Fig. 3.

Conditioned medium from IL-1β- or CSE-activated primary HLFs contains peroxisome proliferator-activated receptor (PPAR)-γ (PPARγ) ligands. Primary HLFs were treated for 72 h with 0, 0.1, or 1 ng/ml IL-1β (A) or for 24 h with 0, 16.25, or 32.5 OD₃₂₀ U/ml CSE (B) and then washed with 1× PBS and incubated in fresh medium for another 48 h before conditioned medium was harvested. Conditioned media were transferred to HEK 293FT cells transiently transfected with PPARγ with or without a PPAR response element (PPRE)-luciferase (Luc) reporter plasmid (see materials and methods). Conditioned media of HLFs activated with IL-1β (A) or CSE (B) activated the PPRE-luciferase reporter, indicating the presence of PPARγ ligands. Rosiglitazone (100 nM), a potent synthetic PPARγ agonist, was used as a positive control in all reporter assays (C). IL-1β alone did not activate the PPRE-luciferase reporter (data not shown). Values are means ± SD of 3 independent biological replicates per condition. *P < 0.05, **P < 0.01, ****P < 0.0001 (by unpaired t-test). Utr, untreated; Veh, vehicle.