Li Ping, Schwarz Edward M, O'Keefe Regis J, Ma Lin, Looney R John, Ritchlin Christopher T, Boyce Brendan F, Xing Lianping
University of Rochester Medical Center, Rochester, New York 14642, USA.
Arthritis Rheum. 2004 Jan;50(1):265-76. doi: 10.1002/art.11419.
To investigate the mechanisms whereby tumor necrosis factor alpha (TNFalpha) increases osteoclastogenesis in vivo.
TNFalpha-transgenic (TNF-Tg) and wild-type mice injected with TNFalpha were studied. In vitro osteoclastogenesis assays, monocyte colony-forming assays, and fluorescence-activated cell sorting were performed using splenocytes, peripheral blood mononuclear cells (PBMCs), and bone marrow cells to quantify and characterize osteoclast precursors (OCPs). Etanercept, a TNFalpha antagonist, was used to block TNFalpha activity in vivo. The effects of TNFalpha on proliferation, apoptosis, and differentiation of OCPs were assessed using 5-bromo-2'-deoxyuridine labeling, annexin V staining, and reverse transcriptase-polymerase chain reaction.
OCP numbers were increased 4-7-fold in PBMCs and spleen, but not in bone marrow of TNF-Tg mice. The OCPs in spleen were in the CD11b(high) population and contained both c-Fms- and c-Fms+ cells. The increased number of OCPs correlated with the initiation of detectable TNFalpha in serum and the onset of inflammatory arthritis in TNF-Tg mice. Etanercept eliminated the increase in peripheral OCPs. TNFalpha did not affect proliferation, survival, or differentiation of CD11b(high) splenocytes in vivo or in vitro, but caused a rapid increase in CD11b+ cells in blood within 4 hours of a single injection and an accumulation of CD11b(high) OCPs in spleen after 3 days of multiple injections.
Systemic TNFalpha induces a marked increase in circulating OCPs that is reversible by anti-TNF therapy and may result from their mobilization from bone marrow. Our findings provide a new mechanism whereby TNFalpha stimulates osteoclastogenesis in patients with inflammatory arthritis, suggesting that CD11b+ PBMCs could be used to evaluate a patient's potential for erosive disease and the efficacy of anti-TNF therapy.
研究肿瘤坏死因子α（TNFα）在体内增加破骨细胞生成的机制。
对注射了TNFα的TNFα转基因（TNF-Tg）小鼠和野生型小鼠进行研究。使用脾细胞、外周血单个核细胞（PBMC）和骨髓细胞进行体外破骨细胞生成试验、单核细胞集落形成试验以及荧光激活细胞分选，以量化和表征破骨细胞前体（OCP）。使用TNFα拮抗剂依那西普在体内阻断TNFα活性。使用5-溴-2'-脱氧尿苷标记、膜联蛋白V染色以及逆转录聚合酶链反应评估TNFα对OCP增殖、凋亡和分化的影响。
TNF-Tg小鼠的PBMC和脾脏中OCP数量增加了4至7倍，但骨髓中未增加。脾脏中的OCP存在于CD11b（高表达）群体中，包含c-Fms-和c-Fms+细胞。OCP数量的增加与TNF-Tg小鼠血清中可检测到的TNFα的起始以及炎性关节炎的发作相关。依那西普消除了外周OCP的增加。TNFα在体内和体外均不影响CD11b（高表达）脾细胞的增殖、存活或分化，但单次注射后4小时内血液中的CD11b+细胞迅速增加，多次注射3天后脾脏中CD11b（高表达）OCP积累。
全身性TNFα诱导循环中OCP显著增加，抗TNF治疗可使其逆转，这可能是由于它们从骨髓中动员所致。我们的研究结果提供了一种新机制，即TNFα刺激炎性关节炎患者的破骨细胞生成，表明CDllb+PBMC可用于评估患者发生侵蚀性疾病的可能性以及抗TNF治疗的疗效。
