Fig 1: IGF-1 downregulates MMP8 and reduces collagenase activity in cultured THP-1 macrophages.A) THP-1 macrophages were differentiated with PMA (100nM, 48 hours), serum starved, and treated with IGF-1 (20, 100 ng/mL for 48 hours). MMP8 levels were measured in the culture supernatant by ELISA. (n = 3−6 wells in two independent experiments). B) THP-1 macrophages were treated with 100ng/mL IGF-1 and/or picropodophyllin (PPP, 50nM) for 48 hours and MMP8 was measured in the culture supernatant by ELISA. (n = 3 wells per group). C) After THP-1 differentiation, cells were treated for 24 hours with 100ng/mL IGF-1, and DQ fluorescent collagen (50 µg/mL) was added to culture. Fluorescence as Arbitrary Units (AU) was measured. (n = 6 wells per group). D) Total MMP activity (Abcam ab112146) in cell lysate were normalized to total protein in THP-1 cells treated with 100ng/mL IGF-1 for 24 hours (n = 4−5 wells per group). E) In independent experiments, Active MMP8/Total MMP8 levels were normalized to total protein in THP-1 cells treated with 100ng/mL IGF-1 for 24 hours and measured via QuickZyme MMP8 Activity Assay in media (n = 3 wells per group). A,B used 1-way ANOVA with a Tukey post hoc test. All other statistical tests are Student 2-tailed t test. *p < 0.05 vs control, **p < 0.01 vs control.