Intervention With an Erythropoietin-Derived Peptide Protects Against Neuroglial and Vascular Degeneration During Diabetic Retinopathy.

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.

Eyes open to stem cells: safety trial may pave the way for cell therapy to treat retinal disease in patients

A clinical trial using human embryonic stem cell (hESC) therapy for an inherited retinal degenerative disease is about to commence. The Advanced Cell Technology (ACT) trial will treat patients with Stargardt's macular dystrophy using transplanted retinal pigment epithelium derived from hESCs. Currently, no effective treatment is available for Stargardt's disease so a stem cell-based therapy that can slow progression of this blinding condition could represent a significant breakthrough. While there are some hurdles to clear, the ACT trial is a fine example of translational research that could eventually pave the way for a range of stem cell therapies for the retina and other tissues.

Narrative on the Net:Bill and his hyper- lives, loves and texts

Narrative, by its very nature, is changing as a consequence of internet developments. Hypertexts are, for example, changing not just the way in which we disseminate information, but also the ways in which we write, speak and think. In this paper a narrative approach is taken to assess a case study of a person’s extensive home site on the web. Bill maintains an extensive web site documenting his life with Parkinson’s Disease, his love for running and all matters relating to the island of Montserrat in the Eastern Caribbean. Bill’s Parkinson’s Disease hypertext diary forms the focus of this case study of a life spent on-line. Though set up just as a diary about this progressively degenerative disease, because of its hypertextual qualities, this paper argues that it is through the diary that Bill comes to produce and sustain - to narrate - his identity. This paper thus contributes to the position that though hypertext encourages the construction of fragmented and false identity narratives, it is also a medium for sustaining linear and coherent representations of self-identity.

Investigation of the Human Brain Metabolome to Identify Potential Markers for Early Diagnosis and Therapeutic Targets of Alzheimer’s Disease

A study combining high resolution mass spectrometry (liquid chromatography-quadrupole time-of-flight-mass spectrometry, UPLC-QTof-MS) and chemometrics for the analysis of post-mortem brain tissue from subjects with Alzheimer’s disease (AD) (n = 15) and healthy age-matched controls (n = 15) was undertaken. The huge potential of this metabolomics approach for distinguishing AD cases is underlined by the correct prediction of disease status in 94–97% of cases. Predictive power was confirmed in a blind test set of 60 samples, reaching 100% diagnostic accuracy. The approach also indicated compounds significantly altered in concentration following the onset of human AD. Using orthogonal partial least-squares discriminant analysis (OPLS-DA), a multivariate model was created for both modes of acquisition explaining the maximum amount of variation between sample groups (Positive Mode-R2 = 97%; Q2 = 93%; root mean squared error of validation (RMSEV) = 13%; Negative Mode-R2 = 99%; Q2 = 92%; RMSEV = 15%). In brain extracts, 1264 and 1457 ions of interest were detected for the different modes of acquisition (positive and negative, respectively). Incorporation of gender into the model increased predictive accuracy and decreased RMSEV values. High resolution UPLC-QTof-MS has not previously been employed to biochemically profile post-mortem brain tissue, and the novel methods described and validated herein prove its potential for making new discoveries related to the etiology, pathophysiology, and treatment of degenerative brain disorders.

Foveal relocation surgery:Is it a reasonable option for patients with age-related macular degeneration?

Foveal relocation (or translocation) has been reintroduced recently as a possible treatment for patients with subfoveal choroidal neovascular membranes secondary to age-related macular degeneration and degenerative myopia. Different surgical techniques have been proposed and the results, although encouraging, are not completely satisfactory yet. Most surgical procedures described are technically difficult and require special vitreo-retinal expertise. Furthermore, although marked improvements in visual acuity have been observed in some patients, others do not experience visual improvement, even after a successful surgery. Additionally, devastating complications, such as proliferative vitreo-retinopathy (PVR) can occur, impairing the final visual outcome. Although foveal relocation surgery may be a promising direction in research and development, as yet, there is no randomised controlled trial to show that it is more effective than any other forms of treatment for macular degeneration. The validity of this surgical approach needs to be evaluated by the results of longer-term follow-up. This article reviews the current surgical techniques for foveal relocation, their outcomes and complications, and discusses the surgical problems that vitreo-retinal surgeons face when performing foveal relocation surgery.

Would people with Parkinson's disease benefit from palliative care?

Parkinson's disease (PD) is a chronic, progressive, degenerative disorder of the nervous system, causing substantial morbidity and has the capacity to shorten life. People with PD and their families can find the disease devastating. Nevertheless, this population of patients is not usually considered a group to be supported by palliative care specialists. But the nature of the illness and the challenges of managing its many physical and psychological effects raises questions about the potential benefits of a palliative care approach. The purpose of this project was to describe the experience of PD and consider the relevance of palliative care for this population. Semi-structured interviews were conducted with eight people with PD, 21 family caregivers and six health professionals. Five themes were developed from the data analysis: (1) emotional impact of diagnosis; (2) staying connected; (3) enduring financial hardship; (4) managing physical challenges; and (5) finding help for advanced stages. These data revealed that people with PD and family caregivers are confronted with similar issues to people with typical palliative care diagnoses, such as advanced cancer, and that a palliative approach may be helpful in the care of people with PD and their families.

Ionizing radiation and the retina

This review considers the effects of ionizing radiation on the retina and examines the relationship between the natural course of radiation retinopathy and the radiobiology of the retinal vascular endothelial cell (RVEC). Radiation retinopathy presents clinically as a progressive pattern of degenerative and proliferative vascular changes, chiefly affecting the macula, and ranging from capillary occlusion, dilation, and microaneurysm formation, to telangiectasia, intraretinal microvascular abnormalities, and neovascularization. The total-radiation dose and fractionation schedule are the major determinants for the time of onset, rate of progression, and severity of retinopathy, although other factors such as concomitant chemotherapy and preexisting diabetes may exaggerate the vasculopathy by intensifying the oxygen-derived free-radical assault on the vascular cells. The differential radiosensitivity of RVECs is attributed to their nuclear chromatin conformation, their antioxidant status, and their environment. We propose pathogenetic mechanisms for radiation retinopathy and suggest that the peculiar latency and unique clinical pattern is related to the life cycle of the RVEC. A rationale is also proposed for the use of radiotherapy in the treatment of subneovascularization and age-related macular degeneration.

The combined effects of diabetes and ionising radiation on the rat retina: an ultrastructural study

The combined effect of STZ-diabetes and ionising radiation on the rat retina was investigated. Wistar rats, which had been diabetic for 6 months, were irradiated with a single dose of x-rays (1500 cGy) and the ultrastructural effects evaluated at 4-10 mths post-irradiation. At 4 months post-irradiation, the outer nuclear layer of the retina was greatly reduced in thickness and the photoreceptor outer segments were disorganised and reduced in length. In addition, the nerve fibre layer contained many cytoid bodies and there were many redundant basement membrane tubes throughout the inner retina. By 6 months post-irradiation, the photoreceptor cells were virtually absent, bringing the external limiting membrane into close apposition to the RPE. Throughout large areas of the outer retina, RPE cells were hypertrophic and some had proliferated into the inner retina. In many regions, proliferating retinal capillaries were observed within the RPE layer, and at 8 months post-irradiation, some vessels extended into the inner retina accompanied by RPE cells. At 10 months post-irradiation, the RPE was atrophic and degenerative with retinal glial cells coming into contact with Bruch's membrane. In some areas, the glia which had breached Bruch's membrane had invaded the underlying choroid. Where glial cells contacted the choriocapillaries, the vessels assumed the appearance of retinal vessels with plump endothelia and no fenestrations. This study has described a progressive inner retinal ischemia, with cytoid bodies, capillary non-perfusion and general atrophy of the inner retina intensifying markedly with increasing post-irradiation time.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of signalling in non-erythroid cells by pharmacological levels of erythropoietin

Erythropoiesis is maintained by the hormone erythropoietin (Epo) binding to its cognate receptor (EpoR) on erythroid progenitor cells. The Epo-EpoR interaction initiates a signal transduction process that regulates the survival, growth and differentiation of these cells. Originally perceived as highly lineage-restricted, Epo is now recognised to have pleiotropic effects extending beyond the maintenance of red cell mass. Functional interactions between Epo and EpoR have been demonstrated in numerous cells and tissues. EpoR expression on neoplastic cells leads to concern that recombinant human erythropoietin, used to treat anaemia in cancer patients, may augment tumour growth. Here we demonstrate that EPO, at pharmacological concentrations, can activate three major signalling cascades, viz. the Jak2/STAT5, Ras/ERK and PI3K/Akt pathways in non-small cell lung carcinoma (NSCLC) cell lines. EpoR synthesis is normally under the control of GATA-1, but NSCLC cells exhibit decreased GATA-1 levels compared to GATA-2, -3 and -6, suggesting that GATA-1 is not essential for EpoR production. The increased Epo-induced signalling was not associated with a growth advantage for the NSCLC cells.

Loss of Synaptic Connectivity, Particularly in Second Order Neurons Is a Key Feature of Diabetic Retinal Neuropathy in the Ins2Akita Mouse

Retinal neurodegeneration is a key component of diabetic retinopathy (DR), although the detailed neuronal damage remains ill-defined. Recent evidence suggests that in addition to amacrine and ganglion cell, diabetes may also impact on other retinal neurons. In this study, we examined retinal degenerative changes in Ins2^Akita diabetic mice. In scotopic electroretinograms (ERG), b-wave and oscillatory potentials were severely impaired in 9-month old Ins2^Akita mice. Despite no obvious pathology in fundoscopic examination, optical coherence tomography (OCT) revealed a progressive thinning of the retina from 3 months onwards. Cone but not rod photoreceptor loss was observed in 3-month-old diabetic mice. Severe impairment of synaptic connectivity at the outer plexiform layer (OPL) was detected in 9-month old Ins2Akita mice. Specifically, photoreceptor presynaptic ribbons were reduced by 25% and postsynaptic boutons by 70%, although the density of horizontal, rod- and cone-bipolar cells remained similar to non-diabetic controls. Significant reductions in GABAergic and glycinergic amacrine cells and Brn3a+ retinal ganglion cells were also observed in 9-month old Ins2^Akita mice. In conclusion, the Ins2^Akita mouse develops cone photoreceptor degeneration and the impairment of synaptic connectivity at the OPL, predominately resulting from the loss of postsynaptic terminal boutons. Our findings suggest that the Ins2^Akita mouse is a good model to study diabetic retinal neuropathy.

Role of saphenous vein wall in the pathogenesis of primary varicose veins

UNLABELLED: Varicose veins may be due to weakness of the vein wall as a result of structural problems. There are conflicting findings in the literature about these problems especially concerning collagen, elastin and smooth muscle cells content. The aim of this study was to look at the structural abnormalities of varicose veins (with and without valvular incompetence).

MATERIALS AND METHODS: We studied 70 specimens of long saphenous veins from 35 patients (24 with varicose and 11 with normal veins). Two specimens were taken from each vein approximately 3-4 cm from the saphenofemoral junction. Vein specimens were processed for histological and electron microscopic studies. Both qualitative and quantitative analyses were performed to assess the degree of wall changes. Using the image analyzer, contents of collagen, elastin and smooth muscle cells, in addition to intimal and medial thickness, were measured.

RESULTS: Light microscopy revealed significant increase in intimal and medial thickness and collagen content of media and significant decrease in elastin content in varicose veins compared with normal veins. There was no statistical significant difference between varicose veins with and without saphenofemoral valve incompetence. Electron microscopy showed marked degenerative changes in intima and media of varicose veins.

CONCLUSION: The findings in our study supported the theory of primary weakness of the vein wall as a cause of varicosity. This weakness is due to intimal changes, disturbance in the connective tissue components and smooth muscle cells.

Role of the receptor for advanced glycation endproducts (RAGE) in retinal vasodegenerative pathology during diabetes in mice

Aims/hypothesis
The receptor for AGEs (RAGE) is linked to proinflammatory pathology in a range of tissues. The objective of this study was to assess the potential modulatory role of RAGE in diabetic retinopathy.
Methods
Diabetes was induced in wild-type (WT) and Rage −/− mice (also known as Ager −/− mice) using streptozotocin while non-diabetic control mice received saline. For all groups, blood glucose, HbA1c and retinal levels of methylglyoxal (MG) were evaluated up to 24 weeks post diabetes induction. After mice were killed, retinal glia and microglial activation, vasopermeability, leucostasis and degenerative microvasculature changes were determined. 

Results
Retinal expression of RAGE in WT diabetic mice was increased after 12 weeks (p < 0.01) but not after 24 weeks. Rage −/− mice showed comparable diabetes but accumulated less MG and this corresponded to enhanced activity of the MG-detoxifying enzyme glyoxalase I in their retina when compared with WT mice. Diabetic Rage −/− mice showed significantly less vasopermeability, leucostasis and microglial activation (p < 0.05–0.001). Rage −/− mice were also protected against diabetes-related retinal acellular capillary formation (p < 0.001) but not against pericyte loss. 

Conclusions/interpretation Rage −/− in diabetic mice is protective against many retinopathic lesions, especially those related to innate immune responses. Inhibition of RAGE could be a therapeutic option to prevent diabetic retinopathy.

Wnt signaling in age-related macular degeneration: human macular tissue and mouse model

BACKGROUND: The wingless-type MMTV integration site (Wnt) signaling is a group of signal transduction pathways. In canonical Wnt pathway, Wnt ligands bind to low-density lipoprotein receptor-related protein 5 or 6 (LRP5 or LRP6), resulting in phosphorylation and activation of the receptor. We hypothesize that canonical Wnt pathway plays a role in the retinal lesion of age-related macular degeneration (AMD), a leading cause of irreversible central visual loss in elderly.

METHODS: We examined LRP6 phosphorylation and Wnt signaling cascade in human retinal sections and plasma kallistatin, an endogenous inhibitor of the Wnt pathway in AMD patients and non-AMD subjects. We also used the Ccl2 (-/-) /Cx3cr1 (-/-) /rd8 and Ccl2 (-/-) /Cx3cr1 (gfp/gfp) mouse models with AMD-like retinal degeneration to further explore the involvement of Wnt signaling activation in the retinal lesions in those models and to preclinically evaluate the role of Wnt signaling suppression as a potential therapeutic option for AMD.

RESULTS: We found higher levels of LRP6 (a key Wnt signaling receptor) protein phosphorylation and transcripts of the Wnt pathway-targeted genes, as well as higher beta-catenin protein in AMD macula compared to controls. Kallistatin was decreased in the plasma of AMD patients. Retinal non-phosphorylated-β-catenin and phosphorylated-LRP6 were higher in Ccl2 (-/-) /Cx3cr1 (-/-) /rd8 mice than that in wild type. Intravitreal administration of an anti-LRP6 antibody slowed the progression of retinal lesions in Ccl2 (-/-) /Cx3cr1 (-/-) /rd8 and Ccl2 (-/-) /Cx3cr1 (gfp/gfp) mice. Electroretinography of treated eyes exhibited larger amplitudes compared to controls in both mouse models. A2E, a retinoid byproduct associated with AMD was lower in the treated eyes of Ccl2 (-/-) /Cx3cr1 (-/-) /rd8 mice. Anti-LRP6 also suppressed the expression of Tnf-α and Icam-1 in Ccl2 (-/-) /Cx3cr1 (-/-) /rd8 retinas.

CONCLUSIONS: Wnt signaling may be disturbed in AMD patients, which could contribute to the retinal inflammation and increased A2E levels found in AMD. Aberrant activation of canonical Wnt signaling might also contribute to the focal retinal degenerative lesions of mouse models with Ccl2 and Cx3cr1 deficiency, and intravitreal administration of anti-LRP6 antibody could be beneficial by deactivating the canonical Wnt pathway.

Targeting translocator protein (18 kDa) (TSPO) dampens pro-inflammatory microglia reactivity in the retina and protects from degeneration

BACKGROUND: Reactive microglia are commonly seen in retinal degenerative diseases, and neurotoxic microglia responses can contribute to photoreceptor cell death. We and others have previously shown that translocator protein (18 kDa) (TSPO) is highly induced in retinal degenerations and that the selective TSPO ligand XBD173 (AC-5216, emapunil) exerts strong anti-inflammatory effects on microglia in vitro and ex vivo. Here, we investigated whether targeting TSPO with XBD173 has immuno-modulatory and neuroprotective functions in two mouse models of acute retinal degeneration using bright white light exposure.

METHODS: BALB/cJ and Cx3cr1 (GFP/+) mice received intraperitoneal injections of 10 mg/kg XBD173 or vehicle for five consecutive days, starting 1 day prior to exposure to either 15,000 lux white light for 1 h or 50,000 lux focal light for 10 min, respectively. The effects of XBD173 treatment on microglia and Müller cell reactivity were analyzed by immuno-stainings of retinal sections and flat mounts, fluorescence-activated cell sorting (FACS) analysis, and mRNA expression of microglia markers using quantitative real-time PCR (qRT-PCR). Optical coherence tomography (OCT), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) stainings, and morphometric analyses were used to quantify the extent of retinal degeneration and photoreceptor apoptosis.

RESULTS: Four days after the mice were challenged with bright white light, a large number of amoeboid-shaped alerted microglia appeared in the degenerating outer retina, which was nearly completely prevented by treatment with XBD173. This treatment also down-regulated the expression of TSPO protein in microglia but did not change the TSPO levels in the retinal pigment epithelium (RPE). RT-PCR analysis showed that the microglia/macrophage markers Cd68 and activated microglia/macrophage whey acidic protein (Amwap) as well as the pro-inflammatory genes Ccl2 and Il6 were reduced after XBD173 treatment. Light-induced degeneration of the outer retina was nearly fully blocked by XBD173 treatment. We further confirmed these findings in an independent mouse model of focal light damage. Retinas of animals receiving XBD173 therapy displayed significantly more ramified non-reactive microglia and more viable arrestin-positive cone photoreceptors than vehicle controls.

CONCLUSIONS: Targeting TSPO with XBD173 effectively counter-regulates microgliosis and ameliorates light-induced retinal damage, highlighting a new pharmacological concept for the treatment of retinal degenerations.

Retinal pigment epithelial cell multinucleation in the aging eye - a mechanism to repair damage and maintain homoeostasis

Retinal pigment epithelial (RPE) cells are central to retinal health and homoeostasis. Dysfunction or death of RPE cells underlies many age-related retinal degenerative disorders particularly age-related macular degeneration. During aging RPE cells decline in number, suggesting an age-dependent cell loss. RPE cells are considered to be postmitotic, and how they repair damage during aging remains poorly defined. We show that RPE cells increase in size and become multinucleate during aging in C57BL/6J mice. Multinucleation appeared not to be due to cell fusion, but to incomplete cell division, that is failure of cytokinesis. Interestingly, the phagocytic activity of multinucleate RPE cells was not different from that of mononuclear RPE cells. Furthermore, exposure of RPE cells in vitro to photoreceptor outer segment (POS), particularly oxidized POS, dose-dependently promoted multinucleation and suppressed cell proliferation. Both failure of cytokinesis and suppression of proliferation required contact with POS. Exposure to POS also induced reactive oxygen species and DNA oxidation in RPE cells. We propose that RPE cells have the potential to proliferate in vivo and to repair defects in the monolayer. We further propose that the conventionally accepted 'postmitotic' status of RPE cells is due to a modified form of contact inhibition mediated by POS and that RPE cells are released from this state when contact with POS is lost. This is seen in long-standing rhegmatogenous retinal detachment as overtly proliferating RPE cells (proliferative vitreoretinopathy) and more subtly as multinucleation during normal aging. Age-related oxidative stress may promote failure of cytokinesis and multinucleation in RPE cells.