Query: ghulam mohammad king saud university

title: Association of HMGB1 with oxidative stress markers and regulators in PDR
abstract: We investigated the link among the proinflammatory cytokine high mobility group box 1 (HMGB1) and 8 hydroxy 2' deoxyguanosine (8 OHdG) as a marker of oxidative DNA damage, the endothelial adhesion molecule and oxidase enzyme vascular adhesion protein 1 (VAP 1) and the inducible cytoprotective molecule heme oxygenase 1 (HO 1) in proliferative diabetic retinopathy (PDR) We correlated the levels of these molecules with clinical disease activity and studied the proinflammatory activities of HMGB1 on rat retinas and human retinal microvascular endothelial cells (HRMECs)  Vitreous samples from 47 PDR and 19 non diabetic patients, epiretinal membranes from 11 patients with PDR, human retinas (16 from diabetic patients and 16 from non diabetic subjects) rat retinas, and HRMECs were studied by enzyme linked immunosorbent assay, immunohistochemistry, western blot immunofluorescence, and RT PCR analyses. In addition, we assessed the adherence of leukocytes to HMGB1 stimulated HRMECs.  HMGB1, 8 OHdG, and soluble VAP 1 (sVAP 1) levels were significantly higher in vitreous samples from PDR patients than in those from non diabetics (p 0.001, <0.0001, <0.0001, respectively) The HMGB1, 8 OHdG, sVAP 1, and HO 1 levels in PDR with active neovascularization were significantly higher than those in inactive PDR (p 0.025, <0.0001, <0.0001, 0.012, respectively) Significant positive correlations were observed between the levels of HMGB1 and the levels of 8 OHdG (r 0.422; p 0.001) and sVAP 1 (r 0.354; p 0.004) and between the levels of 8 OHdG and the levels of sVAP 1 (r 0.598; p<0.0001) In epiretinal membranes, VAP 1 and 8 OHdG were expressed in vascular endothelial cells and stromal cells. Significant increases in the VAP 1 mRNA and protein levels were detected in the RPE, but not in the neuroretina of diabetic patients. Treatment of HRMEC with HMGB1, diabetes induction, and an intravitreal injection of HMGB1 in normal rats induced a significant upregulation of the adhesion molecule intercellular adhesion molecule 1 (ICAM 1) in HRMECs and retinas. On the other hand, the expressions of vascular cell adhesion molecule 1 and VAP 1 were not affected. Oral administration of the HMGB1 inhibitor glycyrrhizin in rats attenuated the diabetes induced upregulation of the retinal ICAM 1 expression. Treatment of HRMECs with HMGB1 increased leukocyte adhesion and induced the upregulation of 8 OHdG and HO 1 and the membranous translocation of VAP 1.  Our results suggest a potential link among the proinflammatory cytokine HMGB1, VAP 1, oxidative stress, and HO 1 in the pathogenesis of PDR.

title: S100A4 is upregulated in proliferative diabetic retinopathy and correlates with markers of angiogenesis and fibrogenesis
abstract: The calcium binding protein S100A4 is implicated in cancer cell invasion and metastasis, the stimulation of angiogenesis, the progression of fibrosis, and inflammatory disorders. We investigated the expression of S100A4 and correlated it with clinical disease activity as well as with the levels of osteopontin (OPN) soluble syndecan 1, and vascular endothelial growth factor (VEGF) in proliferative diabetic retinopathy (PDR) To reinforce the findings at the functional level, we examined the expressions of S100A4 and OPN in the retinas of diabetic rats and in human retinal microvascular endothelial cells (HRMECs) following exposure to VEGF and the proinflammatory cytokine tumor necrosis factor a (TNF a) Methods Vitreous samples from 30 PDR and 30 nondiabetic patients, epiretinal membranes from 14 patients with PDR, the retinas of rats, and HRMECs were studied by enzyme linked immunosorbent assay (ELISA) immunohistochemistry, western blot analysis, and co immunoprecipitation.  ELISA revealed a significant increase in the expressions of S100A4, OPN, soluble syndecan 1, and VEGF in vitreous samples from PDR patients compared to nondiabetic controls (p 0.001; <0.001; <0.001; <0.001, respectively) Significant positive correlations were found between the levels of S100A4, OPN (r 0.52, p <0.001) soluble syndecan 1 (r 0.37, p 0.012) and VEGF (r 0.29, p 0.044) In epiretinal membranes, S100A4 was expressed in the vascular endothelial cells and stromal CD45 expressing leukocytes. A significant positive correlation was detected between the number of blood vessels expressing CD31 and the number of stromal cells expressing S100A4 (r 0.77, p 0.001) Western blot analysis revealed a significant increase in the expressions of S100A4 and both intact and cleaved OPN in vitreous samples from PDR patients compared to nondiabetic controls, as well as in the retinas of diabetic rats. Co immunoprecipitation studies revealed a positive interaction between S100A4 and the receptor for advanced glycation end products (RAGE) in the retinas of diabetic rats. TNF a but not VEGF induced the upregulations of S100A4 and both intact and cleaved OPN in HRMECs.  S100A4 represents a valuable vitreous marker molecule in the pathogenesis of PDR and might become a new target for the treatment of PDR.

title: High Mobility Group Box 1 and Endothelial Cell Angiogenic Markers in the Vitreous from Patients with Proliferative Diabetic Retinopathy
abstract: The aim of this study was to measure the levels of high mobility group box 1 (HMGB1) in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR) and to correlate its levels with clinical disease activity and the levels of vascular endothelial growth factor (VEGF) the angiogenic cytokine granulocyte colony stimulating factor (G CSF) the endothelial cell angiogenic markers soluble vascular endothelial cadherin (sVE cadherin) and soluble endoglin (sEng) Vitreous samples from 36 PDR and 21 nondiabetic patients were studied by enzyme linked immunosorbent assay. HMGB1, VEGF, sVE cadherin, and sEng levels were significantly higher in PDR patients than in nondiabetics (P 0.008; <0.001; <0.001; 0.003, resp. G CSF was detected in only 3 PDR samples. In the whole study group, there was significant positive correlation between the levels of HMGB1, and sVE cadherin (r 0.378, P 0.007) In PDR patients, there was significant negative correlation between the levels of sVE cadherin and sEng (r 0.517, P 0.0005) Exploratory regression analysis identified significant associations between active PDR and high levels of VEGF (odds ratio 76.4; 95% confidence interval 6.32 923) and high levels of sEng (odds ratio 6.01; 95% confidence interval 1.25 29.0) Our findings suggest that HMGB1, VEGF, sVE cadherin and sEng regulate the angiogenesis in PDR.

title: The Tumor Necrosis Factor Superfamily Members TWEAK, TNFSF15 and Fibroblast Growth Factor Inducible Protein 14 Are Upregulated in Proliferative Diabetic Retinopathy
abstract: Tumor necrosis factor like weak inducer of apoptosis (TWEAK) and tumor necrosis factor superfamily member 15 (TNFSF15) members of the TNF superfamily, play important roles in the modulation of inflammation and neovascularization. TWEAK activity is mediated via binding to fibroblast growth factor inducible molecule 14 (Fn14) We investigated the expression of TWEAK, Fn14 and TNFSF15 and the correlation between TWEAK levels and the levels of the inflammatory biomarker soluble intercellular adhesion molecule 1 (sICAM 1) in proliferative diabetic retinopathy (PDR) In addition, we examined the expression of FN14 and TNFSF15 in retinas of diabetic rats.  Vitreous samples from 34 PDR and 23 nondiabetic patients were studied by enzyme linked immunosorbent assay and Western blot analysis. Epiretinal membranes from 14 patients with PDR were studied by immunohistochemistry. The retinas of rats were examined by Western blot analysis.  We identified a significant increase in the expression of TWEAK, Fn14, TNFSF15 and sICAM 1 in vitreous samples from PDR patients compared to controls. A significant positive correlation was found between levels of TWEAK and levels of sICAM 1 (r 0.3, p 0.02) In epiretinal membranes, TWEAK and TNFSF15 protein expression was confined to vascular endothelial cells, monocytes/macrophages and myofibroblasts. Significant positive correlations were observed between the number of blood vessels expressing CD34 and the number of blood vessels expressing TWEAK (r 0.670; p 0.017) and TNFSF15 (r 0.784; p 0.001) The expression level of TNFSF15 was upregulated in the retinas of diabetic rats, whereas Fn14 was not upregulated.  Our findings suggest that TNFSF15 and the TWEAK/Fn14 pathway are novel mediators involved in persistent inflammation and modulation of pathological neovascularization associated with PDR.

title: Cellular Mechanisms of High Mobility Group 1 (HMGB 1) Protein Action in the Diabetic Retinopathy
abstract: Diabetic retinopathy is one of the main microvascular complications of diabetes and remains one of the leading causes of blindness worldwide. Recent studies have revealed an important role of inflammatory and proangiogenic high mobility group 1 (HMGB 1) cytokine in diabetic retinopathy. To elucidate cellular mechanisms of HMGB 1 activity in the retina, we performed this study. The histological features of diabetic retinopathy include loss of blood vessel pericytes and endothelial cells, as well as abnormal new blood vessel growth. To establish the role of HMGB 1 in vulnerability of endothelial cells and pericytes, cultures of these cells, or co cultures with glial cells, were treated with HMGB 1 and assessed for survival after 24 hours. The expression levels of the cytokines, chemokines, and cell adhesion molecules in glial and endothelial cells were tested by quantitative RT PCR to evaluate changes in these cells after HMGB 1 treatment. Animal models of neovascularization were also used to study the role of HMGB 1 in the retina. We report that pericyte death is mediated by HMGB 1 induced cytotoxic activity of glial cells, while HMGB 1 can directly mediate death of endothelial cells. We also found that HMGB 1 affects endothelial cell activity. However, we did not observe a difference in the levels of neovascularization between HMGB 1 treated eyes compared to the control eyes, nor in the levels of proangiogenic cytokine VEGF A expression between glial cells treated with HMGB 1 and control cells. Our data also indicate that HMGB 1 is not involved in retinal neovascularization in the oxygen induced retinopathy model. Thus, our data suggest that retinal pericyte and endothelial injury and death in diabetic retinopathy may be due to HMGB 1 induced cytotoxic activity of glial cells as well as the direct effect of HMGB 1 on endothelial cells. At the same time, our findings indicate that HMGB 1 plays an insignificant role in retinal and choroidal neovascularization.

title: Expression of lysophosphatidic acid, autotaxin and acylglycerol kinase as biomarkers in diabetic retinopathy
abstract: The proinflammatory lysophosphatidic acid (LPA) is a potent activator of several transcriptional factors and signaling pathways and a potent modulator of genes involved in inflammation, angiogenesis and fibrosis. This study was conducted to measure the levels of LPA and LPA producing enzymes, autotaxin (ATX) and acylglycerol kinase (AGK) in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR) and to correlate their levels with clinical disease activity and the level of vascular endothelial growth factor (VEGF) In addition, we examined the expression of ATX, AGK and VEGF receptor 2 (VEGFR 2) in the retinas of diabetic rats. Vitreous samples from 42 PDR and 35 nondiabetic patients were studied by enzyme linked immunosorbent assay. Vitreous samples and retinas of rats were examined by Western blot analysis. VEGF, LPA and AGK levels in vitreous samples from PDR patients were significantly higher than those in control patients without diabetes (p 0.001 for all comparisons) ATX levels in PDR with active neovascularization and inactive PDR were significantly lower than those in nondiabetic patients (p 0.045) Mean VEGF and AGK levels in PDR with active neovascularization were significantly higher than those in inactive PDR and nondiabetic patients (p 0.001 for both comparisons) A significant correlation was observed between levels of VEGF and levels of AGK in PDR patients (r 0.954; p 0.001) Western blot analysis revealed a significant increase in the expression of AGK and VEGFR 2 in vitreous samples and the retinas of diabetic rats compared to nondiabetic controls, whereas ATX was significantly downregulated. Our findings suggest that ATX AGK LPA signaling axis might be an important player in the development and progression of diabetic retinopathy.

title: Poly (ADP Ribose) Polymerase Mediates Diabetes Induced Retinal Neuropathy
abstract: Retinal neuropathy is an early event in the development of diabetic retinopathy. One of the potential enzymes that are activated by oxidative stress in the diabetic retina is poly (ADP ribose) polymerase (PARP) We investigated the effect of the PARP inhibitor 1,5 isoquinolinediol on the expression of the neurodegeneration mediators and markers in the retinas of diabetic rats. After two weeks of streptozotocin induced diabetes, rats were treated with 1,5 isoquinolinediol (3 mg/kg/day) After 4 weeks of diabetes, the retinas were harvested and the levels of reactive oxygen species (ROS) were determined fluorometrically and the expressions of PARP, phosporylated ERK1/2, BDNF, synaptophysin, glutamine synthetase (GS) and caspase 3 were determined by Western blot analysis. Retinal levels of ROS, PARP 1/2, phosphorylated ERK1/2, and cleaved caspase 3 were significantly increased, whereas the expressions of BDNF synaptophysin and GS were significantly decreased in the retinas of diabetic rats, compared to nondiabetic rats. Administration of 1,5 isoquinolinediol did not affect the metabolic status of the diabetic rats, but it significantly attenuated diabetes induced upregulation of PARP, ROS, ERK1/2 phosphorylation, and cleaved caspase 3 and downregulation of BDNF, synaptophysin, and GS. These findings suggest a beneficial effect of the PARP inhibitor in increasing neurotrophic support and ameliorating early retinal neuropathy induced by diabetes.

title: The Poly(ADP Ribose)Polymerase 1 Inhibitor 1,5 Isoquinolinediol Attenuate Diabetes Induced NADPH Oxidase Derived Oxidative Stress in Retina.
abstract: To examine the effects of poly(ADP ribose)polymerase 1 (PARP 1) inhibitor 1,5 isoquinolinediol (IQ) on nicotinamide adenine dinucleotide phosphate (NADPH) oxidase derived oxidative stress in diabetic retina.  Streptozotocin induced diabetic rats were treated with IQ. The NADPH oxidase enzyme activity was determined by luminometer. Expression of gp91phox, P47phox and nitrated proteins was examined by western blot. Interaction between gp91phox and P47phox was determined by coimmunoprecipitation. Enzyme linked immunosorbent assay was utilized to measure the level of retinal total antioxidant capacity. We also studied the effect of the IQ on hydrogen peroxide (H2O2) induced cleavage of PARP 1 and caspase 3 in human retinal Muller glial cells.  Treatment of retinal Muller cells with H2O2 induced PARP 1 and caspase 3 cleavage that was attenuated by IQ cotreatment. Diabetes upregulated PARP 1, NADPH oxidase enzyme activity, gp91phox, P47phox, nitrated protein expression and interaction between gp91phox and P47phox, and downregulated total antioxidant capacity in the retinas compared with nondiabetic rats. Administration of IQ did not affect the metabolic status of the diabetic rats, but it significantly attenuated diabetes induced upregulation of NADPH oxidase enzyme activity and expressions of gp91phox, P47phox, and nitrated proteins and interaction between gp91phox and P47phox. In addition, IQ ameliorated diabetes induced downregulation of total antioxidant capacity in the retina.  PARP 1 inhibition by IQ protects diabetic retina from NADPH oxidase derived oxidative stress. Thus, inhibition of PARP 1 could have potential therapeutic value in preventing the development of diabetic retinopathy.

title: Role of matrix metalloproteinase 2 and 9 in the development of diabetic retinopathy
abstract: Diabetic retinopathy represents the most common causes of vision loss in patients affected by diabetes mellitus. The cause of vision loss in diabetic retinopathy is complex and remains incompletely understood. One of the earliest changes in the development of retinopathy is the accelerated apoptosis of retinal microvascular cells and the formation of acellular capillaries by unknown mechanism. Results of a recent research suggest an important role of matrix metalloproteinases (MMPs) in the development of diabetic retinopathy. MMPs are a large family of proteinases that remodel extracellular matrix components, and under pathological condition, its induction is considered as a negative regulator of cell survival; and in diabetes, latent MMPs are activated in the retina and its capillary cells, and activation of MMP 2 and 9 induces apoptosis of retinal capillary cells. This review will focus on the MMP 2 and MMP 9 in the diabetic retina with special reference to oxidative stress, mitochondria dysfunction, inflammation and angiogenesis, as well as summarizing the current information linking these proteins to pathogenesis of diabetic retinopathy.

title: Coexpression of heparanase activity, cathepsin L, tissue factor, tissue factor pathway inhibitor, and MMP 9 in proliferative diabetic retinopathy
abstract: Heparanase cleaves heparan sulfate side chains of heparan sulfate proteoglycans, activity that is implicated in angiogenesis. Proteolytic cleavage of proheparanase by cathepsin L leads to the formation of catalytically active heparanase. We investigated the expression levels of heparanase enzymatic activity and correlated these with the levels of cathepsin L, the angiogenic factors tissue factor (TF) and matrix metalloproteinase 9 (MMP 9) and the angiostatic factor tissue factor pathway inhibitor (TFPI) in proliferative diabetic retinopathy (PDR) Methods Vitreous samples from 25 patients with PDR and 20 nondiabetic patients and epiretinal membranes from 12 patients with PDR were studied with enzyme linked immunosorbent assay, western blot analysis, and immunohistochemistry.  We observed a significant increase in the expression of heparanase activity in vitreous samples from patients with PDR compared to the nondiabetic controls (p=0.027) Significant positive correlations were found between the levels of heparanase activity and the levels of cathepsin L (r=0.51; p=0.001) TF (r=0.6; p<0.0001) and TFPI (r=0.49; p=0.001) The expression levels of cathepsin L (p=0.019) TF (p<0.0001) TFPI (p<0.0001) and MMP 9 (p=0.029) were significantly higher in the vitreous samples with detected heparanase activity compared to the vitreous samples with undetected heparanase activity. Western blot analysis demonstrated proteolytic cleavage of TFPI in the vitreous samples from patients with PDR. In the epiretinal membranes, cathepsin L, TF, and TFPI were expressed in vascular endothelial cells and CD45 expressing leukocytes. Significant positive correlations were detected between the number of blood vessels that expressed CD31 and the number of blood vessels that expressed TF (r=0.9; p<0.0001) and TFPI (r=0.81; p=0.001)  The coexpression of these angiogenesis regulatory factors suggests cross talk between these factors and pathogenesis of PDR angiogenesis.