Emerging therapeutic targets and strategies in Crohn's disease

Targeting mucosal healing in Crohn's disease: efficacy of novel pathways and therapeutic targets

INTRODUCTION

Crohn's disease (CD) is a chronic inflammatory bowel disease affecting the entire gastrointestinal tract with a progressive and relapsing course. Achieving mucosal healing has emerged as a critical therapeutic goal, as it is associated with sustained clinical remission, reduced hospitalizations, and fewer surgery rates. Therefore, targeting mucosal healing is essential for long-term control in CD.

AREAS COVERED

This review evaluates the efficacy of novel biologic therapies and small molecules in inducing mucosal healing, specifically targeting pathways like IL-12/23, IL-23, α4β7 integrins, Janus kinase 1 (JAK1), and sphingosine-1-phosphate receptor (S1PR) in adults (≥18 years) with moderate-to-severe CD. The rationale for selecting these specific pathways is their central role in modulating key inflammatory processes implicated in CD pathogenesis. We compare these therapies with placebo for both induction and maintenance of remission, based on a PubMed literature review for published articles and ClinicalTrials.gov for ongoing trials.

EXPERT OPINION

Upadacitinib and anti-IL23p19 agents (risankizumab, guselkumab and mirikizumab) are promising advanced non-TNF-targeting therapies for inducing endoscopic remission and mucosal healing but further studies are needed to integrate mucosal healing into a broader definition of endoscopic response, with a unified and precise definition.

Repeated Fecal Microbial Transplantations and Antibiotic Pre-Treatment Are Linked to Improved Clinical Response and Remission in Inflammatory Bowel Disease: A Systematic Review and Pooled Proportion Meta-Analysis

The response of patients with inflammatory bowel disease (IBD) to fecal microbial transplantation (FMT) has been inconsistent possibly due to variable engraftment of donor microbiota. This failure to engraft has resulted in the use of several different strategies to attempt optimization of the recipient microbiota following FMT. The purpose of our study was to evaluate the effects of two distinct microbial strategies-antibiotic pre-treatment and repeated FMT dosing-on IBD outcomes. A systematic literature review was designed and implemented in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A medical librarian conducted comprehensive searches in MEDLINE, Embase, Scopus, Web of Science Core Collection, and Cochrane Library on 25 November 2019 and updated on 29 January 2021. Primary outcomes of interest included comparing relapse and remission rates in patients with IBD for a single FMT dose, repeated FMT dosages, and antibiotic pre-treatment groups. Twenty-eight articles (six randomized trials, 20 cohort trials, two case series) containing 976 patients were identified. Meta-analysis revealed that both repeated FMT and antibiotic pre-treatment strategies demonstrated improvements in pooled response and remission rates. These clinical improvements were associated with increases in fecal microbiota richness and α-diversity, as well as the enrichment of several short-chain fatty acid (SCFA)-producing anaerobes including Bifidobacterium, Roseburia, Lachnospiraceae, Prevotella, Ruminococcus, and Clostridium related species.

Potential role of MRN-100, an iron-based compound, in upregulating production of cytokine IL-10 in human dendritic cells to promote an anti-inflammatory response in vitro

The hydroferrate fluid MRN-100, an iron-based compound with potent antioxidant characteristics, was examined to identify its possible anti-inflammatory effects on human dendritic cells (DCs) in vitro. Human monocyte-derived DCs were treated with MRN-100 at two concentrations (50 and 100 μL/mL) for 24 h and then stimulated with or without lipopolysaccharides (LPS). The expression of DC maturation markers was assessed by flow cytometry and the production of cytokines was determined by enzyme-linked immunosorbent assay (ELISA). Functional assay was performed by co-culturing MRN-100-treated and untreated DCs with allogeneic naïve CD4+ T cells and assaying the T cells' cytokine production. Results show that treatment with MRN-100 significantly upregulated the co-stimulatory molecules CD80 and CD86 and increased human leukocyte antigen-DR (HLA-DR) though not significantly. MRN-100 treatment also significantly increased the production of the anti-inflammatory cytokine interleukin (IL)-10. On the other hand, MRN-100 significantly induced the secretion of pro-inflammatory cytokines such as IL-6 only at high concentrations. Furthermore, DCs pretreated with MRN-100 and either stimulated or not with LPS were able to prime CD4+ T cells to secrete significant amounts of IL-10 while inhibiting the secretion of pro-inflammatory cytokine tumor necrosis factor (TNF)-α. These results indicate that MRN-100 is a powerful anti-inflammatory agent that promotes the generation of an anti-inflammatory immune response in vitro. MRN-100 could be beneficial for treating patients with inflammatory diseases, including arthritis and type 1 diabetes, and its potential benefits should be examined in clinical trials.

Absence of specific alternatively spliced exon of CD44 in macrophages prevents colitis

CD44 is a transmembrane molecule appearing in numerous isoforms generated by insertions of alternatively spliced variant exons (CD44v) and having various binding partners. CD44v7 on T cells was proposed to promote colitis by preventing T-cell apoptosis. Here we demonstrate that Cd44v7-deficient T cells - like Cd44 wild-type (Cd44^WT) T cells - provoked disease in two different colitis models: the model induced by CD4⁺CD45RB^high T-cell transfer into Rag2-deficient mice and a new model based on ovalbumin (OVA)-specific T-cell transfer into Rag-sufficient, OVA-challenged mice. In contrast, CD44v7 absence on macrophages in recipient mice prevented colitis. Prevention was associated with the downregulation of signal transducer and activator of transcription 3 (STAT3)-activating and Foxp3-counteracting interleukin-6 (IL-6), lower numbers of phospho-STAT3-containing lymphocytes, and higher Foxp3⁺ T-cell counts in the colon. Consequently, the protected colons showed lower IL-12, IL-1β expression, and decreased interferon-γ levels. Importantly, stimulation of T cells by Cd44v7-deficient macrophages induced upregulation of Foxp3 in vitro, while cotransfer of Cd44^WT macrophages into Cd44v7-deficient mice reduced Foxp3⁺ T-cell counts and caused colitis. Accordingly, the CD44v7 ligand osteopontin, whose levels were elevated in Crohn's disease, specifically induced IL-6 in human monocytes, a cytokine also increased in these patients. We suggest macrophage-specific targeting of the CD44v7 pathway as a novel therapeutic option for Crohn's disease.