maintenance of protein homeostasis and assembly of proteins into functional complexes. Despite growing interest in DUBs biological functions, the roles of DUBs in regulating intestinal stem cells (ISCs) and gut homeostasis remain largely unknown. Here, we perform an in vivo RNAi screen through induced knock-down of DUBs expression in adult midgut ISCs and enteroblasts (EBs) to identify DUB regulators of intestinal homeostasis in Drosophila. We screen 43 DUBs and identify 8 DUBs that are required for ISCs homeostasis. Knocking-down of usp1, CG7857, usp5, rpn8, usp10 and csn5 decreases the number of ISCs/EBs, while knocking-down of CG4968 and usp8 increases the number of ISCs/EBs. Moreover, knock-down of usp1, CG4968, CG7857, or rpn8 in ISCs/EBs disrupts the intestinal barrier integrity and shortens the lifespan, indicating the requirement of these DUBs for the maintenance of gut homeostasis. Furthermore, we provide evidences that USP1 mediates ISC lineage differentiation via modulating the Notch signaling activity. Our study identifies, for the first time, the deubiquitinases required for the maintenance of intestinal homeostasis in Drosophila, and provide new insights into the functional links between the DUBs and intestinal homeostasis.