Autoantibodies Toward the Angiotensin 2 Type 1 Receptor: A Novel Autoantibody in Alzheimer's Disease.

BACKGROUND

Autoantibodies with agonist function are described in cardiovascular disorders. Since vascular risk factors are associated with an increased risk for Alzheimer's disease (AD), we investigated a potential association between antibodies to the angiotensin 2 type 1 receptor (anti-AT1R) and AD.

OBJECTIVE

The primary objective of this study was to investigate the association between anti-AT1R and AD. The secondary objective was to investigate the association between clinical or biomarker features of AD and anti-AT1R.

METHODS

Samples from patients with mild AD participating in a longitudinal study in Western Norway (n = 92, 65 [71%] females, mean age 74.8 [range 50-89]) and age- and gender-matched healthy controls (n = 102) were included. Cerebrospinal fluid (CSF) AD biomarkers were assessed in a subgroup of patients. Patients were examined annually, including Mini-Mental State Examination. ELISA was used to measure anti-AT1R in serum. Non-parametric tests were used for statistical calculations and a p <  0.05 was considered significant.

RESULTS

AD patients had significantly higher levels of anti-AT1R compared with healthy controls (10.2 U/mL versus 8.1 U/mL, p = 0.04). This difference was found only in patients without hypertension and diabetes. Anti-AT1R levels correlated with CSF total tau (p = 0.03) and phosphorylated tau (p = 0.03) levels, and inversely with blood pressure in AD (Spearman R -0.277, p = 0.008).

DISCUSSION

AD is associated with increased levels of anti-AT1R, and the antibodies correlated with CSF total, and phosphorylated tau levels. Further research is needed to understand the blood pressure response in AD without hypertension and a potential link between tau and anti-AT1R in AD.