Vitamin D Protects against Oxidative Stress and Inflammation in Human Retinal Cells

Abstract

Diabetic retinopathy is a vision-threatening microvascular complication of diabetes and is one of the leading causes of blindness. Oxidative stress and inflammation play a major role in its pathogenesis, and new therapies counteracting these contributors could be of great interest. In the current study, we investigated the role of vitamin D against oxidative stress and inflammation in human retinal pigment epithelium (RPE) and human retinal endothelial cell lines. We demonstrate that vitamin D effectively counteracts the oxidative stress induced by hydrogen peroxide (H2O2). In addition, the increased levels of proinflammatory proteins such as Interleukin (IL)-6, IL-8, Monocyte chemoattractant protein (MCP)-1, Interferon (IFN)-γ, and tumor necrosis factor (TNF)-α triggered by lipopolysaccharide (LPS) exposure were significantly decreased by vitamin D addition. Interestingly, the increased IL-18 only decreased by vitamin D addition in endothelial cells but not in RPE cells, suggesting a main antiangiogenic role under inflammatory conditions. Moreover, H2O2 and LPS induced the alteration and morphological damage of tight junctions in adult retinal pigment epithelium (ARPE-19) cells that were restored under oxidative and inflammatory conditions by the addition of vitamin D to the media. In conclusion, our data suggest that vitamin D could protect the retina by enhancing antioxidant defense and through exhibiting anti-inflammatory properties.

Anti-Inflammatory and Anti-Oxidative Synergistic Effect of Vitamin D and Nutritional Complex on Retinal Pigment Epithelial and Endothelial Cell Lines against Age-Related Macular Degeneration

“…The same cell lines and culture system were used as previously described [ 36 ]. Briefly, human retinal pigment epithelial cells, ARPE-19 (CRL-2302, ATCC, Manassas, VG, USA; 3 passages) were grown to confluence in a standard incubator in DMEM (D6429, Sigma-Aldrich, St Louis, MO, USA) containing 10% fetal bovine serum (FBS; 10270106 Gibco TM ThermoFisher, Paisley, UK), 1% fungizone (Gibco TM ), and penicillin–streptomycin (Gibco TM ).…”

“…As previously described [ 36 ], immunofluorescence with RPE65 (1:100, 78036, Abcam, Cambridge, USA) and caveolin (1:250, 3238S, Cell Signalling, Danvers, MA, USA) was performed for ARPE-19 and HREC cells, respectively. Briefly, 100,000 ARPE-19 and 50,000 HREC cells were seeded on a 10 mm dish (Menzel-Glaser, Waltham, MA, USA) and following cellular fixation with cold methanol, cells were blocked with 1% BSA, 0.5% Triton X-100, 0.2% sodium azide, and 1% FBS for 1 h at 4 °C.…”

“…Recent studies have reported expression of vitamin D receptors throughout the eye, including the retina [ 31 , 32 ], where they are expressed by human retinal pigment epithelial cells (ARPE-19) [ 31 , 33 ] and retinal endothelial cells [ 34 ], suggesting vitamin D’s functional significance in the ocular system [ 35 ]. Moreover, a recent study has reported expression of vitamin D-synthesizing components in ARPE-19 and HREC cells [ 36 ]. The expression of vitamin D receptors in RPE cells has been previously demonstrated by our group, using PCR experiments [ 36 ], and by other investigators who demonstrated by immunohistochemical staining presence of vitamin D receptors throughout the RPE [ 37 ] as well as by whole-transcriptome expression profiles in the RPE–choroid region collected from human donors [ 38 ] .…”

“…Moreover, a recent study has reported expression of vitamin D-synthesizing components in ARPE-19 and HREC cells [ 36 ]. The expression of vitamin D receptors in RPE cells has been previously demonstrated by our group, using PCR experiments [ 36 ], and by other investigators who demonstrated by immunohistochemical staining presence of vitamin D receptors throughout the RPE [ 37 ] as well as by whole-transcriptome expression profiles in the RPE–choroid region collected from human donors [ 38 ] .…”

Oxidative Stress in Diabetic Retinopathy

“…The first five manuscripts discuss in vitro approximations. Fernández-Robredo et al report results showing the antioxidant and anti-inflammatory properties of vitamin D, suggesting its usefulness in moderating the chronic low-grade inflammation and oxidative stress in the development of DR [ 15 ]. Oh et al show the antioxidant capacity of two supplements, ascorbic acid and astaxanthin, using two different oxidative models on a human retinal pigment epithelia cell line (ARPE-19) [ 16 ].…”