Hypoxia-responsive hybrid nanoparticles loaded with fingolimod and colistin against multidrug-resistant Klebsiella pneumoniae with mature biofilm

Abstract

Multidrug-resistant Klebsiella pneumoniae (MDR-KP) is characterized by high mortality and risk of nosocomial transmission, and biofilm constitutes the primary challenge in the treatment of its implant-associated and refractory pulmonary infections. Notably, the hypoxic microenvironment and the physical barrier of biofilm leading to the increased tolerance of the bacteria to antibiotics. Herein, a hypoxia-responsive hybrid nanoparticle (CHLip@FLD/COL) loaded separately with anti-biofilm candidate fingolimod (FLD) and antibiotic colistin (COL) is achieved targeting antibacterial efficacy against MDR-KP in vitro and in vivo. CHLip@FLD/COL is composed of hybridizing hypoxia-responsive lipids (HLipid) and lipid A targeting materials DSPE-mPEG-COL. HLipid is synthesized by hexadecanedioic acid esterified with nitroimidazole, while DSPE-mPEG is coupling with vector COL via amide reaction. The relative level of extracellular polymeric substances and the NIR-IIb sO₂ images of the infection site are used as indicators to establish mature biofilm models. CHLip@FLD/COL readily releases FLD and COL in hypoxic conditions, and its MIC against MDR-KP is only one-sixteenth of that when COL is used alone in vitro. The nanoparticle exhibits bacterial targeting ability and antibacterial effect in the pulmonary infection and biofilm infection mice models. Bacterial loads eliminated by 4 Log₁₀ CFU and 2 Log₁₀ CFU, respectively. The strategy provides a valuable reference for the treatment of refractory infections caused by MDR-KP.