目的·探讨伴有慢性肾衰竭的牙周炎患者的唾液代谢特征，并分析磷代谢物在其中的作用。方法·纳入在上海交通大学医学院附属第九人民医院肾内科及牙周病科求诊的患者45例，分为牙周炎伴慢性肾衰竭（CRF）组（n=15）、单纯牙周炎（CP）组（n=15）和健康对照（HC）组（n=15）。所有研究对象均接受非刺激性唾液样本的采集和牙周临床检查，记录牙周临床指标以及CRF组患者肾功能指标。采用液相色谱-串联质谱（liquid chromatography-tandem mass spectrometry，LC-MS/MS）技术对唾液样本行非靶向代谢组学检测，通过主成分分析（principal component analysis，PCA）探究组间差异，筛选差异代谢物。通过京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes，KEGG）数据库对显著差异代谢物进行代谢通路富集分析。选取一个主要差异代谢物，通过体外实验验证该差异代谢物对小鼠胚胎前体成骨细胞MC3T3-E1成骨分化的影响。结果·CRF组的探诊深度、临床附着丧失、牙菌斑指数均显著高于CP组（均P<0.05）。CRF组的尿素（r=0.41）和肌酐水平（r=0.61）与探诊深度均呈正相关，肌酐水平与临床附着丧失（r=0.53）也呈正相关，估算肾小球滤过率（estimated glomerular filtration，eGFR）与探诊深度（r=-0.69）和临床附着丧失（r=-0.56）均呈负相关。PCA结果显示，3组代谢物谱存在显著差异，其中磷酸在3组间差异明显。KEGG分析结果显示，富集的代谢物主要涉及蛋白质消化与吸收、神经活性配体-受体相互作用、鞘脂代谢、坏死性凋亡、癌症中的胆碱代谢、卵巢类固醇生成、鞘脂信号通路与矿物质吸收。体外实验证实，4 mmol/L磷酸盐离子能降低细胞Runt相关转录因子2（Runt-related transcription factor 2，Runx2）、碱性磷酸酶（alkaline phosphatase，Alp）和骨钙素（osteocalcin，Ocn）的mRNA及蛋白表达（均P<0.05），从而抑制MC3T3-E1细胞成骨分化。结论·伴慢性肾衰竭的牙周炎患者牙周组织破坏较单纯牙周炎患者更严重；唾液中磷浓度上调可能是慢性肾脏病加重牙周组织破坏的机制之一；过高的磷浓度可抑制成骨分化。

Objective ·To investigate the salivary metabolic characteristics of periodontitis patients with chronic renal failure (CRF) and analyze the role of phosphorus metabolites in this pathological process. Methods ·A total of 45 patients treated at the Department of Nephrology and the Department of Periodontology, Shanghai Ninth People′s Hospital, Shanghai Jiao Tong University School of Medicine were enrolled, including 15 patients with both periodontitis and CRF in the CRF group, 15 with only periodontitis in the periodontitis (CP) group, and 15 in the healthy control (HC) group. All participants underwent unstimulated saliva collection and periodontal clinical examination. Periodontal clinical parameters were recorded, and renal function indicators of patients in the CRF group were documented. Untargeted metabolomic analysis of saliva samples was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Principal component analysis (PCA) was used to analyze inter-group differences and screen differential metabolites. Significantly differential metabolites were further analyzed for pathway enrichment using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. One major differential metabolite was selected for in vitro experiments to verify its effect on osteogenic differentiation of mouse embryonic preosteoblasts MC3T3-E1. Results ·Probing depth (PD), clinical attachment loss (CAL), and plaque index (PI) in the CRF group were significantly higher than those in the CP group (all P<0.05). In the CRF group, urea level (r=0.41) and creatinine level (r=0.61) were positively correlated with PD, and creatinine level was also positively correlated with CAL (r=0.53). Estimated glomerular filtration rate (eGFR) was negatively correlated with PD (r=-0.69) and CAL (r=-0.56), respectively. PCA results showed significant differences in metabolite profiles among the three groups, with phosphoric acid presenting remarkable differences. KEGG analysis revealed that the enriched differential metabolites were mainly involved in protein digestion and absorption, neuroactive ligand-receptor interaction, sphingolipid metabolism, necroptosis, choline metabolism in cancer, ovarian steroidogenesis, sphingolipid signaling, and mineral absorption. In vitro experiments confirmed that 4 mmol/L phosphate ions downregulated the mRNA and protein expression levels of Runt-related transcription factor 2 (Runx2), alkaline phosphatase (Alp), and osteocalcin (Ocn) in MC3T3-E1 cells (all P<0.05), thereby inhibiting osteogenic differentiation. Conclusion ·Periodontal tissue destruction is more severe in periodontitis patients complicated with CRF than those without CRF. Upregulated salivary phosphorus concentration may be one of the mechanisms by which chronic kidney disease aggravates periodontal tissue destruction. Excessively high phosphorus concentration can inhibit osteogenic differentiation.