Fig. 6.

Involvement of NF-κB and STAT3 signaling pathways in IEC–adipocyte inflammatory interactions. (a) Mouse IECs were cultured for 2 days in medium from MEF-derived adipocytes (Ad sup) or normal medium (–). Relative MMP-9 mRNA levels were determined by quantitative RT-PCR normalized to GAPDH mRNA levels. The assay was performed in triplicate. Data are presented as mean ± SEM, *P < 0.05 (Student's t-test). “Ad” denotes adipocytes. (b) MEF adipocytes (Day 11) were cultured for 2 days in medium from mouse IECs (mIEC sup) or normal medium (–). Relative MMP-9 mRNA levels were determined by quantitative RT-PCR normalized to 18 s rRNA levels. The assay was performed in triplicate. Data are presented as mean ± SEM. (c, d) Mouse IECs (c) and MEF adipocytes (d) were co-cultured with or without 10 μM CAPE (NF-κB inhibitor) or 10 μM Gal (STAT3 inhibitor) for 2 days. Each culture was then harvested and relative MMP-9 mRNA levels were determined by quantitative RT-PCR normalized to GAPDH mRNA (c) or 18 s rRNA (d) levels. The assay was performed in triplicate. Data are presented as mean ± SEM, *P < 0.05 (one-way ANOVA). (e, f) Mouse IECs (e) and MEF adipocytes (f) were co-cultured with 1 μg/mL IgG, anti-mouse TNF, or anti-IL-6 antibodies for 2 days. Each culture was then harvested and relative MMP-9 mRNA levels were determined by quantitative RT-PCR normalized to GAPDH mRNA (e) or 18 s rRNA (f) levels. The assay was performed in triplicate. Data are presented as mean ± SEM, *P < 0.05 (one-way ANOVA). (g) Schematic of the putative paracrine loop between IECs and adipocytes inducing a vicious inflammatory cycle. *P < 0.05. All data are representative of two independent experiments.