mAo cells in culture with MΦ cells contribute to local NO production in response to LPS and LPS/IFNγ. Nitrite production as a measure of NO in culture supernatants of mAo, MΦ, and splenic MΦ cells derived from TLR4-deficient mice (TLR4-MΦ) treated (A) with LPS (100 ng/mL) and (B) with LPS (100 ng/mL) + IFNγ (250 ng/mL) alone and in co-culture. Data are presented as mean ± standard error of the mean and are representative of three experiments each with n = 4. *Significantly different from MΦ cells alone; #significantly different from TLR4-MΦ cells alone. (C) Representative Western blots from a separate experiment showing iNOS expression. Whole lysates were prepared from cultures, and 50 μg was loaded per lane. β-actin was used to control for protein loading. IFNγ, interferon-gamma; iNOS, inducible nitric oxide synthase; LPS, lipopolysaccharide; MΦ, bone marrow-derived macrophage; mAo, mouse aorta-derived mesenchymal progenitor; MSC, mesenchymal stem cell; NO, nitric oxide; TLR4, Toll-like receptor-4; TLR4-MΦ, Toll-like receptor-4-deficient macrophage.