Nanoparticle-based therapeutics of inflammatory bowel diseases: a narrative review of the current state and prospects

Inflammatory bowel disease (IBD), such as Crohn disease and ulcerative colitis, are chronic relapsing disorders of the gastrointestinal tract. Characterized pathologically by intestinal inflammation and epithelial injury, great challenges exist for the treatment of IBD due to its complicated etiology and incurable nature. Traditional strategies rely on frequent and long-term administration of high dosages of anti-inflammatory drugs, which inevitably cause side effects. Therefore, novel therapeutic methods and drug delivery systems capable of improving therapeutic effect while simultaneously decreasing side effects need to be developed. The emergence of nanotechnology provides alternative approaches for diagnosis and treatment of IBD, as nanoparticles (NPs) have unique physicochemical properties such as targeting to the site of inflammation and the ability to alter the pharmacokinetics of traditional drugs. This review first introduces the pathophysiological features and microenvironment of IBD, and then summarizes different strategies and mechanisms of NP-based colon-targeted drug delivery systems, including size-dependent, multi-stimuli responsive, active targeting, intestinal microbiota-related, and novel natural-derived NP-mediated drug delivery systems. We also discuss applications of nanozymes and NP-based imaging in diagnostics and treatment of IBD. Finally, challenges and prospects in the field are proposed to promote the development of targeted drug delivery for IBD treatment.