Nanobodies for inflammatory bowel disease: Miniaturizing solutions.

Inflammatory bowel disease (IBD), comprising Crohn's disease and ulcerative colitis, represents a group of chronic, relapsing intestinal disorders of complex pathogenesis and increasing global incidence. Current therapeutic strategies, including corticosteroids, immunosuppressants, and biologics, often face limitations such as inadequate efficacy, systemic side effects, and high cost, leaving a significant proportion of patients without satisfactory treatment outcomes. Nanobodies, single-domain antibody fragments derived from camelid heavy-chain antibodies, have emerged as promising novel therapeutic modality due to their unique pharmacological properties. Their small molecular size (∼15 kDa), high stability, superior tissue penetration, and cost-effective production offer distinct advantages over conventional monoclonal antibodies. Mechanistically, nanobodies are posited to demonstrate dual therapeutic functions: selective modulation of pathogenic T cell subsets and key inflammatory mediators (e.g., TNF-α, IL-6, IL-17), coupled with restoration of intestinal epithelial barrier integrity. This review provides a comprehensive analysis of the nanobody landscape in IBD, encompassing their therapeutic and diagnostic applications. A comparative assessment with existing modalities highlights the distinctive niche of nanobodies. Despite this promise, clinical advancement is confronted by challenges including transient in vivo half-life, immunogenicity concerns, and target prediction accuracy. This review critically evaluates these hurdles and discusses cutting-edge engineering strategies designed to overcome them, such as AI-powered protein design and novel delivery platforms like engineered bacteria and small extracellular vesicles. Finally, the discussion extends to the clinical translation pipeline, ranging from half-life extension technologies to emerging clinical candidates, and concludes with future perspectives on the evolving role of nanobodies in personalized IBD therapy.