| Abstract:Objective:To study the expression of vitamin D receptor (VDR),25-hydroxyvitamin D-24-hydroxylase(CYP24A1),25-hydroxy-vitamin D-1α-hydroxylase(CYP27B1) mRNA in peripheral blood monocytes of patients with Ankylosing Spondylitis (AS), the serum levels of 25-hydroxyvitamin D3(25-D/25-(OH)D3),1,25-Dihydroxy vitamin D3(1,25-D/1,25-(OH)2D3) in AS patients and their relation between the disease activity [erythrocyte sedimentation rate(ESR), C-reactive protein(CRP), Bath Ankylosing Spondylitis Disease Activity Index(BASDAI)], so as to investigate the pathogenesis of AS and to provide the theoretical basis of new therapeutic targets. Methods: Twenty-six patients with AS and 13 age-and sex-matched healthy control were included in the study. Ficoll density gradient centrifugation method was used to segregate peripheral blood mononuclear cells, and then the monocytes were isolated by using its adherent growth characteristics. Total RNA was extracted by Trizol and then reverse transcripted into cDNA. The VDR, CYP24A1, CYP27B1 mRNA expression in the peripheral blood monocytes were examined by real time fluorescent quantitative reverse transcriptase polymerase chain reaction(real-time qRT-PCR) in the two groups.β-actin was used as an endogenous reference. Expression level of VDR, CYP24A1, CYP27B1 mRNA were calculated using the 2-ΔΔCT method. The serum levels of 25-D and 1,25-D in AS patients and healthy control were measured by enzyme linked immuno-sorbent assay(ELISA). The relation between relative expression of VDR mRNA, serum levels of 25-D,1,25-D and the disease activity [erythrocyte sedimentation rate (ESR), C-reactive protein(CRP), Bath Ankylosing Spondylitis Disease Activity Index(BASDAI)] were evaluated by spearman’s rank correlation analysis. Results:1. The expression of VDR mRNA was significantly higher than that in the control group(P<0.01). The expression of CYP24A1 and CYP27B1 mRNA were lower than the control, but the difference does not reach statistically significant(P>0.05).2. There is no correlation between relative expression of VDR mRNA and disease activity (BASDAI, ESR, CRP)(P>0.05).3. The concentration of 25-D in AS group(5.27±2.57 ng/ml) was significantly lower than those in healthy control(14.73±3.52 ng/ml)(P<0.01). The concentration of 1,25-D in AS group(12.82±5.99 pg/ml) was also significantly lower than those in healthy control group(32.58±18.46 pg/ml)(P<0.01).4. In AS group, the negative correlation between the concentration of 1,25-D and BASDAI(r=-0.481, P<0.05),ESR (r=-0.535,P<0.01),CRP(r=-0.674, P<0.01) were found statisticly significant. The negative correlation between serum 25-D level and BASDAI, ESR, CRP levels did not reach a statistically significant level in patients with AS(P>0.05). Conclusion:1. VDR, CYP24A1, CYP27B1 mRNA have been found in peripheral blood monocytes of AS patients.2. The up-regulation of VDR mRNA in peripheral blood monocytes of AS patients may enhance the body’s innate immune response.3. Increased expression of VDR mRNA has no correlation with the disease activity of AS, but may play a role in the pathogenesis of AS. 4. There is correlation between serum 25-D,1,25-D levels and disease activity of AS, so the concentration of 25-D,1,25-D may be one of marker for the disease activity of AS.5. VDR activation may be related to its automatic adjustment function, but not dependent on the 1,25-D level, therefore, the VDR activation may be have no related to the role of 1,25-D.6. In AS patients, abnormal activation of VDR or Vitamin D deficiency may inhibit the expression of CYP27B1, and then reduce the 1,25-D synthesis.7. CYP24A1 may play a role in the maintenance of dynamic equilibrium of 25-D and 1,25-D in patients with AS.8. Increased expression of VDR mRNA and decreased concentration of serum 25-D,1,25-D levels may be involved in the pathogenesis of AS. |
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