Disease Severity In Models Research Articles

Development of dual GPBAR1 agonist and RORγt inverse agonist for the treatment of inflammatory bowel diseases

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are chronic disorders characterized by dysregulated immune response and persistent inflammation. Recent studies suggest that bile acid receptors, particularly GPBAR1, and the transcription factor RORγt play critical roles in modulating intestinal inflammation. This study evaluates the therapeutic potential of PBT002, a dual GPBAR1 agonist and RORγt inverse agonist, in IBD models. The effects of PBT002 were assessed through in vitro and in vivo experiments. Macrophages and T lymphocytes obtained from the buffy coat were exposed to PBT002 to evaluate its immunomodulatory activity. The beneficial effects in vivo were evaluated in mouse models of colitis induced by TNBS, DSS or DSS + IL-23 using also a Gpbar1 knock-out male mice. PBT002 exhibited an EC50 of 1.2 µM for GPBAR1 and an IC50 of 2.8 µM for RORγt. In in vitro, PBT002 modulated macrophage polarization towards an anti-inflammatory M2 phenotype and reduced Th17 cell markers while increasing Treg markers. In the TNBS-induced colitis model, PBT002 reduced weight loss, CDAI, and colon damage, while it modulated cytokine gene expression towards an anti-inflammatory profile. In GPBAR1-/-, the anti-inflammatory effects of PBT002 were attenuated, indicating partial GPBAR1 dependence. RNA sequencing revealed significant modulation of inflammatory pathways by PBT002. In DSS+IL-23 induced colitis, PBT002 mitigated disease exacerbation, reducing pro-inflammatory cytokine levels and immune cell infiltration. In conclusion, PBT002, a GPBAR1 agonist and RORγt inverse agonist, modulates both the innate and adaptive immune responses to reduce inflammation and disease severity in models of IBD.

Aryl hydrocarbon receptor ligand supplementation impacts colitis-associated depressive-like behavior

Abstract Colitis is an inflammatory bowel disease (IBD) with increased incidences of depression in patients. The mechanisms that define this comorbidity remain poorly understood. Our lab previously showed supplementation with indole-3-carbinol (I3C), an aryl hydrocarbon receptor (AhR) ligand, can reduce disease severity in models of colitis. We aimed to determine the behavioral impact I3C supplementation has on colitis-induced depression via alterations in the gut metabolome. Colitis was induced in using the dextran sodium sulfate (DSS) method and treatment groups were given a regimen of 40 mg/kg I3C as previously reported. Untargeted metabolomic studies revealed quinolinic acid (QA), a metabolite produced by the kynurenine (KYN) pathway and linked to depression, was found to be significantly reduced in I3C-treated mice when compared to colitis controls. To determine the effects of I3C and QA modulation on depressive-like behavior, colitis mice were treated with either I3C or an inhibitor of a major enzyme involved in QA production. Depressive-like behavior was measured using the Tail Suspension Test (TST) method, along with evaluation of neural biomarkers of depression (dopamine, BDNF, GFAP) and stabilization of the blood brain barrier (BBB). Results showed I3C reduced depressive-like behavior and altered select biomarkers associated with depression. These studies provide evidence that AhR can be a potential therapeutic target for both colitis and colitis-associated depression.

Targeting activins and inhibins to treat reproductive disorders and cancer cachexia.

Although originally characterised as proteins involved in the control of reproductive function, activins, and to a lesser degree inhibins, are also important regulators of homeostasis in extragonadal tissues. Accordingly, disrupted inhibin/activin expression can have detrimental effects not only for fertility and fecundity, but also for the regulation of muscle, fat and bone mass. Indeed, only recently, two complementary mouse models of inhibin designed to lack bioactivity/responsiveness, revealed that inhibin A/B deficiency during pregnancy, restricts embryo and foetal survival. Conversely, hyper elevated levels of activin A/B, as are frequently observed in patients with advanced cancers, can not only promote gonadal tumour growth but also cancer-cachexia. As such, it is not surprising that inhibin/activin genetic variations or altered circulating levels have been linked to reproductive disorders and cancer. Whilst some of the detrimental health effects associated with disrupted inhibin/activin levels can be attributed to accompanied changes in circulating follicle stimulating hormone (FSH) levels, there is now abundant evidence that activins, in particular, have fundamental FSH-independent tissue homeostatic roles. Increased understanding of inhibin/activin activity, garnered over several decades, has enabled the development of targeted therapies with applications for both reproductive and extra-gonadal tissues. Inhibin- or activin-targeted technologies have been shown not just to enhance fertility and fecundity, but also to reduce disease severity in models of cancer cachexia. Excitingly, these technologies are likely to benefit human medicine and be highly valuable to animal breeding and veterinary programs.

Soluble syndecan-3 binds chemokines, reduces leukocyte migration in vitro and ameliorates disease severity in models of rheumatoid arthritis

BackgroundSyndecans are heparan sulfate proteoglycans that occur in membrane-bound or soluble forms. Syndecan-3, the least well-characterised of the syndecan family, is highly expressed on synovial endothelial cells in rheumatoid arthritis patients. Here, it binds pro-inflammatory chemokines with evidence for a role in chemokine presentation and leukocyte trafficking into the joint, promoting the inflammatory response. In this study, we explored the role of soluble syndecan-3 as a binder of chemokines and as an anti-inflammatory and therapeutic molecule.MethodsA human monocytic cell line and CD14+ PBMCs were utilised in both Boyden chamber and trans-endothelial migration assays. Soluble syndecan-3 was tested in antigen-induced and collagen-induced in vivo arthritis models in mice. ELISA and isothermal fluorescence titration assays assessed the binding affinities. Syndecan-3 expression was identified by flow cytometry and PCR, and levels of shedding by ELISA.ResultsUsing in vitro and in vivo models, soluble syndecan-3 inhibited leukocyte migration in vitro in response to CCL7 and its administration in murine models of rheumatoid arthritis reduced histological disease severity. Using isothermal fluorescence titration, the binding affinity of soluble syndecan-3 to inflammatory chemokines CCL2, CCL7 and CXCL8 was determined, revealing little difference, with Kds in the low nM range. TNFα increased cell surface expression and shedding of syndecan-3 from cultured human endothelial cells. Furthermore, soluble syndecan-3 occurred naturally in the sera of patients with rheumatoid arthritis and periodontitis, and its levels correlated with syndecan-1.ConclusionsThis study shows that the addition of soluble syndecan-3 may represent an alternative therapeutic approach in inflammatory disease.

Astrocytes to the rescue! Glia limitans astrocytic endfeet control CNS inflammation.

The blood-brain barrier (BBB) and the glia limitans serve to prevent the migration of cells and other large molecules from the blood into the CNS. Neuroinflammatory diseases are characterized by disruption of the BBB and increased leukocyte infiltration into the CNS. In this issue of the JCI, Horng and colleagues demonstrate that astrocytes of the glia limitans induce tight junction formation in response to inflammatory cues, thereby tightening the border to limit the number of activated T cells infiltrating the CNS. Moreover, preventing the formation of this inducible barrier in mice increased disease severity in models of neuroinflammation. Together, the results of this study indicate that the inducible barrier of the glia limitans should be further explored as a therapeutic target.

Generation and characterization of a mouse LIGHT specific inhibitor in a murine model of colitis (THER4P.891)

Abstract LIGHT (TNFSF14, CD258) is a member of the TNF superfamily that is expressed on activated T cells, immature DCs, macrophages, and NK cells. LIGHT interacts with its receptors (HVEM and LTβR) and is reported to provide co-stimulatory and pro-inflammatory signals to T cells, B cells, DCs, and macrophages. Numerous studies have implicated the pro-inflammatory effects of LIGHT as an important contributor to disease severity in models of inflammatory bowel disease and fibrosis. However, the inhibitors used in many of these studies (e.g. LTβR-Ig and HVEM-Ig) are not specific for LIGHT, and are likely to impact other pathways such as LTαβ and BTLA. Our focus was to develop domain antibodies (dAbs) that specifically block LIGHT-HVEM and LIGHT-LTβR interactions to better understand the therapeutic potential of LIGHT specific blockade. We were able to develop a mouse LIGHT specific inhibitor that potently blockades LIGHT-HVEM and LIGHT-LTβR interactions in vitro. Notably, this dAb had little effect when used as a monotherapy in a murine model of colitis, but when combined with CD40 blockade showed a high degree of efficacy (equivalent to CTLA4-Ig treatment). These data suggest that LIGHT monotherapy may not be sufficient to impact disease severity, but LIGHT blockade may have potential as part of a combination approach.