TY - JOUR
T1 - Targeting of 12/15-Lipoxygenase in retinal endothelial cells, but not in monocytes/macrophages, attenuates high glucose-induced retinal leukostasis
AU - Ibrahim, Ahmed S.
AU - Saleh, Heba
AU - El-Shafey, Mohamed
AU - Hussein, Khaled A.
AU - El-Masry, Khaled
AU - Baban, Babak
AU - Sheibani, Nader
AU - Wang, Mong Heng
AU - Tawfik, Amany
AU - Al-Shabrawey, Mohamed
N1 - Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017/6/1
Y1 - 2017/6/1
N2 - Aims Our previous studies have established a role for 12/15-lipoxygenase (LO) in mediating the inflammatory response in diabetic retinopathy (DR). However, the extent at which the local or systemic induction of 12/15-LO activity involved is unclear. Thus, the current study aimed to characterize the relative contribution of retinal endothelial versus monocytic/macrophagic 12/15-LO to inflammatory responses in DR. Materials & methods We first generated a clustered heat map for circulating bioactive lipid metabolites in the plasma of streptozotocin (STZ)-induced diabetic mice using liquid chromatography coupled with mass-spectrometry (LC–MS) to evaluate changes in circulating 12/15-LO activity. This was followed by comparing the in vitro mouse endothelium-leukocytes interaction between leukocytes isolated from 12/15-LO knockout (KO) versus those isolated from wild type (WT) mice using the myeloperoxidase (MPO) assay. Finally, we examined the effects of knocking down or inhibiting endothelial 12/15-LO on diabetes-induced endothelial cell activation and ICAM-1 expression. Results Analysis of plasma bioactive lipids' heat map revealed that the activity of circulating 12/15-LO was not altered by diabetes as evident by no significant changes in the plasma levels of major metabolites derived from 12/15-lipoxygenation of different PUFAs, including linoleic acid (13-HODE), arachidonic acid (12- and 15- HETEs), eicosapentaenoic acid (12- and 15- HEPEs), or docosahexaenoic acid (17-HDoHE). Moreover, leukocytes from 12/15-LO KO mice displayed a similar increase in adhesion to high glucose (HG)-activated endothelial cells as do leukocytes from WT mice. Furthermore, abundant proteins of 12-LO and 15-LO were detected in human retinal endothelial cells (HRECs), while it was undetected (15-LO) or hardly detectable (12-LO) in human monocyte-like U937 cells. Inhibition or knock down of endothelial 12/15-LO in HRECs blocked HG-induced expression of ICAM-1, a well-known identified important molecule for leukocyte adhesion in DR. Conclusion Our data support that endothelial, rather than monocytic/macrophagic, 12/15-LO has a critical role in hyperglycemia-induced ICAM-1 expression, leukocyte adhesion, and subsequent local retinal barrier dysfunction. This may facilitate the development of more precisely targeted treatment strategies for DR.
AB - Aims Our previous studies have established a role for 12/15-lipoxygenase (LO) in mediating the inflammatory response in diabetic retinopathy (DR). However, the extent at which the local or systemic induction of 12/15-LO activity involved is unclear. Thus, the current study aimed to characterize the relative contribution of retinal endothelial versus monocytic/macrophagic 12/15-LO to inflammatory responses in DR. Materials & methods We first generated a clustered heat map for circulating bioactive lipid metabolites in the plasma of streptozotocin (STZ)-induced diabetic mice using liquid chromatography coupled with mass-spectrometry (LC–MS) to evaluate changes in circulating 12/15-LO activity. This was followed by comparing the in vitro mouse endothelium-leukocytes interaction between leukocytes isolated from 12/15-LO knockout (KO) versus those isolated from wild type (WT) mice using the myeloperoxidase (MPO) assay. Finally, we examined the effects of knocking down or inhibiting endothelial 12/15-LO on diabetes-induced endothelial cell activation and ICAM-1 expression. Results Analysis of plasma bioactive lipids' heat map revealed that the activity of circulating 12/15-LO was not altered by diabetes as evident by no significant changes in the plasma levels of major metabolites derived from 12/15-lipoxygenation of different PUFAs, including linoleic acid (13-HODE), arachidonic acid (12- and 15- HETEs), eicosapentaenoic acid (12- and 15- HEPEs), or docosahexaenoic acid (17-HDoHE). Moreover, leukocytes from 12/15-LO KO mice displayed a similar increase in adhesion to high glucose (HG)-activated endothelial cells as do leukocytes from WT mice. Furthermore, abundant proteins of 12-LO and 15-LO were detected in human retinal endothelial cells (HRECs), while it was undetected (15-LO) or hardly detectable (12-LO) in human monocyte-like U937 cells. Inhibition or knock down of endothelial 12/15-LO in HRECs blocked HG-induced expression of ICAM-1, a well-known identified important molecule for leukocyte adhesion in DR. Conclusion Our data support that endothelial, rather than monocytic/macrophagic, 12/15-LO has a critical role in hyperglycemia-induced ICAM-1 expression, leukocyte adhesion, and subsequent local retinal barrier dysfunction. This may facilitate the development of more precisely targeted treatment strategies for DR.
KW - 12-HETE
KW - 12/15-Lipoxygenase
KW - 15-HETE
KW - Bioactive lipids
KW - Blood retinal barrier
KW - Diabetic retinopathy
KW - Eicosanoids
KW - ICAM-1
KW - Leukostasis
KW - Permeability
UR - http://www.scopus.com/inward/record.url?scp=85017318954&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85017318954&partnerID=8YFLogxK
U2 - 10.1016/j.bbalip.2017.03.010
DO - 10.1016/j.bbalip.2017.03.010
M3 - Article
C2 - 28351645
AN - SCOPUS:85017318954
SN - 1388-1981
VL - 1862
SP - 636
EP - 645
JO - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
JF - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
IS - 6
ER -