Effect of LPS, PA and LPS plus PA on ceramide de novo synthesis and Sphingomyelin (SM) hydrolysis. The effect of LPS, PA or LPS plus PA on cellular ceramide level. HMC3 were treated with 100 ng/ml of LPS, 200 μM of palmitate or LPS plus PA for 12 or 24 h and lipidomic analysis was conducted to quantify the cellular total (A), C16- (B), dhC16- (C), C18- (D), C22- (E) ceramide, total SM (F), C16-SM (G), C22-SM (H), C24:1-SM (I), C24-SM (J), Sph (K), dhSph (L), S1P (M), and S1P (N) levels. The data presented are mean ± SEM of duplicate samples. ○:Ctl,□:LPS, ■:PA,●: LPS/PA. Values are expressed as means ± SEM. ∗p < 0.05, ∗∗p < 0.01 and ∗∗∗p < 0.001.