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. 2008 Nov 7;18(3):482–496. doi: 10.1093/hmg/ddn376

Figure 5.

Figure 5.

M2 macrophages inhibit muscle cell lysis by M1 macrophages via an arginase-1 dependent mechanism. Cytotoxicity assays showed that M1 and M2 peritoneal macrophage cocultures resulted in a 17% reduction in myotube lysis when compared with M1 only cultures (A). In contrast, coculturing M1 macrophages with non-stimulated peritoneal macrophages resulted in a 17% increase in myotube lysis when compared with M1 only cultures (A). Measurements of nitrite showed that the reduction of muscle cell lysis observed in M1:M2 cocultures was attributed to reduced nitrite levels (B) and occurred without a reduction in iNOS protein (C). Cytotoxicity assays performed in the presence of BEC showed that inhibition of arginase activity resulted in a dose-dependent increase in nitrite formation (D) and muscle cell lysis (E) in M1:M2 cocultures compared with non-treated macrophage:M2 cocultures. *, P < 0.05 when compared with M1 only cultures. ♦, P < 0.01 when compared with non-treated macrophage:M1 cocultures. §, P < 0.05 when compared with non-treated M1:non-coculture. #, P < 0.01 when compared with same coculture conditions not treated with BEC. £, P < 0.01 when compared with same coculture condition treated with 1 µM BEC. τ, P < 0.05 when compared with same coculture condition treated with 10 µM BEC. Representative histograms of 2–5 independent experiments are shown.