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.
Xin-wei Chen, Ye-hong Li, Meng-jun Zhang, Zhou Chen, Dian-shan Ke, Ying Xue and Jian-ming Hou
Kamran Ullah, Tanzil Ur Rahman, Hai-Tao Pan, Meng-Xi Guo, Xin-Yan Dong, Juan Liu, Lu-Yang Jin, Yi Cheng, Zhang-Hong Ke, Jun Ren, Xian-Hua Lin, Xiao-Xiao Qiu, Ting-Ting Wang, He-Feng Huang and Jian-Zhong Sheng
Previous studies have shown that increasing estradiol concentrations had a toxic effect on the embryo and were deleterious to embryo adhesion. In this study, we evaluated the physiological impact of estradiol concentrations on endometrial cells to reveal that serum estradiol levels probably targeted the endometrium in controlled ovarian hyperstimulation (COH) protocols. An attachment model of human choriocarcinoma (JAr) cell spheroids to receptive-phase endometrial epithelial cells and Ishikawa cells treated with different estradiol (10−9 M or 10−7 M) concentrations was developed. Differentially expressed protein profiling of the Ishikawa cells was performed by proteomic analysis. Estradiol at 10−7 M demonstrated a high attachment rate of JAr spheroids to the endometrial cell monolayers. Using iTRAQ coupled with LC–MS/MS, we identified 45 differentially expressed proteins containing 43 significantly upregulated and 2 downregulated proteins in Ishikawa cells treated with 10−7 M estradiol. Differential expression of C3, plasminogen and kininogen-1 by Western blot confirmed the proteomic results. C3, plasminogen and kininogen-1 localization in human receptive endometrial luminal epithelium highlighted the key proteins as possible targets for endometrial receptivity and interception. Ingenuity pathway analysis of differentially expressed proteins exhibited a variety of signaling pathways, including LXR/RXR activation pathway and acute-phase response signaling and upstream regulators (TNF, IL6, Hmgn3 and miR-140-3p) associated with endometrial receptivity. The observed estrogenic effect on differential proteome dynamics in Ishikawa cells indicates that the human endometrium is the probable target for serum estradiol levels in COH cycles. The findings are also important for future functional studies with the identified proteins that may influence embryo implantation.