Abstract
Purpose:
Environmental tobacco smoke (ETS) is widely regarded as a major modifiable risk factor for age-related macular degeneration (AMD). Yet, precisely how it exerts its pathological effects is poorly understood. Since early-stage AMD is characterized by choroidal capillary loss, this study examined the effect of sidestream smoke (SS), the major component of ETS, on the viability of choroidal endothelial cells (EC), with an emphasis on the role of aberrant cell and basement membrane (BM) architecture in mediating SS-induced response.
Methods:
Chorioretinal ECs (RF/6A) were treated with SS and cell viability and architecture were analyzed by colorimetric assay and actin cytoskeletal organization, respectively. The structure of RF/6A EC-secreted BM was examined by immunofluorescence for collagen IV and immunoblotting for lysyl oxidase (LOX), a collagen-crosslinking enzyme. Finally, fresh RF/6A ECs were cultured on decellularized SS-treated BM to evaluate its active role in EC dysfunction.
Results:
RF/6A EC viability decreased progressively with increasing SS dose, which correlated strongly with a significant decline in actin cytoskeleton-dependent EC spreading. SS also caused marked disruption of RF/6A EC-secreted BM that was accompanied by suppression of LOX expression. Further, fresh, non SS-treated RF/6A ECs exhibited a significant loss in viability and actin cytoskeletal organization when cultured on SS-treated corrupt BM.
Conclusions:
These findings indicate that aberrant physical cues in the form of EC and BM architecture likely play an important role in choriocapillaris dysfunction seen in SS-associated early AMD, and implicate choroidal BM as a potential target for AMD management strategies.
Keywords: 412 age-related macular degeneration •
519 extracellular matrix •
636 pathobiology