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

OBJECTIVE: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSION: 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.