CB1R blockade and CB2R activation affected the pro-fibrotic phenotype of M1 macrophages. (A) Mesangial cells were exposed for 48 h to CM from M1 macrophages pre-exposed for 24 h to vehicle (CM), AM6545 (CM^AM6545), AM1241 (CM^AM1241) or both (CM^A+A), then fibronectin mRNA levels were measured by real-time PCR. *P < 0.05, M1, M1-AM6545, M1-AM1241 versus vehicle; **P < 0.05, M1-AM6545, M1-AM1241 versus M1; ***P < 0.05, M1-A + A versus M1-AM6545 and M1-AM1241. (B) Total RNA was extracted from M1 macrophages and TNF-α mRNA levels measured by real-time PCR. *P < 0.05, AM1241, AM6545, A + A versus vehicle; ***P < 0.05, AM6545 and A + A versus AM1241. (C) Fibronectin mRNA expression in mesangial cells incubated with CM from M1 macrophages in the presence and in the absence of a neutralizing TNF-α antibody. *P < 0.05, M1 versus others.