Altered Gene and Protein Expressions in Torn Rotator Cuff Tendon Tissues in Diabetic Patients

To analyze and compare the gene and protein expression characteristics in torn rotator cuff tendon tissues between diabetic and nondiabetic patients.

This was a pilot study. Twelve samples of rotator cuff tendon tissue from diabetic patients (mean age, 62.3 ± 9.9 years) and 12 age- and sex-matched nondiabetic tendon tissues (62.3 ± 9.9 years) were acquired from the torn tendon end of medium rotator cuff tears during arthroscopic surgery, after applying the same inclusion and exclusion criteria. Expressions of various genes of interest, including collagens I and III, matrix metalloprotease (MMP)-2, MMP-3, MMP-9, MMP-13, interleukin (IL)-1, IL-6, insulin-like growth factor-1, vascular endothelial growth factor, tenomodulin, tumor necrosis factor-α, and p53, were analyzed with real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). In addition, immunohistochemistry and western blot assay were performed for the genes that revealed significantly different expressions in real-time qRT-PCR between groups.

Gene expression levels of MMP-9, MMP-13, IL-6, and tenomodulin were significantly higher in the diabetic than in the nondiabetic group by real-time qRT-PCR analyses (P = .011, .004, .009, and .010, respectively). The density of cells expressing MMP-9 and IL-6 was significantly increased in the torn tendons of the diabetic patients on immunohistochemical analysis, and the density of MMP-9 and IL-6 protein expressions was significantly higher in the diabetic group on western blot (P = .018 and .044, respectively).

Diabetic torn cuff tendon tissues showed MMP-9 and IL-6 overexpressions compared with controls.

The overexpressions of MMP-9 and IL-6 may be one of the explanations for the high healing failure rate after rotator cuff repair in the diabetic patients.