Purpose: The feasibility of utilizing the cell surface chemokine receptor CXCR4 for human immunodeficiency virus (HIV) entry inhibition and as an intracellular portal for targeted drug delivery was evaluated.
Methods: 4DV3, a novel tetrameric peptide ligand derived from anti-HIV chemokine vMIP-II, was synthesized and conjugated to various probes (fluorescein isothiocyanate (FITC) or biotin) and cargos with sizes ranging from 10 to 70 nm (polyethylene glycol (PEG), streptavidin, and polymeric nanoparticle). TZM-bl cells, a CXCR4-expressing reporter cell line that contains the luciferase gene sensitive to HIV-1 infection, were used to study CXCR4-specific inhibition of HIV entry by 4DV3, as well as 4DV3-mediated cellular uptake of nanocarriers. For chemotaxis assay, CXCR4-expressing Sup-T1 cells were used.
Results: 4DV3 conjugated probes inhibited HIV-1 entry into the CXCR4-expressing reporter cell line TZM-bl (IC50 at 553 nM). 4DV3 also inhibited binding of anti-CXCR4 antibody 44708 to TZM-bl cells with nanomolar potency, while the small-molecule CXCR4 antagonist AMD3100 did not. In the Sup-T1 cell chemotaxis assay, the 4DV3 ligand functioned as a CXCR4 allosteric enhancer. In addition, 4DV3 ligand-conjugated cargos with sizes ranging from 10 to 70 nm were taken up into CXCR4-expressing Sup-T1 and TZM-bl cells, demonstrating that CXCR4 could serve as a drug delivery portal for nanocarriers. The uptake of 4DV3 functionalized nanocarriers combined with the allosteric interaction with CXCR4 suggests enhanced endocytosis occurs when 4DV3 is the targeting ligand.
Conclusion: The current results indicate that 4DV3 might serve as a prototype for a new type of dual function ligand that acts as a HIV-1 entry inhibitor and a CXCR4 drug delivery targeting ligand.
Matthew Palombo– Rutgers University Ernest Mario School of Pharmacy
Xiaoping Zhang– Rutgers University Ernest Mario School of Pharmacy
Zoltan Szekely– Assistant Research Professor, Rutgers University Ernest Mario School of Pharmacy
Patrick Sinko– Distinguished Professor, Rutgers University Ernest Mario School of Pharmacy