High glucose-induced phospholipase D activity in retinal pigment epithelium cells: New insights into the molecular mechanisms of diabetic retinopathy

TENCONI, PAULA E.; BERMÚDEZ, VICENTE; ORESTI, GERARDO M.; GIUSTO, NORMA M.; SALVADOR, GABRIELA A.; MATEOS, MELINA V.

EXPERIMENTAL EYE RESEARCH

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2019 vol. 184 p. 243 - 257

0014-4835

Chronic hyperglycemia, oxidative stress and inflammation are key players in the pathogenesis of diabetic retinopathy (DR). In this work we study the role of phospholipase D (PLD)pathway in an in vitro model of high glucose (HG)-induced damage. To this end, we exposed human retinal pigment epithelium (RPE)cell lines (ARPE-19 and D407)to HG concentrations (16.5 or 33 mM)or to normal glucose concentration (NG, 5.5 mM)for 4, 24 or 72 h. Exposure to HG increased reactive oxygen species levels and caspase-3 cleavage and reduced cell viability after 72 h of incubation. In addition, short term HG exposure (4 h)induced the activation of early events, that involve PLD and ERK1/2 signaling, nuclear factor kappa B (NFκB)nuclear translocation and IκB phosphorylation. The increment in pro-inflammatory interleukins (IL-6 and IL-8)and cyclooxygenase-2 (COX-2)mRNA levels was observed after 24 h of HG exposure. The effect of selective pharmacological PLD1 (VU0359595)and PLD2 (VU0285655-1)inhibitors demonstrated that ERK1/2 and NFκB activation were downstream events of both PLD isoforms. The increment in IL-6 and COX-2 mRNA levels induced by HG was reduced to control levels in cells pre-incubated with both PLD inhibitors. Furthermore, the inhibition of PLD1, PLD2 and MEK/ERK pathway prevented the loss of cell viability and the activation of caspase-3 induced by HG. In conclusion, our findings demonstrate that PLD1 and PLD2 mediate the inflammatory response triggered by HG in RPE cells, pointing to their potential use as a therapeutic target for DR treatment.