Figure 6: Tolcapone is orally available and stabilizes TTR in humans and in transgenic mice expressing the amyloidogenic human V30M-TTR variant.
(a) T4 competition was assessed by gel electrophoresis of plasma samples from the transgenic mice expressing human V30M-TTR, before and after oral administration of tolcapone (t=0 and t=end, respectively). Plasma samples were treated with radiolabelled T4 and subjected to native PAGE. The fraction of radiolabelled T4 bound to the band corresponding to TTR is represented. Error bars indicate s.e.m. (n=4). (b) TTR tetramer stability in the plasma of control and tolcapone-treated transgenic mice was assessed by IEF under semi-denaturing conditions62. The ratio between the TTR tetramers and the rest of the TTR species in the IEF gels was calculated for controls and tolcapone-treated mice. The data are expressed as fold increase of the ratio TTR tetramer/total TTR with respect to samples from vehicle-treated animals. ***P<0.001 and **P<0.01 (Student’s t-test). Error bars indicate s.e.m. (n=3). (c) Tetrameric TTR stabilization in plasma from humans treated with an oral dose of 200 or 400 mg of tolcapone (subjects HV1 and HV2, respectively). TTR stabilization was quantified by immunoturbidity after urea denaturation with subsequent crosslinking with glutaraldehyde as detailed in the experimental section. Basal, indicates plasma obtained before tolcapone administration. White bars correspond to plasma samples crosslinked 0 h after urea addition, black bars correspond to plasma samples crosslinked after 48 h of urea denaturation. Bars correspond to average TTR tetramer concentration of three independent determinations, error bars represent standard deviation (n=3).
