Distinct subcellular trafficking resulting from monomeric vs multimeric targeting to endothelial ICAM-1: implications for drug delivery.

Abstract

Ligand-targeted, receptor-mediated endocytosis is commonly exploited for intracellular drug delivery. However, cells-surface receptors may follow distinct endocytic fates when bound by monomeric vs multimeric ligands. Our purpose was to study this paradigm using ICAM-1, an endothelial receptor involved in inflammation, to better understand its regulation and potential for drug delivery. Our procedure involved fluorescence microscopy of human endothelial cells to determine the endocytic behavior of unbound ICAM-1 vs ICAM-1 bound by model ligands: monomeric (anti-ICAM) vs multimeric (anti-ICAM biotin-streptavidin conjugates or anti-ICAM coated onto 100 nm nanocarriers). Our findings suggest that both monomeric and multimeric ligands undergo a similar endocytic pathway sensitive to amiloride (∼50% inhibition), but not inhibitors of clathrin-pits or caveoli. After 30 min, ∼60-70% of both ligands colocalized with Rab11a-compartments. By 3-5 h, ∼65-80% of multimeric anti-ICAM colocalized with perinuclear lysosomes with ∼60-80% degradation, while 70% of monomeric anti-ICAM remained associated with Rab11a at the cell periphery and recycled to and from the cell-surface with minimal (<10%) lysosomal colocalization and minimal (≤15%) degradation. In the absence of ligands, ICAM-1 also underwent amiloride-sensitive endocytosis with peripheral distribution, suggesting that monomeric (not multimeric) anti-ICAM follows the route of this receptor. In conclusion, ICAM-1 can mediate different intracellular itineraries, revealing new insight into this biological pathway and alternative avenues for drug delivery.

• Authors: Rasa Ghaffarian, Silvia Muro
• Journal: Molecular pharmaceutics (Mol Pharm) Vol. 11 Issue 12 Pg. 4350-62 (Dec 01 2014) ISSN: 1543-8392 [Electronic] United States
• PMID: 25301142 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Drug Carriers
• Intercellular Adhesion Molecule-1

Topics

• Cell Line
• Drug Carriers (chemistry)
• Drug Delivery Systems (methods)
• Endothelial Cells (metabolism)
• Humans
• Intercellular Adhesion Molecule-1 (chemistry, metabolism)