Abstract
Aims
There is clinical evidence that fenofibrate, a PPARα agonist, arrests the progression of diabetic macular edema (DME). However, the underlying mechanisms of this beneficial effect remain to be elucidated. We previously reported that fenofibric acid (FA), the active metabolite of fenofibrate, prevents the disorganization of tight junction proteins and the hyperpermeability provoked by the diabetic milieu in the retinal pigment epithelium (RPE). The aim of the present study was to evaluate whether this effect is mediated by inhibiting the proinflammatory transcription factor NF-κB, as well as the expression of several proinflammatory cytokines involved in the pathogenesis of DME.
Methods
Human RPE cells were cultured under standard conditions and under conditions leading to the disruption of the monolayer [IL-1β (10 ng/ml)]. The effect of FA, QNZ (a NF-κB inhibitor), WY14643 (a PPARα agonist), and MK-866 (a PPARα antagonist) in the disruption of the monolayer was determined by dextran permeability and immunohistochemistry analyses. The effect of FA on NF-κB activity was assessed by EMSA and by NF-κB/p65 nuclear translocation analyses. The expression of cytokines (IL-6, IL-8, MCP-1) was measured by RT-PCR.
Results
FA prevented RPE monolayer disruption, and the consequent hyperpermeability induced by IL-1β, through inhibition of NF-κB activity. This effect was due to PPARα activation and was associated with a significant downregulation of the expression of proinflammatory cytokines.
Conclusions
Our findings suggest that the anti-inflammatory effects of FA through inhibition of NF-κB activity play a key role in the beneficial effect of fenofibrate for treating DME.
Similar content being viewed by others
References
Klein R, Klein BEK, Moss SE, Cruickshanks KJ (1995) The Wisconsin epidemiologic study of diabetic retinopathy: XV: the long-term incidence of macular edema. Ophthalmology 102:7–16
Congdom N, Friedman DS, Lietman T (2006) Important causes of visual impairment in the world today. JAMA 290:2057–2060
Yau JW, Rogers SL, Kawasaki R et al (2012) Global prevalence and major risk factors of diabetic retinopathy. Diabetes Care 35:556–564
Rosenson RS (2008) Fenofibrate: treatment of hyperlipidemia and beyond. Expert Rev Cardiovasc Ther 6:1319–1330
Keech AC, Mitchell P, Summanen PA et al (2007) Effect of fenofibrate on the need for laser treatment for diabetic retinopathy (FIELD study): a randomised controlled trial. Lancet 370:1687–1697
Simó R, Hernández C (2007) Fenofibrate for diabetic retinopathy. Lancet 370:1667–1668
Wong TY, Simó R, Mitchell P (2012) Fenofibrate—a potential systemic treatment for diabetic retinopathy? Am J Ophthalmol 154:6–12
Simo R, Roy S, Behar-Cohen F, Keech A, Mitchell P, Wong TY (2013) Fenofibrate: a new treatment for diabetic retinopathy. Molecular mechanisms and future perspectives. Curr Med Chem 20:3258–3266
Simo R, Villarroel M, Corraliza L, Hernandez C, Garcia-Ramírez M (2010) The retinal pigment epithelium: something more than a constituent of the blood-retinal barrier–implications for the pathogenesis of diabetic retinopathy. J Biomed Biotechnol 52:2160–2164
Trudeau K, Roy S, Guo W et al (2011) Fenofibric acid reduces fibronectin and collagen type IV overexpression in human retinal pigment epithelial cells grown in conditions mimicking the diabetic milieu: functional implications in retinal permeability. Invest Ophthalmol Vis Sci 52:6348–6354
Miranda S, González-Rodríguez A, Garcia-Ramírez M et al (2012) Beneficial effects of fenofibrate in retinal pigment epithelium by the modulation of stress and survival signaling under diabetic conditions. J Cell Physiol 227:2352–2362
Villarroel M, Garcia-Ramírez M, Corraliza L, Hernandez C, Simo R (2011) Fenofibric acid prevents retinal pigment epithelium disruption induced by interleukin-1β by suppressing AMP-activated protein kinase (AMPK) activation. Diabetologia 54:1543–1553
Joussen A, Smyth N, Niessen C (2007) Pathophysiology of diabetic macular edema. Dev Ophthalmol 39:1–12
Frey T, Antonetti DA (2011) Alterations to the blood-retinal barrier in diabetes: cytokines and reactive oxygen species. Antioxid Redox Signal 15:1271–1284
Salminen A, Hyttinen JM, Kaarniranta K (2011) AMP-activated protein kinase inhibits NF-κB signaling and inflammation: impact on healthspan and lifespan. J Mol Med (Berl) 89:667–676
Garcia-Ramírez M, Villarroel M, Corraliza L, Hernandez C, Simo R (2011) Measuring permeability in human retinal epithelial cells (ARPE-19): implications for the study of diabetic retinopathy. Methods Mol Biol 763:179–194
Andrews NC, Faller DV (1991) A rapid micropreparation technique for extraction of DNA-binding proteins from limiting numbers of mammalian cells. Nucleic Acid Res 19:2499
Villarroel M, Garcia-Ramírez M, Corraliza L, Hernandez C, Simo R (2009) Effects of high glucose concentration on the barrier function and the expression of tight junction proteins in human retinal pigment epithelial cells. Exp Eye Res 89:913–920
Weinberger D, Fink-Cohen S, Gaton DD, Priel E, Yassur Y (1995) Non-retinovascular leakage in diabetic maculopathy. Br J Ophthalmol 79:728–731
Do Carmo A, Ramos P, Reis A, Proença R, Cunha-Vaz JG (1998) Breakdown of the inner and outer blood retinal barrier in streptozotocin-induced diabetes. Exp Eye Res 67:569–575
Kowalczuk L, Touchard E, Omri S et al (2011) Placental growth factor contributes to micro-vascular abnormalization and blood-retinal barrier breakdown in diabetic retinopathy. PLoS One 6:e17462
Xu HZ, Le YZ (2011) Significance of outer blood-retina barrier breakdown in diabetes and ischemia. Invest Ophthalmol Vis Sci 52:2160–2164
Cunha-Vaz J, Bernardes R, Lobo C (2011) Blood-retinal barrier. Eur J Ophthalmol 21(Suppl 6):S3–S9
Belfort R, Berria R, Cornell J, Cusi K (2010) Fenofibrate reduces systemic inflammation markers independent of its effects on lipid and glucose metabolism in patients with the metabolic syndrome. J Clin Endocrinol Metab 95:829–836
Okayasu T, Tomizawa A, Suzuki K, Manaka K, Hattori Y (2008) PPARalpha activators upregulate eNOS activity and inhibit cytokine-induced NF-kappaB activation through AMP-activated protein kinase activation. Life Sci 82:884–891
Tomizawa A, Hattori Y, Inoue T, Hattori S, Kasai K (2011) Fenofibric acid suppresses microvascular inflammation and apoptosis through adenosine monophosphate-activated protein kinase activation. Metabolism 60:513–522
Ji YY, Liu JT, Liu N, Wang ZD, Liu CH (2009) PPAR alpha activator fenofibrate modulates angiotensin II-induced inflammatory responses in vascular smooth muscle cells via the TLR4-dependent signaling pathway. Biochem Pharmacol 78:1186–1197
Chen Y, Hu Y, Lin M et al (2013) Therapeutic effects of PPARα agonists on diabetic retinopathy in type 1 diabetes models. Diabetes 62:261–272
Wang XC, Jobin C, Allen JB, Roberts W, Jaffe GJ (1999) Suppression of NF-kB-dependent proinflammatory gene expression in human RPE cells by a proteasome inhibitor. Investig Ophthalmol Vis Sci 40:477–486
Yang P, McKay BS, Allen JB, Roberts WL, Jaffe GJ (2003) Effect of mutant IκB on cytokine-induced activation of NF-κB in cultured human RPE cells. Invest Ophthalmol Vis Sci 44:1339–1347
Kowluru RA, Odenbach S (2004) Role of interleukin-1beta in the pathogenesis of diabetic retinopathy. Br J Ophthalmol 88:1343–1347
Kern TS (2007) Contributions of inflammatory processes to the development of early stages of diabetic retinopathy. Exp Diabetes Res 2007:95103
Simo-Servat O, Hernandez C, Simo R (2012) Usefulness of the vitreous fluid analysis in the translational research of diabetic retinopathy. Mediat Inflamm. 2012:872978
Ciudin A, Hernandez C, Simo R (2013) Molecular implications of the PPARs in the diabetic eye. PPAR Res 2013:686525
Hu Y, Chen Y, Ding L et al (2013) Pathogenic role of diabetes-induced PPAR-α down-regulation in microvascular dysfunction. Proc Natl Acad Sci USA 110:15401–15406
Acknowledgments
We thank Abbott for providing us with fenofibric acid (FA). This study was supported by grants from the Generalitat de Catalunya (2014-SGR-270), the Spanish Ministerio de Economía y Competitividad (SAF2012-30708), European Union ERDF funds, and from CIBERDEM (CIBER de Diabetes y Enfermedades Metabólicas Asociadas). CIBERDEM is an initiative of the Instituto de Salud Carlos III.
Conflict of interest
None.
Human and Animal Rights
This article does not contain any studies with human or animal subjects performed by any of the authors.
Informed consent
Informed consent was obtained from all individual participants included in the study.
Author information
Authors and Affiliations
Corresponding author
Additional information
Managed by Massimo Federici.
Marta Garcia-Ramírez and Cristina Hernández have contributed equally to this work.
Rights and permissions
About this article
Cite this article
Garcia-Ramírez, M., Hernández, C., Palomer, X. et al. Fenofibrate prevents the disruption of the outer blood retinal barrier through downregulation of NF-κB activity. Acta Diabetol 53, 109–118 (2016). https://doi.org/10.1007/s00592-015-0759-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00592-015-0759-3