The Corelated Research Of Chlamydia Pneumoniae Infection And Ankylosing Spondylitis

Objective: To investigate the correlation between recent Chlamydia pneumoniae(Cpn) infection and the onset of ankylosing spondylitis(AS),as well as the clinical value of clarithromycin in the treatment of ankylosing spondylitis.Methods: Clinical data and Peripheral blood of AS patients and normal controls (NC) were enrolled in this study. Chlamydia pneumoniae infection was diagnosised by ELISA for the specific antibodies IgG,IgM,IgA and nest-PCR for the 53kDa outer membrane protein genes of chlamydia pneumoniae.On the other hand,fifty-eight ankylosing spondylitis (AS) patients with active disease were enrolled in the third section of this study. Among them, thirty-eight AS patients (treatment group)received clarithromycin treatment at a dose of 0.5g twice a day for a period of 4-8 weeks, another twenty patients receiving sulfasalazine treatment served as control(control group).>50% decline in ESR , CRP and BASDAI or normalization in ESR and CRP level were considered effective.Results:1 Both AS patients and normal controls had high prevelence of CpIgG antibody (88.8%vs 91.8%) while AS patients had a significant higher positive frequency of CpIgM and CpIgA, compared with normal controls(51.9% vs 31.5%,χ~2=63.61, P=0.010 for CpIgA; 79.7% vs 20.5%,χ~2=44.031, P<0.0001 for CpIgM). Individuals with CpIgM antibody is at high risk for onset of AS (OR=17.07, 95%CI 7.38-39.47), while CpIgA antibody is at less risk (OR=3.05, 95%CI =1.31-7.15).2 Of three specific antibodies, only CpIgM antibody contributed significantly to more patients with active disease including elevated ESR (χ~2=2.56,P=0.021), elevated CRP(χ~2=7.28,P=0.007) and high BASDAI(χ~2=6.79,P=0.009). In addition, AS patients with specific CpIgM antibody also had significant elevated level of serum ESR, CRP and higher BASDAI compared with negative CpIgM cases (ESR, 38.9±28.9 VS 21.4±20.7 mm/h P=0.023; CRP,32.6±38.3 VS 11.00±13.3,mg/L P<0.001; BASDAI 4.67±1.94 VS 2.93±1.16 P<0.001). 3 The positive rate of Cpn infection diagnosised by nPCR in the thirty AS patients was significantly higher than that in the thirty normal persons (36.7% vs 10.0%,χ~2=5.96, P=0.015). In addition, AS patients with positive nPCR results also had significant elevated level of serum ESR, CRP and higher BASDAI compared with negative patients ( BASDAI , 5.67(1.6)vs4.23(1.60),Z=-2.42 , P=0.014;CRP ,29.2(16.9)vs10.20(7.85),Z=-3.12,P<0.01;ESR,33.00(39.0)vs23.00(13.00),Z=-2.67 ,P<0.01).4 Patients receiving clarithromycin treatment presented a maximum decrease at 6-8weeks in disease activity parameters, significant lower than that of controls(BASDAI, 4.20(1.00) vs 4.70(1.38), Z=-2.26,P=0.02;CRP, 9.95(11.24) vs 16.45(25.21),Z=-2.30,P=0.02;ESR, 23.00(16.00)vs 26.00(23.00), Z=-2.09,P=0.03). In another way, >50% disease improvement rate also peaked at week 6-8(BASDAI:44.74%, CRP:68.42%, ESR:65.79%) and bottomed at month six(BASDAI:25%, CRP:33.33%, ESR:33.33%).Conclusion:1 Our study first discovered that recent chlamydia pneumoniae infection (acute infection/Chronic persistent infection)is highly associated with the onset of ankylosing spondylitis.Cpn IgM antibody is related with, but not fully responsible for, the active disease.Acute infection of Cpn can elevate disease activity of AS.2 We have also proposed hypothesis about pathogenesis of AS triggered by Cpn:Chlamydial pneumoniae antigenic components (such as chlamydial LPS and cHSP60) can raise a number of immune cascade and induce the expression and secretion of inflammatory cytokines(such as IL-1,TNF-α) though TLR2-or TLR4-dependent way, which eventually result in onset of active AS.3 The diagnosis of Cpn infection in peripheral blood by PCR also supported the correlation between Cpn infection and AS,but positive rate of Cpn infection in peripheral blood detected by nPCR is less than ELISA.4 Our study also discovered the short-term treatment of Clarithromycin can significantly reduce the disease activity of AS,which would be a new proposal in AS treatment.