| Objective: Ankylosing spondylitis(AS) was a kind of agnogenic chronicity systemic autoimmune disease. Besides the joints and system involvement, low bone mineral density (BMD) or osteoporosis (OP) could appear in AS. At present,the mechanism and bone metabolism of OP in AS were not yet elucidating completely. Matrix metalloproteinases(MMPs) were related to the happen of bone metabolic disturbance and osteoporosis. The aim of this study was to investigate the pathogenesy of AS and the secondary OP of AS through the expression of serum levels of matrix metalloproteinase -2,-3,-9 in ankylosing spondylitis and their relationship with bone metabolic markers and BMD in different sites, providing evidence for the scheme′s alternation of the prevention and treatment and improving the prognosis of AS patients.Methods: Thirty AS patients and twenty healthy controls were chosen. All the patients included were in accord with the New York criteria of AS, who were not ever continuously treated with disease modifying antirheumatic drugs(DMARDs) and biologic agent. The BMD of lumbar, femoral neck, and greater trochanter of AS patients were measured through dual-energy X-ray absorptiometry(DXA).Erythrocyte sedimentation rate(ESR), c-reactive protein (CRP), calcium(Ca), phosphrus(P), alkaline phosphatase(ALKP), human leucocyte antigen(HLA-B27), parathyroid hormone(PTH) and clinical symptoms of AS patients were recorded. Enzyme linked immunosorbent assay (ELISA) was used to measure the levels of MMP-2,-3,-9, metabolic markers bone alkaline phosphatase(BALP) and tartract-resistant acid phosphapase-5b (TRACP-5b), and the correlation coefficients and significances were calculated between the serum levels of MMP-2,-3,-9 and metabolic markers, the clinical and laboratory indexes. All the data were analyzed by SPSS16.0 for windows Statistical software. The mean number±standard deviation ( x±s) was used to express the measurement data. The t or t'test was adopted for comparison between groups. Chisquare test was used for the comparison of the enumeration data. Linear correlation was used to in analyse. P value<0.05 was considered significant.Results:1 The demographic details and traditional parameters of disease activity in AS: In the group of 30 patients with AS, the mean disease duration at presentation was (81.30±82.25) months, with a mean age of (28.30±7.65) yr, all of them were male, In 20 normal controls, with a mean age of (30.20±5.20) yr, all of them were male. There were no differences between the patients and normal subjects in age and gender (P>0.05). In the group of 30 patients with AS, HLA-B27 were positive in 26 cases (86.7%).2 The incidence of normal bone mass, osteopenia and osteoprosis in 30 AS patients were 16.67%, 46.67% and 36.67% respectively. There were 14 AS patients were in the earlier period of disease, osteopenia and osteoprosis in earlier patients were 42.86% and 28.57% respectively. The BMD in lumbar, femoral neck and greater trochanter of earlier and later period was no statistically significant(P>0.05).3 The incidence of OP in lumbar, femoral neck and greater trochanter in 30 AS patients were 13.33%, 0% and 26.67% respectively. The highest incidence of OP was in greater trochanter (26.67%).4 The levels of serum MMP-2, MMP-3, MMP-9, BALP and TRACP-5b in AS patients were (12393.78±4206.81) ng/L, (43.37±23.82)μg/L, (957243.25±274214.20) ng/L, (28.44±14.56) U/L and (1.87±1.40) U/L respectively, and (8636.81±2645.51) ng/L, (30.32±5.63)μg/L, (737401.46±210988.34)ng/L, (27.77±6.00) U/L and (0.96±0.17) U/L respectively in the healthy control. Compared with the healthy control, the levels of serum MMP-2, MMP-3, MMP-9 and TRACP-5b in AS patients were higher(P<0.05).5 There were positive correlation between MMP-2 and TRACP-5b (r=0.402, P=0.028), and significantly negative correlation between MMP-3 and MMP-9 (r=-0.504, P=0.005), and significantly negative correlation between MMP-2 and Ca (r=-0.549, P=0.002), and positive correlation between MMP-3 and ESR (r=0.418, P=0.021), and positive correlation between BALP and ALKP,BMI(r=0.393, P=0.032;r=0.464, P=0.011).6 AS patients were divided into two groups: OP group (11 patients) and non-OP group (19 patients) according to the complication with OP or not for further comparison. Compared with the non-OP group, the level of serum BALP in OP group was higher(P<0.05),but it showed no statistical differences in MMP-2, MMP-3, MMP-9, TRACP-5b, ESR, CRP, Ca, P, ALKP, PTH, age pathogenesis and BMI(P>0.05).7 In the OP group, there were negative correlation between MMP-3 and BMD in femoral neck (r=-0.635, P=0.049), and negative correlation between MMP-9 and BMD in lumbar(r=-0.405, P=0.035),but positive correlation between BLAP and the BMD in femoral neck(r=0.749, P=0.013).There was no linear correlation between MMP-2 or TRACP-5b with the BMD in different sites(P>0.05).8 There were positive correlation between BMI and the BMD in femoral neck and greater trochanter (r=0.389, P=0.034; r=0.545, P=0.002), but there was no linear correlation between ESR, CRP, Ca, P, ALKP, PTH, age and pathogenesis with the BMD in different sites(P>0.05).Conclusions: 1 AS patients had different degree of bone loss and most of them were complicated with osteopenia or OP, and it appeared in AS patients of earlier period already. Low BMI was one of correlation factors for the secondary OP of AS2 The degree of bone loss was varying in different measurement sites. For a better overall evaluating the BMD, it was necessary to measure BMD in multiple sites and make a comprehensive analysis.3 AS patients had higher bone conversion ratio,bone resorption and bone formation strengthened at the same time, but bone resorption strengthened more obviouslier. High levels of serum MMPs were the correlation factors that resulted in the secondary OP of AS. 4 There was positive correlation between MMP-3 and disease activity of AS. MMP-3 might be one of the potential biology markers of disease activity for AS patients. |
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