Albumin binding domain fusion improved the therapeutic efficacy of Inhibitor of Differentiation-2 protein in colitis mice.

Aims: The human Inhibitor of Differentiation-2 (hID2) protein is a promising candidate for the treatment of colitis. However, its relatively low molecular weight limits its clinical application. To extend the therapeutic half-life, an albumin-binding domain (ABD), known for its high affinity for human serum albumin (HSA), was fused to hID2, resulting in a recombinant ABD-hID2. The anti-colitis bioactivity of ABD-hID2 than that of hID2 was evaluated in this study.

Main Methods: Western blotting, size-exclusion high-performance chromatography, HSA binding assay, and pharmacokinetic studies were used to characterise ABD-hID2, which was induced by dextran sulfate sodium salt (DSS), Citrobacter rodentium (CR), and ABD-hID2 and hID2. The Disease Activity Index, histological pathologies, inflammatory response, Alcian blue or tuft cell staining, and tight junction proteins were determined. Alterations in the intestinal microbiota after ABD-hID2 treatment were analysed via 16S rRNA gene sequencing.

Key Findings: Compared with hID2, ABD-hID2 exhibited a decreased dimer complex, bound to HSA with high affinity, and demonstrated an extended blood retention time in vivo. Consequently, ABD-hID2 exhibited increased therapeutic efficacy in both DSS- and CR-induced colitis mouse models, as evidenced by the alleviation of colitis symptoms, preservation of goblet and tuft cell functions, restoration of the intestinal mucus barrier, and suppression of abnormal immune-inflammatory responses. Additionally, the modulation of the gut microbiota may play a role in the protective effects of ABD-hID2 in mice with CR-induced ulcerative colitis.

Significance: ABD-hID2 enhances the bioactivity of hID2 and has the potential for further development as a treatment for colitis.