Figure 1. Polarizing macrophages to M1 and M2 phenotypes indirectly affects Schwann cells (SC) and axons, in vitro.

(a) Schematic diagram of effect of pro-inflammatory (M1) and anti-inflammatory (M2a and M2c) macrophages on SC and axons represented by red (dark) and green (light) arrows, respectively. M1 and M2 macrophages can modulate proliferation and morphology of axons as well as proliferation and secreting products of SCs. (b) effect of SC migration in CM from macrophages (72 h). Mean ± s.d. n = 4. ***P < 0.001. *P < 0.05 (one-way ANOVA followed by a Tukey's post-hoc) (c) SC proliferation in CM from macrophages. Mean ± s.d. n = 4. ***P < 0.001. **P < 0.01 (one-way ANOVA followed by a Tukey's post-hoc) (72h). Direct effect of the cytokines on the Schwann cell, (d) proliferation and (e) migration. Mean ± s.d. n = 4. **P < 0.01 (Student's t-test). Asterisks denote a significant difference. CM from IL-4 treated macrophages increases the SC migration almost 3 times without affecting the SC proliferation in comparison to the control. Direct addition of cytokines to SC does not have any effect on their migration but decreases their proliferation.