Reduced levels of IgM autoantibodies against N-truncated pyroglutamate Aβ in plasma of patients with Alzheimer's disease

Abstract: In the present work, we investigated the level of IgM autoantibodies directed against different Aβ epitopes as potential diagnostic biomarker for Alzheimer''s disease (AD). Anti-Aβ autoantibody levels were measured in 75 plasma samples from patients with AD, individuals with mild cognitive impairment (MCI), and healthy age- and sex-matched controls (HC). To validate the presence of anti-Aβ IgMs, pooled plasma samples were subjected to gel-filtration analysis. The mean level of pGluAβ-IgM (N-terminal truncated starting at position three with pyroglutamate) was significantly decreased in AD patients as compared to HC. In the group of MCI patients there was a significant positive correlation between pGluAβ-IgM and cognitive decline analyzed by MMSE (rho=0.58, d.f.=13, p =0.022). These observations indicate that the level of IgM autoantibodies against pGluAβ is a promising plasma biomarker for AD and correlates with the cognitive status of individuals at risk to develop AD. [Copyright &y& Elsevier]