Fig. 6.

IFG increases wild-type GCase levels in animals and in humans. (A) Effect of IFG on wild-type mouse GCase. Eight-week-old male C57BL/6 mice were administered IFG ad libitum in drinking water for 4 weeks at the indicated doses. Animals were sacrificed and GCase activity was measured in tissue lysates as previously described using 4-methylumbelliferyl-β-D-glucopyranoside (Sigma-Aldrich).⁷⁶ Dose-dependent and significant increases in GCase activity (*P<0.05 vs. untreated, t-test) were seen in all four disease-relevant tissues. The data presented have been normalized to untreated levels and represent the mean±SEM of 7 mice per group. Baseline tissue GCase activities were 70±4, 80±5, 37±2, and 40±42 nmol 4-methylumbelliferone/mg protein/h, in liver, spleen, lung, and brain, respectively. Animal husbandry and all in vivo experiments in mice were conducted under Institutional Animal Care and Use Committee–approved protocols. (B) Effect of IFG on normal human GCase. IFG was orally administered to healthy human volunteers once daily for 7 days at 25 mg (squares), 75 mg (triangles), or 225 mg (inverted triangles) as indicated. Blood was drawn on days 1 (predose), 3, 5, 7, 9, 14, and 21 for preparation of mononuclear cells. Cell lysates were used to measure GCase activity via 4-methylumbelliferyl-β-D-glucopyranoside hydrolysis. A time- and concentration-dependent increase in cellular GCase levels was observed, which persisted for up to 1 week after IFG withdrawal. Each point on the graph represents the mean±SD from 6 subjects administered IFG, or 2 subjects administered placebo (circles). Institutional review board approval was obtained for all centers involved in the human studies and all subjects gave written informed consent to participate. Color images available online at www.liebertonline.com/adt