Propagation of pathologic α-synuclein from kidney to brain may contribute to Parkinson’s disease

The pathogenesis of Lewy body diseases (LBDs), including Parkinson’s disease (PD), involves α-synuclein (α-Syn) aggregation that originates in peripheral organs and spreads to the brain. PD incidence is increased in individuals with chronic renal failure, but the underlying mechanisms remain unknown. Here we observed α-Syn deposits in the kidneys of patients with LBDs and in the kidney and central nervous system of individuals with end-stage renal disease without documented LBDs. In male mice, we found that the kidney removes α-Syn from the blood, which is reduced in renal failure, causing α-Syn deposition in the kidney and subsequent spread into the brain. Intrarenal injection of α-Syn fibrils induces the propagation of α-Syn pathology from the kidney to the brain, which is blocked by renal denervation. Deletion of α-Syn in blood cells alleviates pathology in α-Syn A53T transgenic mice. Thus, the kidney may act as an initiation site for pathogenic α-Syn spread, and compromised renal function may contribute to the onset of LBDs.