Losartan diminishes expression of OA-related genes through PPARγ-mediated TGF-β1/Smad2/3 signaling pathway inactivation in chondrocytes. Normal chondrocytes were used as controls, and OA chondrocytes were treated with or without losartan + PBS or losartan + TGF-β1. A, Expression of PPARγ, TGF-β1, Smad2, and Smad3, along with the extent of Smad2 and Smad3 phosphorylation in chondrocytes evaluated by Western blot analysis normalized to GAPDH. B, Expression of MMP-13, ADAMTS-4, ADAMTS-5, HtrA1, iNOS, and Collagen II in chondrocytes evaluated by Western blot analysis normalized to GAPDH. C, The levels of IL-6, IL-1β, TNF-α, and COX-2 in chondrocytes evaluated by ELISA. OA chondrocytes were treated with losartan + PPARγ siRNA + PBS or losartan + PPARγ siRNA + TGF-β1. D, Expression of PPARγ, TGF-β1, Smad2, and Smad3, along with the extent of Smad2 and Smad3 phosphorylation in chondrocytes evaluated by Western blot analysis normalized to GAPDH. E, Expression of MMP-13, ADAMTS-4, ADAMTS-5, HtrA1, iNOS, and Collagen II in chondrocytes evaluated by Western blot analysis normalized to GAPDH. F, The levels of IL-6, IL-1β, TNF-α, and COX-2 in chondrocytes evaluated by ELISA. The experiment was repeated three times. ∗p < 0.05 vs. control chondrocytes or OA chondrocytes treated with losartan + PPARγ siRNA + PBS; #p < 0.05 vs. OA chondrocytes treated with losartan + PBS.