Anti-BGLAP monoclonal antibody, clone FQS4701

Lactoferrin (LF) is an iron-binding glycoprotein that plays an important role in promoting bone formation and inhibiting bone resorption; however, its effects on senile osteoporosis remain unknown. This study aimed to investigate the effects and mechanism of LF intervention using a senile osteoporosis model (SAMP6 mice) and senescent osteoblasts. Micro-CT and hematoxylin and eosin staining demonstrated that the intragastric administration (2 g/kg/day) of LF could improve the bone mass and microstructure of SAMP6 mice. Furthermore, LF treatment improved bone metabolism and increased insulin-like growth factor 1 (Igf1) mRNA expression and activated phosphorylation status of AKT. Using osteoblasts passaged for ten generations as an in vitro senescence model, various markers associated with osteoblast formation and differentiation, as well as related indices of oxidative stress were analyzed. Our results revealed that after multiple generations, osteoblasts entered senescence, in conjunction with increased oxidative stress damage, reduced bone metabolism and enhanced expression of aging-related markers. While inhibiting oxidative stress, LF improved osteoblast proliferation by promoting the expression of osteogenesis markers, including alkaline phosphatase (ALP) activity, Igf1, bone gla protein (Bglap) and osteoprotegerin/receptor activator of nuclear factor-kB ligand (Opg/Rankl) mRNA and delayed senescence by decreasing the level of p16 and p21 expression. RNAI-mediated downregulation of IGF1 attenuated the effect of LF on osteogenesis. Therefore, the findings of the present study indicate that LF may promote osteogenesis via IGF1 signaling, thereby preventing senile osteoporosis.

With the acceleration of aging population in the world, the incidence of age-related bone loss has shown an obvious rising trend. It is of great significance to find effective approaches to relieve senile osteoporosis. Nobiletin is one of the most abundant flavonoids in citrus genus with many important biological properties. Herein, 20-month natural aging mice were used as senile osteoporosis model and were treated with nobiletin by consecutive intraperitoneal injection for 15 days. Micro-CT results showed that nobiletin significantly improved the bone microstructure featured by increased bone volume fraction and decreased trabecular separation. HE staining results indicated that nobiletin increased the number of osteoblasts of trabecular bone surface. Serum osteocalcin (gene Bglap) level was also found to be significantly increased in mice by nobiletin treatment. We then tested the effect of nobiletin in mouse pre-osteoblast (MC3T3-E1 cells) model and found that nobiletin significantly up-regulated Mki67 expression, increased Bglap expression and alkaline phosphatase enzyme activity, and markedly enhanced the alizarin red S staining, suggesting that nobiletin can promote osteoblast proliferation, differentiation and mineralization. Further study of the underlying mechanism showed that nobiletin increased the retinoic acid receptor-related orphan receptor alpha (ROR alpha, gene Rora), down-regulated sclerostin (SOST, gene Sost) and up-regulated osteocalcin, while knocking down of Rora significantly compromised the regulation of nobiletin on Sost and Bglap, indicating that the improving effect of nobiletin on age-related bone loss depends on ROR alpha. To our knowledge this is the first report that nobiletin shows improvement effect on bone loss in natural aging mice and the first report that nobiletin down-regulates Sost through Rora. These results provide a new mechanism of nobiletin in age-related bone loss and a new potential strategy to improve the senile osteoporosis.