IL17A and neurodegenerative disease: By using patient-specific, iPSC-derived MN cell cultures, devoid of glial and microglial cells and co-cultured with patient-derived Th17 cells, we: (i) provide clear evidence of a direct, deleterious effect of Th17 cells and IL17A on human MNs; (ii) show that MNs express both IL17RA and IL17 RC; and (iii) most importantly, that these effects could be rescued by IL17 neutralization or anti-IL17RA treatment, thus offering novel and exciting drug targets for (motor) neurodegenerative diseases.