Inflammation‐Induced TLR4 Expression and Reactive Oxygen Species are Attenuated by Dihydrotestosterone in Human Primary Vascular Smooth Muscle Cells

Our previous data have shown that dihydrotestosterone (DHT) attenuates endotoxin and oxygen glucose deprivation (OGD)‐induced cyclooxygenase‐2 (COX‐2) in human vascular smooth muscle (VSM) cells. COX‐2 plays a role in vascular inflammation and has been implicated as a source of reactive oxygen species (ROS). In rats, androgens have been shown to be protective during cerebral ischemia and to decrease oxidative stress in vascular tissues. Because TLR4 has been implicated in injury‐induced oxidation, we hypothesized that chronic DHT treatment (10nM) alleviates oxidative stress by attenuating TLR4 expression and decreasing ROS following endotoxin, hypoxia, or OGD in primary human VSM cells. TLR4 localization was detected via confocal microscopy, TLR4 protein levels were measured via western blot, and ROS generation was measured using the indicator dye carboxy‐H 2 DCFDA. Endotoxin, hypoxia, and OGD all increased TLR4 expression compared to controls. In contrast, endotoxin and OGD‐induced TLR4 expression was attenuated in the presence of DHT. In the OGD studies, DHT's effect on TLR4 was androgen receptor independent. Similar to the TLR4 studies, cytokine‐induced ROS production was blunted by DHT. Thus in conditions of oxidative stress, androgens may confer protection from vascular injury in part by attenuating both TLR4 expression and ROS production. Sarver Heart Center and AHA (RG & KO)