Effect of Pathological and Physiological Loads on Interleukin-1α Protein Production in Porcine Menisci

The meniscus performs several functions for the maintenance of knee joint health, such as load transmission and joint stability. Meniscal lesions have been suggested as a precursor to the onset of osteoarthritis (OA)[1]. Such lesions often lead to surgical removal of the torn portion of the meniscus, increasing cartilage to cartilage contact area. Partial meniscectomies have been shown using finite element analysis and histology to lead to altered and increased mechanical loading on the remaining meniscus and underlying articular cartilage[2,3]. Consequently, pathological compressive strains of more than 15% have been shown to increase proteoglycan breakdown and meniscal matrix degradation[4]. Preliminary investigations in our laboratory have demonstrated an increase in interleukin-1α (IL-1α) gene expression of meniscal explants subjected to pathological levels of dynamic compressive strain [6,7]. This inflammatory cytokine has been attributed to apoptosis and matrix degradation[5]. However, gene expression measurements merely suggest possible matrix remodeling mechanisms and do not necessarily result in protein syntheses from which matrix changes occur. Therefore, the purpose of this study was to quantify protein synthesis of IL-1α in porcine meniscal implants after compressive strain exercises. It was hypothesized that, similar to mRNA expression, protein synthesis for pathologically loaded (0 or 20% dynamic strain) samples would be greater than samples loaded to physiological levels (10% strain).