Figure 4

Neuronal outgrowth, Schwann cell (SC) viability, and Matrix metalloproteinases (MMP) activity in Interleukin 17 (IL-17) treated cultures. (A) Neuronal outgrowth was assessed in mouse dorsal root ganglia (DRG) co-cultures after exposure for 21 days to IL-17 at the indicated concentrations. Representative neurofilament (NF)-stained images of the cultures are depicted. (B) Quantification of NF, using densitometry analysis, normalized to background fluorescence and control stimulation. Analysis did not reveal a significant alteration in neuronal outgrowth. (C) SC viability was analyzed after IL-17 stimulation for 7 days at the indicated concentrations. Concentrations between 0.5 and 50 ng/mL did not significantly alter SC viability. Graph for viability and neurofilament analysis shows results of three independent experiments (D, E). MMP activity in IL-17-treated DRG co-culture supernatants was analyzed using gelatine zymography and quantified densitometrically. Representative zymography with the densitometry analysis is depicted. Overall, three independent experiments were performed and analyzed, exhibiting comparable results. AU, arbitrary unit. IL-17 led to a dose-dependent increase in inflammatory MMP-9 activity (E; 92 kDa), whereas the active and the inactive form of MMP-2 (D; MMP-2 inactive: 72 kDa, active: 62 kDa) decreased in activity.