RESUMO
OBJECTIVE: Ischemia caused by narrowing of femoral artery is a major cause of peripheral arterial disease and morbidity affecting patients with diabetes mellitus. We have previously reported that the inhibition of the angiogenic response to VEGF (vascular endothelial growth factor) in diabetic mice was associated with the increased expression of SHP-1 (SH2 domain-containing phosphatase 1), a protein that can be activated by the AT2 (angiotensin II type 2) receptor. Deletion of AT2 receptor has been shown to promote angiogenesis within the ischemic muscle. However, the relative impact of AT2 receptor in diabetic condition remains unknown. APPROACH AND RESULTS: Nondiabetic and diabetic AT2 null (Atgr2-/Y) mice underwent femoral artery ligation after 2 months of diabetes mellitus. Blood perfusion was measured every week ≤4 weeks post-surgery. Expression of the VEGF, SHP-1, and renin-angiotensin pathways was evaluated. Blood flow in the ischemic muscle of diabetic Atgr2-/Y mice recovered faster and ≤80% after 4 weeks compared with 51% recovery in diabetic control littermates. Diabetic Atgr2-/Y had reduced apoptotic endothelial cells and elevated small vessel formation compared with diabetic Atgr2+/Y mice, as well as increased SHP-1 expression and reduced VEGF receptor activity. In endothelial cells, high glucose levels and AT2 agonist treatment did not change SHP-1, VEGF, and VEGF receptor expression. However, the activity of SHP-1 and its association with the VEGF receptors were increased, causing inhibition of the VEGF action in endothelial cell proliferation and migration. CONCLUSIONS: Our results suggest that the deletion of AT2 receptor reduced SHP-1 activity and restored VEGF actions, leading to an increased blood flow reperfusion after ischemia in diabetes mellitus.
Assuntos
Diabetes Mellitus/metabolismo , Angiopatias Diabéticas/metabolismo , Isquemia/metabolismo , Músculo Esquelético/irrigação sanguínea , Neovascularização Fisiológica , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo , Receptor Tipo 2 de Angiotensina/deficiência , Fator A de Crescimento do Endotélio Vascular/metabolismo , Animais , Glicemia/metabolismo , Bovinos , Movimento Celular , Proliferação de Células , Células Cultivadas , Diabetes Mellitus/genética , Diabetes Mellitus/fisiopatologia , Angiopatias Diabéticas/genética , Angiopatias Diabéticas/fisiopatologia , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Deleção de Genes , Genótipo , Membro Posterior , Isquemia/genética , Isquemia/fisiopatologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenótipo , Receptor Tipo 2 de Angiotensina/genética , Receptores de Fatores de Crescimento do Endotélio Vascular/metabolismo , Recuperação de Função Fisiológica , Fluxo Sanguíneo Regional , Sistema Renina-Angiotensina , Transdução de Sinais , Fatores de TempoRESUMO
Peripheral artery disease is a severe complication of diabetes. We have reported that the deletion of angiotensin type 2 receptor in diabetic mice promoted vascular angiogenesis in the ischaemic muscle 4 weeks following ischaemia. However, the angiotensin type 2 receptor deletion beneficial effects occurred 2 weeks post surgery suggesting that angiotensin type 2 receptor may regulate other pro-angiogenic signalling pathways during the early phases of ischaemia. Nondiabetic and diabetic angiotensin type 2 receptor-deficient mice (Agtr2-/Y) underwent femoral artery ligation after 2 months of diabetes. Blood perfusion was measured every week up to 2 weeks post surgery. Expression of vascular endothelial growth factor, vascular endothelial growth factor receptor and endothelial nitric oxide synthase expression and activity were evaluated. Blood flow reperfusion in the ischaemic muscle of diabetic Agtr2+/Y mice was recovered at 35% as compared to a 68% recovery in diabetic Agtr2-/Y mice. The expression of vascular endothelial growth factor and its receptors was diminished in diabetic Agtr2+/Y mice, an observation not seen in diabetic Agtr2-/Y mice. Interestingly, Agtr2-/Y mice were protected from diabetes-induced glutathionylation, nitration and decreased endothelial nitric oxide synthase expression, which correlated with reduced endothelial cell death and enhanced vascular density in diabetic ischaemic muscle. In conclusion, our results suggest that the deletion of angiotensin type 2 receptor promotes blood flow reperfusion in diabetes by favouring endothelial cell survival and function.
Assuntos
Diabetes Mellitus/enzimologia , Células Endoteliais/enzimologia , Glutationa/metabolismo , Isquemia/enzimologia , Músculo Esquelético/irrigação sanguínea , Neovascularização Fisiológica , Nitratos/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Doença Arterial Periférica/enzimologia , Receptor Tipo 2 de Angiotensina/deficiência , Animais , Apoptose , Velocidade do Fluxo Sanguíneo , Bovinos , Células Cultivadas , Diabetes Mellitus/genética , Modelos Animais de Doenças , Células Endoteliais/patologia , Membro Posterior , Isquemia/genética , Isquemia/fisiopatologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Doença Arterial Periférica/genética , Doença Arterial Periférica/fisiopatologia , Processamento de Proteína Pós-Traducional , Receptor Tipo 2 de Angiotensina/genética , Recuperação de Função Fisiológica , Fluxo Sanguíneo RegionalRESUMO
Since its first description in 1982, the zoonotic life-threatening Shiga toxin-producing Escherichia coli O157:H7 has emerged as an important food- and water-borne pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic-uremic syndrome in humans. In the last decade, increases in E. coli O157:H7 outbreaks were associated with environmental contamination in water and through fresh produce such as green leaves or vegetables. Both intrinsic (genetic adaptation) and extrinsic factors may contribute and help E. coli O157:H7 to survive in adverse environments. This makes it even more difficult to detect and monitor food and water safety for public health surveillance. E. coli O157:H7 has evolved in behaviors and strategies to persist in the environment.