J. Ke

Insulin-like growth factor-1 boosts the developing process of condylar hyperplasia by stimulating chondrocytes proliferation.

OBJECTIVE The etiology of Condylar hyperplasia (CH) of human temporomandibular joint (TMJ) remains largely unknown. Our previous study has demonstrated that enriched insulin-like growth factor-1(IGF-1) was expressed in the proliferation and hypertrophic layers of CH cartilage. Accordingly, this study was aimed to investigate whether IGF-1 regulates CH chondrocytes proliferation in condylar cartilage overgrowth and explore the molecular mechanism of IGF-1 involved in. METHODS Chondrocytes were isolated from 6 CH and 3 normal cartilage (NC) specimens and cultured in alginate beads or monolayer, treated with IGF-1 or specific inhibitors such as 7-[trans-3-[(azetidin-1-yl)methyl]cyclobutyl]-5-(3-benzyloxyphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-amine (NVP-AEW541), U0126, and LY294002. Thereafter, cellular proliferation capacity was evaluated by Cell Viability Analyzer (alginate beads culture) or 3-(4,5-dimethylthiazo(-2-yl)-2,5-diphenyltetrazolium bromide (MTT) (monolayer culture). Gene expression levels of IGF-1, IGF-1 receptor (IGF-1R), collagen type II, type X and those genes associated with proliferation were evaluated by realtime PCR. Protein levels of IGF-1 and IGF-1R synthesized by CH chondrocytes were accessed by enzyme-linked immunosorbent assay (ELISA) and western blotting. RESULTS CH chondrocytes enhanced cellular proliferation capacity and expressed significantly higher levels of messenger RNA (mRNA) and protein expressions of IGF-1 and IGF-1R, as compared with NC chondrocytes. Furthermore, enriched IGF-1 enhanced CH chondrocytes proliferation, up-regulated the expressions of specific genes associated with cellular proliferation and elevated the gene expression of collagen type II A1 (COL2A1). Besides, IGF-1-mediated CH chondrocytes proliferation mainly depended on the mitogen-activated protein kinase (MAPK)-ERK pathway. CONCLUSIONS IGF-1 promotes human TMJ cartilage overgrowth in the developing process of CH by enhancing chondrocytes proliferation via MAPK-ERK pathway.

Up-regulation of proteoglycan 4 in temporomandibular osteoarthritic synovial cells by hyaluronic acid

BACKGROUND Hyaluronic acid (HA) injection is widely used in the treatment of temporomandibular joint (TMJ) osteoarthritis (OA). Proteoglycan 4 (PRG4) is another joint lubricant that protects surface of articular cartilage. But few studies had explored the role of HA in regulation of PRG4 expression in TMJ OA. In this study, the effects of HA on the expression of PRG4 in osteoarthritic TMJ synovial cells were investigated in hypoxia, which was similar to the TMJ physiologically. METHODS Synovial cells were isolated from the TMJ OA patients and were treated with or without HA under normoxia or hypoxia for indicated time periods. The proliferation of synovial cells was measured using Cell Counting Kit-8 (CCK-8). The gene expression of HAS2, VEGF, and PRG4 was detected by quantitative real-time PCR, and the secretion of PRG4 and VEGF was assayed by enzyme-linked immunosorbent assay (ELISA). Immunofluorescence was used to examine the protein expression of hypoxia-induced factor-1α (HIF-1α). RESULTS Hyaluronic acid markedly increased the proliferation of osteoarthritic synovial cells in hypoxia. The expression of HAS2 and PRG4 mRNA of osteoarthritic synovial cells under hypoxia was enhanced by HA treatment. However, HA had no effect on reducing the VEGF and HIF-1α expression in synovial cells in hypoxia. CONCLUSIONS Hyaluronic acid could promote the expression of HAS2 and PRG4, but could not modulate HIF-1α and VEGF expression of TMJ osteoarthritic synovial cells in hypoxia.

Mutual effect between neuropeptides and inflammatory cytokines in neurogenic SMSCs of human temporomandibular joint

In temporomandibular disorders (TMD), pain takes place when neuropeptides stimulate synovial tissue to produce several cytokines such as interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, which activate neurons and glia of synovial membrane at the bilaminar regions of temporomandibular joint (TMJ). It has been reported that, after neurogenic differentiation, the synovial mesenchymal stem cells (SMSCs), deriving from TMJ, possess the same cytological features as the neuronal cells. This study examined the ability of substance P (SP) and calcitonin gene-related peptide (CGRP) to stimulate SMSCs and neurogenic SMSCs secreting inflammatory cytokines during TMD, evaluated the mutual effects of inflammatory cytokines and neuropeptides and tested the analgesic effect of hyaluronic acid (HA). The levels of IL-1β, IL-6 and TNF-α in SMSCs and neurogenic SMSCs in the presence of neuropeptides were measured by ELISA. SP and CGRP produced by SMSCs and neurogenic SMSCs were determined by RT-PCR and Western blotting. The results showed that the expression of SP and CGRP was significantly enhanced in the neurogenic SMSCs in response to IL-1β, IL-6 and TNF-α, and the effect was remarkably inhibited by HA. IL-1β, IL-6 and TNF-α, in return, could be enhanced in the neurogenic SMSCs upon stimulation by SP and CGRP. Neuropeptides and inflammatory cytokines might work mutually on the TMD pain. The HA-mediated analgesic effect may be implicated in the inhibition of SP and CGRP expression in neurogenic SMSCs.SummaryIn temporomandibular disorders (TMD), pain takes place when neuropeptides stimulate synovial tissue to produce several cytokines such as interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, which activate neurons and glia of synovial membrane at the bilaminar regions of temporomandibular joint (TMJ). It has been reported that, after neurogenic differentiation, the synovial mesenchymal stem cells (SMSCs), deriving from TMJ, possess the same cytological features as the neuronal cells. This study examined the ability of substance P (SP) and calcitonin gene-related peptide (CGRP) to stimulate SMSCs and neurogenic SMSCs secreting inflammatory cytokines during TMD, evaluated the mutual effects of inflammatory cytokines and neuropeptides and tested the analgesic effect of hyaluronic acid (HA). The levels of IL-1β, IL-6 and TNF-α in SMSCs and neurogenic SMSCs in the presence of neuropeptides were measured by ELISA. SP and CGRP produced by SMSCs and neurogenic SMSCs were determined by RT-PCR and Western blotting. The results showed that the expression of SP and CGRP was significantly enhanced in the neurogenic SMSCs in response to IL-1β, IL-6 and TNF-α, and the effect was remarkably inhibited by HA. IL-1β, IL-6 and TNF-α, in return, could be enhanced in the neurogenic SMSCs upon stimulation by SP and CGRP. Neuropeptides and inflammatory cytokines might work mutually on the TMD pain. The HA-mediated analgesic effect may be implicated in the inhibition of SP and CGRP expression in neurogenic SMSCs.

Association of COL1A1 polymorphism with subchondral bone degeneration of the temporomandibular joint.

The G/T polymorphism of the COL1A1 gene exhibits a clinically significant influence on bone remodelling, leading to a predisposition to degenerative diseases. The enhancement of bone turnover and further loss of bone mass are thought to be the primary pathological changes in the early degenerative course of temporomandibular joint osteoarthritis (TMJ OA), with the appearance of low-density lesions. Thus, it was hypothesized that this polymorphism may also affect this type of bone lesion in TMJ OA. A total of 130 TMJ OA patients with low-density lesions (cortical bone erosion, condylar head resorption, cyst-like lesion) and 186 healthy individuals were recruited. DNA samples were extracted from buccal mucosa swabs; genotyping was performed by high-resolution melting assay. The distribution of genotypes in these groups was compared using a multivariate logistic regression model. No significant differences in the distributions of TT and TG genotypes were observed between the groups (P>0.05). Significance was detected for GG homozygous carriers (P=0.043); this genotype might be a risk factor for this type of low-density lesion (odds ratio 1.643, 95% confidence interval 1.016-2.658). This study indicates that the GG genotype might be a risk factor for low-density lesions in the TMJ.

Reconstruction of the oral commissure in patients with unilateral transverse facial cleft

The normal commissure is not a simple joint of the upper and lower lip, but a triangular mucosal area. To reconstruct a symmetrical oral commissure in patients with a unilateral transverse facial cleft, we designed composite vermilion flaps, including triangular flaps. We retrospectively studied 17 patients with unilateral transverse facial clefts from 2013-2016. Three-dimensional images were obtained with a 3-dimensional photogrammetry system at the 1-year follow-up, and we used an anthropometric method to evaluate the postoperative symmetry of the commissure. No obvious deformity was found during the follow-up examination, and comparison of the cleft and non-cleft sides by the paired samples t test showed that in all cases both horizontally and vertically symmetrical commissures had been achieved.

Cone–beam computed tomographic analysis of maxillary and mandibular changes after high condylectomy combined with orthodontic treatment for active unilateral condylar hyperplasia

Our aim was to evaluate the efficacy of high condylectomy combined with orthodontic treatment for active unilateral condylar hyperplasia in 25 affected patients, by an analysis of the maxillary and mandibular changes on cone-beam computed tomography (CT). High condylectomy was the sole operative treatment. Variables that reflected the canting of the occlusal plane, the height of the maxillary complex, the buccolingual angulation of the maxillary first molar, the height of the ramus, the total length of the mandible, and the deviation of the chin were measured and compared between the two sides and between time intervals: preoperatively (T1) and the end of treatment (T2). The differences between time intervals in the deviation of the chin (p<0.001) and the canting of the occlusal plane (p<0.001) were significant, but there were no significant differences in the height of the ramus (p=0.476) and the total length of the mandible (p=0.838) between the affected and unaffected sides at T2. There were significant differences between time intervals in the buccolingual angulation on the unaffected side and the height of the maxillary complex on the affected side (p<0.001). Facial asymmetry was corrected and the occlusal plane was improved. In conclusion, high condylectomy as the sole operative treatment combined with orthodontic treatment can provide an alternative method for correction of facial asymmetry associated with active unilateral condylar hyperplasia.

HMGB1‐induced angiogenesis in perforated disc cells of human temporomandibular joint

High mobility group 1 protein (HMGB1), a highly conserved nuclear DNA‐binding protein and inflammatory mediator, has been recently found to be involved in angiogenesis. Our previous study has demonstrated the elevation of HMGB1 in the tissue of perforated disc of temporomandibular joint (TMJ). Here, we investigated a novel mediator of HMGB1 in regulating hypoxia‐inducible factor‐1α (HIF‐1α) and vascular endothelial growth factor (VEGF) to mediate angiogenesis in perforated disc cells of TMJ. HMGB1 increased the expression of HIF‐1α and VEGF in a dose‐ and time‐dependent manner in these cells. Moreover, immunofluorescence assay exhibits that the HIF‐1α were activated by HMGB1. In addition, HMGB1 activated extracellular signal‐related kinase 1/2 (Erk1/2), Jun N‐terminal kinase (JNK), but not P38 in these cells. Furthermore, both U0126 (ErK inhibitor) and SP600125 (JNK inhibitor) significantly suppressed the enhanced production of HIF‐1α and VEGF induced by HMGB1. Tube formation of human umbilical vein endothelial cells (HUVECs) was significantly increased by exposure to conditioned medium derived from HMGB1‐stimulated perforated disc cells, while attenuated with pre‐treatment of inhibitors for VEGF, HIF‐1α, Erk and JNK, individually. Therefore, abundance of HMGB1 mediates activation of HIF‐1α in disc cells via Erk and JNK pathway and then, initiates VEGF secretion, thereby leading to disc angiogenesis and accelerating degenerative change of the perforated disc.

Sialoendoscopy combined with an internal stent and postoperative massage as a comprehensive treatment of delayed I131-induced parotitis

A common complication of radioiodine (I131) treatment of thyroid cancer is parotitis. Here we describe our clinical experience in treating delayed I131-induced parotitis using sialoendoscopy together with an internal stent and postoperative massage. In this retrospective cohort study we reviewed 32 patients who were treated in that way under general anaesthesia between July 2010 and March 2015. Their age, sex, and the time to development of the parotitis were collected from the hospitals database. All patients were evaluated using a visual analogue scale (VAS), sialography, and computed tomography preoperatively. The analyses of VAS scores were made during postoperative follow-up visits. We used the paired Students t test and one-way ANOVA to assess the significance of differences, and probabilities of < 0.05 were accepted as significant. The mean (SD) age of the 32 patients was 50 (11) years, and they developed symptoms of delayed parotitis after a mean (SD) of 12 (11) months. The mean time between treatment with I131 and sialoendoscopy was 26 (10) months. Ductal stenosis was the most common sialoendoscopic feature, together with mucous plugs and fibrosis. Fifty of the 56 ducts were successfully dilated by sialoendoscopy, and VAS scores significantly decreased from a preoperative 7.3 (1.1) to a postoperative 3.3 (2.1) (p=0.000) during follow-up of 3 - 41 months. Sialoendoscopic interventions combined with an internal stent and postoperative massage may be optimal comprehensive treatment for delayed I131-induced parotitis.