4 results on '"Konstantinou EK"'
Search Results
2. Acadesine suppresses TNF-α induced complement component 3 (C3), in retinal pigment epithelial (RPE) cells.
- Author
-
Efstathiou NE, Moustafa GA, Maidana DE, Konstantinou EK, Notomi S, Barbisan PRT, Georgakopoulos CD, Miller JW, and Vavvas DG
- Subjects
- AMP-Activated Protein Kinases metabolism, Adenosine metabolism, Aminoimidazole Carboxamide metabolism, Aminoimidazole Carboxamide pharmacology, Animals, Cell Line, Cells, Cultured, Complement Activation drug effects, Complement C3 drug effects, Humans, Macular Degeneration metabolism, Phosphorylation, Retinal Pigment Epithelium drug effects, Retinal Pigments metabolism, Ribonucleosides metabolism, Ribonucleotides pharmacology, Tumor Necrosis Factor-alpha metabolism, Aminoimidazole Carboxamide analogs & derivatives, Complement C3 metabolism, Retinal Pigment Epithelium metabolism, Ribonucleosides pharmacology
- Abstract
Rationale: Age-related macular degeneration (AMD) is the most prevalent form of irreversible blindness in the developed world. Aging, inflammation and complement dysregulation affecting the retinal pigment epithelium (RPE), are considered significant contributors in its pathogenesis and several evidences have linked tumor necrosis factor alpha (TNF-α) and complement component 3 (C3) with AMD. Acadesine, an analog of AMP and an AMP-activated protein kinase (AMPK) activator, has been shown to have cytoprotective effects in human clinical trials as well as having anti-inflammatory and anti-vascular exudative effects in animals. The purpose of this study was to evaluate if acadesine is able to suppress TNF-α induced C3 in RPE cells., Methods: ARPE-19 and human primary RPE cells were cultured and allowed to grow to confluence. TNF-α was used for C3 induction in the presence or absence of acadesine. Small molecule inhibitors and siRNA were used to determine if acadesine exerts its effect via the extracellular or intracellular pathway and to evaluate the importance of AMPK for these effects. The expression level of C3 was determined by immunoblot analysis., Results: Acadesine suppresses TNF-α induced C3 in a dose dependent manner. When we utilized the adenosine receptor inhibitor dipyridamole (DPY) along with acadesine, acadesine's effects were abolished, indicating the necessity of acadesine to enter the cell in order to exert it's action. However, pretreatment with 5-iodotubericidin (5-Iodo), an adenosine kinase (AK) inhibitor, didn't prevent acadesine from decreasing TNF-α induced C3 expression suggesting that acadesine does not exert its effect through AMP conversion and subsequent activation of AMPK. Consistent with this, knockdown of AMPK α catalytic subunit did not affect the inhibitory effect of acadesine on TNF-α upregulation of C3., Conclusions: Our results suggest that acadesine suppresses TNF-α induced C3, likely through an AMPK-independent pathway, and could have potential use in complement over activation diseases., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2020
- Full Text
- View/download PDF
3. Issues with the Specificity of Immunological Reagents for NLRP3: Implications for Age-related Macular Degeneration.
- Author
-
Kosmidou C, Efstathiou NE, Hoang MV, Notomi S, Konstantinou EK, Hirano M, Takahashi K, Maidana DE, Tsoka P, Young L, Gragoudas ES, Olsen TW, Morizane Y, Miller JW, and Vavvas DG
- Subjects
- Alu Elements, Animals, Antibody Specificity, Cell Line, DEAD-box RNA Helicases genetics, Disease Models, Animal, Gene Deletion, Humans, Induced Pluripotent Stem Cells cytology, Induced Pluripotent Stem Cells metabolism, Macular Degeneration genetics, Mice, Retinal Pigment Epithelium cytology, Ribonuclease III genetics, THP-1 Cells, Antibodies analysis, Macular Degeneration immunology, NLR Family, Pyrin Domain-Containing 3 Protein immunology, Retinal Pigment Epithelium metabolism
- Abstract
Contradictory data have been presented regarding the implication of the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome in age-related macular degeneration (AMD), the leading cause of vision loss in the Western world. Recognizing that antibody specificity may explain this discrepancy and in line with recent National Institutes of Health (NIH) guidelines requiring authentication of key biological resources, the specificity of anti-NLRP3 antibodies was assessed to elucidate whether non-immune RPE cells express NLRP3. Using validated resources, NLRP3 was not detected in human primary or human established RPE cell lines under multiple inflammasome-priming conditions, including purported NLRP3 stimuli in RPE such as DICER1 deletion and Alu RNA transfection. Furthermore, NLRP3 was below detection limits in ex vivo macular RPE from AMD patients, as well as in human induced pluripotent stem cell (hiPSC)-derived RPE from patients with overactive NLRP3 syndrome (Chronic infantile neurologic cutaneous and articulate, CINCA syndrome). Evidence presented in this study provides new data regarding the interpretation of published results reporting NLRP3 expression and upregulation in RPE and addresses the role that this inflammasome plays in AMD pathogenesis.
- Published
- 2018
- Full Text
- View/download PDF
4. AICAR suppresses TNF-α-induced complement factor B in RPE cells.
- Author
-
Chung EJ, Efstathiou NE, Konstantinou EK, Maidana DE, Miller JW, Young LH, and Vavvas DG
- Subjects
- Aminoimidazole Carboxamide metabolism, Cell Line, Clustered Regularly Interspaced Short Palindromic Repeats, Complement Activation, Dipyridamole pharmacology, Humans, Phosphotransferases (Phosphate Group Acceptor) genetics, Tubercidin analogs & derivatives, Tubercidin pharmacology, Tumor Necrosis Factor-alpha metabolism, Aminoimidazole Carboxamide analogs & derivatives, Complement Factor B metabolism, Macular Degeneration metabolism, Phosphotransferases (Phosphate Group Acceptor) metabolism, Retinal Pigment Epithelium physiology, Ribonucleosides metabolism
- Abstract
Age related macular degeneration is the leading cause of blindness in the developed world. Although its precise cause remains elusive, dysfunction of the retinal pigment epithelium (RPE) and dysregulation of complement have been implicated in its pathogenesis. The goal of this study was to evaluate the role of an AMP-dependent kinase (AMPK) activator, 5-aminoimidazole-4-carboxamide riboside (AICAR), on tumor necrosis factor alpha (TNF-α) induction of complement factor B (CFB) in RPE cells. We found that AICAR inhibited TNF-α-induced CFB expression in ARPE-19 and human primary RPE cells in a dose-dependent fashion. Treatment of cells with dipyridamole, which blocks AICAR cellular uptake abolished these effects. In contrast, the adenosine kinase inhibitor, 5-iodotubericidin, which inhibits the conversion of AICAR to the direct activator of AMPK, ZMP, did not reverse the effects on TNF-α-induced CFB expression, suggesting AMPK-independent effects. Indeed, knockout of AMPK in RPE cells using Clustered Regularly Interspaced Palindromic Repeats (CRISPR)/Cas9 did not abolish the inhibitory effects of AICAR on RPE CFB expression. Collectively, our results suggest that AICAR can suppress TNF-α-induced CFB expression in RPE cells in an AMPK-independent mechanism, and could be used as a therapeutic target in certain complement over-activation scenarios.
- Published
- 2017
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.