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 prevents retinal capillary degeneration during diabetes. The retinal vasculature was visualized in flat mounts using concomitant labeling of endothelium (isolectin) and basement membrane (collagen IV). Acellular capillaries can be visualized by continuance of collagen IV positivity but loss of endothelium. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic. A: Graph showing the number of acellular capillaries in retina in the peripheral and central retina. Diabetic rats with scrambled pHBSP displayed more acellular capillaries than control rats, which received the scrambled pHBSP (*P < 0.05). The pHBSP peptide significantly reduced the number of the acellular capillaries to normal levels in the inner retina (+P < 0.05). Data are mean ± SEM; n = 6 per group. B and C: Images showing acellular capillaries (arrows) in the diabetic animals that received the scrambled peptide. Acellular capillaries are observed when vessels are collagen IV positive (red) and negative for lectin (green). There are more acellular vessel profiles present in the diabetic retina that received the scramble peptide relative to the diabetic animals that received the pHBSP peptide. Sc’pHBSP, scrambled pHBSP. (A high-quality digital 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 6: pHBSP prevents retinal capillary degeneration during diabetes. The retinal vasculature was visualized in flat mounts using concomitant labeling of endothelium (isolectin) and basement membrane (collagen IV). Acellular capillaries can be visualized by continuance of collagen IV positivity but loss of endothelium. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic. A: Graph showing the number of acellular capillaries in retina in the peripheral and central retina. Diabetic rats with scrambled pHBSP displayed more acellular capillaries than control rats, which received the scrambled pHBSP (*P < 0.05). The pHBSP peptide significantly reduced the number of the acellular capillaries to normal levels in the inner retina (+P < 0.05). Data are mean ± SEM; n = 6 per group. B and C: Images showing acellular capillaries (arrows) in the diabetic animals that received the scrambled peptide. Acellular capillaries are observed when vessels are collagen IV positive (red) and negative for lectin (green). There are more acellular vessel profiles present in the diabetic retina that received the scramble peptide relative to the diabetic animals that received the pHBSP peptide. Sc’pHBSP, scrambled pHBSP. (A high-quality digital representation of this figure is available in the online issue.)

Mentions: As diabetes progresses, the death of retinal pericytes and endothelium results in acellular capillary formation, a lesion that takes ∼5–6 months to become obvious in diabetic rats (30). While various approaches have been used to visualize acellular capillaries, we used the fact that such naked basement membrane tubes remain positive for collagen IV and negative for isolectin and can be quantified using confocal microscopy (Fig. 6A). The diabetic retina contained approximately fourfold increased numbers of acellular capillaries when compared with nondiabetic control retina (P < 0.05) (Fig. 6A and B). pHBSP treatment for 1 month, after 6 previous months of diabetes, significantly reduced acellular capillaries in the retina, and there were no differences between these treated patients with diabetes in comparison with nondiabetic control groups (Fig. 6B).


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 prevents retinal capillary degeneration during diabetes. The retinal vasculature was visualized in flat mounts using concomitant labeling of endothelium (isolectin) and basement membrane (collagen IV). Acellular capillaries can be visualized by continuance of collagen IV positivity but loss of endothelium. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic. A: Graph showing the number of acellular capillaries in retina in the peripheral and central retina. Diabetic rats with scrambled pHBSP displayed more acellular capillaries than control rats, which received the scrambled pHBSP (*P < 0.05). The pHBSP peptide significantly reduced the number of the acellular capillaries to normal levels in the inner retina (+P < 0.05). Data are mean ± SEM; n = 6 per group. B and C: Images showing acellular capillaries (arrows) in the diabetic animals that received the scrambled peptide. Acellular capillaries are observed when vessels are collagen IV positive (red) and negative for lectin (green). There are more acellular vessel profiles present in the diabetic retina that received the scramble peptide relative to the diabetic animals that received the pHBSP peptide. Sc’pHBSP, scrambled pHBSP. (A high-quality digital 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 6: pHBSP prevents retinal capillary degeneration during diabetes. The retinal vasculature was visualized in flat mounts using concomitant labeling of endothelium (isolectin) and basement membrane (collagen IV). Acellular capillaries can be visualized by continuance of collagen IV positivity but loss of endothelium. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic. A: Graph showing the number of acellular capillaries in retina in the peripheral and central retina. Diabetic rats with scrambled pHBSP displayed more acellular capillaries than control rats, which received the scrambled pHBSP (*P < 0.05). The pHBSP peptide significantly reduced the number of the acellular capillaries to normal levels in the inner retina (+P < 0.05). Data are mean ± SEM; n = 6 per group. B and C: Images showing acellular capillaries (arrows) in the diabetic animals that received the scrambled peptide. Acellular capillaries are observed when vessels are collagen IV positive (red) and negative for lectin (green). There are more acellular vessel profiles present in the diabetic retina that received the scramble peptide relative to the diabetic animals that received the pHBSP peptide. Sc’pHBSP, scrambled pHBSP. (A high-quality digital representation of this figure is available in the online issue.)
Mentions: As diabetes progresses, the death of retinal pericytes and endothelium results in acellular capillary formation, a lesion that takes ∼5–6 months to become obvious in diabetic rats (30). While various approaches have been used to visualize acellular capillaries, we used the fact that such naked basement membrane tubes remain positive for collagen IV and negative for isolectin and can be quantified using confocal microscopy (Fig. 6A). The diabetic retina contained approximately fourfold increased numbers of acellular capillaries when compared with nondiabetic control retina (P < 0.05) (Fig. 6A and B). pHBSP treatment for 1 month, after 6 previous months of diabetes, significantly reduced acellular capillaries in the retina, and there were no differences between these treated patients with diabetes in comparison with nondiabetic control groups (Fig. 6B).

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