Figure 2. The effects of E. coli LPS on IL-6 production, and of pioglitazone on E. coli LPS-induced IL-6 production in adipocytes. Mouse 3T3-L1 adipocytes were differentiated in 24-well tissue culture plates as described in MATERIALS & METHODS. After confirming the maturation of adipocity by staining the cells with oil red O, we stimulated the cells with indicated concentrations of E. coli LPS. In some cultures, the cells were co-incubated with 10 µM of pioglitazone. Twenty-four hrs later, the cell-culture supernatants were harvested, and the IL-6 concentration was measured by ELISA. All experiments were done in triplicate, and statistical differences were calculated by Student’s t test. In pioglitazone-treated cells, IL-6 production was compared with that of untreated cells when stimulated with the identical concentration of E. coli LPS. Mean IL-6 concentration ± standard deviation in each culture condition was calculated (1094.2 ± 68.6 pg/mL for LPS-unstimulated cells, 3189.7 ± 77.7 for 1 ng/mL of LPS-stimulated cells, 3271.5 ± 65.0 pg/mL for 10 ng/mL of LPS-stimulated cells, 3353.3 ± 53.2 pg/mL for 100 ng/mL of LPS-stimulated cells, 365.1 ± 5.0 pg/mL for LPS-unstimulated cells co-incubated with pioglitazone, 2087.4 ± 250.0 pg/mL for 1 ng/mL of LPS-stimulated cells co-incubated with pioglitazone, 2181.5 ± 16.0 pg/mL for 10 ng/mL of LPS-stimulated cells co-incubated with pioglitazone, and 2331.9 ± 11.8 pg/mL for 100 ng/mL of LPS-stimulated cells co-incubated with pioglitazone, N = 3 for all groups). *p < 0.005 and **p < 0.0001, compared with the cells stimulated with the same concentration of LPS in the absence of pioglitazone.