Oxidative stress and temporomandibular joint disorders

Association between genetically plasma proteins and osteonecrosis: a proteome-wide Mendelian randomization analysis

Background

Previous studies have explored the role of plasma proteins on osteonecrosis. This Mendelian randomization (MR) study further assessed plasma proteins on osteonecrosis whether a causal relationship exists and provides some evidence of causality.

Methods

Summary-level data of 4,907 circulating protein levels were extracted from a large-scale protein quantitative trait loci study including 35,559 individuals by the deCODE Genetics Consortium. The outcome data for osteonecrosis were sourced from the FinnGen study, comprising 1,543 cases and 391,037 controls. MR analysis was conducted to estimate the associations between protein and osteonecrosis risk. Additionally, Phenome-wide MR analysis, and candidate drug prediction were employed to identify potential causal circulating proteins and novel drug targets.

Results

We totally assessed the effect of 1,676 plasma proteins on osteonecrosis risk, of which 71 plasma proteins had a suggestive association with outcome risk (P < 0.05). Notably, Heme-binding protein 1 (HEBP1) was significant positively associated with osteonecrosis risk with convening evidence (OR, 1.40, 95% CI, 1.19 to 1.65, P = 3.96 × 10-5, P FDR = 0.044). This association was further confirmed in other MR analysis methods and did not detect heterogeneity and pleiotropy (all P > 0.05). To comprehensively explore the health effect of HEBP1, the phenome-wide MR analysis found it was associated with 136 phenotypes excluding osteonecrosis (P < 0.05). However, no significant association was observed after the false discovery rate adjustment.

Conclusion

This comprehensive MR study identifies 71 plasma proteins associated with osteonecrosis, with HEBP1, ITIH1, SMOC1, and CREG1 showing potential as biomarkers of osteonecrosis. Nonetheless, further studies are needed to validate this candidate plasma protein.

Lycopene as a Potential Anti-inflammatory Therapeutic Agent for Temporomandibular Joint Disorders: A Narrative Review

Temporomandibular joint disorder is a common condition characterized by jaw joint and muscle pain and its treatment is often multifaceted. While conventional treatment modalities exist for the same, interest has grown in exploring alternative therapies such as antioxidants for their potential analgesic properties. The prospective therapeutic use of lycopene, a naturally occurring antioxidant present in tomatoes and other fruits, as an anti-inflammatory therapeutic modality in the management of temporomandibular joint problems is examined in this narrative review.

The evaluation of oxidative stress and inflammation markers in serum and saliva of the patients with temporomandibular disorders

Background/aim

Temporomandibular Disorders (TMD), as in the occurrence of many diseases, have been associated with oxidative stress (OS) resulting from the disruption of antioxidant mechanisms and the accumulation of reactive oxygen species in tissues. This study was designed to compare salivary and serum OS and inflammation markers of individuals with TMD and healthy subjects.

Materials and methods

A prospective cross-sectional study was conducted. Twenty-seven TMD patients diagnosed with disc displacement (DD) according to Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and 17 healthy subjects were enrolled in the study. Prior to any treatment, serum, and saliva samples were taken from the patients and centrifuged, and stored at -80 °C until analyzed. All samples were examined for Interleukin-6 (IL-6), Malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHdG) concentrations.

Results

There was no significant difference between the groups regarding median values of 8-OHdG, IL-6, and MDA (p > 0.05). When the relationship between serum and salivary 8-OHdG, IL-6, and MDA levels in all subjects was evaluated, there was a strong positive correlation between the levels of 8-OHdG and IL-6 in the serum (r = 0.752, p <0.001). In the study group, when the relationship between pain levels and serum and saliva 8-OHdG, IL-6, and MDA levels was assessed, a positive and strong correlation was found between the levels of 8-OHdG and IL-6 in serum.

Conclusion

Although the strong correlation between pain scores and serum 8-OHdG and MDA levels supports the hypothesis that inflammation and OS mechanisms may be interrelated, according to the results of the study, inflammatory and OS markers in patients with TMD were not different from healthy individuals.

BNTA attenuates temporomandibular joint osteoarthritis progression by directly targeting ALDH3A1: An in vivo and in vitro study

BNTA is known to have a therapeutic effect on knee osteoarthritis and inflammatory osteoclastogenesis. However, the protective effect of BNTA regarding temporomandibular mandibular joint osteoarthritis (TMJOA) and its underlying mechanism and physiological target remains unclear. In the present study, BNTA ameliorated cartilage degradation and inflammation responses in monosodium iodoacetate (MIA)-induced TMJOA in vivo. In IL-1β-induced condylar chondrocytes, BNTA prevents oxidative stress, inflammatory responses and increasing synthesis of cartilage extracellular matrix through activating nuclear factor-E2-related factor 2 (NRF2) signaling. Suppression of NRF2 signaling abolishes the protective effect of BNTA in TMJOA. Notably, BNTA may bind directly to ALDH3A1 and act as a stabilizer, as evidenced by drug affinity responsive target stability assay (DARTS), cellular thermal shift assay (CETSA) and molecular docking results. Further investigation of the underlying molecular and cellular mechanism infers a positive correlation of ALDH3A1 regulating NRF2 signaling. In conclusion, BNTA may attenuate TMJOA progression via the ALDH3A1/NRF2 axis, inferring that BNTA is a therapeutic target for treating temporomandibular mandibular joint osteoarthritis.

Biliary Metabolome Profiling for Evaluation of Liver Metabolism and Biliary Tract Function Related to Organ Preservation Method and Degree of Ischemia in a Porcine Model

The development of surgical techniques, immunosuppressive strategies and new organ preservation methods have meant that transplant centers have to face the problem of an insufficient number of organs for transplantation concerning the constantly growing demand. Therefore, using organs from expanded criteria donors and developing new analytical solutions to find parameters or compounds that would allow a more efficient assessment of organ quality before transplantation are options for meeting this challenge. This study proposed bile metabolomic analysis to evaluate liver metabolism and biliary tract function depending on the organ preservation method and degree of warm ischemia time. The analyses were performed on solid-phase microextraction-prepared bile samples from porcine model donors with mild (heart beating donor [HBD]) and moderate warm ischemia (donation after circulatory death [DCD]) grafts subjected to static cold storage (SCS) or normothermic ex vivo liver perfusion (NEVLP) before transplantation. Bile produced in the SCS-preserved livers was characterized by increased levels of metabolites such as chenodeoxycholic acid, arachidonic acid and 5S-hydroxyeicosatetraeonic acid, as well as saturated and monounsaturated lysophosphatidylcholines (LPC). Such changes may be associated with differences in the bile acid synthesis pathways and organ inflammation. Moreover, it has been shown that NEVLP reduced the negative effect of ischemia on organ function. A linear relationship was observed between levels of lipids from the LPC group and the time of organ ischemia. This study identified metabolites worth considering as potential markers of changes occurring in preserved grafts.

Laser-Induced Differentiation of Human Adipose-Derived Stem Cells to Temporomandibular Joint Disc Cells

BACKGROUND AND OBJECTIVES

Temporomandibular disorder (TMD) is an incapacitating disease with temporomandibular joint (TMJ) disc degenerative changes in patients. Despite several research attempts to find a definitive treatment, there is no evidence of a permanent solution. The objective of the current study was to observe the role of 660 nm diode laser in the differentiation of human adipose-derived stem cells (ADSCs) to fibroblasts and chondrocytes.

STUDY DESIGN/MATERIALS AND METHODS

After irradiation, the morphology, viability, and adenosine triphosphate (ATP) proliferation of the ADSCs were analyzed at different time intervals. The differentiation of ADSCs toward fibroblastic and chondrogenic phenotypes was supported using flow cytometry and immunofluorescence at 1- and 2-week post-irradiation.

RESULTS

More than 90% of viable cells were observed in all experimental groups, with an increase in ATP proliferation. Flow cytometry analyses and immunofluorescence demonstrated the presence of chondrogenic and fibroblastic cell surface markers at 1- and 2-week post-irradiation.

CONCLUSION

This study has demonstrated methods to induce the differentiation of ADSCs toward fibroblastic and chondrogenic phenotypes with a 660 nm diode laser. The study also proposes a future alternative method of treatment for patients with degenerative TMJ disc disorders and presents a positive prospect in the application of photobiomodulation and ADSCs in the treatment of degenerative TMJ disc. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Cone beam computed tomography findings in temporomandibular joint of chronic qat chewers: Dimensional and osteoarthritic changes

The social habit of chewing qat (also known as khat) is widely practised in East Africa and the Arabian Peninsula. It has been linked with various oro-facial conditions, including temporomandibular joint disorders (TMD). This cross-sectional, comparative study sought to investigate the effects of qat chewing on temporomandibular joint (TMJ), using cone beam computed tomography (CBCT). A total of 85 Yemeni males were included. The participants were divided into two groups: Qat chewers (QC; n = 41) and non-qat chewers (NQC; n = 44). Relevant data were obtained using a structured questionnaire and standardised clinical examination. Additionally, CBCT images of the TMJs were obtained, and then, osteoarthritic changes and TMJ dimensions were analysed. SPSS 21 was used for statistical analyses, with a significant level was set at 0.05. Compared to NQC, a significantly higher proportion of QC presented with clinical signs of TMDs. The qualitative CBCT findings revealed significantly higher osteoarthritic changes in QC than in NQC: osteophyte (51.2% vs 22.7%; P = .008), subcortical sclerosis (48.8% vs 27.3%; P = .047), articular surface flattening (46.3% vs 6.8%; P = .009) and subcortical cysts (43.9% vs 4.5%; P < .001). However, CBCT quantitative findings (condylar dimensions) did not show significant differences between the two groups. The chewing side of the QC group showed slightly more changes compared to the non-chewing side. The results demonstrate that qat chewing has detrimental effects on TMJ manifested mainly as osteoarthritic changes. Further large-scale studies are recommended.

Photobiomodulation and Stem Cell Therapy for Temporomandibular Joint Disc Disorders

Background: Temporomandibular disorder (TMD) refers to a group of disorders affecting the temporomandibular joint (TMJ) and its related muscles. The two commonly used treatment modalities for TMD are occlusal splint therapy and relaxation therapy. Neither comprises definitive treatment. Objective: The objective of this review was to report updated information on photobiomodulation and stem cells, as an alternative treatment for the degenerative TMJ disc as a part of TMJ disorders. Materials and methods: With only a few research studies reported till date, this review also proposes the mechanism of laser irradiation on inflammatory mediators to treat TMD. Results: Photobiomodulation of stem cells with and without scaffolds could be used indirectly or directly as modulation of degenerative changes of the TMJ disc. Conclusions: The need for a distinct shift of the research margin in this field of dentistry is evident, specifically regarding the application of photobiomodulation and stem cells for tissue engineering of the TMJ disc.

The Biomechanical Effect of the Sagittal Split Ramus Osteotomy on the Temporomandibular Joint: Current Perspectives on the Remodeling Spectrum

The sagittal split ramus osteotomy is a key approach for treating dentofacial deformities. Although it delivers excellent results, the sagittal split ramus osteotomy is believed to induce stress to the temporomandibular joint. Potential stress inducers could be classified as intra- and postoperative factors resulting in an inflammatory response and molecular cascades, which initiate physiological remodeling. Occasionally, this process exceeds its capacity and causes pathological remodeling, through either degenerative joint disease or condylar resorption. Hard evidence on how orthognathic surgery causes inflammation and how this inflammation is linked to the spectrum of remodeling remains scarce. Current concepts on this matter are mainly based on clinical observations and molecular mechanisms are extrapolated from fundamental research in other body parts or joints. This perspective study provides an overview of current knowledge on molecular pathways and biomechanical effects in temporomandibular joint remodeling. It provides research directions that could lead to acquiring fundamental evidence of the relation of orthognathic surgery and inflammation and its role in remodeling. Performing osteotomies in animal models and identifying inflammatory mediators as well as their effect on the joint seem promising. Patients affected by pathological remodeling can also provide samples for histological as well as molecular analysis. Individual susceptibility analysis by linking certain suspect phenotypes to genetic variation could identify the cause and molecular pathway responsible for degenerative joint disease and condylar resorption, ultimately leading to clinically applicable treatment and prevention strategies.

Effect of occlusal splint on interleukin 6, malondialdehyde and 8-hydroxydeoxyguanosine levels in the synovial fluid of patients with temporomandibular disorders

The actual role of splint therapy in preventing excessive loading of the temporomandibular joint (TMJ) is still debated. Lower intra-articular pressure levels have been measured in patients wearing occlusal splints, which may also reduce oxidative stress in the articular spaces. The aim of this study was to determine whether splint therapy reduces oxidative stress and inflammation in TMJ internal derangement patients by measuring interleukin 6 (IL-6), malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHdG) levels in the synovial fluid (SF). Twenty-four patients with a temporomandibular disorder (TMD) were included in the study. TMJ SF samples were obtained prior to arthrocentesis. Twelve patients used a 2-mm hard acrylic, maxillary stabilization-type splint for 3 months after arthrocentesis. Twelve patients had no treatment after the SF aspiration. Second SF samples were obtained from all patients at 3 months post arthrocentesis. IL-6, MDA, and 8-OHdG levels in the samples were evaluated. All patients showed a significant symptomatic improvement after treatment (P < 0.005). No statistical correlation was found between the two groups concerning pre-treatment and 3-month SF levels of MDA, 8-OHdG, and IL-6. Although splint therapy was found to be successful in eliminating clinical symptoms of TMD, the results showed no beneficial effect on inflammation and oxidative stress markers in the synovial fluid.

Mechanical stretch enhances NF-kappaB-dependent gene expression and poly(ADP-ribose) synthesis in synovial cells

Temporomandibular joint disorders (TMD) show complex symptoms associated with inflammation, pain and degeneration of the peripheral tissues including synovium. Although it is believed that excessive mechanical stress on synovium causes development of TMD, the molecular mechanism by which mechanical stress triggers TMD has still remained unclear. In order to examine the effect of mechanical stress on synoviocytes, rabbit synovial cells were cyclically stretched in vitro. The stretch efficiently increased the gene expressions of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and NF-kappaB responsive reporter gene constructs. The interruption of NF-kappaB activating pathway by inhibitors resulted in the abrogation of those expressions, indicating the pivotal role of NF-kappaB in the mechanical stretch-mediated COX-2 and iNOS expressions. In parallel, the stretch remarkably increased NO production and poly(ADP-ribose) (PAR) synthesis, suggesting that excessive amounts of NO causes DNA injury and in turn activates PAR synthesis by poly(ADP-ribose) polymerase (PARP). The inhibition of PAR synthesis by a PARP inhibitor or a radical scavenger enhanced the mechanical stretch-induced gene expressions in a NF-kappaB-independent manner, implying an involvement of PARP in the gene expression. Taken together, these results demonstrate that mechanical stress on synovial cells not only induces gene expressions of COX-2 and iNOS but also affects PAR synthesis.