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Hwang S, Seong M, Kang MH, Thng ZX, Cho H, Shin YU. Association of a Bioimpedance Profile with Optical Coherence Tomography Features in Diabetic Macular Edema. J Clin Med 2023; 12:6676. [PMID: 37892814 PMCID: PMC10607216 DOI: 10.3390/jcm12206676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/16/2023] [Accepted: 10/20/2023] [Indexed: 10/29/2023] Open
Abstract
We examined the association between bioimpedance profiles and optical coherence tomography (OCT) features in patients with diabetic macular edema (DME). This cross-sectional study included 100 eyes of 100 patients with type 2 diabetes mellitus. The systemic fluid status was assessed using extracellular water-to-total body water ratio (ECW/TBW) and phase angle (PhA), which was measured using bioimpedance equipment. ECW/TBW was higher in the DR (diabetic retinopathy) with DME group than in the no DR and DR without DME groups (p = 0.007 and p = 0.047, respectively); however, no significant difference was observed between the no DR and DR without DME groups. The PhA values were significantly lower in the DR with DME group (5.45 ± 0.84) than in the no DR (6.69 ± 0.69) and DR without DME groups (6.05 ± 1.15) (p < 0.001, p = 0.032, respectively). The presence of multiple HRF (hyper-reflective foci) was associated with a significantly higher ECW/TBW (p = 0.001). In the group with the most significant HRF, PhA was lower than in those with none or moderate amounts of HRF (p < 0.05). Bioimpedance fluid profiles of patients with OCT features of DME suggest a connection between the overall systemic state, including fluid status and DME development. Further research is required to fully understand and utilize this information for effective clinical assessment and treatment planning.
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Affiliation(s)
- Sunjin Hwang
- Department of Ophthalmology, Hanyang University Guri Hospital, Hanyang University College of Medicine, Seoul 04763, Republic of Korea; (S.H.); (M.S.); (M.H.K.)
| | - Mincheol Seong
- Department of Ophthalmology, Hanyang University Guri Hospital, Hanyang University College of Medicine, Seoul 04763, Republic of Korea; (S.H.); (M.S.); (M.H.K.)
| | - Min Ho Kang
- Department of Ophthalmology, Hanyang University Guri Hospital, Hanyang University College of Medicine, Seoul 04763, Republic of Korea; (S.H.); (M.S.); (M.H.K.)
| | - Zheng Xian Thng
- Byers Eye Institute, Stanford University, Palo Alto, CA 94305, USA;
- National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore 308433, Singapore
| | - Heeyoon Cho
- Department of Ophthalmology, Hanyang University Guri Hospital, Hanyang University College of Medicine, Seoul 04763, Republic of Korea; (S.H.); (M.S.); (M.H.K.)
| | - Yong Un Shin
- Department of Ophthalmology, Hanyang University Guri Hospital, Hanyang University College of Medicine, Seoul 04763, Republic of Korea; (S.H.); (M.S.); (M.H.K.)
- Byers Eye Institute, Stanford University, Palo Alto, CA 94305, USA;
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Bora K, Kushwah N, Maurya M, Pavlovich MC, Wang Z, Chen J. Assessment of Inner Blood-Retinal Barrier: Animal Models and Methods. Cells 2023; 12:2443. [PMID: 37887287 PMCID: PMC10605292 DOI: 10.3390/cells12202443] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/07/2023] [Accepted: 10/08/2023] [Indexed: 10/28/2023] Open
Abstract
Proper functioning of the neural retina relies on the unique retinal environment regulated by the blood-retinal barrier (BRB), which restricts the passage of solutes, fluids, and toxic substances. BRB impairment occurs in many retinal vascular diseases and the breakdown of BRB significantly contributes to disease pathology. Understanding the different molecular constituents and signaling pathways involved in BRB development and maintenance is therefore crucial in developing treatment modalities. This review summarizes the major molecular signaling pathways involved in inner BRB (iBRB) formation and maintenance, and representative animal models of eye diseases with retinal vascular leakage. Studies on Wnt/β-catenin signaling are highlighted, which is critical for retinal and brain vascular angiogenesis and barriergenesis. Moreover, multiple in vivo and in vitro methods for the detection and analysis of vascular leakage are described, along with their advantages and limitations. These pre-clinical animal models and methods for assessing iBRB provide valuable experimental tools in delineating the molecular mechanisms of retinal vascular diseases and evaluating therapeutic drugs.
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Affiliation(s)
| | | | | | | | | | - Jing Chen
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
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3
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Shome A, Mugisho OO, Niederer RL, Rupenthal ID. Comprehensive Grading System for Experimental Autoimmune Uveitis in Mice. Biomedicines 2023; 11:2022. [PMID: 37509662 PMCID: PMC10377264 DOI: 10.3390/biomedicines11072022] [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: 05/22/2023] [Revised: 06/22/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
Experimental autoimmune uveitis (EAU) is the most commonly used animal model to study the progression of chronic uveitis and to test various therapies to treat the disease. However, to accurately evaluate the effectiveness of such treatments, a grading system that combines the latest imaging techniques with definitive quantitative grading thresholds is required. This study aimed to develop a comprehensive grading system that objectively evaluates EAU progression in C57BL/6J mice. EAU was induced following immunisation with interphotoreceptor retinoid-binding protein (IRBP) and pertussis toxin. Weekly fundus and optical coherence tomography (OCT) images were acquired over 12 weeks using a Micron IV imaging system. Each mouse was graded (between 0 to 4) based on changes seen on both the fundus (optic disc, retinal blood vessels and retinal tissue) and OCT (vitreous and retinal layers) images. A total EAU response (with a maximum score of 48) was calculated for each mouse based on the sum of the individual scores each week. Analysis of the clinical scores depicted a gradual increase in inflammatory signs including optic disc and vascular swelling, leukocyte infiltration in the vitreous, lesions in the retina and formation of granulomas and hyper-reflective foci in the retinal layers in EAU mice, with most signs reaching a plateau towards the end of the study period. Development of these signs into sight-threatening complications such as optic disc atrophy, structural damage to the retina and subretinal oedema were noted in 80-90% of mice suggesting consistent disease induction. Overall, a comprehensive and objective grading system encompassing all pathologies occurring in EAU mice was developed to enhance the preclinical evaluation of novel uveitis treatments.
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Affiliation(s)
- Avik Shome
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, The New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand
| | - Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, The New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand
| | - Rachael L Niederer
- Department of Ophthalmology, The New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand
- Te Whatu Ora Te Toka Tumai, Auckland 1142, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, The New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand
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Mugisho OO, Aryal J, Shome A, Lyon H, Acosta ML, Green CR, Rupenthal ID. Orally Delivered Connexin43 Hemichannel Blocker, Tonabersat, Inhibits Vascular Breakdown and Inflammasome Activation in a Mouse Model of Diabetic Retinopathy. Int J Mol Sci 2023; 24:3876. [PMID: 36835288 PMCID: PMC9961562 DOI: 10.3390/ijms24043876] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Diabetic retinopathy (DR), a microvascular complication of diabetes, is associated with pronounced inflammation arising from the activation of a nucleotide-binding and oligomerization domain-like receptor (NLR) protein 3 (NLRP3) inflammasome. Cell culture models have shown that a connexin43 hemichannel blocker can prevent inflammasome activation in DR. The aim of this study was to evaluate the ocular safety and efficacy of tonabersat, an orally bioavailable connexin43 hemichannel blocker, to protect against DR signs in an inflammatory non-obese diabetic (NOD) DR mouse model. For retina safety studies, tonabersat was applied to retinal pigment epithelial (ARPE-19) cells or given orally to control NOD mice in the absence of any other stimuli. For efficacy studies, either tonabersat or a vehicle was given orally to the inflammatory NOD mouse model two hours before an intravitreal injection of pro-inflammatory cytokines, interleukin-1 beta, and tumour necrosis factor-alpha. Fundus and optical coherence tomography images were acquired at the baseline as well as at 2- and 7-day timepoints to assess microvascular abnormalities and sub-retinal fluid accumulation. Retinal inflammation and inflammasome activation were also assessed using immunohistochemistry. Tonabersat did not have any effect on ARPE-19 cells or control NOD mouse retinas in the absence of other stimuli. However, the tonabersat treatment in the inflammatory NOD mice significantly reduced macrovascular abnormalities, hyperreflective foci, sub-retinal fluid accumulation, vascular leak, inflammation, and inflammasome activation. These findings suggest that tonabersat may be a safe and effective treatment for DR.
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Affiliation(s)
- Odunayo O. Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Jyoti Aryal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Avik Shome
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Heather Lyon
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Monica L. Acosta
- School of Optometry and Vision Science, University of Auckland, Auckland 1023, New Zealand;
| | - Colin R. Green
- Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand
| | - Ilva D. Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
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Rodent Models of Diabetic Retinopathy as a Useful Research Tool to Study Neurovascular Cross-Talk. BIOLOGY 2023; 12:biology12020262. [PMID: 36829539 PMCID: PMC9952991 DOI: 10.3390/biology12020262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023]
Abstract
Diabetes is a group of metabolic diseases leading to dysfunction of various organs, including ocular complications such as diabetic retinopathy (DR). Nowadays, DR treatments involve invasive options and are applied at the sight-threatening stages of DR. It is important to investigate noninvasive or pharmacological methods enabling the disease to be controlled at the early stage or to prevent ocular complications. Animal models are useful in DR laboratory practice, and this review is dedicated to them. The first part describes the characteristics of the most commonly used genetic rodent models in DR research. The second part focuses on the main chemically induced models. The authors pay particular attention to the streptozotocin model. Moreover, this section is enriched with practical aspects and contains the current protocols used in research in the last three years. Both parts include suggestions on which aspect of DR can be tested using a given model and the disadvantages of each model. Although animal models show huge variability, they are still an important and irreplaceable research tool. Note that the choice of a research model should be thoroughly considered and dependent on the aspect of the disease to be analyzed.
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Martis RM, Knight LJ, Acosta ML, Black J, Ng R, Ji LCL, Donaldson PJ, Lim JCH. Early onset of age-related changes in the retina of cystine/glutamate antiporter knockout mice. Exp Eye Res 2023; 227:109364. [PMID: 36586548 DOI: 10.1016/j.exer.2022.109364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/13/2022] [Accepted: 12/20/2022] [Indexed: 12/29/2022]
Abstract
To determine the role of the cystine/glutamate antiporter on retinal structure and function, retinas of C57Bl/6J wild-type and xCT knockout mice, lacking the xCT subunit of the cystine/glutamate antiporter were examined from 6 weeks to 12 months of age. Fundoscopy, optical coherence tomography (OCT), and whole mount retinal autofluorescence imaging were used to visualise age-related retinal spots. Glial fibrillary acidic protein (GFAP) immunolabelling was used to assess retinal stress. Retinal function was evaluated using full-field and focal electroretinograms. Examinations revealed retinal spots in both wild-type and xCT knockout mice with the number of spots greater at 9 months in the knockout compared to wild-type. OCT confirmed these discrete spots were located at the retinal pigment epithelium (RPE)-photoreceptor junction and did not label with drusen markers. Whole mount lambda scans of the 9 month xCT knockout retinas revealed that the photoreceptor autofluorescence matched the spots, suggesting these spots were retinal debris. GFAP labelling was increased in knockout retinas compared to wild-type indicative of retinal stress, and the discrete spots were associated with migration of microglia/macrophages to the RPE-retina intersection. OCT revealed that the superior retina was thinner at 9 months in knockout compared to wild-type mice due to changes to the outer nuclear and photoreceptor layers. While global retinal function was not affected by loss of xCT, focal changes in retinal function were detected in areas where spots were present. Tother these results suggest that the xCT KO mice exhibit features of accelerated ageing and suggests that this mouse model may be useful for studying the underlying cellular pathways in retinal ageing.
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Affiliation(s)
- Renita Maria Martis
- Dept. Physiology, School of Medical Sciences, University of Auckland, New Zealand; School of Optometry and Vision Science, University of Auckland, New Zealand; New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Luis James Knight
- Dept. Physiology, School of Medical Sciences, University of Auckland, New Zealand; New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science, University of Auckland, New Zealand; New Zealand National Eye Centre, University of Auckland, New Zealand; Centre for Brain Research, University of Auckland, New Zealand
| | - Joanna Black
- School of Optometry and Vision Science, University of Auckland, New Zealand; New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Robert Ng
- School of Optometry and Vision Science, University of Auckland, New Zealand; New Zealand National Eye Centre, University of Auckland, New Zealand
| | | | - Paul James Donaldson
- Dept. Physiology, School of Medical Sciences, University of Auckland, New Zealand; New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Julie Ching-Hsia Lim
- Dept. Physiology, School of Medical Sciences, University of Auckland, New Zealand; New Zealand National Eye Centre, University of Auckland, New Zealand.
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Proinflammatory Cytokines Trigger the Onset of Retinal Abnormalities and Metabolic Dysregulation in a Hyperglycemic Mouse Model. J Ophthalmol 2023; 2023:7893104. [PMID: 36895267 PMCID: PMC9991478 DOI: 10.1155/2023/7893104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/22/2023] [Accepted: 02/03/2023] [Indexed: 03/06/2023] Open
Abstract
Purpose Recent evidence has shown that retinal inflammation is a key player in diabetic retinopathy (DR) pathogenesis. To further understand and validate the metabolic biomarkers of DR, we investigated the effect of intravitreal proinflammatory cytokines on the retinal structure, function, and metabolism in an in vivo hyperglycemic mouse model. Methods C57Bl/6 mice were rendered hyperglycemic within one week of administration of a single high-dose intraperitoneal injection of streptozotocin, while control mice received vehicle injection. After confirming hyperglycemia, the mice received an intravitreal injection of either proinflammatory cytokines (TNF-α and IL-1β) or vehicle. Similarly, control mice received an intravitreal injection of either proinflammatory cytokines or vehicle. The retinal structure was evaluated using fundus imaging and optical coherence tomography, and retinal function was assessed using a focal electroretinogram (ERG), two days after cytokine injection. Retinas were collected for biochemical analysis to determine key metabolite levels and enzymatic activities. Results Hyperglycemic mice intraocularly injected with cytokines developed visible retinal vascular damage and intravitreal and intraretinal hyper-reflective spots two days after the cytokines injection. These mice also developed a significant functional deficit with reduced a-wave and b-wave amplitudes of the ERG at high light intensities compared to control mice. Furthermore, metabolic disruption was evident in these mice, with significantly higher retinal glucose, lactate, ATP, and glutamine levels and a significant reduction in glutamate levels compared with control mice. Minimal or no metabolic changes were observed in hyperglycemic mice without intraocular cytokines or in control mice with intraocular cytokines at 2 days post hyperglycemia. Conclusions Proinflammatory cytokines accelerated the development of vascular damage in the eyes of hyperglycemic mice. Significant changes were observed in retinal structure, function, and metabolic homeostasis. These findings support the idea that with the onset of inflammation in DR, there is a deficit in metabolism. Therefore, early intervention to prevent inflammation-induced retinal changes in diabetic patients may improve the disease outcome.
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Characterization of NLRP3 Inflammasome Activation in the Onset of Diabetic Retinopathy. Int J Mol Sci 2022; 23:ijms232214471. [PMID: 36430950 PMCID: PMC9697159 DOI: 10.3390/ijms232214471] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 11/23/2022] Open
Abstract
The aim of this study was to characterize the role of nucleotide-binding oligomerization domain- (NOD-) like receptor (NLR) protein 3 (NLRP3) inflammasome activation in the onset of diabetic retinopathy (DR) using retina and vitreous from donors without diabetes mellitus (CTL), with diabetes mellitus alone (DM), and with DR. Retinal expression of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (Iba-1), the key markers of retinal inflammation, connexin43 (Cx43) which is involved in upstream inflammasome regulation, as well as NLRP3 and cleaved caspase-1, the main markers of inflammasome activation, were evaluated using immunohistochemistry and Western blotting. Vitreous interleukin (IL)-1β and IL-18, biomarkers of the activated inflammasome, were measured using a Luminex multiplex assay. Results showed a significant increase in the number and size of Iba-1+ cells and NLRP3 expression in DM, while a significant increase in GFAP, Cx43, cleaved caspase-1 and vitreous IL-18, as well as a further increase in Iba-1 and NLRP3 was found in DR. This suggests that the inflammasome is already primed in DM before its activation in DR. Furthermore, IL-18 may act as the major effector of inflammasome activation in DR while nuclear translocation of cleaved caspase-1 may play a role in gene transcription contributing to DR onset.
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Lai W, Huang J, Fang W, Deng S, Xie Y, Wang W, Qiao T, Xu G, Wang X, Ding F. Optic nerve head: A gatekeeper for vitreous infectious insults? Front Immunol 2022; 13:987771. [PMID: 36203577 PMCID: PMC9531234 DOI: 10.3389/fimmu.2022.987771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 08/31/2022] [Indexed: 11/19/2022] Open
Abstract
The axons of retinal ganglion cells (RGCs) pass through the optic nerve head (ONH) and form the optic nerve (ON). The ONH serves as an anatomical interface between the vitreous cavity and subarachnoid space. After inducing acute neuroinflammation by intravitreal injection of lipopolysaccharides (LPS), we observed inflammatory activation in the retina, but detect no signs of inflammation in the posterior ON or infiltration of inflammatory cells in the ONH. Therefore, we hypothesized that the ONH functions as a barrier to vitreous inflammation. Using transmission electron microscopy, we identified significant increase in G-ratio in the posterior ON on day 7 post intravitreal injection (PII) of LPS compared with the phosphate buffered saline (PBS) group. Moreover, using confocal imaging of ex vivo tissue extracted from Aldh1L1-eGFP reporter mice, we observed that the ONH astrocytes altered their spatial orientation by elongating their morphology along the axonal axis of RGCs in LPS- versus PBS-treated eyes; this was quantified by the ratio of longitudinal (DL) and transverse (DT) diameter of astrocytes and the proportion of longitudinally locating astrocytes. Supportive evidences were further provided by transmission electron microscopic imaging in rat ONH. We further conducted RNA sequencing of ONH on day 1 PII and found LPS induced clear upregulation of immune and inflammatory pathways. Furthermore, gene set enrichment analysis revealed that astrocyte and microglia contributed prominently to the transcriptomic alterations in ONH. Here, we report that the vitreous infectious insults induce morphological changes of ONH astrocytes and transcriptomic alterations in the ONH. Glial responses in the ONH may defend against vitreous infectious insults and serve as a barrier to inflammation for the central nervous system.
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Affiliation(s)
- Wenwen Lai
- Department of Pharmacology, School of Basic Medical Sciences; Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Fudan University, Shanghai, China
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jie Huang
- Department of Pharmacology, School of Basic Medical Sciences; Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Fudan University, Shanghai, China
- Department of Ophthalmology, Eye, Ear, Nose and Throat Hospital; State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Wangyi Fang
- Department of Ophthalmology, Shanghai Children’s Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Saiyue Deng
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yi Xie
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Wang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Tong Qiao
- Department of Ophthalmology, Shanghai Children’s Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Gezhi Xu
- Department of Pharmacology, School of Basic Medical Sciences; Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Fudan University, Shanghai, China
- Department of Ophthalmology, Eye, Ear, Nose and Throat Hospital; State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
| | - Xiaowei Wang
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA, United States
- *Correspondence: Fengfei Ding, ; Xiaowei Wang,
| | - Fengfei Ding
- Department of Pharmacology, School of Basic Medical Sciences; Shanghai Key Laboratory of Visual Impairment and Restoration, Science and Technology Commission of Shanghai Municipality, Fudan University, Shanghai, China
- Department of Ophthalmology, Eye, Ear, Nose and Throat Hospital; State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China
- *Correspondence: Fengfei Ding, ; Xiaowei Wang,
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Guo Y, Liu S, Xu H. Uric Acid and Diabetic Retinopathy: A Systematic Review and Meta-Analysis. Front Public Health 2022; 10:906760. [PMID: 35712295 PMCID: PMC9197488 DOI: 10.3389/fpubh.2022.906760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/09/2022] [Indexed: 11/13/2022] Open
Abstract
Background The relationship between uric acid (UA) and diabetic retinopathy (DR) remains ambiguous, and the results of current studies on the UA levels in patients with DR are conflicting. A meta-analysis was performed to provide a better understanding of the relationship between UA levels and DR. Methods PubMed, Web of Science, Embase, and the Cochrane Library databases were searched until December 11, 2021 to identify eligible studies, that compared the UA levels of the case group (patients with DR) and control group (controls with diabetes and healthy participants). The weighted mean difference (WMD) with a 95% confidence interval (CI) was used to evaluate the difference in UA levels between the case and control groups. Results Twenty-one studies involving 4,340 patients with DR and 8,595 controls (8,029 controls with diabetes and 566 healthy participants) were included in this meta-analysis. We found that patients with DR had significantly higher UA levels than those in the controls with diabetes (WMD = 36.28; 95% CI: 15.68, 56.89; P < 0.001) and healthy participants (WMD = 70.80; 95% CI: 19.85, 121.75; P = 0.006). There was an obvious heterogeneity among the 21 studies (I2 = 97%, P < 0.001). Subgroup analyses of different phases of DR showed that UA levels were significantly increased in participants with proliferative diabetic retinopathy (PDR) (WMD = 46.57; 95% CI: 28.51, 64.63; P < 0.001) than in controls with diabetes; however, the difference is not statistically significant when comparing UA levels in patients with non-proliferative diabetic retinopathy (NPDR) and controls with diabetes (WMD = 22.50; 95% CI: −6.07, 51.08; P = 0.120). In addition, UA levels were higher in participants with a body mass index (BMI) ≥25.0 kg/m2 and over 15 years of diabetes. Univariate meta-regression analysis revealed that BMI (P = 0.007, Adj R2 = 40.12%) and fasting blood glucose (FBG) (P = 0.040, Adj R2 = 29.72%) contributed to between-study heterogeneity. Conclusions In conclusion, our study provides evidence that UA levels are higher in patients with DR than those in the controls, but this difference is not statistically significant in the early phases. UA might be a potential biomarker for identifying disease severity in patients with DR, rather than predicting the onset of DR among patients with diabetes. However, more prospective and high-quality clinical evidence is required to confirm these present findings. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=297708.
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Affiliation(s)
- Yicong Guo
- Department of Social Medicine and Health Management, Xiangya School of Public Health, Central South University, Changsha, China
| | - Siyue Liu
- Department of Social Medicine and Health Management, Xiangya School of Public Health, Central South University, Changsha, China
| | - Huilan Xu
- Department of Social Medicine and Health Management, Xiangya School of Public Health, Central South University, Changsha, China
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11
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Liu L, Zuo Z. Excessive dietary salt promotes neuroinflammation to worsen retinopathy in mice with streptozotocin-induced diabetes. Biochim Biophys Acta Mol Basis Dis 2022; 1868:166426. [PMID: 35533904 DOI: 10.1016/j.bbadis.2022.166426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Diabetic retinopathy (DR) includes vascular and neural tissue injury. Persistent low-grade inflammation may contribute to DR. Increased salt intake has been shown to promote autoimmunity in the brain. This study determined the role of salt intake in DR development. METHODS Eight-week-old C57BL/6 J male mice received streptozotocin to induce diabetes. Diabetic or non-diabetic mice were fed a diet containing normal, low and high amounts of salt. The retinal function, structure and inflammatory response were determined 8 weeks after the establishment of diabetes. Interleukin (IL)-1β or a NLR family pyrin domain containing 3 (NLRP3) inhibitor was injected intravitreally and the retinal changes were evaluated. RESULTS A high salt diet worsened the functional and structural damage of retinal cells and increased IL-1β in the retina of diabetic mice. IL-1β injection impaired the function of photoreceptors and retinal structure in the diabetic mice. Blocking NLRP3 inhibited IL-1β increase in the mouse bone marrow macrophages cultured in high sodium medium. NLRP3 inhibition attenuated retinal injury of diabetic mice on high salt diet. A low-salt diet also triggered inflammation and cell damage in the retina of diabetic mice but at a lower grade than those induced by high salt diet. A low or high salt diet for 8 weeks did not induce inflammation or cell injury in the retina of mice without diabetes. CONCLUSION These results indicate that high salt intake has deleterious effects in DR development through NLRP3 inflammasome activation and the subsequent production of IL-1β. Limiting salt intake may not attenuate DR development.
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Affiliation(s)
- Lei Liu
- Department of Anesthesiology, University of Virginia, Charlottesville, VA, United States of America; Department of Ophthalmology, The First Hospital of Jilin University, Changchun 130021, China.
| | - Zhiyi Zuo
- Department of Anesthesiology, University of Virginia, Charlottesville, VA, United States of America.
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12
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Cliff CL, Williams BM, Chadjichristos CE, Mouritzen U, Squires PE, Hills CE. Connexin 43: A Target for the Treatment of Inflammation in Secondary Complications of the Kidney and Eye in Diabetes. Int J Mol Sci 2022; 23:600. [PMID: 35054783 PMCID: PMC8776095 DOI: 10.3390/ijms23020600] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 02/06/2023] Open
Abstract
Of increasing prevalence, diabetes is characterised by elevated blood glucose and chronic inflammation that precedes the onset of multiple secondary complications, including those of the kidney and the eye. As the leading cause of end stage renal disease and blindness in the working population, more than ever is there a demand to develop clinical interventions which can both delay and prevent disease progression. Connexins are membrane bound proteins that can form pores (hemichannels) in the cell membrane. Gated by cellular stress and injury, they open under pathophysiological conditions and in doing so release 'danger signals' including adenosine triphosphate into the extracellular environment. Linked to sterile inflammation via activation of the nod-like receptor protein 3 inflammasome, targeting aberrant hemichannel activity and the release of these danger signals has met with favourable outcomes in multiple models of disease, including secondary complications of diabetes. In this review, we provide a comprehensive update on those studies which document a role for aberrant connexin hemichannel activity in the pathogenesis of both diabetic eye and kidney disease, ahead of evaluating the efficacy of blocking connexin-43 specific hemichannels in these target tissues on tissue health and function.
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Affiliation(s)
- Chelsy L. Cliff
- Joseph Banks Laboratories, School of Life, Sciences University of Lincoln, Lincoln LN6 7DL, UK; (C.L.C.); (B.M.W.); (P.E.S.)
| | - Bethany M. Williams
- Joseph Banks Laboratories, School of Life, Sciences University of Lincoln, Lincoln LN6 7DL, UK; (C.L.C.); (B.M.W.); (P.E.S.)
| | - Christos E. Chadjichristos
- National Institutes for Health and Medical Research, UMR-S1155, Batiment Recherche, Tenon Hospital, 4 Rue de la Chine, 75020 Paris, France;
| | - Ulrik Mouritzen
- Ciana Therapeutics, Ole Maaloes Vej 3, 2200 Copenhagen N, Denmark;
| | - Paul E. Squires
- Joseph Banks Laboratories, School of Life, Sciences University of Lincoln, Lincoln LN6 7DL, UK; (C.L.C.); (B.M.W.); (P.E.S.)
| | - Claire E. Hills
- Joseph Banks Laboratories, School of Life, Sciences University of Lincoln, Lincoln LN6 7DL, UK; (C.L.C.); (B.M.W.); (P.E.S.)
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13
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Significance of Hyperreflective Foci as an Optical Coherence Tomography Biomarker in Retinal Diseases: Characterization and Clinical Implications. J Ophthalmol 2021; 2021:6096017. [PMID: 34956669 PMCID: PMC8709761 DOI: 10.1155/2021/6096017] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 11/30/2021] [Indexed: 02/03/2023] Open
Abstract
Hyperreflective foci (HRF) is a term coined to depict hyperreflective dots or roundish lesions within retinal layers visualized through optical coherence tomography (OCT). Histopathological correlates of HRF are not univocal, spacing from migrating retinal pigment epithelium cells, lipid-laden macrophages, microglial cells, and extravasated proteinaceous or lipid material. Despite this, HRF can be considered OCT biomarkers for disease progression, treatment response, and prognosis in several retinal diseases, including diabetic macular edema, age-related macular degeneration (AMD), retinal vascular occlusions, and inherited retinal dystrophies. The structural features and topographic location of HRF guide the interpretation of their significance in different pathological conditions. The presence of HRF less than 30 μm with reflectivity comparable to the retinal nerve fiber layer in the absence of posterior shadowing in diabetic macular edema indicates an inflammatory phenotype with a better response to steroidal treatment. In AMD, HRF overlying drusen are associated with the development of macular neovascularization, while parafoveal drusen and HRF predispose to macular atrophy. Thus, HRF can be considered a key biomarker in several common retinal diseases. Their recognition and critical interpretation via multimodal imaging are vital to support clinical strategies and management.
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14
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Shivashankar G, Lim JC, Acosta ML. Glyceraldehyde-3-phosphate dehydrogenase and glutamine synthetase inhibition in the presence of pro-inflammatory cytokines contribute to the metabolic imbalance of diabetic retinopathy. Exp Eye Res 2021; 213:108845. [PMID: 34800480 DOI: 10.1016/j.exer.2021.108845] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/12/2021] [Accepted: 11/12/2021] [Indexed: 12/18/2022]
Abstract
Diabetic retinopathy (DR) is the leading cause of vision impairment in working age adults. In addition to hyperglycemia, retinal inflammation is an important driving factor for DR development. Although DR is clinically described as diabetes-induced damage to the retinal blood vessels, several studies have reported that metabolic dysregulation occurs in the retina prior to the development of microvascular damage. The two most commonly affected metabolic pathways in diabetic conditions are glycolysis and the glutamate pathway. We investigated the role of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and glutamine synthetase (GS) in an in-vitro model of DR incorporating high glucose and pro-inflammatory cytokines. We found that GAPDH and GS enzyme activity were not significantly affected in hyperglycemic conditions or after exposure to cytokines alone, but were significantly decreased in the DR model. This confirmed that pro-inflammatory cytokines IL-1β and TNFα enhance the hyperglycemic metabolic deficit. We further investigated metabolite and amino acid levels after specific pharmacological inhibition of GAPDH or GS in the absence/presence of pro-inflammatory cytokines. The results indicate that GAPDH inhibition increased glucose and addition of cytokines increased lactate and ATP levels and reduced glutamate levels. GS inhibition did not alter retinal metabolite levels but the addition of cytokines increased ATP levels and caused glutamate accumulation in Müller cells. We conclude that it is the action of pro-inflammatory cytokines concomitantly with the inhibition of the glycolytic or GS mediated glutamate recycling that contribute to metabolic dysregulation in DR. Therefore, in the absence of good glycemic control, therapeutic interventions aimed at regulating inflammation may prevent the onset of early metabolic imbalance in DR.
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Affiliation(s)
- Gaganashree Shivashankar
- School of Optometry and Vision Science and the New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Julie C Lim
- Department of Physiology, School of Medical and Health Sciences and the New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science and the New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
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15
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Lyon H, Yin N, Rupenthal ID, Green CR, Mugisho OO. Blocking connexin43 hemichannels prevents TGF-β2 upregulation and epithelial-mesenchymal transition in retinal pigment epithelial cells. Cell Biol Int 2021; 46:323-330. [PMID: 34719065 DOI: 10.1002/cbin.11718] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/10/2021] [Accepted: 10/23/2021] [Indexed: 12/14/2022]
Abstract
Epithelial-mesenchymal transition (EMT) occurs when polarised epithelial cells change to a mesenchymal phenotype. EMT plays a role in several chronic conditions, including ocular diseases with retinal pigment epithelium (RPE) EMT associated with retinal diseases such as diabetic retinopathy (DR). Here, EMT results in breakdown of the blood-retinal barrier (BRB) leading to sub-retinal fluid deposition and retinal detachment. Previous studies have shown that blocking connexin43 (Cx43) hemichannels can protect against RPE BRB breakdown, but the underlying mechanism is unknown. To determine whether open Cx43 hemichannels may enable EMT of RPE cells and thus result in BRB breakdown, ARPE-19 cells were either challenged with high glucose plus the inflammatory cytokines IL-1β and TNF-α (HG + Cyt) to simulate DR or treated with the Cx43 hemichannel blocker tonabersat alongside the HG + Cyt challenge. HG + Cyt induced a morphological change in RPE cells to a fibroblastic phenotype with a corresponding decrease in epithelial zonular occludens-1 and an increase in the fibroblastic marker α-SMA. The HG + Cyt challenge also induced loss of transepithelial electrical resistance while increasing dye passage between RPE cells. All of these changes were significantly reduced with tonabersat treatment, which also prevented HG + Cyt-induced transforming growth factor-β2 (TGF-β2) release. In conclusion, Cx43 hemichannel block with tonabersat attenuated both TGF-β2 release and RPE EMT under disease-mimicking conditions, offering the potential to ameliorate the progression of EMT-associated retinal diseases.
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Affiliation(s)
- Heather Lyon
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Naibo Yin
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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16
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Quiroz J, Yazdanyar A. Animal models of diabetic retinopathy. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1272. [PMID: 34532409 PMCID: PMC8421981 DOI: 10.21037/atm-20-6737] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 12/23/2020] [Indexed: 12/16/2022]
Abstract
The retina is the posterior neuro-integrated layer of the eye that conducts impulses induced by light to the optic nerve for human vision. Diseases of the retina often leads to diminished vision and in some cases blindness. Diabetes mellitus (DM) is a worldwide public health issue and globally, there is an estimated 463 million people that are affected by DM and its consequences. Diabetic retinopathy (DR) is a blinding complication of chronic uncontrolled DM and is the most common cause of blindness in the United States between the ages 24-75. It is estimated that the global prevalence of DR will increase to 191.0 million by 2030, of those 56.3 million possessing vision-threatening diabetic retinopathy (VTDR). For the most part, current treatment modalities control the complications of DR without addressing the underlying pathophysiology of the disease. Therefore, there is an unmet need for new therapeutics that not only repair the damaged retinal tissue, but also reverse the course of DR. The key element in developing these treatments is expanding our basic knowledge by studying DR pathogenesis in animal models of proliferative and non-proliferative DR (PDR and NPDR). There are numerous models available for the research of both PDR and NPDR with substantial overlap. Animal models available include those with genetic backgrounds prone to hyperglycemic states, immunologic etiologies, or environmentally induced disease. In this review we aimed to comprehensively summarize the available animal models for DR while also providing insight to each model's ocular therapeutic potential for drug discovery.
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Affiliation(s)
- Jose Quiroz
- Medical Scientist Training Program, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Amirfarbod Yazdanyar
- Department of Ophthalmology and Visual Sciences, State University of New York (SUNY), Upstate Medical University, Syracuse, NY, USA
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17
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Shome A, Mugisho OO, Niederer RL, Rupenthal ID. Blocking the inflammasome: A novel approach to treat uveitis. Drug Discov Today 2021; 26:2839-2857. [PMID: 34229084 DOI: 10.1016/j.drudis.2021.06.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 05/24/2021] [Accepted: 06/30/2021] [Indexed: 12/11/2022]
Abstract
Uveitis is a complex ocular inflammatory disease often accompanied by bacterial or viral infections (infectious uveitis) or underlying autoimmune diseases (non-infectious uveitis). Treatment of the underlying infection along with corticosteroid-mediated suppression of acute inflammation usually resolves infectious uveitis. However, to develop more effective therapies for non-infectious uveitis and to better address acute inflammation in infectious disease, an improved understanding of the underlying inflammatory pathways is needed. In this review, we discuss the disease aetiology, preclinical in vitro and in vivo uveitis models, the role of inflammatory pathways, as well as current and future therapies. In particular, we highlight the involvement of the inflammasome in the development of non-infectious uveitis and how it could be a future target for effective treatment of the disease.
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Affiliation(s)
- Avik Shome
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Rachael L Niederer
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; Auckland District Health Board, Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
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18
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Choi JSY, de Haan JB, Sharma A. Animal models of diabetes-associated vascular diseases: an update on available models and experimental analysis. Br J Pharmacol 2021; 179:748-769. [PMID: 34131901 DOI: 10.1111/bph.15591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 03/08/2021] [Accepted: 06/01/2021] [Indexed: 12/19/2022] Open
Abstract
Diabetes is a chronic metabolic disorder associated with the accelerated development of macrovascular (atherosclerosis and coronary artery disease) and microvascular complications (nephropathy, retinopathy and neuropathy), which remain the principal cause of mortality and morbidity in this population. Current understanding of cellular and molecular pathways of diabetes-driven vascular complications, as well as therapeutic interventions has arisen from studying disease pathogenesis in animal models. Diabetes-associated vascular complications are multi-faceted, involving the interaction between various cellular and molecular pathways. Thus, the choice of an appropriate animal model to study vascular pathogenesis is important in our quest to identify innovative and mechanism-based targeted therapies to reduce the burden of diabetic complications. Herein, we provide up-to-date information on available mouse models of both Type 1 and Type 2 diabetic vascular complications as well as experimental analysis and research outputs.
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Affiliation(s)
- Judy S Y Choi
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Judy B de Haan
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, Victoria, Australia.,Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Victoria, Australia.,Faculty of Science, Engineering and Technology, Swinburne University, Melbourne, Victoria, Australia.,Baker Department of Cardiometabolic Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Arpeeta Sharma
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia.,Department of Diabetes, Monash University, Central Clinical School, Melbourne, Victoria, Australia
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19
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Nian S, Lo ACY, Mi Y, Ren K, Yang D. Neurovascular unit in diabetic retinopathy: pathophysiological roles and potential therapeutical targets. EYE AND VISION 2021; 8:15. [PMID: 33931128 PMCID: PMC8088070 DOI: 10.1186/s40662-021-00239-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 04/02/2021] [Indexed: 02/06/2023]
Abstract
Diabetic retinopathy (DR), one of the common complications of diabetes, is the leading cause of visual loss in working-age individuals in many industrialized countries. It has been traditionally regarded as a purely microvascular disease in the retina. However, an increasing number of studies have shown that DR is a complex neurovascular disorder that affects not only vascular structure but also neural tissue of the retina. Deterioration of neural retina could precede microvascular abnormalities in the DR, leading to microvascular changes. Furthermore, disruption of interactions among neurons, vascular cells, glia and local immune cells, which collectively form the neurovascular unit, is considered to be associated with the progression of DR early on in the disease. Therefore, it makes sense to develop new therapeutic strategies to prevent or reverse retinal neurodegeneration, neuroinflammation and impaired cell-cell interactions of the neurovascular unit in early stage DR. Here, we present current perspectives on the pathophysiology of DR as a neurovascular disease, especially at the early stage. Potential novel treatments for preventing or reversing neurovascular injuries in DR are discussed as well.
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Affiliation(s)
- Shen Nian
- Department of Pathology, Xi'an Medical University, Xi'an, Shaanxi Province, China.
| | - Amy C Y Lo
- Department of Ophthalmology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong
| | - Yajing Mi
- Institute of Basic Medicine Science, Xi'an Medical University, Xi'an, Shaanxi Province, China
| | - Kai Ren
- Department of Biochemistry and Molecular Biology, Xi'an Medical University, Xi'an, Shaanxi Province, China
| | - Di Yang
- Department of Ophthalmology, First Affiliated Hospital of Kunming Medical University, Kunming Medical University, Kunming, Yunnan Province, China.
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20
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Mrugacz M, Bryl A, Zorena K. Retinal Vascular Endothelial Cell Dysfunction and Neuroretinal Degeneration in Diabetic Patients. J Clin Med 2021; 10:jcm10030458. [PMID: 33504108 PMCID: PMC7866162 DOI: 10.3390/jcm10030458] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/11/2021] [Accepted: 01/19/2021] [Indexed: 12/13/2022] Open
Abstract
Diabetes mellitus (DM) has become a vital societal problem as epidemiological studies demonstrate the increasing incidence of type 1 and type 2 diabetes. Lesions observed in the retina in the course of diabetes, referred to as diabetic retinopathy (DR), are caused by vascular abnormalities and are ischemic in nature. Vascular lesions in diabetes pertain to small vessels (microangiopathy) and involve precapillary arterioles, capillaries and small veins. Pericyte loss, thickening of the basement membrane, and damage and proliferation of endothelial cells are observed. Endothelial cells (monolayer squamous epithelium) form the smooth internal vascular lining indispensable for normal blood flow. Breaking its continuity initiates blood coagulation at that site. The endothelium controls the process of exchange of chemical substances (nutritional, regulatory, waste products) between blood and the retina, and blood cell passing through the vascular wall. Endothelial cells produce biologically active substances involved in blood coagulation, regulating vascular wall tension and stimulating neoangiogenesis. On the other hand, recent studies have demonstrated that diabetic retinopathy may be not only a microvascular disease, but is a result of neuroretinal degeneration. Neuroretinal degeneration appears structurally, as neural apoptosis of amacrine and Muller cells, reactive gliosis, ganglion cell layer/inner plexiform (GCL) thickness, retinal thickness, and retinal nerve fiber layer thickness, and a reduction of the neuroretinal rim in minimum rim width (MRW) and functionally as an abnormal electroretinogram (ERG), dark adaptation, contrast sensitivity, color vision, and microperimetric test. The findings in early stages of diabetic retinopathy may precede microvascular changes of this disease. Furthermore, the article's objective is to characterize the factors and mechanisms conducive to microvascular changes and neuroretinal apoptosis in diabetic retinopathy. Only when all the measures preventing vascular dysfunction are determined will the risk of complications in the course of diabetes be minimized.
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Affiliation(s)
- Malgorzata Mrugacz
- Department of Ophthalmology and Eye Rehabilitation, Medical University of Bialystok, 15-089 Białystok, Poland
| | - Anna Bryl
- Department of Ophthalmology and Eye Rehabilitation, Medical University of Bialystok, 15-089 Białystok, Poland
| | - Katarzyna Zorena
- Department of Immunobiology and Environment Microbiology, Medical University of Gdańsk, 18-211 Gdańsk, Poland
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21
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Lin Y, Ren X, Chen Y, Chen D. Interaction Between Mesenchymal Stem Cells and Retinal Degenerative Microenvironment. Front Neurosci 2021; 14:617377. [PMID: 33551729 PMCID: PMC7859517 DOI: 10.3389/fnins.2020.617377] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/17/2020] [Indexed: 02/06/2023] Open
Abstract
Retinal degenerative diseases (RDDs) are a group of diseases contributing to irreversible vision loss with yet limited therapies. Stem cell-based therapy is a promising novel therapeutic approach in RDD treatment. Mesenchymal stromal/stem cells (MSCs) have emerged as a leading cell source due to their neurotrophic and immunomodulatory capabilities, limited ethical concerns, and low risk of tumor formation. Several pre-clinical studies have shown that MSCs have the potential to delay retinal degeneration, and recent clinical trials have demonstrated promising safety profiles for the application of MSCs in retinal disease. However, some of the clinical-stage MSC therapies have been unable to meet primary efficacy end points, and severe side effects were reported in some retinal “stem cell” clinics. In this review, we provide an update of the interaction between MSCs and the RDD microenvironment and discuss how to balance the therapeutic potential and safety concerns of MSCs' ocular application.
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Affiliation(s)
- Yu Lin
- The Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China.,The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Xiang Ren
- The Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China.,The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Yongjiang Chen
- The School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - Danian Chen
- The Research Laboratory of Ophthalmology and Vision Sciences, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China.,The Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
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22
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Kang H, Yin N, Lyon H, Rupenthal ID, Thakur SS, Mugisho OO. The influence of hyperglycemia on the safety of ultrasound in retinal pigment epithelial cells. Cell Biol Int 2021; 45:558-568. [PMID: 33049086 DOI: 10.1002/cbin.11477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/13/2020] [Accepted: 10/10/2020] [Indexed: 11/07/2022]
Abstract
Ultrasound (US) assisted drug delivery is receiving interest in treating posterior eye diseases, such as diabetic retinopathy due to its ability to maximize drug penetration into difficult to reach tissues. Despite its promise, the technique has only been investigated using healthy cell and tissue models, with no evidence to date about its safety in active disease. As a result, the aim of this study was to evaluate the safety of US administration in vitro in retinal pigment epithelial cells under normal and high glucose conditions. US protocols within the presently accepted safety threshold were applied and their influence on cell membrane and tight junction integrity as well as intracellular inflammation was evaluated using lactate dehydrogenase (LDH), zona occludens-1 (ZO-1), fluorescein isothiocyanate (FITC)-dextran dye leak and nuclear factor-kappaB (NF-κB) assays, respectively. Under high glucose conditions, US application increased LDH release and resulted in loss of ZO-1 labeling at 2 h; however, normal levels were restored within 24 h. US within its safety parameters did not induce any FITC-dextran dye leak or NF-κB nuclear translocation in normal or high glucose conditions. In conclusion, our results suggest that while high glucose conditions increase cell susceptibility to US-mediated stress, basal conditions can be restored within 24 h without long-lasting cell damage.
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Affiliation(s)
- Heather Kang
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Center, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Naibo Yin
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Center, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.,School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Heather Lyon
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Center, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Center, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Sachin S Thakur
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Center, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.,School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Center, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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23
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Louie HH, Shome A, Kuo CY, Rupenthal ID, Green CR, Mugisho OO. Connexin43 hemichannel block inhibits NLRP3 inflammasome activation in a human retinal explant model of diabetic retinopathy. Exp Eye Res 2020; 202:108384. [PMID: 33285185 DOI: 10.1016/j.exer.2020.108384] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 11/24/2020] [Accepted: 11/30/2020] [Indexed: 01/26/2023]
Abstract
Diabetic retinopathy (DR), the most common ocular complication associated with diabetes, is a chronic vascular and inflammatory disease that leads to vision loss. The inflammasome pathway, a key part of the innate immune system, is required to activate chronic inflammation in DR. Unfortunately, current therapies for DR target pathological signs that are downstream of the inflammasome pathway, making them only partly effective in treating the disease. Using in vitro and in vivo DR models, it was discovered that connexin43 hemichannel blockers can inhibit activation of the inflammasome pathway. However, those studies were conducted using in vitro cell culture and in vivo animal disease models that are predictive but do not, of course, like any model, completely replicate the human condition. Here, we have developed an addition to our armamentarium of useful models, an ex vivo human organotypic retinal culture model of DR by exposing human donor retinal explants to a combination of high glucose (HG) and pro-inflammatory cytokines, interleukin-1 beta (IL-1β) and tumour necrosis factor alpha (TNF-α). We hypothesized that in this model, connexin43 hemichannel block would protect against NLRP3 inflammasome complex assembly which would in turn decrease signs of inflammation characteristic of DR. To test our hypothesis, molecular changes in the inflammatory and inflammasome pathway were assessed using immunohistochemistry and a Luminex cytokine release assay. Our results showed that the human retinal explant DR model was associated with increased inflammation and activation of the inflammasome pathway, characteristic of the human condition. Furthermore, we showed that by blocking connexin43 hemichannels with the hemichannel modulator, tonabersat, we were able to prevent NLRP3 inflammasome complex assembly, Müller cell activation, as well as release of pro-inflammatory cytokines and VEGF. This further supports the possible use of connexin43 hemichannel blockers as potential new therapies for DR.
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Affiliation(s)
- Henry H Louie
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Avik Shome
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Charisse Yj Kuo
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand.
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24
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The Immunomodulatory Potential of Mesenchymal Stem Cells in a Retinal Inflammatory Environment. Stem Cell Rev Rep 2020; 15:880-891. [PMID: 31863334 DOI: 10.1007/s12015-019-09908-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Retinal degenerative disorders are characterized by a local upregulation of inflammatory factors, infiltration with cells of the immune system, a vascular dysfunction and by the damage of retinal cells. There is still a lack of treatment protocols for these diseases. Mesenchymal stem cell (MSC)-based therapy using immunoregulatory, regenerative and differentiating properties of MSCs offers a promising treatment option. In this study, we analyzed the immunomodulatory properties of mouse bone marrow-derived MSCs after their intravitreal delivery to the inflammatory environment in the eye, caused by the application of pro-inflammatory cytokines IL-1β, TNF-α and IFN-γ. The intravitreal administration of these cytokines induces an increased expression of pro-inflammatory molecules such as IL-1α, IL-6, inducible nitric oxide synthase, TNF-α and vascular endothelial growth factor in the retina. However, a significant decrease in the expression of genes for all these pro-inflammatory molecules was observed after the intravitreal injection of MSCs. We further showed that an increased infiltration of the retina with immune cells, mainly with macrophages, which was observed after pro-inflammatory cytokine application, was significantly reduced after the intravitreal application of MSCs. The similar immunosuppressive effects of MSCs were also demonstrated in vitro in cultures of cytokine-stimulated retinal explants and MSCs. Overall, the results show that intravitreal application of MSCs inhibits the early retinal inflammation caused by pro-inflammatory cytokines, and propose MSCs as a promising candidate for stem cell-based therapy of retinal degenerative diseases.
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25
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Avrutsky MI, Ortiz CC, Johnson KV, Potenski AM, Chen CW, Lawson JM, White AJ, Yuen SK, Morales FN, Canepa E, Snipas S, Salvesen GS, Jean YY, Troy CM. Endothelial activation of caspase-9 promotes neurovascular injury in retinal vein occlusion. Nat Commun 2020; 11:3173. [PMID: 32576823 PMCID: PMC7311551 DOI: 10.1038/s41467-020-16902-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 06/02/2020] [Indexed: 12/27/2022] Open
Abstract
Central nervous system ischemic injury features neuronal dysfunction, inflammation and breakdown of vascular integrity. Here we show that activation of endothelial caspase-9 after hypoxia-ischemia is a critical event in subsequent dysfunction of the blood-retina barrier, using a panel of interrelated ophthalmic in vivo imaging measures in a mouse model of retinal vein occlusion (RVO). Rapid nonapoptotic activation of caspase-9 and its downstream effector caspase-7 in endothelial cells promotes capillary ischemia and retinal neurodegeneration. Topical eye-drop delivery of a highly selective caspase-9 inhibitor provides morphological and functional retinal protection. Inducible endothelial-specific caspase-9 deletion phenocopies this protection, with attenuated retinal edema, reduced inflammation and preserved neuroretinal morphology and function following RVO. These results reveal a non-apoptotic function of endothelial caspase-9 which regulates blood-retina barrier integrity and neuronal survival, and identify caspase-9 as a therapeutic target in neurovascular disease. Retinal vein occlusion can cause blindness, and features neuronal dysfunction, inflammation and breakdown of vascular integrity. Here the authors report a non-apoptotic role of endothelial caspase-9 in regulating blood-retina barrier integrity and neuronal survival, which can be therapeutically targeted in a mouse model of retinal vein occlusion.
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Affiliation(s)
- Maria I Avrutsky
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Crystal Colón Ortiz
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Kendra V Johnson
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Anna M Potenski
- Department of Pharmacology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Claire W Chen
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Jacqueline M Lawson
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Alexandra J White
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Stephanie K Yuen
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Fatima N Morales
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Elisa Canepa
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Scott Snipas
- NCI-designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute La Jolla, La Jolla, CA, 92037, USA
| | - Guy S Salvesen
- NCI-designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute La Jolla, La Jolla, CA, 92037, USA
| | - Ying Y Jean
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Carol M Troy
- Department of Pathology & Cell Biology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA. .,Department of Neurology; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA. .,The Taub Institute for Research on Alzheimer's Disease and the Aging Brain; Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA.
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26
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Shivashankar G, Lim JC, Acosta ML. Proinflammatory cytokines trigger biochemical and neurochemical changes in mouse retinal explants exposed to hyperglycemic conditions. Mol Vis 2020; 26:277-290. [PMID: 32300272 PMCID: PMC7155896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 04/09/2020] [Indexed: 12/04/2022] Open
Abstract
PURPOSE Diabetic retinopathy (DR) is one of the most frequent complications of diabetes affecting the retina and eventually causing vision impairment. Emerging evidence suggests that inflammation plays a vital role in DR progression. In this study, we evaluated the early biochemical and neurochemical changes in mouse retinal explants to understand the contribution of proinflammatory cytokines to disease progression. METHODS DR was modeled in vitro by incubating mouse retinal explants in a physiological buffer supplemented with high glucose and the proinflammatory cytokines TNF-α and IL-1β. Key metabolites of retinal energy metabolism, including glucose, lactate, ATP, glutamate, glutamine, and enzymes supporting retinal ATP levels were assessed 40 min after the application of high glucose and proinflammatory cytokines. As retinal energy metabolism is tightly coupled to retinal neurochemistry, we also determined the short-term effect on the amino acid distribution of glutamate, gamma aminobutyric acid (GABA), glutamine, and glycine. RESULTS The results indicated that the combined application of high glucose and proinflammatory cytokines increased retinal glucose, lactate, and ATP levels, and decreased retinal glutamate, without affecting glutamine levels or the enzymes supporting ATP levels. Moreover, we observed a statistically significant increase in ATP and glutamate release. Correspondingly, statistically significant alterations in amino acid distribution were observed in retinal explants coexposed to high glucose and proinflammatory cytokines. CONCLUSIONS These data suggest that short-term exposure to proinflammatory cytokines contributes to the early biochemical and neurochemical changes caused by hyperglycemia, by affecting retinal energy metabolism and amino acid distribution. These data are consistent with the idea that early intervention to prevent inflammation-triggered loss of metabolic homeostasis in patients with diabetes is necessary to prevent DR progression.
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Affiliation(s)
- Gaganashree Shivashankar
- School of Optometry and Vision Science and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Julie C. Lim
- Department of Physiology, School of Medical and Health Sciences and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Monica L. Acosta
- School of Optometry and Vision Science and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
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27
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Kuo C, Green CR, Rupenthal ID, Mugisho OO. Connexin43 hemichannel block protects against retinal pigment epithelial cell barrier breakdown. Acta Diabetol 2020; 57:13-22. [PMID: 31030263 DOI: 10.1007/s00592-019-01352-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 04/16/2019] [Indexed: 01/05/2023]
Abstract
AIMS The retinal pigment epithelium (RPE) is an important component of the outer blood-retinal barrier (BRB) that separates the choroid from the rest of the retina. Loss of RPE-mediated BRB integrity is a key feature of diabetic macular oedema (DME), a chronic pathology resulting from diabetic retinopathy (DR). Recent studies have shown that connexin43 hemichannel opening mediates key inflammatory pathways in DR, though its effect on the barrier properties of RPE cells remains unknown. Therefore, RPE breakdown was induced by exposing a monolayer of ARPE-19 cells to high glucose (HG) and 10 ng/mL each of the pro-inflammatory cytokines IL-1β and TNF-α. The role of connexin43 hemichannels was assessed using a connexin43 hemichannel blocker, Peptide5. METHODS Transepithelial resistance (TEER) and FITC-dextran dye leak across the ARPE-19 monolayer were used to measure RPE layer permeability. Immunohistochemistry was used to assess changes in connexin43, collagen IV and ZO-1 expression. ATP and lactate dehydrogenase (LDH) release were measured using commercially available kits. RESULTS Connexin43 hemichannel block with Peptide5 prevented TEER reduction and FITC-dextran dye leak induced by a combination of HG and inflammatory cytokines. Peptide5 also blocked LDH and ATP release induced by the addition of HG and inflammatory cytokines. ZO-1 and connexin43 disruption and internalisation as well as upregulated secretion of collagen IV following HG and inflammatory cytokine exposure were also prevented. The addition of exogenous ATP into the culture medium was able to reverse Peptide5 protection against LDH release and change in connexin43 localisation, indicating that the initiating pathway in RPE disruption is connexin43 hemichannel-mediated ATP release. CONCLUSION These findings support the idea that connexin43 hemichannels may mediate RPE disruption (and its role within the BRB) that occurs in DME through an ATP release/inflammasome pathway activation dependent manner. Connexin43 hemichannels are therefore a potential therapeutic target for the treatment of DME.
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Affiliation(s)
- Charisse Kuo
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
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Mat Nor MN, Rupenthal ID, Green CR, Acosta ML. Connexin Hemichannel Block Using Orally Delivered Tonabersat Improves Outcomes in Animal Models of Retinal Disease. Neurotherapeutics 2020; 17:371-387. [PMID: 31637594 PMCID: PMC7007471 DOI: 10.1007/s13311-019-00786-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Increased Connexin43 hemichannel opening is associated with inflammasome pathway activation and inflammation in a range of pathologies including ocular disorders, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). In this study, the effect on retinal function and morphology of clinically safe doses of orally delivered tonabersat, a small molecule connexin hemichannel blocker, was investigated in the light-damaged retina animal model of dry AMD and in a spontaneous rat model of DR. Clinical parameters (fundus imaging, optical coherence tomography (OCT), and electroretinography) and inflammatory markers (immunohistochemistry for Iba-1 microglial marker, astrocyte marker glial fibrillary acidic protein, and Connexin43 protein expression) were assessed. Tonabersat treatment reduced inflammation in the retina in parallel with preservation of retinal photoreceptor function when assessed up to 3 months post light damage in the dry AMD model. In the DR model, clinical signs, including the presence of aneurysms confirmed using Evans blue dye perfusion, were reduced after daily tonabersat treatment for 2 weeks. Inflammation was also reduced and retinal electrical function restored. Tonabersat regulates assembly of the inflammasome (NLRP3) through Connexin43 hemichannel block, with the potential to reduce inflammation, restore vascular integrity and improve anatomical along with some functional outcomes in retinal disease.
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Affiliation(s)
- Mohd Nasir Mat Nor
- School of Optometry and Vision Science and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
- Faculty of Medicine, University of Sultan Zainal Abidin, Kuala Terengganu, Malaysia
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
- Department of Ophthalmology and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
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29
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Holan V, Hermankova B, Krulova M, Zajicova A. Cytokine interplay among the diseased retina, inflammatory cells and mesenchymal stem cells - a clue to stem cell-based therapy. World J Stem Cells 2019; 11:957-967. [PMID: 31768222 PMCID: PMC6851013 DOI: 10.4252/wjsc.v11.i11.957] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/02/2019] [Accepted: 09/14/2019] [Indexed: 02/06/2023] Open
Abstract
Retinal degenerative disorders, such as diabetic retinopathy, retinitis pigmentosa, age-related macular degeneration or glaucoma, represent the most common causes of loss of vision and blindness. In spite of intensive research, treatment options to prevent, stop or cure these diseases are limited. Newer therapeutic approaches are offered by stem cell-based therapy. To date, various types of stem cells have been evaluated in a range of models. Among them, mesenchymal stem/stromal cells (MSCs) derived from bone marrow or adipose tissue and used as autologous cells have been proposed to have the potential to attenuate the negative manifestations of retinal diseases. MSCs delivered to the vicinity of the diseased retina can exert local anti-inflammatory and repair-promoting/regenerative effects on retinal cells. However, MSCs also produce numerous factors that could have negative impacts on retinal regeneration. The secretory activity of MSCs is strongly influenced by the cytokine environment. Therefore, the interactions among the molecules produced by the diseased retina, cytokines secreted by inflammatory cells and factors produced by MSCs will decide the development and propagation of retinal diseases. Here we discuss the interactions among cytokines and other factors in the environment of the diseased retina treated by MSCs, and we present results supporting immunoregulatory and trophic roles of molecules secreted in the vicinity of the retina during MSC-based therapy.
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Affiliation(s)
- Vladimir Holan
- Department of Transplantation Immunology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague 14220, Czech Republic
- Department of Cell Biology, Faculty of Science, Charles University, Prague 12843, Czech Republic
| | - Barbora Hermankova
- Department of Transplantation Immunology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague 14220, Czech Republic
- Department of Cell Biology, Faculty of Science, Charles University, Prague 12843, Czech Republic
| | - Magdalena Krulova
- Department of Transplantation Immunology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague 14220, Czech Republic
- Department of Cell Biology, Faculty of Science, Charles University, Prague 12843, Czech Republic
| | - Alena Zajicova
- Department of Transplantation Immunology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague 14220, Czech Republic
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30
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Mugisho OO, Rupenthal ID, Paquet-Durand F, Acosta ML, Green CR. Targeting connexin hemichannels to control the inflammasome: the correlation between connexin43 and NLRP3 expression in chronic eye disease. Expert Opin Ther Targets 2019; 23:855-863. [PMID: 31554417 DOI: 10.1080/14728222.2019.1673368] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Introduction: Chronic inflammatory diseases, including retinal diseases that are a major cause of vision loss, are associated with activation of the nucleotide-binding domain and leucine-rich repeat containing (NLR) protein-3 (NLRP3) inflammasome pathway. In chronic disease, the inflammasome becomes self-perpetuating, indicating a common pathway in such diseases irrespective of underlying etiology, and implying a shared solution is feasible. Connexin43 hemichannels correlate directly with NLRP3 inflammasome complex assembly (shown here in models of retinal disease). Connexin43 hemichannel-mediated ATP release is proposed to be the principal activator signal for inflammasome complex assembly in primary signal-sensitized cells. Connexin hemichannel block on its own is sufficient to inhibit the inflammasome pathway. Areas covered: We introduce chronic retinal disease, discuss available preclinical models and examine findings from these models regarding the targeting of connexin43 hemichannels and its effects on the inflammasome. Expert opinion: In over 25 animal disease models, connexin hemichannel regulation has shown therapeutic benefit, and one oral connexin hemichannel blocker, tonabersat (Xiflam), is Phase II ready with safety evidence in over 1000 patients. Regulating the connexin hemichannel provides a means to move quickly into clinical trials designed to ameliorate the progression of devastating chronic diseases of the eye, but also elsewhere in the body.
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Affiliation(s)
- Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland , New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland , New Zealand
| | - Francois Paquet-Durand
- Cell Death Mechanisms Lab, Institute for Ophthalmic Research, University of Tübingen , Tübingen , Germany
| | - Monica L Acosta
- School of Optometry and Vision Science and the New Zealand National Eye Centre, University of Auckland , Auckland , New Zealand
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland , Auckland , New Zealand
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31
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Black JM, Jacobs RJ, Phillips JR, Acosta ML. The changing scope of Optometry in New Zealand: historical perspectives, current practice and research advances. J R Soc N Z 2019. [DOI: 10.1080/03036758.2019.1587476] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Joanna M. Black
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Robert J. Jacobs
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - John R. Phillips
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Monica L. Acosta
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
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32
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Rong X, Tian H, Yang L, Li W. Function-first ligandomics for ocular vascular research and drug target discovery. Exp Eye Res 2019; 182:57-64. [PMID: 30904565 DOI: 10.1016/j.exer.2019.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/21/2019] [Accepted: 03/15/2019] [Indexed: 12/29/2022]
Abstract
Human eyes may develop different vascular diseases with neovascularization and/or leakage, including wet age-related macular degeneration (AMD), diabetic macular edema (DME), proliferative diabetic retinopathy (PDR), retinopathy of prematurity, corneal neovascularization and intraocular tumors. A breakthrough in therapy is the advent and approval of vascular endothelial growth factor (VEGF) inhibitors. However, anti-VEGF drugs not only have limited efficacy to treat AMD, DME and PDR but also are not approved for other ocular indications. The key to addressing these unmet clinical needs is to develop novel therapies against VEGF-independent angiogenic factors or signaling pathways for alternative or combination therapy. We recently developed the first paradigm of ligandomics for global mapping of cell-wide ligands as well as disease-selective ligands. Therapies targeting disease-selective angiogenic or vascular leakage factors likely have high efficacy, minimal side effects, wide therapeutic windows and relatively low drug attrition rates. A critical challenge is how to distinguish between genuine drug targets and spurious hits identified by high-throughput ligandomics. Here we exploited the unique advantages of the eye and extracellular ligands by combining ligandomics with "function-first" and/or "therapy-first" analyses to efficiently characterize functional activity, disease selectivity, pathogenic role and therapeutic potential of identified ligands. The innovative function- or therapy-first ligandomics will systematically and reliably delineate disease-selective angiogenic or vascular leakage factors and markedly facilitate ocular vascular research and ligand-guided targeted anti-angiogenic therapy.
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Affiliation(s)
- Xin Rong
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | | | - Liu Yang
- Department of Ophthalmology, Peking University First Hospital, Beijing, China
| | - Wei Li
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, FL, USA.
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Mugisho OO, Green CR, Zhang J, Acosta ML, Rupenthal ID. Connexin43 hemichannels: A potential drug target for the treatment of diabetic retinopathy. Drug Discov Today 2019; 24:1627-1636. [PMID: 30690195 DOI: 10.1016/j.drudis.2019.01.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/17/2019] [Accepted: 01/17/2019] [Indexed: 02/07/2023]
Abstract
Diabetic retinopathy (DR) is a chronic vascular disease of the retina that causes vision loss in patients with type 1 and type 2 diabetes, and is associated with vascular dysfunction and occlusion, retinal oedema, haemorrhage and inadequate growth of new blood vessels. Current DR therapies primarily target downstream, later-stage vascular defects with a significant proportion of diabetic macular oedema patients being non-responders. Moreover, other evidence suggests that prolonged use of therapies targeting vascular endothelial growth factor (VEGF) might be associated with increased onset of geographic atrophy and retinal ganglion cell death. It is therefore highly desirable to prevent the onset of DR or arrest its progression at a stage preceding the appearance of more-advanced pathology by targeting upstream disease mechanisms. Connexin43 hemichannels play a part in the pathogenesis of chronic inflammatory diseases, including inflammasome pathway activation; and hemichannel block has been shown to alleviate vascular leak and inflammation. This review discusses the inflammatory changes occurring in DR as well as current therapies and their limitations. It then focuses on the role of connexin43 in DR, providing evidence for the utility of connexin43 hemichannel blockers as novel therapeutics for DR treatment.
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Affiliation(s)
- Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Jie Zhang
- Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand.
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34
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Gucciardo E, Loukovaara S, Salven P, Lehti K. Lymphatic Vascular Structures: A New Aspect in Proliferative Diabetic Retinopathy. Int J Mol Sci 2018; 19:ijms19124034. [PMID: 30551619 PMCID: PMC6321212 DOI: 10.3390/ijms19124034] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/07/2018] [Accepted: 12/11/2018] [Indexed: 12/28/2022] Open
Abstract
Diabetic retinopathy (DR) is the most common diabetic microvascular complication and major cause of blindness in working-age adults. According to the level of microvascular degeneration and ischemic damage, DR is classified into non-proliferative DR (NPDR), and end-stage, proliferative DR (PDR). Despite advances in the disease etiology and pathogenesis, molecular understanding of end-stage PDR, characterized by ischemia- and inflammation-associated neovascularization and fibrosis, remains incomplete due to the limited availability of ideal clinical samples and experimental research models. Since a great portion of patients do not benefit from current treatments, improved therapies are essential. DR is known to be a complex and multifactorial disease featuring the interplay of microvascular, neurodegenerative, metabolic, genetic/epigenetic, immunological, and inflammation-related factors. Particularly, deeper knowledge on the mechanisms and pathophysiology of most advanced PDR is critical. Lymphatic-like vessel formation coupled with abnormal endothelial differentiation and progenitor cell involvement in the neovascularization associated with PDR are novel recent findings which hold potential for improved DR treatment. Understanding the underlying mechanisms of PDR pathogenesis is therefore crucial. To this goal, multidisciplinary approaches and new ex vivo models have been developed for a more comprehensive molecular, cellular and tissue-level understanding of the disease. This is the first step to gain the needed information on how PDR can be better evaluated, stratified, and treated.
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Affiliation(s)
- Erika Gucciardo
- Research Programs Unit, Genome-Scale Biology, Biomedicum Helsinki, University of Helsinki, FI-00014 Helsinki, Finland.
| | - Sirpa Loukovaara
- Unit of Vitreoretinal Surgery, Ophthalmology, University of Helsinki and Helsinki University Hospital, FI-00014 Helsinki, Finland.
| | - Petri Salven
- Department of Pathology, University of Helsinki and Helsinki University Hospital, FI-00014 Helsinki, Finland.
| | - Kaisa Lehti
- Research Programs Unit, Genome-Scale Biology, Biomedicum Helsinki, University of Helsinki, FI-00014 Helsinki, Finland.
- Department of Microbiology, Tumor, and Cell Biology (MTC), Karolinska Institutet, SE-17165 Stockholm, Sweden.
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35
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Connexin43 hemichannel block protects against the development of diabetic retinopathy signs in a mouse model of the disease. J Mol Med (Berl) 2018; 97:215-229. [DOI: 10.1007/s00109-018-1727-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/25/2018] [Accepted: 11/30/2018] [Indexed: 12/22/2022]
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