Insulin-Like Growth Factor-I Induces Arginase Activity in Leishmania amazonensis Amastigote-Infected Macrophages through a Cytokine-Independent Mechanism
Figure 1
Effect of IGF-I on the Leishmania amastigote-macrophage interaction. (a) Parasite burden evaluated after 2 and 48 h of culture. (b) Arginase expression analyzed in infected macrophages at 24 h with western blotting using an anti-arginase-I antibody. (c) Arginase activity evaluated in the interaction measuring urea production with and without the arginase inhibitor NOHA. (d) Effect of inhibition by NOHA on the parasite burden in Leishmania amastigote-infected macrophages. (e) Measurement of nitrite production in the culture supernatant by the Griess method. (f) Effect of IGF-I on the arginase activity of Leishmania amastigotes. BALB/c peritoneal macrophages were infected with amastigotes of Leishmania (L.) amazonensis. Amastigotes (ama) or macrophages (mϕ) were prestimulated for 5 min with IGF-I (50 ng/mL) before interaction or the factors were maintained in the culture system (syst) throughout the experiment period. For further details see Material and Methods Section. compared with amastigote-infected macrophage without IGF-I stimulation (ANOVA and Student Newman-Keuls tests). # compared with culture without NOHA (ANOVA and Student Newman-Keuls tests).
