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Jung KI, Kim JH, Han JS, Park CK. Exploring Neuroprotective Effects of Topical Brimonidine in Experimental Diabetic Retinopathy. In Vivo 2024; 38:1609-1620. [PMID: 38936912 PMCID: PMC11215565 DOI: 10.21873/invivo.13611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/09/2024] [Accepted: 04/11/2024] [Indexed: 06/29/2024]
Abstract
BACKGROUND/AIM Diabetic retinopathy is a leading cause of blindness worldwide, characterized by neurovascular dysfunction. This study aimed to investigate the impact of brimonidine, a selective adrenoceptor agonist, on diabetic retinal neurodegeneration, recognizing the critical role of neurodegeneration in diabetic retinopathy. MATERIALS AND METHODS Streptozotocin-induced diabetes was established in adult male Sprague-Dawley rats to mimic diabetic retinopathy. Rats, except non-diabetic control rats, received topical applications of 0.15% brimonidine tartrate (treatment group) or balanced salt solution (diabetic control group) twice daily following diabetes induction. Each group comprised six randomly assigned animals. Retinal samples were analyzed using immunofluorescence staining, apoptosis assay, and western blot. RESULTS Topical brimonidine treatment reduced apoptosis of retinal ganglion cells at 8 weeks after induction of diabetes (p<0.05). Glial activation induced by diabetes was reduced by brimonidine treatment. Immunoblot and immunofluorescence assay revealed that the decrease in phospho- protein kinase B (AKT) level resulting from diabetes was also attenuated by brimonidine (p<0.05). Furthermore, brimonidine alleviated the decrease in anti-apoptotic proteins [BCL2 apoptosis regulator (BCL2) and BCL-xl] induced by diabetes (p<0.05). Elevation of phospho-p38 mitogen-activated protein kinase (p38MAPK) and p53 in diabetic rats were reduced by brimonidine (p<0.05). Additionally, brimonidine treatment attenuated the upregulation of the pro-apoptotic molecule BCL-2 associated X in retinas of diabetic rats (p<0.05). CONCLUSION These findings suggest that topical brimonidine treatment may protect retinal ganglion cells in experimental diabetes by modulating the AKT pathway and reducing pro-apoptotic p38MAPK levels. This presents a potential neuroprotective approach in diabetes, offering the advantage of localized treatment without the added burden of oral medication.
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Affiliation(s)
- Kyoung In Jung
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Jie Hyun Kim
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Jeong-Sun Han
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Chan Kee Park
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
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Zheng Z, Yu X. Insulin resistance in the retina: possible implications for certain ocular diseases. Front Endocrinol (Lausanne) 2024; 15:1415521. [PMID: 38952394 PMCID: PMC11215121 DOI: 10.3389/fendo.2024.1415521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 06/05/2024] [Indexed: 07/03/2024] Open
Abstract
Insulin resistance (IR) is becoming a worldwide medical and public health challenge as an increasing prevalence of obesity and metabolic disorders. Accumulated evidence has demonstrated a strong relationship between IR and a higher incidence of several dramatically vision-threatening retinal diseases, including diabetic retinopathy, age-related macular degeneration, and glaucoma. In this review, we provide a schematic overview of the associations between IR and certain ocular diseases and further explore the possible mechanisms. Although the exact causes explaining these associations have not been fully elucidated, underlying mechanisms of oxidative stress, chronic low-grade inflammation, endothelial dysfunction and vasoconstriction, and neurodegenerative impairments may be involved. Given that IR is a modifiable risk factor, it may be important to identify patients at a high IR level with prompt treatment, which may decrease the risk of developing certain ocular diseases. Additionally, improving IR through the activation of insulin signaling pathways could become a potential therapeutic target.
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Affiliation(s)
- Zhaoxia Zheng
- Department of Ophthalmology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, China
- Graduate School of Peking Union Medical College, Beijing, China
| | - Xiaobing Yu
- Department of Ophthalmology, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, China
- Graduate School of Peking Union Medical College, Beijing, China
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Qin P, Zhou P, Huang Y, Long B, Gao R, Zhang S, Zhu B, Li YQ, Li Q. Upregulation of rate-limiting enzymes in cholesterol metabolism by PKCδ mediates endothelial apoptosis in diabetic wound healing. Cell Death Discov 2024; 10:263. [PMID: 38811564 PMCID: PMC11137154 DOI: 10.1038/s41420-024-02030-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 05/03/2024] [Accepted: 05/14/2024] [Indexed: 05/31/2024] Open
Abstract
Diabetic foot ulcer (DFU) is a prevalent complication of diabetes that poses significant challenges in terms of treatment and management. It is characterized by heightened endothelial apoptosis and impaired angiogenesis. In this study, we aimed to investigate the role of protein kinase Cδ (PKCδ) in regulating endothelial apoptosis in diabetic wounds by promoting cholesterol biosynthesis. The expression of PKCδ was increased in human umbilical vascular endothelial cells (HUVECs) cultivated in high glucose medium and skin tissue isolated from diabetic mice. High glucose-induced HUVECs apoptosis was reduced by PKCδ inhibition with siRNA or rottlerin. RNA-seq identified two enzymes, 3-hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), as the downstream of PKCδ. PKCδ knockdown or inhibition suppressed the expression of HMGCS1 and HMGCR and lowered free cholesterol (FC) levels. Cholesterol restored high glucose-induced apoptosis in siRNA- or rottlerin-treated HUVECs. In vivo use of rosuvastatin calcium, an inhibitor of HMGCR, downregulated free cholesterol levels and accelerated the wound healing process. In conclusion, PKCδ expression in endothelial cells was activated by high glucose, which subsequently upregulates the expression of two enzymes catalyzing cholesterol biosynthesis, HMGCS1 and HMGCR. Enhanced cholesterol biosynthesis raises free cholesterol levels, promotes endothelial apoptosis, and finally delays wound healing.
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Affiliation(s)
- Peiliang Qin
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Peng Zhou
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yating Huang
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Binbin Long
- General Surgery Department, Taihe Hospital Affiliated to Hubei University of Medicine, Shiyan, Hubei, China
| | - Ruikang Gao
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Shan Zhang
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Bingjie Zhu
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yi-Qing Li
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Qin Li
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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Lu C, Lin C, Lu Y, Tsai H, Lin C, Wu C. CDDO regulates central and peripheral sensitization to attenuate post-herpetic neuralgia by targeting TRPV1/PKC-δ/p-Akt signals. J Cell Mol Med 2024; 28:e18131. [PMID: 38426931 PMCID: PMC10906387 DOI: 10.1111/jcmm.18131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/17/2023] [Accepted: 12/29/2023] [Indexed: 03/02/2024] Open
Abstract
Postherpetic neuralgia (PHN) is a notorious neuropathic pain featuring persistent profound mechanical hyperalgesia with significant negative impact on patients' life quality. CDDO can regulate inflammatory response and programmed cell death. Its derivative also protects neurons from damages by modulating microglia activities. As a consequence of central and peripheral sensitization, applying neural blocks may benefit to minimize the risk of PHN. This study aimed to explore whether CDDO could generate analgesic action in a PHN-rats' model. The behavioural test was determined by calibrated forceps testing. The number of apoptotic neurons and degree of glial cell reaction were assessed by immunofluorescence assay. Activation of PKC-δ and the phosphorylation of Akt were measured by western blots. CDDO improved PHN by decreasing TRPV1-positive nociceptive neurons, the apoptotic neurons, and reversed glial cell reaction in adult rats. It also suppressed the enhanced PKC-δ and p-Akt signalling in the sciatic nerve, dorsal root ganglia (DRG) and spinal dorsal horn. Our research is the promising report demonstrating the analgesic and neuroprotective action of CDDO in a PHN-rat's model by regulating central and peripheral sensitization targeting TRPV1, PKC-δ and p-Akt. It also is the first study to elucidate the role of oligodendrocyte in PHN.
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Affiliation(s)
- Chun‐Ching Lu
- Department of Orthopaedics and TraumatologyNational Yang Ming Chiao Tung University HospitalYilanTaiwan
- Department of Orthopaedics, School of MedicineNational Yang Ming Chiao Tung UniversityTaipeiTaiwan
- Department of Orthopaedics and TraumatologyTaipei Veterans General HospitalTaipeiTaiwan
| | - Chia‐Yang Lin
- Department of Nuclear MedicineKaohsiung Medical University HospitalKaohsiungTaiwan
| | - Ying‐Yi Lu
- Department of DermatologyKaohsiung Veterans General HospitalKaohsiungTaiwan
- Department of Post‐Baccalaureate Medicine, School of Medicine, College of MedicineNational Sun Yat‐sen UniversityKaohsiungTaiwan
- Shu‐Zen Junior College of Medicine and ManagementKaohsiungTaiwan
| | - Hung‐Pei Tsai
- Division of Neurosurgery, Department of SurgeryKaohsiung Medical University HospitalKaohsiungTaiwan
| | - Chih‐Lung Lin
- Division of Neurosurgery, Department of SurgeryKaohsiung Medical University HospitalKaohsiungTaiwan
- Department of Surgery, School of Medicine, College of MedicineKaohsiung Medical UniversityKaohsiungTaiwan
| | - Chieh‐Hsin Wu
- Division of Neurosurgery, Department of SurgeryKaohsiung Medical University HospitalKaohsiungTaiwan
- Department of Surgery, School of Medicine, College of MedicineKaohsiung Medical UniversityKaohsiungTaiwan
- Center for Big Data ResearchKaohsiung Medical UniversityKaohsiungTaiwan
- Drug Development and Value Creation Research CenterKaohsiung Medical UniversityKaohsiungTaiwan
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Pal S, Rao GN, Pal A. Inflammation and apoptosis, two key events induced by hyperglycemia mediated reactive nitrogen species in RGC-5 cells. Life Sci 2021; 279:119693. [PMID: 34111464 DOI: 10.1016/j.lfs.2021.119693] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 05/23/2021] [Accepted: 05/31/2021] [Indexed: 12/21/2022]
Abstract
Nitrosative stress plays a critical role in retinal injury in high glucose (HG) environment of eye, but the mechanisms remain poorly understood. Here we tested the hypothesis that HG induced reactive nitrogen species (RNS) production acts as a key functional mediator of antioxidant depletion, mitochondrial dysfunction, biomolecule damage, inflammation and apoptosis. Our findings illustrated that exposure of cultured RGC-5 cells to HG significantly disrupts the antioxidant defense mechanism and mitochondrial machineries by increasing the loss of mitochondrial membrane potential (ΔѰM) and elevating mitochondrial mass. Furthermore, we used biochemical tools to analyze the changes in metabolites, sulfur amino acids (SAAs) such as L-glutathione (GSH) and L-cysteine (Cys), in the presence of HG environment. These metabolic changes were followed by an increase in glycolytic flux that is phosphofructokinase-2 (PFK-2) activity. Moreover, HG exposure results in a significant disruption of protein carbonylation (PC) and lipid peroxidation (LPO), downregulation of OGG1 and increase in 8-OHdG accumulations in RGC-5 cells. In addition, our results demonstrated that HG environment coinciding with increased expression of inflammatory mediators, cell cycle deregulation, decreased in cell viability and expression of FoxOs, increased lysosomal content leading to apoptosis. Pre-treatment of selective inhibitors of RNS significantly reduced the HG-induced cell cycle deregulation and apoptosis in RGC-5 cells. Collectively, these results illustrated that accumulated RNS exacerbates the antioxidant depletion, mitochondrial dysfunction, biomolecule damage, inflammation and apoptosis induced by HG exposure in RGC-5 cells. Treatment of pharmacological inhibitors attenuated the HG induced in retinal cells.
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Affiliation(s)
- Sweta Pal
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar 751024, India
| | - G Nageswar Rao
- Department of Ophthalmology, Kalinga Institute of Medical Sciences, Kalinga Institute of Industrial Technology, Bhubaneswar 751024, India
| | - Arttatrana Pal
- School of Biotechnology, Kalinga Institute of Industrial Technology, Bhubaneswar 751024, India; Department of Zoology, School of Life Sciences, Mahatma Gandhi Central University, Motihari 845401, India.
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Lu X, Li H, Wang S. Hydrogen Sulfide Protects Against Uremic Accelerated Atherosclerosis via nPKCδ/Akt Signal Pathway. Front Mol Biosci 2021; 7:615816. [PMID: 33644113 PMCID: PMC7903246 DOI: 10.3389/fmolb.2020.615816] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 12/22/2020] [Indexed: 01/09/2023] Open
Abstract
Background: Cardiovascular disease is the most common complication and leading cause of death in maintenance hemodialysis patients. Previous studies have found that disorders of cystathionine-gamma-lyase/hydrogen sulfide (CSE/H2S) system in maintenance hemodialysis patients are correlated with the risk of cardiovascular disease. Although the role of CSE/H2S system in UAAS has been preliminarily explored, the molecular mechanism of CSE/H2S is still not systematically elaborated, and the molecular mechanism of nPKCδ and its related signaling pathway in UAAS is still not thoroughly studied. Methods: Forty chronic kidney disease (CHD) patients were studied and the activation of nPKCδ in peripheral blood mononuclear cells (PBMCs) were detected. ApoE−/− mice aged 6 weeks were treated with 5/6 nephrectomy and high-fat diet to make UAAS model. They were divided into Sham group (Sham group), UAAS group (UAAS group), UAAS+L-cysteine group (UAAS+L-cys group), UAAS+sodium hydrosulfide group (UAAS+NaHS group) and UAAS+propargylglycine group (UAAS+PPG group). The UAAS+L-cys group, UAAS+NaHS group and UAAS+PPG group were respectively given L-cys, NaHS and PPG by intraperitoneal injection. The aorta was taken 6 weeks after surgery. Western blot was used to detect the activation of nPKCδ, the phosphorylation of Akt, and the expression of VCAM-1 in the aorta of mice. Results: The membrane translocation of nPKCδ in CHD patients with plaque was higher than that in CHD patients without plaque. The membrane translocation of nPKCδ and the expression of VCAM-1 in UAAS group was higher than sham group, L-cys or NaHS injection could suppress the membrane translocation of nPKCδ and the expression of VCAM-1, but PPG treatment resulted in more membrane translocation of nPKCδ and the expression of VCAM-1 (P<0.05, n=6 per group). Akt phosphorylation in UAAS group was lower than sham group, and L-cys or NaHS injection could suppress the degradation of Akt phosphorylation, but PPG treatment resulted in more decrease in the Akt phosphorylation (P<0.05, n=6 per group). Conclusion: Endogenous CSE/H2S system protected against the formation of UAAS via nPKCδ/Akt signal pathway. The imbalance of CSE/H2S system may participate in the formation of UAAS by affecting the expression of downstream molecule VCAM-1, which may be mediated by nPKCδ/Akt signaling pathway.
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Affiliation(s)
- Xiangxue Lu
- Department of Blood Purification, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
| | - Han Li
- Department of Blood Purification, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
| | - Shixiang Wang
- Department of Blood Purification, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
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Umme Hani, Kandagalla S, Sharath BS, Jyothsna K, Manjunatha H. Network Pharmacology Approach Uncovering Pathways Involved in Targeting Hsp90 Through Curcumin and Epigallocatechin to Control Inflammation. Curr Drug Discov Technol 2019; 18:127-138. [PMID: 31820701 DOI: 10.2174/1570163816666191210145652] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/07/2019] [Accepted: 10/15/2019] [Indexed: 11/22/2022]
Abstract
AIMS To fetch pathways involved in targetting Hsp90 through Curcumin and Epigallocatechin through Network pharmacological approach. BACKGROUND Hsp90 is a molecular chaperone involved in stabilizing inflammatory protein which may lead to chronic diseases. The herbal compounds Curcumin and Epigallocatechin processing antiinflammatory properties are known to follow a common pathway and control the expression of Hsp90. OBJECTIVE To collect the gene targets of Hsp90, Curcumin and Epigallocatechin in order to understand protein-protein interactions of gene targets by constructing the interactome to identify the hub proteins. Hub proteins docking was performed with curcumin and epigallocatechin. Finally, hub proteins involvement with various human diseases were identified. METHODS The gene targets of Hsp90, Curcumin and Epigallocatechin were obtained from there respective databases. Protein-protein interactions of Pkcδ-Nrf2 and Tlr4 pathway gene targets were collected from String database. Protein interaction network was constructed and merged to get intercession network in cytoscape and Cluego was used to predict the disease related target genes. Docking of ligands to target proteins was carried out using Autodock vina tool. RESULT The main key regulators of Curcumin and Epigallocatechin were identified particularly from Pkcδ-Nrf2 and Tlr4 pathway. CONCLUSION The combined action of Curcumin and Epigallocatechin can reduce the expression of Hsp90 eventually controlling the inflammation.
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Affiliation(s)
- Umme Hani
- Department of Biotechnology, Janana Sahyadri, Kuvempu University, Shankaraghatta, Shivamogga, Karnataka 577451, India
| | - Shivananda Kandagalla
- Department of Biotechnology, Janana Sahyadri, Kuvempu University, Shankaraghatta, Shivamogga, Karnataka 577451, India
| | - B S Sharath
- Department of Biotechnology, Janana Sahyadri, Kuvempu University, Shankaraghatta, Shivamogga, Karnataka 577451, India
| | - K Jyothsna
- Department of Biotechnology, Janana Sahyadri, Kuvempu University, Shankaraghatta, Shivamogga, Karnataka 577451, India
| | - Hanumanthappa Manjunatha
- Department of Biotechnology, Janana Sahyadri, Kuvempu University, Shankaraghatta, Shivamogga, Karnataka 577451, India
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Kim D, Mecham RP, Nguyen NH, Roy S. Decreased lysyl oxidase level protects against development of retinal vascular lesions in diabetic retinopathy. Exp Eye Res 2019; 184:221-226. [PMID: 31022398 DOI: 10.1016/j.exer.2019.04.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/19/2019] [Accepted: 04/16/2019] [Indexed: 12/14/2022]
Abstract
Retinal capillary basement membrane (BM) thickening is closely associated with the development of vascular lesions in diabetic retinopathy. Thickened capillary BM can compromise blood-retinal-barrier characteristics and contribute to retinal vascular permeability, a significant clinical manifestation of diabetic retinopathy. We have previously shown that high glucose increases the expression and activity of lysyl oxidase (LOX), a crosslinking enzyme, in retinal endothelial cells. Additionally, concomitant with overexpression of LOX, increased vascular permeability was observed in diabetic rat retinas. However, it is unknown whether decreasing LOX overexpression may have protective effects against development of retinal vascular lesions in diabetes. To investigate whether reduced LOX level protects against diabetes-induced development of retinal vascular lesions characteristic of diabetic retinopathy, four groups of mice: wild type (WT) control mice, streptozotocin (STZ)-induced diabetic mice, LOX +/- mice, and STZ-induced diabetic LOX +/- mice were used for this study. Diabetes was maintained for 16 weeks; at the end of the study, retinas were assessed for LOX protein level by Western Blot (WB) analysis, and retinal capillary networks were isolated using retinal trypsin digestion and stained with hematoxylin and periodic acid Schiff to identify the number of acellular capillaries (AC) and pericyte loss (PL). In parallel, TUNEL assay was performed on retinal trypsin digests (RTDs) to detect cells undergoing apoptosis in the retinal capillary networks. Retinal vascular permeability was analyzed following FITC-dextran injection in retinal whole mounts. A significant increase in LOX expression was detected in the diabetic retinas compared to those of the WT control retinas, and as expected, a significant decrease in LOX expression in the diabetic LOX +/- retinas was observed compared to those of the diabetic retinas. RTD images showed significantly increased AC and PL counts in the retinas of diabetic mice compared to those of the WT control mice. Importantly, the number of AC and PL was significantly decreased, as was retinal vascular permeability in the retinas of the diabetic LOX +/- mice compared to those of the diabetic mice. Results suggest that decreasing diabetes-induced LOX overexpression may have protective effects against the development of vascular lesions characteristic of diabetic retinopathy. Therefore, LOX overexpression may be a potential target in preventing retinal vascular cell loss and excess permeability associated with diabetic retinopathy.
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Affiliation(s)
- Dongjoon Kim
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA
| | - Robert P Mecham
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Ngan-Ha Nguyen
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA
| | - Sayon Roy
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA.
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Chakravarthy H, Devanathan V. Molecular Mechanisms Mediating Diabetic Retinal Neurodegeneration: Potential Research Avenues and Therapeutic Targets. J Mol Neurosci 2018; 66:445-461. [PMID: 30293228 DOI: 10.1007/s12031-018-1188-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 09/25/2018] [Indexed: 12/16/2022]
Abstract
Diabetic retinopathy (DR) is a devastating complication of diabetes with a prevalence rate of 35%, and no effective treatment options. Since the most visible clinical features of DR are microvascular irregularities, therapeutic interventions often attempt to reduce microvascular injury, but only after permanent retinal damage has ensued. However, recent data suggests that diabetes initially affects retinal neurons, leading to neurodegeneration as an early occurrence in DR, before onset of the more noticeable vascular abnormalities. In this review, we delineate the sequence of initiating events leading to retinal degeneration in DR, considering neuronal dysfunction as a primary event. Key molecular mechanisms and potential biomarkers associated with retinal neuronal degeneration in diabetes are discussed. In addition to glial reactivity and inflammation in the diabetic retina, the contribution of neurotrophic factors, cell adhesion molecules, apoptosis markers, and G protein signaling to neurodegenerative pathways warrants further investigation. These studies could complement recent developments in innovative treatment strategies for diabetic retinopathy, such as targeting retinal neuroprotection, promoting neuronal regeneration, and attempts to re-program other retinal cell types into functional neurons. Indeed, several ongoing clinical trials are currently attempting treatment of retinal neurodegeneration by means of such novel therapeutic avenues. The aim of this article is to highlight the crucial role of neurodegeneration in early retinopathy progression, and to review the molecular basis of neuronal dysfunction as a first step toward developing early therapeutic interventions that can prevent permanent retinal damage in diabetes. ClinicalTrials.gov: NCT02471651, NCT01492400.
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Affiliation(s)
- Harshini Chakravarthy
- Department of Biology, Indian Institute of Science Education and Research (IISER), Transit campus: C/o. Sree Rama Engineering College Campus, Karakambadi Road, Mangalam, Tirupati, 517507, India
| | - Vasudharani Devanathan
- Department of Biology, Indian Institute of Science Education and Research (IISER), Transit campus: C/o. Sree Rama Engineering College Campus, Karakambadi Road, Mangalam, Tirupati, 517507, India.
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Haritoglou C, Maier M, Augustin A. Pathophysiology of diabetic macular edema – a background for current treatment modalities. EXPERT REVIEW OF OPHTHALMOLOGY 2018. [DOI: 10.1080/17469899.2018.1520634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
| | - Mathias Maier
- Department of Ophthalmology, Klinikum rechts der Isar, Technische Universität München, München, Germany
| | - Albert Augustin
- Department of Ophthalmology, Städtisches Klinikum Karlsruhe, Karlsruhe, Germany
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Dehdashtian E, Mehrzadi S, Yousefi B, Hosseinzadeh A, Reiter RJ, Safa M, Ghaznavi H, Naseripour M. Diabetic retinopathy pathogenesis and the ameliorating effects of melatonin; involvement of autophagy, inflammation and oxidative stress. Life Sci 2018; 193:20-33. [DOI: 10.1016/j.lfs.2017.12.001] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 11/19/2017] [Accepted: 12/01/2017] [Indexed: 12/12/2022]
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12
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Heat Shock Proteins in Vascular Diabetic Complications: Review and Future Perspective. Int J Mol Sci 2017; 18:ijms18122709. [PMID: 29240668 PMCID: PMC5751310 DOI: 10.3390/ijms18122709] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 12/09/2017] [Accepted: 12/11/2017] [Indexed: 01/22/2023] Open
Abstract
Heat shock proteins (HSPs) are a large family of proteins highly conserved throughout evolution because of their unique cytoprotective properties. Besides assisting protein refolding and regulating proteostasis under stressful conditions, HSPs also play an important role in protecting cells from oxidative stress, inflammation, and apoptosis. Therefore, HSPs are crucial in counteracting the deleterious effects of hyperglycemia in target organs of diabetes vascular complications. Changes in HSP expression have been demonstrated in diabetic complications and functionally related to hyperglycemia-induced cell injury. Moreover, associations between diabetic complications and altered circulating levels of both HSPs and anti-HSPs have been shown in clinical studies. HSPs thus represent an exciting therapeutic opportunity and might also be valuable as clinical biomarkers. However, this field of research is still in its infancy and further studies in both experimental diabetes and humans are required to gain a full understanding of HSP relevance. In this review, we summarize current knowledge and discuss future perspective.
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Lanatoside C, a cardiac glycoside, acts through protein kinase Cδ to cause apoptosis of human hepatocellular carcinoma cells. Sci Rep 2017; 7:46134. [PMID: 28387249 PMCID: PMC5384006 DOI: 10.1038/srep46134] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 03/13/2017] [Indexed: 01/21/2023] Open
Abstract
Recent studies have revealed that cardiac glycosides, such as digitalis and digoxin, have anticancer activity and may serve as lead compounds for the development of cancer treatments. The poor prognosis of hepatocellular carcinoma (HCC) patients reflects the development of resistance to current chemotherapeutic agents, highlighting the need for discovering new small-molecule therapeutics. Here, we found that lanatoside C, an anti-arrhythmic agent extracted from Digitalis lanata, inhibited the growth of HCC cells and dramatically decreased tumor volume as well as delayed tumor growth without obvious body weight loss. Moreover, lanatoside C triggered mitochondrial membrane potential (MMP) loss, activation of caspases and translocation of apoptosis-inducing factor (AIF) into the nucleus, which suggests that lanatoside C induced apoptosis through both caspase-dependent and -independent pathways. Furthermore, we discovered that lanatoside C activated protein kinase delta (PKCδ) via Thr505 phosphorylation and subsequent membrane translocation. Inhibition of PKCδ reversed lanatoside C-induced MMP loss and apoptosis, confirming that lanatoside C caused apoptosis through PKCδ activation. We also found that the AKT/mTOR pathway was negatively regulated by lanatoside C through PKCδ activation. In conclusion, we provide the first demonstration that the anticancer effects of lanatoside C are mainly attributable to PKCδ activation.
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Curcumin Attenuated Bupivacaine-Induced Neurotoxicity in SH-SY5Y Cells Via Activation of the Akt Signaling Pathway. Neurochem Res 2016; 41:2425-32. [PMID: 27233246 DOI: 10.1007/s11064-016-1955-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/06/2016] [Accepted: 05/11/2016] [Indexed: 10/21/2022]
Abstract
Bupivacaine is widely used for regional anesthesia, spinal anesthesia, and pain management. However, bupivacaine could cause neuronal injury. Curcumin, a low molecular weight polyphenol, has a variety of bioactivities and may exert neuroprotective effects against damage induced by some stimuli. In the present study, we tested whether curcumin could attenuate bupivacaine-induced neurotoxicity in SH-SY5Y cells. Cell injury was evaluated by examining cell viability, mitochondrial damage and apoptosis. We also investigated the levels of activation of the Akt signaling pathway and the effect of Akt inhibition by triciribine on cell injury following bupivacaine and curcumin treatment. Our findings showed that the bupivacaine treatment could induce neurotoxicity. Pretreatment of the SH-SY5Y cells with curcumin significantly attenuated bupivacaine-induced neurotoxicity. Interestingly, the curcumin treatment increased the levels of Akt phosphorylation. More significantly, the pharmacological inhibition of Akt abolished the cytoprotective effect of curcumin against bupivacaine-induced cell injury. Our data suggest that pretreating SH-SY5Y cells with curcumin provides a protective effect on bupivacaine-induced neuronal injury via activation of the Akt signaling pathway.
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Protective Effects of Melatonin on Retinal Inflammation and Oxidative Stress in Experimental Diabetic Retinopathy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:3528274. [PMID: 27143993 PMCID: PMC4837288 DOI: 10.1155/2016/3528274] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 12/11/2022]
Abstract
Oxidative stress and inflammation are important pathogenic factors contributing to the etiology of diabetic retinopathy (DR). Melatonin is an endogenous hormone that exhibits a variety of biological effects including antioxidant and anti-inflammatory functions. The goals of this study were to determine whether melatonin could ameliorate retinal injury and to explore the potential mechanisms. Diabetes was induced by a single intraperitoneal (i.p.) injection of STZ (60 mg/kg) in Sprague-Dawley rats. Melatonin (10 mg kg(-1) daily, i.p.) was administered from the induction of diabetes and continued for up to 12 weeks, after which the animals were sacrificed and retinal samples were collected. The retina of diabetic rats showed depletion of glutathione and downregulation of glutamate cysteine ligase (GCL). Melatonin significantly upregulated GCL by retaining Nrf2 in the nucleus and stimulating Akt phosphorylation. The production of proinflammatory cytokines and proteins, including interleukin 1β, TNF-α, and inducible nitric oxide synthase (iNOS), was inhibited by melatonin through the NF-κB pathway. At 12 weeks, melatonin prevented the significant decrease in the ERG a- and b-wave amplitudes under the diabetic condition. Our results suggest potent protective functions of melatonin in diabetic retinopathy. In addition to being a direct antioxidant, melatonin can exert receptor-mediated signaling effects to attenuate inflammation and oxidative stress of the retina.
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Wang LY, Li X, Han YZ. Neuroprotection by epigallo catechin gallate against bupivacaine anesthesia induced toxicity involves modulation of PI3/Akt/PTEN signalling in N2a and SH-SY5Y cells. Int J Clin Exp Med 2015; 8:15065-15075. [PMID: 26628990 PMCID: PMC4658879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/07/2015] [Indexed: 06/05/2023]
Abstract
Bupivacaine, an amide type long-acting local anaesthetic is commonly employed for epidural anesthesia and as well for nerve blockades. However, studies have shown neurotoxicity following local administration of bupivacaine raising concerns over the use of the drug. Compounds that could minimize or inhibit toxic effects of bupivacaine are of high value in operative settings and in pain management. The present study aims to investigate if epigallo catechin gallate (EGCG) could inhibit or prevent bupivacaine toxicity in neuroblastoma cells (N2a and SH-SY5Y). The viability of N2a and SH-SY5Y cells following exposure to EGCG (10-50 µM) were assessed by MTT assay and Annexin V/PI staining. The influence of EGCG on ROS generation was determined. The expression of apoptotic cascade proteins (Caspases-3, -8 and -9, Bcl-xL, Bad, Bax, Bcl-2) and PI3/Akt pathway proteins (Akt, p-Akt, GSK-3β, p-GSK-3β, PTEN) were analyzed by western blotting. EGCG improved the viability of the cells and inhibited apoptosis by potentially decreasing the expression of caspases and pro-apoptotic proteins. Bupivacaine induced ROS generations were reduced on EGCG exposure. EGCG significantly promoted the phosphorylation of Akt and GSK-3β and down-regulated PTEN, thus activating PI3/Akt signalling. EGCG effectively improved the cell viability and inhibited apoptosis of N2a and SH-SY5Y cells via suppression of ROS generation and modulation of PI3K/Akt signalling cascade.
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Affiliation(s)
- Li-Yan Wang
- Department of Pediatric Surgery, Linyi People's Hospital Linyi 276003, Shandong, China
| | - Xia Li
- Department of Pediatric Surgery, Linyi People's Hospital Linyi 276003, Shandong, China
| | - Yu-Zeng Han
- Department of Pediatric Surgery, Linyi People's Hospital Linyi 276003, Shandong, China
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Saccà SC, Pulliero A, Izzotti A. The Dysfunction of the Trabecular Meshwork During Glaucoma Course. J Cell Physiol 2014; 230:510-25. [DOI: 10.1002/jcp.24826] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 09/05/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Sergio Claudio Saccà
- Department of Head/Neck Pathologies; St Martino Hospital; Ophthalmology Unit; Genoa Italy
| | - Alessandra Pulliero
- Department of Health Sciences; Section of Hygiene and Preventive Medicine; University of Genoa; Genoa Italy
| | - Alberto Izzotti
- Department of Health Sciences; Section of Hygiene and Preventive Medicine; University of Genoa; Genoa Italy
- Mutagenesis Unit; IST National Institute for Cancer Research; IRCCS Hospital-University San Martino Company; Genoa Italy
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Kwon KJ, Lee EJ, Kim MK, Kim SY, Kim JN, Kim JO, Kim HJ, Kim HY, Han JS, Shin CY, Han SH. Diabetes augments cognitive dysfunction in chronic cerebral hypoperfusion by increasing neuronal cell death: implication of cilostazol for diabetes mellitus-induced dementia. Neurobiol Dis 2014; 73:12-23. [PMID: 25281785 DOI: 10.1016/j.nbd.2014.08.034] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/20/2014] [Accepted: 08/22/2014] [Indexed: 02/06/2023] Open
Abstract
Many patients with diabetes are at increased risk of cognitive dysfunction and dementia. Diabetes mellitus is a vascular risk factor that may increase the risk of dementia through its associations with vascular dementia. We tested whether cognitive impairment could be exacerbated in combined injury using a rat model of chronic cerebral hypoperfusion with diabetes. We also determined whether a potent inhibitor of type III phosphodiesterase could prevent the cognitive decline caused by this combined injury. We used Otsuka Long-Evans Tokushima Fatty (OLETF) rats as a model of type II diabetes (T2DM) and Long-Evans Tokushima Otsuka (LETO) rats as a control. Chronic cerebral hypoperfusion was modeled by permanent bilateral common carotid artery occlusion (BCCAO). At 24weeks, the non-diabetic and T2DM rats were randomly assigned into groups for the following experiments: analysis I (1) sham non-diabetic rats (n=8); (2) hypoperfused non-diabetic rats (n=9); (3) sham T2DM rats (n=8); (4) hypoperfused T2DM rats (n=9); analysis II- (1) sham T2DM rats without treatment (n=8); (2) cilostazol-treated T2DM rats (n=8); (3) hypoperfused T2DM rats (n=9); and (4) hypoperfused T2DM rats and cilostazol treatment (n=9). The rats were orally administered cilostazol (50mg/kg) or vehicle once a day for 2weeks after 24weeks. Rats performed Morris water maze tasks, and neuronal cell death and neuroinflammation were investigated via Western blots and histological investigation. Spatial memory impairment was exacerbated synergistically in the hypoperfused T2DM group compared with the hypoperfused non-diabetic group and sham T2DBM group (P<0.05). Compared with the control group, neuronal cell death was increased in the hippocampus of the hypoperfused T2DM group. Cilostazol, a PDE-3 inhibitor, improved the memory impairments through inhibition of neuronal cell death, activation of CREB phosphorylation and BDNF expression in the hypoperfused T2DM group. Our experimental results support the hypothesis that there are deleterious interactions between chronic cerebral hypoperfusion and T2DM. That is, metabolic diseases such as diabetes may exacerbate cognitive impairment in a rat model of vascular dementia. We also suggest that surprisingly, the phosphodiesterase III inhibitor, cilostazol may be useful for the treatment of cognitive impairment in diabetes mellitus-induced dementia. In conclusion, diabetes can aggravate cognitive dysfunction in vascular dementia, and PDE-3 inhibitors, such as cilostazol, may form the basis of a novel therapeutic strategy for diabetes-associated cognitive impairment or vascular dementia.
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Affiliation(s)
- Kyoung Ja Kwon
- Department of Neuroscience, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea
| | - Eun Joo Lee
- Department of Neuroscience, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea
| | - Min Kyeong Kim
- Department of Pharmacology, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea
| | - Soo Young Kim
- Department of Pharmacology, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea
| | - Jung Nam Kim
- Department of Pharmacology, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea
| | - Jin Ok Kim
- Department of Neuroscience, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea; Department of Neurology, Konkuk University Medical Center, 120-1 Neungdong-ro, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Hee-Jin Kim
- Department of Neurology, College of Medicine, Hanyang University, 17 Heangdang-dong, Seongdong-gu, Seoul, Republic of Korea
| | - Hahn Young Kim
- Department of Neuroscience, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea; Department of Neurology, Konkuk University Medical Center, 120-1 Neungdong-ro, Gwangjin-gu, Seoul 143-701, Republic of Korea
| | - Jung-Soo Han
- Department of Biological Sciences, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea
| | - Chan Young Shin
- Department of Pharmacology, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea
| | - Seol-Heui Han
- Department of Neuroscience, Center for Neuroscience Research, Institute of Biomedical Science and Technology, Konkuk University School of Medicine, Republic of Korea; Department of Neurology, Konkuk University Medical Center, 120-1 Neungdong-ro, Gwangjin-gu, Seoul 143-701, Republic of Korea.
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The effect of lithospermic acid, an antioxidant, on development of diabetic retinopathy in spontaneously obese diabetic rats. PLoS One 2014; 9:e98232. [PMID: 24905410 PMCID: PMC4048190 DOI: 10.1371/journal.pone.0098232] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 04/30/2014] [Indexed: 01/22/2023] Open
Abstract
Background Lithospermic acid B (LAB), an active component isolated from Salvia miltiorrhiza radix, has been reported to have antioxidant effects. We examined the effects of LAB on the prevention of diabetic retinopathy in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of type 2 diabetes. Methods and Findings LAB (10 or 20 mg/kg) or normal saline were given orally once daily to 24-week-old male OLETF rats for 52 weeks. At the end of treatment, fundoscopic findings, vascular endothelial growth factor (VEGF) expression in the eyeball, VEGF levels in the ocular fluid, and any structural abnormalities in the retina were assessed. Glucose metabolism, serum levels of high-sensitivity C-reactive protein (hsCRP), monocyte chemotactic protein-1 (MCP1), and tumor necrosis factor-alpha (TNFα) and urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels were also measured. Treatment with LAB prevented vascular leakage and basement membrane thickening in retinal capillaries in a dose-dependent manner. Insulin resistance and glucose intolerance were significantly improved by LAB treatment. The levels of serum hsCRP, MCP1, TNFα, and urinary 8-OHdG were lower in the LAB-treated OLETF rats than in the controls. Conclusions Treatment with LAB had a preventive effect on the development of diabetic retinopathy in this animal model, probably because of its antioxidative effects and anti-inflammatory effects.
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20
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Saccà SC, Izzotti A. Focus on molecular events in the anterior chamber leading to glaucoma. Cell Mol Life Sci 2014; 71:2197-218. [PMID: 24142347 PMCID: PMC11113507 DOI: 10.1007/s00018-013-1493-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 10/03/2013] [Accepted: 10/07/2013] [Indexed: 12/11/2022]
Abstract
Primary open-angle glaucoma is a multifactorial disease that affects the retinal ganglion cells, but currently its therapy is to lower the eye pressure. This indicates a definite involvement of the trabecular meshwork, key region in the pathogenesis of glaucoma. This is the first target of glaucoma, and its functional complexity is a real challenge to search. Its functions are those to allow the outflow of aqueous humor and not the reflux. This article describes the morphological and functional changes that happen in anterior chamber. The "primus movens" is oxidative stress that affects trabecular meshwork, particularly its endothelial cells. In these develops a real mitochondriopaty. This leads to functional impotence, the trabecular meshwork altering both motility and cytoarchitecture. Its cells die by apoptosis, losing barrier functions and altering the aqueous humor outflow. All the morphological alterations occur that can be observed under a microscope. Intraocular pressure rises and the malfunctioning trabecular meshwork endotelial cells express proteins that completely alter the aqueous humor. This is a liquid whose functional proteomics complies with the conditions of the trabecular meshwork. Indeed, in glaucoma, it is possible detect the presence of proteins which testify to what occurs in the anterior chamber. There are six classes of proteins which confirm the vascular endothelium nature of the anterior chamber and are the result of the morphofunctional trabecular meshwork decay. It is possible that, all or in part, these proteins can be used as a signal to the posterior pole.
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Affiliation(s)
- Sergio Claudio Saccà
- Ophthalmology Unit, Department of Head and Neck Pathologies, St Martino Hospital, Viale Benedetto XV, 16132, Genoa, Italy,
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21
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Zhang X, Zeng H, Bao S, Wang N, Gillies MC. Diabetic macular edema: new concepts in patho-physiology and treatment. Cell Biosci 2014; 4:27. [PMID: 24955234 PMCID: PMC4046142 DOI: 10.1186/2045-3701-4-27] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 04/22/2014] [Indexed: 12/22/2022] Open
Abstract
Diabetic macular edema (DME), a serious eye complication caused primarily by hyperglycemia, is one of the major causes of blindness. DME, which is characterized by cystic retinal thickening or lipid deposition, is prone to relapse after successful treatment. DME is a complex pathological process caused by multiple factors, including breakdown of the inner and outer blood-retinal barriers, oxidative stress, and elevated levels of vascular endothelial growth factor which have been demonstrated in both preclinical and clinical studies. Starling's law theory explains many of the features of DME. Early detection and treatment of DME can prevent vision loss. Current effective interventions for DME include treatment of systemic risk factors, such as elevated blood glucose, blood pressure and dyslipidemia. Ophthalmic treatments include laser photocoagulation, surgery and intraocular pharmacotherapy. New drugs, which are given by intraocular injection, have emerged in recent years to become first line treatment for DME that affects the central macula with loss of vision. Laser photocoagulation is still the gold standard of treatment for DME which does not involve the central macular. This review outlines these new treatments with particular emphasis on the optimal timing of how they are given.
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Affiliation(s)
- Xinyuan Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730 PR China ; Macula Research Group, Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
| | - Huan Zeng
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730 PR China
| | - Shian Bao
- Discipline of Pathology, School of Medical Sciences and Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing 100730 PR China
| | - Mark C Gillies
- Macula Research Group, Save Sight Institute, The University of Sydney, Sydney, NSW, Australia
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Park J, Kim H, Park SY, Lim SW, Kim YS, Lee DH, Roh GS, Kim HJ, Kang SS, Cho GJ, Jeong BY, Kwon HM, Choi WS. Tonicity-responsive enhancer binding protein regulates the expression of aldose reductase and protein kinase C δ in a mouse model of diabetic retinopathy. Exp Eye Res 2014; 122:13-9. [PMID: 24631337 DOI: 10.1016/j.exer.2014.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/24/2014] [Accepted: 03/02/2014] [Indexed: 12/25/2022]
Abstract
Recent studies revealed that Tonicity-responsive enhancer binding protein (TonEBP) directly regulates the transcription of aldose reductase (AR), which catalyzes the first step of the polyol pathway of glucose metabolism. Activation of protein kinase C δ (PKCδ) is dependent on AR and it has been linked to diabetic complications. However, whether TonEBP affects expressions of AR and PKCδ in diabetic retinopathy was not clearly shown. In this study, we used TonEBP heterozygote mice to study the role of TonEBP in streptozotocin (STZ)-induced diabetic retinopathy. We performed immunofluorescence staining and found that retinal expressions of AR and PKCδ were significantly reduced in the heterozygotes compared to wild type littermates, particularly in ganglion cell layer. To examine further the effect of TonEBP reduction in retinal tissues, we performed intravitreal injection of TonEBP siRNA and confirmed the decrease in AR and PKCδ levels. In addition, we found that a proapoptotic factor, Bax level was reduced and a survival factor, Bcl2 level was increased after injection of TonEBP siRNA, indicating that TonEBP mediates apoptotic cell death. In parallel, TonEBP siRNA was applied to the in vitro human retinal pigment epithelial (ARPE-19) cells cultured in high glucose media. We have consistently found the decrease in AR and PKCδ levels and changes in apoptotic factors for survival. Together, these results clearly demonstrated that hyperglycemia-induced TonEBP plays a crucial role in increasing AR and PKCδ levels and leading to apoptotic death. Our findings suggest that TonEBP reduction is an effective therapeutic strategy for diabetic retinopathy.
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Affiliation(s)
- Jeongsook Park
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea; Department of Food & Nutrition, College of Natural Sciences, Gyeongsang National University, Jinju, Gyeongnam, Republic of Korea
| | - Hwajin Kim
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - So Yun Park
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Sun Woo Lim
- Transplant Research Center, The of Catholic University of Korea, Seoul, Republic of Korea
| | - Yoon Sook Kim
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Dong Hoon Lee
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Gu Seob Roh
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Hyun Joon Kim
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Sang Soo Kang
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Gyeong Jae Cho
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea
| | - Bo-Young Jeong
- Department of Food & Nutrition, College of Natural Sciences, Gyeongsang National University, Jinju, Gyeongnam, Republic of Korea
| | - H Moo Kwon
- School of Nano-Biotechnology and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Wan Sung Choi
- Department of Anatomy and Neurobiology, Institute of Health Science, Medical Research Center for Neural Dysfunction, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, Republic of Korea.
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Klymenko K, Novokhatska T, Kizub I, Parshikov A, Dosenko V, Soloviev A. PKC-δ isozyme gene silencing restores vascular function in diabetic rat. J Basic Clin Physiol Pharmacol 2014; 25:1-9. [PMID: 24468620 DOI: 10.1515/jbcpp-2013-0147] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 12/11/2013] [Indexed: 11/15/2022]
Abstract
Abstract Background: Endothelium and K+ channel functionality in smooth muscle cells (SMCs) regulates vascular function and is exposed to damage in diabetes. The regulatory enzyme protein kinase C (PKC) is known to play a key role in vascular tone regulation in health and disease. In this study, we evaluated the effect of PKC-δ gene silencing using small interfering RNAs (siRNAs) on endothelial dysfunction and acquired potassium channelopathy in vascular SMCs in diabetes. Methods: The experimental design comprised diabetes induction by streptozotocin (65 mg/kg) in rats, RNA interference, isolated aortic ring contractile recordings, whole-cell patch-clamp technique, measurements of reactive oxygen species (ROS), and real-time polymerase chain reaction technique. Animals were killed by cervical dislocation following ketamine (45 mg/kg, i.p.) and xylazine (10 mg/kg, i.p.) anesthesia administration on the third month of diabetes and on the seventh day after intravenous injection of siRNAs. Results: The aortas of diabetic rats demonstrated depressed endothelium-dependent relaxation and integral SMCs outward K+ currents as compared with those of controls. On the seventh day, PKC-δ gene silencing effectively restored K+ currents and increased the amplitude of vascular relaxation up to control levels. An increased level of PKC-δ mRNA in diabetic aortas appeared to be reduced after targeted PKC-δ gene silencing. Similarly, the level of ROS production that was increased in diabetes came back to control values after siRNAs administration. Conclusions: The silencing of PKC-δ gene expression using siRNAs led to restoration of vasodilator potential in rats with diabetes mellitus. It is likely that the siRNA technique can be a good therapeutic tool to normalize vascular function in diabetes.
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Abstract
1-42 β-Amyloid (Aβ(1-42)) peptide is a key molecule involved in the development of Alzheimer's disease. Some of its effects are manifested at the neuronal morphological level. These morphological changes involve loss of neurites due to cytoskeleton alterations. However, the mechanism of Aβ(1-42) peptide activation of the neurodegenerative program is still poorly understood. Here, Aβ(1-42) peptide-induced transduction of cellular death signals through the phosphatidylinositol 3-kinase (PI3K)/phosphoinositol-dependent kinase (PDK)/novel protein kinase C (nPKC)/Rac 1 axis is described. Furthermore, pharmacological inhibition of PDK1 and nPKC activities blocks Rac 1 activation and neuronal cell death. Our results provide insights into an unsuspected connection between PDK1, nPKCs and Rac 1 in the same signal-transduction pathway and points out nPKCs and Rac 1 as potential therapeutic targets to block the toxic effects of Aβ(1-42) peptide in neurons.
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25
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Yang F, Cai W, Yang K, Chen M. PKCδ knockdown inhibits free fatty acid induction of endothelial cell apoptosis. Cell Biochem Funct 2012; 31:380-4. [PMID: 23086745 DOI: 10.1002/cbf.2908] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 08/16/2012] [Accepted: 09/10/2012] [Indexed: 11/11/2022]
Abstract
The mechanisms whereby free fatty acids induce endothelial cell apoptosis are not yet understood. The present study aimed to investigate the role of PKCδ in free fatty acid-induced endothelial cell apoptosis. In addition, we looked for evidence of apoptosis-related interactions between PKCδ and Fas signal pathway. Human umbilical vein endothelial cells were treated with various concentrations of free fatty acids and transiently transfected with PKCδ siRNA or Fas siRNA to inhibit PKCδ or Fas expression. Cell proliferation was determined through colorimetric assays, and apoptosis was quantified using flow cytometry. Protein expression was determined from cell lysates using Western blots with antibodies against p-PKCδTyr512, PKCδ, and Fas. Statistical analyses were performed. Free fatty acids had multiple effects on human umbilical vein endothelial cells, including concentration-dependent inhibition of cell proliferation, induction of apoptosis, increased Fas expression, and increased PKCδ expression and phosphorylation. Inhibition of PKCδ mRNA expression by PKCδ siRNA led to a reduction in both free fatty acid-induced apoptosis and Fas expression. However, Fas siRNA treatment inhibited Fas, but not PKCδ, expression in human umbilical vein endothelial cells. The free fatty acid-induced apoptosis in endothelial cells are possibly mediated by PKCδ and may involve upregulation of its downstream Fas.
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Affiliation(s)
- Feiyan Yang
- Department of Cardiology, The Central Hospital of Wuhan, Wuhan, Hubei Province, China, 430014
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Sun ZH, Xu XP, Song ZB, Zhang Z, Wang N, Guo QL. Repeated Intrathecal Administration of Ropivacaine Causes Neurotoxicity in Rats. Anaesth Intensive Care 2012; 40:825-31. [PMID: 22934865 DOI: 10.1177/0310057x1204000427] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Previous studies have shown that ropivacaine is the least neurotoxic local anaesthetic. Most of the data derive from short-term ropivacaine injection into the subarachnoid space. Intrathecal administration for a prolonged period, and the histological changes and behavioural effects of repeated intrathecal administration, have not previously been investigated. We studied the possible neurotoxicity of intrathecal injection of ropivacaine in a rat model. Rats received 0.12 ml/kg body weight of ropivacaine at concentrations of 0.5 or 1%, or normal saline only, via an implanted intrathecal catheter at 90-minute intervals for 12 hours. On days 1, 3, 5, 7, 14 and 28, the spinal cord was examined by light and electron microscopy at the L3 level. We assessed sensory thresholds to noxious stimulation, behavioural change and protein kinase B immunoreactivity for possible neuronal injury within the spinal cord. Ropivacaine 1% induced thermal hyperalgesia and mechanical allodynia, neuronal injury characterised by tissue oedema, proliferation of glial cells, neuronal morphology changes and degeneration and protein kinase B expression. There were no significant differences in motor function as a result of different concentrations of ropivacaine. Repeated intrathecal injection of ropivacaine 1% can induce neurotoxicity in rats. Our data suggests that expression of protein kinase B might be involved in this neurotoxicity.
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Affiliation(s)
- Z. H. Sun
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - X. P. Xu
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Z. B. Song
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Z. Zhang
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - N. Wang
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Q. L. Guo
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan, China
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Yang Y, Mao D, Chen X, Zhao L, Tian Q, Liu C, Zhou BLS. Decrease in retinal neuronal cells in streptozotocin-induced diabetic mice. Mol Vis 2012; 18:1411-20. [PMID: 22690119 PMCID: PMC3369894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 05/29/2012] [Indexed: 10/24/2022] Open
Abstract
PURPOSE Little is known about retinal neuronal loss in the retinas of diabetic mice. The purpose of this study was the quantitative assessment of retinal neural cell number in diabetic mice. METHODS Five-week-old C57BL/6 mice were used as a diabetic model with streptozotocin. Mice were studied over the course of 6 and 12 weeks after the onset of diabetes. Intraocular pressure (IOP) was measured with a noninvasive TonoLab tonometer. The retinal ganglion cells (RGCs) were counted at two different time points after the induction of diabetes and examined using the immunofluorescence technique and quantitative analysis. RESULTS The diabetic mice had significantly elevated IOP levels at 6 and 12 weeks after the onset of diabetes compared with the age-matched control mice (p<0.01 and p<0.001, respectively). The temporal course of Brn3a+ RGC and Neuronal Nuclei+RGC (NeuN+ RGC) loss induced by intraperitoneal injection of streptozotocin followed a similar trend. At 6 and 12 weeks after the onset of diabetes, the number of Brn3a+ RGCs (p<0.05 at 6 weeks; p<0.001 at 12 weeks) and NeuN+ RGCs (p<0.05 at 6 weeks; p<0.001 at 12 weeks) was significantly lower in diabetic mice than age-matched control mice. In the retinal flatmounts, the number of Brn3a+ RGCs (p<0.05 at 6 weeks, p<0.01 at 12 weeks) was also significantly lower in diabetic mice than control mice. The IOP in diabetic mice was negatively related with RGCs in cross sections. The cut-off value of IOP was 14.2 mmHg for diabetes. CONCLUSIONS This is a specific quantitative study of neural cell loss in the retina during diabetes. These data suggest that retinal neural cell reduction occurs in diabetic mice. It indicates that RGC loss may be an important component of diabetic retinopathy.
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Mima A, Kitada M, Geraldes P, Li Q, Matsumoto M, Mizutani K, Qi W, Li C, Leitges M, Rask-Madsen C, King GL. Glomerular VEGF resistance induced by PKCδ/SHP-1 activation and contribution to diabetic nephropathy. FASEB J 2012; 26:2963-74. [PMID: 22499584 DOI: 10.1096/fj.11-202994] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
This study characterizes the effect of glucose-induced activation of protein kinase Cδ (PKCδ) and Src homology-2 domain-containing phosphatase-1 (SHP-1) expression on vascular endothelial growth factor (VEGF) actions in glomerular podocytes in cultures and in glomeruli of diabetic rodents. Elevation of glucose levels induced PKCδ and p38 mitogen-activated protein kinase (p38 MAPK) to increase SHP-1 expression, increased podocyte apoptosis, and inhibited VEGF activation in podocytes and glomerular endothelial cells. The adverse effects of high glucose levels can be negated by molecular inhibitors of PKCδ, p38MAPK, and SHP-1 and only partially reduced by antioxidants and nuclear factor-κB (NF-κB) inhibitor. Increased PKCδ activation and SHP-1 expression correlated with loss of VEGF signaling and podocyte numbers in the glomeruli of diabetic rats and mice. In contrast, diabetic PKCδ-knockout (Prkcd(-/-)) mice did not exhibit activation of p38 MAPK and SHP-1 or inhibition of VEGF signaling in renal glomeruli. Functionally, diabetic Prkcd(-/-) mice had decreased expressions of TGFβ, VEGF, and extracellular matrix and less albuminuria than diabetic Prkcd(+/+) mice. Hyperglycemia and diabetes can cause glomerular podocyte apoptosis and endothelial dysfunction partly due to increased PKCδ/p38 MAPK activation and the expression of SHP-1 to cause VEGF resistance, independent of NF-κB activation.
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Affiliation(s)
- Akira Mima
- Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts, USA
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29
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Kim YH, Kim YS, Roh GS, Choi WS, Cho GJ. Resveratrol blocks diabetes-induced early vascular lesions and vascular endothelial growth factor induction in mouse retinas. Acta Ophthalmol 2012; 90:e31-7. [PMID: 21914146 DOI: 10.1111/j.1755-3768.2011.02243.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
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.
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Affiliation(s)
- Young Hee Kim
- Department of Anatomy and Neurobiology, School of Medicine, BK21 Biomedical Center, Gyeongsang National University, Jinju, Korea
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30
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Wang Z, Shen J, Wang J, Lu T, Li C, Zhang X, Liu L, Ding Z. Lithium attenuates bupivacaine-induced neurotoxicity in vitro through phosphatidylinositol-3-kinase/threonine-serine protein kinase B- and extracellular signal-regulated kinase-dependent mechanisms. Neuroscience 2012; 206:190-200. [PMID: 22233781 DOI: 10.1016/j.neuroscience.2011.12.043] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 11/28/2011] [Accepted: 12/19/2011] [Indexed: 11/27/2022]
Abstract
Local anesthetics (LAs) are necessary for the regional anesthesia, spinal anesthesia, and pain management. However, the application of LAs may cause neurotoxicity and result in postoperative neurological complications. Lithium is a mood stabilizer for the treatment of bipolar disorder and may exert neuroprotective effects. In this study, we evaluated the effects of lithium on bupivacaine (a frequently used LAs)-induced injury in mouse neuroblastoma neuro 2a (N2a) cells. N2a cells were treated with bupivacaine in the presence or absence of lithium. After treatment, the cell injury was evaluated by examination of viability, morphology changes, and nuclear condensation. The levels of mitochondrial transmembrane potential (ΔΨm) and activation of phosphatidylinositol-3-kinase (PI3K)/ threonine-serine protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) were also examined. In a separate experiment, we investigated the effect of Akt and ERK inhibition on cell injury after bupivacaine and lithium treatment. Pretreatment of N2a cells with lithium significantly attenuated bupivacaine-induced cell injury. Lithium pretreatment completely reversed the suppression of PI3K/Akt and ERK signalings and significantly prevented the decline of ΔΨm in N2a cells after bupivacaine treatment. More importantly, pharmacological inhibition of Akt and ERK diminished the protective effect of lithium against bupivacaine-induced neuronal death. Our data suggest that lithium pretreatment provides a protective effect on bupivacaine-induced neuronal cell injury. This action of lithium is mediated through, at least in part, the activating of PI3K/Akt- and ERK-dependent mechanisms. Because lithium is a clinically proved safety drug for neurons, it is worthwhile to identify whether coadministration of LAs with lithium will decrease the risks of LAs-induced postoperative neurological complications in clinic practice.
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Affiliation(s)
- Z Wang
- Department of Geriatrics, First Affiliated Hospital with Nanjing Medical University, Nanjing, China
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Fort PE, Losiewicz MK, Reiter CEN, Singh RSJ, Nakamura M, Abcouwer SF, Barber AJ, Gardner TW. Differential roles of hyperglycemia and hypoinsulinemia in diabetes induced retinal cell death: evidence for retinal insulin resistance. PLoS One 2011; 6:e26498. [PMID: 22046295 PMCID: PMC3202547 DOI: 10.1371/journal.pone.0026498] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 09/27/2011] [Indexed: 01/10/2023] Open
Abstract
Diabetes pathology derives from the combination of hyperglycemia and hypoinsulinemia or insulin resistance leading to diabetic complications including diabetic neuropathy, nephropathy and retinopathy. Diabetic retinopathy is characterized by numerous retinal defects affecting the vasculature and the neuro-retina, but the relative contributions of the loss of retinal insulin signaling and hyperglycemia have never been directly compared. In this study we tested the hypothesis that increased retinal insulin signaling and glycemic normalization would exert differential effects on retinal cell survival and retinal physiology during diabetes. We have demonstrated in this study that both subconjunctival insulin administration and systemic glycemic reduction using the sodium-glucose linked transporter inhibitor phloridzin affected the regulation of retinal cell survival in diabetic rats. Both treatments partially restored the retinal insulin signaling without increasing plasma insulin levels. Retinal transcriptomic and histological analysis also clearly demonstrated that local administration of insulin and systemic glycemia normalization use different pathways to counteract the effects of diabetes on the retina. While local insulin primarily affected inflammation-associated pathways, systemic glycemic control affected pathways involved in the regulation of cell signaling and metabolism. These results suggest that hyperglycemia induces resistance to growth factor action in the retina and clearly demonstrate that both restoration of glycemic control and retinal insulin signaling can act through different pathways to both normalize diabetes-induced retinal abnormality and prevent vision loss.
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Affiliation(s)
- Patrice E Fort
- Kellogg Eye Center, University of Michigan, Ophthalmology and Visual Sciences Department, Ann Arbor, Michigan, United States of America.
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Sivaswamy S, Neafsey EJ, Collins MA. Neuroprotective preconditioning of rat brain cultures with ethanol: potential transduction by PKC isoforms and focal adhesion kinase upstream of increases in effector heat shock proteins. Eur J Neurosci 2010; 32:1800-12. [DOI: 10.1111/j.1460-9568.2010.07451.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Lee HG, Yang JH. PKC-δ mediates TCDD-induced apoptosis of chondrocyte in ROS-dependent manner. CHEMOSPHERE 2010; 81:1039-1044. [PMID: 20846705 DOI: 10.1016/j.chemosphere.2010.08.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 08/19/2010] [Accepted: 08/22/2010] [Indexed: 05/29/2023]
Abstract
Exposure to dioxin-like compounds is associated with arthritis in humans. A recent study reported that 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD) induces apoptosis in chondrocytes, which is a critical event in the pathogenesis of cartilage disease. In this study, protein kinase C (PKC) signaling pathway was investigated to determine the mechanism of TCDD-induced rabbit articular chondrocyte apoptosis. TCDD exposure induced glutathione-mediated ROS generation and the translocation of PKC isozymes. Among the PKC isozymes tested, PKC-δ showed the most sensitive translocation. The translocation was then blocked by ROS inhibitors (trolox and N-acetyl cysteine), a PKC-δ inhibitor (rottlerin), a caspase-3 inhibitor (z-DEVD-fmk) or an AhR blocker (α-naphthoflavone). TCDD increased caspase-3 activity, the activating enzyme for PKC-δ, and prior treatment with trolox blocked such an increase. These results suggest that the translocation of PKC-δ was mediated by ROS-dependent caspase-3 activity. Pretreatment with rottlerin or trolox dampened TCDD-induced apoptosis of chondrocyte, as determined by TUNEL staining and ELISA. Taken together, this study suggests that ROS generation is an upstream event for TCDD-induced chondrocyte apoptosis and PKC-δ mediates the apoptotic processes through ROS-dependent caspase-3 activation. This is a first finding demonstrating the role of PKC-δ in chondrocyte apoptosis stimulated by an environmental pollutant. The results may contribute to understanding the mechanism of joint disease associated with the exposure of dioxin-like compounds and identifying a target for the therapeutic interventions.
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Affiliation(s)
- Hyun-Gyo Lee
- Department of Pharmacology, School of Medicine, Catholic University of Daegu, Republic of Korea
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Amadio M, Bucolo C, Leggio GM, Drago F, Govoni S, Pascale A. The PKCbeta/HuR/VEGF pathway in diabetic retinopathy. Biochem Pharmacol 2010; 80:1230-7. [PMID: 20599775 DOI: 10.1016/j.bcp.2010.06.033] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 06/21/2010] [Accepted: 06/21/2010] [Indexed: 01/01/2023]
Abstract
We investigated whether the diabetes-related PKCbeta activation affects VEGF expression through the mRNA-stabilizing human embryonic lethal abnormal vision (ELAV) protein, HuR, in the retina of streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in rats by STZ injection. Retinal tissues were processed to detect PKCbetaI, PKCbetaII, VEGF and HuR contents, as well as HuR phosphorylation. Immunoprecipitation coupled to RT-PCR was employed to evaluate HuR binding to VEGF mRNA in RiboNucleoProteic (RNP) complexes. Statistical analysis was performed by ANOVA followed by an appropriate post hoc comparison test. Following experimental diabetes PKCbetaI and PKCbetaII levels were increased compared to sham; there was also a PKC-mediated phosphorylation/activation of HuR. These effects were blunted by the in vivo co-administration of a selective PKCbeta inhibitor. A specific binding between the HuR protein and the VEGF mRNA was also detected. The PKCbeta/HuR activation was accompanied by enhanced VEGF protein expression that was, again, blunted by the PKCbeta inhibitor. These findings first demonstrate the activation, in the retina, of the PKCbeta/HuR/VEGF pathway following experimental diabetes and disclose a new potential pharmacological target to counteract pathologies implicating VEGF deregulation, such as diabetic retinopathy.
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Affiliation(s)
- M Amadio
- Department of Experimental and Applied Pharmacology, Centre of Excellence in Applied Biology, University of Pavia, Pavia, Italy
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Kim YH, Kim YS, Kang SS, Cho GJ, Choi WS. Resveratrol inhibits neuronal apoptosis and elevated Ca2+/calmodulin-dependent protein kinase II activity in diabetic mouse retina. Diabetes 2010; 59:1825-35. [PMID: 20424226 PMCID: PMC2889785 DOI: 10.2337/db09-1431] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE This study investigated the effects of resveratrol, a natural polyphenol with neuroprotective properties, on retinal neuronal cell death mediated by diabetes-induced activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). RESEARCH DESIGN AND METHODS Diabetes was induced in C57BL/6 mice by five consecutive intraperitoneal injections of 55 mg/kg streptozotocin (STZ). Control mice received buffer. All mice were killed 2 months after the injections, and the extent of neuronal cell death, CaMKII, and phospho-CaMKII protein expression levels and CaMKII kinase activity were examined in the retinas. To assess the role of CaMKII in the death of retinal neurons, a small-interfering RNA (siRNA) or specific inhibitor of CaMKII was injected into the right vitreous humor, and vehicle only was injected into the left vitreous humor, 2 days before death. Resveratrol (20 mg/kg) was administered by oral gavage daily for 4 weeks, beginning 1 month after the fifth injection of either STZ or buffer. RESULTS The death of retinal ganglion cells (RGCs), CaMKII, phospho-CaMKII protein levels, and CaMKII activity were all greatly increased in the retinas of diabetic mice compared with controls, 2 months after induction of diabetes. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL)-positive signals co-localized with CaMKII- and phospho-CaMKII immunoreactive RGCs. However, in addition to CaMKII knockdown and inhibition by siRNA or a specific inhibitor, respectively, resveratrol provided complete protection from diabetes-induced retinal cell death. CONCLUSIONS In the present study, resveratrol prevented diabetes-induced RGC death via CaMKII downregulation, implying that resveratrol may have potential therapeutic applications for prevention of diabetes-induced visual dysfunction.
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Affiliation(s)
- Young-Hee Kim
- From the Department of Anatomy and Neurobiology, Gyeongsang National University, Jinju, Gyeongnam, Korea
| | - Yoon-Sook Kim
- From the Department of Anatomy and Neurobiology, Gyeongsang National University, Jinju, Gyeongnam, Korea
| | - Sang-Soo Kang
- From the Department of Anatomy and Neurobiology, Gyeongsang National University, Jinju, Gyeongnam, Korea
| | - Gyeong-Jae Cho
- From the Department of Anatomy and Neurobiology, Gyeongsang National University, Jinju, Gyeongnam, Korea
| | - Wan-Sung Choi
- From the Department of Anatomy and Neurobiology, Gyeongsang National University, Jinju, Gyeongnam, Korea
- Corresponding author: Wan Sung Choi,
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Ma R, Wang X, Lu C, Li C, Cheng Y, Ding G, Liu L, Ding Z. Dexamethasone attenuated bupivacaine-induced neuron injury in vitro through a threonine–serine protein kinase B-dependent mechanism. Neuroscience 2010; 167:329-42. [DOI: 10.1016/j.neuroscience.2009.12.049] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 12/18/2009] [Accepted: 12/22/2009] [Indexed: 01/24/2023]
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Application of proteomics to neutrophil biology. J Proteomics 2009; 73:552-61. [PMID: 19580889 DOI: 10.1016/j.jprot.2009.06.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 06/23/2009] [Accepted: 06/28/2009] [Indexed: 01/13/2023]
Abstract
Polymorphonuclear leukocytes or neutrophils are a primary effector cell of the innate immune system and contribute to the development of adaptive immunity. Neutrophils participate in both the initiation and resolution of inflammatory responses through a series of highly coordinated molecular and phenotypic changes. To accomplish these changes, neutrophils express numerous receptors and use multiple overlapping and redundant signal transduction pathways. Dysregulation of the activation or resolution pathways plays a role in a number of human diseases. A comprehensive understanding of the regulation of neutrophil responses can be provided by high throughput proteomic technologies and sophisticated computational analysis. The first steps in the application of proteomics to understanding neutrophil biology have been taken. Here we review the application of expression, structural, and functional proteomic studies to neutrophils. Although defining the complex molecular events associated with neutrophil activation is in the early stages, the data generated to date suggest that proteomic technologies will dramatically enhance our understanding of neutrophil biology.
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Current literature in diabetes. Diabetes Metab Res Rev 2009; 25:i-x. [PMID: 19219862 DOI: 10.1002/dmrr.918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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