Redox-Responsive Hyaluronic Acid-Tacrolimus Conjugate: Synthesis, Characterization, and In Vitro Immunosuppressive Activity

A redox-responsive macromolecular prodrug of tacrolimus, HA-ss-Tac, was constructed by conjugation of tacrolimus (TAC, FK506) through its succinate ester to cyst amine-modified hyaluronic acid (HA-Cys), and its physicochemical properties and immunosuppressive activity were studied. The synthesized HA-ss-TAC was determined to contain 8% of chemically loaded TAC with significantly enhanced water solubility. The release study showed a sustained release of drug through slow degradation of linker-drug bonds. In vitro inhibition of proliferation of T-and B-lymphocytes was almost comparable to that of TAC, implying that the biologically active compound could be released from the conjugate. The polymeric prodrug lacks obvious cytotoxicity on Raw 264.7 macrophages and significantly suppressed the production of inflammatory cytokines IL-2 and IL-1 beta by LPS-activated cells. Additionally, the cellular uptake study of the FITC-labeled conjugate confirmed the HA receptor-mediated internalization of the conjugate into targeted cells, thus avoiding systemic side effects. Taken together, the HA-ss-TAC prodrug could be an optimal prodrug for intravenous administration based on this preliminary data and can be expected to have improved therapeutic efficacy.

Automated summary

A redox-responsive macromolecular prodrug of tacrolimus, called HA-ss-Tac, was synthesized and its physicochemical properties and immunosuppressive activity were investigated. The prodrug exhibited enhanced water solubility and sustained release of the drug. It showed similar inhibition of lymphocyte proliferation compared to tacrolimus and suppressed the production of inflammatory cytokines. The prodrug was taken up by target cells through receptor-mediated internalization, suggesting its potential as an improved therapy with reduced side effects.