Novel Therapeutic Strategies for Active Crohn's Disease: Targeting Pathobionts and Host-Microbe Interactions

Crohn's disease (CD) is a chronic inflammatory disorder characterized by complex interactions among genetic susceptibility, environmental factors, dysregulated immune responses, and alterations of the intestinal microbiota. Although corticosteroids, immunomodulators, biologics, and advanced small-molecule therapies remain central to disease management, a substantial proportion of patients experience primary non-response, loss of response, or treatment-related adverse effects. This has stimulated interest in complementary therapeutic strategies targeting host-microbe interactions and intestinal microbial homeostasis. This review critically examines emerging microbiome-directed approaches for CD, with particular emphasis on pathobionts such as adherent-invasive Escherichia coli (AIEC). We discuss the available evidence for antibiotics, antimicrobial peptides (AMP), gut bacteriophages, fecal microbiota transplantation (FMT), and selected nutraceutical and dietary interventions. While some approaches show promising biological or clinical signals, the strength of evidence varies considerably, ranging from in vitro and animal studies to randomized clinical trials and meta-analyses. Antibiotic therapies targeting intestinal pathogens have shown heterogeneous results, suggesting the need for pathogen-guided and intracellularly active antimicrobial strategies. Novel approaches, including AIEC-specific phages and AMP-based interventions, represent promising microbiome-sparing alternatives capable of selectively modulating disease-associated microorganisms. Furthermore, FMT and nutraceuticals may contribute to restoring microbial balance and strengthening intestinal homeostasis, although their efficacy requires further validation in controlled clinical trials. Overall, these strategies support a transition toward precision medicine approaches integrating microbial profiling, host immune characterization, and targeted antimicrobial interventions to improve therapeutic outcomes in CD.