Neuropilin-VEGF signaling pathway acts as a key modulator of vascular, lymphatic, and inflammatory cell responses of the bladder to intravesical BCG treatment.
Recent findings indicate that VEGF receptors and coreceptors (neuropilins; NRP) are expressed on nonendothelial cells in human bladder urothelium, in one human bladder cancer cell line (J82), and in the mouse bladder urothelium. In addition, VEGFR1, VEGFR2, NRP1, and NRP2 expressions were upregulated in animal models of chronic bladder inflammation induced by four weekly instillations of protease-activated receptors (PAR)-activating peptides or bacillus Calmette-Guérin (BCG) into the mouse bladder. Here, we used four weekly instillations of BCG as a model for chronic bladder inflammation to further investigate whether VEGF receptors and NRPs play a role in the migration of inflammatory cells and inflammation-induced lymphangiogenesis and angiogenesis. For this purpose, we used neutralizing antibodies that were engineered to specifically block the binding of VEGF to NRP (anti-NRP1(B)) and the binding of semaphorins to NRP (anti-NRP1(A)). C57BL/6 mice received intraperitoneal injections of PBS, anti-NRP1(A)- or anti-NRP1(B)-neutralizing antibodies and then were challenged chronically with intravesical PBS or BCG. At the end of chronic challenge period, a fluorescent internalizable tracer, scVEGF/Cy5.5, was administered to all mice and near-infrared fluorescence images were obtained in vivo and in real time. BCG increased the overall accumulation of scVEGF/Cy5.5 in the urinary bladder urothelium and inflammatory cells. In addition, BCG increased the density of blood and lymphatic vessels concomitantly with an upregulation of NRP2 expression in lymphatic vessels. Treatment of the mice with NRP1-neutralizing antibodies dramatically reduced scVEGF/Cy5.5 uptake, polymorphonuclear (myeloperoxidase-positive cells) and dendritic cell (CD11c-positive cells) infiltration, and decreased the overall density of BCG-induced blood and lymphatic vessels. These results implicate NRPs as critical in vivo regulators of the vascular and inflammatory responses to the intravesical administration of BCG.
Saban
Marcia R
MR
Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA. ricardo-saban@ouhsc.edu
Sferra
Thomas J
TJ
Davis
Carole A
CA
Simpson
Cindy
C
Allen
Arielle
A
Maier
Julie
J
Fowler
Ben
B
Knowlton
Nicholas
N
Birder
Lori
L
Wu
Xue-Ru
XR
Saban
Ricardo
R
D000818:Animals; D001500:BCG Vaccine; D002465:Cell Movement / Q000276:immunology; D003556:Cystitis / Q000139:chemically induced / Q000503:physiopathology*; D005260:Female; D006801:Humans; D042583:Lymphangiogenesis / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000503:physiopathology; D039942:Neuropilin-1 / Q000276:immunology / Q000502:physiology*; D039921:Neuropilins / Q000502:physiology*; D040262:Receptors, Vascular Endothelial Growth Factor / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D001743:Urinary Bladder / Q000098:blood supply / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
D001500:BCG Vaccine; D039921:Neuropilins; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D039942:Neuropilin-1; D040262:Receptors, Vascular Endothelial Growth Factor