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  1. Article ; Online: Cross Talks between Oxidative Stress, Inflammation and Epigenetics in Diabetic Retinopathy.

    Kowluru, Renu A

    Cells

    2023  Volume 12, Issue 2

    Abstract: Diabetic retinopathy, one of the most devastating complications of diabetes, is a multifactorial progressing disease with a very complex etiology. Although many metabolic, molecular, functional and structural changes have been identified in the retina ... ...

    Abstract Diabetic retinopathy, one of the most devastating complications of diabetes, is a multifactorial progressing disease with a very complex etiology. Although many metabolic, molecular, functional and structural changes have been identified in the retina and its vasculature, the exact molecular mechanism of its pathogenesis still remains elusive. Sustained high-circulating glucose increases oxidative stress in the retina and also activates the inflammatory cascade. Free radicals increase inflammatory mediators, and inflammation can increase production of free radicals, suggesting a positive loop between them. In addition, diabetes also facilitates many epigenetic modifications that can influence transcription of a gene without changing the DNA sequence. Several genes associated with oxidative stress and inflammation in the pathogenesis of diabetic retinopathy are also influenced by epigenetic modifications. This review discusses cross-talks between oxidative stress, inflammation and epigenetics in diabetic retinopathy. Since epigenetic changes are influenced by external factors such as environment and lifestyle, and they can also be reversed, this opens up possibilities for new strategies to inhibit the development/progression of this sight-threatening disease.
    MeSH term(s) Humans ; Diabetic Retinopathy/pathology ; Epigenesis, Genetic ; Inflammation/genetics ; Oxidative Stress ; Free Radicals/metabolism ; Diabetes Mellitus/genetics
    Chemical Substances Free Radicals
    Language English
    Publishing date 2023-01-12
    Publishing country Switzerland
    Document type Journal Article ; Review ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2661518-6
    ISSN 2073-4409 ; 2073-4409
    ISSN (online) 2073-4409
    ISSN 2073-4409
    DOI 10.3390/cells12020300
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Diabetic Retinopathy and Regulation of Mitochondrial Glutathione-Glutathione Peroxidase Axis in Hyperhomocysteinemia.

    Malaviya, Pooja / Kowluru, Renu A

    Antioxidants (Basel, Switzerland)

    2024  Volume 13, Issue 3

    Abstract: Diabetic patients have elevated homocysteine levels, and hyperhomocysteinemia is shown to exacerbate mitochondrial damage, which plays a central role in diabetic retinopathy. Glutathione peroxidases (GPx) catalyze hydrogen peroxide ( ... ...

    Abstract Diabetic patients have elevated homocysteine levels, and hyperhomocysteinemia is shown to exacerbate mitochondrial damage, which plays a central role in diabetic retinopathy. Glutathione peroxidases (GPx) catalyze hydrogen peroxide (H
    Language English
    Publishing date 2024-02-20
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2704216-9
    ISSN 2076-3921
    ISSN 2076-3921
    DOI 10.3390/antiox13030254
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Homocysteine and mitochondrial quality control in diabetic retinopathy.

    Malaviya, Pooja / Kowluru, Renu A

    Eye and vision (London, England)

    2024  Volume 11, Issue 1, Page(s) 5

    Abstract: Background: Diabetic retinopathy is a progressive disease, and one of the key metabolic abnormalities in the pathogenesis of diabetic retinopathy, mitochondrial damage, is also influenced by the duration of hyperglycemia. Mitochondrial quality control ... ...

    Abstract Background: Diabetic retinopathy is a progressive disease, and one of the key metabolic abnormalities in the pathogenesis of diabetic retinopathy, mitochondrial damage, is also influenced by the duration of hyperglycemia. Mitochondrial quality control involves a coordination of mitochondrial dynamics, biogenesis and removal of the damaged mitochondria. In diabetes, these processes are impaired, and the damaged mitochondria continue to produce free radicals. Diabetic patients also have high homocysteine and reduced levels of hydrogen sulfide, and hyperhomocysteinemia is shown to exacerbate diabetes-induced mitochondrial damage and worsen their dynamics. This study aims to investigate the temporal relationship between hyperhomocysteinemia and retinal mitochondrial quality control in diabetic retinopathy.
    Methods: Human retinal endothelial cells incubated in 20 mM D-glucose for 24 to 96 h, in the absence or presence of 100 µM homocysteine, with/without a hydrogen sulfide donor GYY4137, were analyzed for mitochondrial ROS (MitoSox fluorescence), DNA damage (transcripts of mtDNA-encoded ND6 and CytB), copy numbers, oxygen consumption rate (Seahorse XF analyzer) and mitophagy (mitophagosomes immunofluorescence labeling and flow cytometry). Results were confirmed in the retina from mice genetically manipulated for hyperhomocysteinemia (cystathionine β-synthase deficient mice, Cbs
    Results: Homocysteine, in high glucose medium, exacerbated mitochondrial ROS production, mtDNA damage and impaired mitochondrial respiration within 24 h, and slowed down/worsened mitochondrial biogenesis and mitophagy, as compared to 48 to 96 h in high glucose alone. GYY4137 supplementation ameliorated homocysteine + high glucose-induced mitochondrial damage and impairment in biogenesis and mitophagy. Similar results were obtained from Cbs
    Conclusions: Hyperhomocysteinemia, in a hyperglycemic environment, overwhelms the mitochondria, accelerating and exacerbating their dysfunction, and also delays/worsens their removal, augmenting the development of diabetic retinopathy. Thus, our results strengthen the importance of maintaining homocysteine-hydrogen sulfide balance during the early stages of diabetes for a patient to prevent/retard vision loss.
    Language English
    Publishing date 2024-01-16
    Publishing country England
    Document type Journal Article
    ZDB-ID 2806610-8
    ISSN 2326-0254
    ISSN 2326-0254
    DOI 10.1186/s40662-023-00362-1
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Long Noncoding RNAs and Mitochondrial Homeostasis in the Development of Diabetic Retinopathy.

    Kowluru, Renu A

    Frontiers in endocrinology

    2022  Volume 13, Page(s) 915031

    Abstract: Retinopathy is one of the most devastating complications of diabetes, which a patient fears the most. Hyperglycemic environment results in many structural, functional, molecular and biochemical abnormalities in the retina, and overproduction of ... ...

    Abstract Retinopathy is one of the most devastating complications of diabetes, which a patient fears the most. Hyperglycemic environment results in many structural, functional, molecular and biochemical abnormalities in the retina, and overproduction of mitochondrial superoxide, induced by hyperglycemic milieu, is considered to play a central role in the development of diabetic retinopathy. Expression of many genes associated with maintaining mitochondrial homeostasis is also altered. Recent research has shown that several long noncoding RNAs, RNAs with more than 200 nucleotides but without any reading frames, are aberrantly expressed in diabetes, and altered expression of these long noncoding RNAs is now being implicated in the development of diabetes and its complications including retinopathy. This review focuses the role of long noncoding RNAs in the development of diabetic retinopathy, with a special emphasis on the maintenance of mitochondrial homeostasis.
    MeSH term(s) Diabetes Mellitus/metabolism ; Diabetic Retinopathy/genetics ; Diabetic Retinopathy/metabolism ; Homeostasis/genetics ; Humans ; Mitochondria/genetics ; Mitochondria/metabolism ; RNA, Long Noncoding/genetics ; Retina/metabolism
    Chemical Substances RNA, Long Noncoding
    Language English
    Publishing date 2022-06-06
    Publishing country Switzerland
    Document type Journal Article ; Review ; Research Support, Non-U.S. Gov't ; Research Support, N.I.H., Extramural
    ZDB-ID 2592084-4
    ISSN 1664-2392
    ISSN 1664-2392
    DOI 10.3389/fendo.2022.915031
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Diabetic Retinopathy and NADPH Oxidase-2: A Sweet Slippery Road.

    Kowluru, Renu A

    Antioxidants (Basel, Switzerland)

    2021  Volume 10, Issue 5

    Abstract: Diabetic retinopathy remains the leading cause of vision loss in working-age adults. The multi-factorial nature of the disease, along with the complex structure of the retina, have hindered in elucidating the exact molecular mechanism(s) of this blinding ...

    Abstract Diabetic retinopathy remains the leading cause of vision loss in working-age adults. The multi-factorial nature of the disease, along with the complex structure of the retina, have hindered in elucidating the exact molecular mechanism(s) of this blinding disease. Oxidative stress appears to play a significant role in its development and experimental models have shown that an increase in cytosolic Reacttive Oxygen Speies (ROS) due to the activation of NADPH oxidase 2 (Nox2), is an early event, which damages the mitochondria, accelerating loss of capillary cells. One of the integral proteins in the assembly of Nox2 holoenzyme, Rac1, is also activated in diabetes, and due to epigenetic modifications its gene transcripts are upregulated. Moreover, addition of hyperlipidemia in a hyperglycemic milieu (type 2 diabetes) further exacerbates Rac1-Nox2-ROS activation, and with time, this accelerates and worsens the mitochondrial damage, ultimately leading to the accelerated capillary cell loss and the development of diabetic retinopathy. Nox2, a multicomponent enzyme, is a good candidate to target for therapeutic interventions, and the inhibitors of Nox2 and Rac1 (and its regulators) are in experimental or clinical trials for other diseases; their possible use to prevent/halt retinopathy will be a welcoming sign for diabetic patients.
    Language English
    Publishing date 2021-05-15
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2704216-9
    ISSN 2076-3921
    ISSN 2076-3921
    DOI 10.3390/antiox10050783
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  6. Article ; Online: Mitochondrial Quality Control and Metabolic Memory Phenomenon Associated with Continued Progression of Diabetic Retinopathy.

    Kowluru, Renu A / Alka, Kumari

    International journal of molecular sciences

    2023  Volume 24, Issue 9

    Abstract: Diabetic retinopathy continues to progress even when hyperglycemia is terminated, suggesting a 'metabolic memory' phenomenon. Mitochondrial dysfunction is closely associated with the development of diabetic retinopathy, and mitochondria remain ... ...

    Abstract Diabetic retinopathy continues to progress even when hyperglycemia is terminated, suggesting a 'metabolic memory' phenomenon. Mitochondrial dysfunction is closely associated with the development of diabetic retinopathy, and mitochondria remain dysfunctional. Quality control of mitochondria requires a fine balance between mitochondrial fission-fusion, removal of the damaged mitochondria (mitophagy) and formation of new mitochondria (biogenesis). In diabetes, while mitochondrial fusion protein (Mfn2) is decreased, fission protein (Drp1) is increased, resulting in fragmented mitochondria. Re-institution of normal glycemia fails to reverse mitochondrial fragmentation, and dysfunctional mitochondria continue to accumulate. Our aim was to investigate the direct effect of regulation of the mitochondrial fusion process during normal glycemia that follows a high glucose insult on mitochondrial quality control in the 'metabolic memory' phenomenon. Human retinal endothelial cells, incubated in 20 mM glucose for four days, followed by 5 mM glucose for four additional days, with or without the Mfn2 activator leflunomide, were analyzed for mitochondrial fission (live cell imaging), mitophagy (flow cytometry and immunofluorescence microscopy), and mitochondrial mass (mitochondrial copy numbers and MitoTracker labeling). Mitochondrial health was determined by quantifying mitochondrial reactive oxygen species (ROS), respiration rate (Seahorse XF96) and mitochondrial DNA (mtDNA) damage. Addition of leflunomide during normal glucose exposure that followed high glucose prevented mitochondrial fission, facilitated mitophagy and increased mitochondrial mass. Glucose-induced decrease in mitochondrial respiration and increase in ROS and mtDNA damage were also prevented. Thus, direct regulation of mitochondrial dynamics can help maintain mitochondrial quality control and interfere with the metabolic memory phenomenon, preventing further progression of diabetic retinopathy.
    MeSH term(s) Rats ; Animals ; Humans ; Diabetic Retinopathy/metabolism ; Reactive Oxygen Species/metabolism ; Endothelial Cells/metabolism ; Leflunomide/pharmacology ; Rats, Wistar ; Mitochondria/metabolism ; DNA, Mitochondrial/genetics ; Glucose/metabolism ; Mitochondrial Dynamics ; Diabetes Mellitus/metabolism
    Chemical Substances Reactive Oxygen Species ; Leflunomide (G162GK9U4W) ; DNA, Mitochondrial ; Glucose (IY9XDZ35W2)
    Language English
    Publishing date 2023-04-29
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms24098076
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Diabetic Retinopathy: Mitochondria Caught in a Muddle of Homocysteine.

    Kowluru, Renu A

    Journal of clinical medicine

    2020  Volume 9, Issue 9

    Abstract: Diabetic retinopathy is one of the most feared complications of diabetes. In addition to the severity of hyperglycemia, systemic factors also play an important role in its development. Another risk factor in the development of diabetic retinopathy is ... ...

    Abstract Diabetic retinopathy is one of the most feared complications of diabetes. In addition to the severity of hyperglycemia, systemic factors also play an important role in its development. Another risk factor in the development of diabetic retinopathy is elevated levels of homocysteine, a non-protein amino acid, and hyperglycemia and homocysteine are shown to produce synergistic detrimental effects on the vasculature. Hyperhomocysteinemia is associated with increased oxidative stress, and in the pathogenesis of diabetic retinopathy, oxidative stress-mitochondrial dysfunction precedes the development of histopathology characteristic of diabetic retinopathy. Furthermore, homocysteine biosynthesis from methionine forms S-adenosyl methionine (SAM), and SAM is a co-substrate of DNA methylation. In diabetes, DNA methylation machinery is activated, and mitochondrial DNA (mtDNA) and several genes associated with mitochondrial homeostasis undergo epigenetic modifications. Consequently, high homocysteine, by further affecting methylation of mtDNA and that of genes associated with mtDNA damage and biogenesis, does not give any break to the already damaged mitochondria, and the vicious cycle of free radicals continues. Thus, supplementation of sensible glycemic control with therapies targeting hyperhomocysteinemia could be valuable for diabetic patients to prevent/slow down the development of this sight-threatening disease.
    Language English
    Publishing date 2020-09-19
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2662592-1
    ISSN 2077-0383
    ISSN 2077-0383
    DOI 10.3390/jcm9093019
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Retinopathy in a Diet-Induced Type 2 Diabetic Rat Model and Role of Epigenetic Modifications.

    Kowluru, Renu A

    Diabetes

    2020  Volume 69, Issue 4, Page(s) 689–698

    Abstract: Type 2 diabetes accounts for 90% of the population with diabetes, and these patients are generally obese and hyperlipidemic. In addition to hyperglycemia, hyperlipidemia is also closely related with diabetic retinopathy. The aim was to investigate ... ...

    Abstract Type 2 diabetes accounts for 90% of the population with diabetes, and these patients are generally obese and hyperlipidemic. In addition to hyperglycemia, hyperlipidemia is also closely related with diabetic retinopathy. The aim was to investigate retinopathy in a model closely mimicking the normal progression and metabolic features of the population with type 2 diabetes and elucidate the molecular mechanism. Retinopathy was evaluated in rats fed a 45% kcal as fat diet for 8 weeks before administering streptozotocin, 30 mg/kg body weight (T2D), and compared with age- and duration-matched type 1 diabetic rats (T1D) (60 mg/kg streptozotocin). The role of epigenetic modifications in mitochondrial damage was evaluated in retinal microvasculature. T2D rats were obese and severely hyperlipidemic, with impaired glucose and insulin tolerance compared with age-matched T1D rats. While at 4 months of diabetes, T1D rats had no detectable retinopathy, T2D rats had significant retinopathy, their mitochondrial copy numbers were lower, and mtDNA and
    MeSH term(s) Animals ; DNA Methylation ; Diabetes Mellitus, Experimental/genetics ; Diabetes Mellitus, Experimental/metabolism ; Diabetes Mellitus, Type 2/etiology ; Diabetes Mellitus, Type 2/genetics ; Diabetes Mellitus, Type 2/metabolism ; Diabetic Retinopathy/genetics ; Diabetic Retinopathy/metabolism ; Diet, High-Fat/adverse effects ; Disease Models, Animal ; Epigenesis, Genetic ; Insulin Resistance/physiology ; Male ; Promoter Regions, Genetic ; Rats ; Rats, Sprague-Dawley
    Language English
    Publishing date 2020-01-16
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 80085-5
    ISSN 1939-327X ; 0012-1797
    ISSN (online) 1939-327X
    ISSN 0012-1797
    DOI 10.2337/db19-1009
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article: Mitochondrial Fragmentation in a High Homocysteine Environment in Diabetic Retinopathy.

    Kowluru, Renu A / Mohammad, Ghulam

    Antioxidants (Basel, Switzerland)

    2022  Volume 11, Issue 2

    Abstract: Diabetic patients routinely have elevated homocysteine levels, and due to increase in oxidative stress, hyperhomocysteinemia is associated with increased mitochondrial damage. Mitochondrial homeostasis is directly related to the balance between their ... ...

    Abstract Diabetic patients routinely have elevated homocysteine levels, and due to increase in oxidative stress, hyperhomocysteinemia is associated with increased mitochondrial damage. Mitochondrial homeostasis is directly related to the balance between their fission and fusion, and in diabetes this balance is disturbed. The aim of this study was to investigate the role of homocysteine in mitochondrial fission in diabetic retinopathy. Human retinal endothelial cells, either untransfected or transfected with siRNA of a fission protein (dynamin-related protein 1, Drp1) and incubated in the presence of 100 μM homocysteine, were analyzed for mitochondrial fragmentation by live-cell microscopy and GTPase activity of Drp1. Protective nucleoids and mtDNA damage were evaluated by SYBR DNA stain and by transcripts of mtDNA-encoded
    Language English
    Publishing date 2022-02-11
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2704216-9
    ISSN 2076-3921
    ISSN 2076-3921
    DOI 10.3390/antiox11020365
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Mitochondrial Dynamics in the Metabolic Memory of Diabetic Retinopathy.

    Mohammad, Ghulam / Kowluru, Renu A

    Journal of diabetes research

    2022  Volume 2022, Page(s) 3555889

    Abstract: Mitochondria play a central role in the development of diabetic retinopathy and in the metabolic memory associated with its continued progression. Mitochondria have a regulated fusion fission process, which is essential for their homeostasis. One of the ... ...

    Abstract Mitochondria play a central role in the development of diabetic retinopathy and in the metabolic memory associated with its continued progression. Mitochondria have a regulated fusion fission process, which is essential for their homeostasis. One of the major fission proteins, dynamin-related protein 1 (Drp1), is recruited to the mitochondria by fission protein 1 (Fis1) to initiate fragmentation. Our aim is to investigate the role of Drp1 in the altered mitochondrial dynamics in the continued progression of diabetic retinopathy.
    MeSH term(s) Animals ; Diabetes Mellitus, Experimental/metabolism ; Diabetic Retinopathy/metabolism ; Endothelial Cells/metabolism ; Glucose/pharmacology ; Mitochondrial Dynamics ; Mitochondrial Proteins/genetics ; Mitochondrial Proteins/metabolism ; Rats
    Chemical Substances Mitochondrial Proteins ; Glucose (IY9XDZ35W2)
    Language English
    Publishing date 2022-03-31
    Publishing country England
    Document type Journal Article
    ZDB-ID 2711897-6
    ISSN 2314-6753 ; 2314-6753
    ISSN (online) 2314-6753
    ISSN 2314-6753
    DOI 10.1155/2022/3555889
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