Association of Body Mass Index and Waist-to-Hip Ratio With Retinal Microvasculature in Healthy Chinese Adults: An Optical Coherence Tomography Angiography Study.

PURPOSE: To investigate the association of body mass index (BMI) and waist-to-hip ratio (WHR) with macular vessel density (VD) and foveal avascular zone (FAZ), using optical coherence tomography angiography (OCTA), in healthy Chinese adults. DESIGN: Cross-sectional study. METHODS: A total of 1555 Chinese adults aged ≥ 50 years with no history of ocular disease were recruited from communities in Guangzhou, China. The OCTA was performed with a 6 × 6 mm macular angiography model. The FAZ of the superficial capillary plexus (SCP), and VD of SCP and deep capillary plexus (DCP) were calculated. Univariable and multivariable linear regression analyses were used to evaluate the effect of BMI and WHR on VD and FAZ. RESULTS: The VD of the SCP increased as BMI increased, with average measurements of 39.30 ± 2.14 for normal, 39.52 ± 2.07 for overweight, and 39.76 ± 2.03 for obesity (P = .001). The VD of the DCP also increased with increasing BMI (P = .009). Multiple regression models confirmed a positive association between generalized obesity and superficial VD in the whole image (ß = 0.350, P = .008), inner circle (ß = 0.431, P = .032), and outer circle (ß = 0.368, P = .005). After adjusting for confounders, tertile 3 of the WHR level was positively associated with superficial VD (ß = 0.472, P = .033) and deep VD (ß = 0.422, P = .034) only in the inner circle. CONCLUSIONS: Generalized obesity was associated with increased superficial VD, while abdominal obesity was associated with increased superficial and deep VD only in the inner circle. Different manifestations of the retinal microvasculature may reflect distinct roles of body composition on macular vessel alterations and disease occurrence.

Biological features of the pecten oculi of the European wild quail (Coturnix coturnix): Adaptative habits to Northern Egyptian coast with novel vision to its SEM-EDX analysis.

The present investigation was prepared to give a complete ultrastructural characterization of the pecten oculi of the diurnal European wild Quail to describe their adaptation habits to the Northern Egyptian coast. Our work declares the first endeavor is the elemental analysis using scanning electron microscopy-energy dispersive X-ray (SEM-EDX) to show the migration effect on their eye. The intra-ocular quadrilateral trapezoid black pigmented plicated type pecten oculi were observed on the postero-inferior wall of the eyeball with craniocaudal and posterio-anterior directions along the fetal fissure. The pecten oculi consist of three parts: the basal, body, and apical. The basal part originated behind the optic nerve, forming the slightly elevated border, while the apical part was directed toward the ciliary body. There are 10-11 pleats with interpleat space. The coiled surface refers to numerous capillary vessels. The smooth head of each pleat was kidney-like, strongly attached to a bridge. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. There are numerous melanosomes and little hyalocytes on the pecteneal pleat's outer surfaces. The thick basal part of each pleat had numerous thick longitudinal microfolds that refer to the numerous blood capillaries attached to the retina as supporting roots. SEM/EDX elemental analysis revealed that carbon is the highest element (half), while oxygen represents about one-third. In the meantime, the lowest element is the phosphate at the apical part, while the lowest element in the rest is the sulfate. Finally, the pecten oculi are thought to be a reflection of the avian lifestyle and ecological adaptations. HIGHLIGHTS: Our work is the first description of the elemental analysis using SEM-EDX to show the migration effect on their eye. The quadrilateral trapezoid black pigmented plicated type pecten oculi were observed on the postero-inferior wall of the eyeball with cranio-caudal and posterio-anterior directions along the fetal fissure. The basal part of the pecten oculi originated behind the optic nerve, forming the slightly elevated border, while the apical part was directed toward the ciliary body. There are 10-11 pleats with interpleat space. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. There are numerous melanosomes and little hyalocytes on the pecteneal pleat's outer surfaces. SEM/EDX elemental analysis revealed that carbon is the highest element (half percent), while oxygen represents about one-third of the element's percent meanwhile, the lowest element is phosphate at the apical part, while the lowest element in the rest is the sulfate.

Gross, ultrastructural, and histological characterizations of pecten oculi of the glossy ibis (Plegadis falcinellus): New insights into its scanning electron microscope-energy dispersive X-ray analysis.

The current study shows the first attempts to clarify the gross, ultrastructure, and histological properties of the pecten oculi of the diurnal, visually active glossy ibis, as well as scanning electron microscope-energy dispersive X-ray (SEM-EDX) image analysis (Plegadis falcinellus). The pecten oculi was found on the eyeball's posteroinferior wall, adjacent to the optic nerve in both the craniocaudal and posterio-anterior directions. The plicated quadrilateral black pigmented pecten oculi consisted of a base, 10-12 pleats, and an apex. The base was joined by an elevated ridge and derived from the non-vascular retina, while the apex was not a fused part and was found neighboring the gelatinous vitreous body. The limited interpleat spaces were somewhat wider at the base of the pecten oculi. The outer surface of each highly vascular pecten pleat revealed a tortious coiled formation due to the existence of a considerable number of capillary vessels. The outer pleat surfaces had a vitreopecteneal limiting membrane that segregated the pecten pleats from the vitreous body. The high SEM magnification revealed that there are considerable plentiful hyalocyte cells on the outer surface of the pleats. The SEM-EDX analysis of the elementary formatting of the pecten oculi (at apex, middle, and base) clarified that the carbon represents the highest and a half percent. Furthermore, oxygen represents one-third of all elemental composition in the three regions, while the lowest percentage is calcium. Finally, the pecten oculi characterizations of this migratory bird on the Northern Egyptian shore were associated with their adaptive dietary strategies.

Ultrastructural characterizations of the pecten oculi of the common ostrich (Struthio camelus): New insight to scanning electron microscope-energy dispersive X-ray analysis.

The current observation was designed to give a complete ultrastructural description of the pecten oculi of the common ostrich (Struthio camelus). Moreover, this study represents the first attempt to measurements the elements composition of the pecten oculi using scanning electron microscope-energy dispersive X-ray (SEM-EDX) at three regions (apical, body, and basal). To accomplish this study, eight ostrich were examined grossly and under the electron microscope. The vaned-shaped pecten oculi consisted of three regions (apex, body, and base) with 24-25 plates. The pecten oculi was located postero-anteriorly near to the optic nerve disc that was attached by their bases to the retina forming a slightly elevated basal border joining the bases of all pleats, while the apex was linked in a circular bridge. The pleats are separated from each other by the inter-pleat spaces that are very clear at the base and nearly not observed at the apical part. The outer pleat's surface carried numerous prominences that pointed to the existence of numerous afferent and efferent pecteneal blood capillaries vessels. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. Our findings concluded that, the high number of thick pecteneal pleats was related to the diurnal activity of the common ostrich. SEM-EDX shows that the carbon percentage in the three regions is the highest that representing about half of all elements, while the oxygen percent is about one-third; meanwhile, the lowest percentage is the sulfate at the apical region, and the calcium at the body and basal regions.

VDAC1 regulates mitophagy in NLRP3 inflammasome activation in retinal capillary endothelial cells under high-glucose conditions.

Diabetic retinopathy (DR) has been considered to involve mitochondrial alterations and be related to the nucleotide-binding oligomerization domain-like receptors 3 (NLRP3) inflammasome activation. The voltage-dependent anion channel 1 (VDAC1) protein is one of the key proteins that regulates the metabolic and energetic functions of the mitochondria. To explore the involvement of VDAC1 in mitophagy regulation of NLRP3 inflammasome activation under high-glucose (HG) conditions, this study examined expressions of VDAC1, mitochondrial function and mitophagy-related proteins, and NLRP3 inflammasome-related proteins in human retinal capillary endothelial cells (HRCECs) cultured with 30 mM of glucose in the presence or absence of mitophagy inhibitor (Mdivi-1) using Western blot. Mitochondrial membrane potential and mitochondrial reactive oxygen species (mtROS) were detected using flow cytometry. GFP-tagged pAdTrack-VDAC1 adenovirus was used to overexpress VDAC1. Cell biological behaviors, including proliferation, migration, tubule formation, and apoptosis, were also observed. Our results showed that when compared to the normal glucose and high mannitol groups, increased amounts of mitochondrial fragments, reduced mitochondrial membrane potential, increased expression of mitochondrial fission protein Drp 1, decreased expression of mitochondrial fusion protein Mfn 2, accumulation of mtROS, and activation of the NLRP3 inflammasome were observed in the HG group. Meanwhile, HG markedly reduced the protein expressions of PINK1, Parkin and VDAC1. Inhibition of mitophagy reduced PINK1 expression, enhanced NLRP3 expression, but failed to alter VDAC1. VDAC1 overexpression promoted PINK1 expression, inhibited NLRP3 activation and changed the cell biological behaviors under HG conditions. These findings demonstrate that VDAC1-mediated mitophagy plays a crucial role in regulating NLRP3 inflammasome activation in retinal capillary endothelial cells under HG conditions, suggesting that VDAC1 may be a potential target for preventing or treating DR.

Light and electron microscopic studies on the pecten oculi showing blood-retina barrier properties in Turkey's native Gerze chicken.

The pecten oculi is a highly vascularized and pigmented organ that projects from the optic disc into the vitreous body in the avian eye. In this study, the pecten oculi of Turkey's native Gerze chicken was examined by light and scanning electron microscopy. Furthermore, the localization of some adherens junction components (E-cadherin and pan-cadherin) in intact vessels of the blood-retina barrier was investigated by immunohistochemistry. In the Gerze chicken, the pecten oculi was a thin structure, which was located over the head of the discus nervi optici and projected from the retina into the corpus vitreum. The pecten oculi consisted of 18-21 highly vascularized pleats, joined apically by a bridge and resembled an accordion in appearance. Hyalocytes and melanocytes were observed around the small and large vessels. The morphometric data of the pecten oculi showed that there were no statistical differences in terms of sex. The immunohistochemical analysis of the pecten oculi, which is used as a model for the investigation of the formation and maturation of the barrier properties in the central nervous system, revealed cytoplasmic E-cadherin and pan-cadherin immunoreactivity in the endothelial cells of the small, large and capillary vessels. These observations suggest that while the morphological and histological structure of the Gerze chicken's pecten oculi was generally similar to that of other diurnal domestic birds, the pecten oculi, a model system for vascular differentiation and the blood-retina barrier, expressed different cadherins.

Evolutionary Compression of Deep Neural Networks for Biomedical Image Segmentation.

Biomedical image segmentation is lately dominated by deep neural networks (DNNs) due to their surpassing expert-level performance. However, the existing DNN models for biomedical image segmentation are generally highly parameterized, which severely impede their deployment on real-time platforms and portable devices. To tackle this difficulty, we propose an evolutionary compression method (ECDNN) to automatically discover efficient DNN architectures for biomedical image segmentation. Different from the existing studies, ECDNN can optimize network loss and number of parameters simultaneously during the evolution, and search for a set of Pareto-optimal solutions in a single run, which is useful for quantifying the tradeoff in satisfying different objectives, and flexible for compressing DNN when preference information is uncertain. In particular, a set of novel genetic operators is proposed for automatically identifying less important filters over the whole network. Moreover, a pruning operator is designed for eliminating convolutional filters from layers involved in feature map concatenation, which is commonly adopted in DNN architectures for capturing multi-level features from biomedical images. Experiments carried out on compressing DNN for retinal vessel and neuronal membrane segmentation tasks show that ECDNN can not only improve the performance without any retraining but also discover efficient network architectures that well maintain the performance. The superiority of the proposed method is further validated by comparison with the state-of-the-art methods.

A comparative ultrastructural study of the pecten oculi in adult, juvenile, and nestling yellow-legged gulls, Larus michahellis (Naumann, 1840).

This study aimed at examining the histological structure of the pecten oculi in the adult yellow-legged gull, Larus michahellis, and at two moments of postnatal development: during the posthatch (nestling) and juvenile periods. Particular attention was paid to differences in the diameter of vessels, the thickness of the basement membrane, and ultrastructural features of endothelial and pigmented stromal cells. Capillary endothelial cells displayed numerous microvillous-like folds projecting from their internal and external surfaces. Intercellular spaces between capillaries were occupied by pigmented stromal cells. The ultrastructure of pecten oculi underwent noticeable changes during postnatal development. The examination of the capillaries in nestlings, juveniles, and adults revealed that the formation process of vessels and pigmented stromal cells did not complete itself in the posthaching phase. The prominent feature of endothelial cells of capillaries in nestlings was that the microvilli were longer than in juvenile and adult cells, and the capillary lumen was therefore reduced. In this sense, their pigmented stromal cells showed fewer melanosomes, lacked intercellular spaces, and cellular junctions could still be observed. These results provide evidence that the pecten oculi during the posthatching phase maintains immature morphological features consistent with a role of pigmented stromal cells in the blood-retina barrier.

Exosomes derived from platelet-rich plasma mediate hyperglycemia-induced retinal endothelial injury via targeting the TLR4 signaling pathway.

In this study, we aimed to investigate whether exosomes derived from platelet-rich plasma (PRP-Exos) can regulate hyperglycemia-induced retinal injury via targeting the TLR4 signaling pathway. We studied the effects of PRP-Exos on retinal endothelial injury in diabetic rats and human retinal endothelial cells (HRECs) in vitro. Isolated PRP-Exos were observed by transmission electron microscopy and flow cytometry. Samples were obtained from the retinas of rats and cultured HRECs after treatment to analyze reactive oxygen species levels. Immunofluorescence and Western blotting were conducted to assess the levels of adhesion molecules and the TLR4 signaling pathway. The content of CXCL10 in PRP-Exos was analyzed by Western blot. The plasma level of PRP-Exos was greatly increased in diabetic rats. In cultured HRECs, PRP-Exos induced the production of malonyldialdehyde(MDA) and reactive oxygen species(ROS) and inhibited the activity of superoxide dismutase(SOD). Further analysis showed that the activation of the TLR4 pathway by PRP-Exos played a pivotal role in regulating inflammation. The inhibition of the TLR4 pathway by TAK-242 had a robust protective effect on PRP-Exo-induced retinal endothelial injury in vitro and vivo. In addition, PRP-Exo-derived CXCL10 led to retinal endothelial injury, and antagonizing CXCL10 with a CXCL10-neutralizing antibody dramatically attenuated such injury. In summary, PRP-Exos mediate hyperglycemia-induced retinal endothelial injury by upregulating the TLR4 signaling pathway.

The long dystrophin gene product Dp427 modulates retinal function and vascular morphology in response to age and retinal ischemia.

Mutations in dystrophin are the major cause of muscular dystrophies. Continuous muscular degeneration and late stage complications, including cardiomyopathy and respiratory insufficiency, dominate the clinical phenotype. Gene expression and regulation of the dystrophin gene outside of muscular tissue is far more complex. Multiple tissue-specific dystrophin gene products are widely expressed throughout the body, including the central nervous system and eye, predisposing affected patients to secondary complications in non-muscular tissues. In this study, we evaluated the impact of the full-length dystrophin gene product, Dp427, on retinal homeostasis and angiogenesis. Based on the clinical case of a Duchenne muscular dystrophy (DMD) patient who developed severe fibrovascular changes in the retina in response to hypoxic stress, we hypothesized that defects in Dp427 make the retina more susceptible to stresses such as ageing and ischemia. To further study this, a mouse strain lacking Dp427 expression (Mdx) was studied during retinal development, ageing and in the oxygen-induced retinopathy (OIR) model. While retinal vascular morphology was normal during development and ageing, retinal function measured by electroretinography (ERG) was slightly reduced in young adult Mdx mice and deteriorated with age. Mdx mice also had increased retinal neovascularization in response to OIR and more pronounced long-term deterioration in retinal function following OIR. Based on these results, we suggest that DMD patients with a mutation in Dp427 may experience disturbed retinal homeostasis with increasing age and therefore be prone to develop excessive retinal neovascular changes in response to hypoxic stress. DMD patients in late disease stages should, thus, be regularly examined to detect asymptomatic retinal abnormalities and prevent visual impairment.

ELOVL4-Mediated Production of Very Long-Chain Ceramides Stabilizes Tight Junctions and Prevents Diabetes-Induced Retinal Vascular Permeability.

Tight junctions (TJs) involve close apposition of transmembrane proteins between cells. Although TJ proteins have been studied in detail, the role of lipids is largely unknown. We addressed the role of very long-chain (VLC ≥26) ceramides in TJs using diabetes-induced loss of the blood-retinal barrier as a model. VLC fatty acids that incorporate into VLC ceramides are produced by elongase elongation of very long-chain fatty acids protein 4 (ELOVL4). ELOVL4 is significantly reduced in the diabetic retina. Overexpression of ELOVL4 significantly decreased basal permeability, inhibited vascular endothelial growth factor (VEGF)- and interleukin-1ß-induced permeability, and prevented VEGF-induced decrease in occludin expression and border staining of TJ proteins ZO-1 and claudin-5. Intravitreal delivery of AAV2-hELOVL4 reduced diabetes-induced increase in vascular permeability. Ultrastructure and lipidomic analysis revealed that ω-linked acyl-VLC ceramides colocalize with TJ complexes. Overall, normalization of retinal ELOVL4 expression could prevent blood-retinal barrier dysregulation in diabetic retinopathy through an increase in VLC ceramides and stabilization of TJs.

ROCK-1 mediates diabetes-induced retinal pigment epithelial and endothelial cell blebbing: Contribution to diabetic retinopathy.

In diabetic retinopathy, the exact mechanisms leading to retinal capillary closure and to retinal barriers breakdown remain imperfectly understood. Rho-associated kinase (ROCK), an effector of the small GTPase Rho, involved in cytoskeleton dynamic regulation and cell polarity is activated by hyperglycemia. In one year-old Goto Kakizaki (GK) type 2 diabetic rats retina, ROCK-1 activation was assessed by its cellular distribution and by phosphorylation of its substrates, MYPT1 and MLC. In both GK rat and in human type 2 diabetic retinas, ROCK-1 is activated and associated with non-apoptotic membrane blebbing in retinal vessels and in retinal pigment epithelium (RPE) that respectively form the inner and the outer barriers. Activation of ROCK-1 induces focal vascular constrictions, endoluminal blebbing and subsequent retinal hypoxia. In RPE cells, actin cytoskeleton remodeling and membrane blebs in RPE cells contributes to outer barrier breakdown. Intraocular injection of fasudil, significantly reduces both retinal hypoxia and RPE barrier breakdown. Diabetes-induced cell blebbing may contribute to ischemic maculopathy and represent an intervention target.

Cellular Senescence Is Associated With Human Retinal Microaneurysm Formation During Aging.

Purpose: Microaneurysms are present in healthy old-age human retinas. However, to date, no age-related pathogenic mechanism has been implicated in their formation. Here, cellular senescence, a hallmark of aging and several age-related diseases, has been analyzed in the old-age human retina and in the retina of a progeric mouse. Methods: Retinas were obtained from 17 nondiabetic donors and from mice deficient in Bmi1. Cellular senescence was analyzed by immunohistochemistry, senescent-associated ß-galactosidase activity assay, Sudan black B staining, conventional transmission electron microscopy, and immunoelectronmicroscopy. Results: Neurons, but not neuroglia, and blood vessels undergo cellular senescence in the old-age human retina. The canonical senescence markers p16, p53, and p21 were up-regulated and coexisted with apoptosis in old-age human microaneurysms. Senescent endothelial cells were discontinuously covered by fibronectin, and p16 colocalized with the ß1 subunit of fibronectin receptor α5ß1 integrin under the endothelial cellular membrane, suggesting anoikis as a mechanism involved in endothelial cell apoptosis. In a progeric mouse model deficient in Bmi1, where p21 was overexpressed, the retinal blood vessels displayed an aging phenotype characterized by enlarged caveolae and lipofuscin accumulation. Although mouse retina is not prone to develop microaneurysms, Bmi1-deficient mice presented abundant retinal microaneurysms. Conclusions: Together, these results uncover cellular senescence as a player during the formation of microaneurysms in old-age human retinas.

The role of FoxO1 in interleukin-1ß-induced autostimulation in retina endothelial cells and retinas of diabetic rats.

Diabetic retinopathy is a chronic, low-grade inflammatory disease. The present study aimed to investigate the effect of forkhead transcription factor O1 (FoxO1) expression on interleukin-1ß (IL-1ß)-induced autostimulation, both in vitro in human retina microvascular endothelial cells (HRMECs), and in vivo in retinas isolated from streptozotocin-induced diabetic rats. High-glucose (HG) and recombinant IL-1ß treatment were both shown to increase the expression of FoxO1 and IL-1ß in HRMECs in a dose-dependent manner. IL-1 receptor antagonist (IL-1RA) and mitogen-activated protein kinase (MAPK) inhibitors reduced IL-1ß-induced expression of FoxO1 in HRMECs. Moreover, the increased expressions of FoxO1 and IL-1ß in the retinas of diabetic rats were significantly decreased by intravitreal injection of lentiviral vector-mediated FoxO1 small-interfering RNA. Together, these results suggest that HG triggers IL-1ß synthesis in HRMECs. The produced IL-1ß induces increased FoxO1 expression, as well as interacts with the IL-1 receptor to activate MAPK signaling and thereby induces IL-1ß autostimulation. The IL-1ß-induced autostimulation can be inhibited by downregulation of FoxO1, accompanied by a reduction of inflammation. Together, these findings identify novel functions for FoxO1 and IL-1ß in diabetic retinopathy.

Macroanatomic, light, and electron microscopic examination of pecten oculi in the seagull (Larus canus).

The present study was conducted to determine macroanatomic characteristic as well as light and electron microscopic examination (SEM) of pecten oculi and totally 20 bulbus oculi belonging to 10 seagulls (Larus canus) were used. Pecten oculi formations consisted of 18 to 21 pleats and their shape looked like a snail. Apical length of the pleats forming pecten oculi were averagely measured as 5.77 ± 0.56 mm, retina-dependent base length was 9.01 ± 1.35 mm and height was measured as 6.4 ± 0.62 mm. In pecten oculi formations which extend up to 1/3 of the bulbus oculi, two different vascular formations were determined according to thickness of the vessel diameter. Among these, vessels with larger diameters which are less than the others in count were classified as afferent and efferent vessels, smaller vessels which are greater in size were classified as capillaries. Furthermore, the granules which were observed intensely in apical side of the pleats of pecten oculi were observed to distribute randomly along the plica.

Nucleoside diphosphate kinase B regulates angiogenic responses in the endothelium via caveolae formation and c-Src-mediated caveolin-1 phosphorylation.

Nucleoside diphosphate kinase B (NDPK-B) is an enzyme required for nucleoside triphosphate homeostasis, which has been shown to interact with caveolin-1 (Cav-1). In endothelial cells (ECs), NDPK-B contributes to the regulation of angiogenesis and adherens junction (AJ) integrity. We therefore investigated whether an interaction of NDPK-B with Cav-1 in ECs is required for this regulation and the involvement of VEGF signaling herein. We report that simultaneous depletion of NDPK-B/Cav-1 in HUVECs synergistically impaired sprouting angiogenesis. NDPK-B depletion alone impaired caveolae formation, VEGF-induced phosphorylation of c-Src/Cav-1 but not of ERK1/2/AKT/eNOS. In vivo, Cav-1-/- mice showed impaired retinal vascularization at postnatal-day five, whereas NDPK-B-/- mice did not. Primary mouse brain ECs (MBMECs) from NDPK-B-/- mice showed no change in caveolae content and transendothelial-electrical resistance upon VEGF stimulation. Interestingly, NDPK-B-/- MBMECs displayed an accumulation of intracellular vesicles and increased Cav-1 levels. Dextran tracer analysis showed increased vascular permeability in the brain of NDPK-B-/- mice compared to wild type. In conclusion, our data indicate that NDPK-B is required for the correct localization of Cav-1 at the plasma membrane and the formation of caveolae. The genetic ablation of NDPK-B could partially be compensated by an increased Cav-1 content, which restored caveolae formation and some endothelial functions.

Zingiber officinale attenuates retinal microvascular changes in diabetic rats via anti-inflammatory and antiangiogenic mechanisms.

PURPOSE: Diabetic retinopathy is a common microvascular complication of long-standing diabetes. Several complex interconnecting biochemical pathways are activated in response to hyperglycemia. These pathways culminate into proinflammatory and angiogenic effects that bring about structural and functional damage to the retinal vasculature. Since Zingiber officinale (ginger) is known for its anti-inflammatory and antiangiogenic properties, we investigated the effects of its extract standardized to 5% 6-gingerol, the major active constituent of ginger, in attenuating retinal microvascular changes in rats with streptozotocin-induced diabetes. METHODS: Diabetic rats were treated orally with the vehicle or the ginger extract (75 mg/kg/day) over a period of 24 weeks along with regular monitoring of bodyweight and blood glucose and weekly fundus photography. At the end of the 24-week treatment, the retinas were isolated for histopathological examination under a light microscope, transmission electron microscopy, and determination of the retinal tumor necrosis factor-α (TNF-α), nuclear factor-kappa B (NF-κB), and vascular endothelial growth factor (VEGF) levels. RESULTS: Oral administration of the ginger extract resulted in significant reduction of hyperglycemia, the diameter of the retinal vessels, and vascular basement membrane thickness. Improvement in the architecture of the retinal vasculature was associated with significantly reduced expression of NF-κB and reduced activity of TNF-α and VEGF in the retinal tissue in the ginger extract-treated group compared to the vehicle-treated group. CONCLUSIONS: The current study showed that ginger extract containing 5% of 6-gingerol attenuates the retinal microvascular changes in rats with streptozotocin-induced diabetes through anti-inflammatory and antiangiogenic actions. Although precise molecular targets remain to be determined, 6-gingerol seems to be a potential candidate for further investigation.

Plasmalemma Vesicle-Associated Protein Has a Key Role in Blood-Retinal Barrier Loss.

Loss of blood-retinal barrier (BRB) properties induced by vascular endothelial growth factor (VEGF) and other factors is an important cause of diabetic macular edema. Previously, we found that the presence of plasmalemma vesicle-associated protein (PLVAP) in retinal capillaries associates with loss of BRB properties and correlates with increased vascular permeability in diabetic macular edema. In this study, we investigated whether absence of PLVAP protects the BRB from VEGF-induced permeability. We used lentiviral-delivered shRNA or siRNA to inhibit PLVAP expression. The barrier properties of in vitro BRB models were assessed by measuring transendothelial electrical resistance, permeability of differently sized tracers, and the presence of endothelial junction complexes. The effect of VEGF on caveolae formation was studied in human retinal explants. BRB loss in vivo was studied in the mouse oxygen-induced retinopathy model. The inhibition of PLVAP expression resulted in decreased VEGF-induced BRB permeability of fluorescent tracers, both in vivo and in vitro. PLVAP inhibition attenuated transendothelial electrical resistance reduction induced by VEGF in BRB models in vitro and significantly increased transendothelial electrical resistance of the nonbarrier human umbilical vein endothelial cells. Furthermore, PLVAP knockdown prevented VEGF-induced caveolae formation in retinal explants but did not rescue VEGF-induced alterations in endothelial junction complexes. In conclusion, PLVAP is an essential cofactor in VEGF-induced BRB permeability and may become an interesting novel target for diabetic macular edema therapy.

Functional Deficits Precede Structural Lesions in Mice With High-Fat Diet-Induced Diabetic Retinopathy.

Obesity predisposes to human type 2 diabetes, the most common cause of diabetic retinopathy. To determine if high-fat diet-induced diabetes in mice can model retinal disease, we weaned mice to chow or a high-fat diet and tested the hypothesis that diet-induced metabolic disease promotes retinopathy. Compared with controls, mice fed a diet providing 42% of energy as fat developed obesity-related glucose intolerance by 6 months. There was no evidence of microvascular disease until 12 months, when trypsin digests and dye leakage assays showed high fat-fed mice had greater atrophic capillaries, pericyte ghosts, and permeability than controls. However, electroretinographic dysfunction began at 6 months in high fat-fed mice, manifested by increased latencies and reduced amplitudes of oscillatory potentials compared with controls. These electroretinographic abnormalities were correlated with glucose intolerance. Unexpectedly, retinas from high fat-fed mice manifested striking induction of stress kinase and neural inflammasome activation at 3 months, before the development of systemic glucose intolerance, electroretinographic defects, or microvascular disease. These results suggest that retinal disease in the diabetic milieu may progress through inflammatory and neuroretinal stages long before the development of vascular lesions representing the classic hallmark of diabetic retinopathy, establishing a model for assessing novel interventions to treat eye disease.

Effect of aliskiren on vascular remodelling in small retinal circulation.

BACKGROUND: In hypertension, changes in small arterial structure are characterized by an increased wall-to-lumen ratio (WLR). These adaptive processes are modulated by the rennin-angiotensin system. It is unclear whether direct renin inhibitors exert protective effects on small arteries in hypertensive patients. METHODS: In this double-blind, randomized, placebo-controlled study (http://www.clinicaltrials.gov: NCT01318395), 114 patients with primary hypertension were randomized to additional therapy with either placebo or aliskiren 300 mg for 8 weeks after 4 weeks of standardized open-label treatment with valsartan 320 mg (run-in phase). Parameter of arteriolar remodelling was WLR of retinal arterioles (80 - 140 µm) assessed noninvasively and in vivo by scanning laser Doppler flowmetry (Heidelberg Engineering, Germany). In addition, pulse wave analysis (SphygmoCor, AtCor Medical, Australia) and pulse pressure (PP) amplification were determined. RESULTS: In the whole study population, no clear effect of additional therapy with aliskiren on vascular parameters was documented. When analyses were restricted to patients with vascular remodelling, defined by a median of WLR more than 0.3326 (n = 57), WLR was reduced after 8 weeks by the treatment with aliskiren compared with placebo (-0.044 ±â€Š0.07 versus 0.0043 ±â€Š0.07, P = 0.015). Consistently, after 8 weeks of on-top treatment with aliskiren, there was an improvement of PP amplification compared with placebo (0.025 ±â€Š0.07 versus -0.034 ±â€Š0.08, P = 0.013), indicative of less stiff arteries in the peripheral circulation. CONCLUSION: Thus, our data indicate that treatment with aliskiren, given on top of valsartan therapy, improves altered vascular remodelling in hypertensive patients.