2-ethylpyridine, a cigarette smoke component, causes mitochondrial damage in human retinal pigment epithelial cells in vitro.
OBJECTIVE
Our goal was to identify the cellular and molecular effects of 2-ethylpyridine (2-EP, a component of cigarette smoke) on human retinal pigment epithelial cells (ARPE-19) in vitro.


METHODS
ARPE-19 cells were exposed to varying concentrations of 2-EP. Cell viability (CV) was measured by a trypan blue dye exclusion assay. Caspase-3/7 and caspase-9 activities were measured by fluorochrome assays. The production of reactive oxygen/nitrogen species (ROS/RNS) was detected with a 2',7'-dichlorodihydrofluorescein diacetate dye assay. The JC-1 assay was used to measure mitochondrial membrane potential (ΔΨm). Mitochondrial redox potential was measured using a RedoxSensor Red kit and mitochondria were evaluated with Mitotracker dye.


RESULTS
After 2-EP exposure, ARPE-19 cells showed significantly decreased CV, increased caspase-3/7 and caspase-9 activities, elevated ROS/RNS levels, decreased ΔΨm value and decreased redox fluorescence when compared with control samples.


CONCLUSIONS
These results show that 2-EP treatment induced cell death by caspase-dependent apoptosis associated with an oxidative stress and mitochondrial dysfunction. These data represent a possible mechanism by which smoking contributes to age-related macular degeneration and other retinal diseases and identify mitochondria as a target for future therapeutic interventions.
S
S
Mansoor
N
N
Gupta
P
P
Falatoonzadeh
B D
BD
Kuppermann
Gavin Herbert Eye Institute, School of Medicine; Department of Pathology and Laboratory Medicine, University of California Irvine, Irvine, CA, USA, .
M C
MC
Kenney
D017209:Apoptosis; D002470:Cell Survival; D002478:Cells, Cultured; D006801:Humans; D008268:Macular Degeneration / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D011725:Pyridines / Q000009:adverse effects* / Q000032:analysis; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000473:pathology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D011725:Pyridines; D014028:Tobacco Smoke Pollution; C051672:2-ethylpyridine