title: Control of intracellular trafficking of ICAM-1-targeted nanocarriers by endothelial Na+/H+ exchanger proteins.
abstract: Targeting nanocarriers (NC) loaded by antioxidant enzymes (e.g., catalase) to endothelial cell adhesion molecules (CAM) alleviates oxidative stress in the pulmonary vasculature. However, antioxidant protection is transient, since CAM-targeted catalase is internalized, delivered to lysosomes, and degraded. To design means to modulate the metabolism and longevity of endothelial cell (EC)-targeted drugs, we identified and manipulated cellular elements controlling the uptake and intracellular trafficking of NC targeted to ICAM-1 (anti-ICAM/NC). BAPTA, thapsigargin, amiloride, and EIPA inhibited anti-ICAM/NC uptake by EC and actin rearrangements induced by anti-ICAM/NC (required for uptake), suggesting that member(s) of Na(+)/H(+) exchanger family proteins (NHE) regulate these processes. Consistent with this hypothesis, an siRNA specific for the plasmalemma NHE1, but not the endosome-associated NHE6, inhibited actin remodeling induced by anti-ICAM/NC and internalization. Anti-ICAM/NC binding to EC stimulated formation of a transient ICAM-1/NHE1 complex. One hour after uptake, ICAM-1 dissociated from NHE1, and anti-ICAM/NC were transported to NHE6-positive vesicles en route to lysosomes. Inhibition of PKC (an activator of intracellular NHE) accelerated nanocarrier lysosomal trafficking. In contrast, monensin, which enhances the endosomal sodium influx and proton efflux maintained by NHE6, inhibited delivery of anti-ICAM/NC to lysosomes by switching their trafficking to a plasma membrane recycling pathway. This markedly prolonged the protective effect of catalase-coated anti-ICAM/NC. Therefore, 1) NHE1 and NHE6 regulate distinct phases of anti-ICAM/NC uptake and trafficking; 2) pharmacological agents affecting these regulatory elements alter the itinerary of anti-ICAM/NC intracellular trafficking; and 3) these agents modulate duration of the therapeutic effects of targeted drugs.
authors.affiliation: Institute for Environmental Medicine, University of Pennsylvania School of Medicine, 1 John Morgan/6068, 3620 Hamilton Walk, Philadelphia, PA 19104, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Muro
authors.forename: Madalina
authors.initials: M
authors.lastname: Mateescu
authors.forename: Christine
authors.initials: C
authors.lastname: Gajewski
authors.forename: Mary
authors.initials: M
authors.lastname: Robinson
authors.forename: Vladimir R
authors.initials: VR
authors.lastname: Muzykantov
authors.forename: Michael
authors.initials: M
authors.lastname: Koval
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D001692:Biological Transport; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D004705:Endocytosis; D004730:Endothelium, Vascular / Q000502:physiology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism / Q000502:physiology*; D007700:Kinetics; D049329:Nanostructures; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology*; D019284:Thapsigargin / Q000493:pharmacokinetics
chemical_list: D017923:Sodium-Hydrogen Exchangers; C069139:growth factor-activatable Na-H exchanger NHE-1; D018799:Intercellular Adhesion Molecule-1; D004533:Egtazic Acid; D019284:Thapsigargin; D000584:Amiloride; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; C039614:ethylisopropylamiloride