Increased plasma lipoprotein lipase activity in males with autism spectrum disorder

Background: Autism spectrum disorder (ASD) is a neurodevelopmental disorder with complex genetics, characterized by impaired social communication and repetitive behaviors and interests. The involvement of lipid metabolism in ASD pathophysiology has been demonstrated in previous studies; however, the molecular mechanisms of abnormal lipid metabolism are not fully understood. A mutation in Lipoprotein lipase (LPL), which has central roles in lipid metabolism, has been identified in patients with ASD. We have reported that Lpl is downregulated in ASD model mice. Therefore, we explored the role of LPL in lipid metabolism in ASD patients. Methods: We quantified LPL amount, LPL activity, and glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) amount in the plasma of ASD male subjects (n = 28) compared with typical development (TD) controls (n = 28), using enzyme-linked immunosorbent assay for LPL amount and fluorometric assays for LPL activity. We examined the correlations of plasma LPL with GPIHBP1 and clinical characteristic scores from the Autism Diagnostic Interview-Revised (ADI-R). Results: There was higher LPL activity, but not LPL amount, in the plasma of ASD subjects compared with controls. Receiver operating characteristics analysis also demonstrated that pure LPL activity (LPL activity/LPL amount) is a useful indicator to distinguish ASD from TD controls. There were no correlations between plasma LPL and ADI-R scores; however, LPL activity was negatively correlated with GPIHBP1 levels in the plasma of ASD subjects. Conclusions: Our results demonstrate increased activity of plasma LPL, regulated by GPIHBP1, in ASD, providing novel insights into the lipid metabolism associated with ASD pathophysiology.