Cyclic stretch and hypertension induce retinal expression of vascular endothelial growth factor and vascular endothelial growth factor receptor-2: potential mechanisms for exacerbation of diabetic retinopathy by hypertension

Retinal neurodegeneration in diabetic retinopathy with systemic hypertension

PURPOSE

To identify the impact of hypertension (HTN) on inner retinal layer thickness in patients with diabetic retinopathy (DR).

METHODS

In this retrospective cross-sectional study, participants were divided into three groups: type 2 diabetes patients without DR (DM group), patients with DR (DR group), and patients with both DR and HTN (DR+HTN group). The peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell-inner plexiform layer (GC-IPL) thicknesses, measured using optical coherence tomography, were compared among the groups.

RESULTS

A total of 470 eyes were enrolled: 224 eyes in the DM group, 131 eyes in the DR group, and 115 eyes in the DR+HTN group. The mean RNFL thicknesses were 95.0 ± 7.7, 92.5 ± 10.1, and 89.2 ± 11.2 μm, and the mean GC-IPL thicknesses were 84.0 ± 5.7, 82.0 ± 7.6, and 79.2 ± 8.1 μm in each group, respectively (all P < 0.001). In the DR+HTN group, the DR stage showed a significant association with pRNFL (B = - 5.38, P = 0.014) and GC-IPL (B = - 5.18, P = 0.001) thicknesses in multivariate analyses. Subgroup analyses revealed that pRNFL (P = 0.007) and GC-IPL (P = 0.005) thicknesses decreased significantly as DR progressed only in the DR+HTN group.

CONCLUSIONS

Patients with both DR and HTN exhibited much thinner pRNFL and GC-IPL, compared with patients with DR only. These results may have been related to the amplified diabetic retinal neurodegeneration and synergistic impact of ischemia in DR patients with concurrent HTN. Additionally, the progression of DR resulted in more severe inner retinal damage when combined with HTN.

Chitosan as a promising materials for the construction of nanocarriers for diabetic retinopathy: an updated review

Diabetic retinopathy (DR) is a condition that causes swelling of the blood vessels of the retina and leaks blood and fluids. It is the most severe form of diabetic eye disease. It causes vision loss in its advanced stage. Diabetic retinopathy is responsible for causing 26% of blindness. Very insufficient therapies are accessible for the treatment of DR. As compared to the conventional therapies, there should be enhanced research on the controlled release, shorter duration, and cost-effective therapy of diabetic retinopathy. The expansion of advanced nanocarriers-based drug delivery systems has been now employed to exploit as well as regulate the transport of many therapeutic agents to target sites via the increase in penetration or the extension of the duration of contact employing production by enclosing as well as distributing tiny molecules in nanostructured formulation. Various polymers have been utilized for the manufacturing of these nanostructured formulations. Chitosan possesses incredible biological and chemical properties, that have led to its extensive use in pharmaceutical and biomedical applications. Chitosan has been used in many studies because of its enhanced mucoadhesiveness and non-toxicity. Multiple studies have used chitosan as the best candidate for manufacturing nanocarriers and treating diabetic retinopathy. Numerous nanocarriers have been formulated by using chitosan such as nanostructured lipid carriers, solid lipid nanoparticles, liposomes, and dendrimers for treating diabetic retinopathy. This current review elaborates on the recent advancements of chitosan as a promising approach for the manufacturing of nanocarriers that can be used for treating diabetic retinopathy.

Both New-Onset and Pre-Existing Hypertension Indicate Favorable Clinical Outcomes in Patients Treated With Anti-Vascular Endothelial Growth Factor Therapy

BACKGROUND

Hypertension is a frequent adverse event caused by vascular endothelial growth factor signaling pathway (VSP) inhibitors. However, the impact of hypertension on clinical outcomes during VSP inhibitor therapy remains controversial.Methods and Results: We reviewed 3,460 cancer patients treated with VSP inhibitors from the LIFE Study database, comprising Japanese claims data between 2016 and 2020. Patients were stratified into 3 groups based on the timing of hypertension onset: (1) new-onset hypertension (n=569; hypertension developing after VSP inhibitor administration); (2) pre-existing hypertension (n=1,790); and (3) no hypertension (n=1,101). Time to treatment failure (TTF) was used as the primary endpoint as a surrogate for clinical outcomes. The median (interquartile range) TTF in the new-onset and pre-existing hypertension groups was 301 (133-567) and 170 (72-358) days, respectively, compared with 146 (70-309) days in the non-hypertensive group (P<0.001 among all groups). In an adjusted Cox proportional hazard model, new-onset (hazard ratio [HR] 0.58; 95% confidence interval [CI] 0.50-0.68; P<0.001) and pre-existing (HR 0.85; 95% CI 0.73-0.98; P=0.026) hypertension were independent factors for prolonged TTF. The TTF of new-onset hypertension was longer than that of pre-existing hypertension (HR 0.68; 95% CI 0.62-0.76; P<0.001).

CONCLUSIONS

This study highlighted that new-onset hypertension induced by VSP inhibitors was an independent factor for favorable clinical outcomes. Pre-existing hypertension before VSP inhibitor initiation was also a significant factor.

Changes in peripapillary microvasculature in patients with type 2 diabetes patients: effect of systemic hypertension

To determine the effect of hypertension (HTN) on the peripapillary microvasculature in type 2 diabetes mellitus (T2DM) patients without diabetic retinopathy (DR). The patients were classified into three groups: the control group (group 1), T2DM group (group 2), and both T2DM and HTN group (group 3). Peripapillary vessel density (VD) was compared using analysis of covariance and linear regression analysis was performed to identify the factors affecting the peripapillary VD. A total of 286 eyes were enrolled: 124 in group 1, 111 in group 2, and 51 in group 3. The peripapillary VDs for the full area were 18.3 ± 0.6, 17.8 ± 1.0, and 17.3 ± 1.2 mm-1 in group 1, group 2, and group 3, respectively, which were significantly different after adjustment for age and best-corrected visual acuity (P < 0.001). In post hoc analyses, group 1 versus group 2 (P < 0.001), group 1 versus group 3 (P < 0.001), and group 2 versus group 3 (P = 0.001) showed significant differences. In linear regression analysis, HTN (B =  - 0.352, P = 0.043) and peripapillary retinal nerve fiber layer (pRNFL) thickness (B = 0.045, P < 0.001) were significantly associated with peripapillary VD in T2DM patients. Peripapillary VD in T2DM patients without clinical DR were lower compared to normal controls, and they were more decreased when HTN was comorbid. The combination of ischemic damage by high blood pressure and impairment of the neurovascular unit by hyperglycemia would result in more severe deterioration of peripapillary microvasculature, and this impairment could be also reflected by pRNFL thinning.

A risk prediction model for type 2 diabetes mellitus complicated with retinopathy based on machine learning and its application in health management

Objective

This study aimed to establish a risk prediction model for diabetic retinopathy (DR) in the Chinese type 2 diabetes mellitus (T2DM) population using few inspection indicators and to propose suggestions for chronic disease management.

Methods

This multi-centered retrospective cross-sectional study was conducted among 2,385 patients with T2DM. The predictors of the training set were, respectively, screened by extreme gradient boosting (XGBoost), a random forest recursive feature elimination (RF-RFE) algorithm, a backpropagation neural network (BPNN), and a least absolute shrinkage selection operator (LASSO) model. Model I, a prediction model, was established through multivariable logistic regression analysis based on the predictors repeated ≥3 times in the four screening methods. Logistic regression Model II built on the predictive factors in the previously released DR risk study was introduced into our current study to evaluate the model's effectiveness. Nine evaluation indicators were used to compare the performance of the two prediction models, including the area under the receiver operating characteristic curve (AUROC), accuracy, precision, recall, F1 score, balanced accuracy, calibration curve, Hosmer-Lemeshow test, and Net Reclassification Index (NRI).

Results

When including predictors, such as glycosylated hemoglobin A1c, disease course, postprandial blood glucose, age, systolic blood pressure, and albumin/urine creatinine ratio, multivariable logistic regression Model I demonstrated a better prediction ability than Model II. Model I revealed the highest AUROC (0.703), accuracy (0.796), precision (0.571), recall (0.035), F1 score (0.066), Hosmer-Lemeshow test (0.887), NRI (0.004), and balanced accuracy (0.514).

Conclusion

We have built an accurate DR risk prediction model with fewer indicators for patients with T2DM. It can be used to predict the individualized risk of DR in China effectively. In addition, the model can provide powerful auxiliary technical support for the clinical and health management of patients with diabetes comorbidities.

Identification of the Optimal Model for the Prediction of Diabetic Retinopathy in Chinese Rural Population: Handan Eye Study

BACKGROUND

To identify an optimal model for diabetic retinopathy (DR) prediction in Chinese rural population by establishing and comparing different algorithms based on the data from Handan Eye Study (HES).

METHODS

Five algorithms, including multivariable logistic regression (MLR), classification and regression trees (C&RT), support vector machine (SVM), random forests (RF), and gradient boosting machine (GBM), were used to establish DR prediction models with HES data. The performance of the models was assessed based on the adjusted area under the ROC curve (AUROC), sensitivity, specificity, and accuracy.

RESULTS

The data on 4752 subjects were used to build the DR prediction model, and among them, 198 patients were diagnosed with DR. The age of the included subjects ranged from 30 to 85 years old, with an average age of 50.9 years (SD = 3.04). The kappa coefficient of the diagnosis between the two ophthalmologists was 0.857. The MLR model revealed that blood glucose, systolic blood pressure, and body mass index were independently associated with the development of DR. The AUROC obtained by GBM (0.952), RF (0.949), and MLR (0.936) was similar and statistically larger than that of CART (0.682) and SVM (0.765).

CONCLUSIONS

The MLR model exhibited excellent prediction performance and visible equation and thus was the optimal model for DR prediction. Therefore, the MLR model may have the potential to serve as a complementary screening tool for the early detection of DR, especially in remote and underserved areas.

Fluctuations in Macular Thickness in Patients with Retinal Vein Occlusion Treated with Anti-Vascular Endothelial Growth Factor Agents

PURPOSE

To evaluate macular thickness fluctuations in patients with retinal vein occlusions (RVOs) treated with anti-vascular endothelial growth factor (VEGF) agents and to assess whether patients with larger fluctuations have poorer visual outcomes.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Treatment-naive patients with RVO.

METHODS

Central subfield thickness (CST), cube volume (CV), and cube average thickness (CAT) were collected from OCT images obtained at baseline and 3, 6, 9, and 12 months, and standard deviations (SDs) across 12 months were calculated. Mixed-effects regression was performed to examine the relationship between macular thickness SD and 12-month visual acuity (VA). Standard multiple regression was performed to identify predictors of macular thickness SD.

MAIN OUTCOME MEASURES

Standard deviations across 12 months for CST, CV, and CAT and VA at 12 months.

RESULTS

One hundred thirty-four eyes, including 71 with branch RVO (BRVO) and 63 with central RVO (CRVO), were evaluated. Mean baseline and 12-month CST were 488.6 ± 165.0 μm and 334.3 ± 131.9 μm (change, -154.3 ± 210.2 μm; P < 0.001), with CST SD of 114.1 ± 77.0 μm. Baseline and 12-month VA were 52.8 ± 20.9 letters and 65.9 ± 17.3 letters (change, +13.1 ± 20.3 letters; P < 0.001). Central subfield thickness SD was a significant negative predictor of 12-month VA (-5.21 letters/100 μm; 95% confidence interval [CI], -10.21 to -0.22 letters/100 μm; P = 0.041) when adjusting for baseline factors and injections. Baseline CST and number of injections were not predictive (P ≥ 0.101). Stratification by CST SD demonstrated a 10-letter difference in 12-month VA between the first and fourth quartiles. Baseline CST and RVO diagnosis were the only significant predictors of CST SD (CRVO vs. BRVO: +34.64 μm/100 μm [95% CI, 29.33-39.94 μm/100 μm; P < 0.001] and +22.13 μm/100 μm [95% CI, 4.81-39.44 μm/100 μm; P = 0.013]). Associations using CV and CAT were similar.

CONCLUSIONS

Larger macular thickness fluctuations are associated with poorer visual outcomes in patients with RVO treated with anti-VEGF agents. Macular thickness fluctuations, in addition to absolute macular thickness, may be an important prognostic biomarker in these patients.

Nox (NADPH Oxidase) 1, Nox4, and Nox5 Promote Vascular Permeability and Neovascularization in Retinopathy

Hypertension is a risk factor for the vascular permeability and neovascularization that threatens vision in diabetic retinopathy. Excess reactive oxygen species derived from the Nox (NADPH oxidase) isoforms, Nox1 and Nox4, contributes to vasculopathy in diabetic retinopathy; however, if Nox1/4 inhibition is beneficial in hypertensive diabetic retinopathy is unknown. Here, we determined that diabetic spontaneously hypertensive rats had exacerbated retinal vascular permeability and expression of angiogenic and inflammatory factors, compared with normotensive diabetic Wistar Kyoto rats. GKT136901, a specific dual inhibitor of Nox1 and Nox4, prevented these events in diabetic Wistar Kyoto rats and spontaneously hypertensive rats. Retinal neovascularization does not develop in diabetic rodents, and therefore, the oxygen-induced retinopathy model is used to evaluate this pathology. We previously demonstrated that Nox1/4 inhibition reduced retinal neovascularization in oxygen-induced retinopathy. However, although Nox5 is expressed in human retina, its contribution to retinopathy has not been studied in vivo, largely due to its absence from the rodent genome. We generated transgenic mice with inducible human Nox5 expressed in endothelial cells (vascular endothelial-cadherin⁺Nox5⁺ mice). In vascular endothelial-cadherin⁺Nox5⁺ mice with oxygen-induced retinopathy, retinal vascular permeability and neovascularization, as well as the expression of angiogenic and inflammatory factors, were increased compared with wild-type littermates. In bovine retinal endothelial cells, which express Nox1, Nox4, and Nox5, Nox1/4 inhibition, as well as Nox5 silencing RNA, reduced the high glucose-induced upregulation of oxidative stress, angiogenic, and inflammatory factors. Collectively, these data indicate the potential of Nox1, Nox4, and Nox5 inhibition to reduce vision-threatening damage to the retinal vasculature.

Preeclampsia as predisposing factor for hypertensive retinopathy: Participation by the RAAS and angiogenic factors

Preeclampsia (PE) is a hypertensive complication of pregnancy. Its cause is still unknown and it could be a risk factor for future ophthalmic problems. Retinal vascular bed alterations have been described as a consequence of PE, suggesting a retinopathy. Factors related to angiogenesis and vascular permeability, such as vascular endothelial growth factor (VEGF) and pigment epithelium derived factor (PEDF) or components of the renin angiotensin aldosterone system (RAAS), prorrenin/renin receptor ((P)RR) and angiotensin II type I receptor (AT1R) have been located in the retina, participating in other retinopathies, but it is unknown if they could participate in PE. Our aim was to elucidate whether VEGF, PEDF, (P)RR and AT1R could be modified during PE and during hypertension induced in rats with a history of PE. We used female Wistar rats and subrrenal aortic coarctation to induce PE, and after delivery, we induced a second hit by Nω-nitro-L-arginine methyl ester (L-NAME) administration. We measured blood pressure, proteinuria and pups development. In both models, eye fundal exploration and immunoblot for VEGF, PEDF, (P)RR and AT1R were performed. We found that the development of hypertension occurred faster in previously PE rats than in normal animals. VEGF, PEDF, (P)RR and AT1R were increased in PE, but in L-NAME-induced hypertension only (P)RR and AT1R were altered. Eye fundal data indicated that PE induced a level I retinopathy, but L-NAME induced a faster and more severe retinopathy in previously PE animals compared to previously normal pregnancy rats. These results indicate that PE predisposes to development of a faster and more severe retinopathy after a second hit. They also suggest that VEGF and PEDF seem to participate only in PE retinopathy, but in both models, RAAS components seem to have a more critical participation.

The Schlager mouse as a model of altered retinal phenotype

Hypertension is a risk factor for a large number of vision-threatening eye disorders. In this study, we investigated for the first time the retinal neural structure of the hypertensive BPH/2J mouse (Schlager mouse) and compared it to its control counterpart, the normotensive BPN/3J strain. The BPH/2J mouse is a selectively inbred mouse strain that develops chronic hypertension due to elevated sympathetic nervous system activity. When compared to the BPN/3J strain, the hypertensive BPH/2J mice showed a complete loss of outer layers of the neural retina at 21 weeks of age, which was indicative of a severe vision-threatening disease potentially caused by hypertension. To elucidate whether the retinal neural phenotype in the BPH/2J strain was attributed to increased BP, we investigated the neural retina of both BPN/3J and BPH/2J mice at 4 weeks of age. Our preliminary results showed for the first time that the BPH/2J strain develops severe retinal neural damage at a young age. Our findings suggest that the retinal phenotype in the BPH/2J mouse is possibly due to elevated blood pressure and may be contributed by an early onset spontaneous mutation which is yet to be identified or a congenital defect occurring in this strain. Further characterization of the BPH/2J mouse strain is likely to i) elucidate gene defects underlying retinal disease; ii) understand mechanisms leading to neural retinal disease and iii) permit testing of molecules for translational research to interfere with the progression of retinal disease. The animal experiments were performed with the approval of the Royal Perth Hospital Animal Ethics Committee (R535/17-18) on June 1, 2017.

PHOTOCOAGULATION VERSUS RANIBIZUMAB FOR PROLIFERATIVE DIABETIC RETINOPATHY: Should Baseline Characteristics Affect Choice of Treatment?

PURPOSE

Among eyes with proliferative diabetic retinopathy, identify whether baseline characteristics impact the benefit of ranibizumab over panretinal photocoagulation (PRP) in DRCR.net Protocol S.

METHODS

Participants had proliferative diabetic retinopathy, visual acuity of 20/320 or better, and no previous PRP. Eyes were randomized to PRP or intravitreous 0.5-mg ranibizumab.

RESULTS

Ranibizumab was superior to PRP for change in visual acuity and development of vision-impairing central-involved diabetic macular edema over 2 years (P < 0.001). Among 25 characteristics, there were none in which participants assigned to PRP had superior outcomes relative to ranibizumab-assigned participants. The relative benefit of ranibizumab over PRP for change in visual acuity seemed greater in participants with higher mean arterial pressure (P = 0.03), without previous focal/grid laser (P = 0.03), with neovascularization of the disk and elsewhere on clinical examination (P = 0.04), and with more advanced proliferative diabetic retinopathy on photographs (P = 0.02). For development of vision-impairing central-involved diabetic macular edema, the relative benefit of ranibizumab over PRP seemed greater among nonwhite participants (P = 0.01) and those with higher mean arterial pressure (P = 0.01).

CONCLUSION

There were no characteristics identified in which outcomes were superior with PRP compared with ranibizumab. These exploratory analyses provide additional support that ranibizumab may be a reasonable alternative to PRP for proliferative diabetic retinopathy over a 2-year period.

Optical coherence tomography angiography analysis of the choriocapillary layer in treatment-naïve diabetic eyes

PURPOSE

To evaluate the capillary flow density (CFD) of choriocapillary (CC) microvasculature using optical coherence tomography angiography (OCT-A) in diabetic eyes and the association of CFD and systemic and metabolic factors.

METHODS

Cross-sectional study. This study enrolled 282 eyes of 146 subjects, including 43 healthy control eyes, 56 diabetic eyes without diabetic retinopathy (DR), 43 eyes with mild nonproliferative DR (NPDR), 54 eyes with moderate NPDR, 38 eyes with severe NPDR, and 48 eyes with proliferative DR (PDR). CFD was measured in the CC layer. Clinical data were collected. Multiple linear regression analyses were performed to identify associated clinical variables.

RESULTS

CFD in the CC layer presented a downward trend with DR progression. Comparisons of CFD in the CC layer between adjacent stages of DR revealed significant differences between severe NPDR and PDR using both 3-mm and 6-mm scan patterns (P = 0.003, P = 0.001). CFD in the CC layer in DR with diabetic macular edema (DME) was less than that in DR without DME using both 3-mm and 6-mm scan patterns (P < 0.001, P < 0.001). Coronary artery disease and atherosclerosis in other locations, estimated glomerular filtration rate, and increased HbA1c were associated with CFD in the CC layer using both 3-mm and 6-mm scan patterns (all P values < 0.05).

CONCLUSIONS

OCT-A revealed decreased CFD in the CC layer in the PDR stage and the presence of DME. Diabetic patients with apparently decreased CFD should be assessed carefully under general conditions.

Risk factors for retinal microvascular impairment in type 2 diabetic patients without diabetic retinopathy

Objectives

To determine the risk factors for retinal microvascular impairment on optical coherence tomography angiography (OCT-A) in type 2 diabetic patients without clinical diabetic retinopathy (DR).

Methods

This retrospective and cross-sectional study enrolled 74 diabetic patients without clinically evident DR for the study group and 34 healthy subjects for the control group. OCT-A parameters were measured to determine vascular density (VD) and the foveal avascular zone (FAZ) size in the superficial and deep capillary plexuses (SCP/DCP) of the retina. Clinical data were collected on sex, age, diabetes duration, hemoglobin A1c (HbA1c), hypertension, dyslipidemia, low-density lipoprotein cholesterol (LDL-C), estimated glomerular filtration rate (eGFR) and smoking status. Multiple linear regression analyses were performed to represent the associated clinical variables with OCT-A parameters in diabetic patients.

Results

In comparison between the study and control groups, the VD in the SCP and DCP were significantly lower in diabetic patients compared to the controls (P = 0.022 and 0.003, respectively). The FAZ size in the SCP and DCP were significantly greater in diabetic patients compared to the controls (P = 0.035 and <0.001, respectively). In age- and sex-adjusted multiple regression analyses for the diabetic patients, dyslipidemia and hypertension were negatively associated with SCP-VD (β = -0.357, P = 0.002; β = -0.239, P = 0.039, respectively). Current smoking was correlated with lower DCP-VD (β = -0.255, P = 0.043). Greater SCP-FAZ size was associated with dyslipidemia and greater LDL-C (β = 0.254, P = 0.013; β = 0.232, P = 0.029, respectively), and greater DCP-FAZ size, with lower eGFR and greater LDL-C (β = -0.355, P = 0.004; β = 0.235, P = 0.037, respectively).

Conclusions

Diabetic patients without clinical DR showed lower VD and greater FAZ size in the SCP and DCP compared to healthy controls. In diabetic patients without clinical DR, dyslipidemia and/or high LDL-C were important risk factors for retinal microvascular impairment. Hypertension, current smoking and lower eGFR also contributed to microvascular impairment.

Treatment of intravitreal bevacizumab combined with focal laser photocoagulation in the case of macular telangiectasia type 2 with retinal arterial macroaneurysm

Macular telangiectasia type 2 (Mac Tel 2) is a bilateral disease of unknown cause with characteristic changes of the retinal vasculature. To the best of our knowledge, we could not find any reported cases of Mac Tel 2 with retinal arterial macroaneurysm (RAM). Our aim is to report a case of Mac Tel 2 with RAM.

Treatment of intravitreal bevacizumab combined with focal laser photocoagulation in the case of macular telangiectasia type 2 with retinal arterial macroaneurysm

Macular telangiectasia type 2 (Mac Tel 2) is a bilateral disease of unknown cause with characteristic changes of the retinal vasculature. To the best of our knowledge, we could not find any reported cases of Mac Tel 2 with retinal arterial macroaneurysm (RAM). Our aim is to report a case of Mac Tel 2 with RAM.

Expression of vascular endothelial growth factor in cardiac repair: Signaling mechanisms mediating vascular protective effects

The present study was aimed to investigate the vascular endothelial growth factor expression pattern in acute myocardial infarction induced rats. Serum level of vascular endothelial growth factor and its mRNA expression in myocardium were determined. Protein expression of vascular endothelial growth factor and endothelial nitric oxide synthase were measured. Serum level of vascular endothelial growth factor was increased 105.3, 260, 378.2 and 271.3% following the onset of acute myocardial infarction at 3, 6, 9 and 12days respectively. The mRNA and protein expression of vascular endothelial growth factor was substantially increased following the onset of acute myocardial infarction. Protein expression of endothelial nitric oxide synthase was increased up to 1.02 fold. Taking all these data together, it is concluded that the vascular endothelial growth factor was increased in serum and tissue and attained peak at 9th day following the onset of acute myocardial infarction. Increased vascular endothelial growth factor level in serum and tissue could increase endothelial cell proliferation and angiogenesis, and endothelial nitric oxide synthase could inhibit apoptosis and protect cardiomyocytes. In conclusion, the increased vascular endothelial growth factor expression could play an essential role in cardiac repair following the onset of acute myocardial infarction.

Plasma N-Terminal Probrain Natriuretic Peptide, Vascular Endothelial Growth Factor, and Cardiac Troponin I as Novel Biomarkers of Hypertensive Disease and Target Organ Damage in Cats

Background

In the absence of ocular target organ damage (ocular‐TOD), diagnosis of hypertension is challenging in cats. Biomarkers would provide additional support for the diagnosis of hypertension.

Hypothesis

Vascular endothelial growth factor (VEGF), N‐terminal probrain natriuretic peptide (NT‐proBNP), cardiac troponin I (cTnI), and urine protein‐to‐creatinine ratio (UPC) are predictors of systemic hypertension, will be increased in cats with hypertension with or without ocular‐TOD, and will decrease with antihypertensive treatment.

Methods

Plasma VEGF, NT‐proBNP, and cTnI concentrations and UPC were determined in healthy geriatric cats, normotensive cats with chronic kidney disease (CKD), hypertensive cats with evidence of hypertensive retinopathy (HT‐ocular‐TOD), and hypertensive cats without hypertensive ocular‐TOD (HT‐noTOD). Comparisons among groups were performed. Multivariable binary logistic regression models were built to identify independent biomarkers of hypertension and ocular‐TOD. Receiver operator characteristic (ROC) curves were drawn to assess clinical use.

Results

Cats with HT‐ocular‐TOD had significantly higher VEGF than all other groups (P < .05) and significantly higher NT‐proBNP than healthy cats (P < .001). Healthy cats had significantly lower cTnI than all other groups (P < .05). No differences were found among groups for UPC (P = .08). Cardiac troponin I and VEGF were independent predictors of hypertension (P < .05), but none of the biomarkers were independent predictors of ocular‐TOD. N‐terminal probrain natriuretic peptide concentrations decreased with antihypertensive treatment (P < .001). The ROC curves indicated that none of the biomarkers met the criteria to function as diagnostic tests for the diagnosis of hypertension or associated ocular‐TOD.

Conclusions and Clinical Significance

Despite statistical significance and changes with ocular‐TOD, antihypertensive treatment, or both, VEGF, NT‐proBNP, and cTnI did not function as useful diagnostic tests for hypertension. Persistently increased systolic blood pressure (SBP) measurements in combination with fundoscopy remains the preferred method for diagnosis of feline hypertension.

Retinal vascular and structural changes are associated with amyloid burden in the elderly: ophthalmic biomarkers of preclinical Alzheimer's disease

BACKGROUND

Retinal imaging may serve as an alternative approach to monitor brain pathology in Alzheimer's disease (AD). In this study, we investigated the association between retinal vascular and structural changes and cerebral amyloid-β (Aβ) plaque load in an elderly cohort.

METHODS

We studied a total of 101 participants, including 73 elderly subjects (79 ± 5 years, 22 male) with no clinical diagnosis of AD but reporting some subjective memory change and an additional 28 subjects (70 ± 9 years, 16 male) with clinically established AD. Following a complete dilated ocular examination, the amplitude of retinal vascular pulsations and dynamic response, retinal nerve fibre layer thickness and retinal ganglion cell layer (RGCL) thickness were determined in all patients. Systemic blood pressure and carotid-to-femoral pulse wave velocity were measured. The elderly cohort also underwent magnetic resonance imaging and ¹⁸F-florbetaben (FBB)-positron emission tomographic amyloid imaging to measure neocortical Aβ standardised uptake value ratio (SUVR), and this was used to characterise a 'preclinical' group (SUVR >1.4).

RESULTS

The mean FBB neocortical SUVR was 1.35 ± 0.3. The amplitude of retinal venous pulsations correlated negatively with the neocortical Aβ scores (p < 0.001), whereas the amplitude of retinal arterial pulsations correlated positively with neocortical Aβ scores (p < 0.01). RGCL thickness was significantly lower in the clinical AD group (p < 0.05).

CONCLUSIONS

The correlation between retinal vascular changes and Aβ plaque load supports the possibility of a vascular component to AD. Dynamic retinal vascular parameters may provide an additional inexpensive tool to aid in the preclinical assessment of AD.

Endothelial cell signaling and ventilator-induced lung injury: molecular mechanisms, genomic analyses, and therapeutic targets

Mechanical ventilation is a life-saving intervention in critically ill patients with respiratory failure due to acute respiratory distress syndrome (ARDS). Paradoxically, mechanical ventilation also creates excessive mechanical stress that directly augments lung injury, a syndrome known as ventilator-induced lung injury (VILI). The pathobiology of VILI and ARDS shares many inflammatory features including increases in lung vascular permeability due to loss of endothelial cell barrier integrity resulting in alveolar flooding. While there have been advances in the understanding of certain elements of VILI and ARDS pathobiology, such as defining the importance of lung inflammatory leukocyte infiltration and highly induced cytokine expression, a deep understanding of the initiating and regulatory pathways involved in these inflammatory responses remains poorly understood. Prevailing evidence indicates that loss of endothelial barrier function plays a primary role in the development of VILI and ARDS. Thus this review will focus on the latest knowledge related to 1) the key role of the endothelium in the pathogenesis of VILI; 2) the transcription factors that relay the effects of excessive mechanical stress in the endothelium; 3) the mechanical stress-induced posttranslational modifications that influence key signaling pathways involved in VILI responses in the endothelium; 4) the genetic and epigenetic regulation of key target genes in the endothelium that are involved in VILI responses; and 5) the need for novel therapeutic strategies for VILI that can preserve endothelial barrier function.

Static mechanical strain induces capillary endothelial cell cycle re-entry and sprouting

Vascular endothelial cells are known to respond to a range of biochemical and time-varying mechanical cues that can promote blood vessel sprouting termed angiogenesis. It is less understood how these cells respond to sustained (i.e., static) mechanical cues such as the deformation generated by other contractile vascular cells, cues which can change with age and disease state. Here we demonstrate that static tensile strain of 10%, consistent with that exerted by contractile microvascular pericytes, can directly and rapidly induce cell cycle re-entry in growth-arrested microvascular endothelial cell monolayers. S-phase entry in response to this strain correlates with absence of nuclear p27, a cyclin-dependent kinase inhibitor. Furthermore, this modest strain promotes sprouting of endothelial cells, suggesting a novel mechanical 'angiogenic switch'. These findings suggest that static tensile strain can directly stimulate pathological angiogenesis, implying that pericyte absence or death is not necessarily required of endothelial cell re-activation.

From the analysis of pharmacologic vitreolysis to the comprehension of ocriplasmin safety

INTRODUCTION

Pharmacologic vitreolysis is a strategy used to treat anomalous posterior vitreous detachment, by weakening vitreoretinal adhesion with an intravitreal drug. Pharmacologic vitreolysis facilitates surgery, and abnormalities of the vitreoretinal interface including vitreomacular traction (VMT) and early stage macular hole (MH) could be resolved. Ocriplasmin is a recombinant protease, active against fibronectin and laminin, which are important components of the vitreoretinal interface. Ocriplasmin has been approved for symptomatic treatment of VMT and MH with visible traction, and it functions by dissolving the proteins that link the vitreous to the macula, thereby creating a complete posterior vitreous detachment (PVD).

AREAS COVERED

This paper reviews the current knowledge and status of investigations regarding the use of ocriplasmin for pharmacologic vitreolysis and its safety.

EXPERT OPINION

Ocriplasmin is a non-specific enzyme; therefore, it dissolves vitreal proteins as well as possibly proteins associated with visual function in the retina, choroid, and lens. Ocular adverse events (OAEs) of ocriplasmin include transient visual loss, intraocular inflammation, vitreous floaters, lens opacification, zonular instability of the lens, and intraocular hemorrhage. The prevalence of the OAEs is very low; however, on rare occasions, they can result in widespread retinal dysfunction. Research into the acute and long-term safety of ocriplasmin is required.

Pharmacologic Vitreolysis in Vascular Diseases of the Retina

Vascular diseases of the retina such as diabetic retinopathy and vascular occlusions account for a large proportion of visual morbidity and blindness worldwide. The role of vitreous in the pathogenesis of these conditions has been increasingly recognized. Despite advances in the surgical technique of pars plana vitrectomy, the use of intravitreal agents for the lysis of vitreous has received attention, guided largely by promising results from the trials involving patients with non-vascular retinal diseases such as vitreomacular traction. The purpose of this review is to provide a comprehensive summary of the present knowledge on pathophysiologic basis of pharmacologic vitreolysis and its efficacy in vascular diseases of the retina. A review of completed and ongoing clinical trials will be presented, along with insights into future directions of this therapy.

Effects of Vitreomacular Adhesion on Age-Related Macular Degeneration

Herein, we review the association between vitreomacular adhesion (VMA) and neovascular age-related macular degeneration (AMD). Meta-analyses have shown that eyes with neovascular AMD are twice as likely to have VMA as normal eyes. VMA in neovascular AMD may induce inflammation, macular traction, decrease in oxygenation, sequestering of vascular endothelial growth factor (VEGF), and other cytokines or may directly stimulate VEGF production. VMA may also interfere with the treatment effects of anti-VEGF therapy, which is the standard treatment for neovascular AMD, and releasing VMA can improve the treatment response to anti-VEGF treatment in neovascular AMD. We also reviewed currently available methods of relieving VMA.

Idiopathic Macular Telangiectasia Type 1 with Ruptured Retinal Arterial Macroaneurysm Post Intravitreal Bevacizumab

A 50-year-old Indian male presented with defective vision in the right eye for 6 months. He was diagnosed to have idiopathic macular telangiectasia (IMT) type 1 associated with diffuse macular edema and multiple retinal arterial macroaneurysms (RAM). Intravitreal bevacizumab was administered for the treatment of macular edema, following which there was a rupture of a preexisting RAM with multilevel retinal hemorrhages. The hemorrhage gradually resolved over time with foveal thinning noted at last visit. We report this case for the rare occurrence of IMT type 1 and also the possibly associated rupture of RAM post intravitreal bevacizumab injection.

Regulation of thrombomodulin expression and release in human aortic endothelial cells by cyclic strain

Background and Objectives

Thrombomodulin (TM), an integral membrane glycoprotein expressed on the lumenal surface of vascular endothelial cells, promotes anti-coagulant and anti-inflammatory properties. Release of functional TM from the endothelium surface into plasma has also been reported. Much is still unknown however about how endothelial TM is regulated by physiologic hemodynamic forces (and particularly cyclic strain) intrinsic to endothelial-mediated vascular homeostasis.

Methods

This study employed human aortic endothelial cells (HAECs) to investigate the effects of equibiaxial cyclic strain (7.5%, 60 cycles/min, 24 hrs), and to a lesser extent, laminar shear stress (10 dynes/cm², 24 hrs), on TM expression and release. Time-, dose- and frequency-dependency studies were performed.

Results

Our initial studies demonstrated that cyclic strain strongly downregulated TM expression in a p38- and receptor tyrosine kinase-dependent manner. This was in contrast to the upregulatory effect of shear stress. Moreover, both forces significantly upregulated TM release over a 48 hr period. With continuing focus on the cyclic strain-induced TM release, we noted both dose (0–7.5%) and frequency (0.5–2.0 Hz) dependency, with no attenuation of strain-induced TM release observed following inhibition of MAP kinases (p38, ERK-1/2), receptor tyrosine kinase, or eNOS. The concerted impact of cyclic strain and inflammatory mediators on TM release from HAECs was also investigated. In this respect, both TNFα (100 ng/ml) and ox-LDL (10–50 µg/ml) appeared to potentiate strain-induced TM release. Finally, inhibition of neither MMPs (GM6001) nor rhomboids (3,4-dichloroisocoumarin) had any effect on strain-induced TM release. However, significantly elevated levels (2.1 fold) of TM were observed in isolated microparticle fractions following 7.5% strain for 24 hrs.

Conclusions

A preliminary in vitro investigation into the effects of cyclic strain on TM in HAECs is presented. Physiologic cyclic strain was observed to downregulate TM expression, whilst upregulating in a time-, dose- and frequency-dependent manner the release of TM.

The performance of a diabetic retinopathy risk score for screening for diabetic retinopathy in Chinese overweight/obese patients with type 2 diabetes mellitus

INTRODUCTION

Diabetic retinopathy (DR) is a common chronic microvascular diabetic complication. The presence of DR may indicate microcirculatory dysfunction in other organ systems besides visual morbidity. The objective of this study was to develop a simple diabetic retinopathy risk score to identify DR in Chinese overweight/obese patients with type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

A multicentre hospital-based cross-sectional study was carried out in Guangdong Province between August 2011 and March 2012. The evaluated 2699 patients included 1263 males and 1436 females, with an average age of 59.4 ± 13.0 years.

RESULTS

The diabetic retinopathy risk score was conducted by age, duration of DM, history of antihypertensive drug treatment, and waist circumference. The area under the receiver operating characteristics curve for DR was 0.700 (95% CI 0.671-0.729). Comparing Youden's index of different values, the optimal cut-off point was 20 to predict DR. The odds ratio for one unit increase in the diabetic retinopathy risk score associated with the risk of DR was 1.104 (95% CI 1.089-1.120).

CONCLUSIONS

Our data suggest that the diabetic retinopathy risk score could be a reliable primary screening tool for the presence of DR in Chinese overweight/obese patients with T2DM.

Extract of Litsea japonica ameliorates blood-retinal barrier breakdown in db/db mice

Loss of blood-retinal barrier (BRB) properties is an important feature in the pathology of diabetic retinopathy. Endothelium integrity is important for the normal vascular function. Litsea japonica (Thunb.) Jussieu is a Korean native plant that is consumed as a vegetable food. In this study, we evaluated the ability of an ethanol extract of L. japonica to prevent retinal vascular leakages in db/db mice, which is an animal model of type II diabetes. L. japonica extracts (LJE, 100 and 250 mg/kg) were administered once a day, orally, for 12 weeks. Vehicle-treated db/db mice exhibited hyperglycemia and retinal vascular leakage. LJE treatment blocked diabetes-induced BRB breakdown and decreased retinal VEGF expression in db/db mice. LJE also inhibited the degradation of occludin, which is an important tight junction protein. These findings support the potential therapeutic usefulness of L. japonica for retinal vascular permeability diseases.

Predictors of diabetic retinopathy in patients with type 2 diabetes who have normoalbuminuria

Background:

Microalbuminuria is an independent predictor of retinopathy, so absence of microalbuminuria may tend clinician not to screen for diabetic retinopathy (DR).

Aim:

The aim of our study was to estimate prevalence of DR in patients with type 2 diabetes who have normoalbuminuria, and to study predictors for DR, which can identify these high-risk individuals.

Subjects and Methods:

In a prospective cross-sectional study that included patients with type 2 DM and normoalbuminuria. Diagnosis of DR was made by a trained ophthalmologist based on the presence of clinical features in the fundus of both eyes following the International Clinical DR guidelines. The statistical analyses were performed using Statistical Package for the Social Sciences 15.0 version software (Chicago, IL, USA). The continuous variables expressed as means (SD and Student's t-test or Mann–Whitney test were used, as appropriate, to determine differences in them. Categorical variables were presented as percentage. The Pearson's Chi-square test or Fisher's exact test, as appropriate, was used to determine the differences in them.

Results:

A total of 226 patients with type 2 DM and normoalbuminuria were enrolled in the study that included 110 males (48.6%), and 116 females (51.4%) Mean (SD) duration of diabetes was 8.2 (5.6) years. DR of any grade was present in 49/226 (22%) patients. Of the patients with DR of any grade, 31/49 (63%) had mild non-proliferative diabetic retinopathy (NPDR) 10/49 (22%) had moderate to severe NPDR and 8/49 (15%) had PDR. Duration of diabetes (OR 1.01, 95% CI, 0.86-2.2, P = 0.04), higher systolic blood pressure (OR 2.2, 95% CI, 1.6-4.5, P = 0.01), low hemoglobin (OR 1.4, 95% CI, 0.45-2.9, P = 0.01), and a higher tertile of urinary albumin excretion rate (OR 4.12, 95% CI, 1.92-7.57, P = 0.001) had independently significant association with DR.

Conclusion:

The risk of DR exists in patients with type 2 diabetes even in normoalbuminuric individuals. Close monitoring is particularly needed if patients have longer duration of diabetes, hypertension, anemia, or high normal albuminuria.

Mechanical stretching induces matrix metalloproteinase-2 expression in rat retinal glial (Müller) cells

Pathological myopia, as one of the leading causes of blindness, is characterized by excessive and progressive elongation of the eyeball with concomitant degenerative changes in the posterior segment of the eye. During the progressive distension of the posterior pole, the retina, choroid, and sclera are subjected to constant mechanical force, as a result of which, tissue remodeling occurs. Active remodeling of the sclera in myopia has been studied intensively. By comparison, retinal remodeling under mechanical stretching has attracted little attention, and further research is therefore required. In this study, we showed that constant mechanical stretching of rat retinal Müller cells for 24 h led to a significant increase in the intracellular matrix metalloproteinase-2 mRNA and protein levels. The extracellular secretory matrix metalloproteinase-2 protein levels and activity were also enhanced. These results suggest a possible novel molecular mechanism that would account for retinal remodeling in many ocular diseases in which the retina is often overstretched, such as pathological myopia and proliferative vitreoretinopathy.

Gene expression changes under cyclic mechanical stretching in rat retinal glial (Müller) cells

Objective

The retina is subjected to tractional forces in various conditions. As the predominant glial element in the retina, Müller cells are active players in all forms of retinal injury and disease. In this study, we aim to identify patterns of gene expression changes induced by cyclic mechanical stretching in Müller cells.

Methods

Rat Müller cells were seeded onto flexible bottom culture plates and subjected to a cyclic stretching regimen of 15% equibiaxial stretching for 1 and 24 h. RNA was extracted and amplified, labeled, and hybridized to rat genome microarrays. The expression profiles were analyzed using GeneSpring software, and gene ontology analysis and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to select, annotate, and visualize genes by function and pathway. The selected genes of interest were further validated by Quantitative Real-time PCR (qPCR).

Results

Microarray data analysis showed that at 1 and 24 h, the expression of 532 and 991 genes in the Müller cells significantly (t-test, p<0.05) differed between the mechanically stretched and unstretched groups. Of these genes, 56 genes at 1 h and 62 genes at 24 h showed more than a twofold change in expression. Several genes related to response to stimulus (e.g., Egr2, IL6), cell proliferation (e.g., Areg, Atf3), tissue remodeling (e.g., PVR, Loxl2), and vasculogenesis (e.g., Epha2, Nrn1) were selected and validated by qPCR. KEGG pathway analysis showed significant changes in MAPK signaling at both time points.

Conclusions

Cyclic mechanical strain induces extensive changes in the gene expression in Müller cells through multiple molecular pathways. These results indicate the complex mechanoresponsive nature of Müller cells, and they provide novel insights into possible molecular mechanisms that would account for many retinal diseases in which the retina is often subjected to mechanical forces, such as pathological myopia and proliferative vitreoretinopathy.

Retinopathy in diabetes

With the incidence, and prevalence of diabetes mellitus increasing worldwide, diabetic retinopathy is expected to reach epidemic proportions. The aim of this chapter is to introduce diabetic retinopathy, a leading cause of blindness in people of the working age. The clinical course of retinopathy, anatomical changes, its pathogenesis and current treatment are described, followed by an overview of the emerging drug therapies for the potential treatment of this sight-threatening complication of diabetes.

Fluid pressure is a magnitude-dependent modulator of early endothelial tubulogenic activity: implications related to a potential tissue-engineering control parameter

A significant barrier to the success of engineered tissues is the inadequate transport of nutrients and gases to, and waste away from, cells within the constructs, after implantation. Generation of microtubular networks by endothelial cells in engineered constructs to mimic the in vivo transport scheme is essential for facilitating tissue survival by promoting the in vitro formation of microvessels that integrate with host microvasculature, after implantation. Previously, we reported that select pressures stimulate endothelial proliferation involving protubulogenic molecules such as fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor-C (VEGF-C). Based on this, we investigated fluid pressure as a selective modulator of early tubulogenic activity with the intent of assessing the potential utility of this mechanical stimulus as a tissue-engineering control parameter. For this purpose, we used a custom pressure system to expose two-dimensional (2D) and three-dimensional (3D) cultures of endothelial cells to static pressures of 0 (controls), 20, or 40 mmHg for 3 days. Compared to controls, 2D endothelial cultures exposed to 20, but not 40 mmHg, exhibited significantly (p<0.05) enhanced cell growth that depended on VEGF receptor-3 (VEGFR-3), a receptor for VEGF-C. Moreover, endothelial cells grown on microbeads and suspended in 3D collagen gels under 20 mmHg, but not 40 mmHg, displayed significantly (p<0.05) increased sprout formation. Interestingly, pressure-dependent proliferation and sprout formation occurred in parallel with pressure-sensitive upregulation of VEGF-C and VEGFR-3 expression and were sensitive to local FGF-2 levels. Collectively, the results of the present study provided evidence that early endothelial-related tubulogenic activity depends on local hydrostatic pressure levels in the context of local growth factor conditions. In addition to relevance to microvascular diseases associated with interstitial hypertension (e.g., cancer and glaucoma), these findings provided first insight into the potential utility of hydrostatic pressure as a fine-tune control parameter to optimize microvascularization of tissue-engineering constructs in the in vitro setting before their implantation.

Increases of vitreous monocyte chemotactic protein 1 and interleukin 8 levels in patients with concurrent hypertension and diabetic retinopathy

PURPOSE

To investigate whether concurrent hypertension affects vitreous cytokine levels in diabetic retinopathy.

METHODS

Vitreous samples from 41 patients with diabetic retinopathy with or without concurrent hypertension, who underwent vitrectomy, were collected. Vitreous cytokine concentrations were simultaneously measured using flow cytometry. Patients were stratified according to hypertension or other clinical conditions, and the differences in vitreous levels of monocyte chemotactic protein 1, interleukin 8, vascular endothelial growth factor, interferon-inducible protein 10, and monokine induced by interferon gamma were examined.

RESULTS

Vitreous levels of monocyte chemotactic protein 1 and interleukin 8 were significantly (P < 0.05) higher in hypertensive patients than in nonhypertensive patients and were significantly (P < 0.05) higher in active diabetic retinopathy than in inactive diabetic retinopathy. Vitreous levels of vascular endothelial growth factor, interferon-inducible protein 10, and monokine induced by interferon gamma were not affected by the coexistence of hypertension. In multivariate models, active diabetic retinopathy (P = 0.004 and P = 0.007), systolic blood pressure (P = 0.039 and P = 0.041), and hypertension (P = 0.032 and P = 0.035) were significant and independent predictors for increased vitreous monocyte chemotactic protein 1 and interleukin 8 levels.

CONCLUSION

Both monocyte chemotactic protein 1 and interleukin 8 levels were elevated in the vitreous of patients with diabetic retinopathy and concurrent hypertension. These findings may help to explain the epidemiologic and clinical evidence that systemic hypertension exacerbates diabetic retinopathy.

Role of shear-stress-induced VEGF expression in endothelial cell survival

Vascular endothelial growth factor (VEGF) plays a crucial role in developmental and pathological angiogenesis. Expression of VEGF in quiescent adult tissue suggests a potential role in the maintenance of mature blood vessels. We demonstrate, using a Vegf-lacZ reporter mouse model, that VEGF is expressed by arterial but not by venous or capillary endothelial cells (ECs) in vivo. Using an in vitro model, we show that arterial shear stress of human umbilical vein ECs (HUVECs) decreases apoptosis and increases VEGF expression, which is mediated by the induction of Krüppel-like factor 2 (KLF2). Additionally, shear stress stimulates the expression of VEGF receptor 2 (VEGFR2) and is associated with its activation. Knockdown of VEGF in shear stressed HUVECs blocks the protective effect of shear stress, resulting in EC apoptosis equivalent to that in control ECs cultured under static conditions. Similarly, treatment of ECs subjected to arterial shear stress with the VEGF receptor tyrosine kinase inhibitor SU1498, or VEGFR2 neutralizing antiserum, led to increased apoptosis, demonstrating that the mechanoprotection from increased shear is mediated by VEGFR2. Taken together, these studies suggest that arterial flow induces VEGF-VEGFR2 autocrine-juxtacrine signaling, which is a previously unidentified mechanism for vascular EC survival in adult arterial blood vessels.

Resveratrol blocks diabetes-induced early vascular lesions and vascular endothelial growth factor induction in mouse retinas

PURPOSE

Vessel leakage and loss of pericytes are early signs of diabetic retinopathy (DR), which leads to vision loss. Upregulation of the vascular endothelial growth factor (VEGF) during diabetes plays a key role in mediating these vascular lesions. The aim of this study is to investigate the effects of resveratrol, a natural plant-derived phytoalexin, on vascular damage and VEGF induction in mouse retinas of early diabetes.

METHODS

Diabetes was induced in C57BL/6 mice by five consecutive-intraperitoneal injections of 55 mg/kg of streptozotocin (STZ). Animals injected with buffer only were used as controls. Beginning 1 month after the fifth injection of STZ or buffer, 20 mg/kg of resveratrol was administered by oral gavage daily for 4 weeks to diabetic and control mice, and all mice were killed 2 months after the injections. We assessed vessel leakage, pericyte loss and VEGF protein expression in mouse retinas of 2-month diabetes compared with controls with or without resveratrol treatment.

RESULTS

Diabetes led to increase vessel leakage, pericyte loss and VEGF protein level in the mouse retinas compared with controls; however, these changes were effectively blocked by resveratrol treatment.

CONCLUSION

Our data suggest that resveratrol is effective to decrease vascular lesions and VEGF induction in mouse retinas of early diabetes.

Factors associated with diabetic retinopathy in chinese patients with type 2 diabetes mellitus

Objective. To investigate the risk factors of DR in Chinese T2DM patients. Methods. 2009 patients with T2DM were included in this cross-sectional study. All patients underwent eye examination, and the DR stage was defined by an ophthalmologist. Correlation analysis was performed to evaluate the relation between DR and clinical variables. Logistic regression models were used to assess risk for those factors associated with DR. Results. A total of 597 T2DM patients (29.7%) had DR, of which 548 (27.3%) were nonproliferative diabetic retinopathy and 49 (2.4%) were proliferative diabetic retinopathy. Positive correlations were found between DR and duration of diabetes, systolic blood pressure (SBP), diastolic blood pressure, glycated hemoglobin, glycated albumin, 24 hurinary albumin excretion, peripheral atherosclerosis (PA), diabetes nephropathy (DN), diabetic peripheral neuropathy, and anemia. Negative correlations were found between DR and C-peptide and glomerular filtration rate. Logistic regression analysis revealed that duration of diabetes, SBP, DN, anemia, PA, and C-peptide were each independent risk factors of DR. Conclusion. The duration of diabetes, SBP, DN, anemia, and PA are positively associated with DR in Chinese T2DM patients, while C-peptide is negatively associated with DR. Monitoring and evaluation of these related factors will likely contribute to the prevention and treatment of DR.

The use of bevacizumab in a multilevel retinal hemorrhage secondary to retinal macroaneurysm: a 39-month follow-up case report

Purpose

The evaluation of long-term visual outcome after the use of bevacizumab for the management of multilevel hemorrhage due to retinal arterial macroaneurysm (MA).

Case report

A 71-year-old hypertensive female presented with sudden reduction of visual acuity in her left eye (OS). Fundoscopy revealed an arterial macroaneurysm with preretinal and subretinal hemorrhage in the eye. Due to significant macular involvement, the patient received two intravitreal injections of bevacizumab within 2 months.

Results

Significant visual and anatomical recovery was observed 2 months later, which was confirmed by fluorescein angiography. At the end of a follow-up period (39 months) visual acuity and visual field were at normal levels.

Conclusion

Retinal MA is a relatively rare condition. Anti-vascular endothelial growth factor therapy appears a safe and effective treatment option for selected symptomatic individuals that may offer faster visual rehabilitation. Herein we report, for the first time, a 39-month follow-up of a retinal MA treated with anti-vascular endothelial growth factor therapy.

Diabetic retinopathy - An update

Management of diabetes should involve both systemic and ocular aspects. Control of hyperglycemia, hypertension and dyslipidemia are of major role in the management of diabetic retinopathy. In the ocular part; laser treatment remains the cornerstone of treatment of diabetic macular edema (focal/grid), severe non-proliferative and proliferative diabetic retinopathy (panretinal photocoagulation). There is a strong support to combination therapy. Using one or two intravitreal injections such as anti-VEGF and or steroid to reduce central macular thickness followed by focal or grid laser to give a sustained response may offer an alternative to treatment in diabetic macular edema. Anti-VEGF were found to be effective as an adjunct therapy in proliferative diabetic retinopathy patient who is going to have vitrectomy for vitreous hemorrhage with neovascularization, panretinal photocoagulation, and other ocular surgery such as cases with neovascular glaucoma and cataract with refractory macular edema.

The contribution of hypertension to diabetic nephropathy and retinopathy: the role of inflammation and oxidative stress

Diabetes and hypertension frequently coexist and constitute the most notorious combination for the pathogenesis of diabetic nephropathy and retinopathy. Large clinical trials have clearly demonstrated that tight control of glycemia and/or blood pressure significantly reduces the incidence and progression of diabetic retinopathy (DR) and nephropathy. However, the mechanism by which hypertension interacts with diabetes to induce and/or exacerbate nephropathy and retinopathy is very unclear. Substantial evidence implicates the involvement of chronic inflammation and oxidative stress in the pathogenesis of DR and nephropathy. In addition, hypertension causes oxidative stress and inflammation in the kidney and retina. In the present review, we summarized data obtained from our research along with those from other groups to better understand the role of hypertension in the pathogenesis of diabetic nephropathy and retinopathy. It is suggested that oxidative stress and inflammation may be common denominators of kidney and retinal damage in the concomitant presence of diabetes and hypertension.

Animal models of retinal disease

Diseases of the retina are the leading causes of blindness in the industrialized world. The recognition that animals develop retinal diseases with similar traits to humans has led to not only a dramatic improvement in our understanding of the pathogenesis of retinal disease but also provided a means for testing possible treatment regimes and successful gene therapy trials. With the advent of genetic and molecular biological tools, the association between specific gene mutations and retinal signs has been made. Animals carrying natural mutations usually in one gene now provide well-established models for a host of inherited retinal diseases, including retinitis pigmentosa, Leber congenital amaurosis, inherited macular degeneration, and optic nerve diseases. In addition, the development of transgenic technologies has provided a means by which to study the effects of these and novel induced mutations on retinal structure and function. Despite these advances, there is a paucity of suitable animal models for complex diseases, including age-related macular degeneration (AMD) and diabetic retinopathy, largely because these diseases are not caused by single gene defects, but involve complex genetics and/or exacerbation through environmental factors, epigenetic, or other modes of genetic influence. In this review, we outline in detail the available animal models for inherited retinal diseases and how this information has furthered our understanding of retinal diseases. We also examine how transgenic technologies have helped to develop our understanding of the role of isolated genes or pathways in complex diseases like AMD, diabetes, and glaucoma.

Association between vascular endothelial growth factor and hypertension in children and adolescents type I diabetes mellitus

The aim of the study was to analyse the relationship between the serum level of vascular endothelial growth factor (VEGF) and the incidence of hypertension (HT) in children and adolescents with type I diabetes mellitus (T1DM). One hundred and five patients with T1DM were enrolled in the study. The control group consisted of 30 healthy controls. All the T1DM patients were subjected to biochemical analyses, ophthalmologic examination and 24-h blood pressure monitoring. Besides, all the patients and healthy controls had serum VEGF levels measured with the use of the ELISA methodology. The essence of our research is that patients with T1DM and HT and with microalbuminuria (MA) and diabetic retinopathy (DR) (MA/DR) are characterized by a significantly higher level of VEGF (340.23±93.22 pg ml(-1)) in blood serum in comparison with the group of T1DM patients without HT and MA/DR (183.6±96.6 pg ml(-1)) and with healthy controls (145.32±75.58 pg ml(-1)). In addition, the VEGF level was significantly higher in T1DM patients, who presented all three complications, that is HT, retinopathy and MA in comparison with T1DM patients without HT, but with MA/DR (P=0.036). On the other hand, no statistically significant differences (P=0.19) were noted in the level of VEGF in serum between T1DM patients without HT and MA/DR and the healthy control group. At a further stage of analysis, using the method of multiple regression, it was shown that systolic pressure, HbA1c and duration of disease are independent factors influencing the concentration of VEGF. Summarizing, the measurement of VEGF serum levels allows for the identification of groups of patients who have the highest risk of HT and, subsequently, progression of vascular complications.