Limits...
Intervention with an erythropoietin-derived peptide protects against neuroglial and vascular degeneration during diabetic retinopathy.

McVicar CM, Hamilton R, Colhoun LM, Gardiner TA, Brines M, Cerami A, Stitt AW - Diabetes (2011)

Bottom Line: In the diabetic retina, Müller glial expression of glial fibrillary acidic protein was increased when compared with nondiabetic controls, but pHBSP significantly reduced this stress-related response (P < 0.001).CD11b+ microglia and proinflammatory cytokines were elevated in diabetic retina responses, and some of these responses were attenuated by pHBSP (P < 0.01-0.001). pHBSP significantly reduced diabetes-linked DNA damage as determined by 8-hydroxydeoxyguanosine and transferase-mediated dUTP nick-end labeling positivity and also prevented acellular capillary formation (P < 0.05).In OIR, pHBSP had no effect on preretinal neovascularization at any dose.

View Article: PubMed Central - PubMed

Affiliation: Centre for Vision and Vascular Science, Queen’s University Belfast, Belfast, Northern Ireland, UK.

ABSTRACT

Objective: Erythropoietin (EPO) may be protective for early stage diabetic retinopathy, although there are concerns that it could exacerbate retinal angiogenesis and thrombosis. A peptide based on the EPO helix-B domain (helix B-surface peptide [pHBSP]) is nonerythrogenic but retains tissue-protective properties, and this study evaluates its therapeutic potential in diabetic retinopathy.

Research design and methods: After 6 months of streptozotocin-induced diabetes, rats (n = 12) and age-matched nondiabetic controls (n = 12) were evenly split into pHBSP and scrambled peptide groups and injected daily (10 μg/kg per day) for 1 month. The retina was investigated for glial dysfunction, microglial activation, and neuronal DNA damage. The vasculature was dual stained with isolectin and collagen IV. Retinal cytokine expression was quantified using real-time RT-PCR. In parallel, oxygen-induced retinopathy (OIR) was used to evaluate the effects of pHBSP on retinal ischemia and neovascularization (1-30 μg/kg pHBSP or control peptide).

Results: pHBSP or scrambled peptide treatment did not alter hematocrit. In the diabetic retina, Müller glial expression of glial fibrillary acidic protein was increased when compared with nondiabetic controls, but pHBSP significantly reduced this stress-related response (P < 0.001). CD11b+ microglia and proinflammatory cytokines were elevated in diabetic retina responses, and some of these responses were attenuated by pHBSP (P < 0.01-0.001). pHBSP significantly reduced diabetes-linked DNA damage as determined by 8-hydroxydeoxyguanosine and transferase-mediated dUTP nick-end labeling positivity and also prevented acellular capillary formation (P < 0.05). In OIR, pHBSP had no effect on preretinal neovascularization at any dose.

Conclusions: Treatment with an EPO-derived peptide after diabetes is fully established can significantly protect against neuroglial and vascular degenerative pathology without altering hematocrit or exacerbating neovascularization. These findings have therapeutic implications for disorders such as diabetic retinopathy.

Show MeSH

Related in: MedlinePlus

pHBSP decreases ischemia at 1 μg/kg and exacerbates preretinal neovascularization in OIR. The murine retinal vasculature was assessed in flat mounts after OIR using isolectin labeling and confocal microscopy. A: Retinal ischemia: pHBSP at 1 μg/kg decreases the ischemic region (***P < 0.001), while the higher doses of 10 and 30 μg/kg have no effect on ischemia. B: Retinal neovascularization: upon quantification of preretinal vessels, pHBSP had no significant effect on neovascularization at any of the doses tested (1, 10, and 30 μg/kg) when compared with the scrambled peptide or PBS control. Data are mean ± SEM; n = 6 per group. PBS, PBS control; Sc, scrambled pHBSP. C and D: Retinal flat mounts showing hyperfluorescent preretinal neovascularization in PBS-treated (C) and 1 μg/kg of pHBSP-treated (D) OIR mice (arrow). (A high-quality color representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3198080&req=5

Figure 7: pHBSP decreases ischemia at 1 μg/kg and exacerbates preretinal neovascularization in OIR. The murine retinal vasculature was assessed in flat mounts after OIR using isolectin labeling and confocal microscopy. A: Retinal ischemia: pHBSP at 1 μg/kg decreases the ischemic region (***P < 0.001), while the higher doses of 10 and 30 μg/kg have no effect on ischemia. B: Retinal neovascularization: upon quantification of preretinal vessels, pHBSP had no significant effect on neovascularization at any of the doses tested (1, 10, and 30 μg/kg) when compared with the scrambled peptide or PBS control. Data are mean ± SEM; n = 6 per group. PBS, PBS control; Sc, scrambled pHBSP. C and D: Retinal flat mounts showing hyperfluorescent preretinal neovascularization in PBS-treated (C) and 1 μg/kg of pHBSP-treated (D) OIR mice (arrow). (A high-quality color representation of this figure is available in the online issue.)

Mentions: As determined in the murine OIR model, pHBSP did not increase the percentage of reticulocytes in peripheral blood over an acute time frame (Supplementary Fig. 5). A dose of 1 μg/kg of pHBSP resulted in a decrease in the ischemic region of the retina. The higher doses of the peptide returned the ischemic region to normal (Fig. 7A). Consistent with the well-characterized OIR response, hyperoxia induced a temporal pattern of central retina vascular insufficiency upon return to room air at P12, which led to a reproducible preretinal neovascularization observable on flat mounts (Fig. 7B). Over a dose response range, pHBSP administered from P12 to P16 inclusive demonstrated no significant increase in ischemia-driven preretinal neovascularization (Fig. 7B–D).


Intervention with an erythropoietin-derived peptide protects against neuroglial and vascular degeneration during diabetic retinopathy.

McVicar CM, Hamilton R, Colhoun LM, Gardiner TA, Brines M, Cerami A, Stitt AW - Diabetes (2011)

pHBSP decreases ischemia at 1 μg/kg and exacerbates preretinal neovascularization in OIR. The murine retinal vasculature was assessed in flat mounts after OIR using isolectin labeling and confocal microscopy. A: Retinal ischemia: pHBSP at 1 μg/kg decreases the ischemic region (***P < 0.001), while the higher doses of 10 and 30 μg/kg have no effect on ischemia. B: Retinal neovascularization: upon quantification of preretinal vessels, pHBSP had no significant effect on neovascularization at any of the doses tested (1, 10, and 30 μg/kg) when compared with the scrambled peptide or PBS control. Data are mean ± SEM; n = 6 per group. PBS, PBS control; Sc, scrambled pHBSP. C and D: Retinal flat mounts showing hyperfluorescent preretinal neovascularization in PBS-treated (C) and 1 μg/kg of pHBSP-treated (D) OIR mice (arrow). (A high-quality color representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198080&req=5

Figure 7: pHBSP decreases ischemia at 1 μg/kg and exacerbates preretinal neovascularization in OIR. The murine retinal vasculature was assessed in flat mounts after OIR using isolectin labeling and confocal microscopy. A: Retinal ischemia: pHBSP at 1 μg/kg decreases the ischemic region (***P < 0.001), while the higher doses of 10 and 30 μg/kg have no effect on ischemia. B: Retinal neovascularization: upon quantification of preretinal vessels, pHBSP had no significant effect on neovascularization at any of the doses tested (1, 10, and 30 μg/kg) when compared with the scrambled peptide or PBS control. Data are mean ± SEM; n = 6 per group. PBS, PBS control; Sc, scrambled pHBSP. C and D: Retinal flat mounts showing hyperfluorescent preretinal neovascularization in PBS-treated (C) and 1 μg/kg of pHBSP-treated (D) OIR mice (arrow). (A high-quality color representation of this figure is available in the online issue.)
Mentions: As determined in the murine OIR model, pHBSP did not increase the percentage of reticulocytes in peripheral blood over an acute time frame (Supplementary Fig. 5). A dose of 1 μg/kg of pHBSP resulted in a decrease in the ischemic region of the retina. The higher doses of the peptide returned the ischemic region to normal (Fig. 7A). Consistent with the well-characterized OIR response, hyperoxia induced a temporal pattern of central retina vascular insufficiency upon return to room air at P12, which led to a reproducible preretinal neovascularization observable on flat mounts (Fig. 7B). Over a dose response range, pHBSP administered from P12 to P16 inclusive demonstrated no significant increase in ischemia-driven preretinal neovascularization (Fig. 7B–D).

Bottom Line: In the diabetic retina, Müller glial expression of glial fibrillary acidic protein was increased when compared with nondiabetic controls, but pHBSP significantly reduced this stress-related response (P < 0.001).CD11b+ microglia and proinflammatory cytokines were elevated in diabetic retina responses, and some of these responses were attenuated by pHBSP (P < 0.01-0.001). pHBSP significantly reduced diabetes-linked DNA damage as determined by 8-hydroxydeoxyguanosine and transferase-mediated dUTP nick-end labeling positivity and also prevented acellular capillary formation (P < 0.05).In OIR, pHBSP had no effect on preretinal neovascularization at any dose.

View Article: PubMed Central - PubMed

Affiliation: Centre for Vision and Vascular Science, Queen’s University Belfast, Belfast, Northern Ireland, UK.

ABSTRACT

Objective: Erythropoietin (EPO) may be protective for early stage diabetic retinopathy, although there are concerns that it could exacerbate retinal angiogenesis and thrombosis. A peptide based on the EPO helix-B domain (helix B-surface peptide [pHBSP]) is nonerythrogenic but retains tissue-protective properties, and this study evaluates its therapeutic potential in diabetic retinopathy.

Research design and methods: After 6 months of streptozotocin-induced diabetes, rats (n = 12) and age-matched nondiabetic controls (n = 12) were evenly split into pHBSP and scrambled peptide groups and injected daily (10 μg/kg per day) for 1 month. The retina was investigated for glial dysfunction, microglial activation, and neuronal DNA damage. The vasculature was dual stained with isolectin and collagen IV. Retinal cytokine expression was quantified using real-time RT-PCR. In parallel, oxygen-induced retinopathy (OIR) was used to evaluate the effects of pHBSP on retinal ischemia and neovascularization (1-30 μg/kg pHBSP or control peptide).

Results: pHBSP or scrambled peptide treatment did not alter hematocrit. In the diabetic retina, Müller glial expression of glial fibrillary acidic protein was increased when compared with nondiabetic controls, but pHBSP significantly reduced this stress-related response (P < 0.001). CD11b+ microglia and proinflammatory cytokines were elevated in diabetic retina responses, and some of these responses were attenuated by pHBSP (P < 0.01-0.001). pHBSP significantly reduced diabetes-linked DNA damage as determined by 8-hydroxydeoxyguanosine and transferase-mediated dUTP nick-end labeling positivity and also prevented acellular capillary formation (P < 0.05). In OIR, pHBSP had no effect on preretinal neovascularization at any dose.

Conclusions: Treatment with an EPO-derived peptide after diabetes is fully established can significantly protect against neuroglial and vascular degenerative pathology without altering hematocrit or exacerbating neovascularization. These findings have therapeutic implications for disorders such as diabetic retinopathy.

Show MeSH
Related in: MedlinePlus