Date of this Version
Chemokines are thought to play an important role in several aspects of bone metabolism including the recruitment of leukocytes and the formation of osteoclasts. We investigated the impact of diabetes on chemokine expression in normal and diabetic fracture healing. Fracture of the femur was performed in streptozotocin-induced diabetic and matched normoglycemic control mice. Microarray analysis was carried out and chemokine mRNA levels in vivo were assessed. CCL4 were examined in fracture calluses by immunohistochemistry and the role of TNF in diabetes-enhanced expression was investigated by treatment of animals with the TNF-specific inhibitor, pegsunercept. In vitro studies were conducted with ATDC5 chondrocytes. Diabetes significantly upregulated mRNA levels of several chemokines in vivo including CCL4, CCL8, CCL6, CCL11, CCL20, CCL24, CXCL2, CXCL5 and chemokine receptors CCR5 and CXCR4. Chondrocytes were identified as a significant source of CCL4 and its expression in diabetic fractures was dependent on TNF (P < 0.05). TNF-α significantly increased mRNA levels of several chemokines in vitro which were knocked down with FOXO1 siRNA (P < 0.05). CCL4 expression at the mRNA and proteins levels was induced by FOXO1 over-expression and reduced by FOXO1 knockdown. The current studies point to the importance of TNF-α as a mechanism for diabetes enhanced chemokine expression by chondrocytes, which may contribute to the accelerated loss of cartilage observed in diabetic fracture healing. Moreover, in vitro results point to FOXO1 as a potentially important transcription factor in mediating this effect.
NOTICE: this is the author’s version of a work that was accepted for publication in Bone. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Bone, Vol 53, Issue 1, March 2013, DOI: 10.1016/j.bone.2012.12.006
Animals, Chemokines, Chondrocytes, Diabetes Mellitus, Experimental, Fracture Healing, Immunohistochemistry, Mice, RNA Interference, RNA, Messenger, Up-Regulation
Alblowi, J., Tian, C., Kayal, R. A., McKenzie, E., Behl, Y., Gerstenfeld, L., Einhorn, T. A., & Graves, D. T. (2013). Chemokine Expression Is Upregulated in Chondrocytes in Diabetic Fracture Healing. Bone, 53 (1), 294-300. http://dx.doi.org/10.1016/j.bone.2012.12.006
Date Posted: 31 March 2015
This document has been peer reviewed.