Development of Reliable, Valid and Responsive Scoring Systems for Endoscopy and Histology in Animal Models for Inflammatory Bowel Disease

Gut microbiota mediates the protective effects of β-hydroxybutyrate against cisplatin-induced acute kidney injury

The gut microbiota has been reported to be perturbed by chemotherapeutic agents and to modulate side effects. However, the critical role of β-hydroxybutyrate (BHB) in the regulation of the gut microbiota and the pathogenesis of chemotherapeutic agents related nephrotoxicity remains unknown. We conducted a comparative analysis of the composition and function of gut microbiota in healthy, cisplatin-challenged, BHB-treated, and high-fat diet-treated mice using 16 S rDNA gene sequencing. To understand the crucial involvement of intestinal flora in BHB's regulation of cisplatin -induced nephrotoxicity, we administered antibiotics to deplete the gut microbiota and performed fecal microbiota transplantation (FMT) before cisplatin administration. 16 S rDNA gene sequencing analysis demonstrated that both endogenous and exogenous BHB restored gut microbiota dysbiosis and cisplatin-induced intestinal barrier disruption in mice. Additionally, our findings suggested that the LPS/TLR4/NF-κB pathway was responsible for triggering renal inflammation in the gut-kidney axis. Furthermore, the ablation of the gut microbiota ablation using antibiotics eliminated the renoprotective effects of BHB against cisplatin-induced acute kidney injury. FMT also confirmed that administration of BHB-treated gut microbiota provided protection against cisplatin-induced nephrotoxicity. This study elucidated the mechanism by which BHB affects the gut microbiota mediation of cisplatin-induced nephrotoxicity by inhibiting the inflammatory response, which may help develop novel therapeutic approaches that target the composition of the microbiota.

LTβR-RelB signaling in intestinal epithelial cells protects from chemotherapy-induced mucosal damage

The intricate immune mechanisms governing mucosal healing following intestinal damage induced by cytotoxic drugs remain poorly understood. The goal of this study was to investigate the role of lymphotoxin beta receptor (LTβR) signaling in chemotherapy-induced intestinal damage. LTβR deficient mice exhibited heightened body weight loss, exacerbated intestinal pathology, increased proinflammatory cytokine expression, reduced IL-22 expression, and proliferation of intestinal epithelial cells following methotrexate (MTX) treatment. Furthermore, LTβR-/-IL-22-/- mice succumbed to MTX treatment, suggesting that LTβR- and IL-22- dependent pathways jointly promote mucosal repair. Although both LTβR ligands LIGHT and LTβ were upregulated in the intestine early after MTX treatment, LIGHT-/- mice, but not LTβ-/- mice, displayed exacerbated disease. Further, we revealed the critical role of T cells in mucosal repair as T cell-deficient mice failed to upregulate intestinal LIGHT expression and exhibited increased body weight loss and intestinal pathology. Analysis of mice with conditional inactivation of LTβR revealed that LTβR signaling in intestinal epithelial cells, but not in Lgr5+ intestinal stem cells, macrophages or dendritic cells was critical for mucosal repair. Furthermore, inactivation of the non-canonical NF-kB pathway member RelB in intestinal epithelial cells promoted MTX-induced disease. Based on these results, we propose a model wherein LIGHT produced by T cells activates LTβR-RelB signaling in intestinal epithelial cells to facilitate mucosal repair following chemotherapy treatment.

Banana Lectin: A Novel Immunomodulatory Strategy for Mitigating Inflammatory Bowel Disease

Compared to the general population, patients with inflammatory bowel disease (IBD) are less likely to be vaccinated, putting them at an increased risk of vaccine-preventable illnesses. This risk is further compounded by the immunosuppressive therapies commonly used in IBD management. Therefore, developing new treatments for IBD that maintain immune function is crucial, as successful management can lead to better vaccination outcomes and overall health for these patients. Here, we investigate the potential of recombinant banana lectin (rBanLec) as a supporting therapeutic measure to improve IBD control and possibly increase vaccination rates among IBD patients. By examining the therapeutic efficacy of rBanLec in a murine model of experimental colitis, we aim to lay the foundation for its application in improving vaccination outcomes. After inducing experimental colitis in C57BL/6 and BALB/c mice with 2,4,6-trinitrobenzene sulfonic acid, we treated animals orally with varying doses of rBanLec 0.1-10 µg/mL (0.01-1 µg/dose) during the course of the disease. We assessed the severity of colitis and rBanLec's modulation of the immune response compared to control groups. rBanLec administration resulted in an inverse dose-response reduction in colitis severity (less pronounced weight loss, less shortening of the colon) and an improved recovery profile, highlighting its therapeutic potential. Notably, rBanLec-treated mice exhibited significant modulation of the immune response, favoring anti-inflammatory pathways (primarily reduction in a local [TNFα]/[IL-10]) crucial for effective vaccination. Our findings suggest that rBanLec could mitigate the adverse effects of immunosuppressive therapy on vaccine responsiveness in IBD patients. By improving the underlying immune response, rBanLec may increase the efficacy of vaccinations, offering a dual benefit of disease management and prevention of vaccine-preventable illnesses. Further studies are required to translate these findings into clinical practice.

Inhibiting the cGAS-STING Pathway in Ulcerative Colitis with Programmable Micelles

Ulcerative colitis is a chronic condition in which a dysregulated immune response contributes to the acute intestinal inflammation of the colon. Current clinical therapies often exhibit limited efficacy and undesirable side effects. Here, programmable nanomicelles were designed for colitis treatment and loaded with RU.521, an inhibitor of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. STING-inhibiting micelles (SIMs) comprise hyaluronic acid-stearic acid conjugates and include a reactive oxygen species (ROS)-responsive thioketal linker. SIMs were designed to selectively accumulate at the site of inflammation and trigger drug release in the presence of ROS. Our in vitro studies in macrophages and in vivo studies in a murine model of colitis demonstrated that SIMs leverage HA-CD44 binding to target sites of inflammation. Oral delivery of SIMs to mice in both preventive and delayed therapeutic models ameliorated colitis's severity by reducing STING expression, suppressing the secretion of proinflammatory cytokines, enabling bodyweight recovery, protecting mice from colon shortening, and restoring colonic epithelium. In vivo end points combined with metabolomics identified key metabolites with a therapeutic role in reducing intestinal and mucosal inflammation. Our findings highlight the significance of programmable delivery platforms that downregulate inflammatory pathways at the intestinal mucosa for managing inflammatory bowel diseases.

Targeted delivery of the probiotic Saccharomyces boulardii to the extracellular matrix enhances gut residence time and recovery in murine colitis

Probiotic and engineered microbe-based therapeutics are an emerging class of pharmaceutical agents. They represent a promising strategy for treating various chronic and inflammatory conditions by interacting with the host immune system and/or delivering therapeutic molecules. Here, we engineered a targeted probiotic yeast platform wherein Saccharomyces boulardii is designed to bind to abundant extracellular matrix proteins found within inflammatory lesions of the gastrointestinal tract through tunable antibody surface display. This approach enabled an additional 24-48 h of probiotic gut residence time compared to controls and 100-fold increased probiotic concentrations within the colon in preclinical models of ulcerative colitis in female mice. As a result, pharmacodynamic parameters including colon length, colonic cytokine expression profiles, and histological inflammation scores were robustly improved and restored back to healthy levels. Overall, these studies highlight the potential for targeted microbial therapeutics as a potential oral dosage form for the treatment of inflammatory bowel diseases.

The emergence of inflammatory microglia during gut inflammation is not affected by FFAR2 expression in intestinal epithelial cells or peripheral myeloid cells

Gut inflammation can trigger neuroinflammation and is linked to mood disorders. Microbiota-derived short-chain fatty acids (SCFAs) can modulate microglia, yet the mechanism remains elusive. Since microglia do not express free-fatty acid receptor (FFAR)2, but intestinal epithelial cells (IEC) and peripheral myeloid cells do, we hypothesized that SCFA-mediated FFAR2 activation within the gut or peripheral myeloid cells may impact microglia inflammation. To test this hypothesis, we developed a tamoxifen-inducible conditional knockout mouse model targeting FFAR2 exclusively on IEC and induced intestinal inflammation with dextran sodium sulfate (DSS), a well-established colitis model. Given FFAR2's high expression in myeloid cells, we also investigated its role by selectively deleting it in these populations of cells. In an initial study, male and female wild-type mice received 0 or 2% DSS for 5d and microglia were isolated 3d later to assess inflammatory status. DSS induced intestinal inflammation and upregulated inflammatory gene expression in microglia, indicating inflammatory signaling via the gut-brain axis. Despite the lack of significant effects of sex in the intestinal phenotype, male mice showed higher microglial inflammatory response than females. Subsequent studies using FFAR2 knockout models revealed that FFAR2 expression in IECs or immune myeloid cells did not affect DSS-induced colonic pathology (i.e. clinical and histological scores and colon length), or colonic expression of inflammatory genes. However, FFAR2 knockout led to an upregulation of several microglial inflammatory genes in control mice and downregulation in DSS-treated mice, suggesting that FFAR2 may constrain neuroinflammatory gene expression under healthy homeostatic conditions but may permit it during intestinal inflammation. No interactions with sex were observed, suggesting sex does not play a role on FFAR2 potential function in gut-brain communication in the context of colitis. To evaluate the role of FFAR2 activated by microbiota-derived SCFAs, we employed the same knockout and DSS models adding fermentable dietary fiber (0 or 2.5% inulin for 8 wks). Despite no genotype or fiber main effects, contrary to our hypothesis, inulin feeding augmented DSS-induced inflammation and signs of colitis, suggesting context-dependent effects of fiber. These findings highlight microglial involvement in colitis-associated neuroinflammation and advance our understanding of FFAR2's role in the gut-brain axis. Although not integral, we observed that the role of FFAR2 differs between homeostatic and inflammatory conditions, underscoring the need to consider different inflammatory conditions and disease contexts when investigating the role of FFAR2 and SCFAs in the gut-brain axis.

WNT2B Deficiency Causes Enhanced Susceptibility to Colitis Due to Increased Inflammatory Cytokine Production

BACKGROUND & AIMS

Humans with WNT2B deficiency have severe intestinal disease, including significant inflammatory injury, highlighting a critical role for WNT2B. We sought to understand how WNT2B contributes to intestinal homeostasis.

METHODS

We investigated the intestinal health of Wnt2b knock out (KO) mice. We assessed the baseline histology and health of the small intestine and colon, and the impact of inflammatory challenge using dextran sodium sulfate (DSS). We also evaluated human intestinal tissue.

RESULTS

Mice with WNT2B deficiency had normal baseline histology but enhanced susceptibility to DSS colitis because of an increased early injury response. Although intestinal stem cells markers were decreased, epithelial proliferation was similar to control subjects. Wnt2b KO mice showed an enhanced inflammatory signature after DSS treatment. Wnt2b KO colon and human WNT2B-deficient organoids had increased levels of CXCR4 and IL6, and biopsy tissue from humans showed increased neutrophils.

CONCLUSIONS

WNT2B is important for regulation of inflammation in the intestine. Absence of WNT2B leads to increased expression of inflammatory cytokines and increased susceptibility to gastrointestinal inflammation, particularly in the colon.

Enterococcus durans 98D alters gut microbial composition and function to improve DSS-induced colitis in mice

Enterococcus durans, is a potential functional strain with the capacity to regulate intestinal health and ameliorate colonic inflammation. However, the strain requires further investigation regarding its safety profile and potential mechanisms of colitis improvement. In this study, the safety of E. durans 98D (Ed) as a potential probiotic was studied using in vitro methods. Additionally, a dextran sulfate sodium (DSS)-induced murine colitis model was employed to investigate its impact on the intestinal microbiota and colitis. In vitro antimicrobial assays revealed Ed sensitivity to common antibiotics and its inhibitory effect on the growth of Escherichia coli O157, Streptococcus pneumoniae CCUG 37328, and Staphylococcus aureus ATCC 25923. To elucidate the functional properties of Ed, 24 weight-matched 6-week-old female C57BL/6J mice were randomly divided into three groups (n = 8): NC group, Con group (DSS), and Ed group (DSS + Ed). Ed administration demonstrated a protective effect on colitis mice, as evidenced by improvements in body weight, colonic length, reduced disease activity index, histological scores, diminished splenomegaly, and decreased goblet cell loss. Furthermore, Ed downregulated the expression of the pro-inflammatory cytokine genes (IL-6, IL-1β, and TNF-α) and upregulated the expression of the anti-inflammatory cytokine gene IL-10. The 16S rRNA gene sequencing revealed significant alterations in microbial α-diversity, with principal coordinate analysis indicating distinct differences in microbial composition among the three groups. At the phylum level, the relative abundance of Actinomycetota significantly increased in the Ed-treated group. At the genus level, Ed treatment markedly elevated the relative abundance of Paraprevotella, Rikenellaceae_RC9, and Odoribacter in DSS-induced colitis mice. In conclusion, Ed exhibits potential as a safe and effective therapeutic agent for DSS-induced colitis by reshaping the colonic microbiota.

Discovery of Clinical Candidate GLPG3970: A Potent and Selective Dual SIK2/SIK3 Inhibitor for the Treatment of Autoimmune and Inflammatory Diseases

The salt-inducible kinases (SIKs) SIK1, SIK2, and SIK3 belong to the adenosine monophosphate-activated protein kinase (AMPK) family of serine/threonine kinases. SIK inhibition represents a new therapeutic approach modulating pro-inflammatory and immunoregulatory pathways that holds potential for the treatment of inflammatory diseases. Here, we describe the identification of GLPG3970 (32), a first-in-class dual SIK2/SIK3 inhibitor with selectivity against SIK1 (IC50 of 282.8 nM on SIK1, 7.8 nM on SIK2 and 3.8 nM on SIK3). We outline efforts made to increase selectivity against SIK1 and improve CYP time-dependent inhibition properties through the structure-activity relationship. The dual activity of 32 in modulating the pro-inflammatory cytokine TNFα and the immunoregulatory cytokine IL-10 is demonstrated in vitro in human primary myeloid cells and human whole blood, and in vivo in mice stimulated with lipopolysaccharide. Compound 32 shows dose-dependent activity in disease-relevant mouse pharmacological models.

A Pro-Regenerative Supramolecular Prodrug Protects Against and Repairs Colon Damage in Experimental Colitis

Structural repair of the intestinal epithelium is strongly correlated with disease remission in inflammatory bowel disease (IBD); however, ulcer healing is not addressed by existing therapies. To address this need, this study reports the use of a small molecule prolyl hydroxylase (PHD) inhibitor (DPCA) to upregulate hypoxia-inducible factor one-alpha (HIF-1α) and induce mammalian regeneration. Sustained delivery of DPCA is achieved through subcutaneous injections of a supramolecular hydrogel, formed through the self-assembly of PEG-DPCA conjugates. Pre-treatment of mice with PEG-DPCA is shown to protect mice from epithelial erosion and symptoms of dextran sodium sulfate (DSS)-induced colitis. Surprisingly, a single subcutaneous dose of PEG-DPCA, administered after disease onset, leads to accelerated weight gain and complete restoration of healthy tissue architecture in colitic mice. Rapid DPCA-induced restoration of the intestinal barrier is likely orchestrated by increased expression of HIF-1α and associated targets leading to an epithelial-to-mesenchymal transition. Further investigation of DPCA as a potential adjunctive or stand-alone restorative treatment to combat active IBD is warranted.

Retinoid orphan receptor gamma t (rorγt) promotes inflammatory eosinophilia but is dispensable for innate immune-mediated colitis

Inflammatory bowel diseases (IBD) result from uncontrolled inflammation in the intestinal mucosa leading to damage and loss of function. Both innate and adaptive immunity contribute to the inflammation of IBD and innate and adaptive immune cells reciprocally activate each other in a forward feedback loop. In order to better understand innate immune contributions to IBD, we developed a model of spontaneous 100% penetrant, early onset colitis that occurs in the absence of adaptive immunity by crossing villin-TNFAIP3 mice to RAG1-/- mice (TRAG mice). This model is driven by microbes and features increased levels of innate lymphoid cells in the intestinal mucosa. To investigate the role of type 3 innate lymphoid cells (ILC3) in the innate colitis of TRAG mice, we crossed them to retinoid orphan receptor gamma t deficient (Rorγt-/-) mice. Rorγt-/- x TRAG mice exhibited markedly reduced eosinophilia in the colonic mucosa, but colitis persisted in these mice. Colitis in Rorγt-/- x TRAG mice was characterized by increased infiltration of the intestinal mucosa by neutrophils, inflammatory monocytes, macrophages and other innate cells. RNA and cellular profiles of Rorγt-/- x TRAG mice were consistent with a lack of ILC3 and ILC3 derived cytokines, reduced antimicrobial factors, increased activation oof epithelial repair processes and reduced activation of epithelial cell STAT3. The colitis in Rorγt-/- x TRAG mice was ameliorated by antibiotic treatment indicating that microbes contribute to the ILC3-independent colitis of these mice. Together, these gene expression and cell signaling signatures reflect the double-edged sword of ILC3 in the intestine, inducing both proinflammatory and antimicrobial protective responses. Thus, Rorγt promotes eosinophilia but Rorγt and Rorγt-dependent ILC3 are dispensable for the innate colitis in TRAG mice.

The UDP-glucose/P2Y14 receptor axis promotes eosinophil-dependent large intestinal inflammation

Ulcerative colitis (UC) is a chronic disorder of the large intestine with inflammation and ulceration. The incidence and prevalence of UC have been rapidly increasing worldwide, but its etiology remains unknown. In patients with UC, the accumulation of eosinophils in the large intestinal mucosa is associated with increased disease activity. However, the molecular mechanism underlying the promotion of intestinal eosinophilia in patients with UC remains poorly understood. Here, we show that uridine diphosphate (UDP)-glucose mediates the eosinophil-dependent promotion of colonic inflammation via the purinergic receptor P2Y14. The expression of P2RY14 mRNA was upregulated in the large intestinal mucosa of patients with UC. The P2Y14 receptor ligand UDP-glucose was increased in the large intestinal tissue of mice administered dextran sodium sulfate (DSS). In addition, P2ry14 deficiency and P2Y14 receptor blockade mitigated DSS-induced colitis. Among the large intestinal immune cells and epithelial cells, eosinophils highly expressed P2ry14 mRNA. P2ry14-/- mice transplanted with wild-type bone marrow eosinophils developed more severe DSS-induced colitis compared with P2ry14-/- mice that received P2ry14-deficient eosinophils. UDP-glucose prolonged the lifespan of eosinophils and promoted gene transcription in the cells through P2Y14 receptor-mediated activation of ERK1/2 signaling. Thus, the UDP-glucose/P2Y14 receptor axis aggravates large intestinal inflammation by accelerating the accumulation and activation of eosinophils.

Investigation of Gastrointestinal Toxicities Associated with Concurrent Abdominal Radiation Therapy and the Tyrosine Kinase Inhibitor Sunitinib in a Mouse Model

Tyrosine kinase inhibitors (TKIs) may be combined with radiation therapy (RT) to enhance tumor control; however, increased incidences of gastrointestinal (GI) toxicity have been reported with this combination. We hypothesize that toxicity is due to compromised intestinal healing caused by inhibition of vascular repair and proliferation pathways. This study explores underlying tissue toxicity associated with abdominal RT and concurrent sunitinib in a mouse model. Four groups of CD-1 mice were treated with 12 Gy abdominal RT, oral sunitinib, abdominal RT + sunitinib, or sham treatment. Mice received oral sunitinib or the vehicle via gavage for 14 days. On day 7, mice were irradiated with 12 Gy abdominal RT or sham treated. Mice were euthanized on day 14 and intestinal tract was harvested for semiquantitative histopathologic evaluation and immunohistochemical quantification of proliferation (Ki67) and vascular density (CD31). Non-irradiated groups had stable weights while abdominal irradiation resulted in weight loss, with mice receiving RT + SUN having greater weight loss than mice receiving RT alone. Semiquantitative analysis showed significant increases in inflammation in irradiated groups. The difference in the density of CD31+ cells was significantly increased in RT alone compared to SUN alone. Ki67+ density was not significant. In summary, we identify a lack of angiogenic response in irradiated GI tissues when abdominal RT is combined with a TKI, which may correlate with clinical toxicities seen in canine and human patients receiving combined treatment.

A nanoparticle platform for combined mucosal healing and immunomodulation in inflammatory bowel disease treatment

Current treatments for inflammatory bowel disease (IBD) treatment consist of anti-inflammatory products. In this study, we sought to induce the physiological secretion of glucagon-like peptide 2, a peptide with intestinal growth-promoting activity, via nanoparticles while simultaneously providing with immunomodulation by tailoring the nanoparticle surface. To this end, we developed hybrid lipid hyaluronate-KPV conjugated nanoparticles loaded with teduglutide for combination therapy in IBD. The nanocarriers induced (or did not induce) immunosuppression depending on the presence (or absence) of a hyaluronan-KPV functionalization. This strategy holds promise as a nanoparticle platform for combined mucosal healing and immunomodulation in IBD treatment.

Optogenetic Activation of Cholinergic Enteric Neurons Reduces Inflammation in Experimental Colitis

BACKGROUND & AIMS

Intestinal inflammation is associated with loss of enteric cholinergic neurons. Given the systemic anti-inflammatory role of cholinergic innervation, we hypothesized that enteric cholinergic neurons similarly possess anti-inflammatory properties and may represent a novel target to treat inflammatory bowel disease.

METHODS

Mice were fed 2.5% dextran sodium sulfate (DSS) for 7 days to induce colitis. Cholinergic enteric neurons, which express choline acetyltransferase (ChAT), were focally ablated in the midcolon of ChAT::Cre;R26-iDTR mice by local injection of diphtheria toxin before colitis induction. Activation of enteric cholinergic neurons was achieved using ChAT::Cre;R26-ChR2 mice, in which ChAT+ neurons express channelrhodopsin-2, with daily blue light stimulation delivered via an intracolonic probe during the 7 days of DSS treatment. Colitis severity, ENS structure, and smooth muscle contractility were assessed by histology, immunohistochemistry, quantitative polymerase chain reaction, organ bath, and electromyography. In vitro studies assessed the anti-inflammatory role of enteric cholinergic neurons on cultured muscularis macrophages.

RESULTS

Ablation of ChAT+ neurons in DSS-treated mice exacerbated colitis, as measured by weight loss, colon shortening, histologic inflammation, and CD45+ cell infiltration, and led to colonic dysmotility. Conversely, optogenetic activation of enteric cholinergic neurons improved colitis, preserved smooth muscle contractility, protected against loss of cholinergic neurons, and reduced proinflammatory cytokine production. Both acetylcholine and optogenetic cholinergic neuron activation in vitro reduced proinflammatory cytokine expression in lipopolysaccharide-stimulated muscularis macrophages.

CONCLUSIONS

These findings show that enteric cholinergic neurons have an anti-inflammatory role in the colon and should be explored as a potential inflammatory bowel disease treatment.

MAdCAM-1 targeting strategy can prevent colitic cancer carcinogenesis and progression via suppression of immune cell infiltration and inflammatory signals

Chronic inflammation caused by infiltrating immune cells can promote colitis-associated dysplasia/colitic cancer in ulcerative colitis (UC) by activating inflammatory cytokine signalling through the IL-6/p-STAT3 and TNFα/NF-κB pathways. Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) expressed on high endothelial venules promotes the migration of immune cells from the bloodstream to the gut via interaction with α4β7 integrin expressed on the immune cells. MAdCAM-1, has therefore drawn interest as a novel therapeutic target for treating active UC. However, the role of MAdCAM-1-positive endothelial cells in immune cell infiltration in dysplasia/colitic cancers remains unclear. We evaluated the expression of MAdCAM-1, CD31 and immune cell markers (CD8, CD68, CD163 and FOXP3) in samples surgically resected from 11 UC patients with dysplasia/colitic cancer and 17 patients with sporadic colorectal cancer (SCRC), using immunohistochemical staining. We used an azoxymethane/dextran sodium sulphate mouse model (AOM/DSS mouse) to evaluate whether dysplasia/colitic cancer could be suppressed with an anti-MAdCAM-1 blocking antibody by preventing immune cell infiltration. The number of MAdCAM-1-positive vessels and infiltrating CD8+ , CD68+ and CD163+ immune cells was significantly higher in dysplasia/colitic cancer than in normal, SCRC and UC mucosa. In AOM/DSS mice, the anti-MAdCAM-1 antibody reduced the number, mean diameter, depth of tumours, Ki67 positivity, number of CD8+ , CD68+ and CD163+ immune cells and the IL-6/p-STAT3 and TNF-α/NF-κB signalling. Our results indicate that targeting MAdCAM-1 is a promising strategy for controlling not only UC severity but also carcinogenesis and tumour progression by regulating inflammation/immune cell infiltration in patients with UC.

Macrophage polarization toward M1 phenotype in T cell transfer colitis model

BACKGROUND

T cell transfer colitis model is often used to study the CD4+ T cell functions in the intestine. However, the specific roles of macrophages in colitis remain unclear. In this study, we aimed to evaluate the phenotype and functions of macrophages in the colonic lamina propria (LP) in a colitis model.

METHODS

Colitis was induced in scid mice via the adaptive transfer of CD4+CD45RBhi T cells. Then, flow cytometry was used to determine the number of macrophages in the colonic LP and expression of cytokines in macrophages at the onset of colitis. Moreover, M1/M2 macrophage markers were detected in the colonic LP during colitis development using high-dimensional single-cell data and gating-based analyses. Expression levels of M1 markers in macrophages isolated from the colonic LP were measured using quantitative reverse transcription-polymerase chain reaction. Additionally, macrophages were co-cultured with T cells isolated from the colon to assess colitogenic T cell activation.

RESULTS

Infiltration of macrophages into the colon increased with the development of colitis in the T cell transfer colitis model. M1/M2 macrophage markers were observed in this model, as observed in the colon of patients with inflammatory bowel disease (IBD). Moreover, number of M1 macrophages increased, whereas that of M2 macrophages decreased in the colonic LP during colitis development. M1 macrophages were identified as the main source of inflammatory cytokine production, and colitogenic T cells were activated via interactions with these macrophages.

CONCLUSIONS

Our findings revealed that macrophages polarized toward the M1 phenotype in LP during colitis development in the T cell transfer colitis model. Therefore, the colitis model is suitable for the evaluation of the efficacy of macrophage-targeted drugs in human IBD treatment. Furthermore, this model can be used to elucidate the in vivo functions of macrophages in the colon of patients with IBD.

Identification of omega-3 oxylipins in human milk-derived extracellular vesicles with pro-resolutive actions in gastrointestinal inflammation

Introduction

Premature infants (PIs) are at risk of suffering necrotizing enterocolitis (NEC), and infants consuming human milk (HM) show a lower incidence than infants receiving formula. The composition of HM has been studied in depth, but the lipid content of HM-derived small extracellular vesicles (HM sEVs) remains unexplored. Identifying these molecules and their biological effects has potential for the treatment of intestinal disorders in PIs and could contribute to the development of HM-based fortified formulas.

Methods

We isolated HM sEVs from HM samples and analyzed their oxylipin content using liquid chromatography coupled to mass spectrometry, which revealed the presence of anti-inflammatory oxylipins. We then examined the efficacy of a mixture of these oxylipins in combating inflammation and fibrosis, in vitro and in a murine model of inflammatory bowel disease (IBD).

Results

HM-related sEVs contained higher concentrations of oxylipins derived from docosahexaenoic acid, an omega-3 fatty acid. Three anti-inflammatory oxylipins, 14-HDHA, 17-HDHA, and 19,20-DiHDPA (ω3 OXLP), demonstrated similar efficacy to HM sEVs in preventing cell injury, inducing re-epithelialization, mitigating fibrosis, and modulating immune responses. Both ω3 OXLP and HM sEVs effectively reduced inflammation in IBD-model mice, preventing colon shortening, infiltration of inflammatory cells and tissue fibrosis.

Discussion

Incorporating this unique cocktail of oxylipins into fortified milk formulas might reduce the risk of NEC in PIs and also provide immunological and neurodevelopmental support.

Thiostrepton alleviates experimental colitis by promoting RORγt ubiquitination and modulating dysbiosis

Thiostrepton (TST) is a natural antibiotic with pleiotropic properties. This study aimed to elucidate the therapeutic effect of TST on experimental colitis and identify its targets. The effect of TST on colon inflammation was evaluated in a dextran sulfate sodium (DSS)-induced colitis model and a T-cell transfer colitis model. The therapeutic targets of TST were investigated by cytokine profiling, immunophenotyping and biochemical approaches. The effect of TST on the gut microbiota and its contribution to colitis were evaluated in mice with DSS-induced colitis that were subjected to gut microbiota depletion and fecal microbiota transplantation (FMT). Alterations in the gut microbiota caused by TST were determined by 16S rDNA and metagenomic sequencing. Here, we showed that TST treatment significantly ameliorated colitis in the DSS-induced and T-cell transfer models. Specifically, TST targeted the retinoic acid-related orphan nuclear receptor RORγt to reduce the production of IL-17A by γδ T cells, type 3 innate lymphoid cells (ILC3s) and Th17 cells in mice with DSS-induced colitis. Similarly, TST selectively prevented the development of Th17 cells in the T-cell transfer colitis model and the differentiation of naïve CD4+ T cells into Th17 cells in vitro. Mechanistically, TST induced the ubiquitination and degradation of RORγt by promoting the binding of Itch to RORγt. Moreover, TST also reversed dysbiosis to control colonic inflammation. Taken together, these results from our study describe the previously unexplored role of TST in alleviating colonic inflammation by reducing IL-17A production and modulating dysbiosis, suggesting that TST is a promising candidate drug for the treatment of IBD.

The arginine methyltransferase PRMT5 promotes mucosal defense in the intestine

PRMT5 is a type II arginine methyltransferase abundantly expressed in the colonic epithelium. It is up-regulated in inflammatory bowel disease and colorectal cancer. However, its role in mucosal defense against enteric infection has not been studied. Here, we report that Prmt5 in the murine colon is up-regulated in response to Citrobacter rodentium infection. Pathogen clearance in mice with haploinsufficient expression of Prmt5 is significantly delayed compared with wildtype littermate controls. Transcriptomic analyses further reveal that PRMT5 regulates the expression of canonical crypt goblet cell genes involved in mucus production, assembly, and anti-microbial responses via methyltransferase activity-dependent and -independent mechanisms. Together, these findings uncover PRMT5 as a novel regulator of mucosal defense and a potential therapeutic target for treating intestinal diseases.

Rationally-defined microbial consortia suppress multidrug-resistant proinflammatory Enterobacteriaceae via ecological control

Persistent colonization and outgrowth of pathogenic organisms in the intestine may occur due to long-term antibiotic usage or inflammatory conditions, which perpetuate dysregulated immunity and tissue damage1,2. Gram-negative Enterobacteriaceae gut pathobionts are particularly recalcitrant to conventional antibiotic treatment3,4, though an emerging body of evidence suggests that manipulation of the commensal microbiota may be a practical alternative therapeutic strategy5-7. In this study, we rationally isolated and down-selected commensal bacterial consortia from healthy human stool samples capable of strongly and specifically suppressing intestinal Enterobacteriaceae. One of the elaborated consortia, consisting of 18 commensal strains, effectively controlled ecological niches by regulating gluconate availability, thereby reestablishing colonization resistance and alleviating antibiotic-resistant Klebsiella-driven intestinal inflammation in mice. Harnessing these microbial activities in the form of live bacterial therapeutics may represent a promising solution to combat the growing threat of proinflammatory, antimicrobial-resistant bacterial infection.

Modulation of the Gut Microbiota by the Plantaricin-Producing Lactiplantibacillus plantarum D13, Analysed in the DSS-Induced Colitis Mouse Model

Lactiplantibacillus plantarum D13 shows antistaphylococcal and antilisterial activity, probably due to the synthesis of a presumptive bacteriocin with antibiofilm capacity released in the cell-free supernatant (CFS), whose inhibitory effect is enhanced by cocultivation with susceptible strains. An in silico analysis of the genome of strain D13 confirmed the pln gene cluster. Genes associated with plantaricin biosynthesis, structure, transport, antimicrobial activity, and immunity of strain D13 were identified. Furthermore, the predicted homology-based 3D structures of the cyclic conformation of PlnE, PlnF, PlnJ, and PlnK revealed that PlnE and PlnK contain two helices, while PlnF and PlnJ contain one and two helices, respectively. The potential of the strain to modulate the intestinal microbiota in healthy or dextran sulphate sodium (DSS)-induced colitis mouse models was also investigated. Strain D13 decreased the disease activity index (DAI) and altered the gut microbiota of mice with DSS-induced colitis by increasing the ratio of beneficial microbial species (Allobaculum, Barnesiella) and decreasing those associated with inflammatory bowel disease (Candidatus Saccharimonas). This suggests that strain D13 helps to restore the gut microbiota after DSS-induced colitis, indicating its potential for further investigation as a probiotic strain for the prevention and treatment of colitis.

Radiofrequency ablation via an implanted self-expandable metallic stent to treat in-stent restenosis in a rat gastric outlet obstruction model

Background: In-stent restenosis caused by tissue hyperplasia and tumor growth through the wire meshes of an implanted self-expandable metallic stent (SEMS) remains an unresolved obstacle. This study aimed to investigate the safety and efficacy of SEMS-mediated radiofrequency ablation (RFA) for treating stent-induced tissue hyperplasia in a rat gastric outlet obstruction model. Methods: The ablation zone was investigated using extracted porcine liver according to the ablation time. The optimal RFA parameters were evaluated in the dissected rat gastric outlet. We allocated 40 male rats to four groups of 10 rats as follows: group A, SEMS placement only; group B, SEMS-mediated RFA at 4 weeks; group C, SEMS-mediated RFA at 4 weeks and housed until 8 weeks; and group D, SEMS-mediated RFA at 4 and 8 weeks. Endoscopy and fluoroscopy for in vivo imaging and histological and immunohistochemical analysis were performed to compare experimental groups. Results: Stent placement and SEMS-mediated RFA with an optimized RFA parameter were technically successful in all groups. Granulation tissue formation-related variables were significantly higher in group A than in groups B-D (all p < 0.05). Endoscopic and histological findings confirmed that the degrees of stent-induced tissue hyperplasia in group D were significantly lower than in groups B and C (all p < 0.05). Hsp70 and TUNEL expressions were significantly higher in groups B-D than in group A (all p < 0.001). Conclusion: The implanted SEMS-mediated RFA successfully managed stent-induced tissue hyperplasia, and repeated or periodic RFA seems to be more effective in treating in-stent restenosis in a rat gastric outlet obstruction model.

The synergistic mechanism of action of Dajianzhong decoction in conjunction with ketamine in the treatment of depression

Depression is a multifactorial syndrome with a variety of underlying pathological mechanisms. While ketamine, an N-methyl-D-aspartate receptor (NMDAR) antagonist, exhibits a rapid antidepressant action in the central never system (CNS), the potential addiction and psychotomimetic adverse effects of ketamine limit its chronic use in clinical practice. Therefore, it is necessary to discover an additional agent that shows a synergistic antidepressant activity with ketamine to sustain its therapeutic action so as to reduce its use frequency in depression treatment. The present study indicated that Dajianzhong decoction (DJZT), an empirical herbal formula used for the clinical treatment of several inflammation-related intestinal disorders, sustains behavioral and synaptic action of ketamine in depressive mouse models. Additionally, ketamine was also demonstrated to exert a synergistic action with DJZT to alleviate the chronic unpredictable mild stress (CUMS)-induced abnormalities in gut barrier proteins and colonic histology, and subsequently to normalize the diversity and composition of gut microbiota. Furthermore, DJZT was shown to possess an anti-inflammatory activity to prevent activation of NF-κB from releasing proinflammatory cytokines, specifically through inhibiting Th17 cells/IL-17A pathway. Our results uncovered the mechanism of action of DJZT in conjunction with ketamine in depression treatment by which these agents target different pathological factors across biological systems and exert a synergistic activity through a bidirectional communication in the gut-brain axis, and also provided new insights into the systematic treatment of depression.

Hepatobiliary manganese homeostasis is dynamic in the setting of inflammation or infection in mice

Manganese is a diet-derived micronutrient that is essential for critical cellular processes like redox homeostasis, protein glycosylation, and lipid and carbohydrate metabolism. Control of Mn availability, especially at the local site of infection, is a key component of the innate immune response. Less has been elucidated about Mn homeostasis at the systemic level. In this work, we demonstrate that systemic Mn homeostasis is dynamic in response to inflammation and infection in mice. This phenomenon is evidenced in male and female mice, mice of two genetic backgrounds (C57BL/6 and BALB/c), in multiple models of acute (dextran sodium sulfate-induced) and chronic (enterotoxigenic Bacteroides fragilis) colitis, and systemic infection with Candida albicans. When mice were fed a standard corn-based chow with excess Mn (100 ppm), liver Mn decreased and biliary Mn increased threefold in response to infection or colitis. Liver iron, copper, and zinc were unchanged. When dietary Mn was restricted to minimally adequate amounts (10 ppm), baseline hepatic Mn levels decreased by approximately 60% in the liver, and upon induction of colitis, liver Mn did not decrease further, however, biliary Mn still increased 20-fold. In response to acute colitis, hepatic Slc39a8 mRNA (gene encoding the Mn importer, Zip8) and Slc30a10 mRNA (gene encoding the Mn exporter, Znt10) are decreased. Zip8 protein is decreased. Inflammation/infection-associated dynamic Mn homeostasis may represent a novel host immune/inflammatory response that reorganizes systemic Mn availability through differential expression of key Mn transporters with down-regulation of Zip8.

Bacteroides uniformis-induced perturbations in colonic microbiota and bile acid levels inhibit TH17 differentiation and ameliorate colitis developments

Inflammatory bowel disease (IBD) is associated with gut dysbiosis and can lead to colitis-associated malignancies. Bacteroides uniformis (Bu) regulates animal intestinal homeostasis; however, the mechanism by which it alleviates colitis in mice remains unknown. We investigated the effects of B. uniformis JCM5828 and its metabolites on female C57BL/6J mice with dextran sulfate sodium salt (DSS) induced colitis. Treatment with Bu considerably alleviated colitis progression and restored the mechanical and immune barrier protein expression. Additionally, Bu increased the abundance of the symbiotic bacteria Bifidobacterium and Lactobacillus vaginalis while decreasing that of pathogenic Escherichia-Shigella, and modulated intestinal bile acid metabolism. Bu largely regulated the expression of key regulatory proteins of the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways in colonic tissues and the differentiation of TH17 cells. However, Bu could not directly inhibit TH17 cell differentiation in vitro; it modulated the process in the lamina propria by participating in bile acid metabolism and regulating key metabolites (alpha-muricholic, hyodeoxycholic, and isolithocholic acid), thereby modulating the intestinal immune response. Our findings suggest that Bu or bile acid supplements are potential therapies for colitis and other diseases associated with intestinal barrier dysfunction.

Commensal Escherichia coli Strains of Bovine Origin Competitively Mitigated Escherichia coli O157:H7 in a Gnotobiotic Murine Intestinal Colonization Model with or without Physiological Stress

Cattle are a primary reservoir of enterohemorrhagic Escherichia coli (EHEC) O157:H7. Currently, there are no effective methods of eliminating this important zoonotic pathogen from cattle, and colonization resistance in relation to EHEC O157:H7 in cattle is poorly understood. We developed a gnotobiotic EHEC O157:H7 murine model to examine aspects of the cattle pathogen-microbiota interaction, and to investigate competitive suppression of EHEC O157:H7 by 18 phylogenetically distinct commensal E. coli strains of bovine origin. As stress has been suggested to influence enteric colonization by EHEC O157:H7 in cattle, corticosterone administration (±) to incite a physiological stress response was included as an experimental variable. Colonization of the intestinal tract (IT) of mice by the bovine EHEC O157:H7 strain, FRIK-2001, mimicked characteristics of bovine IT colonization. In this regard, FRIK-2001 successfully colonized the IT and temporally incited minimal impacts on the host relative to other EHEC O157:H7 strains, including on the renal metabolome. The presence of the commensal E. coli strains decreased EHEC O157:H7 densities in the cecum, proximal colon, and distal colon. Moreover, histopathologic changes and inflammation markers were reduced in the distal colon of mice inoculated with commensal E. coli strains (both propagated separately and communally). Although stress induction affected the behavior of mice, it did not influence EHEC O157:H7 densities or disease. These findings support the use of a gnotobiotic murine model of enteric bovine EHEC O157:H7 colonization to better understand pathogen-host-microbiota interactions toward the development of effective on-farm mitigations for EHEC O157:H7 in cattle, including the identification of bacteria capable of competitively colonizing the IT.

A novel murine model of pyoderma gangrenosum reveals that inflammatory skin-gut crosstalk is mediated by IL-1β-primed neutrophils

Pyoderma gangrenosum (PG) is a debilitating skin condition often accompanied by inflammatory bowel disease (IBD). Strikingly, ~40% of patients that present with PG have underlying IBD, suggesting shared but unknown mechanisms of pathogenesis. Impeding the development of effective treatments for PG is the absence of an animal model that exhibits features of both skin and gut manifestations. This study describes the development of the first experimental drug-induced mouse model of PG with concomitant intestinal inflammation. Topical application of pyrimidine synthesis inhibitors on wounded mouse skin generates skin ulcers enriched in neutrophil extracellular traps (NETs) as well as pro-inflammatory cellular and soluble mediators mimicking human PG. The mice also develop spontaneous intestinal inflammation demonstrated by histologic damage. Further investigations revealed increased circulating low density IL-1β primed neutrophils that undergo enhanced NETosis at inflamed tissue sites supported by an increase in circulatory citrullinated histone 3, a marker of aberrant NET formation. Granulocyte depletion dampens the intestinal inflammation in this model, further supporting the notion that granulocytes contribute to the skin-gut crosstalk in PG mice. We anticipate that this novel murine PG model will enable researchers to probe common disease mechanisms and identify more effective targets for treatment for PG patients with IBD.

Ionically bridged dexamethasone sodium phosphate-zinc-PLGA nanocomplex in alginate microgel for the local treatment of ulcerative colitis

Colon-targeted oral drug delivery systems comprising nanoparticles and microparticles have emerged as promising tools for the treatment of ulcerative colitis (UC) because they minimize side effects and maximize the local drug concentration. Dexamethasone sodium phosphate (DSP) is a potent anti-inflammatory glucocorticoid used for the treatment of UC. However, it remains a rather short-term treatment option owing to its side effects. In the present study, we developed the alginate gel encapsulating ionically bridged DSP-zinc-poly(lactic-co-glycolic acid) (PLGA) nanocomplex (DZP-NCs-in-microgel) for the oral local treatment of UC. The successful encapsulation of DSP-zinc-PLGA nanocomplex (DZP-NCs) in alginate microgel was confirmed by SEM imaging. The prepared gel released DZP-NCs in the stimulated intestinal fluid and dampened the release of DSP in the upper gastrointestinal tract. Furthermore, DZP-NCs-in-microgel alleviated colonic inflammation in a mouse model of dextran sodium sulfate-induced colitis by relieving clinical symptoms and histological marks. Our results suggest a novel approach for the oral colon-targeted delivery of dexamethasone sodium phosphate for the treatment of UC.

Effects of an inulin fiber diet on the gut microbiome, colon, and inflammatory biomarkers in aged mice

Due to the increasing human life expectancy and limited supply of healthcare resources, strategies to promote healthy aging and reduce associated functional deficits are of public health importance. The gut microbiota, which remodels with age, has been identified as a significant contributor to the aging process that is modifiable by diet. Since prebiotic dietary components such as inulin have been shown to impart positive benefits with regards to aging, this study used C57Bl6 mice to investigate whether 8 weeks on a 2.5 % inulin enhanced AIN-93M 1 % cellulose diet could offset age-associated changes in gut microbiome composition and markers of colon health and systemic inflammation in comparison to a AIN 93M 1 % cellulose diet with 0 % inulin. Our results demonstrated that, in both age groups, dietary inulin significantly increased production of butyrate in the cecum and induced changes in the community structure of the gut microbiome but did not significantly affect systemic inflammation or other markers of gastrointestinal health. Aged mice had different and less diverse microbiomes when compared to adult mice and were less sensitive to inulin-induced microbiome community shifts, evidenced by longitudinal differences in differentially abundant taxa and beta diversity. In aged mice, inulin restored potentially beneficial taxa including Bifidobacterium and key butyrate producing genera (e.g. Faecalibaculum). Despite inducing notable taxonomic changes, however, the 2.5 % inulin diet reduced alpha diversity in both age groups and failed to reduce overall community compositional differences between age groups. In conclusion, a 2.5 % inulin enhanced diet altered gut microbiome α and β diversity, composition, and butyrate production in both adult and aged mice, with more potent effects on β diversity and greater number of taxa significantly altered in adult mice. However, significant benefits in age-associated changes in systemic inflammation or intestinal outcomes were not detected.

Network pharmacology-based identification of bioavailable anti-inflammatory agents from Psoralea corylifolia L. in an experimental colitis model

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional oriental medicine, the dried seeds of Psoralea corylifolia L. (PC) have been used to treat various diseases, including gastrointestinal, urinary, orthopedic, diarrheal, ulcer, and inflammatory disorders.

AIM OF THE STUDY

Although its various biological properties are well-known, there is no information on the therapeutic effects and bioavailable components of PC against inflammatory bowel disease. Therefore, we focused on the relationship between hydroethanolic extract of PC (EPC) that ameliorates colitis in mice and bioactive constituents of EPC that suppress pro-inflammatory cytokines in macrophages.

MATERIALS AND METHODS

We investigated the therapeutic effects of EPC in a dextran sulfate sodium-induced colitis mouse model and identified the orally absorbed components of EPC using UPLC-MS/MS analysis. In addition, we evaluated and validated the mechanism of action of the bioavailable constituents of EPC using network pharmacology analysis. The effects on nitric oxide (NO) and inflammatory cytokines were measured by Griess reagent and enzyme linked immunosorbent assay in lipopolysaccharide (LPS)-induced macrophages.

RESULTS

In experimental colitis, EPC improved body weight loss, colon length shortening, and disease activity index. Moreover, EPC reduced the serum levels of pro-inflammatory cytokines and histopathological damage to the colon. Network pharmacological analysis identified 13 phytochemicals that were bioavailable following oral administration of EPC, as well as their potential anti-inflammatory effects. 11 identified EPC constituents markedly reduced the overproduction of NO, tumor necrosis factor-α, and/or interleukin-6 in macrophages induced by LPS. The LPS-induced expression of the nuclear factor kappa-light-chain-enhancer of activated B cells reporter gene was reduced by the 4 EPC constituents.

CONCLUSIONS

The results indicate that the protective activity of EPC against colitis is a result of the additive effects of each constituent on the expression of inflammatory cytokines. Therefore, it suggests that 11 bioavailable phytochemicals of EPC could aid in the management of intestinal inflammation, and also provides useful insights into the clinical application of PC for the treatment of inflammatory bowel diseases.

WNT2B Deficiency Causes Increased Susceptibility to Colitis in Mice and Impairs Intestinal Epithelial Development in Humans

Background and aims

WNT2B is a canonical Wnt ligand previously thought to be fully redundant with other Wnts in the intestinal epithelium. However, humans with WNT2B deficiency have severe intestinal disease, highlighting a critical role for WNT2B. We sought to understand how WNT2B contributes to intestinal homeostasis.

Methods

We investigated the intestinal health of Wnt2b knock out (KO) mice. We assessed the impact of inflammatory challenge to the small intestine, using anti-CD3χ antibody, and to the colon, using dextran sodium sulfate (DSS). In addition, we generated human intestinal organoids (HIOs) from WNT2B-deficient human iPSCs for transcriptional and histological analyses.

Results

Mice with WNT2B deficiency had significantly decreased Lgr5 expression in the small intestine and profoundly decreased expression in the colon, but normal baseline histology. The small intestinal response to anti-CD3χ antibody was similar in Wnt2b KO and wild type (WT) mice. In contrast, the colonic response to DSS in Wnt2b KO mice showed an accelerated rate of injury, featuring earlier immune cell infiltration and loss of differentiated epithelium compared to WT. WNT2B-deficient HIOs showed abnormal epithelial organization and an increased mesenchymal gene signature.

Conclusion

WNT2B contributes to maintenance of the intestinal stem cell pool in mice and humans. WNT2B deficient mice, which do not have a developmental phenotype, show increased susceptibility to colonic injury but not small intestinal injury, potentially due to a higher reliance on WNT2B in the colon compared to the small intestine.WNT2B deficiency causes a developmental phenotype in human intestine with HIOs showing a decrease in their mesenchymal component and WNT2B-deficient patients showing epithelial disorganization.

Data Transparency Statement

All RNA-Seq data will be available through online repository as indicated in Transcript profiling. Any other data will be made available upon request by emailing the study authors.

Hepatobiliary manganese homeostasis is dynamic in the setting of illness in mice

Manganese is a diet-derived micronutrient that is essential for critical cellular processes like redox homeostasis, protein glycosylation, and lipid and carbohydrate metabolism. Control of Mn availability, especially at the local site of infection, is a key component of the innate immune response. Less has been elucidated about Mn homeostasis at the systemic level. In this work, we demonstrate that systemic Mn homeostasis is dynamic in response to illness in mice. This phenomenon is evidenced in male and female mice, mice of two genetic backgrounds (C57/BL6 and BALB/c), in multiple models of acute (dextran-sodium sulfate-induced) and chronic ( enterotoxigenic Bacteriodes fragilis ) colitis, and systemic infection with Candida albicans . When mice were fed a standard corn-based chow with excess Mn (100 ppm), liver Mn decreased and biliary Mn increased 3-fold in response to infection or colitis. Liver iron, copper, and zinc were unchanged. When dietary Mn was restricted to minimally adequate amounts (10ppm), baseline hepatic Mn levels decreased by approximately 60% in the liver, and upon induction of colitis, liver Mn did not decrease further, however biliary Mn still increased 20-fold. In response to acute colitis, hepatic Slc39a8 mRNA (gene encoding the Mn importer, Zip8) and Slc30a10 mRNA (gene encoding the Mn exporter, Znt10) are decreased. Zip8 protein is decreased. Illness- associated dynamic Mn homeostasis may represent a novel host immune/inflammatory response that reorganizes systemic Mn availability through differential expression of key Mn transporters with down-regulation of Zip8.

Cholesterol sulfate limits neutrophil recruitment and gut inflammation during mucosal injury

During mucosal injury, intestinal immune cells play a crucial role in eliminating invading bacteria. However, as the excessive accumulation of immune cells promotes inflammation and delays tissue repair, it is essential to identify the mechanism that limits the infiltration of immune cells to the mucosal-luminal interface. Cholesterol sulfate (CS) is the lipid product of the sulfotransferase SULT2B1 and suppresses immune reactions by inhibiting DOCK2-mediated Rac activation. In this study, we aimed to elucidate the physiological role of CS in the intestinal tract. We found that, in the small intestine and colon, CS is predominantly produced in the epithelial cells close to the lumen. While dextran sodium sulfate (DSS)-induced colitis was exacerbated in Sult2b1-deficient mice with increased prevalence of neutrophils, the elimination of either neutrophils or intestinal bacteria in Sult2b1-deficient mice attenuated disease development. Similar results were obtained when the Dock2 was genetically deleted in Sult2b1-deficient mice. In addition, we also show that indomethacin-induced ulcer formation in the small intestine was exacerbated in Sult2b1-deficient mice and was ameliorated by CS administration. Thus, our results uncover that CS acts on inflammatory neutrophils, and prevents excessive gut inflammation by inhibiting the Rac activator DOCK2. The administration of CS may be a novel therapeutic strategy for inflammatory bowel disease and non-steroidal anti-inflammatory drug-induced ulcers.

A synbiotic combination of Bifidobacterium longum Bif10 and Bifidobacterium breve Bif11, isomaltooligosaccharides and finger millet arabinoxylan prevents dextran sodium sulphate induced ulcerative colitis in mice

Decreased bifidobacterial abundance, disrupted gut barrier function, dysregulated immune response and ulceration have been reported in the gut microbiota of IBD patients. Non-digestible carbohydrates with bifidogenic effect enrich the gut microbiota with Bifidobacterium spp. and could help in overcoming inflammatory gut conditions. In this study, the protective effect of Bifidobacterium longum Bif10 and Bifidobacterium breve Bif11; isomaltooligosaccharides (IMOS); Finger millet arabinoxylan (FM-AX) and their Synbiotic mix were evaluated against dextran sodium sulphate (DSS) induced UC in male Balb/c mice for 25 days. All the interventions ameliorated symptoms of colitis such as disease activity index (DAI), histological damage to the colon, gut-bacterial dysbiosis and inflammation. However, the synbiotic mix was more potent in amelioration of some of the parameters such as decreased TNF-α and lipocalin levels; increased anti-inflammatory markers (IL-10 and IL-22), and improved short chain fatty acids (SCFAs) levels in the cecum content. Furthermore, mouse colitis histological scoring (MCHI) also suggested the preventive role of synbiotic mix. All the dietary interventions aid in improving the DAI and immune parameters; restoration or regeneration of the altered selected gut bacteria, enhances the SCFA production, strengthens gut barrier, prevents gut inflammation and decreases the colonic MCHI score in DSS fed mice.

Ang1 and Ang4 differentially affect colitis and carcinogenesis in an AOM-DSS mouse model

INTRODUCTION

Angiogenin-1 (Ang1) and angiogenin-4 (Ang4) are 14-kDa ribonucleases with potent angiogenic and antimicrobial properties. The role of Ang1 and Ang4 in chronic colitis and colitis-associated cancer has not been previously studied.

METHODS

Wild-type (WT) and angiogenin-1 knock-out (Ang1-KO) C57BL/6 mice were given azoxymethane, a colon carcinogen, 2 days in advance of three cycles of 3.5% dextran sodium sulfate (DSS). Disease activity index (DAI) was recorded, a colonoscopy was performed after each DSS treatment, and mice were euthanized (colitis, recovery, cancer) with tissue evaluated by histopathology. Ang1, Ang4, TNF-α, Il-1F062, IL-6, IL-10, IL-23, IL-33 mRNA levels were analyzed by RT-PCR.

RESULTS

Ang1-KO mice exhibited more severe colitis compared to WT mice during both the acute (P<0.05) and recovery (P<0.05) phases of each DSS cycle. Consistent with these results, colonic TNF-α, IL1-β, IL-6, IL-10, and IL-33 mRNA levels were significantly upregulated in Ang1-KO mice (P<0.05). While Ang4 increased to similar levels in both WT and Ang1-KO mice during colitis and recovery phases, WT mice were distinguished by a significant upregulation of Ang1. Interestingly, despite the reduced colitis, WT mice developed significantly more tumors compared to Ang1-KO mice (P<0.05). 134 tumors formed in WT mice (4.6 tumors/mouse) while only 46 tumors formed (1.5 tumors/mice) in Ang1-KO mice, which were also characterized by a 34-fold decrease in Ang4 compared to WT mice and the complete absence of Ang1.

CONCLUSIONS

In a mouse model of colitis-associated cancer, Ang1-KO mice develop more severe colitis, but fewer tumors compared to WT mice. Ang1 levels correlate with the severity of colitis and the development of colitis-associated cancer, while Ang4 was upregulated during both colitis and cancer. Ang1 and Ang4 play important regulatory roles in the response to chronic colitis and the development of colitis-associated cancer and may serve as novel therapeutic targets.

Adipokine C1q/Tumor Necrosis Factor- Related Protein 3 (CTRP3) Attenuates Intestinal Inflammation Via Sirtuin 1/NF-κB Signaling

BACKGROUND & AIMS

The adipokine CTRP3 has anti-inflammatory effects in several nonintestinal disorders. Although serum CTRP3 is reduced in patients with inflammatory bowel disease (IBD), its function in IBD has not been established. Here, we elucidate the function of CTRP3 in intestinal inflammation.

METHODS

CTRP3 knockout (KO) and overexpressing transgenic (Tg) mice, along with their corresponding wild-type littermates, were treated with dextran sulfate sodium for 6-10 days. Colitis phenotypes and histologic data were analyzed. CTRP3-mediated signaling was examined in murine and human intestinal mucosa and mouse intestinal organoids derived from CTRP3 KO and Tg mice.

RESULTS

CTRP3 KO mice developed more severe colitis, whereas CTRP3 Tg mice developed less severe colitis than wild-type littermates. The deletion of CTRP3 correlated with decreased levels of Sirtuin-1 (SIRT1), a histone deacetylase, and increased levels of phosphorylated/acetylated NF-κB subunit p65 and proinflammatory cytokines tumor necrosis factor-α and interleukin-6. Results from CTRP3 Tg mice were inverse to those from CTRP3 KO mice. The addition of SIRT1 activator resveratrol to KO intestinal organoids and SIRT1 inhibitor Ex-527 to Tg intestinal organoids suggest that SIRT1 is a downstream effector of CTRP3-related inflammatory changes. In patients with IBD, a similar CTRP3/SIRT1/NF-κB relationship was observed.

CONCLUSIONS

CTRP3 expression levels correlate negatively with intestinal inflammation in acute mouse colitis models and patients with IBD. CTRP3 may attenuate intestinal inflammation via SIRT1/NF-κB signaling. The manipulation of CTRP3 signaling, including through the use of SIRT1 activators, may offer translational potential in the treatment of IBD.

Immunoregulatory effects of RGMb in gut inflammation

Graft-versus-host disease (GvHD) is a major complication after allogeneic hematopoietic cell transplantation (HCT). Current strategies to prevent GvHD with immunosuppressive drugs carry significant morbidity and may affect the graft-versus-tumor (GVT) effect. Inflammatory bowel disease (IBD) is an intestinal inflammatory condition that affects more than 2 million people in the United States. Current strategies to prevent colitis with immunosuppressive drugs carry significant morbidity. Recently, Repulsive Guidance Molecule b (RGMb) has been identified as part of a signaling hub with neogenin and BMP receptors in mice and humans. In addition, RGMb binds BMP-2/4 in mice and humans as well as PD-L2 in mice. RGMb is expressed in the gut epithelium and by antigen presenting cells, and we found significantly increased expression in mouse small intestine after total body irradiation HCT conditioning. We hypothesized that RGMb may play a role in GvHD and IBD pathogenesis by contributing to mucosal inflammation. Using major-mismatched HCT mouse models, treatment with an anti-RGMb monoclonal antibody (mAb) that blocks the interaction with BMP-2/4 and neogenin prevented GvHD and improved survival compared to isotype control (75% versus 30% survival at 60 days after transplantation). The GVT effect was retained in tumor models. Using an inflammatory bowel disease dextran sulfate sodium model, treatment with anti-RGMb blocking monoclonal antibody but not isotype control prevented colitis and improved survival compared to control (73% versus 33% at 21 days after treatment) restoring gut homeostasis. Anti-RGMb mAb (9D1) treatment decreased IFN-γ and significantly increased IL-5 and IL-10 in the gut of the treated mice compared to the isotype control treated mice.

Oral Macrocystis pyrifera Fucoidan Administration Exhibits Anti-Inflammatory and Antioxidant Properties and Improves DSS-Induced Colitis in C57BL/6J Mice

Inflammatory bowel disease (IBD) is a complex and multifactorial disorder characterised by relapsing and remitting inflammation of the intestinal tract. Oxidative stress (OS) is the result of an imbalance between production and accumulation of reactive oxygen species (ROS), which has been associated with inflammatory responses and implicated in the exacerbation of IBD. Fucoidan, a sulfated polysaccharide from brown seaweed, is a well-known anti-inflammatory agent and emerging evidence indicates that fucoidan extracts from Macrocystis pyrifera (MPF and DP-MPF) may also modulate oxidative stress. This study investigated the impact of fucoidan extracts, MPF and DP-MPF in a dextran sodium sulphate (DSS)-induced mouse model of acute colitis. 3% DSS was administered in C57BL/6J male mice over a period of 7 days, and MPF and DP-MPF were co-administered orally at a dose of 400 mg/kg body weight. Our results indicated that MPF and DP-MPF significantly prevented body weight loss, improved the disease activity index (DAI), restored colon lengths, reduced the wet colon weight, reduced spleen enlargement, and improved the overall histopathological score. Consistent with the reported anti-inflammatory functions, fucoidan extracts, MPF and DP-MPF significantly reduced the colonic levels of myeloperoxidase (MPO), nitric oxide (NO), malondialdehyde (MDA) and increased the levels of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT). In addition, MPF and DP-MPF significantly inhibited levels of pro-inflammatory cytokines in colon-derived tissues. Collectively, our results indicate that MPF and DP-MPF exhibited anti-inflammatory and antioxidant effects representing a promising therapeutic strategy for the cure of IBD.

Increased stromal PFKFB3-mediated glycolysis in inflammatory bowel disease contributes to intestinal inflammation

Inflammatory bowel disease (IBD) is a chronic relapsing inflammation of the intestinal tract with currently not well-understood pathogenesis. In addition to the involvement of immune cells, increasing studies show an important role for fibroblasts in the pathogenesis of IBD. Previous work showed that glycolysis is the preferred energy source for fibroblasts in fibrotic diseases. 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase 3 (PFKFB3) is a key kinase supporting glycolysis. Increased expression of PFKFB3 in several cancers and inflammatory diseases has been previously reported, but the metabolic status of fibroblasts and the role of PFKFB3 in patients with IBD are currently unknown. Therefore, in this study, we evaluated the role of glycolysis and PFKFB3 expression in IBD. Single-sample gene set enrichment analysis (ssGSEA) revealed that glycolysis was significantly higher in IBD intestinal samples, compared to healthy controls, which was confirmed in the validation cohorts of IBD patients. Single-cell sequencing data indicated that PFKFB3 expression was higher in IBD-derived stromal cells. In vitro, PFKFB3 expression in IBD-derived fibroblasts was increased after the stimulation with pro-inflammatory cytokines. Using seahorse real-time cell metabolic analysis, inflamed fibroblasts were shown to have a higher extracellular acidification rate and a lower oxygen consumption rate, which could be reversed by inhibition of JAK/STAT pathway. Furthermore, increased expression of pro-inflammatory cytokines and chemokines in fibroblasts could be reverted by PFK15, a specific inhibitor of PFKFB3. In vivo experiments showed that PFK15 reduced the severity of dextran sulfate sodium (DSS)- and Tcell transfer induced colitis, which was accompanied by a reduction in immune cell infiltration in the intestines. These findings suggest that increased stromal PFKFB3 expression contributes to inflammation and the pathological function of fibroblasts in IBD. Inhibition of PFKFB3 suppressed their inflammatory characteristics.

CD4+-mediated colitis in mice is independent of the GPR183 and GPR18 pathways

Colitis is characterized by an exacerbated intestinal immune response, but the genetic and other mechanisms regulating immune activation remain incompletely understood. In order to identify new pathways leading to colitis, we sought to identify genes with increased expression in the colons of patients that also are near loci identified by genome wide association studies (GWAS) associated with IBD risk. One such SNP, rs9557195 was of particular interest because it is within an intron of G-protein-coupled receptor (GPR) 183, known to be important for lymphocyte migration. Furthermore, this SNP is in close proximity to the gene encoding another G-protein coupled receptor, GPR18. Analyzing publicly available datasets, we found transcripts of GPR183 and GPR18 to be increased in colon biopsies from ulcerative colitis and Crohn's disease patients, and GPR183 was even more increased in patients resistant to TNF treatment. Expression of both genes also was increased in mouse models of colitis. Therefore, our aim was to understand if increased expression of these GPRs in the intestine is related to disease severity in colitis models. Here we investigated the role of these receptors in the T cell transfer model and the dextran sulfate sodium model. In the T cell transfer model, GPR183 expression on donor T cells, as well as on other cell types in the Rag-/- recipients, was not essential for severe colitis induction. Furthermore, deficiency in Rag-/- mice for the enzyme that synthesizes a cholesterol metabolite that is a major ligand for GPR183 also did not affect disease. Similarly, lack of GPR18 expression in T cells or other cell types did not affect colitis pathogenesis in the T cell transfer or in the dextran sulfate sodium model. Therefore, despite increased expression of transcripts for these genes in the intestine during inflammation in humans and mice, they are not required for disease severity in mouse models of colitis induced by chemical injury or T cell cytokines, perhaps due to redundancy in mechanisms important for homing and survival of lymphocytes to the inflamed intestine.

Nociceptor neurons direct goblet cells via a CGRP-RAMP1 axis to drive mucus production and gut barrier protection

Neuroepithelial crosstalk is critical for gut physiology. However, the mechanisms by which sensory neurons communicate with epithelial cells to mediate gut barrier protection at homeostasis and during inflammation are not well understood. Here, we find that Nav1.8+CGRP+ nociceptor neurons are juxtaposed with and signal to intestinal goblet cells to drive mucus secretion and gut protection. Nociceptor ablation led to decreased mucus thickness and dysbiosis, while chemogenetic nociceptor activation or capsaicin treatment induced mucus growth. Mouse and human goblet cells expressed Ramp1, receptor for the neuropeptide CGRP. Nociceptors signal via the CGRP-Ramp1 pathway to induce rapid goblet cell emptying and mucus secretion. Notably, commensal microbes activated nociceptors to control homeostatic CGRP release. In the absence of nociceptors or epithelial Ramp1, mice showed increased epithelial stress and susceptibility to colitis. Conversely, CGRP administration protected nociceptor-ablated mice against colitis. Our findings demonstrate a neuron-goblet cell axis that orchestrates gut mucosal barrier protection.

Gender-based effect of absence of gut microbiota on the protective efficacy of Bifidobacterium longum-fermented rice bran diet against inflammation-associated colon tumorigenesis

Dietary rice bran (RB) has shown capacity to influence metabolism by modulation of gut microbiota in individuals at risk for colorectal cancer (CRC), which warranted attention for delineating mechanisms for bidirectional influences and cross-feeding between the host and RB-modified gut microbiota to reduce CRC. Accordingly, in the present study, fermented rice bran (FRB, fermented with a RB responsive microbe Bifidobacterium longum), and non-fermented RB were fed as 10% w/w (diet) to gut microbiota-intactspf or germ-free micegf to investigate comparative efficacy against inflammation-associated azoxymethane/dextran sodium sulfate (AOM/DSS)-induced CRC. Results indicated both microbiota-dependent and independent mechanisms for RB meditated protective efficacy against CRC that was associated with reduced neoplastic lesion size and local-mucosal/systemic inflammation, and restoration of colonic epithelial integrity. Enrichment of beneficial commensals (such as, Clostridiales, Blautia, Roseburia), phenolic metabolites (benzoate and catechol metabolism), and dietary components (ferulic acid-4 sulfate, trigonelline, and salicylate) were correlated with anti-CRC efficacy. Germ-free studies revealed gender-specific physiological variables could differentially impact CRC growth and progression. In the germ-free females, the RB dietary treatment showed a ∼72% reduction in the incidence of colonic epithelial erosion when compared to the ∼40% reduction in FRB-fed micegf . Ex vivo fermentation of RB did not parallel the localized-protective benefits of gut microbial metabolism by RB in damaged colonic tissues. Findings from this study suggest potential needs for safety considerations of fermented fiber rich foods as dietary strategies against severe inflammation-associated colon tumorigenesis (particularly with severe damage to the colonic epithelium).

Soluble Protein Hydrolysate Ameliorates Gastrointestinal Inflammation and Injury in 2,4,6-Trinitrobenzene Sulfonic Acid-Induced Colitis in Mice

Inflammatory bowel diseases (IBD) are chronic, recurring gastrointestinal diseases that severely impair health and quality of life. Although therapeutic options have significantly expanded in recent years, there is no effective therapy for a complete and permanent cure for IBD. Well tolerated dietary interventions to improve gastrointestinal health in IBD would be a welcome advance especially with anticipated favorable tolerability and affordability. Soluble protein hydrolysate (SPH) is produced by the enzymatic hydrolysis of commercial food industry salmon offcuts (consisting of the head, backbone and skin) and contains a multitude of bioactive peptides including those with anti-oxidant properties. This study aimed to investigate whether SPH ameliorates gastrointestinal injury in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced mouse colitis model. Mice were randomly assigned to four groups: Control (no colitis), Colitis, Colitis/CP (with control peptide treatment), and Colitis/SPH (with SPH treatment). Colitis was induced by cutaneous sensitization with 1% TNBS on day −8 followed by 2.5% TNBS enema challenge on day 0. Control peptides and SPH were provided to the mice in the Colitis/CP or Colitis/SPH group respectively by drinking water at the final concentration of 2% w/v daily from day −10 to day 4. Then, the colon was harvested on day 4 and examined macro- and microscopically. Relevant measures included disease activity index (DAI), colon histology injury, immune cells infiltration, pro- and anti-inflammatory cytokines and anti-oxidative gene expression. It was found that SPH treatment decreased the DAI score and colon tissue injury when compared to the colitis-only and CP groups. The protective mechanisms of SPH were associated with reduced infiltration of CD4⁺ T, CD8⁺ T and B220⁺ B lymphocytes but not macrophages, downregulated pro-inflammatory cytokines (tumor necrosis factor-α and interleukin-6), and upregulated anti-inflammatory cytokines (transforming growth factor-β1 and interleukin-10) in the colon tissue. Moreover, the upregulation of anti-oxidative genes, including ferritin heavy chain 1, heme oxygenase 1, NAD(P)H quinone oxidoreductase 1, and superoxide dismutase 1, in the colons of colitis/SPH group was observed compared with the control peptide treatment group. In conclusion, the protective mechanism of SPH is associated with anti-inflammatory and anti-oxidative effects as demonstrated herein in an established mice model of colitis. Clinical studies with SPH as a potential functional food for the prevention or as an adjuvant therapy in IBD may add an effective and targeted diet-based approach to IBD management in the future.

Ameliorative Effect of Citropten Isolated from Citrusaurantifolia Peel Extract as a Modulator of T Cell and Intestinal Epithelial Cell Activity in DSS-Induced Colitis

Citropten is a coumarin that is mainly found in fruits of Rutaceae trees, but its anti-inflammatory activities in colitis is still unknown. In this study, we investigated its attenuating effect of citropten isolated from Citrus aurantifolia extract on DSS-induced colitis through the modulation of the activity of T cells and intestinal epithelial cells. We found that pre-treatment with citropten downregulates the activity of T cells and intestinal epithelial cells without a negative effect on the viability of Jurkat and HT-29 cells. The results from the Western blot analysis revealed that pre-treatment with citropten reduces the NFκB and MAPK signaling pathway in activated T cells and intestinal epithelial cells. We elucidated that the oral administration of citropten alleviates the colonic inflammation and activity of effector T cells in DSS-induced colitis by measuring changes in body weight, histological scoring from H&E-stained sections, mRNA levels of pro-inflammatory cytokines and the phosphorylation level of the MAPK signaling pathway.

Redefining the Foreign Antigen and Self-Driven Memory CD4+ T-Cell Compartments via Transcriptomic, Phenotypic, and Functional Analyses

Under steady-state conditions, conventional CD4⁺ T lymphocytes are classically divided into naïve (CD44^lo CD62L^hi) and memory (CD44^hi CD62L^lo) cell compartments. While the latter population is presumed to comprise a mixture of distinct subpopulations of explicit foreign antigen (Ag)-specific “authentic” memory and foreign Ag-independent memory-phenotype (MP) cells, phenotypic markers differentially expressed in these two cell types have yet to be identified. Moreover, while MP cells themselves have been previously described as heterogeneous, it is unknown whether they consist of distinct subsets defined by marker expression. In this study, we demonstrate using combined single-cell RNA sequencing and flow cytometric approaches that self-driven MP CD4⁺ T lymphocytes are divided into CD127^hi Sca1^lo, CD127^hi Sca1^hi, CD127^lo Sca1^hi, and CD127^lo Sca1^lo subpopulations that are Bcl2^lo, while foreign Ag-specific memory cells are CD127^hi Sca1^hi Bcl2^hi. We further show that among the four MP subsets, CD127^hi Sca1^hi lymphocytes represent the most mature and cell division-experienced subpopulation derived from peripheral naïve precursors. Finally, we provide evidence arguing that this MP subpopulation exerts the highest responsiveness to Th1-differentiating cytokines and can induce colitis. Together, our findings define MP CD4⁺ T lymphocytes as a unique, self-driven population consisting of distinct subsets that differ from conventional foreign Ag-specific memory cells in marker expression and establish functional relevance for the mature subset of CD127^hi Sca1^hi MP cells.

Label-Free Characterization and Quantification of Mucosal Inflammation in Common Murine Colitis Models With Multiphoton Imaging

BACKGROUND

Clinical challenges in inflammatory bowel diseases require microscopic in vivo evaluation of inflammation. Here, label-free imaging holds great potential, and recently, our group demonstrated the advantage of using in vivo multiphoton endomicroscopy for longitudinal animal studies. This article extends our previous work by in-depth analysis of label-free tissue features in common colitis models quantified by the multiphoton colitis score (MCS).

METHODS

Fresh mucosal tissues were evaluated from acute and chronic dextran sulfate sodium (DSS), TNBS, oxazolone, and transfer colitis. Label-free imaging was performed by using second harmonic generation and natural autofluorescence. Morphological changes in mucosal crypts, collagen fibers, and cellularity in the stroma were analyzed and graded.

RESULTS

Our approach discriminated between healthy (mean MCS = 2.5) and inflamed tissue (mean MCS > 5) in all models, and the MCS was validated by hematoxylin and eosin scoring of the same samples (85.2% agreement). Moreover, specific characteristics of each phenotype were identified. While TNBS, oxazolone, and transfer colitis showed high cellularity in stroma, epithelial damage seemed specific for chronic, acute DSS and transfer colitis. Crypt deformations were mostly observed in acute DSS.

CONCLUSIONS

Quantification of label-free imaging is promising for in vivo endoscopy. In the future, this could be valuable for monitoring of inflammatory pathways in murine models, which is highly relevant for the development of new inflammatory bowel disease therapeutics.

Metformin Protects the Intestinal Barrier by Activating Goblet Cell Maturation and Epithelial Proliferation in Radiation-Induced Enteropathy

Radiotherapy or accidental exposure to high-dose radiation can cause severe damage to healthy organs. The gastrointestinal (GI) tract is a radiation-sensitive organ of the body. The intestinal barrier is the first line of defense in the GI tract, and consists of mucus secreted by goblet cells and a monolayer of epithelium. Intestinal stem cells (ISCs) help in barrier maintenance and intestinal function after injury by regulating efficient regeneration of the epithelium. The Wnt/β-catenin pathway plays a critical role in maintaining the intestinal epithelium and regulates ISC self-renewal. Metformin is the most widely used antidiabetic drug in clinical practice, and its anti-inflammatory, antioxidative, and antiapoptotic effects have also been widely studied. In this study, we investigated whether metformin alleviated radiation-induced enteropathy by focusing on its role in protecting the epithelial barrier. We found that metformin alleviated radiation-induced enteropathy, with increased villi length and crypt numbers, and restored the intestinal barrier function in the irradiated intestine. In a radiation-induced enteropathy mouse model, metformin treatment increased tight-junction expression in the epithelium and inhibited bacterial translocation to mesenteric lymph nodes. Metformin increased the number of ISCs from radiation toxicity and enhanced epithelial repair by activating Wnt/β-catenin signaling. These data suggested that metformin may be a potential therapeutic agent for radiation-induced enteropathy.

Zbtb20 identifies and controls a thymus-derived population of regulatory T cells that play a role in intestinal homeostasis

The expression of BTB-ZF transcription factors such as ThPOK in CD4⁺ T cells, Bcl6 in T follicular helper cells, and PLZF in natural killer T cells defines the fundamental nature and characteristics of these cells. Screening for lineage-defining BTB-ZF genes led to the discovery of a subset of T cells that expressed Zbtb20. About half of Zbtb20⁺ T cells expressed FoxP3, the lineage-defining transcription factor for regulatory T cells (T_regs). Zbtb20⁺ T_regs were phenotypically and genetically distinct from the larger conventional T_reg population. Zbtb20⁺ T_regs constitutively expressed mRNA for interleukin-10 and produced high levels of the cytokine upon primary activation. Zbtb20⁺ T_regs were enriched in the intestine and specifically expanded when inflammation was induced by the use of dextran sodium sulfate. Conditional deletion of Zbtb20 in T cells resulted in a loss of intestinal epithelial barrier integrity. Consequently, knockout (KO) mice were acutely sensitive to colitis and often died because of the disease. Adoptive transfer of Zbtb20⁺ T_regs protected the Zbtb20 conditional KO mice from severe colitis and death, whereas non-Zbtb20 T_regs did not. Zbtb20 was detected in CD24^hi double-positive and CD62L^lo CD4 single-positive thymocytes, suggesting that expression of the transcription factor and the phenotype of these cells were induced during thymic development. However, Zbtb20 expression was not induced in "conventional" T_regs by activation in vitro or in vivo. Thus, Zbtb20 expression identified and controlled the function of a distinct subset of T_regs that are involved in intestinal homeostasis.