Gut virome-colonising Orthohepadnavirus genus is associated with ulcerative colitis pathogenesis and induces intestinal inflammation in vivo

OBJECTIVES

Ulcerative colitis (UC) is a chronic inflammatory disorder of unknown aetiology. Gut virome dysbiosis is fundamental in UC progression, although its role in the early phases of the disease is far from fully understood. Therefore, we sought to investigate the role of a virome-associated protein encoded by the Orthohepadnavirus genus, the hepatitis B virus X protein (HBx), in UC aetiopathogenesis.

DESIGN

HBx positivity of UC patient-derived blood and gut mucosa was assessed by RT-PCR and Sanger sequencing and correlated with clinical characteristics by multivariate analysis. Transcriptomics was performed on HBx-overexpressing endoscopic biopsies from healthy donors.C57BL/6 mice underwent intramucosal injections of liposome-conjugated HBx-encoding plasmids or the control, with or without antibiotic treatment. Multidimensional flow cytometry analysis was performed on colonic samples from HBx-treated and control animals. Transepithelial electrical resistance measurement, proliferation assay, chromatin immunoprecipitation assay with sequencing and RNA-sequencing were performed on in vitro models of the gut barrier. HBx-silencing experiments were performed in vitro and in vivo.

RESULTS

HBx was detected in about 45% of patients with UC and found to induce colonic inflammation in mice, while its silencing reverted the colitis phenotype in vivo. HBx acted as a transcriptional regulator in epithelial cells, provoking barrier leakage and altering both innate and adaptive mucosal immunity ex vivo and in vivo.

CONCLUSION

This study described HBx as a contributor to the UC pathogenesis and provides a new perspective on the virome as a target for tailored treatments.

Deletion of Endogenous Neuregulin-4 Limits Adaptive Immunity During Interleukin-10 Receptor-Neutralizing Colitis

BACKGROUND

Growth factors are essential for maintenance of intestinal health. We previously showed that exogenous neuregulin-4 (NRG4) promotes colonocyte survival during cytokine challenge and is protective against acute models of intestinal inflammation. However, the function(s) of endogenous NRG4 are not well understood. Using NRG4-/- mice, we tested the role of endogenous NRG4 in models of colitis skewed toward either adaptive (interleukin-10 receptor [IL-10R] neutralization) or innate (dextran sulfate sodium [DSS]) immune responses.

METHODS

NRG4-/- and wild-type cage mate mice were subjected to chronic IL-10R neutralization colitis and acute DSS colitis. Disease was assessed by histological examination, inflammatory cytokine levels, fecal lipocalin-2 levels, and single cell mass cytometry immune cell profiling. Homeostatic gene alterations were evaluated by RNA sequencing analysis from colonic homogenates, with real-time quantitative polymerase chain reaction confirmation in both tissue and isolated epithelium.

RESULTS

During IL-10R neutralization colitis, NRG4-/- mice had reduced colonic inflammatory cytokine expression, histological damage, and colonic CD8+ T cell numbers vs wild-type cage mates. Conversely, in DSS colitis, NRG4-/- mice had elevated cytokine expression, fecal lipocalin-2 levels, and impaired weight recovery. RNA sequencing showed a loss of St3gal4, a sialyltransferase involved in immune cell trafficking, in NRG4-null colons, which was verified in both tissue and isolated epithelium. The regulation of St3gal4 by NRG4 was confirmed with ex vivo epithelial colon organoid cultures from NRG4-/- mice and by induction of St3gal4 in vivo following NRG4 treatment.

CONCLUSIONS

NRG4 regulates colonic epithelial ST3GAL4 and thus may allow for robust recruitment of CD8+ T cells during adaptive immune responses in colitis. On the other hand, NRG4 loss exacerbates injury driven by innate immune responses.

EPOR activation attenuates colitis via enhancing LC3B-dependent apoptotic cell clearance

Systemic immune activation and excessive inflammatory response, induced by intestinal barrier damage, are the major characteristics of inflammatory bowel disease (IBD). Excessive apoptotic cell accumulation leads to the production of a large number of inflammatory factors, further aggravating IBD development. Gene set enrichment analysis data showed that the homodimeric erythropoietin receptor (EPOR) was highly expressed in the whole blood of patients with IBD. EPOR is specifically expressed in intestinal macrophages. However, the role of EPOR in IBD development is unclear. In this study, we found that EPOR activation significantly alleviated colitis in mice. Furthermore, in vitro, EPOR activation in bone marrow-derived macrophage (BMDMs) promoted microtubule-associated protein 1 light chain 3B (LC3B) activation and mediated the clearance of apoptotic cells. Moreover, our data showed that EPOR activation facilitated the expression of phagocytosis- and tissue-repair-related factors. Our findings suggest that EPOR activation in macrophages promotes apoptotic cell clearance, probably via LC3B-associated phagocytosis (LAP), providing a new mechanism for understanding pathological progression and a novel potential therapeutic target for colitis.

Dexmedetomidine alleviates intestinal barrier dysfunction and inflammatory response in mice via suppressing TLR4/MyD88/NF-κB signaling in an experimental model of ulcerative colitis

INTRODUCTION

Ulcerative colitis (UC) is a nonspecific intestinal inflammatory disease. Dexmedetomidine (DEX) is a selective alpha 2-adrenergic receptor agonist commonly used for analgesia and sedation in intensive care units. Herein, the role and mechanism of DEX in dextran sulfate sodium (DSS)-induced colitis was explored.

MATERIALS AND METHODS

A murine model of DSS-induced colitis was established by adding 3.5% (w/v) DSS in drinking water to C57BL/6J female mice. The severity of colitis was measured by the disease activity index (DAI) score, colon length and body weight of mice. The serum concentration and mRNA levels of inflammatory cytokines in colon tissues were assessed by ELISA and RT-qPCR, respectively. Protein levels of apoptotic markers, tight junction proteins and genes involved in the TLR4/MyD88/NF-κB signaling were quantified utilizing Western blotting. The pathological changes of colon tissues were evaluated by hematoxylin-eosin (HE) staining and histological score. Intestinal permeability in vivo was assessed by fluorescein isothiocyanate (FITC)-dextran (FITC-D) administration. TUNEL assay was used to determine cell apoptosis in the intestinal epithelium.

RESULTS

DSS administration resulted in weight loss, shortening of the colon, increased DAI score, histological abnormalities, and increased serum FITC-D levels in mice, all of which were reversed by DEX injection. Moreover, DEX attenuated DSS-triggered inflammatory response, intestinal barrier injury and intestinal epithelial cell apoptosis. Mechanically, DEX inactivated the TLR4/MyD88/NF-κB signaling in the colon tissues.

CONCLUSIONS

DEX exerts beneficial effects against the intestinal barrier dysfunction, inflammatory response, and apoptosis of intestinal epithelial cells via inactivation of the TLR4/MyD88/NF-κB signaling in mice with DSS-induced colitis.

Natural Compound 2,2',4'-Trihydroxychalcone Suppresses T Helper 17 Cell Differentiation and Disease Progression by Inhibiting Retinoid-Related Orphan Receptor Gamma T

Retinoid-related orphan receptor γt (RORγt), a vital transcription factor for the differentiation of the pro-inflammatory Th17 cells, is essential to the inflammatory response and pathological process mediated by Th17 cells. Pharmacological inhibition of the nuclear receptor RORγt provides novel immunomodulators for treating Th17-driven autoimmune diseases and organ transplant rejection. Here, we identified 2,2',4'-trihydroxychalcone (TDC), a natural chalcone derivant, binds directly to the ligand binding domain (LBD) of RORγt and inhibited its transcriptional activation activity. Using three mice models of Th17-related diseases, it was found that the administration of TDC effectively alleviated the disease development of experimental autoimmune encephalomyelitis (EAE), experimental colitis, and skin allograft rejection. Collectively, these results demonstrated TDC targeting RORγt to suppress Th17 cell polarization, as well as its activity, thus, indicating the potential of this compound in treating of Th17-related autoimmune disorders and organ transplant rejection disorders.

A Japanese Herbal Formula, Daikenchuto, Alleviates Experimental Colitis by Reshaping Microbial Profiles and Enhancing Group 3 Innate Lymphoid Cells

Daikenchuto (DKT) is one of the most widely used Japanese herbal formulae for various gastrointestinal disorders. It consists of Zanthoxylum Fructus (Japanese pepper), Zingiberis Siccatum Rhizoma (processed ginger), Ginseng radix, and maltose powder. However, the use of DKT in clinical settings is still controversial due to the limited molecular evidence and largely unknown therapeutic effects. Here, we investigated the anti-inflammatory actions of DKT in the dextran sodium sulfate (DSS)-induced colitis model in mice. We observed that DKT remarkably attenuated the severity of experimental colitis while maintaining the members of the symbiotic microbiota such as family Lactobacillaceae and increasing levels of propionate, an immunomodulatory microbial metabolite, in the colon. DKT also protected colonic epithelial integrity by upregulating the fucosyltransferase gene Fut2 and the antimicrobial peptide gene Reg3g. More remarkably, DKT restored the reduced colonic group 3 innate lymphoid cells (ILC3s), mainly RORγt^high-ILC3s, in DSS-induced colitis. We further demonstrated that ILC3-deficient mice showed increased mortality during experimental colitis, suggesting that ILC3s play a protective function on colonic inflammation. These findings demonstrate that DKT possesses anti-inflammatory activity, partly via ILC3 function, to maintain the colonic microenvironment. Our study also provides insights into the molecular basis of herbal medicine effects, promotes more profound mechanistic studies towards herbal formulae and contributes to future drug development.

Influence of Rectal Ozone Application on the Intensity of Free Radical Destruction of Lipids and Intestinal Proteins in the Dynamics of Experimental Colitis

We studied clinical status, content of products of LPO, and oxidative modification of proteins (OMP) in the lesion focus of the intestine in experimental colitis under conditions of rectal administration of ozone. Experimental colitis was simulated by two-stage administration of oxazolone; rectal insufflation of ozone in the ozone-oxygen mixture was performed daily. The disease activity index (DAI), the content of calprotectin in the feces, and LPO and OMP products in the intestinal homogenate were assessed. On days 2, 4, and 6 of the pathological process, DAI, concentration of calprotectin in feces, content of primary, secondary, and end-products of LPO in the heptane and isopropanol phases, and content of primary and secondary OMP products progressively increases. Under conditions of ozone application, DAI, concentration of calprotectin in feces, the levels of heptane- and isopropanol-soluble primary, secondary, and end-products of LPO, and the level of primary and secondary products of OMP decreased on days 4 and 6; the level of isopropanol-soluble primary, secondary, end-products of LPO increased on day 2 of experimental colitis. The severity of clinical manifestations weakens as the content of LPO and OMP products in the colon decreases on days 4 and 6 of observation.

Anti-inflammatory Effects of Novel P2X4 Receptor Antagonists, NC-2600 and NP-1815-PX, in a Murine Model of Colitis

The pharmacological blockade of P2X4 receptors has shown potential benefits in the management of several immune/inflammatory diseases. However, data regarding the involvement of P2X4 receptors in the pathophysiological mechanisms of action in intestinal inflammation are not well defined. We aimed to evaluate the anti-inflammatory effects of two novel and selective P2X4 receptor antagonists, NC-2600 and NP-1815-PX, and characterize the molecular mechanisms of their action in a murine model of 2,4-dinitrobenzene sulfonic acid (DNBS)-induced colitis. These two drugs and dexamethasone (DEX) were administered orally for 6 days, immediately after the manifestation of DNBS. The body weight decrease, resulting from colitis, was attenuated by NC-2600 and NP-1815-PX, but not DEX. However, all three drugs attenuated the increase in spleen weight and ameliorated macroscopic and microscopic colonic tissue damage. Furthermore, all three compounds decreased tissue IL-1β levels and caspase-1 expression and activity. Colonic tissue increase of tumor necrosis factor was downregulated by DEX, while both NC-2600 and NP-1815-PX were ineffective. The reduction of occludin associated with colitis was ameliorated by NC-2600 and NP-1815-PX, but not DEX. In THP-1 cells, lipopolysaccharide and ATP upregulated IL-1β release and NLRP3, caspase-1, caspase-5, and caspase-8 activity, but not of caspase-4. These changes were prevented by NC-2600 and NP-1815-PX treatment. For the first time, the above findings show that the selective inhibition of P2X4 receptors represents a viable approach to manage bowel inflammation via the inhibition of NLRP3 inflammasome signaling pathways.

The Combination of Intestinal Alkaline Phosphatase Treatment with Moderate Physical Activity Alleviates the Severity of Experimental Colitis in Obese Mice via Modulation of Gut Microbiota, Attenuation of Proinflammatory Cytokines, Oxidative Stress Biomarkers and DNA Oxidative Damage in Colonic Mucosa

Inflammatory bowel diseases (IBD) are commonly considered as Crohn's disease and ulcerative colitis, but the possibility that the alterations in gut microbiota and oxidative stress may affect the course of experimental colitis in obese physically exercising mice treated with the intestinal alkaline phosphatase (IAP) has been little elucidated. Mice fed a high-fat-diet (HFD) or normal diet (ND) for 14 weeks were randomly assigned to exercise on spinning wheels (SW) for 7 weeks and treated with IAP followed by intrarectal administration of TNBS. The disease activity index (DAI), grip muscle strength test, oxidative stress biomarkers (MDA, SOD, GSH), DNA damage (8-OHdG), the plasma levels of cytokines IL-2, IL-6, IL-10, IL-12p70, IL-17a, TNF-α, MCP-1 and leptin were assessed, and the stool composition of the intestinal microbiota was determined by next generation sequencing (NGS). The TNBS-induced colitis was worsened in obese sedentary mice as manifested by severe colonic damage, an increase in DAI, oxidative stress biomarkers, DNA damage and decreased muscle strength. The longer running distance and weight loss was observed in mice given IAP or subjected to IAP + SW compared to sedentary ones. Less heterogeneous microbial composition was noticed in sedentary obese colitis mice and this effect disappeared in IAP + SW mice. Absence of Alistipes, lower proportion of Turicibacter, Proteobacteria and Faecalibacterium, an increase in Firmicutes and Clostridium, a decrease in oxidative stress biomarkers, 8-OHdG content and proinflammatory cytokines were observed in IAP + SW mice. IAP supplementation in combination with moderate physical activity attenuates the severity of murine colitis complicated by obesity through a mechanism involving the downregulation of the intestinal cytokine/chemokine network and oxidative stress, the modulation of the gut microbiota and an improvement of muscle strength.

The Selective 5-HT1A Agonist SR57746A Protects Intestinal Epithelial Cells and Enteric Glia Cells and Promotes Mucosal Recovery in Experimental Colitis

BACKGROUND

Neurotrophic growth factors can stabilize the intestinal barrier by preventing the apoptosis of enteric glial cells (EGCs) and enterocytes. We reasoned that a selective 5-HT1A receptor agonist may have neuroprotective properties in the gut and that topical application of SR57746A might be an effective treatment strategy in inflammatory bowel disease (IBD).

METHODS

The therapeutic potential of 5-HT1A receptor agonist SR57746A in IBD was evaluated in vitro (nontransformed NCM460 colonic epithelial cells, SW480 colorectal carcinoma cells) and in vivo (murine dextran sulfate sodium [DSS] colitis and CD4-T-cell transfer colitis). In vitro, we analyzed the effect of SR57746A on apoptosis in intestinal epithelial cells (IECs) and EGCs, and upon proliferation, migration, and intracellular signaling in IECs. In vivo, the effect of topical application of SR57746 on disease activity and on histological and endoscopic findings was compared with intraperitoneal infliximab and placebo, respectively.

RESULTS

The SR57746A activates PI3-K/AKT- and ERK-signaling in IECs. Depending on ERK- and AKT activation, SR57746A potently prevents apoptosis of IECs without inducing proliferation or migration in these cells. Moreover, SR57746A prevented apoptosis in EGCs in vitro. Topical SR57746A treatment significantly reduced mucosal injury in 2 experimental murine colitis models and was as effective as intraperitoneal infliximab treatment.

CONCLUSIONS

Treatment with SR57746A prevents inflammatory cell damage and apoptosis in IECs and EGCs, similar to the neurotrophic effects of EGCs on IECs. Topical treatment with SR57746A could be a candidate for clinical evaluation in the treatment of IBD.

Bioactive Compounds from Pale Ale Beer Powder Attenuate Experimental Colitis in BALB/c Mice

Phenolic compounds (PCs) present in foods are associated with a decreased risk of developing inflammatory diseases. The aim of this study was to extract and characterize PCs from craft beer powder and evaluate their potential benefits in an experimental model of inflammatory bowel disease (IBD). PCs were extracted and quantified from pure beer samples. BALB/c mice received either the beer phenolic extract (BPE) or beer powder fortified with phenolic extract (BPFPE) of PCs daily for 20 days by gavage. Colon samples were collected for histopathological and immunohistochemical analyses. Dextran sodium sulfate (DSS)-induced mice lost more weight, had reduced colon length, and developed more inflammatory changes compared with DSS-induced mice treated with either BPE or BPFPE. In addition, in DSS-induced mice, the densities of CD4- and CD11b-positive cells, apoptotic rates, and activation of NF-κB and p-ERK1/2 MAPK intracellular signaling pathways were higher in those treated with BPE and BPFPE than in those not treated. Pretreatment with the phenolic extract and BPFPE remarkably attenuated DSS-induced colitis. The protective effect of PCs supports further investigation and development of therapies for human IBD.

Identification of a gut microbiota member that ameliorates DSS-induced colitis in intestinal barrier enhanced Dusp6-deficient mice

Strengthening the gut epithelial barrier is a potential strategy for management of gut microbiota-associated illnesses. Here, we demonstrate that dual-specificity phosphatase 6 (Dusp6) knockout enhances baseline colon barrier integrity and ameliorates dextran sulfate sodium (DSS)-induced colonic injury. DUSP6 mutation in Caco-2 cells enhances the epithelial feature and increases mitochondrial oxygen consumption, accompanied by altered glucose metabolism and decreased glycolysis. We find that Dusp6-knockout mice are more resistant to DSS-induced dysbiosis, and the cohousing and fecal microbiota transplantation experiments show that the gut/fecal microbiota derived from Dusp6-knockout mice also confers protection against colitis. Further culturomics and mono-colonialization experiments show that one gut microbiota member in the genus Duncaniella confers host protection from DSS-induced injury. We identify Dusp6 deficiency as beneficial for shaping the gut microbiota eubiosis necessary to protect against gut barrier-related diseases.

Corrigendum: Development and Characterization of a New Endoscopic Drug-Eluting Platform With Proven Efficacy in Acute and Chronic Experimental Colitis

[This corrects the article DOI: 10.3389/fmed.2020.00415.].

The Emulsifier Carboxymethylcellulose Induces More Aggressive Colitis in Humanized Mice with Inflammatory Bowel Disease Microbiota Than Polysorbate-80

Commonly used synthetic dietary emulsifiers, including carboxymethylcellulose (CMC) and polysorbate-80 (P80), promote intestinal inflammation. We compared abilities of CMC vs. P80 to potentiate colitis and impact human microbiota in an inflammatory environment using a novel colitis model of ex-germ-free (GF) IL10^−/− mice colonized by pooled fecal transplant from three patients with active inflammatory bowel diseases. After three days, mice received 1% CMC or P80 in drinking water or water alone for four weeks. Inflammation was quantified by serial fecal lipocalin 2 (Lcn-2) and after four weeks by blinded colonic histologic scores and colonic inflammatory cytokine gene expression. Microbiota profiles in cecal contents were determined by shotgun metagenomic sequencing. CMC treatment significantly increased fecal Lcn-2 levels compared to P80 and water treatment by one week and throughout the experiment. Likewise, CMC treatment increased histologic inflammatory scores and colonic inflammatory cytokine gene expression compared with P80 and water controls. The two emulsifiers differentially affected specific intestinal microbiota. CMC did not impact bacterial composition but significantly decreased Caudoviricetes (bacteriophages), while P80 exposure non-significantly increased the abundance of both Actinobacteria and Proteobacteria. Commonly used dietary emulsifiers have different abilities to induce colitis in humanized mice. CMC promotes more aggressive inflammation without changing bacterial composition.

A New Hybrid Protein Is a Novel Regulator for Experimental Colitis in Rats

We newly developed a hybrid protein, tentatively named rMIKO-1, using gene technology. We herein investigated the effects of rMIKO-1 on activated macrophages and discussed its potential as a suppressor of experimental colitis. Fluorescent microscopy was used to observe the dynamic mobility of rMIKO-1 in macrophages. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, fluorescent immunochemical staining, flow cytometry, enzyme-linked immunosorbent assays, a polymerase chain reaction/quantitative polymerase chain reaction, and hematoxylin and eosin staining were conducted to assess the potential activity of rMIKO-1. A large amount of bleeding was observed in rats treated with 5% dextran sulfate sodium (DSS) alone on day 8 after treatment initiation, but not in those treated with 5% DSS plus rMIKO-1. In the in vitro assay, rMIKO-1 rapidly bound to macrophages, immediately entered cells by an unknown mechanism, and then migrated inside the nucleus. This result suggests that rMIKO-1 plays important immunological roles in the nucleus. Despite the activation of macrophages by lipopolysaccharide, the mRNA expression of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin-6, and interleukin-1β, was significantly suppressed in macrophages preliminarily treated with rMIKO-1 for 1 h. Complexes of rMIKO-1 with nuclear factor-kappa B (NF-κB)/p65 and β-actin formed in activated macrophages, which attenuated experimental colitis in rats. These results strongly suggest that rMIKO-1 negatively regulates excessively activated macrophages through the NF-κB/p65 signaling pathway. Therefore, rMIKO-1 is a novel suppressor of experimental colitis in rats through the negative regulation of activated macrophages.

Tailored Hydrogels as Delivery Platforms for Conditioned Medium from Mesenchymal Stem Cells in a Model of Acute Colitis in Mice

Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is increasingly prevalent and current therapies are not completely effective. Mesenchymal stem cells are emerging as a promising therapeutic option. Here, the effect of local hydrogel application loaded with conditioned medium (CM) from human uterine cervical stem cells (hUCESC-CM) in an experimental acute colitis mice model has been evaluated. Colitis induction was carried out in C57BL/6 mice by dissolving dextran sulfate sodium (DSS) in drinking water for nine days. Ulcers were treated by rectal administration of either mesalazine (as positive control) or a mucoadhesive and thermosensitive hydrogel loaded with hUCESC-CM (H-hUCESC-CM). Body weight changes, colon length, and histopathological analysis were evaluated. In addition, pro-inflammatory TNF-α, IL-6, and IFN-γ mRNA levels were measured by qPCR. Treatment with H-hUCESC-CM inhibited body weight loss and colon shortening and induced a significant decrease in colon mucosa degeneration, as well as TNF-α, IFN-γ, and IL-6 mRNA levels. Results indicate that H-hUCESC-CM effectively alleviated DSS-induced colitis in mice, suggesting that H-hUCESC-CM may represent an attractive cell-free therapy for local treatment of IBD.

AeMOPE-1, a Novel Salivary Peptide From Aedes aegypti, Selectively Modulates Activation of Murine Macrophages and Ameliorates Experimental Colitis

The sialotranscriptomes of Aedes aegypti revealed a transcript overexpressed in female salivary glands that codes a mature 7.8 kDa peptide. The peptide, specific to the Aedes genus, has a unique sequence, presents a putative secretory nature and its function is unknown. Here, we confirmed that the peptide is highly expressed in the salivary glands of female mosquitoes when compared to the salivary glands of males, and its