Analysis Of Differential Express Genes In The Hip Joint Ligament Of Ankylosing Spondylitis Patients

Ankylosing spondylitis (AS), is a seronegative spondyloarthritis(SpA) disease that causes axial skeletal inflammation that includes the entheses and sacroiliac joints, with variable involvement of the peripheral joints. Due to erosion and destruction of articular cartilage and bone and pathologic new bone formation can cause the stiff thoracolumbar spine and hip, eventually leading to loss of joint function. The pathogenesis of AS is not fully understood. Ankylosing spondylitis typically occurred in young adults, most commonly in males (male-female ratio, 3:1) of 20 to 40 years. Literatures have reported that 30% to 50% of patients with AS exhibited involvement of the hips, and among those with the hips affected, 91% presented bilaterally. The ligament ossification occurs in advanced stage, resulting in spine and hip joint ankylosis and deformities.Particularly ligament ossification in the hip joint will cause serious dysfunction, giving the patient's life and work great suffering. Given the progress in studying the pathogenesis of AS, especially in the hip ligament ossification mechanism, these may prove to be more fruitful approaches to early diagnosis and effective treatment ligament ossification.ObjectiveOur study aims at preliminary approach the pathological mechanism of abnormal bone formation of ankylosing spondylitis patient ligament, which may be one of the important clue and foundation to the study on the inhibition of ankylosing spondylitis hip ligament ossification and development of therapeutic targets controlling ossification process.MethodWe make use of gene chip technology to study the hip ligament gene expression profiles of ankylosing spondylitis patients and normal person to find the difference between the two groups'genes, and combining the differentially expressed genes bioinformatics analysis means to choose five significant expression gene in contrast to normal (two up-regulated expression genes: B4GALT3, RBP5; three down-regulated genes: 3PDLIM3, MFAP5, FLJ90650) for the outcome of gene chip.We studied 7 patients with hip arthroplasty in our department in 2009-2010.Who fulfilled the modified 1984 New York criteria for a diagnosis of AS. 5 cases of femoral neck fractures patients with hip arthroplasty (had no personal or family history of inflammatory Arthritis,exclude other types of bone and joint diseases,and none were related to each other or to the patients.) are acted as a healthy control group. We detected the expression of mRNA level by using RT-PCR, and the methods of Western-blot and immunohistochemistry to test their protein changes.ResultsGene chip results of AS group and healthy control group show that among the known functional genes: P <0.05, there are different in 434 genes, of which 238 up-regulated genes, down-regulated genes 196; P <0.01, there are different in gene 43, of which 31 up-regulated genes, of which 12 down-regulated genes. RT-PCR results showed that B4GALT3 gene expression in the AS group is 4.90 times (p<0.05) the healthy control group, and RBP5 gene expression in the AS group is 2.92 (p<0.05) times the healthy control group, HLA-B27 gene expression in the AS group is 12.81 (p<0.05) times the healthy control group; MFAP5gene expression in the healthy control group is 12.49 times (p<0.05) the AS group, FLJ90650 gene expression in the healthy control group is 6.04 times (p<0.05) the AS group, PDLIM3 gene expression in the healthy control group is 15.05 times (p<0.05) the AS group. Western Blot and immunohistochemical results are in agreement with the results of RT-PCR.ConclusionHip joint ligaments ossification of ankylosing spondylitis patient change in the various aspects. B4GALT3 gene stimulates the excessive synthesis of keratin sulfate in their ligaments to promote calcium deposition in the extracellular matrix, FLJ90650 gene, through the specific eliminate some protein,so that hip joint ligament abnormally ossify; RBP5, MFAP5, PDLIM3 gene of ankylosing spondylitis patients may play an important role in the process of hip ligament ossification. Both of these genes are not reported and the exact mechanism remains to be further study.