Cannabinoid 1 receptor activation contributes to vascular inflammation and cell death in a mouse model of diabetic retinopathy and a human retinal cell line

Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Augusta, GA, USA.
Diabetologia (Impact Factor: 6.67). 03/2011; 54(6):1567-78. DOI: 10.1007/s00125-011-2061-4
Source: PubMed

ABSTRACT Recent studies have demonstrated that cannabinoid-1 (CB(1)) receptor blockade ameliorated inflammation, endothelial and/or cardiac dysfunction, and cell death in models of nephropathy, atherosclerosis and cardiomyopathy. However the role of CB(1) receptor signalling in diabetic retinopathy remains unexplored. Using genetic deletion or pharmacological inhibition of the CB(1) receptor with SR141716 (rimonabant) in a rodent model of diabetic retinopathy or in human primary retinal endothelial cells (HREC) exposed to high glucose, we explored the role of CB(1) receptors in the pathogenesis of diabetic retinopathy.
Diabetes was induced using streptozotocin in C57BL/6J Cb(1) (also known as Cnr1)(+/+) and Cb(1)(-/-) mice aged 8 to 12 weeks. Samples from mice retina or HREC were used to determine: (1) apoptosis; (2) activity of nuclear factor kappa B, intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), poly (ADP-ribose) polymerase and caspase-3; (3) content of 3-nitrotyrosine and reactive oxygen species; and (4) activation of p38/Jun N-terminal kinase/mitogen-activated protein kinase (MAPK).
Deletion of CB(1) receptor or treatment of diabetic mice with CB(1) receptor antagonist SR141716 prevented retinal cell death. Treatment of diabetic mice or HREC cells exposed to high glucose with SR141716 attenuated the oxidative and nitrative stress, and reduced levels of nuclear factor κB, ICAM-1 and VCAM-1. In addition, SR141716 attenuated the diabetes- or high glucose-induced pro-apoptotic activation of MAPK and retinal vascular cell death.
Activation of CB(1) receptors may play an important role in the pathogenesis of diabetic retinopathy by facilitating MAPK activation, oxidative stress and inflammatory signalling. Conversely, CB(1) receptor inhibition may be beneficial in the treatment of this devastating complication of diabetes.

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Available from: Pal Pacher, Sep 25, 2015
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    • "Therefore, our results suggest that CB2 activation reduces oxidative stress which is in accordance with the previous studies [17, 23]. Conversely, CB1 receptor activation is related to the augmentation of oxidative stress as well as other depressive effects [49–52]. In fact, selective CB1 antagonists have been speculated as a potential tool for the treatment of cardiovascular disease [32, 49]. "
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    ABSTRACT: Hypercholesterolemia is one of the most important risk factors for erectile dysfunction, mostly due to the impairment of oxidative stress and endothelial function in the penis. The cannabinoid system might regulate peripheral mechanisms of sexual function; however, its role is still poorly understood. We investigated the effects of CB2 activation on oxidative stress and fibrosis within the corpus cavernosum of hypercholesterolemic mice. Apolipoprotein-E-knockout mice were fed with a western-type diet for 11 weeks and treated with JWH-133 (selective CB2 agonist) or vehicle during the last 3 weeks. CB2 receptor expression, total collagen content, and reactive oxygen species (ROS) production within the penis were assessed. In vitro corpus cavernosum strips preparation was performed to evaluate the nitric oxide (NO) bioavailability. CB2 protein expression was shown in cavernosal endothelial and smooth muscle cells of wild type and hypercholesterolemic mice. Treatment with JWH-133 reduced ROS production and NADPH-oxidase expression in hypercholesterolemic mice penis. Furthermore, JWH-133 increased endothelial NO synthase expression in the corpus cavernosum and augmented NO bioavailability. The decrease in oxidative stress levels was accompanied with a reduction in corpus cavernosum collagen content. In summary, CB2 activation decreased histological features, which were associated with erectile dysfunction in hypercholesterolemic mice.
    Clinical and Developmental Immunology 11/2013; 2013(9):263846. DOI:10.1155/2013/263846 · 2.93 Impact Factor
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    • "A recent report suggested that p38 and c-Jun N-terminal kinase mitogen-activated protein kinase pathways are essential for caspase-14 expression in normal human epidermal keratinocytes [42]. In retina, p38 mitogen-activated protein kinase plays a crucial role in the pathogenesis of DR via inflammatory and proapoptotic cell death pathways [43,44]. Further investigation is needed to delineate fully the signal transduction pathways involved in regulating caspase-14 expression and/or activity and function during DR. "
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    ABSTRACT: The purpose of this study was to evaluate caspase-14 expression in the retina under normal and diabetic conditions, and to determine whether caspase-14 contributes to retinal microvascular cell death under high glucose conditions. Quantitative real-time polymerase chain reaction and western blot analysis were used to evaluate caspase-14 expression in retinal cells, including pericytes (PCs), endothelial cells (ECs), astrocytes (ACs), choroidal ECs, and retinal pigment epithelium (RPE) cells. We also determined caspase-14 expression in the retinas of human subjects with or without diabetic retinopathy (DR) and in experimental diabetic mice. Retinal ECs and PCs were infected with adenoviruses expressing human caspase-14 or green fluorescent protein. Caspase-14 expression was also assessed in retinal vascular cells cultured under high glucose conditions. The number of apoptotic cells was determined with terminal deoxynucleotidyl transferase dUTP nick end labeling staining and confirmed by determining the levels of cleaved poly (ADP-ribose) polymerase-1 and caspase-3. Our experiments demonstrated that retinal ECs, PCs, ACs, choroidal ECs, and RPE cells expressed caspase-14, and DR was associated with upregulation and/or activation of caspase-14 particularly in retinal vasculature. High glucose induced marked elevation of the caspase-14 level in retinal vascular cells. There was a significant increase in the apoptosis rate and the levels of cleaved poly (ADP-ribose) polymerase-1 and caspase-3 in retinal ECs and PCs overexpressing caspase-14. Our findings indicate that caspase-14 might play a significant role in the pathogenesis of DR by accelerating retinal PC and EC death. Further investigations are required to elaborate the underlying mechanisms.
    Molecular vision 07/2012; 18:1895-906. · 1.99 Impact Factor
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    • "CB1R activation in coronary artery endothelial cells (29), cardiomyocytes (26,27), and inflammatory cells (28,30) mediates MAPK activation, reactive oxygen species (ROS) generation, and inflammatory response promoting atherosclerosis (31) and cardiac dysfunction (27,28). Furthermore, elevated endocannabinoid plasma levels have recently been associated with coronary circulatory dysfunction in human obesity (32), and CB1R blockade or its genetic deletion attenuated proteinuria and/or vascular inflammation and cell death in experimental models of type 1 diabetic nephropathy (33) and/or retinopathy (34). Beneficial effect of CB1 blockade has also been reported in rodent models of type 1 diabetic neuropathy and in various high glucose–induced in vitro experimental paradigms (rev. in 35). "
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