Therapies, including administration of the granulocyte macrophage-colony stimulating factor (GM-CSF) and the vasoactive intestinal peptide (VIP), avert the inflammatory role of effector T cells (Teff) by inducing T regulatory cells (Tregs), which are severely diminished in PD patients (Saunders et al., 2012). Here, CSF2 is linked to Parkinson disease.