Immunohistochemical panel of degenerated articular discs from patients with temporomandibular joint osteoarthritis

Temporomandibular joint osteoarthritis (TMJOA) is a progressive degenerative disease caused by imbalance between anabolic and catabolic stimuli.

The aim of this study was to evaluate histopathological changes, collagen degeneration and the expression of eleven TMJOA biomarkers in articular discs.

Specimens were obtained from eight female patients submitted to discectomy. Discs were divided into anterior band (AB), intermediate zone (IZ) and posterior band (PB) for computerised histomorphometric analyses. Each was assigned a histopathological degeneration score (HDS). Collagen degeneration was assessed with Picrosirius-polarisation method. Biomarkers were evaluated through immunohistochemistry, including IGF-1, OPG, VEGF, TNF-α, FGF-23, IHH, MMP-3, MMP-9, TGF-β₁ , BMP-2 and WNT-3. Image processing software was used to calculate average immature collagen ratios and immunostained areas. Spearman rank tests were applied to verify correlations, with significance level of 0.05.

The HDS showed negative correlation with expression of VEGF in IZ and PB (P < .05) and positive with TNF-α in AB (P < .01). Collagen degeneration correlated with TGF-β₁ (P < .05), BMP-2 (P < .01) and IHH (P < .05) immunostained areas in the IZ; TGF-β_1, BMP-2 and IHH expression correlated among each other in AB and IZ (P < .05).

Angiogenesis and tissue fragmentation may result from aberrant physiologic responses mediated by VEGF and TNF-α, compromising TMJ discs during OA progression. The expression of TGF-β_1, BMP-2 and IHH could be related to collagen degeneration in displaced discs and may participate in TMJOA pathogenesis.