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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.

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Cytokine expression in the diabetic retina is regulated by pHBSP A: IL-10 was decreased in the diabetic rat with scrambled pHBSP relative to the control with scrambled pHBSP (***P < 0.001). The level of IL-10, the anti-inflammatory cytokine, was elevated again with pHBSP in the diabetic rat when compared with the scrambled pHBSP (+P < 0.05). B: TNF-α was increased in the diabetic rat, which received 10 μg/kg of scrambled pHBSP, relative to the control, which received the scrambled pHBSP (***P < 0.001). This elevated level in the diabetic rat was significantly decreased with the active pHBSP (+++P < 0.001). C: IL-6 was increased in the diabetic rat, which received 10 μg/kg of scrambled pHBSP, relative to the control, which received the scrambled pHBSP (***P < 0.001). This elevated level in the diabetic rat was significantly decreased with the active pHBSP (+++P < 0.001). D: STZ-induced diabetes caused a reduction in IL-1β levels when compared with control tissue treated with scrambled peptide (***P < 0.001). Treatment with pHBSP caused a reduction in IL-1β levels both in nondiabetic tissue and diabetic tissue (***P < 0.001; +++P < 0.001). The number of animals in each group was six. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic.
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Figure 5: Cytokine expression in the diabetic retina is regulated by pHBSP A: IL-10 was decreased in the diabetic rat with scrambled pHBSP relative to the control with scrambled pHBSP (***P < 0.001). The level of IL-10, the anti-inflammatory cytokine, was elevated again with pHBSP in the diabetic rat when compared with the scrambled pHBSP (+P < 0.05). B: TNF-α was increased in the diabetic rat, which received 10 μg/kg of scrambled pHBSP, relative to the control, which received the scrambled pHBSP (***P < 0.001). This elevated level in the diabetic rat was significantly decreased with the active pHBSP (+++P < 0.001). C: IL-6 was increased in the diabetic rat, which received 10 μg/kg of scrambled pHBSP, relative to the control, which received the scrambled pHBSP (***P < 0.001). This elevated level in the diabetic rat was significantly decreased with the active pHBSP (+++P < 0.001). D: STZ-induced diabetes caused a reduction in IL-1β levels when compared with control tissue treated with scrambled peptide (***P < 0.001). Treatment with pHBSP caused a reduction in IL-1β levels both in nondiabetic tissue and diabetic tissue (***P < 0.001; +++P < 0.001). The number of animals in each group was six. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic.

Mentions: In keeping with the pattern observed with the resident immune cells within the retina, transcripts for the anti-inflammatory cytokine IL-10 were significantly decreased in the diabetic rat retina relative to age-matched controls (P < 0.001), and pHBSP treatment returned these expression levels close to levels seen in controls (Fig. 5A). By contrast, mRNAs for the proinflammatory cytokines TNF-α and IL-6 were significantly elevated in diabetic retina (P < 0.001), and pHBSP prevented this increase and restored expression to normal levels in both cases (Fig. 5B and C). STZ-induced diabetes caused a reduction in IL-1β levels when compared with control tissue treated with scrambled peptide (P < 0.001). Treatment with pHBSP caused a reduction in IL-1β levels both in nondiabetic tissue and diabetic tissue (P < 0.001) (Fig. 5D).


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)

Cytokine expression in the diabetic retina is regulated by pHBSP A: IL-10 was decreased in the diabetic rat with scrambled pHBSP relative to the control with scrambled pHBSP (***P < 0.001). The level of IL-10, the anti-inflammatory cytokine, was elevated again with pHBSP in the diabetic rat when compared with the scrambled pHBSP (+P < 0.05). B: TNF-α was increased in the diabetic rat, which received 10 μg/kg of scrambled pHBSP, relative to the control, which received the scrambled pHBSP (***P < 0.001). This elevated level in the diabetic rat was significantly decreased with the active pHBSP (+++P < 0.001). C: IL-6 was increased in the diabetic rat, which received 10 μg/kg of scrambled pHBSP, relative to the control, which received the scrambled pHBSP (***P < 0.001). This elevated level in the diabetic rat was significantly decreased with the active pHBSP (+++P < 0.001). D: STZ-induced diabetes caused a reduction in IL-1β levels when compared with control tissue treated with scrambled peptide (***P < 0.001). Treatment with pHBSP caused a reduction in IL-1β levels both in nondiabetic tissue and diabetic tissue (***P < 0.001; +++P < 0.001). The number of animals in each group was six. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic.
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Figure 5: Cytokine expression in the diabetic retina is regulated by pHBSP A: IL-10 was decreased in the diabetic rat with scrambled pHBSP relative to the control with scrambled pHBSP (***P < 0.001). The level of IL-10, the anti-inflammatory cytokine, was elevated again with pHBSP in the diabetic rat when compared with the scrambled pHBSP (+P < 0.05). B: TNF-α was increased in the diabetic rat, which received 10 μg/kg of scrambled pHBSP, relative to the control, which received the scrambled pHBSP (***P < 0.001). This elevated level in the diabetic rat was significantly decreased with the active pHBSP (+++P < 0.001). C: IL-6 was increased in the diabetic rat, which received 10 μg/kg of scrambled pHBSP, relative to the control, which received the scrambled pHBSP (***P < 0.001). This elevated level in the diabetic rat was significantly decreased with the active pHBSP (+++P < 0.001). D: STZ-induced diabetes caused a reduction in IL-1β levels when compared with control tissue treated with scrambled peptide (***P < 0.001). Treatment with pHBSP caused a reduction in IL-1β levels both in nondiabetic tissue and diabetic tissue (***P < 0.001; +++P < 0.001). The number of animals in each group was six. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic.
Mentions: In keeping with the pattern observed with the resident immune cells within the retina, transcripts for the anti-inflammatory cytokine IL-10 were significantly decreased in the diabetic rat retina relative to age-matched controls (P < 0.001), and pHBSP treatment returned these expression levels close to levels seen in controls (Fig. 5A). By contrast, mRNAs for the proinflammatory cytokines TNF-α and IL-6 were significantly elevated in diabetic retina (P < 0.001), and pHBSP prevented this increase and restored expression to normal levels in both cases (Fig. 5B and C). STZ-induced diabetes caused a reduction in IL-1β levels when compared with control tissue treated with scrambled peptide (P < 0.001). Treatment with pHBSP caused a reduction in IL-1β levels both in nondiabetic tissue and diabetic tissue (P < 0.001) (Fig. 5D).

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