Shixun Wu

The Role of Mitochondria in T-2 Toxin-Induced Human Chondrocytes Apoptosis

T-2 toxin, a mycotoxin produced by Fusarium species, has been shown to cause diverse toxic effects in animals and is also a possible pathogenic factor of Kashin–Beck disease (KBD). The role of mitochondria in KBD is recognized in our recent research. The aim of this study was to evaluate the role of mitochondria in T-2 toxin-induced human chondrocytes apoptosis to understand the pathogenesis of KBD. T-2 toxin decreased chondrocytes viabilities in concentration- and time-dependent manners. Exposure to T-2 toxin can reduce activities of mitochondrial complexes III, IV and V, ΔΨm and the cellular ATP, while intracellular ROS increased following treatment with T-2 toxin. Furthermore, mitochondrial cytochrome c release, caspase-9 and 3 activation and chondrocytes apoptosis were also obviously observed. Interestingly, Selenium (Se) can partly block T-2 toxin -induced mitochondria dysfunction, oxidative damage and chondrocytes apoptosis. These results suggest that the effect of T-2 toxin on human chondrocytes apoptosis may be mediated by a mitochondrial pathway, which is highly consistent with the chondrocytes changes in KBD.

Synthesis and characterization of selenium-chondroitin sulfate nanoparticles.

A novel selenium-chondroitin sulfate (SeCS) was synthesized by ultrasonic and dialysis method. With characterization by FTIR, XRD and TEM, the SeCS was found to form nanoparticles in distilled water through a self-aggregation progress. The SeCS nanoparticles had sizes between 30 and 200 nm with selenium entrapment efficiency of about 10.1%. The anti-toxin capacity of SeCS nanoparticles was demonstrated through MTT and apoptosis assays in vitro. Results indicated that the SeCS was less cytotoxic to chondrocytes than sodium selenite. In particular, the SeCS could obviously alleviate chondrocyte apoptosis induced by T-2 toxin compared to chondroitin sulfate. These results thus represent an advanced understanding of the properties of SeCS nanoparticles and demonstrate their exciting potential applications in therapy of Kashin-Beck disease (KBD) and osteoarthritis.

Identification of differentially expressed genes and pathways between primary osteoarthritis and endemic osteoarthritis (Kashin–Beck disease)

Objectives: Primary osteoarthritis (OA) and Kashin–Beck disease (KBD) exhibit similar clinical manifestations and common articular cartilage lesions. Revealing the pathogenetic differences between OA and KBD is helpful for differential diagnosis and may provide new insights into the pathogenesis of OA and KBD. In this study, we compared the genome-wide gene ontology (GO) and pathway expression patterns of articular cartilage derived from both OA and KBD patients. Methods: Total RNA was isolated, amplified, labelled, and hybridized using Agilent whole genome microarray analysis. Gene set enrichment analysis (GSEA) was used to identify differentially expressed genes and pathways between OA and KBD. Nine differentially expressed GO categories and 85 differentially expressed pathways were identified by this study. Results: The reactive oxygen species (ROS)-related HOUSTIS_ROS pathway and the vascular endothelial growth factor (VEGF)-related ABE_VEGFA_TARGETS_2HR pathway were significantly up-regulated in OA compared to KBD. Higher expression levels of the collagen-related COLLAGEN GO, EXTRACELLULAR_MATRIX_PART GO, and nitric oxide (NO)-related BIOCARTA_NO1_PATHWAY pathways were detected in KBD than in OA. Conclusions: ROS-induced cartilage lesions seem to be more involved in the pathogenesis of OA whereas NO-mediated chondrocyte apoptosis contributes more to the development of KBD.

Genome-Wide Pathway Association Studies of Multiple Correlated Quantitative Phenotypes Using Principle Component Analyses

Genome-wide pathway association studies provide novel insight into the biological mechanism underlying complex diseases. Current pathway association studies primarily focus on single important disease phenotype, which is sometimes insufficient to characterize the clinical manifestations of complex diseases. We present a multi-phenotypes pathway association study(MPPAS) approach using principle component analysis(PCA). In our approach, PCA is first applied to multiple correlated quantitative phenotypes for extracting a set of orthogonal phenotypic components. The extracted phenotypic components are then used for pathway association analysis instead of original quantitative phenotypes. Four statistics were proposed for PCA-based MPPAS in this study. Simulations using the real data from the HapMap project were conducted to evaluate the power and type I error rates of PCA-based MPPAS under various scenarios considering sample sizes, additive and interactive genetic effects. A real genome-wide association study data set of bone mineral density (BMD) at hip and spine were also analyzed by PCA-based MPPAS. Simulation studies illustrated the performance of PCA-based MPPAS for identifying the causal pathways underlying complex diseases. Genome-wide MPPAS of BMD detected associations between BMD and KENNY_CTNNB1_TARGETS_UP as well as LONGEVITYPATHWAY pathways in this study. We aim to provide a applicable MPPAS approach, which may help to gain deep understanding the potential biological mechanism of association results for complex diseases.

Matrix metalloproteinase-1 gene polymorphisms and periodontitis susceptibility: a meta-analysis based on 11 case-control studies.

Matrix metalloproteinase-1 has been implicated in periodontal disease, but the association between the most-studied Matrix metalloproteinase-1 1G-to-2G polymorphism and the risk of periodontal disease were reported with inconclusive results. Therefore, the aim of this study was to investigate the association between the Matrix metalloproteinase-1 1G-to-2G polymorphism and periodontal disease. Electronic databases search yielded 11 studies with 1447 patients and 1710 control subjects evaluated the association of the polymorphisms of Matrix metalloproteinase-1 1G-to-2G and periodontitis risk were brought into this study. The association was evaluated by odds ratio (OR) and its 95% confidence interval (CI). The overall results showed that the variant genotypes were associated with a significantly increased risk of periodontitis (OR=1.45, 95% CI=1.02-1.26 for 2G/2G vs 1G/1G, and OR=2.27, 95% CI=1.22-4.23 for 2G/2G vs 1G/2G+1G/1G). In the stratified analyses, there was a significantly increased risk for the studies of periodontitis (OR=1.59, 95% CI=1.15-2.21 for 2G/2G vs 1G/1G; OR=3.48, 95% CI=1.39-8.71 for 2G/2G vs 1G/2G+1G/1G), which remained for the studies of Asian populations. And there was a significantly increased risk of severe periodontitis (OR=2.15, 95% CI=1.35-3.43 for 2G/2G vs 1G/1G; OR=2.86, 95% CI=1.31-2.64 for 2G/2G vs 1G/2G+1G/1G; OR=1.6, 95% CI=1.12-2.39 for 1G/2G+2G/2G vs 1G/1G; OR=1.61, 95% CI=1.28-2.03 for 2G allele vs 1G allele). The current study demonstrated that the Matrix metalloproteinase-1-1607 1G-to-2G polymorphism was associated with susceptibility to periodontitis, apparently, severe periodontitis.

Disordered glycometabolism involved in pathogenesis of Kashin-Beck disease, an endemic osteoarthritis in China.

Kashin-Beck disease (KBD) is a chronic endemic osteoarthritis in China. Previous studies have suggested a role of metabolic dysfunction in causation of this disease. In this investigation, the metabolomics approach and cell experiments were used to discover the metabolic changes and their effects on KBD chondrocytes. Nuclear magnetic resonance ((1)H NMR) spectroscopy was used to examine serum samples from both the KBD patients and normal controls. The pattern recognition multivariate analysis (OSC-PLS) and quantitative analysis (QMTLS iterator) revealed altered glycometabolism in KBD, with increased glucose and decreased lactate and citrate levels. IPA biological analysis showed the centric location of glucose in the metabolic network. Massive glycogen deposits in chondrocytes and increased uptake of glucose by chondrocytes further confirmed disordered glycometabolism in KBD. An in vitro study showed the effects of disordered glycometabolism in chondrocytes. When chondrocytes were treated with high glucose, expression of type II collagen and aggrecan were decreased, while TNF-α expression, the level of cellular reactive oxygen species and cell apoptosis rates all were increased. Therefore, our results demonstrated that disordered glycometabolism in patients with KBD was linked to the damage of chondrocytes. This may provide a new basis for understanding the pathogenesis of KBD.

Expression profile analysis of mycotoxin-related genes in cartilage with endemic osteochondropathy kashin-beck disease

BackgroundKashin-Beck Disease (KBD) is an endemic osteochondropathy. Mycotoxins are believed to play an important role in the pathogenesis of KBD. Because the molecular mechanism of mycotoxin-induced cartilage lesions remains unclear, there is not effective treatment for KBD now. To identify key genes involved in the mycotoxin-induced cartilage lesions, we compared the expression profiles of mycotoxin-related genes (MRG) between KBD cartilage and healthy cartilage.MethodsTotal RNA was isolated from cartilage samples, following by being amplified, labeled and hybridized to Agilent human whole genome microarray chip. qRT-PCR was conducted to validate the microarray data. 1,167 MRG were derived from the environmentally related genomic database Toxicogenomics. The microarray data of MRG was subjected to single gene and gene ontology (GO) expression analysis for identifying differently expressed genes and GO.ResultsWe identified 7 up-regulated MRG and 2 down-regulated MRG in KBD cartilage, involved in collagen, apoptosis, metabolism and growth & development. GO expression analysis found that 4 apoptosis-related GO and 5 growth & development-related GO were significantly up-regulated in KBD cartilage.ConclusionsBased on the results of previous and our studies, we suggest that mycotoxins might contribute to the development of KBD through dysfunction of MRG involved in collagen, apoptosis and growth & development in cartilage.

MALDI-TOF-MS serum protein profiling for developing diagnostic models and identifying serum markers for discogenic low back pain

BackgroundThe identification of the cause of chronic low back pain (CLBP) represents a great challenge to orthopedists due to the controversy over the diagnosis of discogenic low back pain (DLBP) and the existence of a number of cases of CLBP of unknown origin. This study aimed to develop diagnostic models to distinguish DLBP from other forms of CLBP and to identify serum biomarkers for DLBP.MethodsSerum samples were collected from patients with DLBP, chronic lumbar disc herniation (LDH), or CLBP of unknown origin, and healthy controls (N), and randomly divided into a training set (n = 30) and a blind test set (n = 30). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry was performed for protein profiling of these samples. After the discriminative ability of two most significantly differential peaks from each two groups was assessed using scatter plots, classification models were developed using differential peptide peaks to evaluate their diagnostic accuracy. The identity of peptides corresponding to three representative differential peaks was analyzed.ResultsThe fewest statistically significant differential peaks were identified between DLBP and CLBP (3), followed by CLBP vs. N (5), DLBP vs. N (9), LDH vs. CLBP (20), DLBP vs. LDH (23), and LDH vs. N (43). The discriminative ability of two most significantly differential peaks was poor in classifying DLBP vs. CLBP but good in classifying DLBP vs. LDH. The accuracy of models for classification of DLBP vs. CLBP was not very high in the blind test (forecasting ability, 67.24%; sensitivity, 70%), although a higher accuracy was observed for classification of DLBP vs. LDH and LDH vs. N (forecasting abilities, ~90%; sensitivities, >90%). A further investigation of three representative differential peaks led to the identification of two peaks as peptides of complement C3, and one peak as a human fibrinogen peptide.ConclusionsOur findings benefit not only the diagnosis of CLBP but also the understanding of the differences between different forms of DLBP. The ability to distinguish between different causes of CLBP and the identification of serum biomarkers may be of great value to diagnose different causes of DLBP and predict treatment efficacy.