Aggregates of α-synuclein (α-Syn) are the major component of the Lewy bodies associated with Parkinson's disease. Recently, naturally occurring autoantibodies against α-synuclein (α-Syn-nAbs) were detected. Herein we have isolated and further characterized such α-Syn-nAbs. Using an affinity column coated with α-Syn, we have isolated α-Syn-nAbs from a commercially available intravenous Immunoglobulin (IVIg) preparation. A methodological approach based on ELISA, Western blotting and immunoprecipitation as well as surface plasmon resonance, was used to determine binding capacity to α-Syn. The epitope was determined via peptide array membrane and the functionality was tested in vitro using a toxicity and a fibrillation assay. The autoantibodies display strong binding capacity to α-Syn as demonstrated by ELISA, immunoprecipitation and Western blotting analysis. The binding affinities of the purified autoantibodies were analyzed in detail by surface plasmon resonance (Biacore). The epitope on α-Syn that is recognized by the α-Syn nAbs was fully determined. A sequence within the non-amyloid component (NAC)-Region of α-Syn is crucial for the binding of α-Syn-nAbs to α-Syn. Furthermore, the α-Syn-nAbs had an inhibitory effect on α-Syn fibril formation and were also able to specifically reverse the toxicity of α-Syn oligomers species in human neuroblastoma (SH-SY5Y) cells. Our results emphasize the possible importance of naturally occurring autoantibodies for the pathogenesis of Parkinson's disease. Since autoantibodies against α-Syn are detectable in human serum and cerebrospinal fluid and interfere with pathological events associated with α-Syn, they may provide a candidate for the treatment of Parkinson's disease.

Background and objectivesAdult-onset immune-mediated inflammatory disease (IMID) increases the risk of several cancers. However, data on pediatric-onset IMID (pIMID) remains scarce. We estimated the long-term cancer risk in pIMID and the association between medical treatment and specific cancers. MethodsWe used the nationwide Danish health registers to identify pIMID patients diagnosed from Jan 1, 1980 to Dec 31, 2018. Patients were matched with ten reference individuals based on age, sex, and residence. The primary exposure was pIMID, including autoimmune hepatitis, primary sclerosing cholangitis, Crohn's disease, ulcerative colitis, juvenile idiopathic arthritis, systemic lupus erythematosus, vasculitis, and connective tissue disease. Secondary exposures were immunomodulators and tumor necrosis factor-α antagonists (anti-TNFα). The primary outcome was cancer. Estimates are presented as hazard ratios adjusted for family income at diagnosis (AHR). ResultsWe included 12,664 pIMID patients and 109,274 reference individuals. Median follow-up time was 10.6 (interquartile range: 5.4–17.7) years for patients and 10.2 (interquartile range: 5.2–17.3) years for reference individuals. Patients with pIMID had a twofold higher cancer risk (AHR 2.2 [95 % confidence interval (CI): 1.8–2.6]) compared with reference individuals. Thiopurine treatment was associated with a higher risk of lymphoma (AHR 6.1 [95%CI: 2.2–16.8]) and skin cancer (AHR 6.1 [95%CI: 2.4–15.4]). Anti-TNFα treatment was associated with a higher risk of lymphoma (AHR 4.9 [95%CI: 1.1–22.6]). ConclusionsWe found an increased cancer risk in patients with pIMID followed into adulthood. Additionally, thiopurines and anti-TNFα were associated with increased lymphoma and skin cancer risks. This highlights the importance of individualized immunotherapy and cancer surveillance.