Kang Inyoung, Koo Myoungjoo, Jun Jin Hyun, Lee Jaewang
Department of Biomedical Laboratory Science, Eulji University, Seongnam, Republic of Korea.
Clin Exp Reprod Med. 2024 Sep;51(3):236-246. doi: 10.5653/cerm.2023.06744. Epub 2024 Apr 11.
Nicotinamide mononucleotide (NMN) is extensively utilized as an anti-aging agent and possesses anti-inflammatory properties. Lipopolysaccharide (LPS) activates Toll-like receptor 4, a process modulated by intracellular signaling pathways such as the Wnt/β-catenin pathway. This study investigated the impact of NMN on osteogenesis in the presence of LPS.
To elucidate the role of NMN in osteogenesis in the context of Gram-negative bacterial infection after LPS treatment, we cultured a mouse pre-osteoblast cell line (MC3T3-E1) and subsequently incubated it with NMN and/or LPS. We then evaluated osteogenic activity by measuring alkaline phosphatase activity, assessing gene expression and protein levels, and performing Alizarin Red S staining and immunocytochemistry.
MC3T3-E1 cells underwent successful differentiation into osteoblasts following treatment with osteogenic induction medium. LPS diminished features related to osteogenic differentiation, which were subsequently partially reversed by treatment with NMN. The restorative effects of NMN on LPS-exposed MC3T3-E1 cells were further substantiated by elucidating the role of Wnt/β-catenin signaling, as confirmed through immunocytochemistry.
This study showed that infection with Gram-negative bacteria disrupted the osteogenic differentiation of MC3T3-E1 cells. This adverse effect was partially reversed by administering a high-dose of NMN. Drawing on these results, we propose that NMN could serve as a viable therapeutic strategy to preserve bone homeostasis in elderly and immunocompromised patients.
烟酰胺单核苷酸（NMN）被广泛用作抗衰老剂，并具有抗炎特性。脂多糖（LPS）激活Toll样受体4，这一过程由细胞内信号通路如Wnt/β-连环蛋白通路调节。本研究调查了NMN在LPS存在下对成骨作用的影响。
为阐明LPS处理后革兰氏阴性菌感染背景下NMN在成骨中的作用，我们培养了小鼠前成骨细胞系（MC3T3-E1），随后将其与NMN和/或LPS孵育。然后我们通过测量碱性磷酸酶活性、评估基因表达和蛋白质水平以及进行茜素红S染色和免疫细胞化学来评估成骨活性。
用成骨诱导培养基处理后，MC3T3-E1细胞成功分化为成骨细胞。LPS减少了与成骨分化相关的特征，随后用NMN处理部分逆转了这些特征。通过免疫细胞化学证实，NMN对暴露于LPS的MC3T3-E1细胞的修复作用通过阐明Wnt/β-连环蛋白信号的作用得到进一步证实。
本研究表明革兰氏阴性菌感染破坏了MC3T3-E1细胞的成骨分化。通过给予高剂量的NMN，这种不利影响得到了部分逆转。基于这些结果，我们提出NMN可以作为一种可行的治疗策略，以维持老年人和免疫功能低下患者的骨稳态。
