Macrophage plasticity as a therapeutic target in inflammatory bowel disease: Immunomodulatory and regenerative strategies.

Inflammatory bowel disease (IBD), which mainly includes Crohn's disease and ulcerative colitis, is a chronic inflammatory disorder of the gastrointestinal tract characterized by recurrent episodes of intestinal inflammation. The development of IBD is influenced by multiple factors, including genetic predisposition, intestinal dysbiosis, epithelial barrier impairment, and abnormal immune activation. Among innate immune cells, macrophages are key regulators of intestinal immune homeostasis and are involved in inflammatory responses, tissue remodeling, and mucosal repair. Their ability to adopt different functional states in response to local environmental signals has made them an important focus of current therapeutic research in IBD. Traditionally, macrophages have been classified into pro-inflammatory M1 and anti-inflammatory M2 phenotypes. However, recent findings from single-cell transcriptomic and spatial analyses suggest that intestinal macrophages represent a far more diverse and dynamic population than this simplified classification implies. Multiple macrophage subsets with inflammatory, regulatory, reparative, and fibrosis-associated functions coexist within the intestinal microenvironment and contribute differently to disease progression and tissue healing. These observations highlight the importance of developing more selective and targeted macrophage-based therapeutic approaches. In this review, we discuss the current understanding of macrophage plasticity and its role in the pathogenesis of IBD. Particular attention is given to newer macrophage-targeted therapeutic strategies, including adoptive macrophage transfer, engineered macrophages, receptor-targeted therapies, nanoparticle-based delivery systems, microbiome modulation, microbial metabolite regulation, gene-editing approaches, organoid technologies, and biomaterial-assisted platforms. We also examine the contribution of macrophages to epithelial regeneration, mucosal healing, fibrosis, and intestinal tissue remodeling. In addition, we address several major challenges that currently limit the clinical translation of macrophage-targeted therapies. A better understanding of macrophage biology, together with continued advances in immunology, regenerative medicine, microbiome research, and biomaterials science, may support the development of more precise and personalized therapeutic strategies for patients with IBD.