A shikonin-based self-assembled nanomedicine alleviates DSS-induced colitis involving HDC-associated histamine regulation and gut microbiota modulation.

Ulcerative colitis (UC) is a chronic inflammatory disorder of the intestine characterized by recurrent episodes. Current therapies exhibit limited efficacy and raise safety concerns. This study aimed to enhance the water solubility of the natural compound shikonin and improve its therapeutic efficacy by developing novel metal-phenolic nanoparticles. Zn-shikonin-PEG hybrid nanoparticles (Zn-SHK-PEG NPs) were synthesized by coordinating Zn2+ with shikonin and functionalizing the complex with polyethylene glycol (PEG). Dextran sulfate sodium (DSS)-induced colitis was employed to evaluate the therapeutic potential and mechanisms of the nanoparticles. Treatment with Zn-SHK-PEG NPs markedly alleviated weight loss and colon shortening, decreased the disease activity index (DAI), and reduced histopathological injury. Mechanistic investigations suggested that the nanoparticles reduced histidine decarboxylase (HDC) expression, which was associated with PKM2 regulation, accompanied by decreased histamine (HA) levels and suppressed inflammation. Furthermore, Zn-SHK-PEG NPs altered the gut microbiota composition, including enrichment of Akkermansia muciniphila, which may also contribute to the overall therapeutic effect. In summary, Zn-SHK-PEG NPs ameliorated DSS-induced colitis, and the therapeutic effects were associated with the regulation of the HDC/histamine axis, suppression of inflammatory responses, and modulation of gut microbiota. These findings suggest that Zn-SHK-PEG NPs may represent a potential strategy for ulcerative colitis treatment.