Fig. 6

Fibronectin aggregates, but not plasma fibronectin, induce arginase-1 expression by bone marrow-derived macrophages. Bone marrow-derived macrophages (BMDMs, a–c) were left unstimulated (ctrl), cultured on plasma fibronectin (pFn) or fibronectin aggregates (aFn), or treated with interferon-γ (IFNγ) or interleukin-4 (IL-4). Then, the expression of arginase-1 (a, b) and activity (c), indicative for alternative polarization, were analyzed as described in materials and methods. Note that aFn, but not pFn, increased arginase-1 expression (a, b, n = 4–5), along with an increased arginase activity (c, n = 3). Bars represent mean values of each condition relative to control cells (set at 1 for each independent experiment, horizontal line). Error bars show the standard error of the mean. Statistical analyses were performed using the one-sample t-test when compared to control (not significant). A student t test was performed to compare pFn with aFn (# p < 0.05)