Perforation of rotator cuff increases interleukin 1beta production in the synovium of glenohumeral joint in rotator cuff diseases.

Abstract

To study the hypothesis that perforation of the rotator cuff increases the degree of inflammation in the synovium of the glenohumeral joint in rotator cuff diseases. Thirty-five synovial specimens in the glenohumeral joint of patients with rotator cuff diseases were examined. They were obtained during surgery and divided into 2 groups on the basis of the presence or absence of rotator cuff perforation, i.e., perforating and nonperforating tears. The expression levels of inflammatory cytokine mRNA of interleukin 1beta (IL-1beta) and 2 forms (secreted type and intracellular type) of IL-1 receptor antagonist (IL-1ra) were measured by reverse transcriptase polymerase chain reaction (RT-PCR). The protein level of IL-1beta was determined by Western blot analysis. IL-1beta producing cells were also identified by in situ RT-PCR and immunohistochemistry. In perforating tears cytokine mRNA in the glenohumeral synovium was more significantly expressed than in nonperforating tears. Also, higher levels of IL-1beta protein were detected in perforating tears. Perforation of the rotator cuff increases IL-1beta production in the glenohumeral joint, enhancing inflammatory intensity at the site. These findings suggest the possibility that glenohumeral synovitis in rotator cuff diseases may be a factor for the development of glenohumeral arthropathy.