Significance Of Regulation Of Toll-like Receptor 9/myeloid Differentiation Factor 88 Signaling Pathway In Patients With Systemic Lupus Erythematosus

Objective To investigate significance of regulation of TLR9/MyD88 signaling pathway in patients with SLE.Methods The study was performed in 35 patients with SLE, 30 females and 5 males, age range 15～70 yrs, mean age 38±13 yrs which met at least 4 of 11 revised classified criteria of the American College of Rheumatology (ACR) in 1997. Fifteen healthy controls, sex- and age- matched, served as a control group. No patients had taken hydroxychloroquine and infection was excluded. SLE disease activity was assessed by the SLE disease activity index (SLEDAI), and twenty patients with SLEDAI≥10 were considered to have active disease, fifteen patients with SLEDAI<10 were stable disease. Peripheral blood mononuclear cells (PBMC) were isolated and cultured in the presence or absence of 1μmol/L CpG ODN2216 for 24h. The level of TLR9,MyD88 mRNA were investigated with reverse transcription polymerase chain reaction(RT-PCR); The difference of TLR9,MyD88 mRNA expressions were compared among active, stable and control group; And the correlations between the level of TLR9, MyD88 mRNA and immunologic and clinical data were analyzed in patients with SLE. IFN-αin supernatants was detected with ELISA. Besides, PBMCs from 10 patients with SLE were cultured for 2 hours with 1μM CpG ODN2216, and then cultured in the presence or absence of 1μM HCQ for 16h, the differences of TLR9 and MyD88 mRNA expressions were compared.Result The expressions of TLR9 and MyD88 mRNA in patients with SLE were significantly higher than that in normal controls(p<0.01); TLR9 and MyD88 mRNA expressions in active patients were significantly higher than that in stable patients. TLR9 mRNA in patients with SLE had significantly positive correlation with disease activity(r=0.471, p<0.05) and negative correlation with C3 and C4(r=-0.479, r=-0.493, p<0.05). Up-regulation of TLR9 and MyD88 mRNA in patients with SLE were observed in the presence of CpG ODN2216 (p<0.01, p<0.05), especially in active patients; IFN-αin supernatants in active SLE patients was significantly higher than that in stable patients and normal controls (p<0.01). The levels of TLR9 and MyD88 mRNA expression decreased significantly in the presence of HCQ(p<0.001).Conclusion TLR9/MyD88 signaling pathway is strikingly active in patients with SLE. CpG ODN induces upregulation of TLR9 and MyD88 mRNA results in a large amount of interferon-αproduction. HCQ can inhibit activation of TLR9/MyD88 signaling pathway induced by CpG ODN via down-regulating TLR9 and MyD88 mRNA expressions.