Fig. 6

Th1-like cytokines affect NSC arginine metabolism by inducing defective arginase activity within the urea cycle. a NSCs were cultured in complete medium supplemented with U-¹³C6 L-arginine for 2 and 16 h in the absence and in the presence of Th1- or Th2-like cytokines. Metabolic flux analysis was performed by measuring all labelled metabolites derived from arginine by LC/MS [labelled arginine (a) and ornithine (b) herein reported]. c Arginase enzymatic activity in basal NSCs as well as Th1 and Th2 NSCs was detected by arginase activity colorimetric assay kit. d NSC urea levels were detected by colorimetric assay measuring the ability of NSCs to convert arginine into urea in basal condition and under Th1 or Th2 treatment. e Schematic representation of the most significant findings for the metabolic alteration in the NSC arginine metabolism (modified from [59]). *p ≤ 0.05 or **p ≤ 0.01 vs. basal and Th2 NSCs