title: Epitope Mapping of Antibodies to Alpha-Synuclein in LRRK2 Mutation Carriers, Idiopathic Parkinson Disease Patients, and Healthy Controls.
abstract: Alpha-synuclein (Snca) plays a major role in Parkinson disease (PD). Circulating anti-Snca antibodies has been described in PD patients and healthy controls, but they have been poorly characterized. This study was designed to assess the prevalence of anti-Snca reactivity in human subjects carrying the LRRK2 mutation, idiopathic PD (iPD) patients, and healthy controls and to map the epitopes of the anti-Snca antibodies. Antibodies to Snca were detected by ELISA and immunoblotting using purified recombinant Snca in plasma from individuals carrying LRRK2 mutations (104), iPD patients (59), and healthy controls (83). Epitopes of antibodies were mapped using recombinant protein constructs comprising different regions of Snca. Clear positive anti-Snca reactivity showed no correlation with age, sex, years of evolution, or the disability scores for PD patients and anti-Snca reactivity was not prevalent in human patients with other neurological or autoimmune diseases. Thirteen of the positive individuals were carriers of LRRK2 mutations either non-manifesting (8 out 49 screened) or manifesting (5 positive out 55), three positive (out of 59) were iPD patients, and five positive (out of 83) were healthy controls. Epitope mapping showed that antibodies against the N-terminal (a.a. 1-60) or C-terminal (a.a. 109-140) regions of Snca predominate in LRRK2 mutation carriers and iPD patients, being N122 a critical amino acid for recognition by the anti-C-terminal directed antibodies. Anti-Snca circulating antibodies seem to cluster within families carrying the LRRK2 mutation indicating possible genetic or common environmental factors in the generation of anti-Snca antibodies. These results suggest that case-controls' studies are insufficient and further studies in family cohorts of patients and healthy controls should be undertaken, to progress in the understanding of the possible relationship of anti-Snca antibodies and PD pathology.
authors: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols", UAM-CSIC, Facultad de Medicina, Universidad Autónoma de Madrid , Madrid , Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) , Madrid , Spain.
authors: Beatriz
authors: B
authors: Alvarez-Castelao
authors: Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) , Madrid , Spain ; Servicio de Neurología, Hospital Donostia , San Sebastián , Spain ; Area de Neurociencias, Instituto Biodonostia , San Sebastián , Spain.
authors: Ana
authors: A
authors: Gorostidi
authors: Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) , Madrid , Spain ; Servicio de Neurología, Hospital Donostia , San Sebastián , Spain ; Area de Neurociencias, Instituto Biodonostia , San Sebastián , Spain.
authors: Javier
authors: J
authors: Ruíz-Martínez
authors: Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) , Madrid , Spain ; Servicio de Neurología, Hospital Donostia , San Sebastián , Spain ; Area de Neurociencias, Instituto Biodonostia , San Sebastián , Spain ; Departamento de Neurociencias, Universidad del País Vasco-Euskal Herriko Unibertsitatea , San Sebastián , Spain.
authors: Adolfo
authors: A
authors: López de Munain
authors: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols", UAM-CSIC, Facultad de Medicina, Universidad Autónoma de Madrid , Madrid , Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) , Madrid , Spain.
authors: José G
authors: JG
authors: Castaño
keywords: ELISA; LRRK2 mutation; Parkinson disease; alpha-synuclein; epitope mapping; human antibodies; immunoblot