Objective. To determine the relationship between the expression of interleu
kin-1 beta (IL-1 beta) and IL-1 receptor antagonists (IL-1ra) in the subacr
omial bursa and shoulder pain in rotator cuff diseases.
Methods. Synovial specimens were analysed using various methods including r
everse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemist
ry and in situ RT-PCR. Thirty-nine patients with rotator cuff diseases were
candidates. The degree of their shoulder pain was evaluated using a visual
Results. The mRNA expression levels of the cytokines were significantly cor
related with the degree of pain [IL-1 beta: r=0.782; secreted IL-1ra (sIL-1
ra): r=0.756; intracellular IL-1ra (icIL-1ra): r=0.806, P <0.001, respectiv
ely]. The combined results of immunohistochemistry and in situ RT-PCR analy
sis indicated that both synovial lining and sublining cells produce IL-1 be
ta, while synovial lining cells predominantly produce icIL-1ra and sublinin
g cells secrete sIL-1ra.
Conclusions. The differential regulation of the two forms of IL-1ra mRNAs m
ay play an important role in shoulder pain in rotator cuff diseases, regula
ting IL-1-induced subacromial synovitis.