Differential gene expression in the condylar cartilage of growing rabbits with temporomandibular joint anterior disk displacement-A transcriptomic study

Internal derangement (ID) in the temporomandibular joint (TMJ) comprises a group of clinical problems with relatively high prevalence. However, the temporal changes in gene expression of condylar cartilage during continuous ID remain unclear. The aim of the current study is to investigate by microarray analysis, the differentially-expressed gene pattern in condylar cartilage of rabbits with ID from one to eight weeks of ID progression. Histological results (hematoxylin and eosin staining) indicated that abnormal collagen fiber arrangements, fragmentation of fibrils, and inflammatory cell-infiltration were detected from one to four weeks in joint disc specimens, while newly formed vessels, mucoid degeneration, meniscal tears, and the presence of osteoclasts and osteoblasts were observed at later time points. The microarray analysis revealed 6478 genes among all tested transcripts, to have a greater than two-fold expression change compared to controls. The inflammation-associated gene group including ace and il1β increased rapidly in the early stage of disease and decreased later. In contrast, bone construction-related genes showed low expression levels at first and increased at later period in the ID progression. The current study also found some genes such as hla2g, which have not been previously reported, to be potentially relevant within ID. Our findings provide useful insights into the pathological mechanism of ID in TMJ.