Fig. 6: CTSL promotes eosinophil activation by enhancing arginine metabolism via ARG1.

A, B, D–G Eosinophils were isolated from the peripheral blood of Il5 Tg mice and treated with or without IL33 (20 ng/ml) and 50 µM SID26681509 for 8 h. A ELISA analysis (n = 3 biological replicates) of culture supernatants from eosinophils with or without ARG1 overexpression for IL4 and IL13. B ELISA analysis (n = 3 biological replicates) of culture supernatants from eosinophils in the presence or absence of ARG1 protein (2 µg/ml) and 20 µM nor-NOHA for IL4 and IL13. C Eosinophils were isolated from the peripheral blood of control and Ctsl eoΔ Il5 Tg mice. ELISA analysis (n = 3 biological replicates) of culture supernatants from eosinophils in the presence or absence of ARG1 protein. D, E Concentrations of arginine and ornithine in eosinophils (n = 5 biological replicates). F, G ELISA analysis (n = 3 biological replicates) of culture supernatants from eosinophils in the presence or absence of ornithine (5 mM). Data presented are representative of three independent experiments and shown as mean ± SEM. Statistical analyses were calculated using two-way ANOVA with Sidak’s multiple comparisons test.