Temporomandibular joint (TMJ) disc displacement is one of the most significant subtypes of temporomandibular joint disorders, but its etiology and mechanism are poorly understood. In this study, we elucidated the mechanisms by which destruction of inflamed collagen fibrils induces alterations in the mechanical properties and positioning of the TMJ disc. By constructing a rat model of TMJ arthritis, we observed anteriorly dislocated TMJ discs with aggravated deformity in vivo from five weeks to six months after a local injection of Freund's complete adjuvant. By mimicking inflammatory conditions with interleukin-1 beta in vitro, we observed enhanced expression of collagen-synthesis markers in primary TMJ disc cells cultured in a conventional two-dimensional environment. In contrast, three-dimensional (3D)-cultivated disc cell sheets demonstrated the disordered assembly of inflamed collagen fibrils, inappropriate arrangement, and decreased Young's modulus. Mechanistically, inflammation-related activation of the nuclear factor kappa-B (NF-κB) pathway occurs during the progression of TMJ arthritis. NF-κB inhibition reduced the collagen fibril destruction in the inflamed disc cell sheets in vitro, and early NF-κB blockade alleviated collagen degeneration and dislocation of the TMJ discs in vivo. Therefore, the NF-κB pathway participates in the collagen remodeling in inflamed TMJ discs, offering a potential therapeutic target for disc displacement.
Animals ; NF-kappa B/metabolism* ; Temporomandibular Joint Disorders/pathology* ; Temporomandibular Joint Disc/metabolism* ; Rats ; Rats, Sprague-Dawley ; Disease Models, Animal ; Male ; Collagen/metabolism* ; Cells, Cultured ; Joint Dislocations/pathology* ; Interleukin-1beta ; Arthritis, Experimental

Collagen is the building component of temporomandibular joint (TMJ) discs and is often affected by inflammation in temporomandibular disorders.The macromechanical properties of collagen are deteriorated by chronic inflammation.However,the mechanism by which inflammation influences disc function remains unknown.The relationship between the ultrastructure and nanomechanical properties of collagen in inflamed discs should be clarified.Seven-week-old female Sprague-Dawley rats were randomly divided into two groups.Chronic TMJ inflammation was induced by intra-articular injection of complete Freund's adjuvant,and samples were harvested after 5 weeks.Picrosirius staining revealed multiple colours under polarized light,which represented alternative collagen bundles in inflamed discs.Using atomic force microscopy scanning,the magnitude of Young's modulus was reduced significantly accompanied with disordered collagen fibril arrangement with porous architecture of inflamed discs.Transmission electron microscopy scanning revealed a non-uniform distribution of collagen fibres,and oversized collagen fibrils were observed in inflamed discs.Fourier transform infrared microspectroscopy revealed a decrease in 1 338 cm-1/amide Ⅱ area ratio of collagen in different regions.The peak positions of amide Ⅰ and amide Ⅱ bands were altered in inflamed discs,indicating collagen unfolding.Our results suggest that sustained inflammation deteriorates collagen structures,resulting in thedeterioration of the ultrastructure and nanomechanical properties of rat TMJ discs.

Objective: To analyze influencing factors of in-stent restenosis after coronary artery stent implantation, to provide theoretical support for clinical prevention of restenosis. Methods: Clinical data of 123 patients, who received coronary artery stent implantation in our hospital from Mar 2011 to Sep 2013 and received coronary angiography follow-up one year after operation, were retrospectively analyzed. In-stent restenosis was regarded as stenosis of inner diameter of implanted stent≥50%, so patients were divided into restenosis group (n=35) and non-restenosis group (n=88). Multi-factor Logistic regression analysis was used to analyze influencing factors of coronary in-stent restenosis. Results: Compared with non-restenosis group, there were significant reductions in serum level of total bilirubin [(14.02±6.76) μmol/L vs. (10.90±4.51) μmol/L] and stent diameter [(3.06±0.86) mm vs. (2.87±0.44) mm] in restenosis group, P<0.01 both. Multi-factor Logistic regression analysis indicated that blood glucose level was independent risk factor for restenosis after coronary artery stent implantation (OR=2.545, P=0.035), while stent diameter and serum level of total bilirubin were its protective factors (OR=0.857, 0.850, P<0.05 both). Conclusion: Blood glucose level is an independent risk factor for restenosis after coronary artery stent implantation, while stent diameter and serum level of total bilirubin are its protective factors.

Objective To investigate the role of different culture densities of embryoid bodies (EBs) in cardiac dif-ferentiation of mouse embryonic stem cells (ESCs). Methods The mouse ESCs were cultured in hanging drops for 3 days, followed by another 2 days for suspension culture to form EBs. Suspended EBs of different densities (60 or 120 EBs/60 mm tissue culture dish) were transferred onto tissue culture plates. The cardiac specific troponin T (TnT) was detected by immu-nocytochemistry. The percentage of beating EBs was calculated at different time points. The mRNA expression of cardiac spe-cific transcriptional factors Nkx2.5, GATA4 and cardiac specific proteinsβ-MHC and ANF were detected by RT-PCR. The protein expressions of TnT and p38 were detected by Western-blot assay. Results Spontaneously beating EBs were posi-tively stained with TnT. There were significantly higher percentage of beating EBs, higher gene expression levels of Nkx 2.5, GATA4,β-MHC and ANF and higher protein expression of TnT in high density culture group than those of low density cul-ture group (P＜0.05). Furthermore, there was significantly higher activity of p38 pathway in high density culture group than that of low density culture group. And the percentages of beating EBs and TnT protein expression were decreased by p 38 pathway inhibitor SB203580. Conclusion The culture density of EBs is important in regulating the cardiac differentiation of ESCs. The high cell-density density culture of EBs enhances the cardiac differentiation of ESCs, which might be mediated by p38 signaling pathway.