Efficacy of bezafibrate on fibroblasts of glutaric acidemia type II patients evaluated using an in vitro probe acylcarnitine assay

Introduction: We evaluated the effects of bezafibrate (BEZ) on beta-oxidation in fibroblasts obtained from patients with glutaric acidemia type II (GA2) of various clinical severities using an in vitro probe (IVP) assay. Methods: Cultured fibroblasts from 12 patients with GA2, including cases of the neonatal-onset type both with and without congenital anomalies (the prenatal- and neonatal-onset forms, respectively), the infantile-onset, and the myopathic forms, were studied. The IVP assay was performed by measuring acylcarnitines (ACs) in the cell culture medium of fibroblasts incubated with palmitic acid for 96 h in the presence of 0-800 mu M BEZ using tandem mass spectrometry. Results: The IVP assay showed that 100 mu M BEZ markedly reduced the level of palmitoylcarnitine (C16) in the neonatal-onset, infantile-onset, and myopathic forms of GA2, either increasing or maintaining a high level of acetylcarnitine (C2), which serves as an index of energy production via beta-oxidation. In the prenatal-onset form, although a small reduction of C16 was also observed in the presence of 100 mu M BEZ, the level of C2 remained low. At concentrations higher than 100 mu M, BEZ further decreased the level of ACs including C16, but a concentration over 400 mu M decreased the level of C2 in most cases. Discussion: BEZ at 100 mu M was effective for all GA2 phenotypes except for the prenatal-onset form, as a reduction of C16 without deterioration of C2 is considered to indicate improvement of beta-oxidation. The effects of higher doses BEZ could not be estimated by the IVP assay but might be small or nonexistent. (C) 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.