Live dynamic imaging of caveolae pumping targeted antibody rapidly and specifically across endothelium in the lung.
How effectively and quickly endothelial caveolae can transcytose in vivo is unknown, yet critical for understanding their function and potential clinical utility. Here we use quantitative proteomics to identify aminopeptidase P (APP) concentrated in caveolae of lung endothelium. Electron microscopy confirms this and shows that APP antibody targets nanoparticles to caveolae. Dynamic intravital fluorescence microscopy reveals that targeted caveolae operate effectively as pumps, moving antibody within seconds from blood across endothelium into lung tissue, even against a concentration gradient. This active transcytosis requires normal caveolin-1 expression. Whole body gamma-scintigraphic imaging shows rapid, specific delivery into lung well beyond that achieved by standard vascular targeting. This caveolar trafficking in vivo may underscore a key physiological mechanism for selective transvascular exchange and may provide an enhanced delivery system for imaging agents, drugs, gene-therapy vectors and nanomedicines. 'In vivo proteomic imaging' as described here integrates organellar proteomics with multiple imaging techniques to identify an accessible target space that includes the transvascular pumping space of the caveola.
Oh
Phil
P
Sidney Kimmel Cancer Center, 10905 Road to the Cure, San Diego, California 92121, USA.
Borgström
Per
P
Witkiewicz
Halina
H
Li
Yan
Y
Borgström
Bengt J
BJ
Chrastina
Adrian
A
Iwata
Koji
K
Zinn
Kurt R
KR
Baldwin
Richard
R
Testa
Jacqueline E
JE
Schnitzer
Jan E
JE
D000626:Aminopeptidases / Q000276:immunology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000493:pharmacokinetics*; D021941:Caveolae / Q000276:immunology* / Q000502:physiology; D051242:Caveolin 1 / Q000378:metabolism; D004337:Drug Carriers; D016503:Drug Delivery Systems; D004705:Endocytosis; D004730:Endothelium, Vascular / Q000276:immunology* / Q000502:physiology; D008168:Lung / Q000098:blood supply / Q000276:immunology* / Q000502:physiology; D051379:Mice; D053758:Nanoparticles; D040901:Proteomics / Q000379:methods; D011877:Radionuclide Imaging; D051381:Rats; D015899:Tomography, Emission-Computed, Single-Photon; D014741:Video Recording
D000911:Antibodies, Monoclonal; D051242:Caveolin 1; D004337:Drug Carriers; D000626:Aminopeptidases; C022750:X-Pro aminopeptidase