Sanguineti R, Monacelli F, Parodi A, Furfaro A L, Borghi R, Pacini D, Pronzato M A, Odetti P, Molfetta L, Traverso N
DIMI, University of Genova, Genoa, Italy.
DIMES, University of Genova, Genoa, Italy.
J Biol Regul Homeost Agents. 2016 Jul-Sep;30(3):713-726.
Osteoporosis is a metabolic multifaceted disorder, characterized by insufficient bone strength. It has been recently shown that advanced glycation end products (AGEs) play a role in senile osteoporosis, through bone cell impairment and altered biomechanical properties. Pentosidine (PENT), a wellcharacterized AGE, is also considered a biomarker of bone fracture. Adequate responses to various hormones, such as 1,25-dihydroxyvitamin D, are prerequisites for optimal osteoblasts functioning. Vitamin K is known to enhance in vitro and in vitro vitamin D-induced bone formation. The aim of the study was to assess the effects of Vitamins D and K and PENT on in vitro osteoblast activity, to convey a possible translational clinical message. Ex vivo human osteoblasts cultured, for 3 weeks, with vitamin D and vitamin K were exposed to PENT, a well-known advanced glycoxidation end product for the last 72 hours. Experiments with PENT alone were also carried out. Gene expression of specific markers of bone osteoblast maturation [alkaline phosphatase, ALP; collagen I, COL Iα1; and osteocalcin (bone-Gla-protein) BGP] was measured, together with the receptor activator of nuclear factor kappa-B ligand/osteoproteregin (RANKL/OPG) ratio to assess bone remodeling. Expression of RAGE, a well-characterized receptor of AGEs, was also assessed. PENT+vitamins slightly inhibited ALP secretion while not affecting gene expression, indicating hampered osteoblast functional activity. PENT+vitamins up-regulated collagen gene expression, while protein secretion was unchanged. Intracellular collagen levels were partially decreased, and a significant reduction in BGP gene expression and intracellular protein concentration were both reported after PENT exposure. The RANKL/OPG ratio was increased, favouring bone reabsorption. RAGE gene expression significantly decreased. These results were confirmed by a lower mineralization rate. We provided in vitro evidence that glycoxidation might interfere with the maturation of osteoblasts, leading to morphological modifications, cellular malfunctioning, and inhibition of the calcification process. However, these processes may be all partially counterbalanced by vitamins D and K. Therefore, detrimental AGE accumulation in bone might be attenuated and/or reversed by the presence or supplementation of vitamins D and K.
骨质疏松症是一种多方面的代谢紊乱疾病，其特征是骨强度不足。最近研究表明，晚期糖基化终末产物（AGEs）通过损害骨细胞和改变生物力学特性，在老年性骨质疏松症中发挥作用。戊糖苷（PENT）是一种特征明确的AGE，也被认为是骨折的生物标志物。对各种激素（如1,25 - 二羟基维生素D）的充分反应是成骨细胞最佳功能的先决条件。已知维生素K可增强体内外维生素D诱导的骨形成。本研究的目的是评估维生素D、维生素K和PENT对体外成骨细胞活性的影响，以传达可能的转化临床信息。将体外培养3周的人成骨细胞与维生素D和维生素K一起培养，并在最后72小时暴露于PENT（一种著名的晚期糖基化终末产物）。也进行了单独使用PENT的实验。测量了骨成骨细胞成熟的特定标志物[碱性磷酸酶，ALP；I型胶原蛋白，COL Iα1；和骨钙素（骨γ-羧基谷氨酸蛋白）BGP]的基因表达，以及核因子κB受体活化因子配体/骨保护素（RANKL/OPG）比值以评估骨重塑。还评估了AGEs的特征明确的受体RAGE的表达。PENT + 维生素略微抑制ALP分泌，同时不影响基因表达，表明成骨细胞功能活性受到阻碍。PENT + 维生素上调胶原蛋白基因表达，而蛋白质分泌未改变。细胞内胶原蛋白水平部分降低，并且在暴露于PENT后报告BGP基因表达和细胞内蛋白质浓度均显著降低。RANKL/OPG比值增加，有利于骨吸收。RAGE基因表达显著降低。较低的矿化率证实了这些结果。我们提供了体外证据表明糖基化可能干扰成骨细胞的成熟，导致形态改变、细胞功能失调和钙化过程的抑制。然而，这些过程可能都被维生素D和K部分抵消。因此，维生素D和K的存在或补充可能会减轻和/或逆转骨骼中有害的AGE积累。
