TNF-α Modulation of Intestinal Tight Junction Permeability Is Mediated by NIK/IKK-α Axis Activation of the Canonical NF-κB Pathway

Prevention of colon enlargement by TNF-α antagonist in a streptozotocin-induced diabetic rat model

PURPOSE

We investigated the effect of tumor necrosis factor (TNF)-α antagonist on the structure and function of the streptozotocin-nicotinamide (STZ-NA)-induced diabetic rat colon.

METHODS

Thirty rats were divided into normal control (NC), diabetic control (DC), and diabetic etanercept (DE) groups. The DE group was injected with etanercept twice a week. Blood glucose, body weight, fecal pellet, colonic transit time, and plasma TNF-α were measured. The colon was dissected out, followed by weight and length measurements. Toluidine blue and Verhoeff's staining, immunohistochemistry for TNF-α, RAGE, iNOS, arginase, and western blot for RAGE were performed on the colonic tissue.

RESULTS

Administration of TNF-α antagonist had no significant effect on the body weight and blood glucose level of the diabetic groups. However, the DE group had a shorter and lighter colon and less coarse and less dense collagen fibers in the submucosal layer than the DC group. Weaker immunoreactivity of TNF-α, RAGE, iNOS, and arginase I was observed in colon tissue sections of the DE groups compared with the DC group. Although the etanercept effect on colonic function was not significantly different, the preventive effect size of etanercept on colon remodeling was considerably large, as shown by calculated-Cohen's d>0.8.

CONCLUSIONS

TNF-α signaling in the colonic tissue of diabetic rats has a strong effect on tissue remodeling, leading to colon enlargement. TNF-α antagonists may be beneficial in preventing diabetic-related pathology in the colon in combination with anti-diabetic drugs.

Dysbiosis and fecal microbiota transplant: Contemplating progress in health, neurodegeneration and longevity

The gut-brain axis plays an important role in mental health. The intestinal epithelial surface is colonized by billions of commensal and transitory bacteria, known as the Gut Microbiota (GM). However, potential pathogens continuously stimulate intestinal immunity when they find the place. The last two decades have witnessed several studies revealing intestinal bacteria as a key factor in the health-disease balance of the gut, as well as disease-emergent in other parts of the body. Various neurological processes, such as cognition, learning, and memory, could be affected by dysbiosis in GM. Additionally, the aging process and longevity are related to systemic inflammation caused by dysbiosis. Commensal GM affects brain development, behavior, and healthy aging suggesting that building changes in GM might be a potential therapeutic method. The innovation in GM dysbiosis is intervention by Fecal Microbiota Transplantation (FMT), which has been confirmed as a therapy for recurrent Clostridium difficile infections and is promising for other clinical disorders, such as Parkinson's disease, Multiple Sclerosis (MS), Alzheimer's disease, and depression. Additionally, FMT may be possible to promote healthy aging, and extend longevity. This review aims to connect dysbiosis, neurological disorders, and aging and the potential of FMT as a therapeutic strategy to treat these disorders, and to enhance the quality of life in the elderly.

Association between psychiatric disorders and irritable bowel syndrome: A bidirectional Mendelian randomization study

OBJECTIVE

Previous studies have suggested that irritable bowel syndrome (IBS) is strongly associated with psychiatric disorders. However, it is unclear whether this association is causal, concomitant, or accidental. Thus, we performed Mendelian randomization (MR) analysis to evaluate the causal effects of several psychiatric disorders on IBS.

METHODS

Summary data of genome-wide association studies (GWASs) were obtained mainly from the Psychiatric Genomics Consortium (PGC) on individuals of European ancestry and from a recent GWAS on IBS. We used three MR methods, the inverse-variance weighting (IVW), weighted median (WM), and MR-Egger regression (MR-Egger). In addition, two other indicators, namely, the MR-IVW Cochran's Q statistic and MR-Egger intercept, were used to assess heterogeneity and detect directional horizontal pleiotropy, respectively.

RESULTS

Heritability was high for bipolar disorder (81.18 %, 95 % CI = 73.18-148.18 %), schizophrenia (33.88 %, 95 % CI = 33.57-38.19 %), and panic disorder (30.66 %, 95 % CI = 20.74-40.58 %). For other disorders, there was a low liability-scale SNP heritability for major depressive disorder (MDD) (0.67 %, 95 % CI = 0.61-0.73 %), anxiety disorder (7.63 %, 95 % CI = 1.67-13.59 %), PTSD (0.96 %, 95 % CI = 0.12-1.8 %), and IBS (2.44 %, 95 % CI = 2.13-2.75 %). We also observed that schizophrenia had a significant causal effect on IBS according to MR-IVW. Notably, the individual causal estimates of genetic instruments for MDD and schizophrenia were heterogeneous, but no pleiotropic effects were observed.

CONCLUSIONS

Our analyses revealed the causal effects of MDD and schizophrenia on IBS, a matter that has been subject to debate for decades, and also showed that IBS had causal effects on MDD.

Proinflammatory cytokines suppress stemness-related properties and expression of tight junction in canine intestinal organoids

Recent advancements in canine intestinal organoid research have paved the way for the development of enhanced in vitro models, crucial for exploring intestinal physiology and diseases. Despite these strides, there is a notable gap in creating specific in vitro models that focus on intestinal inflammation. Our study aims to bridge this gap by investigating the impact of proinflammatory cytokines on canine intestinal epithelial cells (IECs) within the context of organoid models. Canine intestinal organoids were treated with proinflammatory cytokines TNF-α, IFN-γ, and IL-1β. The expression of stem cell markers Lgr5, Sox9, Hopx, and Olfm4 was evaluated through RT-qPCR, while membrane integrity was assessed using immunofluorescence staining for tight junction proteins and transport assays for permeability. IFN-γ significantly decreased Lgr5 expression, a key intestinal stem cell marker, at both 24 and 48 h post-treatment (p=0.030 and p=0.002, respectively). Conversely, TNF-α increased Olfm4 expression during the same intervals (p=0.018 and p=0.011, respectively). A reduction in EdU-positive cells, indicative of decreased cell proliferation, was observed following IFN-γ treatment. Additionally, a decrease in tight junction proteins E-cadherin and ZO-1 (p<0.001 and p=0.003, respectively) and increased permeability in IECs (p=0.012) were noted, particularly following treatment with IFN-γ. The study highlights the profound impact of proinflammatory cytokines on canine IECs, influencing both stem cell dynamics and membrane integrity. These insights shed light on the intricate cellular processes underlying inflammation in the gut and open avenues for more in-depth research into the long-term effects of inflammation on intestinal health.

Bifidobacterium bifidum Strain BB1 Inhibits Tumor Necrosis Factor-α-Induced Increase in Intestinal Epithelial Tight Junction Permeability via Toll-Like Receptor-2/Toll-Like Receptor-6 Receptor Complex-Dependent Stimulation of Peroxisome Proliferator-Activated Receptor γ and Suppression of NF-κB p65

Bifidobacterium bifidum strain BB1 causes a strain-specific enhancement in intestinal epithelial tight junction (TJ) barrier. Tumor necrosis factor (TNF)-α induces an increase in intestinal epithelial TJ permeability and promotes intestinal inflammation. The major purpose of this study was to delineate the protective effect of BB1 against the TNF-α-induced increase in intestinal TJ permeability and to unravel the intracellular mechanisms involved. TNF-α produces an increase in intestinal epithelial TJ permeability in Caco-2 monolayers and in mice. Herein, the addition of BB1 inhibited the TNF-α increase in Caco-2 intestinal TJ permeability and mouse intestinal permeability in a strain-specific manner. BB1 inhibited the TNF-α-induced increase in intestinal TJ permeability by interfering with TNF-α-induced enterocyte NF-κB p50/p65 and myosin light chain kinase (MLCK) gene activation. The BB1 protective effect against the TNF-α-induced increase in intestinal permeability was mediated by toll-like receptor-2/toll-like receptor-6 heterodimer complex activation of peroxisome proliferator-activated receptor γ (PPAR-γ) and PPAR-γ pathway inhibition of TNF-α-induced inhibitory kappa B kinase α (IKK-α) activation, which, in turn, resulted in a step-wise inhibition of NF-κB p50/p65, MLCK gene, MLCK kinase activity, and MLCK-induced opening of the TJ barrier. In conclusion, these studies unraveled novel intracellular mechanisms of BB1 protection against the TNF-α-induced increase in intestinal TJ permeability. The current data show that BB1 protects against the TNF-α-induced increase in intestinal epithelial TJ permeability via a PPAR-γ-dependent inhibition of NF-κB p50/p65 and MLCK gene activation.

Prevalence of perturbed gut microbiota in pathophysiology of arsenic-induced anxiety- and depression-like behaviour in mice

Severe toxic effects of arsenic on human physiology have been of immense concern worldwide. Arsenic causes irrevocable structural and functional disruption of tissues, leading to major diseases in chronically exposed individuals. However, it is yet to be resolved whether the effects result from direct deposition and persistence of arsenic in tissues, or via activation of indirect signaling components. Emerging evidences suggest that gut inhabitants play an active role in orchestrating various aspects of brain physiology, as the gut-brain axis maintains cognitive health, emotions, learning and memory skills. Arsenic-induced dysbiosis may consequentially evoke neurotoxicity, eventually leading to anxiety and depression. To delineate the mechanism of action, mice were exposed to different concentrations of arsenic. Enrichment of Gram-negative bacteria and compromised barrier integrity of the gut enhanced lipopolysaccharide (LPS) level in the bloodstream, which in turn elicited systemic inflammation. Subsequent alterations in neurotransmitter levels, microglial activation and histoarchitectural disruption in brain triggered onset of anxiety- and depression-like behaviour in a dose-dependent manner. Finally, to confirm whether the neurotoxic effects are specifically a consequence of modulation of gut microbiota (GM) by arsenic and not arsenic accumulation in the brain, fecal microbiota transplantations (FMT) were performed from arsenic-exposed mice to healthy recipients. 16S rRNA gene sequencing indicated major alterations in GM population in FMT mice, leading to severe structural, functional and behavioural alterations. Moreover, suppression of Toll-like receptor 4 (TLR4) using vivo-morpholino oligomers (VMO) indicated restoration of the altered parameters towards normalcy in FMT mice, confirming direct involvement of the GM in inducing neurotoxicity through the arsenic-gut-brain axis. This study accentuates the potential role of the gut microbiota in promoting neurotoxicity in arsenic-exposed mice, and has immense relevance in predicting neurotoxicity under altered conditions of the gut for designing therapeutic interventions that will target gut dysbiosis to attenuate arsenic-mediated neurotoxicity.

Monoclonal Antibody Against Mature Interleukin-18 Ameliorates Colitis in Mice and Improves Epithelial Barrier Function

BACKGROUND

Antitumor necrosis factor (TNF)-α antibodies have improved the outcome of inflammatory bowel disease (IBD); but half of patients remain unresponsive to treatment. Interleukin-18 (IL-18) gene polymorphism is associated with resistance to anti-TNF-α antibodies, but therapies targeting IL-18 have not been clinically applied. Only the mature protein is biologically active, and we aimed to investigate whether specific inhibition of mature IL-18 using a monoclonal antibody (mAb) against a neoepitope of caspase-cleaved mature IL-18 could be an innovative treatment for IBD.

METHODS

The expression of precursor and mature IL-18 in patients with UC was examined. Colitis was induced in C57/BL6 mice by administering dextran sulfate sodium (DSS), followed by injection with anti-IL-18 neoepitope mAb. Colon tissues were collected and subjected to histological analysis, immunohistochemistry, immunoblotting, and quantitative polymerase chain reaction. Colon epithelial permeability and microbiota composition were analyzed.

RESULTS

Mature IL-18 expression was elevated in colon tissues of patients with active ulcerative colitis. Administration of anti-IL-18 neoepitope mAb ameliorated acute and chronic DSS-induced colitis; reduced interferon-γ, TNF-α, and chemokine (CXC motif) ligand-2 production and epithelial cell permeability; promoted goblet cell function; and altered the intestinal microbiome composition. The suppressive effect of anti-IL-18 neoepitope mAb was superior to that of anti-whole IL-18 mAb. Furthermore, combination therapy with anti-TNF-α Ab suppressed acute and chronic colitis additively by suppressing cytokine expressions and reducing cell permeability by upregulating claudin1 and occludin expression.

CONCLUSIONS

Anti-IL-18 neoepitope mAb ameliorates acute and chronic colitis, suggesting that this mAb will be an innovative therapeutic option for IBD.

Inflammatory bowel disease alters in vivo distribution of orally administrated nanoparticles: Revealing via SERS tag labeling technique

Nanoparticles (NPs) could be uptake orally and exposed to digestive tract through various sources such as particulate pollutant, nanomedicine and food additive. Inflammatory bowel disease (IBD), as a global disease, induced disruption of the intestinal mucosal barrier and thus altered in vivo distribution of NPs as a possible consequence. However, related information was relatively scarce. Herein, in vivo distribution of typical silica (SiO2) and titania (TiO2) NPs was investigated in healthy and IBD models at cell and animal levels via a surface-enhanced Raman scattering (SERS) tag labeling technique. The labeled NPs were composed of gold SERS tag core and SiO2 (or TiO2) shell, demonstrating sensitive and characteristic SERS signals ideal to trace the NPs in vivo. Cell SERS mapping revealed that protein corona from IBD intestinal fluid decreased uptake of NPs by lipopolysaccharide-induced RAW264.7 cells compared with normal intestinal fluid protein corona. SERS signal detection combined with inductively coupled plasma mass spectrometry (ICP-MS) analysis of mouse tissues (heart, liver, spleen, lung and kidney) indicated that both NPs tended to accumulate in lung specifically after oral administration for IBD mouse (6 out of 20 mice for SiO2 and 4 out of 16 mice for TiO2 were detected in lung). Comparatively, no NP signals were detected in all tissues from healthy mice. These findings suggested that there might be a greater risk associated with the oral uptake of NPs in IBD patients due to altered in vivo distribution of NPs.

Lactobacillus acidophilus inhibits the TNF-α-induced increase in intestinal epithelial tight junction permeability via a TLR-2 and PI3K-dependent inhibition of NF-κB activation

Background

Defective intestinal epithelial tight junction (TJ), characterized by an increase in intestinal TJ permeability, has been shown to play a critical role in the pathogenesis of inflammatory bowel disease (IBD). Tumor necrosis factor-α (TNF-α) is a key pro-inflammatory cytokine involved in the immunopathology of IBD and has been shown to cause an increase in intestinal epithelial TJ permeability. Although TNF-α antibodies and other biologics have been advanced for use in IBD treatment, these therapies are associated with severe side effects and have limited efficacy, and there is an urgent need for therapies with benign profiles and high therapeutic efficacy. Probiotic bacteria have beneficial effects and are generally safe and represent an important class of potential therapeutic agents in IBD. Lactobacillus acidophilus (LA) is one of the most used probiotics for wide-ranging health benefits, including in gastrointestinal, metabolic, and inflammatory disorders. A specific strain of LA, LA1, was recently demonstrated to have protective and therapeutic effects on the intestinal epithelial TJ barrier. However, the mechanisms of actions of LA1 remain largely unknown.

Methods

The primary aim of this study was to investigate microbial-epithelial interactions and novel signaling pathways that regulate the effect of LA1 on TNF-α-induced increase in intestinal epithelial TJ permeability, using cell culture and animal model systems.

Results and Conclusion

Pre-treatment of filter-grown Caco-2 monolayers with LA1 prevented the TNF-α-induced increase in intestinal epithelial TJ permeability by inhibiting TNF-α-induced activation of NF-κB p50/p65 and myosin light chain kinase (MLCK) gene and kinase activity in a TLR-2-dependent manner. LA1 produced a TLR-2- and MyD88-dependent activation of NF-κB p50/p65 in immune cells; however, LA1, in intestinal cells, inhibited the NF-κB p50/p65 activation in a TLR-2-dependent but MyD88-independent manner. In addition, LA1 inhibition of NF-κB p50/p65 and MLCK gene was mediated by TLR-2 pathway activation of phosphatidylinositol 3-kinase (PI3K) and IKK-α phosphorylation. Our results demonstrated novel intracellular signaling pathways by which LA1/TLR-2 suppresses the TNF-α pathway activation of NF-κB p50/p65 in intestinal epithelial cells and protects against the TNF-α-induced increase in intestinal epithelial TJ permeability.

Effect of Probiotic Supplementation on Intestinal Permeability in Overweight and Obesity: A Systematic Review of Randomized Controlled Trials and Animal Studies

Overweight and obesity are associated with increased intestinal permeability, characterized by loss of gut epithelial integrity, resulting in unregulated passage of lipopolysaccharide (LPS) and other inflammatory triggers into circulation, i.e., metabolic endotoxemia. In obesity, shifts in the gut microbiome negatively impact intestinal permeability. Probiotics are an intervention that can target the gut microbiome by introducing beneficial microbial species, potentially restoring gut barrier integrity. Currently, the role of probiotic supplementation in ameliorating obesity- and overweight-associated increases in gut permeability has not been reviewed. This systematic review aimed to summarize findings from both animal and clinical studies that evaluated the effect of probiotic supplementation on obesity-induced impairment in intestinal permeability (International Prospective Register of Systematic Reviews, CRD42022363538). A literature search was conducted using PubMed (Medline), Web of Science, and CAB Direct from origin until August 2023 using keywords of intestinal permeability, overweight or obesity, and probiotic supplementation. Of 920 records, 26 eligible records were included, comprising 12 animal and 14 clinical studies. Clinical trials ranged from 3 to 26 wk and were mostly parallel-arm (n = 13) or crossover (n = 1) design. In both animal and clinical studies, plasma/serum LPS was the most common measure of intestinal permeability. Eleven of 12 animal studies reported a positive effect of probiotic supplementation in reducing intestinal permeability. However, results from clinical trials were inconsistent, with half reporting reductions in serum LPS and half reporting no differences after probiotic supplementation. Bifidobacterium, Lactobacillus, and Akkermansia emerged as the most common genera in probiotic formulations among the animal and clinical studies that yielded positive results, suggesting that specific bacteria may be more effective at reducing intestinal permeability and improving gut barrier function. However, better standardization of strain use, dosage, duration, and the delivery matrix is needed to fully understand the probiotic impact on intestinal permeability in individuals with overweight and obesity.

Higher Levels of C-reactive Protein Are Associated With Higher Cortical Surface Area and Lower Cortical Thickness in Youth With Bipolar Disorder

BACKGROUND

Inflammation is implicated in the neuropathology of bipolar disorder (BD). The association of C-reactive protein (CRP) with brain structure has been examined in relation to BD among adults but not youth.

METHODS

Participants included 101 youth (BD, n = 55; control group [CG], n = 46; aged 13-20 years). Blood samples were assayed for levels of CRP. T1-weighted brain images were acquired to obtain cortical surface area (SA), volume, and thickness for 3 regions of interest (ROI; whole-brain cortical gray matter, prefrontal cortex, orbitofrontal cortex [OFC]) and for vertex-wise analyses. Analyses included CRP main effects and interaction effects controlling for age, sex, and intracranial volume.

RESULTS

In ROI analyses, higher CRP was associated with higher whole-brain SA (β = 0.16; P = .03) and lower whole-brain (β = -0.31; P = .03) and OFC cortical thickness (β = -0.29; P = .04) within the BD group and was associated with higher OFC SA (β = 0.17; P = .03) within the CG. In vertex-wise analyses, higher CRP was associated with higher SA and lower cortical thickness in frontal and parietal regions within BD. A significant CRP-by-diagnosis interaction was found in frontal and temporal regions, whereby higher CRP was associated with lower neurostructural metrics in the BD group but higher neurostructural metrics in CG.

CONCLUSIONS

This study found that higher CRP among youth with BD is associated with higher SA but lower cortical thickness in ROI and vertex-wise analyses. The study identified 2 regions in which the association of CRP with brain structure differs between youth with BD and the CG. Future longitudinal, repeated-measures studies incorporating additional inflammatory markers are warranted.

Evaluation of mucosal immune profile associated with Zileuton nanocrystal-formulated BCS-II drug upon oral administration in Sprague Dawley rats

Nanocrystal drug formulation involves several critical manufacturing procedures that result in complex structures to improve drug solubility, dissolution, bioavailability, and consequently the efficacy of poorly soluble Biopharmaceutics Classification System (BCS) II and IV drugs. Nanocrystal formulation of an already approved oral drug may need additional immunotoxic assessment due to changes in the physical properties of the active pharmaceutical ingredient (API). In this study, we selected Zileuton, an FDA-approved drug that belongs to BCS-II for nanocrystal formulation. To evaluate the efficacy and mucosal immune profile of the nanocrystal drug, 10-week-old rats were dosed using capsules containing either API alone or nanocrystal formulated Zileuton (NDZ), or with a physical mixture (PM) using flexible oral gavage syringes. Control groups consisted of untreated, or placebo treated animals. Test formulations were administrated to rats at a dose of 30 mg/kg body weight (bw) once a day for 15 days. The rats treated with NDZ or PM had approximately 4.0 times lower (7.5 mg/kg bw) API when compared to the micron sized API treated rats. At the end of treatment, mucosal (intestinal tissue) and circulating cytokines were measured. The immunological response revealed that NDZ decreased several proinflammatory cytokines in the ileal mucosa (Interleukin-18, Tumor necrosis Factor-α and RANTES [regulated upon activation, normal T cell expressed and secreted]). A similar pattern in the cytokine profile was also observed for the micron sized API and PM treated rats. The cytokine production revealed that there was a significant increase in the production of IL-1β and IL-10 in the females in all experimental groups. Additionally, NDZ showed an immunosuppressive effect on proinflammatory cytokines both locally and systemically, which was similar to the response in micron sized API treated rats. These findings indicate that NDZ significantly decreased several proinflammatory cytokines and it displays less immunotoxicity, probably due to the nanocrystal formulation. Thus, the nanocrystal formulation is more suitable for oral drug delivery, as it exhibited better efficacy, safety, and reduced toxicity.

TNF-α Mediated the Disruption of Hepatic Tight Junction Expression in Blood-Biliary Barrier of Colitis via Downregulating PI3K/AKT Signaling Pathway

Hepatocyte tight junctions (TJ) constituted blood-biliary barrier is the most important hepatic barrier for separating bile from the bloodstream, disruption or dysfunction of TJ barrier is involved in hepatobiliary manifestations of colitis, but the underlying mechanism is still not clear. This study aims to investigate the effect and underlying mechanism of tumor necrosis factor alpha (TNF-α) on hepatic TJ protein expression in blood-biliary barrier and identify its role in the pathogenesis of acute colitis-related cholestasis. Acute colitis rat model was induced by trinitrobenzene sulfonic acid (TNBS) intra-colonic administration. TJs expression of blood-biliary barrier was tested in colitis rats, the serum TNF-α level was also determined in order to elucidate the correlation of TNF-α and TJs. HepaRG cells were used to investigate the effect of TNF-α on TJs, and the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway were also evaluated in rats and TNF-α treated HepaRG cells. Acute colitis was induced in rats at 5 d post TNBS, which is accompanied with cholestasis-like alteration. Serum TNF-α level was increased in colitis rats and positively correlated with the alteration of total bile acids and bilirubin, marked decrease in TJs was found in TNF-α treated HepaRG cells and the rats, down-regulated PI3K/AKT signaling pathway were also identified in TNF-α treated HepaRG cells and the rats. The study concluded that serum TNF-α mediated the down-regulation of PI3K/AKT signaling pathway, which contributed to the reduction of TJ protein expression in acute colitis-related intrahepatic cholestasis. These findings suggest that TNF-α plays an important role in the pathogenesis of intrahepatic cholestasis of colitis.

Depression and risk of gastrointestinal disorders: a comprehensive two-sample Mendelian randomization study of European ancestry

BACKGROUND

Major depressive disorder (MDD) is clinically documented to co-occur with multiple gastrointestinal disorders (GID), but the potential causal relationship between them remains unclear. We aimed to evaluate the potential causal relationship of MDD with 4 GID [gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS), peptic ulcer disease (PUD), and non-alcoholic fatty liver disease (NAFLD)] using a two-sample Mendelian randomization (MR) design.

METHODS

We obtained genome-wide association data for MDD from a meta-analysis (N = 480 359), and for GID from the UK Biobank (N ranges: 332 601-486 601) and FinnGen (N ranges: 187 028-218 792) among individuals of European ancestry. Our primary method was inverse-variance weighted (IVW) MR, with a series of sensitivity analyses to test the hypothesis of MR. Individual study estimates were pooled using fixed-effect meta-analysis.

RESULTS

Meta-analyses IVW MR found evidence that genetically predicted MDD may increase the risk of GERD, IBS, PUD and NAFLD. Additionally, reverse MR found evidence of genetically predicted GERD or IBS may increase the risk of MDD.

CONCLUSIONS

Genetically predicted MDD may increase the risk of GERD, IBS, PUD and NAFLD. Genetically predicted GERD or IBS may increase the risk of MDD. The findings may help elucidate the mechanisms underlying the co-morbidity of MDD and GID. Focusing on GID symptoms in patients with MDD and emotional problems in patients with GID is important for the clinical management.

Butyrate Protects against γ-d-Glutamyl-meso-diaminopimelic Acid-Induced Inflammatory Response and Tight Junction Disruption through Histone Deacetylase 3 Inhibition in Bovine Mammary Epithelial Cells

The present study was conducted to evaluate the regulatory actions and underlying mechanisms of butyrate on the inflammatory response and tight junction (TJ) disruption in bovine mammary epithelial cells (BMECs). Results showed that butyrate declined histone deacetylase 3 (HDAC3) expression, blocked NF-κB activation, and thus suppressed inflammatory cytokine production in γ-d-glutamyl-meso-diaminopimelic acid (iE-DAP)-triggered BMECs. Butyrate also depressed the protein abundance of myosin light chain kinase (MLCK), elevated the expression of TJ proteins, and restored the cellular distribution of TJ proteins and the barrier function of epithelial cells. HDAC3 overexpression abolished the protective effects of butyrate. In conclusion, butyrate alleviated the iE-DAP-induced inflammatory response and TJ injury by blocking NF-κB activation and decreasing inflammatory cytokine production and MLCK expression in a HDAC3-dependent manner. Our finding provides a mechanistic basis for further exploring the regulatory effects of butyrate on the mammary inflammatory response.

Viral manipulation of cell polarity signalling

Cell polarity refers to the asymmetric distribution of biomacromolecules that enable the correct orientation of a cell in a particular direction. It is thus an essential component for appropriate tissue development and function. Viral infections can lead to dysregulation of polarity. This is associated with a poor prognosis due to viral interference with core cell polarity regulatory scaffolding proteins that often feature PDZ (PSD-95, DLG, and ZO-1) domains including Scrib, Dlg, Pals1, PatJ, Par3 and Par6. PDZ domains are also promiscuous, binding to several different partners through their C-terminal region which contain PDZ-binding motifs (PBM). Numerous viruses encode viral effector proteins that target cell polarity regulators for their benefit and include papillomaviruses, flaviviruses and coronaviruses. A better understanding of the mechanisms of action utilised by viral effector proteins to subvert host cell polarity sigalling will provide avenues for future therapeutic intervention, while at the same time enhance our understanding of cell polarity regulation and its role tissue homeostasis.

Intestinal barrier in inflammatory bowel disease: A bibliometric and knowledge-map analysis

BACKGROUND

Barrier surfaces composed of specialized epithelial cells separate the host body from the external environment, and are essential for maintaining proper intestinal physiologic and immune homeostasis.

AIM

To explore the development trends and research hotspots of intestinal barrier research in inflammatory bowel disease (IBD).

METHODS

The publications related to the intestinal barrier in IBD were obtained from the Web of Science Core Collection database. Bibliometric analysis and visualization were conducted using VOSviewer, CiteSpace and R software.

RESULTS

A total of 4482 articles published between 2002 and 2022 were identified. The United States is dominant in intestinal barrier research, whereas the University of Chicago is the most active institution. Jerrold from Harvard Medical School was the most productive authors with the most citations. The journals Inflammatory Bowel Disease and Gastroenterology have made significant contributions in this field. The keywords appearing at high frequency related to the intestinal barrier in IBD were detected, including nuclear factor kappa B, tumor necrosis factor-α, apoptosis, oxidative stress and probiotics. Among them, antioxidants, Akkermansia muciniphila, nanoparticles, short-chain fatty acids and extracellular vesicles have received growing interest in recent research.

CONCLUSION

The intestinal barrier field is developing rapidly with extensive cooperation. Targeting the gut microbiota and dietary metabolism to regulate the intestinal barrier has shown promising prospective applications and has generated broad interest. The importance of the intestinal barrier in IBD is gradually being fully recognized, providing a new therapeutic perspective for improving inflammation and prognosis.

Microbiota-gut-brain axis mechanisms in the complex network of bipolar disorders: potential clinical implications and translational opportunities

Bipolar disorders (BD) represent a severe leading disabling mental condition worldwide characterized by episodic and often progressive mood fluctuations with manic and depressive stages. The biological mechanisms underlying the pathophysiology of BD remain incompletely understood, but it seems that there is a complex picture of genetic and environmental factors implicated. Nowadays, gut microbiota is in the spotlight of new research related to this kind of psychiatric disorder, as it can be consistently related to several pathophysiological events observed in BD. In the context of the so-called microbiota-gut-brain (MGB) axis, it is shown to have a strong influence on host neuromodulation and endocrine functions (i.e., controlling the synthesis of neurotransmitters like serotonin or mediating the activation of the hypothalamic-pituitary-adrenal axis), as well as in modulation of host immune responses, critically regulating intestinal, systemic and brain inflammation (neuroinflammation). The present review aims to elucidate pathophysiological mechanisms derived from the MGB axis disruption and possible therapeutic approaches mainly focusing on gut microbiota in the complex network of BD. Understanding the mechanisms of gut microbiota and its bidirectional communication with the immune and other systems can shed light on the discovery of new therapies for improving the clinical management of these patients. Besides, the effect of psychiatric drugs on gut microbiota currently used in BD patients, together with new therapeutical approaches targeting this ecosystem (dietary patterns, probiotics, prebiotics, and other novelties) will also be contemplated.

Inflammatory macrophages prevent colonic goblet and enteroendocrine cell differentiation through Notch signaling

Inflammatory macrophages in the intestine are a key pathogenic factor driving inflammatory bowel disease (IBD). Here, we report the role of inflammatory macrophage-mediated notch signaling on secretory lineage differentiation in the intestinal epithelium. Utilizing IL-10-deficient (Il10-/-) mice, a model of spontaneous colitis, we found an increase in Notch activity in the colonic epithelium as well as an increase in intestinal macrophages expressing Notch ligands, which are increased in macrophages upon inflammatory stimuli. Furthermore, a co-culture system of inflammatory macrophages and intestinal stem and proliferative cells during differentiation reduced goblet and enteroendocrine cells. This was recapitulated when utilizing a Notch agonist on human colonic organoids (colonoids). In summary, our findings indicate that inflammatory macrophages upregulate notch ligands that activate notch signaling in ISC via cell-cell interactions, which in turn inhibits secretory lineage differentiation in the gastrointestinal (GI) tract.

Serum TGF-β1 and CD14 Predicts Response to Anti-TNF-α Therapy in IBD

Background

Tumor necrosis factor-alpha (TNF-α) agonists revolutionized therapeutic algorithms in inflammatory bowel disease (IBD) management. However, approximately every third IBD patient does not respond to this therapy in the long term, which delays efficient control of the intestinal inflammation.

Methods

We analyzed the power of serum biomarkers to predict the failure of anti-TNF-α. We collected serum of 38 IBD patients at therapy prescription and 38 weeks later and analyzed them with relation to therapy response (no-, partial-, and full response). We used enzyme-linked immunosorbent assay to quantify 16 biomarkers related to gut barrier (intestinal fatty acid-binding protein, liver fatty acid-binding protein, trefoil factor 3, and interleukin (IL)-33), microbial translocation, immune system regulation (TNF-α, CD14, lipopolysaccharide-binding protein, mannan-binding lectin, IL-18, transforming growth factor-β1 (TGF-β1), osteoprotegerin (OPG), insulin-like growth factor 2 (IGF-2), endocrine-gland-derived vascular endothelial growth factor), and matrix metalloproteinase system (MMP-9, MMP-14, and tissue inhibitors of metalloproteinase-1).

Results

We found that future full-responders have different biomarker profiles than non-responders, while partial-responders cannot be distinguished from either group. When future non-responders were compared to responders, their baseline contained significantly more TGF-β1, less CD14, and increased level of MMP-9, and concentration of these factors could predict non-responders with high accuracy (AUC = 0.938). Interestingly, during the 38 weeks, levels of MMP-9 decreased in all patients, irrespective of the outcome, while OPG, IGF-2, and TGF-β1 were higher in non-responders compared to full-responders both at the beginning and the end of the treatment.

Conclusions

The TGF-β1 and CD14 can distinguish non-responders from responders. The changes in biomarker dynamics during the therapy suggest that growth factors (such as OPG, IGF-2, and TGF-β) are not markedly influenced by the treatment and that anti-TNF-α therapy decreases MMP-9 without influencing the treatment outcome.

The Role of Small Intestinal Bacterial Overgrowth in Obesity and Its Related Diseases

Obesity has become a major public health problem worldwide and its occurrence is increasing globally. Obesity has also been shown to be involved in the occurrence and development of many diseases and pathological conditions, such as nonalcoholic fatty liver disease (NAFLD), type 2 diabetes mellitus (T2DM), insulin resistance (IR). In recent years, gut microbiota has received extensive attention as an important regulatory part involved in host diseases and health status. A growing body of evidence suggests that gut microbiota dysbiosis has a significant adverse effect on the host. Small intestinal bacterial overgrowth (SIBO), a type of intestinal microbial dysbiosis, has been gradually revealed to be associated with obesity and its related diseases. The presence of SIBO may lead to the destruction of intestinal barrier integrity, increased intestinal permeability, increased endotoxin levels, activation of inflammatory responses, and translocation of bacteria from the colon to the small intestine. However, the causal relationship between SIBO and obesity and the specific mechanisms have not been well elucidated. This review discusses the cross-talk between SIBO and obesity and its related diseases, and expounds its potential mechanisms and interventions, which may help to discover new therapeutic targets for obesity and its related diseases and develop treatment options.

Cytokines and intestinal epithelial permeability: A systematic review

BACKGROUND

The intestinal mucosa is composed of a well-organized epithelium, acting as a physical barrier to harmful luminal contents, while simultaneously ensuring absorption of physiological nutrients and solutes. Increased intestinal permeability has been described in various chronic diseases, leading to abnormal activation of subepithelial immune cells and overproduction of inflammatory mediators. This review aimed to summarize and evaluate the effects of cytokines on intestinal permeability.

METHODS

A systematic review of the literature was performed in the Medline, Cochrane and Embase databases, up to 01/04/2022, to identify published studies assessing the direct effect of cytokines on intestinal permeability. We collected data on the study design, the method of assessment of intestinal permeability, the type of intervention and the subsequent effect on gut permeability.

RESULTS

A total of 120 publications were included, describing a total of 89 in vitro and 44 in vivo studies. TNFα, IFNγ or IL-1β were the most frequently studied cytokines, inducing an increase in intestinal permeability through a myosin light-chain-mediated mechanism. In situations associated with intestinal barrier disruption, such as inflammatory bowel diseases, in vivo studies showed that anti-TNFα treatment decreased intestinal permeability while achieving clinical recovery. In contrast to TNFα, IL-10 decreased permeability in conditions associated with intestinal hyperpermeability. For some cytokines (e.g. IL-17, IL-23), results are conflicting, with both an increase and a decrease in gut permeability reported, depending on the study model, methodology, or the studied conditions (e.g. burn injury, colitis, ischemia, sepsis).

CONCLUSION

This systematic review provides evidence that intestinal permeability can be directly influenced by cytokines in numerous conditions. The immune environment probably plays an important role, given the variability of their effect, according to different conditions. A better understanding of these mechanisms could open new therapeutic perspectives for disorders associated with gut barrier dysfunction.

Role of Muscarinic Acetylcholine Receptors in Intestinal Epithelial Homeostasis: Insights for the Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, is an intestinal disorder that causes prolonged inflammation of the gastrointestinal tract. Currently, the etiology of IBD is not fully understood and treatments are insufficient to completely cure the disease. In addition to absorbing essential nutrients, intestinal epithelial cells prevent the entry of foreign antigens (micro-organisms and undigested food) through mucus secretion and epithelial barrier formation. Disruption of the intestinal epithelial homeostasis exacerbates inflammation. Thus, the maintenance and reinforcement of epithelial function may have therapeutic benefits in the treatment of IBD. Muscarinic acetylcholine receptors (mAChRs) are G protein-coupled receptors for acetylcholine that are expressed in intestinal epithelial cells. Recent studies have revealed the role of mAChRs in the maintenance of intestinal epithelial homeostasis. The importance of non-neuronal acetylcholine in mAChR activation in epithelial cells has also been recognized. This review aimed to summarize recent advances in research on mAChRs for intestinal epithelial homeostasis and the involvement of non-neuronal acetylcholine systems, and highlight their potential as targets for IBD therapy.

iE-DAP Induced Inflammatory Response and Tight Junction Disruption in Bovine Mammary Epithelial Cells via NOD1-Dependent NF-κB and MLCK Signaling Pathway

γ-D-glutamyl-meso-diaminopimelic acid (iE-DAP), a bacterial cell wall component, can trigger an inflammatory response. A mammary inflammatory response causes tight junction (TJ) dysfunction. This study aimed to explore the effects and involved mechanisms of iE-DAP-induced inflammatory response on the TJ integrity in bovine mammary epithelial cells (BMECs). The results showed that iE-DAP-induced inflammatory response and TJ disruption was associated with increased expression levels of inflammatory cytokines and decreased gene expression of ZO-1 and Occludin, as well as a reduction in transepithelial electrical resistance and elevation in paracellular dextran passage. While MLCK inhibitor ML-7 reversed the TJ disruption induced by iE-DAP. NF-κB inhibitor BAY 11-7085 hindered the activation of NF-κB and MLCK signaling pathways, the inflammatory response and TJ disruption induced by iE-DAP. NOD1-specific shRNA also inhibited the activation of the NOD1/NF-κB signaling pathway and reversed the inflammatory response and TJ injury in iE-DAP-treated BMECs. Above results suggest that iE-DAP activated the NF-κB and MLCK signaling pathway in NOD1-dependent manner, which promoted the transcription of inflammatory cytokines and altered the expression and distribution of tight junction proteins, finally caused inflammatory response and TJ disruption. This study might provide theoretical basis and scientific support for the prevention and treatment of mastitis.

Oligosaccharides of Polygonatum Cyrtonema Hua ameliorates dextran sulfate sodium-induced colitis and regulates the gut microbiota

Ulcerative colitis (UC) is one common chronic inflammatory bowel disease that causes severe side effects, and expensive treatment limits effective and sustained treatment of UC. Fructooligosaccharide was isolated from Polygonatum Cyrtonema Hua (PFOS) and exhibits anti-inflammatory effects. Therefore, we are curious whether PFOS could be used for the treatment of UC. PFOS was introduced via intragastric gavage to C57BL/6 J mice exposed to acute colitis induced by DSS. The results showed that doses of PFOS at 2 and 5 mg/kg/day alleviated the DSS-induced histopathological damage and improved intestinal barrier function. qPCR analysis revealed that PFOS exerted a significant downregulation of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and upregulation of antioxidant genes, including superoxide dismutase1 (SOD1), glutathion peroxidase2 (GPX2), and nuclear factor erythroid 2 related factor2 (Nrf2). Furthermore, PFOS suppressed the DSS-induced disruption of the mucosal barrier by downregulating MMP13. Moreover, using 16 S rRNA gene-based microbiota analysis, PFOS could selectively enhance the growth of probiotics, including Bifidobacterium, Alloprevofella, and Alistipes. Our findings indicated that PFOS attenuated DSS-induced colitis in mice, suggesting that PFOS might be used as an efficacious supplement for reducing inflammatory bowel disease.

Treatment with the Olive Secoiridoid Oleacein Protects against the Intestinal Alterations Associated with EAE

Multiple sclerosis (MS) is a CNS inflammatory demyelinating disease. Recent investigations highlight the gut-brain axis as a communication network with crucial implications in neurological diseases. Thus, disrupted intestinal integrity allows the translocation of luminal molecules into systemic circulation, promoting systemic/brain immune-inflammatory responses. In both, MS and its preclinical model, the experimental autoimmune encephalomyelitis (EAE) gastrointestinal symptoms including "leaky gut" have been reported. Oleacein (OLE), a phenolic compound from extra virgin olive oil or olive leaves, harbors a wide range of therapeutic properties. Previously, we showed OLE effectiveness preventing motor defects and inflammatory damage of CNS tissues on EAE mice. The current studies examine its potential protective effects on intestinal barrier dysfunction using MOG_35-55-induced EAE in C57BL/6 mice. OLE decreased EAE-induced inflammation and oxidative stress in the intestine, preventing tissue injury and permeability alterations. OLE protected from EAE-induced superoxide anion and accumulation of protein and lipid oxidation products in colon, also enhancing its antioxidant capacity. These effects were accompanied by reduced colonic IL-1β and TNFα levels in OLE-treated EAE mice, whereas the immunoregulatory cytokines IL-25 and IL-33 remained unchanged. Moreover, OLE protected the mucin-containing goblet cells in colon and the serum levels of iFABP and sCD14, markers that reflect loss of intestinal epithelial barrier integrity and low-grade systemic inflammation, were significantly reduced. These effects on intestinal permeability did not draw significant differences on the abundance and diversity of gut microbiota. However, OLE induced an EAE-independent raise in the abundance of Akkermansiaceae family. Consistently, using Caco-2 cells as an in vitro model, we confirmed that OLE protected against intestinal barrier dysfunction induced by harmful mediators present in both EAE and MS. This study proves that the protective effect of OLE in EAE also involves normalizing the gut alterations associated to the disease.

Absorption and Transport Mechanism of Red Meat-Derived N-glycolylneuraminic Acid and Its Damage to Intestinal Barrier Function through the NF-κB Signaling Pathway

N-glycolylneuraminic acid (Neu5Gc) is a specific factor in red meat that induces intestinal disease. Our aim was to investigate the effect of Neu5Gc on the intestinal barrier as well as its mechanism of endocytosis and exocytosis. Ten specific inhibitors were used to explore the mechanism of Neu5Gc endocytosis and exocytosis by Caco-2 cells. Amiloride hydrochloride and cytochalasin D had the strongest inhibitory effect on the endocytosis of Neu5Gc. Sodium azide, dynasore, chlorpromazine hydrochloride, and nystatin also inhibited Neu5Gc endocytosis. Dynasore exhibited a stronger inhibitory effect than that of chlorpromazine hydrochloride or nystatin alone. Exocytosis inhibitors, including nocodazole, brefeldin A, monensin, and bafilomycin A, inhibited the transmembrane transport of Neu5Gc. Monensin promoted the exocytosis of Neu5Gc from Caco-2 cells. In another experiment, we observed no significant inhibitory effects of monensin and brefeldin A. Dietary concentrations of Neu5Gc induced prominent damage to intestinal tight junction proteins zonula occludens-1 (ZO-1), occludin, and claudin-1 and promoted the phosphorylation of IκB-α and P65 to activate the canonical Nuclear Factor kappa-B (NF-κB) pathway. Neu5Gc increased the RNA levels of pro-inflammatory factors IL-1β, IL-6, and TNF-α and inhibited those of anti-inflammatory factors TGF-β and IL-10. BAY, an NF-κB signaling pathway inhibitor, attenuated these changes. Reductions in the levels of ZO-1, occludin, and claudin-1 were recovered in response to BAY. Our data reveal the endocytosis and exocytosis mechanism of Neu5Gc and prove that Neu5Gc can activate the canonical NF-κB signaling pathway, regulate the transcription of inflammatory factors, thereby damaging intestinal barrier function.

Paeoniflorin-6'-O-benzene sulfonate protected the intestinal epithelial barrier by restoring the inhibitory effect of GRK2 and β-arrestin 2 on ERK1/2-NF-κB

Peoniflorin-6'-O-benzene sulfonate (CP-25) inhibited the activity of GRK2 to exert anti-inflammatory and immunomodulatory effects. This study aimed to investigate the effect of CP-25 the intestinal epithelial barrier and the mechanism. CaCO-2 cell monolayer and dextran sulfate salt (DSS)-induced colitis mouse model was used to evaluate intestinal epithelial barrier function in vitro and in vivo, respectively. Results showed that CP-25 prevented dysfunction of the intestinal epithelial barrier and inhibited NF-κB p65 activation in TNF-α-induced CaCO-2 cells. The colon structure destroyed in DSS-induced colitis mice was improved by CP-25. CP-25 has a role in inhibition membrane translocation of GRK2-β-arrestin 2 complex, stabilization of the binding of GRK2 and β-arrestin 2 to ERK1/2 in cytoplasm. Subsequently down-regulated the nuclear transcription and transactivation of NF-κB p65 via inhibiting its phosphorylation of Ser536, and Ser276, respectively and restored the epithelial barrier function. In conclusion, CP-25 inhibited ERK1/2-NF-κB activation and thereby protected the intestinal epithelial barrier, which was associated with restoring the inhibition of GRK2 and β-arrestin 2 on ERK1/2.

Serum Levels of IFABP2 and Differences in Lactobacillus and Porphyromonas gingivalis Abundance on Gut Microbiota Are Associated with Poor Therapeutic Response in Rheumatoid Arthritis: A Pilot Study

Intestinal dysbiosis is related to the physiopathology and clinical manifestation of rheumatoid arthritis (RA) and the response to pharmacologic treatment. The objectives of this study were (1) to analyze the effect of conventional synthetic disease modifying anti-rheumatic drugs (csDMARDs) on the abundance of gut microbiota's bacteria; (2) to evaluate the relationship between the differences in microbial abundance with the serum levels of intestinal fatty-acid binding protein 2 (IFABP2), cytokines, and the response phenotype to csDMARDs therapy in RA. A cross-sectional study was conducted on 23 women diagnosed with RA. The abundance of bacteria in gut microbiota was determined with qPCR. The ELISA technique determined serum levels of IFABP2, TNF-α, IL-10, and IL-17A. We found that the accumulated dose of methotrexate or prednisone is negatively associated with the abundance of Lactobacillus but positively associated with the abundance of Bacteroides fragilis. The Lactobacillus/Porphyromonas gingivalis ratio was associated with the Disease Activity Score-28 for RA with Erythrocyte Sedimentation Rate (DAS28-ESR) (r = 0.778, p = 0.030) and with the levels of IL-17A (r = 0.785, p = 0.027) in the group treated with csDMARD. Moreover, a relation between the serum levels of IFABP2 and TNF-α (r = 0.593, p = 0.035) was observed in the group treated with csDMARD. The serum levels of IFABP2 were higher in patients with secondary non-response to csDMARDs therapy. In conclusion, our results suggest that the ratios of gut microbiota's bacteria and intestinal permeability seems to establish the preamble for therapeutic secondary non-response in RA.

Huangshui Polysaccharide Exerts Intestinal Barrier Protective Effects through the TLR4/MyD88/NF-κB and MAPK Signaling Pathways in Caco-2 Cells

Several reports have demonstrated that natural polysaccharides exert protective effects on intestinal barrier function. In our previous study, we isolated a polysaccharide named HSP-W from Huangshui (HS). In the present study, the protective role of HSP-W in LPS-induced intestinal barrier dysfunction was determined by several molecular biological techniques. The results showed that HSP-W treatment alleviated the deduced TEER and increased the permeability of intestinal epithelial cells induced by LPS through inhibiting the release of inflammatory cytokines and enhancing the expression of tight junction (TJ) proteins. The underlying molecular mechanisms were elucidated by RNA-seq technique, which indicated that the differentially expressed genes (DEGs) between the LPS-treated and LPS+HSP-W-treated groups were enriched in the "MAPK" signaling pathway. Notably, the overlapping DEGs reversed by HSP-W intervention highlighted the pathways of the "Toll-like receptor" and "NF-κB" signaling pathways. The suppression of p38 and NF-κB were mediated by the inhibition of MyD88. Furthermore, HSP-W treatment prevented the translocation of NF-κB to nucleus, thus inhibiting the release of TNF-α, IL-6, and IL-1β. Overall, HSP-W has beneficial effects on LPS-induced inflammation; it protects the intestinal barrier from injury in Caco-2 cells through inhibiting the TLR4/MyD88/NF-κB and p38 MAPK signaling pathways.

Biometabolites of Citrus unshiu Peel Enhance Intestinal Permeability and Alter Gut Commensal Bacteria

Flavanones in Citrus unshiu peel (CUP) have been used as therapeutic agents to reduce intestinal inflammation; however, the anti-inflammatory effects of their biometabolites remain ambiguous. Here, we identified aglycone-type flavanones, such as hesperetin and naringenin, which were more abundant in the bioconversion of the CUP than in the ethanol extracts of the CUP. We found that the bioconversion of the CUP induced the canonical nuclear factor-κB pathway via degradation of IκB in Caco-2 cells. To check the immune suppressive capacity of the aglycones of the CUP in vivo, we orally administered the bioconversion of the CUP (500 mg/kg) to mice for two weeks prior to the 3% dextran sulfate sodium treatment. The CUP-pretreated group showed improved body weight loss, colon length shortage, and intestinal inflammation than the control mice. We also found a significant decrease in the population of lamina propria Th17 cells in the CUP-pretreated group following dextran sodium sulfate (DSS) treatment and an increase in mRNA levels of occludin in CUP-treated Caco-2 cells. Pyrosequencing analysis revealed a decreased abundance of Alistipes putredinis and an increased abundance of Muribaculum intestinale in the feces of the CUP-pretreated mice compared to those of the control mice. Overall, these findings suggest that the pre-administration of CUP biometabolites may inhibit the development of murine colitis by modulating intestinal permeability and the gut microbiome.

Maintenance of Enteral ACE2 Prevents Diabetic Retinopathy in Type 1 Diabetes

BACKGROUND

We examined components of systemic and intestinal renin-angiotensin system on gut barrier permeability, glucose homeostasis, systemic inflammation, and progression of diabetic retinopathy (DR) in human subjects and mice with type 1 diabetes (T1D).

METHODS

T1D individual with (n=18) and without (n=20) DR and controls (n=34) were examined for changes in gut-regulated components of the immune system, gut leakage markers (FABP2 [fatty acid binding protein 2] and peptidoglycan), and Ang II (angiotensin II); Akita mice were orally administered a Lactobacillus paracasei (LP) probiotic expressing humanized ACE2 (angiotensin-converting enzyme 2) protein (LP-ACE2) as either a prevention or an intervention. Akita mice with genetic overexpression of humanAce2 by small intestine epithelial cells (Vil-Cre.hAce2KI-Akita) were similarly examined. After 9 months of T1D, circulatory, enteral, and ocular end points were assessed.

RESULTS

T1D subjects exhibit elevations in gut-derived circulating immune cells (ILC1 cells) and higher gut leakage markers, which were positively correlated with plasma Ang II and DR severity. The LP-ACE2 prevention cohort and genetic overexpression of intestinal ACE2 preserved barrier integrity, reduced inflammatory response, improved hyperglycemia, and delayed development of DR. Improvements in glucose homeostasis were due to intestinal MasR activation, resulting in a GSK-3β (glycogen synthase kinase-3 beta)/c-Myc (cellular myelocytomatosis oncogene)-mediated decrease in intestinal glucose transporter expression. In the LP-ACE2 intervention cohort, gut barrier integrity was improved and DR reversed, but no improvement in hyperglycemia was observed. These data support that the beneficial effects of LP-ACE2 on DR are due to the action of ACE2, not improved glucose homeostasis.

CONCLUSIONS

Dysregulated systemic and intestinal renin-angiotensin system was associated with worsening gut barrier permeability, gut-derived immune cell activation, systemic inflammation, and progression of DR in human subjects. In Akita mice, maintaining intestinal ACE2 expression prevented and reversed DR, emphasizing the multifaceted role of the intestinal renin-angiotensin system in diabetes and DR.

Live probiotic bacteria administered in a pathomimetic Leaky Gut Chip ameliorate impaired epithelial barrier and mucosal inflammation

Here, we report a pathomimetic Leaky Gut Chip that recapitulates increased epithelial permeability and intestinal inflammation to assess probiotic intervention as live biotherapeutics. We leveraged a mechanodynamic human gut-on-a-chip (Gut Chip) that recreates three-dimensional epithelial layers in a controlled oxygen gradient and biomechanical cues, where the addition of a cocktail of pro-inflammatory cytokines, TNF-α and IL-1β, reproducibly induced impaired epithelial barrier followed by intestinal inflammation. This inflamed leaky epithelium was not recovered for up to 3 days, although the cytokine treatment ceased. However, when probiotic bacteria, either Lactobacillus rhamnosus GG or a multi-species mixture (VSL#3), were respectively administered on the leaky epithelium, bacterial cells colonized mucosal surface and significantly improved barrier function, enhanced the localization of tight junction proteins such as ZO-1 and occludin, and elevated mucus production. In addition, inflammatory markers, including p65, pSTAT3, and MYD88, that were highly expressed in the germ-free control were significantly reduced when probiotic bacteria were co-cultured in a Leaky Gut Chip. Probiotic treatment also significantly reduced the production of secretory pro-inflammatory cytokines. Hence, our pathomimetic Leaky Gut Chip may offer a translational strategy to dissect the therapeutic mechanism of live biotherapeutic products and validate their clinical potential by incorporating patient-derived organoids.

Weaning stress and intestinal health of piglets: A review

Weaning is considered to be one of the most critical periods in pig production, which is related to the economic benefits of pig farms. However, in actual production, many piglets are often subjected to weaning stress due to the sudden separation from the sow, the changes in diet and living environment, and other social challenges. Weaning stress often causes changes in the morphology and function of the small intestine of piglets, disrupts digestion and absorption capacity, destroys intestinal barrier function, and ultimately leads to reduced feed intake, increased diarrhea rate, and growth retardation. Therefore, correctly understanding the effects of weaning stress on intestinal health have important guiding significance for nutritional regulation of intestinal injury caused by weaning stress. In this review, we mainly reviewed the effects of weaning stress on the intestinal health of piglets, from the aspects of intestinal development, and intestinal barrier function, thereby providing a theoretical basis for nutritional strategies to alleviate weaning stress in mammals in future studies.

Immunogenicity Response of Mus musculus var. Balb/C after Immunization using Flagellin Salmonella typhi Serovar Semarang

&lt;b&gt;Background and Objective:&lt;/b&gt; The flagellin of &lt;i&gt;Salmonella typhi&lt;/i&gt; is potentially developed as an identifying antigen in a rapid diagnostic test instrument that may be more accurate than conventional serological tests. Therefore, this study aims to analyze the immunogenicity of flagellin &lt;i&gt;S. typhi&lt;/i&gt; as the basis for developing a typhoid fever diagnostic. &lt;b&gt;Materials and Methods:&lt;/b&gt; Flagellin was isolated from the bacterial culture of &lt;i&gt;S. typhi&lt;/i&gt; serovar Semarang and used as the primary antigen for vaccine assembly. Native flagellin antigen was immunized in Balb/C mice with injection doses of 2, 3, 4, 5 and 6 g/100 L in each group (K0-K5), respectively, via intraperitoneal cavity. Blood serum was collected to ELISA based-measurement for IL-6 and TNF-a titers. Then, specific immunoglobulin (Ig) of anti-flagellin was detected using in-house ELISA and western blotting. &lt;b&gt;Results:&lt;/b&gt; The findings in this study showed that immunization at the dose of 4-5 g/100 L significantly decreased the IL-6 titer, i.e., 8.33±0.87 pg mL&lt;sup&gt;1&lt;/sup&gt;, compared to control. The antibody titer test analysis showed the highest Ig-G anti-flagellin was found in K4 mice after immunization using a dose of 5 g/100 L with an average absorbance of Ig-G reaching 1.19 ±0.32. &lt;b&gt;Conclusion:&lt;/b&gt; The results indicated that the flagellin protein of &lt;i&gt;S. typhi&lt;/i&gt; serovar Semarang induces adaptive immune responses and produces specific antibodies against flagellin. The immunogenic properties of the flagellin protein of &lt;i&gt;S. typhi&lt;/i&gt; serovar Semarang potentially developed as a specific diagnostic marker. Further research may also focus on a beneficial feature of flagellin as a vaccine candidate.

Ginsenoside Rc attenuates DSS-induced ulcerative colitis, intestinal inflammatory, and barrier function by activating the farnesoid X receptor

Objectives: Farnesoid X receptor (FXR) activation is involved in ameliorating inflammatory bowel disease (IBD), such as ulcerative colitis (UC), and inflammatory regulation may be involved in its mechanism. Ginsenoside Rc (Rc) is a major component of Panax ginseng, and it plays an excellent role in the anti-inflammatory processes. Our aim is to explore the alleviative effect of Rc on dextran sulfate sodium (DSS)-induced inflammation and deficiencies in barrier function based on FXR signaling. Materials and Methods: In vitro, we treated human intestinal epithelial cell lines (LS174T) with LPS to explore the anti-inflammatory effect of Rc supplementation. In vivo, a DSS-induced IBD mice model was established, and the changes in inflammatory and barrier function in colons after Rc treatment were measured using the disease activity index (DAI), hematoxylin and eosin (H&E) staining, immunofluorescence, ELISA, and qPCR. Molecular docking analysis, luciferase reporter gene assay, and qPCR were then used to analyze the binding targets of Rc. DSS-induced FXR-knockout (FXR^-/-) mice were used for further validation. Results: Rc significantly recovered the abnormal levels of inflammation indexes (TNF-α, IL-6, IL-1β, and NF-KB) induced by LPS in LS174T. DSS-induced C57BL/6 mice exhibited a significantly decreased body weight and elevated DAI, as well as a decrease in colon weight and length. Increased inflammatory markers (TNF-α, IL-6, IL-1β, ICAM1, NF-KB, F4/80, and CD11b displayed an increased expression) and damaged barrier function (Claudin-1, occludin, and ZO-1 displayed a decreased expression) were observed in DSS-induced C57BL/6 mice. Nevertheless, supplementation with Rc mitigated the increased inflammatory and damaged barrier function associated with DSS. Further evaluation revealed an activation of FXR signaling in Rc-treated LS174T, with FXR, BSEP, and SHP found to be upregulated. Furthermore, molecular docking indicated that there is a clear interaction between Rc and FXR, while Rc activated transcriptional expression of FXR in luciferase reporter gene assay. However, these reversal abilities of Rc were not observed in DSS-induced FXR^-/- mice. Conclusion: Our findings suggest that Rc may ameliorate inflammation and barrier function in the intestine, which in turn leads to the attenuation of DSS-induced UC, in which Rc may potentially activate FXR signaling to protect the intestines from DSS-induced injury.

Surface layer protein A from hypervirulent Clostridioides difficile ribotypes induce significant changes in the gene expression of tight junctions and inflammatory response in human intestinal epithelial cells

Background

Surface layer protein A (SlpA), the primary outermost structure of Clostridioides difficile, plays an essential role in C. difficile pathogenesis, although its interaction with host intestinal cells are yet to be understood. The aim of this study was to investigate the effects of SlpA extracted from C. difficile on tight junction (TJ) proteins expression and induction of pro-inflammatory cytokines in human colon carcinoma cell line HT-29. SlpA was extracted from three toxigenic C. difficile clinical strains including RT126, RT001, RT084 as well as C. difficile ATCC 700057 as non-toxigenic strain. Cell viability was performed by MTT assay, and the mRNA expression of TJ proteins and inflammation-associated genes was determined using quantitative RT-PCR. Additionally, the secretion of IL-8, IL-1β and TNF-α cytokines was measured by ELISA.

Results

C. difficile SlpA from selected RTs variably downregulated the expression level of TJs-assassinated genes and increased the expression level of TLR-4 and pro-inflammatory cytokines in HT-29 treated cells. SlpA from RT126 significantly (p_adj<0.05) decreased the gene expression level of claudins family and JAM-A and increased the secretion of IL-8, TNF-α and IL1-β as compared to untreated cells. Moreover, only SlpA from RT001 could significantly induce the expression of IL-6 (p_adj<0.05).

Conclusion

The results of the present study highlighted the importance of SlpA in the pathogenesis of CDI and C. difficile-induced inflammatory response in the gut. Further studies are required to unravel the significance of the observed results in promoting the intestinal inflammation and immune response induced by C. difficile SlpA from different RTs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02665-0.

Cocaine administration protects gut mucosa barrier and reduces plasma level of TNF-α

Background

Cocaine affects not only the central nervous system, but also systemic immunity. The role of cocaine in gut mucosal integrity is not fully understood.

Methods

Here we evaluated the effect of cocaine use on gut endothelial permeability and system inflammation in rats that self-administered cocaine or saline and in humans using immunohistochemistry, qPCR, ELISA, and Transepithelial/transendothelial electrical resistance (TEER).

Results

Cocaine administration maintained intact and undisturbed intestinal mucosal structures, increased tight junction claudin 1 and 2 mRNA expression, and decreased plasma TNF-α levels, compared to the control group, at the end of study in rats. Further, cocaine treatment decreased gut endothelial permeability in a dose-dependent manner in human epithelial Caco-2 cells in vitro. Consistently, chronic cocaine users exhibited decreased plasma levels of TNF-α compared with non-drug users in vivo. However, plasma IL-6 levels were similar between cocaine use and control groups both in humans and rats in vivo.

Conclusions

Our results from both human and rat studies in vivo and in vitro suggest that cocaine use may exert a protective effect on the integrity of gut mucosa and suppresses plasma TNF-α levels. This study may provide information on some beneficial effects of cocaine use on gut endothelial cells integrity and systemic inflammation.

Associations between food-specific IgG antibodies and intestinal permeability biomarkers

Increasing translational evidence suggests that intestinal permeability may be a contributing factor to systemic inflammatory events and numerous pathologies. While associations between IgE-mediated food allergies and increased intestinal permeability have been well-characterized, the relationship between IgG-mediated food sensitivities and intestinal permeability is not well-described in the literature. Thus, we tested for associations between intestinal permeability biomarkers and food-specific IgG antibodies in 111 adults, with and without gastrointestinal symptoms. All biomarkers and food-specific IgG antibodies were measured via ELISA. The intestinal permeability biomarkers anti-lipopolysaccharide (LPS) and anti-occludin IgG and IgA antibodies, but not anti-vinculin or anti-CdtB IgG antibodies, were significantly and positively associated with IgG-mediated food sensitivities. These significant relationships were attenuated by adjusting for the severity of wheat, dairy, and egg reactions. The results of this study support strong associations between titers of food-specific IgG antibodies and intestinal permeability biomarkers in adults, to the extent that the presence of multiple IgG antibodies to food, and increasing IgG food titers, can be considered indicative of increased antibodies to LPS and occludin. Notably, neither IgG titers to wheat, eggs, and dairy, nor permeability biomarkers, were increased in symptomatic participants compared to those without symptoms.

Colorectal Cancer in Ulcerative Colitis: Mechanisms, Surveillance and Chemoprevention

Patients with ulcerative colitis (UC) are at a two- to three-fold increased risk of developing colorectal cancer (CRC) than the general population based on population-based data. UC-CRC has generated a series of clinical problems, which are reflected in its worse prognosis and higher mortality than sporadic CRC. Chronic inflammation is a significant contributor to the development of UC-CRC, so comprehending the relationship between the proinflammatory factors and epithelial cells together with downstream signaling pathways is the core to elucidate the mechanisms involved in developing of CRC. Clinical studies have shown the importance of early prevention, detection and management of CRC in patients with UC, and colonoscopic surveillance at regular intervals with multiple biopsies is considered the most effective way. The use of endoscopy with targeted biopsies of visible lesions has been supported in most populations. In contrast, random biopsies in patients with high-risk characteristics have been suggested during surveillance. Some of the agents used to treat UC are chemopreventive, the effects of which will be examined in cancers in UC in a population-based setting. In this review, we outline the current state of potential risk factors and chemopreventive recommendations in UC-CRC, with a specific focus on the proinflammatory mechanisms in promoting CRC and evidence for personalized surveillance.

NF-κB Inducing Kinase Regulates Intestinal Immunity and Homeostasis

Intestinal immunity and homeostasis are maintained through the regulation of cytokine trafficking, microbiota, necrosis and apoptosis. Intestinal immunity and homeostasis participate in host defenses and inflammatory responses locally or systemically through the gut-organ axis. NF-κB functions as a crucial transcription factor mediating the expression of proteins related to the immune responses. The activation of NF-κB involves two major pathways: canonical and non-canonical. The canonical pathway has been extensively studied and reviewed. Here, we present the current knowledge of NIK, a pivotal mediator of the non-canonical NF-κB pathway and its role in intestinal immunity and homeostasis. This review also discusses the novel role of NIK signaling in the pathogenesis and treatment of inflammatory bowel disease.

α7 nicotinic acetylcholine receptor agonist GTS-21 attenuates DSS-induced intestinal colitis by improving intestinal mucosal barrier function

Background and aims

Cholinergic output, which could modulate innate immune responses through stimulation of α7 nicotinic acetylcholine receptor (α7nAChR), might be a target to minimize tissue damage in autoimmune disease. GTS-21, a selective α7nAChR agonist, has previously demonstrated to inhibit synovium inflammation in rheumatoid arthritis. In this study, we investigated the effect of GTS-21 on dextran sulfate sodium (DSS)-induced colitis model and its potential mechanism.

Methods

Male BABL/c mice (n = 32) were randomly divided into four groups: normal control group, DSS-induced colitis group, GTS-21 treatment with or without α7nAChR antagonist α-BGT treatment group. Disease activity index (DAI), histological activity index (HAI) and colonic macroscopic damage were evaluated. Fluorescein isothiocyanate (FITC)–dextran assay was applied to measure intestinal permeability. The expressions of tight junction (TJ) proteins and NF-κB associated proteins were detected by Western blot.

Results

GTS-21 could decrease DAI scores, HAI scores, intestinal permeability and reduce the intestinal bacterial translocation in DSS-induced colitis group, whereas α7nAChR antagonist α-BGT could impair this protective influence. The expressions of TJ proteins were increased with administration of GTS-21 both in vivo and in vitro. Furthermore, GTS-21 also inhibited the NF-қB activation in intestinal epithelial cells and colitis model, while α-BGT reversed the inhibitory effect.

Conclusion

The α7nAChR agonist GTS-21 attenuated DSS-induced colitis through increasing expressions of TJ proteins in colon tissues and improved intestinal barrier function, which might be due to  modulating NF-қB activation in intestinal epithelial cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00485-6.

NF-κB-inducing kinase (NIK) is activated in pancreatic β-cells but does not contribute to the development of diabetes

The transcription factor nuclear factor-κB (NF-κB) has a key role in the pathogenesis of diabetes and its complications. Although activation of the canonical NF-κB pathway in β-cells is generally deleterious, little is known about the role of the non-canonical NF-κB signalling and its main regulator, the NF-κB-inducing kinase (NIK), on pancreatic β-cell survival and function. Previous studies based on models of NIK overexpression in pancreatic islet cells showed that NIK induced either spontaneous β-cell death due to islet inflammation or glucose intolerance during diet-induced obesity (DIO) in mice. Therefore, NIK has been proposed as a potential target for diabetes therapy. However, no clear studies showed whether inhibition of NIK improves diabetes development. Here we show that genetic silencing of NIK in pancreatic β-cells neither modifies diabetes incidence nor inflammatory responses in a mouse model of immune-mediated diabetes. Moreover, NIK silencing in DIO mice did not influence body weight gain, nor glucose metabolism. In vitro studies corroborated the in vivo findings in terms of β-cell survival, function, and downstream gene regulation. Taken together, our data suggest that NIK activation is dispensable for the development of diabetes.

Epithelial protective therapy in comorbid diseases. Practical Guidelines for Physicians

In 2021 the first multidisciplinary National Consensus on the pathophysiological and clinical aspects of Increased Epithelial Permeability Syndrome was published. The proposed guidelines are developed on the basis of this Consensus, by the same team of experts. Twenty-eight Practical Guidelines for Physicians statements were adopted by the Expert Council using the "delphic" method. Such main groups of epithelial protective drugs as proton pump inhibitors, bismuth drugs and probiotics are discussed in these Guidelines from the positions of evidence-based medicine. The clinical and pharmacological characteristics of such a universal epithelial protector as rebamipide, acting at the preepithelial, epithelial and subepithelial levels, throughout gastrointestinal tract, are presented in detail.

Berberine Improves TNF-α-Induced Hepatic Insulin Resistance by Targeting MEKK1/MEK Pathway

Berberine (BBR), a natural isoquinoline alkaloid exhibiting insulin sensitizing activity, has been applicated in the treatment of diabetes. However, until now, the exact target of BBR has not been well investigated. Here, primary hepatocytes pre-treated with TNF-α were used to evaluate the role of BBR on hepatic insulin sensitivity. Western blot and immunoprecipitation were used to investigate the effect of BBR on the crosstalk between TNF-α pathway and insulin signaling pathway. Molecular docking was used to verify the interactions between BBR and its potential targets. BBR inhibits the MEKK1 and MEK1/2, and thus suppresses the activation of their downstream ERK1/2. It attenuates the ERK1/2-induced serine phosphorylation of IRS-1 and thus enhances IRS-1 tyrosine phosphorylation and Akt activation. By molecular docking, BBR is proved to efficiently bind MEK1/2. MEKK1 is also considered as BBR target for its similarity in primary structure with MEK1/2. In conclusion, BBR ameliorates TNF-α-induced hepatic insulin resistance by targeting MEKK1 and MEK1/2.

Molecular mechanism of the TGF‑β/Smad7 signaling pathway in ulcerative colitis

Aberrant TGF‑β/Smad7 signaling has been reported to be an important mechanism underlying the pathogenesis of ulcerative colitis. Therefore, the present study aimed to investigate the effects of a number of potential anti‑colitis agents on intestinal epithelial permeability and the TGF‑β/Smad7 signaling pathway in an experimental model of colitis. A mouse model of colitis was first established before anti‑TNF‑α and 5‑aminosalicyclic acid (5‑ASA) were administered intraperitoneally and orally, respectively. Myeloperoxidase (MPO) activity, histological index (HI) of the colon and the disease activity index (DAI) scores were then detected in each mouse. Transmission electron microscopy (TEM), immunohistochemical and functional tests, including Evans blue (EB) and FITC‑dextran (FD‑4) staining, were used to evaluate intestinal mucosal permeability. The expression of epithelial phenotype markers E‑cadherin, occludin, zona occludens (ZO‑1), TGF‑β and Smad7 were measured. In addition, epithelial myosin light chain kinase (MLCK) expression and activity were measured. Anti‑TNF‑α and 5‑ASA treatments was both found to effectively reduce the DAI score and HI, whilst decreasing colonic MPO activity, plasma levels of FD‑4 and EB permeation of the intestine. Furthermore, anti‑TNF‑α and 5‑ASA treatments decreased MLCK expression and activity, reduced the expression of Smad7 in the small intestine epithelium, but increased the expression of TGF‑β. In mice with colitis, TEM revealed partial epithelial injury in the ileum, where the number of intercellular tight junctions and the expression levels of E‑cadherin, ZO‑1 and occludin were decreased, all of which were alleviated by anti‑TNF‑α and 5‑ASA treatment. In conclusion, anti‑TNF‑α and 5‑ASA both exerted protective effects on intestinal epithelial permeability in an experimental mouse model of colitis. The underlying mechanism may be mediated at least in part by the increase in TGF‑β expression and/or the reduction in Smad7 expression, which can inhibit epithelial MLCK activity and in turn reduce mucosal permeability during the pathogenesis of ulcerative colitis.

Identification of Immune-Related lncRNA Pairs and Construction and Validation of a New Prognostic Signature of Colon Cancer

BACKGROUND

More and more evidence has shown that immune-related long noncoding ribonucleic acid (irlncRNAs) is a potential prognostic factor for colon cancer. The relevant gene pair pattern can improve the sensitivity of the prognostic model. Therefore, our present study aimed to identify irlncRNA Pairs and construct and validate a new prognostic signature in colon cancer.

METHODS

We downloaded the expression matrix of mRNA and lncRNA of patients with colon cancer and their clinical information from the public TCGA database. We obtained immune genes from the ImmPort database. Coexpression analysis was performed to identify irlncRNAs. We built an irlncRNA pair matrix by comparing the expression levels of each lncRNA pair in a cycle. Univariate Cox regression analysis, LASSO penalized regression analysis, and multivariate Cox regression analysis were performed to determine the final variables to construct the prognostic risk score model (a new signature). We draw the receiver operating characteristic (ROC) curves of the signature and clinical characteristics and determine the optimal cutoff value by the optimal Akaike Information Criterion (AIC) value. Based on the optimal cutoff value of the ROC curve of the signature, colon cancer patients were divided into the high- and low-risk groups. Then, the signature was evaluated by clinicopathological features, tumor-infiltrating immune cells, checkpoint-related biomarkers, targeted therapy, and chemotherapy.

RESULTS

We identified 8 lncRNA pairs including AC103740.1|LEF1-AS1, LINC02391|AC053503.5, WWC2-AS2|AL355916.2, AC104090.1|NEURL1-AS1, AC099524.1|AL161908.1, AC074011.1|AL078601.2, AL355916.2|LINC01723, and AP003392.4|LINC00598 from 71 differently expressed irlncRNAs. We constructed a prognostic risk score model (a new signature) using these optimal eight irlncRNA pairs. ROC curve analysis revealed that the highest AUC value of the signature was 0.776 at 1 year, with the optimal cutoff value of 1.283. Our present study also showed that the constructed signature could accurately identify adverse survival outcomes, prognostic clinicopathological features, and specify tumor invasion status. The expression of immune checkpoint-related genes and chemical drug sensitivity were related to different risk groups.

CONCLUSION

In our present study, we constructed a new irlncRNA signature of colon cancer based on the irlncRNA pairs instead of the special expression level of lncRNA. We found this signature had not only good prognostic value but also certain clinical value, which might provide a new insight into the treatment and prognosis of colon cancer.