大剂量地塞米松对免疫性血小板减少性紫癜患者浆细胞样树突状细胞功能及Toll样受体9 mRNA表达的影响

本研究探讨大剂量地塞米松对免疫性血小板减少性紫癜(ITP)患者外周血浆细胞样树突状细胞(pDC)功能及Toll样受体9(TLR9)表达的影响。15例初诊的ITP患者给予地塞米松40 mg/d,连用4 d,采用免疫磁珠分离法体外分离15例正常对照及13例治疗有效患者治疗前后外周血中pDC;用CpG-ODN 2216刺激外周血pDC并与之共培养24 h,采用ELISA方法检测上清中IFN-α、IL-6、TNF-α的含量;用实时定量聚合酶链反应(RT-PCR)检测pDC的TLR9 mRNA表达量。结果表明,①治疗前pDC产生IFN-α、IL-6、TNF-α水平〔(960.83±164.65)pg/ml,(156.15±39.89)pg/ml,(137.31±35.44)pg/ml)〕明显高于正常对照组〔(616.67±105.98)pg/ml,(89.13±21.48)pg/ml,(88.53±25.81)pg/ml,P<0.05〕;治疗后pDC产生IFN-α、IL-6、TNF-α水平分别降至(678.46±128.88)pg/ml,(97.77±26.31)pg/ml,(103.08±26.42)pg/ml,与治疗前比较差异有统计学意(P<0.05),与正常对照组相比差异无统计学意义(P>0.05);②治疗前pDC的TLR9 mRNA的表达水平高于正常对照组(P<0.05);治疗后pDC的TLR9 mRNA的表达水平低于治疗前(P<0.05),与正常对照组比较差异无统计学显著性(P>0.05)。结论:pDC分泌的细胞因子及其表达的TLR9在ITP发病中起重要作用;地塞米松可能通过下调TLR9的表达,抑制pDC分泌细胞因子的功能,而对ITP起到治疗作用。

Effect of high dose dexamethasone on function and TLR-9 mRNA expression of plasmacytoid dendritic cells in patients with immune thrombocytopenic purpura

This study was purposed to investigate the effect of high-dose dexamethasone (DXM) on function and Toll like receptor 9 (TLR-9) expression of plasmacytoid dendritic cells (pDC) in peripheral blood of patients with immune thrombocytopenic purpura (ITP). 15 newly diagnosed patients with ITP received high dose DXM at single daily doses of 40 mg for 4 consecutive days. The peripheral blood plasmacytoid dendritic cells from 13 remission patients and 15 normal controls were separated by immunomagnetic beads and then induced by CpG-OND2216. 24 h later, the levels of IFN-α, IL-6 and TNF-α in the supernatant were detected by enzyme linked immunosorbent assay (ELISA). The expression of TLR9 mRNA of pDC was detected by real-time quantitative PCR. The results indicated that the levels of IFN-α, IL-6 and TNF-α produced by pDC in ITP patients were significantly higher than those in normal controls (P < 0.05). After high dose DXM treatment, the levels of IFN-α, IL-6 and TNF-α decreased without significant difference compared with normal controls (P > 0.05). The expression of TLR9 mRNA in pDC of untreated patients was significantly higher than that in control group (P < 0.05), and significantly reduced after treatment without difference from that in control group (P > 0.05). It is concluded that pDC may play an important role in ITP by their TLR9 and secreted cytokines; dexamethasone may down regulate the expression of TLR9, inhibit pDC function, and thus play a therapeutic role.