Therapeutic Target In Inflammatory Bowel Disease Research Articles

DOP076 Translational and preclinical study validating anterior gradient 2 as a novel epithelial therapeutic target in Inflammatory Bowel Disease (IBD) involved in inflammation, fibrosis, and intestinal barrier integrity

Abstract Background Anterior Gradient 2 (AGR2) is an endoplasmic reticulum (ER) resident protein involved in protein folding, predominantly expressed in mucin-secreting epithelial cells. Under stress, AGR2 is secreted into the extracellular milieu (eAGR2), where it disrupts epithelial integrity, attracts monocytes, and activates fibroblasts. We explored the relationship between AGR2 tissue expression in IBD patients and the efficacy of a neutralizing anti-eAGR2 antibody (TH-009) in murine models of colonic inflammation and fibrosis Methods AGR2 expression was analyzed by immunohistochemistry on ileal and colonic biopsies from IBD patients and controls. In mice, the efficacy of TH-009 was evaluated in models of colitis (3% DSS) and digestive fibrosis (3 cycles of 1.5% DSS) Results 132 ileal and colonic endoscopic biopsies from 66 patients with Crohn’s disease (CD), 50 patients with ulcerative colitis (UC), and 16 controls, and 96 surgical samples from 11 CD patients, 24 UC patients, and 11 controls were included. AGR2 expression correlated with mucosal inflammation (R² = 0.416, p<0.0001) and tissue damage (R² = 0.329, p<0.0001). All patients with mucosal inflammation showed AGR2 overexpression, while 38% of histologically healed patients had high AGR2, with a relapse rate at 18 months three times higher than those whose AGR2 levels were comparable to controls.In a murine acute colitis model (3% DSS), intravenous (IV) treatment with TH-009 at doses of 5 and 20 µg showed an improvement in weight (p<0.005 and p=0.0001, respectively), in the global colitis DAI score (p=0.002 and p=0.001), and in the histological colitis score (p=0.04 for 5 µg) compared to controls. Intraperitoneal and subcutaneous administration were also effective. There was a significant reduction in tissue infiltration by macrophages (p<0.01) and T lymphocytes (p<0.001), in myeloperoxidase activity, and in the tissue and serum expression of pro-inflammatory cytokines TNFα and IL-6. TH-009-treated mice restored intestinal permeability, measured by FITC-Dextran blood passage, to levels comparable to unexposed DSS mice, unlike DSS-only exposed mice (p<0.01). In a fibrosis model (3 cycles of 1.5% DSS), preventive and curative treatment with TH-009 reduced digestive fibrosis by 49% (p<0.0001), and reduced submucosal fibrosis thickness by 59% (p<0.0001). There was a significant decrease in the colonic expression of fibrosis-related genes (Collagen A1, αSMA, fibrinogen, and TGFβ). Conclusion AGR2 is a novel therapeutic target in IBD, correlating with inflammation and complications. Its expression is not affected by major therapies and is overexpressed in 40% of patients with deep histological healing. TH-009 improves inflammation, reverses fibrosis, and restores epithelial barrier functions.

P0006 Developmentally endothelial locus-1 promotes intestinal inflammation resolution through inhibition of the Cmpk2-cGAS-STING pathway and regulates reparatory macrophage transition

Abstract Background Abnormalities in inflammation resolution function are closely associated with chronic inflammation, and proresolution therapies may provide new opportunities for the treatment of inflammatory bowel disease (IBD). Developmental endothelial locus 1 (DEL-1) is an important endogenous molecule that regulates tissue immune homeostasis and promotes resolution of inflammation, but its effect on IBD remains unknown. Here, we aimed to explore the expression and roles of DEL-1 in IBD. Methods DEL-1 levels were examined in patients with IBD, mice with colitis, and LPS-induced RAW264.7 cells. DEL-1 overexpression plasmids and/or DEL-1-Fc intervened in cells and mice to explore it effects in the acute and recovery phases of inflammation. Moreover, flow cytometry, RNA-Seq, chromatin immunoprecipitation (ChIP), dual-luciferase reporter assays and 16S rRNA were used to illustrate the potential mechanism of DEL-1 in colitis. Results DEL-1 levels were remarkably lower in IBD patients, colitis mice, and LPS-induced RAW264.7 cells, while the levels increased with inflammation to resolve. Transfection with DEL-1 overexpression plasmid and/or DEL-1-Fc intervention reduces levels of inflammatory cytokines in both phases and upregulates reparative gene levels in the recovery phase. Mechanistically, we demonstrated that DEL-1 inhibits Cytosine monophosphate kinase 2 (Cmpk2)-dependent mtDNA synthesis, thereby inhibiting the cGAS-STING pathway to ameliorate intestinal inflammation. Moreover, DEL-1 promoted reparative macrophage transition in the repair model of colitis. Spi1 was identified as a transcription factor that regulates Cmpk2 and the reparative gene Il10. Intervention with overexpression plasmid of Spi1 or Cmpk2 or the STING agonist DMXAA reverses the effects of DEL-1. DEL-1 also inhibits neutrophil recruitment, repairs the intestinal barrier, and improves intestinal microbiota dysbiosis. Conclusion This is the first study to show that DEL-1 effectively attenuates colonic inflammation in mice with DSS-induced colitis by inhibits the Cmpk2-cGAS-STING pathway and regulates reparatory macrophage transition, thus providing a novel therapeutic target for IBD.

P0255 Predictive potential of microRNA expression for Juvenile Idiopathic Arthritis development in paediatric Inflammatory Bowel Disease

Abstract Background Children diagnosed with inflammatory bowel disease (IBD) often experience a more severe disease course than adults, and up to 50% develop extra-intestinal manifestations (EIMs).1 The most common EIM is juvenile idiopathic arthritis (JIA), affecting approximately 16–33% of paediatric patients with IBD, increasing risks of long-term complications such as uveitis, joint destruction, reduced physical activity, and psychological challenges.2 MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate gene expression and play key roles in immune and inflammatory processes. They hold potential as biomarkers and therapeutic targets in IBD, offering opportunities for advancements in early diagnosis and treatment.3 The aim of this study was to investigate whether miRNA expressed in intestinal biopsies can identify paediatric patients with IBD at risk of developing JIA. Methods Paediatric patients under 18 years of age diagnosed with IBD between 1 May 2021 and 1 May 2024, along with healthy controls from the Copenhagen IBD Inception Cohort, were enrolled.4 One mucosal biopsy from either the ileum or colon was collected from each patient during their index endoscopy. Additionally, biopsies from paediatric patients diagnosed with both IBD and JIA (IBD-JIA) prior to 1 May 2021 were retreived from the Department of Pathology at Copenhagen University Hospital, Hvidovre. Total RNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissue, and miRNA expression was analysed using the GeneChip™ microarray platform. Results The study included 62 biopsies from 62 patients (27 with IBD, 25 with both IBD and JIA (IBD-JIA), and 10 HC). Patient characteristics are shown in table 1. Analysis identified 532 significantly differentially expressed probe sets (adjusted p<0.05) among IBD, IBD-JIA, and HC (Figure 1). Among these, 123 probe sets, including miR-486-2, let-7b-5p, and miR-92a-3p, exhibited a more than two-fold change (adjusted p<0.001) between IBD and IBD-JIA, with 120 miRNAs upregulated and 3 downregulated in IBD-JIA compared to IBD. Conclusion This study provides the first evidence of differential miRNA expression in paediatric patients with IBD and co-occurring JIA. These miRNAs may serve as novel biomarkers for the early detection, aiding in timely diagnosis and better management of paediatric IBD patients.

Vagal stimulation ameliorates murine colitis by regulating SUMOylation.

Inflammatory bowel diseases (IBDs) are chronic debilitating conditions without cure, the etiologies of which are unknown, that shorten the lifespans of 7 million patients worldwide by nearly 10%. Here, we found that decreased autonomic parasympathetic tone resulted in increased IBD susceptibility and mortality in mouse models of disease. Conversely, vagal stimulation restored neuromodulation and ameliorated colitis by inhibiting the posttranslational modification SUMOylation through a mechanism independent of the canonical interleukin-10/α7 nicotinic cholinergic vagal pathway. Colonic biopsies from patients with IBDs and mouse models showed an increase in small ubiquitin-like modifier (SUMO)2 and SUMO3 during active disease. In global genetic knockout mouse models, the deletion of Sumo3 protected against development of colitis and delayed onset of disease, whereas deletion of Sumo1 halted the progression of colitis. Bone marrow transplants from Sumo1-knockout (KO) but not Sumo3-KO mice into wild-type mice conferred protection against development of colitis. Electric stimulation of the cervical vagus nerve before the induction of colitis inhibited SUMOylation and delayed the onset of colitis in Sumo1-KO mice and resulted in milder symptoms in Sumo3-KO mice. Treatment with TAK-981, a first-in-class inhibitor of the SUMO-activating enzyme, ameliorated disease in three murine models of IBD and reduced intestinal permeability and bacterial translocation in a severe model of the disease, suggesting the potential to reduce progression to sepsis. These results reveal a pathway of vagal neuromodulation that reprograms endogenous stress-adaptive responses through inhibition of SUMOylation and suggest SUMOylation as a therapeutic target for IBD.

Stromal-Like Cells Are Found in Peripheral Blood of Patients With Inflammatory Bowel Disease and Correlate With Immune Activation State.

Recent studies have identified a critical role of stromal-immune cell interactions in immunity and immune tolerance. Transcriptomic profiling has implicated stromal cells in immune-mediated disorders including the 2 common forms of inflammatory bowel disease (IBD), Crohn's disease (CD), and ulcerative colitis (UC). Stromal-immune interactions may edify inflammatory state and the development of IBD-related complications such as fibrosis, yet the lack of protein markers has hampered studying stromal-immune perturbation. In this study, we designed a 40-color spectral flow cytometry assay to characterize hematopoietic and nonhematopoietic cells in intestinal biopsies and matched blood samples from patients with CD or UC. We identified circulating stromal-like cells that are significantly more abundant in IBD blood samples than in healthy controls. Those cells expressed podoplanin (PDPN), a commonly used marker for fibroblasts, and they were associated with activated and memory T and B cells and altered natural killer cell, monocyte, and macrophage populations. PDPN + cells in the blood correlated with PDPN + cells in the colon. Principal component analysis distinctly separated healthy blood samples from IBD blood samples, with stromal-like cells and B-cell subtypes dominating the IBD signature; Pearson correlation detected an association between PDPN + stromal-like cells and B-cell populations in IBD blood and gut biopsies. These observations suggest that PDPN + cells in the blood may serve as a biomarker of IBD. Understanding the relationship between stromal cells and immune cells in the intestine and the blood may provide a window into disease pathogenesis and insight into therapeutic targets for IBD.

Anti-Inflammatory Effects of miR-369-3p via PDE4B in Intestinal Inflammatory Response.

Cyclic nucleotide phosphodiesterases (PDEs) consist of a family of enzymes expressed in several types of cells, including inflammatory cells, that play a pivotal role in inflammation. Several studies have demonstrated that the inhibition of PDE4 results in a reduced inflammatory response via PKA and CREB signaling. Hence, PDE4 suppression improves the inflammatory feedback typical of several diseases, such as inflammatory bowel disease (IBD). In our previous studies, we have demonstrated that miR-369-3p regulates inflammatory responses, modulating different aspects of the inflammatory process. The aim of this study was to demonstrate an additional anti-inflammatory effect of miR-369-3p targeting PDE4B, one of the widely expressed isoforms in immune cells. We found that miR-369-3p was able to reduce the expression of PDE4B, elevating the intracellular levels of cAMP. This accumulation increased the expression of PKA and pCREB, mitigating the release of pro-inflammatory cytokines and promoting the release of anti-inflammatory cytokines. To prove that PDE4B is a good therapeutic target in IBD, we also demonstrate that the expression of PDE4B was increased in UC patients compared to healthy controls, affecting the immune infiltrate. PDE4B is considered an important player in inflammatory progression; hence, our results show the ability of miR-369-3p to ameliorate inflammation by targeting PDE4B, supporting its future application as a new therapeutic approach in IBD.

Fibroblast growth factor receptor 4 deficiency in macrophages aggravates experimental colitis by promoting M1-polarization.

Compelling evidence indicates that dysregulated macrophages may play a key role in driving inflammation in inflammatory bowel disease (IBD). Fibroblast growth factor (FGF)-19, which is secreted by ileal enterocytes in response to bile acids, has been found to be significantly lower in IBD patients compared to healthy individuals, and is negatively correlated with the severity of diarrhea. This study aims to explore the potential impact of FGF19 signaling on macrophage polarization and its involvement in the pathogenesis of IBD. The dextran sulfate sodium (DSS)-induced mouse colitis model was utilized to replicate the pathology of human IBD. Mice were created with a conditional knockout of FGFR4 (a specific receptor of FGF19) in myeloid cells, as well as mice that overexpressing FGF19 specifically in the liver. The severity of colitis was measured using the disease activity index (DAI) and histopathological staining. Various techniques such as Western Blotting, quantitative PCR, flow cytometry, and ELISA were employed to assess polarization and the expression of inflammatory genes. Myeloid-specific FGFR4 deficiency exacerbated colitis in the DSS mouse model. Deletion or inhibition of FGFR4 in bone marrow-derived macrophages (BMDMs) skewed macrophages towards M1 polarization. Analysis of transcriptome sequencing data revealed that FGFR4 deletion in macrophages significantly increased the activity of the complement pathway, leading to an enhanced inflammatory response triggered by LPS. Mechanistically, FGFR4-knockout in macrophages promoted complement activation and inflammatory response by upregulating the nuclear factor-κB (NF-κB)-pentraxin3 (PTX3) pathway. Additionally, FGF19 suppressed these pathways and reduced inflammatory response by activating FGFR4 in inflammatory macrophages. Liver-specific overexpression of FGF19 also mitigated inflammatory responses induced by DSS in vivo. Our study highlights the significance of FGF19-FGFR4 signaling in macrophage polarization and the pathogenesis of IBD, offering a potential new therapeutic target for IBD.

Ribonuclease 4 functions as an intestinal antimicrobial protein to maintain gut microbiota and metabolite homeostasis

Antimicrobial proteins contribute to host-microbiota interactions and are associated with inflammatory bowel disease (IBD), but our understanding on antimicrobial protein diversity and functions remains incomplete. Ribonuclease 4 (Rnase4) is a potential antimicrobial protein with no known function in the intestines. Here we find that RNASE4 is expressed in intestinal epithelial cells (IEC) including Paneth and goblet cells, and is detectable in human and mouse stool. Results from Rnase4-deficient mice and recombinant protein suggest that Rnase4 kills Parasutterella to modulate intestinal microbiome, thereby enhancing indoleamine-2,3-dioxygenase 1 (IDO1) expression and subsequently kynurenic and xanthurenic acid production in IECs to reduce colitis susceptibility. Furthermore, deceased RNASE4 levels are observed in the intestinal tissues and stool from patients with IBD, correlating with increased stool Parasutterella. Our results thus implicate Rnase4 as an intestinal antimicrobial protein regulating gut microbiota and metabolite homeostasis, and as a potential diagnostic biomarker and therapeutic target for IBD.

Atox1 regulates macrophage polarization in intestinal inflammation via ROS-NLRP3 inflammasome pathway

BackgroundInflammation and oxidative stress play an important role in the pathophysiology of inflammatory bowel disease (IBD). This study aimed to explore the effects of copper chaperone Antioxidant-1 (Atox1) on macrophages in a mouse model of intestinal inflammation.MethodsA mouse model of TNBS-induced colitis was established and verified using the disease activity index. Atox1 conditional knockout mice were applied. The proportion of macrophages in colonic lamina propria mononuclear cells and ROS production were analyzed using flow cytometry. Inflammatory cytokines were measured using ELISA. Expression of macrophage M1/M2 polarization markers, p47phox, NLRP3, and Caspase-1 p20 was measured using quantitative RT-PCR and Western blotting.ResultsAtox1 expression was up-regulated in colon tissues of TNBS-induced colitis mice. Macrophages isolated from TNBS-induced colitis mice showed M1 polarization and nuclear translocation of Atox1. Inhibiting copper chaperone activity decreased p47phox, ROS production, and M1 polarization induced by CuCl2 in macrophages. TNBS induced up-regulation of inflammatory cytokines, M1 polarization markers, and p47phox expression in mice, an effect which was preempted by Atox1 knockout. Inflammatory cytokines and expression of M1 polarization markers, p47phox, NLRP3, Caspase-1 p20 were also increased in macrophages isolated from TNBS-induced colitis mice. These changes were alleviated in mice with Atox1 knockout. The effects of Atox1 on macrophage polarization were mediated via the ROS-NLRP3 inflammasome pathway.ConclusionAtox1 plays a pro-inflammatory role, promotes M1 polarization of macrophages, and increases the concentrations of pro-inflammatory cytokines in intestinal tissue by regulating the ROS-NLRP3 inflammasome pathway. Atox1 is a potential therapeutic target in IBD.

Serum fibroblast growth factor 19 level correlates inversely with clinical and endoscopic activity of inflammatory bowel disease.

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), is a chronic condition with relapsing-remitting course. Diarrhea and abdominal pain are the most common IBD symptoms. Fibroblast growth factor 19 (FGF19) is an endocrine factor that inhibits hepatic bile acid production and may be used as a diagnostic marker for bile acid malabsorption. To assess serum FGF19 levels in active and inactive phases of IBD and find a potential correlation between FGF19 and disease activity. Fasting serum FGF19 levels were measured in 105 IBD patients (47 UC patients, 41 CD patients without previous ileocecal resection (NR-CD), 17 CD patients after ileocecal resection (IR-CD), and 17 control subjects). The disease activity was assessed using clinical, laboratory and endoscopic criteria. Inverse correlations were found between FGF19 level and intensity of diarrhea (in UC), abdominal pain intensity (in UC and IR-CD) and inflammatory markers (in UC and IR-CD). Moreover, FGF19 concentration was inversely correlated with clinical and endoscopic activity indices in UC and CD. Fluctuations in FGF19 level related to clinical and endoscopic activity of UC and CD revealed a clear pattern of higher values in remission than in active disease phases. Fibroblast growth factor 19 may serve as a potential diagnostic biomarker and constitute a new therapeutic target in IBD.

P082 Downregulated apelin expression in T cells in the setting of Chronic Colitis

Abstract Background APJ is a G protein-coupled receptor and was originally found as an orphan receptor. Isolation of apelin (APL) from the alimentary tract was found to be the endogenous ligand for APJ. It has been reported that APL is upregulated in the colonic tissues of a murine model of acute colitis induced by dextran sodium sulfate (DSS), and thus it may be suggested to be associated with the pathogenesis of inflammatory bowel diseases (IBD) in humans. However, the mechanism and function of APL in the context of IBD are still not understood. Here, we analyzed APL expression in an animal model of chronic colitis to define its function in the pathogenesis of IBD. Methods Each cell type in the colonic tissue, including epithelial cells and lamina propria lymphocytes, were first isolated from wild type C57BL6 mice (WT) to assess APL expression. Next, naïve T cells isolated from WT were adoptively transferred into Rag deficient mice (Rag-/-) to induce chronic colitis, and then APL expression was measured either in the colonic tissue or in the isolated splenic and colonic CD4+ T cells from these T cell-reconstituted Rag-/- to compare with those of WT or Rag-/- without colitis. In addition, WT naïve T cells were differentiated into either Th1, Th2 or Th17 in vitro to analyze APL expression. Finally, the Rag-/- receiving naïve T cells were administered a synthetic APL peptide, APL-13, to assess the severity of colitis. Results Semi-quantitative PCR (qPCR) revealed that CD4+ T cells express relatively higher level of APL compared to other cell types including the epithelial cells in colonic tissue from WT. However, APL expression in the colonic tissues from the Rag-/- induced chronic colitis was unexpectedly downregulated compared to control groups without colitis; this is not consistent with the previous report using acute DSS colitis model. Subsequently, qPCR revealed significantly decreased APL expression in the splenic and colonic T cells from Rag-/- induced colitis compared to that of WT. APL expressions in the effecter T cells in vivo and all of the differentiated T cells in vitro were also significantly downregulated compared to naïve T cells and non-differentiated control T cells, respectively. Given these results, APL-13 was injected into the Rag-/- that underwent T cell reconstitution to antagonize the APL downregulation. This resulted in reduced severity of colitis compared to that of vehicle control-injected group. Conclusion These results suggest that T cells can be one of the major sources of APL in colonic tissues, and APL downregulation in effecter T cells may lead to the development of chronic colitis. In addition, this study also suggests that APL may be a novel therapeutic target for IBD.

Endoplasmic reticulum stress is upregulated in inflammatory bowel disease and contributed TLR2 pathway-mediated inflammatory response

Objective Endoplasmic reticulum stress (ERS) and Toll-like receptor 2 (TLR2) signaling play an important role in inflammatory bowel disease (IBD); however, the link between TLR2 and ERS in IBD is unclear. This study investigated whether Thapsigargin (TG) -induced ER protein expression levels contributed to TLR2-mediated inflammatory response. Methods The THP-1 cells were treated with TLR2 agonist (Pam3CSK4), ERS inducer Thapsigargin (TG) or inhibitor (TUDCA). The mRNA expressions of TLR1-TLR10 were detected by qPCR. The production and secretion of inflammatory factors were detected by PCR and ELISA. Immunohistochemistry was used to detect the expressions of GRP78 and TLR2 in the intestinal mucosa of patients with Crohn’s disease (CD). The IBD mouse model was established by TNBS in the modeling group. ERS inhibitor (TUDCA) was used in the treatment group. Results The expression of TLRs was detected via polymerase chain reaction (PCR) in THP-1 cells treated by ERS agonist Thapsigargin (TG). According to the findings, TG could promote TLR2 and TLR5 expression. Subsequently, in TLR2 agonist Pam3CSK4 induced THP-1 cells, TG could lead to increased expression of the inflammatory factors such as TNF-α, IL-1β and IL-8, and ERS inhibitor (TUDCA) could block this effect. However, Pam3CSK4 did not significantly impact the GRP78 and CHOP expression. Based upon the immunohistochemical results, TLR2 and GRP78 expression were significantly increased in the intestinal mucosa of patients with Crohn’s disease (CD). For in vivo experiments, TUDCA displayed the ability to inhibit intestinal mucosal inflammation and reduce GRP78 and TLR2 proteins. Conclusions ERS and TLR2 is upregulated in inflammatory bowel disease, ERS may promote TLR2 pathway-mediated inflammatory response. Moreover, ERS and TLR2 signaling could be novel therapeutic targets for IBD.

SIX4 Activation in Inflammatory Response Drives the Transformation of Colorectal Epithelium into Inflammation and Tumor via Feedback-Enhancing Inflammatory Signaling to Induce Tumor Stemness Signaling.

Some colorectal cancer patients have experienced normal epithelial transformation into inflammatory and tumor states, but the molecular basis still needs to be further determined. The expression levels of SIX4 are gradually increased in dextran sodium sulfate (DSS) and azoxymethane (AOM)/DSS-induced colonic epithelial inflammation and tumors, respectively, in mice. Targeting SIX4 alleviates intestinal inflammation occurrence and reduces adenoma formation in mice. Clinical sample assays indicated that SIX4 is upregulated in inflammatory bowel disease (IBD) and colorectal cancer (CRC) tissues compared to normal colorectal tissues. In a subsequent study, we found that SIX4, transcriptionally activated by the proinflammatory IL-6/STAT3 signal, binds to c-Jun to transcribe IL-6, thus forming a positive IL-6/STAT3/SIX4/c-Jun feedback loop, which further induces intestinal inflammation occurrence. In addition, elevated SIX4 also induces the expression of DeltaNp63, rather than wild-type p63, by binding to its promoter and thus facilitates the activation of tumor stemness signals, which ultimately leads to the formation of colorectal cancer. Our study first observes that activated SIX4 in inflammation induction drives the transformation of colorectal epithelium into inflammation and tumor, which demonstrates SIX4 as a significant therapeutic target in IBD and colitis-associated colorectal cancer (CAC) and CRC pathogenesis.

Cytokine induced inflammatory bowel disease model using organ-on-a-chip technology

Over 2 million people in North America suffer from inflammatory bowel disease (IBD), a chronic and idiopathic inflammatory condition. While previous research has primarily focused on studying immune cells as a cause and therapeutic target for IBD, recent findings suggest that non-immune cells may also play a crucial role in mediating cytokine and chemokine signaling, and therefore IBD symptoms. In this study, we developed an organ-on-a-chip co-culture model of Caco2 epithelial and HUVEC endothelial cells and induced inflammation using pro-inflammatory cytokines TNF-α and IFN-γ. We tested different concentration ranges and delivery orientations (apical vs. basal) to develop a consistently inducible inflammatory response model. We then measured pro-inflammatory cytokines and chemokines IL-6, IL-8, and CXCL-10, as well as epithelial barrier integrity. Our results indicate that this model 1. induces IBD-like cytokine secretion in non-immune cells and 2. decreases barrier integrity, making it a feasible and reliable model to test the direct actions of potential anti-inflammatory therapeutics on epithelial and endothelial cells.

Antibody targeting TSLP suppresses DSS-induced colitis and activation of the JAK2/STAT5 pathway in mice.

There is currently no safe or effective treatment for inflammatory bowel disease (IBD), which is defined as recurrent and persistent intestinal inflammation. Thymic stromal lymphopoietin (TSLP) has been shown to be associated with the pathogenesis of IBD, and the JAK2/STAT5 signalling pathway has demonstrated much promise as a novel therapeutic target for IBD. In this study, we first evaluated levels of TSLP in dextran sodium sulphate (DSS)-induced IBD mice. Second, we applied tezepelumab, an anti-TSLP monoclonal antibody (20μg per mouse, intraperitoneally), to DSS-induced IBD mice and quantified the signs of histopathological change, intestinal inflammation, and integrity of the mucosal barrier. In addition, the effect of DSS and/or tezepelumab on the phosphorylation of the JAK/STAT pathway was investigated. TSLP expression levels were elevated in DSS-induced IBD mice, whereas TSLP antibody treatment suppressed the pathological features associated with IBD and alleviated intestinal inflammation and mucosal barrier disruption. Moreover, level of phosphorylated JAK2/STAT5 were increased in DSS-induced IBD mice, but were strongly decreased in the presence of tezepelumab. Our findings suggest that targeting TSLP via the JAK2/STAT5 signalling pathway may be an effective approach for the treatment of IBD.

Blocking the Apelin Receptor (APJ) Attenuates TNBS-Induced Colitis in Rats

Objective: The apelinergic system, consisting of apelin, ELABELA, and the apelin receptor (APJ), has a wide range of roles in physiological and pathophysiological processes in tissues. The effects of increased apelin and APJ as an indicator of damage in inflammatory conditions or as a compensatory mechanism are not fully clear in inflammatory bowel disease (IBD). This study was designed to assess the role of APJ in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model. Methods: Colitis in adult male Wistar rats were induced by intrarectally administered TNBS (30 mg b.w. in 50% ethanol). While the control group was treated with only saline to the colon, the TNBS+F13A and F13A groups received the APJ antagonist F13A (30 µg/kg/day, i.v.) for 3 days, starting immediately after TNBS or saline administration, respectively. Results: A decrease in body weight and an increase in colon weight/length ratio and stool consistency score were observed in the TNBS group. TNBS caused an increase in the myeloperoxidase (MPO) activity and the number of proinflammatory cytokines (TNF-α, IL-1β, and IL-6), as well as apelin production, leading to mucosal ulceration, necrosis, and submucosal edema in the colon. While F13A administration to the control did not cause any change in the colon, F13A administration immediately after TNBS greatly reduced the effects of TNBS. Conclusion: APJ is involved in the development of damage in colitis induced by TNBS. F13A reduces the level of damage, inflammatory cell infiltration, and MPO enzyme activity. APJ may be a therapeutic target in IBD.

The NRF2/Keap1 pathway as a therapeutic target in inflammatory bowel disease.

Oxidative stress (OS) is an important pathophysiological mechanism in inflammatory bowel disease (IBD). However, clinical trials investigating compounds directly targeting OS in IBD yielded mixed results. The NRF2 (nuclear factor erythroid 2-related factor 2)/Keap1 (Kelch-like ECH-associated protein 1) pathway orchestrates cellular responses to OS, and dysregulation of this pathway has been implicated in IBD. Activation of the NRF2/Keap1 pathway may enhance antioxidant responses. Although this approach could help to attenuate OS and potentially improve clinical outcomes, an overview of human evidence for modulating the NRF2/Keap1 axis and more recent developments in IBD is lacking. This review explores the NRF2/Keap1 pathway as potential therapeutic target in IBD and presents compounds activating this pathway for future clinical applications.

Emerging roles of host and microbial bioactive lipids in inflammatory bowel diseases.

The intestinal tract harbors diverse microorganisms, host- and microbiota-derived metabolites, and potentially harmful dietary antigens. The epithelial barrier separates the mucosa, where diverse immune cells exist, from the lumen to avoid excessive immune reactions against microbes and dietary antigens. Inflammatory bowel disease (IBD), such as ulcerative colitis and Crohn's disease, is characterized by a chronic and relapsing disorder of the gastrointestinal tract. Although the precise etiology of IBD is still largely unknown, accumulating evidence suggests that IBD is multifactorial, involving host genetics and microbiota. Alterations in the metabolomic profiles and microbial community are features of IBD. Advances in mass-spectrometry-based lipidomic technologies enable identification of changes in the composition of intestinal lipid species in IBD. Because lipids have a wide range of functions, including signal transduction and cell membrane formation, dysregulation of lipid metabolism drastically affects the physiology of the host and microorganisms. Therefore, a better understanding of the intimate interactions of intestinal lipids with host cells that are implicated in the pathogenesis of intestinal inflammation might aid in the identification of novel biomarkers and therapeutic targets for IBD. This review summarizes the current knowledge on the mechanisms by which host and microbial lipids control and maintain intestinal health and diseases. This article is protected by copyright. All rights reserved.

Blockade of IL-18 signaling downregulates homing of effector CD4+ T cells to the gut mucosa and provides protection from experimental IBD

Abstract The immunological complexity of inflammatory bowel disease (IBD) results in persistent intestinal inflammation in millions of patients. As an epithelial cell-derived cytokine essential in the differentiation of CD4+ T helper cells, interleukin 18 (IL-18) is emerging as a therapeutic target for IBD. When naïve CD4+ T cells are stimulated with IL-18, the production of IFNγ and differentiation of Th1 cells increase. IL18R1−/− CD4+ T cells produce less IFNγ and inflammatory cytokines compared to WT. To examine the viability of targeting IL-18 in vivo, colitis was induced in WT, IL18−/−, and IL18R1−/− mice by DSS. In both knockouts, lower proportions of IFNγ- and IL17-producing CD4+ T cells were observed in the colon along with lesser overall severity relative to WT. To further investigate, we examined the interplay of antigen presenting cells and CD4+ T cells in vitro. IL18R1−/− Th1 cells had decreased α4β7 and GPR15 expression when co-cultured with WT BMDCs. Meanwhile, IL18R1−/− Tregs had decreased IFNγ and CCR9 expression when co-cultured with WT BMDCs that were stimulated with LPS and retinoic acid, suggesting that IL-18 may play a role in the differential gut homing of CD4+ T cell subsets. When CD4+ T cells are transferred to Rag2−/−, mice receiving IL18R1−/− T cells possess significantly lower proportions of α4β7+ Th1 cells while the proportion of Tregs in the colon are increased. Treatment of mice with DSS or Mdr1a−/− colitis with an oral IL-18 inhibitor (20 mg/kg) resulted in decreased Th1 cells and neutrophils, lower histological scores and improved disease severity. From converging data, we deduce that inhibition of IL-18 may alleviate exacerbated immune responses associated with IBD, yielding a favorable therapeutic.

The HIF-prolyl hydroxylases have distinct and non-redundant biological roles in the pathogenesis of colitis-associated cancer

Colitis-associated colorectal cancer (CAC) is a severe complication of inflammatory bowel disease (IBD). HIF-prolyl hydroxylases (PHD1, PHD2, and PHD3) control cellular adaption to hypoxia and are considered promising therapeutic targets in IBD. However, their relevance in the pathogenesis of CAC remains elusive. We induced CAC in Phd1-/-, Phd2+/-, Phd3-/-, and WT mice with azoxymethane (AOM) and dextran sodium sulfate (DSS). Phd1-/- mice were protected against chronic colitis and displayed diminished CAC growth compared to WT mice. In Phd3 -/- mice, colitis activity and CAC growth remained unaltered. In Phd2+/- mice, colitis activity was unaffected, but CAC growth was aggravated. Mechanistically, Phd2 deficiency (i) increased the number of tumor-associated macrophages (TAMs) in AOM/DSS-induced tumors, (ii) promoted the expression of EGFR ligand epiregulin ( Ereg) in macrophages, and (iii) augmented signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling which at least in part contributed to aggravated tumor cell proliferation in colitis-associated tumors. Consistently, Phd2 deficiency in hematopoietic ( Vav:Cre-Phd2f/f) but not in intestinal epithelial cells ( Villin:Cre-Phd2f/f) increased CAC growth. In conclusion, the three different PHD isoenzymes have distinct and non-redundant, either promoting (PHD1), diminishing (PHD2), or neutral effects (PHD3) on CAC growth. KBK received funding from the German Cancer Aid. MJS. received funding from the German Research Foundation (DFG; STR 1570/1-1) and the Braun Foundation (Braun®; BBST-D-18-00018). MSch received funding from the German Federal Ministry of Education and Research (BMBF; 031L0084). JMH received funding from the Heidelberg Stiftung Chirurgie. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.