Mechanism for IL-1 beta-mediated neovascularization unmasked by IL-1 beta knock-out mice.
We have reported that interleukin-1 beta (IL-1 beta) upregulates cardiac expression of vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2), raising the possibility that IL-1 beta plays an important role in VEGF-mediated neovascularization. In this study, we examined the cellular mechanism for ischemia-induced neovascularization using IL-1 beta knock-out (-/-) mice. Recovery of blood perfusion in ischemic hindlimb in IL-1 beta-/- mice was markedly (43% decrease) impaired as compared with the wild-type mice. CD31(+) vessel numbers and Ki-67(+) neo-capillaries were significantly (P < 0.01) decreased 44% and 68%, respectively. IL-1 beta expression was localized in the capillary vessels in ischemic limb muscles. Ischemia-induced expressions of hypoxia-inducible factor 1 alpha (HIF-1 alpha), VEGF, its receptor VEGFR-2 and vascular cell adhesion molecule-1 (VCAM-1) were markedly inhibited in the IL-1 beta-/- mice. Hindlimb ischemia-induced an increase (1.22% out of total nuclear cell) in CD34(-)/B220(-)/CD3(-)/Flk-1(+) hematopoietic stem cell population in peripheral blood in the wild-type mice, whereas in the IL-1 beta-/- mice such increase was only 0.09%. Injection of IL-1 beta protein into the wild-type mice markedly increased the ratio of the CD34(-)/B220(-)/CD3(-)/Flk-1(+) cell population (from 0.03% to 0.7%) in the peripheral blood associated with an increase in the number of endothelial cells. Such IL-1 beta-mediated increases in cell numbers were blocked by co-injection of anti-VEGF antibody. CD34(-)/B220(-)CD3(-)Flk-1(+) cells trans-differentiated into eNOS- and CD31-expressing endothelial cells in vivo and in vitro. This study demonstrates that IL-1 beta plays a key role in ischemia-induced neovascularization by mobilizing CD34(-)/B220(-)CD3(-)Flk-1(+) endothelial precursor cells in a VEGF-dependent manner as well as by upregulating expressions of VEGF, VEGFR-2 and adhesion molecules on endothelial cells.
Amano
Katsuya
K
Department of Medicine II and Cardiovascular Center, Kansai Medical University, 10-15 Fumizono-cho, Moriguchi, Osaka 570 8507, Japan.
Okigaki
Mitsuhiko
M
Adachi
Yasushi
Y
Fujiyama
Soichiro
S
Mori
Yasukio
Y
Kosaki
Atsushi
A
Iwasaka
Toshiji
T
Matsubara
Hiroaki
H
D000818:Animals; D018952:Antigens, CD34 / Q000096:biosynthesis; D015153:Blotting, Western; D017252:CD3 Complex / Q000096:biosynthesis; D002138:Calibration; D002454:Cell Differentiation; D002469:Cell Separation; D004730:Endothelium, Vascular / Q000378:metabolism; D005434:Flow Cytometry; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D007511:Ischemia; D019394:Ki-67 Antigen / Q000096:biosynthesis; D017078:Laser-Doppler Flowmetry; D017493:Leukocyte Common Antigens / Q000096:biosynthesis; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009389:Neovascularization, Pathologic; D010477:Perfusion; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis; D012313:RNA / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
D018952:Antigens, CD34; D017252:CD3 Complex; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007375:Interleukin-1; D019394:Ki-67 Antigen; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D014157:Transcription Factors; D019010:Vascular Cell Adhesion Molecule-1; D042461:Vascular Endothelial Growth Factor A; D012313:RNA; D040301:Vascular Endothelial Growth Factor Receptor-2; D017493:Leukocyte Common Antigens