Up-regulation of Cathepsin G in the Development of Chronic Postsurgical Pain: An Experimental and Clinical Genetic Study.

BACKGROUND: Proteases have been shown to modulate pain signaling in the spinal cord and may contribute to the development of chronic postsurgical pain. By using peripheral inflammation in rats as a chronic pain model, the authors identified the deregulation of proteases and their inhibitors as a hallmark of chronic pain development using a genome-wide screening approach. METHODS: A microarray analysis was performed and identified spinal cathepsin G (CTSG) as the most up-regulated gene in rats with persistent hyperalgesia after intraplantar injection of complete Freund's adjuvant (n = 4). Further experiments were performed to elucidate the mechanisms of CTSG-induced hyperalgesia by intrathecally applying specific CTSG inhibitor (n = 10). The authors also evaluated the association between CTSG gene polymorphisms and the risk of chronic postsurgical pain in 1,152 surgical patients. RESULTS: CTSG blockade reduced heat hyperalgesia, accompanied by a reduction in neutrophil infiltration and interleukin 1ß levels in the dorsal horns. In the gene association study, 246 patients (21.4%) reported chronic postsurgical pain at 12-month follow-up. Patients with AA genotypes at polymorphisms rs2070697 (AA-15.3%, GA-24.1%, and GG-22.3%) or rs2236742 (AA-6.4%, GA-20.4%, and GG-22.6%) in the CTSG gene had lower risk for chronic postsurgical pain compared with wild-types. The adjusted odds ratios were 0.67 (95% CI, 0.26 to 0.99) and 0.34 (95% CI, 0.21 to 0.98), respectively. CONCLUSIONS: This study demonstrated that CTSG is a pronociceptive mediator in both animal model and human study. CTSG represents a new target for pain control and a potential marker to predict patients who are prone to develop chronic pain after surgery.

Anti-IL-20 monoclonal antibody suppresses breast cancer progression and bone osteolysis in murine models.

IL-20 is a proinflammatory cytokine involved in rheumatoid arthritis, atherosclerosis, and stroke. However, little is known about its role in breast cancer. We explored the function of IL-20 in tumor growth and metastasis, as well as in clinical outcome. Tumor expression of IL-20 was assessed by immunohistochemical staining among 198 patients with invasive ductal carcinoma of the breast, using available clinical and survival data. IL-20 expression was associated with advanced tumor stage, greater tumor metastasis, and worse survival. Reverse transcription quantitative polymerase chain reaction showed that clinical breast tumor tissue expressed higher levels of IL-20 and its receptors than did nontumorous breast tissue. IL-20 was also highly expressed in breast cancer bone-metastasis tissue. In vitro, IL-20 upregulated matrix metalloproteinase-9, matrix metalloproteinase-12, cathepsin K, and cathepsin G, and enhanced proliferation and migration of breast cancer cells, which were inhibited by anti-IL-20 mAb 7E. In vivo, we generated murine models to evaluate the therapeutic potential of 7E, using luminescence intensity, radiological scans, and micro-computed tomography. 7E reduced tumor growth, suppressed bone colonization, diminished tumor-mediated osteolysis, and lessened bone density decrement in mice injected with breast cancer cells. In conclusion, our results suggest that IL-20 plays pivotal roles in the tumor progression of breast cancer. IL-20 expression in breast cancer tissue is associated with a poor clinical outcome. Anti-IL-20 mAb 7E suppressed bone colonization and decreased osteolytic bone lesions. Therefore, IL-20 may be a novel target in treating breast tumor-induced osteolysis.