Hops extract and xanthohumol ameliorate bone loss induced by iron overload via activating Akt/GSK3β/Nrf2 pathway

Abstract

Osteoporosis is closely related to iron metabolism. This study aimed to investigate whether hops extract (HLE) and its active component xanthohumol (XAN) could ameliorate bone loss caused by iron overload, and explored its potential mechanism. Iron overload mice induced by iron dextran (ID) were used in vivo, and were treated with HLE and XAN for 3months. Bone micro-structure and bone morphology parameters were determined by Micro-CT and TRAP staining. Bone metabolism markers and oxidation indexes in serum and bone tissue were evaluated. For in vitro experiment, bone formation indexes were determined. Moreover, the expression of key proteins in protein kinase B (Akt)/glycogen synthetase kinase 3β (GSK3β)/nuclear factor E2-related (Nrf2) pathway was evaluated by Western blotting. HLE and XAN effectively improved the bone micro-structure of the femur in mice, altered bone metabolism biomarkers, and regulated the expression of proteins related to bone metabolism. Additionally, they significantly promoted cell proliferation, runt-related gene 2 (Runx2) expression, and increased ALP activity in ID-induced osteoblasts. Moreover, HLE and XAN markedly inhibited the increase of oxidative stress caused by iron overload in vivo and in vitro. Further studies showed that they significantly up-regulated the expression of p-Akt, p-GSK3β, nuclear-Nrf2, NAD(P)H:quinoneoxidoreductase 1 (NQO1), and heme oxygenase-1 (HO-1) in ID-induced osteoblasts. These findings indicated hops and xanthohumol could ameliorate bone loss induced by iron overload via activating Akt/GSK3β/Nrf2 pathway, which brought up a novel sight for senile osteoporosis therapy.