Increased expression of alpha 1-anti-trypsin in the synovial tissues of patients with ankylosing spondylitis.

OBJECTIVES

Evidence indicates that the hyperplasia and inflammation of synovial tissues are significantly related to the pathogenic process of ankylosing spondylitis (AS). Using a proteomics approach, we detected a significantly increased expression of alpha 1-anti-trypsin (ATA1) in synovial membranes of patients with AS.

METHODS

We continued to investigate the expression level and location of ATA1 in synovial tissue of AS. We also investigated the genetic effect of the gene encoding ATA1 on AS. Western blot analysis was applied to determine the expression of ATA1 in synovial tissues by comparing the expression profiles of AS (n=8), rheumatoid arthritis (RA, n=9) and osteoarthritis (OA, n=9) samples. Immunohistochemistry was used to localise the expression of ATA1 in the synovial membrane. Taqman method was used to genotype tag SNPs (rs2753934, rs2749531 and rs6575424) with 56 AS cases, 260 RA cases and 160 healthy controls.

RESULTS

We detected an increased expression of ATA1 in synovial membranes of AS as compared with samples from RA and OA. We immuno-localised the significant expression of ATA1 in AS tissues. No significant association was found between the ATA1 polymorphism and AS or RA. Haplotype analysis did not reveal a haplotype to be associated with AS or RA.

CONCLUSIONS

It has been reported that ATA1 is related with inflammation and new bone formation, two important features of AS. The current findings suggest that ATA1 contributes to the pathogenesis of AS by up-regulating the gene expression in the synovial tissues.