Abnormal expression of Col X, PTHrP, TGF-beta, bFGF, and VEGF in cartilage with Kashin-Beck disease

Selenium Deficiency Can Promote the Expression of VEGF and Inflammatory Factors in Cartilage Differentiation and Mediates Cartilage Injury

Selenium plays a crucial role as a micronutrient, primarily exerting its biological functions through selenoproteins. It has been established that selenium deficiency adversely impacts cartilage development, leading to alterations in chondrocyte function. In regions with low selenium intake, endemic osteochondrosis has been documented, characterized by compromised growth plate and articular cartilage formation. Vascular endothelial growth factor (VEGF) stands out as a pivotal angiogenic factor, with elevated levels contributing significantly to vascular invasion into chondrocytes. This VEGF-mediated invasion serves as a key signal, prompting morphological changes in the growth plate and initiating cartilage remodeling. In animal models, the selenium deficiency group exhibited heightened levels of the cartilage damage marker matrix metalloproteinases 13 (MMP13). This resulted in articular cartilage degeneration, accompanied by a substantial increase in VEGF expression within the growth plate and articular cartilage, as compared to the normal group. In a chondrogenic progenitor cell (CPC) differentiation model, insufficient selenium induced chondrocyte damage and upregulated inflammatory factors such as inducible NO synthase (iNOS) and cyclooxygenase-2 (COX2). The selenium-deficient groups showed elevated expressions of VEGF, VEGFR2, MMP13, Collagen X, and Angiopoietin 1, accelerating the degradation of the extracellular matrix (ECM), which further promoted the development of cartilage-related diseases. Taken together, these findings provide novel insights for a better understanding of the role of low selenium in cartilage degeneration and angiogenesis. They shed light on the intricate influence of low selenium levels on the development of articular cartilage, emphasizing the interconnected pathways and processes involved.

Increased FGFR3 is involved in T-2 toxin-induced lesions of hypertrophic cartilage associated with endemic osteoarthritis

This study evaluated the effect of fibroblast growth factor receptor 3 (FGFR3) on damaged hypertrophic chondrocytes of Kashin-Beck disease (KBD). Immunohistochemical staining was used to evaluate FGFR3 expression in growth plates from KBD rat models and engineered cartilage. In vitro study, hypertrophic chondrocytes were pretreated by FGFR3 binding inhibitor (BGJ398) for 24 h before incubation at different T-2 toxin concentrations. Differentiation -related genes (Runx2, Sox9, and Col Ⅹ) and ECM degradation -related genes (MMP-13, Col Ⅱ) in the hypertrophic chondrocytes were analyzed using RT-PCR, and the corresponding proteins were analyzed using western blotting. Hypertrophic chondrocytes death was detected by the Annexin V/PI double staining assay. The integrated optical density of FGFR3 staining was increased in knee cartilage of rats and engineered cartilage treated with T-2 toxin. Both protein and mRNA levels of Runx2, Sox9, Col Ⅱ, and Col Ⅹ were decreased in a dose-dependent manner when exposed to the T-2 toxin and significantly upregulated by 1 μM BGJ398. The expression of MMP-1, MMP-9, and MMP-13 increased in a dose-dependent manner when exposed to T-2 toxin and significantly reduced by 1 μM BGJ398. 1 μM BGJ398 could prevent early apoptosis and necrosis induced by the T-2 toxin. Inhibiting the FGFR3 signal could alleviate extracellular matrix degradation, abnormal chondrocytes differentiation, and excessive cell death in T-2 toxin-induced hypertrophic chondrocytes.

MMP-10 Deficiency Effects Differentiation and Death of Chondrocytes Associated with Endochondral Osteogenesis in an Endemic Osteoarthritis

OBJECTIVE

The objective of this study was to determine the matrix metalloproteinase-10 (MMP-10) expression pattern and to assess how it contributes to endochondral osteogenesis in Kashin-Beck disease (KBD).

DESIGN

The cartilages of KBD patients, Sprague-Dawley rats fed with selenium (Se)-deficient diet and/or T-2 toxin, and ATDC5 cells were used in this study. ATDC5 cells were induced into hypertrophic chondrocytes using a 1% insulin-transferrin-selenium (ITS) culture medium for 21 days. The expressions of MMP-10 in the cartilages were visualized by immunohistochemistry. The messenger RNA (mRNA) and protein expression levels were determined by real-time polymerase chain reaction (RT-PCR) and Western blotting. MMP-10 short hairpin RNA (shRNA) was transfected into hypertrophic chondrocytes to knock down the gene expression of MMP-10. Meanwhile, the cell death of MMP-10-knockdown chondrocyte was detected using flow cytometry.

RESULTS

The expression of MMP-10 was decreased in the growth plates of children with KBD. A decreased expression of MMP-10 also was observed in the growth plates of rats fed with an Se-deficient diet and/or T-2 toxin exposure. The mRNA and protein expression levels of MMP-10 increased during the chondrogenic differentiation of ATDC5 cells. MMP-10 knockdown in hypertrophic chondrocytes significantly decreased the gene and protein expression of collagen type II (Col II), Col X, Runx2, and MMP-13. Besides, the percentage of cell apoptosis was significantly increased after MMP-10 knockdown in hypertrophic chondrocytes.

CONCLUSION

MMP-10 deficiency disrupts chondrocyte terminal differentiation and induces the chondrocyte's death, which impairs endochondral osteogenesis in the pathogenesis of KBD.

Genetic Variants and Protein Alterations of Selenium- and T-2 Toxin-Responsive Genes Are Associated With Chondrocytic Damage in Endemic Osteoarthropathy

The mechanism of environmental factors in Kashin–Beck disease (KBD) remains unknown. We aimed to identify single nucleotide polymorphisms (SNPs) and protein alterations of selenium- and T-2 toxin–responsive genes to provide new evidence of chondrocytic damage in KBD. This study sampled the cubital venous blood of 258 subjects including 129 sex-matched KBD patients and 129 healthy controls for SNP detection. We applied an additive model, a dominant model, and a recessive model to identify significant SNPs. We then used the Comparative Toxicogenomics Database (CTD) to select selenium- and T-2 toxin–responsive genes with the candidate SNP loci. Finally, immunohistochemistry was applied to verify the protein expression of candidate genes in knee cartilage obtained from 15 subjects including 5 KBD, 5 osteoarthritis (OA), and 5 healthy controls. Forty-nine SNPs were genotyped in the current study. The C allele of rs6494629 was less frequent in KBD than in the controls (OR = 0.63, p = 0.011). Based on the CTD database, PPARG, ADAM12, IL6, SMAD3, and TIMP2 were identified to interact with selenium, sodium selenite, and T-2 toxin. KBD was found to be significantly associated with rs12629751 of PPARG (additive model: OR = 0.46, p = 0.012; dominant model: OR = 0.45, p = 0.049; recessive model: OR = 0.18, p = 0.018), rs1871054 of ADAM12 (dominant model: OR = 2.19, p = 0.022), rs1800796 of IL6 (dominant model: OR = 0.30, p = 0.003), rs6494629 of SMAD3 (additive model: OR = 0.65, p = 0.019; dominant model: OR = 0.52, p = 0.012), and rs4789936 of TIMP2 (recessive model: OR = 5.90, p = 0.024). Immunohistochemistry verified significantly upregulated PPARG, ADAM12, SMAD3, and TIMP2 in KBD compared with OA and normal controls (p < 0.05). Genetic polymorphisms of PPARG, ADAM12, SMAD3, and TIMP2 may contribute to the risk of KBD. These genes could promote the pathogenesis of KBD by disturbing ECM homeostasis.

An integrative analysis of DNA methylation and transcriptome showed the dysfunction of MAPK pathway was involved in the damage of human chondrocyte induced by T-2 toxin

Background

T-2 toxin is thought to induce the growth plate and articular cartilage damage of Kashin-Beck disease (KBD), an endemic osteochondropathy in China. This study aims to explore the potential underlying mechanism of such toxic effects by integrating DNA methylation and gene expression profiles.

Methods

In this study, C28/I2 chondrocytes were treated with T-2 toxin (5 ng/mL) for 24 h and 72 h. Global DNA methylation level of chondrocyte was tested by Enzyme-Linked Immuno Sorbent Assay. Genome-wide DNA methylation and expression profiles were detected using Illumina Infinium HumanMethylation850 BeadChip and RNA-seq technique, respectively. Differentially methylated genes (DMGs) and differentially expressed genes (DEGs) were identified mainly for two stages including 24 h group versus Control group and 72 h group versus 24 h group. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed by Metascape. DMGs and DEGs were further validated by Sequenom MassARRAY system and quantitative real-time polymerase chain reaction.

Results

The global DNA methylation levels of chondrocytes exposed to T-2 toxin were significantly increased (P < 0.05). For 24 h group versus Control group (24 VS C), 189 DEGs and 590 DMGs were identified, and 4 of them were overlapping. For 72 h group versus 24 h group (72 VS 24), 1671 DEGs and 637 DMGs were identified, and 45 of them were overlapping. The enrichment analysis results of DMGs and DEGs both showed that MAPK was the one of the mainly involved signaling pathways in the regulation of chondrocytes after T-2 toxin exposure (DEGs: P_24VSc = 1.62 × 10^− 7; P_72VS24 = 1.20 × 10^− 7; DMGs: P_24VSc = 0.0056; P_72VS24 = 3.80 × 10^− 5).

Conclusions

The findings depicted a landscape of genomic methylation and transcriptome changes of chondrocytes after T-2 toxin exposure and suggested that dysfunction of MAPK pathway may play important roles in the chondrocytes damage induced by T-2 toxin, which could provide new clues for understanding the potential biological mechanism of KBD cartilage damage induced by T-2 toxin.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12860-021-00404-3.

Transforming growth factor-β receptors mediates matrix degradation and abnormal hypertrophy in T-2 toxin-induced hypertrophic chondrocytes

This study investigated whether transforming growth factor-β receptor I (TGF-βRI) and TGF-βRII mediate matrix degradation and abnormal hypertrophy in T-2 toxin-induced hypertrophic chondrocytes. Hypertrophic chondrocytes were exposed to TGF-βRI and TGF-βRII binding inhibitor (GW788388) for 24 h prior to exposure to different concentrations of T-2 toxin (0, 10, 25, and 50 ng/mL for 48 h). Hypertrophic chondrocytes were assessed based on the expression of matrix-degrading and terminal differentiation-related genes and cell viability. Matrix metalloproteinases (MMPs, MMP-13, MMP-1, and MMP-9) were reduced in the GW788388+T-2 toxin group compared to the T-2 toxin group. The expression of terminal differentiation-related genes (MMP-2, MMP-10, and collagen X) was increased in hypertrophic chondrocytes in the inhibited groups compared to that in the T-2 toxin group. The survival rate of chondrocytes decreased significantly in a dose-dependent manner. GW788388 did not significantly block the reduced cell viability in hypertrophic chondrocytes exposed to T-2 toxin. The upregulated expression of TGF-βRI and TGF-βRII mediates the abnormal chondrocyte hypertrophy and extracellular matrix degeneration observed in T-2 toxin-induced hypertrophic chondrocytes.

T-2 toxin induces articular cartilage damage by increasing the expression of MMP-13 via the TGF-β receptor pathway

T-2 toxin pre-disposes individuals to osteoarthritis, Kashin-Beck disease (KBD). The major pathological change associated with KBD is the degradation of the articular cartilage matrix. Herein, we investigated the key molecules that regulate T-2 toxin-mediated cartilage degradation. Potential KBD treatments were also investigated. Sprague Dawley rats were divided into the T-2 toxin group and the control group. The T-2 toxin group received 100 ng/g BW/day, whereas the control group received a similar dose of PBS. The expression of matrix metalloproteinase-13 (MMP-13) and TGF-β receptor I/II (TGF-βRI/II) was analyzed using immunohistochemical staining. C28/I2 chondrocytes were exposed to TGF-βRI/II binding inhibitor (GW788388) for 24 h before incubation in different T-2 toxin concentrations (0, 6, 12, and 24 ng/mL for 72 h). The expression of mRNA for TGF-βRI/II, MMP-13 and proteins for MMP-13, and Smad-2 in chondrocytes were analyzed using RT-PCR and western blot, respectively. Safranin O staining revealed that T-2 toxin treatment modulated the expression of articular cartilage matrix. On the other hand, T-2 toxin treatment sharply increased the expression of MMP-13, TGF-βRI, and TGF-βRII in the rat cartilages. Interestingly, blocking the TGF-βRs-smad 2 signaling pathway using GW788388 abrogated the effect of T-2 toxin on upregulating MMP-13 expression. The expression of MMP-13 in chondrocytes induced with T-2 toxin is regulated via the TGF-βRs signaling pathway. As such, inhibiting the expression of TGF-βRs is a potential KBD treatment.

Identification of HIF-1α/VEGFA signaling pathway and transcription factors in Kashin-Beck disease by integrated bioinformatics analysis

Kashin-Beck disease (KBD) is a chronic and endemic osteoarthropathy. The pathogenesis of KBD has yet to be fully elucidated, although previous studies have shown that its etiology may be associated with low selenium abundance and high exposure to mycotoxins, such as T-2 toxin. In the present study, the Comparative Toxicogenomics Database was used to identify key genes associated with KBD, T-2 toxin and selenium. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to identify the biological processes and pathways that key genes may be associated with. By searching the Search Tool for the Retrieval of Interacting Genes database and the Molecular Complex Detection plug-in with Cytoscape, it was possible to construct a KBD-associated protein-protein interaction (PPI) network, and screen the core modules and genes. Western blot analysis was subsequently used to verify the expression levels of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor A (VEGFA), two components that are associated with the HIF-1 signaling pathway in KBD disease. Via this approach, a total of 301 key genes were identified that were associated with KBD, T-2 toxin and selenium. The results of the GO and KEGG enrichment analyses demonstrated that these key genes were mainly involved in the process of apoptosis. Previous studies have demonstrated that excessive apoptosis of chondrocytes plays a crucial role in the pathophysiology of KBD, and that HIF-1α has an important role in chondrocyte apoptosis; therefore, the present study was focused on the expression level of HIF-1α in KBD. By analyzing the PPI network constructed from the key genes, a total of 10 core genes were obtained that may be associated with KBD. The results of western blotting experiments revealed that, after treating chondrocytes with different concentrations of T-2 toxin, the expression levels of HIF-1α and VEGFA were markedly downregulated. The iRegulon plug-in for Cytoscape was used to predict the transcription factors that may regulate HIF-1α and VEGFA in the HIF-1 signaling pathway. Using this approach, 10 core genes and 15 transcription factors were obtained. These results may help to clarify the pathogenesis of KBD, thereby providing further avenues for the therapeutic treatment of KBD.

The integrative analysis of DNA methylation and mRNA expression profiles confirmed the role of selenocompound metabolism pathway in Kashin-Beck disease

Kashin-Beck disease (KBD) is an endemic chronic osteochondropathy. The etiology of KBD remains unknown. In this study, we conducted an integrative analysis of genome-wide DNA methylation and mRNA expression profiles between KBD and normal controls to identify novel candidate genes and pathways for KBD. Articular cartilage samples from 17 grade III KBD patients and 17 healthy controls were used in this study. DNA methylation profiling of knee cartilage and mRNA expression profile data were obtained from our previous studies. InCroMAP was performed to integrative analysis of genome-wide DNA methylation profiles and mRNA expression profiles. Gene ontology (GO) enrichment analysis was conducted by online DAVID 6.7. The quantitative real-time polymerase chain reaction (qPCR), Western blot, immunohistochemistry (IHC), and lentiviral vector transfection were used to validate one of the identified pathways. We identified 298 common genes (such as COL4A1, HOXA13, TNFAIP6 and TGFBI), 36 GO terms (including collagen function, skeletal system development, growth factor), and 32 KEGG pathways associated with KBD (including Selenocompound metabolism pathway, PI3K-Akt signaling pathway, and TGF-beta signaling pathway). Our results suggest the dysfunction of many genes and pathways implicated in the pathogenesis of KBD, most importantly, both the integrative analysis and in vitro study in KBD cartilage highlighted the importance of selenocompound metabolism pathway in the pathogenesis of KBD for the first time.

Effects of methylation of deiodinase 3 gene on gene expression and severity of Kashin-Beck disease

Kashin-Beck disease (KBD) is a complex endemic osteoarthropathy, which mainly occurs in the northeast to southwest China. Iodothyronine deiodinases 3 (DIO3) is one of the selenoproteins, which is closely related to bone metabolism and unclear to KBD. This study aims to investigate the role and associated mechanisms of methylation and expression of DIO3 with disease severity in patients with KBD. We performed a bioinformatics analysis first to identify the biological mechanisms involved in selenoproteins. The methylation status of the DIO3 gene and DIO3 gene expression, as well as DIO3-related regulatory genes in patients with KBD, were analyzed. We found that 15 CpG sites of six selenoproteins were hypomethylated with 5-azacytidine treatment. DIO3 hypermethylation was associated with an increased risk of KBD and may lead to downregulation of DIO3 gene expression as well as be an indicator of the severity of KBD, which may provide a new insight for gene-environment correlations and interactions in etiology and pathogenesis of KBD.

Expression and localization of the small proteoglycans decorin and biglycan in articular cartilage of Kashin-Beck disease and rats induced by T-2 toxin and selenium deficiency

Kashin-Beck disease (KBD) is an endemic degenerative osteoarthropathy of uncertain etiology. Our study sought to identify a correlation between small proteoglycans decorin and biglycan expression and Kashin-Beck Disease. Immunohistochemistry was used to assess the decorin and biglycan levels in cartilage specimens from both child KBD patients, and rats fed with T-2 toxin under a selenium-deficient condition. Real-time PCR and Western blot were used to assess mRNA and protein levels of decorin and biglycan in rat cartilages, as well as in C28/I2 chondrocytes stimulated by T-2 toxin and selenium in vitro. The result showed that decorin was reduced in all zones of KBD articular cartilage, while the expression of biglycan was prominently increased in KBD cartilage samples. Increased expression of biglycan and reduced expression of decorin were observed at mRNA and protein levels in the cartilage of rats fed with T-2 toxin and selenium- deficiency plus T-2 toxin diet, when compared with the normal diet group. Moreover, In vitro stimulation of C28/I2 cells with T-2 toxin resulted in an upregulation of biglycan and downregulation of decorin, T-2 toxin induction of biglycan and decorin levels were partly rescued by selenium supplement. This study highlights the focal nature of the degenerative changes that occur in KBD cartilage and may suggest that the altered expression pattern of decorin and biglycan have an important role in the onset and pathogenesis of KBD.

Basic fibroblast growth factor and agarose gel promote ​the ability of immune privilege of allogeneic cartilage transplantation in rats

Objective

Allogeneic cartilage transplantation is used to treat severe osteochondral defects or cartilaginous injury. However, acute immune rejection has been a key problem interfering with graft healing.

Methods

Full-thickness osteochondral defects were performed in Sprague Dawley rats. The allograft implants were set into the defect region. Blood and spleen samples from Postoperative Day 3 onward were collected for inflammatory cell analysis, including analysis of monocytes, natural killer cells, CD4⁺CD25⁺Foxp3⁺ regulatory T cells, CD4⁺ T cells, and CD8⁺ T cells. Gross observation and histologic staining (hematoxylin and eosin, toluidine blue) were carried out at the same time point to assess the repair effect of the cartilage graft and the degree of immune rejection.

Results

Treatment with basic fibroblast growth factor, agarose gel, and allogeneic cartilage was similar to that of the autologous group. The percentage of monocytes in allografts was at a higher level in the spleen and blood; the frequency of CD4⁺ T cells in the allogeneic group was higher than in the autologous group and the other agarose groups at 6 weeks after transplantation. The number of regulatory T cells in the autograft was increased from Postoperative Week 1; similar results were observed in groups containing basic fibroblast growth factor beginning at Postoperative Week 3.

Conclusions

Allogeneic cartilage transplantation induces acute immune rejection, which compromises the validity of the implant. The combination of basic fibroblast growth factor and agarose gel facilitates the goal of immune privilege and promotes the success of the allograft tissues.

The translational potential of this article

This study investigated the combination of basic fibroblast growth factor (bFGF) and agarose gel facilitates promotes the success of the allograft tissues transplantation. This work may help clinicians find a new way to repair articular cartilage damage. This will affect the treatment of articular cartilage movement injuries and arthritis.

Differential gene expression in articular cartilage between rheumatoid arthritis and endemic Kashin-Beck disease

Kashin-beck disease (KBD) is endemic chronic osteoarthrosis and its pathogenesis is still unclear. The present study aimed to explore differential gene expression in articular cartilage between patients with rheumatoid arthritis (RA) and KBD. Articular cartilages were collected from KBD and RA patients, and differentially expressed genes (DEGs) were analyzed by RNA-seq. The signaling pathway and biological process (BP) of the DEGs were identified by enrichment analysis. The protein-protein interaction (PPI) network of DEGs and the key genes of KBD were identified by network analysis with STRING and cytoscape software. We identified 167 immune-related DEGs in articular cartilage samples from KBD patients compared with RA. The up-regulation of MAPK signaling pathway and the down-regulation of signaling pathways such as toll-like receptor, janus kinase-signal transducers and activators of transcription, leukocyte migration, T-cell receptor and chemokine, and antigen processing and presentation were involved in KBD. We identified 137 genes nodes related with immune and mapped the PPI network diagram. BP analysis revealed that immune response, calcium ion homeostasis, blood vessel morphogenesis, inflammatory response, lymphocyte proliferation, and MAPK activation were involved in KBD. In conclusion, gene expression profiling can be used to identify the different mechanism of pathogenesis between KBD and RA.

Biological Analysis of Gene Expression and Clinical Variables Suggest FZD1 as a Novel Biomarker for Patients with Kashin-Beck Disease, an Endemic Osteoarthritis in China

Clinical variables contribute to the severity of Kashin-Beck disease (KBD). However, it is unclear if there is a correlation between gene expression and clinical variables. Peripheral blood samples were collected from 100 patients with KBD and 100 healthy controls from KBD-endemic areas to identify differentially expressed genes in KBD. Correlation analysis and multiple logistic regression analysis were performed using gene expression and clinical parameters. Immunohistochemistry (IHC) was used to detect the expression of related proteins in articular cartilage tissues. Thirty-nine differentially expressed genes were identified in patients with KBD. Nine differentially expressed genes were correlated with the metacarpal length/metacarpal breadth index. FZD1 was identified as having statistical significance in establishing the regression model of clinical parameters and gene expression. FZD1 expression levels were remarkably reduced in patients with KBD. Our results indicate that FZD1 could be involved in the pathological process of phalanges tuberositas and brachydactylia and may provide new insight into the pathogenesis of articular cartilage destruction observed in patients with KBD.

Changes in osteogenic gene expression in hypertrophic chondrocytes induced by SIN-1

The molecular mechanisms underlying osteoarthritis (OA) and Kashin-Beck disease (KBD) remain poorly understood. Hypertrophic chondrocytes serve an important role in the development of both OA and KBD, whereas oxidative stress can contribute to the pathological progression of cartilage damage. Therefore, the aim of the present study was to detect altered expression of osteogenesis-related genes in hypertrophic chondrocytes, following treatment with 3-morpholinosydnonimine (SIN-1). ATDC5 cells were induced to develop into hypertrophic chondrocytes via Insulin-Transferrin-Selenium. The appropriate concentration and time of SIN-1 treatment was determined via MTT assay. Following hypertrophic chondrocyte stimulation with SIN-1, a liquid chip was analyzed using a polymerase chain reaction (PCR) array. Reverse transcription-quantitative PCR was conducted on individual genes to validate the array-based data. Analyses of protein-protein interactions, gene ontology functions and Kyoto Encyclopedia of Genes and Genomes pathway enrichment of the differentially expressed genes were also performed. A total of 6 upregulated and 34 downregulated genes were identified, including the mothers against decapentaplegic homolog (Smad) family (Smad1-4), bone morphogenetic proteins and their receptors (Bmp2, Bmp3, Bmpr1α and Bmpr1β), and matrix metalloproteinases (MMP2,−9 and−10). These genes are associated with collagen biology, transcriptional control, skeletal development, bone mineral metabolism, and cell adhesion. SIN-1 induced death of hypertrophic chondrocytes likely through TGF-β/Smad or BMP/Smad pathways. Oxidative-stress-dependent induction of abnormal gene expression may be associated with chondronecrosis in the cartilage of patients with OA or KBD.

Integrating genome-wide DNA methylation and mRNA expression profiles identified different molecular features between Kashin-Beck disease and primary osteoarthritis

Background

Kashin-Beck disease (KBD) is an endemic osteochondropathy of unknown etiology. Osteoarthritis (OA) is a form of degenerative joint disease sharing similar clinical manifestations and pathological changes to articular cartilage with KBD.

Methods

A genome-wide DNA methylation profile of articular cartilage from five KBD patients and five OA patients was first performed using the Illumina Infinium HumanMethylation450 BeadChip. Together with a previous gene expression profiling dataset comparing KBD cartilage with OA cartilage, an integrative pathway enrichment analysis of the genome-wide DNA methylation and the mRNA expression profiles conducted in articular cartilage was performed by InCroMAP software.

Results

We identified 241 common genes altered in both the DNA methylation profile and the mRNA expression profile of articular cartilage of KBD versus OA, including CHST13 (NM_152889, fold-change = 0.5979, P_methy = 0.0430), TGFBR1 (NM_004612, fold-change = 2.077, P_methy = 0.0430), TGFBR2 (NM_001024847, fold-change = 1.543, P_methy = 0.037), TGFBR3 (NM_001276, fold-change = 0.4515, P_methy = 6.04 × 10⁻⁴), and ADAM12 (NM_021641, fold-change = 1.9768, P_methy = 0.0178). Integrative pathway enrichment analysis identified 19 significant KEGG pathways, including mTOR signaling (P = 0.0301), glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulfate (P = 0.0391), glycosaminoglycan biosynthesis-keratan sulfate (P = 0.0278), and PI3K-Akt signaling (P = 0.0243).

Conclusion

This study identified different molecular features between Kashin-Beck disease and primary osteoarthritis and provided novel clues for clarifying the pathogenetic differences between KBD and OA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1531-1) contains supplementary material, which is available to authorized users.

TGF-β1/Smad3 Signaling Pathway Mediates T-2 Toxin-Induced Decrease of Type II Collagen in Cultured Rat Chondrocytes

T-2 toxin can cause damage to the articular cartilage, but the molecular mechanism remains unclear. By employing the culture of rat chondrocytes, we investigated the effect of the TGF-β1/Smad3 signaling pathway on the damage to chondrocytes induced by T-2 toxin. It was found that T-2 toxin could reduce cell viability and increased the number of apoptotic cells when compared with the control group. After the addition of the T-2 toxin, the production of type II collagen was reduced at mRNA and protein levels, while the levels of TGF-β1, Smad3, ALK5, and MMP13 were upregulated. The production of the P-Smad3 protein was also increased. Inhibitors of TGF-β1 and Smad3 were able to reverse the effect of the T-2 toxin on the protein level of above-mentioned signaling molecules. The T-2 toxin could promote the level of MMP13 via the stimulation of TGF-β1 signaling in chondrocytes, resulting in the downregulation of type II collagen and chondrocyte damage. Smad3 may be involved in the degradation of type II collagen, but the Smad3 has no connection with the regulation of MMP13 level. This study provides a new clue to elucidate the mechanism of T-2 toxin-induced chondrocyte damage.

The efficacy and safety of intra-articular injection of hyaluronic acid in the knee and physical therapy agents to treat Kashin-Beck disease: A prospective interventional study

The aim of the present study was to determine whether hyaluronic acid (HA) or physical therapy agents (PTA) can improve functional parameters in patients with knee Kashin-Beck disease (KBD). For 2 years, patients (n=55) were treated with HA weekly for 5 weeks, then received 6th and 7th injections on the 3rd and 6th month, respectively, for 7 injections in total. Patients (n=53) were treated with PTA five times a week for 3 weeks every month for 6 months. The patients were evaluated with the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the visual analog pain scale (VAS). Trial registration, ChiCTR-TRC-12002189 (http://www.chictr.org/). During the study, following treatment interruption, pain increased in the PTA group (from a mean value of 85.7±83.8 mm at month 12 to 145.2±128.8 mm at month 18 and 201.3±150.5 mm at month 24), while it remained stable in the HA group (from a mean value of 80.7±70.6 mm at month 12 to 90.1±95.2 mm at month 18 and 82.6±85.3 mm at month 24), with a statistically significant difference in favor of HA at month 18 (P<0.05) and month 24 (P<0.05). Joint stiffness, physical function and total WOMAC showed the same trend as pain. The global efficacy judgments by the patients and the investigators showed a statistically significant difference in favor of HA at month 18 (P<0.05) and month 24 (P<0.05). In conclusion, although all the patients improved in terms of pain and function, HA was superior to PTA alone for pain relief and lasting effect.

The potential biochemical markers of Kashin-Beck disease: a meta-analysis

OBJECTIVE

The objective of this study is to explore the cytokines in serum, synovial fluid as potential biomarkers of Kashin-Beck disease (KBD) and to further understand the role of these cytokines in the pathogenesis of KBD.

METHODS

A systematic electronic database search was performed from inception up to 15 March 2015. Meta-analysis was performed for cytokines more than one repetition in studies with available data. The effect size was summarized as standardized mean difference (SMD) with 95% confidence intervals (CIs) by a random effect model.

RESULTS

A total of 18 articles were included. The pooled standardized mean differences showed the serum levels of tumor necrosis factor alpha (2.72, 95% CI: 1.8 5-3.59), interleukin-1 beta (1.21, 95% CI: 0.6 1-1.80), and nitric oxide (2.60, 95% CI: 1.5 2-3.68) were significantly higher in adult KBD patients compared with that in healthy controls.

CONCLUSIONS

There was explicit evidence showing that the tumor necrosis factor alpha, interleukin-1 beta and nitric oxide were closely related to the presence of KBD, and these cytokines played a vital role in the pathogenesis of KBD.

Exome sequencing identified FGF12 as a novel candidate gene for Kashin-Beck disease

The objective of this study was to identify novel causal genes involved in the pathogenesis of Kashin-Beck disease (KBD). A representative grade III KBD sib pair with serious skeletal growth and development failure was subjected to exome sequencing using the Illumina Hiseq2000 platform. The detected gene mutations were then filtered against the data of 1000 Genome Project, dbSNP database, and BGI inhouse database, and replicated by a genome-wide association study (GWAS) of KBD. Ninety grade II or III KBD patients with extreme KBD phenotypes and 1627 healthy controls were enrolled in the GWAS. Affymetrix Genome-Wide Human SNP Array 6.0 was applied for genotyping. PLINK software was used for association analysis. We identified a novel 106T>C at the 3'UTR of the FGF12 gene, which has not been reported by now. Sequence alignment observed high conversation at the mutated 3'UTR+106T>C locus across various vertebrates. In the GWAS of KBD, we detected nine SNPs of the FGF12 gene showing association evidence (P value < 0.05) with KBD. The most significant association signal was observed at rs1847340 (P value = 1.90 × 10(-5)). This study suggests that FGF12 was a susceptibility gene of KBD. Our results provide novel clues for revealing the pathogenesis of KBD and the biological function of FGF12.

Altered proteolytic activity and expression of MMPs and aggrecanases and their inhibitors in Kashin-Beck disease

Kashin-Beck disease (KBD) is a chronic, deforming endemic osteoarticular disease with altered metabolism of the cartilage matrix. Matrix metalloproteinases (MMPs), aggrecanases (ATAMTSs), and their inhibitors (TIMPs) play important roles in cartilage formation and matrix degradation. This study investigated these proteases and inhibitors in young KBD cartilage. The percentages of chondrocytes staining for MMP-1/-13 and MMP-generated DIPEN neoepitope, aggrecanase-generated ITEGE neoepitope in aggrecan in KBD patients were significantly higher than in controls. However, TIMP-1 was significantly less numerous than in controls in the superficial and middle zones of KBD samples, the percentage of chondrocytes staining for the TIMP-2 was significantly higher than in controls. Staining for MMP-1/-13 and, TIMP-1/-2 in KBD patients was prominent in the superficial zone and the middle zone of articular cartilage. Staining for ITEGE and DIPEN neoepitopes in KBD samples was prominent in the superficial zone and the middle zone of articular cartilage. The strongest staining for the MMP and aggrecanase-generated neoepitopes was adjacent to areas of chondronecrosis. These results indicated that KBD cartilage destruction depends on collagen- and aggrecan-degrading proteases such as collagenases (MMP-1/-13), as well as aggrecanases. Increased TIMP-2 level adjacent to necrotic areas suggest that attempted repair mechanism are also activated.

Recent advances in the research of an endemic osteochondropathy in China: Kashin-Beck disease

Kashin-Beck disease (KBD) is an endemic chronic osteochondral disease, which has a high prevalence and morbidity in the Eastern Siberia of Russia, and in the broad diagonal, northern-east to southern-west belt in China and North Korea. In 1990's, it was estimated that in China 1-3 million people had some degree of symptoms of the disease, although even higher estimates have been presented. In China, the extensive prevalence peaked in the late 1950's, but since then, in contrast to the global trend of the osteoarthritis (OA), the number of cases has been dramatically falling. Up to 2013, there are 0.64 millions patients with the KBD and 1.16 millions at risk in 377 counties of 13 provinces or autonomous regions. This is obviously thanks to the preventive efforts carried out, which include providing millions of people with dietary supplements and clean water, as well as relocation of whole villages in China. However, relatively little is known about the molecular mechanisms behind the cartilage damage, the genetic and the environmental risk factors, and the rationale of the preventive effects. During the last decade, new data on a cellular and molecular level has begun to accumulate, which hopefully will uncover the grounds of the disease.

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.

Serum levels of M-CSF, RANKL and OPG in rats fed with Kashin-Beck disease-affected diet

Objective

There were no studies on the macrophage colony-stimulating factor (M-CSF), receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG) in the pathogenesis of Kashin-Beck disease (KBD). The objective of the present study was to investigate the serum M-CSF, RANKL and OPG in rats fed with KBD-affected diet.

Methods

Ninety Wistar rats were divided into five groups. The rats received standard commercial feed with or without T-2 toxin additive, low protein feed with or without or T-2 toxin additive and the KBD-affected feed. The serum bioactivity of M-CSF, RANKL and OPG was tested by enzyme-linked immunosorbent assay.

Results

The serum levels of M-CSF in E group rats were higher than those in the other groups in the five groups (P < 0.01). The serum levels of RANKL and OPG in E group rats were highest in the five groups and have significant difference compared to the other groups (P < 0.05).

Conclusions

The molecule of M-CSF, RANKL and OPG may be involved in the regulation of epiphyseal plate injury and repair in KBD, and its participation in the pathogenesis of KBD should be studied in the future.

Gene expression analysis suggests bone development-related genes GDF5 and DIO2 are involved in the development of Kashin-Beck disease in children rather than adults

OBJECTIVE

To investigate the differences in gene expression between children and adults with Kashin-Beck disease (KBD).

METHODS

12 children with KBD and 12 healthy children were selected and divided into 4 KBD vs. control pairs matched according to age and gender, with each pair having 3 KBD children and 3 healthy children. Additionally, 15 adults with KBD and 15 healthy adults were selected and divided into 5 KBD vs. control pairs matched according to age and gender, with each pair having 3 KBD adults and 3 healthy adults. Total RNA was isolated from peripheral blood mononuclear cells (PBMCs) respectively. A total of 367 target genes were selected based on previous genome-wide gene expression profile analysis. Expression levels of the 367 genes were evaluated by customized oligonucleotide microarray and the differentially expressed genes were identified. Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) was conducted to validate the microarray data.

RESULTS

A total of 95 (25.9%) genes in KBD children and 158 (43.1%) genes in KBD adults were found to exhibit more than two-fold change in gene expression level relative to healthy controls. By comparing differentially expressed genes identified in KBD children to those of KBD adults, 42 genes were found to be differentially expressed only in KBD children. And 105 genes were found to be differentially expressed only in KBD adults. Further, 16 differentially expressed genes common to both KBD children and adults were found to be asynchronously expressed in KBD children compared to KBD adults.

CONCLUSION

Significant differences in gene expression pattern were identified between KBD children and KBD adults, indicating different molecular mechanisms underlying cartilage lesions of KBD children and KBD adults. In addition, bone development-related genes GDF5 (expression ratio = 2.14±0.02) and DIO2 (expression ratio = 0.11±0.05) may contribute to the development of KBD in children rather than in adults.

Magnetic resonance imaging in the tibial epiphyseal growth plate development of Wistar rat

OBJECTIVE

This research aims to investigate magnetic resonance imaging (MRI) in the tibial epiphyseal growth plate development of Wistar rat.

METHODS

Fifty weanling Wistar rats were divided by a computerized blocking procedure into five groups. The rats received standard commercial feed with or without T-2 toxin additive, low-protein feed with or without T-2 toxin additive, and Kashin-Beck disease (KBD)-affected feed.

RESULTS

Compared with the control group rat, MRI showed localized epiphyseal plate swelling, rough appearance, and uneven signal on the tibia of rats fed with KBD-affected feed. Histology confirmed the epiphyseal plate degeneration seen by MRI, and the degenerative changes were characterized by abnormal distribution of chondrocytes with loss and clustering, cartilage fragmentation, and erosion in group E.

CONCLUSIONS

The MR image of the rat epiphyseal plate is altered in the KBD model rats, and epiphyseal plate MRI appearance has been reproduced by using T-2 toxin and KBD-affected feed of epidemic district.

Mesenchymal stem cells in joint disease and repair

Osteoarthritis (OA), a prevalent chronic condition with a striking impact on quality of life, represents an enormous societal burden that increases greatly as populations age. Yet no approved pharmacological intervention, biologic therapy or procedure prevents the progressive destruction of the OA joint. Mesenchymal stem cells (MSCs)-multipotent precursors of connective tissue cells that can be isolated from many adult tissues, including those of the diarthrodial joint-have emerged as a potential therapy. Endogenous MSCs contribute to maintenance of healthy tissues by acting as reservoirs of repair cells or as immunomodulatory sentinels to reduce inflammation. The onset of degenerative changes in the joint is associated with aberrant activity or depletion of these cell reservoirs, leading to loss of chondrogenic potential and preponderance of a fibrogenic phenotype. Local delivery of ex vivo cultures of MSCs has produced promising outcomes in preclinical models of joint disease. Mechanistically, paracrine signalling by MSCs might be more important than differentiation in stimulating repair responses; thus, paracrine factors must be assessed as measures of MSC therapeutic potency, to replace traditional assays based on cell-surface markers and differentiation. Several early-stage clinical trials, initiated or underway in 2013, are testing the delivery of MSCs as an intra-articular injection into the knee, but optimal dose and vehicle are yet to be established.

The expression of p-ATF2 involved in the chondeocytes apoptosis of an endemic osteoarthritis, Kashin-Beck disease

Background

The purpose of the study was to understand the function and expression of ATF2 by JNK and p38 signal pathways in the chondrocytes apoptosis of articular cartilage of the Kashin-Beck disease (KBD).

Methods

The changes of ATF2, JNK and p38 mRNAs and proteins were investigated between cartilage and chondrocyte as well as KBD and normal. JNK and p38 inhibitors were used as treatments to prevent apoptosis in chondrocytes from KBD patients.

Results

It was found that the protein levels of p-p38, p-JNK, ATF2 and p-ATF2 increased in KBD human cartilage which is in line with the higher mRNA levels of p38, JNK and ATF2 as compared both with normal cartilage and KBD chondrocytes. In addition, p-ATF2 was only detected in KBD cartilage. Furthermore, JNK inhibitor was more effective than p38 inhibitor in preventing chondrocyte apoptosis at equal concentrations of 10 μM.

Conclusion

These findings indicated the expression of p-ATF2 by JNK and p38 signal pathways involved in the chondrocyte apoptosis in cartilage with KBD.

Abnormal expression of chondroitin sulphate N-acetylgalactosaminyltransferase 1 and Hapln-1 in cartilage with Kashin-Beck disease and primary osteoarthritis

Purpose

Kashin-Beck disease (KBD) is an endemic degenerative osteoarthritis associated with extracellular matrix degradation. The aim of this investigation was to evaluate the role of targeting genes in the pathogenesis of KBD and primary osteoarthritis (OA) involved in extracellular matrix degradation.

Methods

Agilent 44 K human whole-genome oligonucleotide microarrays were used to detect the gene expression in KBD and OA cartilage. The mRNA and protein expressions of CSGalNAcT-1 and Hapln-1 in chondrocytes were verified by reverse transcription polymerase chain reaction (RT-PCR) and western blot, and their expression in cartilage were verified with immunocytochemical analysis. Meanwhile, CSGalNAcT-1 and Hapln-1 protein levels in the selenium intervention group of KBD with different concentrations (0.25, 0.1and 0.05 μg/ml) were detected by western blot.

Results

CSGalNAcT-1 and Hapln-1 were down-regulated in KBD and OA at both mRNA and protein levels, and were increased in Se(Selenium) groups compared to KBD free-Se group. However, Wnt 3a, β-catenin and Runx-2 were up-regulated in OA and KBD at protein levels. Additionally, immunohistochemical staining showed that CSGalNAcT-1 and Hapln-1 were reduced in all zones of KBD and OA articular cartilage, but not significantly reduced in the up zone of OA articular cartilage.

Conclusions

The CSGalNAcT-1 and Hapln-1 were down-regulated in both KBD and OA cartilage. CSGalNAcT-1 may be involved in the damage of articular cartilage of KBD and OA by regulating Hapln-1 in the Wnt/β-catenin signalling pathway. It was indicated that CSGalNAcT-1 and Hapln-1 may play important roles in the pathogenesis of KBD and OA.

Genetic variants in the HLA-DRB1 gene are associated with Kashin-Beck disease in the Tibetan population

OBJECTIVE

To investigate the association between variants in the HLA-DRB1 gene and Kashin-Beck disease (KBD), as well as associations of selenium and iodine deficiencies with KBD in a Tibetan population.

METHODS

Fourteen single-nucleotide polymorphisms (SNPs) were genotyped around the HLA-DRB1 gene, and HLA-DRB1 allele genotyping was performed in a discovery cohort, composed of 605 patients with KBD and 393 control subjects, and/or a replication cohort, composed of 290 patients with KBD and 295 controls. Plasma concentrations of selenium and iodine were measured and compared by t-test in 299 patients with KBD and 280 controls from the same villages.

RESULTS

Four SNPs (rs6457617, rs6457620, rs9275295, and rs7745040) in the HLA-DRB1 gene locus were significantly associated with KBD in both the discovery cohort and replication cohort (combined cohort odds ratios [ORs] 1.307-1.402, P = 0.0039-0.0006). The protective haplotype GTCC and the risk haplotype ACGT, each generated by the 4 SNPs, showed a significant association with KBD (for GTCC, OR 0.77, P = 0.0031; for ACGT, OR 1.40, P = 0.0014). HLA-DRB1 allele genotyping revealed that the frequencies of HLA-DRB1*08 and *11 were significantly different between patients with KBD and controls (for HLA-DRB1*08, OR 0.731, P = 0.00564; for HLA-DRB1*11, OR 0.489, P = 0.000395). Moreover, plasma concentrations of selenium and iodine were significantly different between patients with KBD and controls from the same villages (P = 0.0013 and P = 1.84 × 10(-12) , respectively).

CONCLUSION

These findings, obtained in plasma samples from Tibetan patients with KBD and healthy control subjects from the same regions, confirm the role of selenium and iodine deficiencies in the development of KBD. Moreover, genetic variants in the HLA-DRB1 gene significantly increase the susceptibility to KBD in this population.

Pathways related to mitochondrial dysfunction in cartilage of endemic osteoarthritis patients in China

In this paper, we present the first evidence of differences in the mitochondria-related gene expression profiles of adult articular cartilage derived from patients with Kashin-Beck disease and normal controls. The expression of 705 mitochondria-related genes was analyzed by mitochondria-related gene expression analysis and ingenuity pathways analysis. Mitochondria-related gene expression analysis identified 9 up-regulated genes in Kashin-Beck disease based on their average expression ratio. Three canonical pathways involved in oxidative phosphorylation, apoptosis signaling and pyruvate metabolism were identified, which indicate the involvement of mitochondrial dysfunction in the pathogenesis of Kashin-Beck disease.

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.

Altered Aggrecan Synthesis and Collagen Expression Profiles in Chondrocytes from Patients with Kashin—Beck Disease and Osteoarthritis

OBJECTIVES: To investigate cell morphology, aggrecan expression, and type I, II, III and X collagen expression in chondrocytes from adults with Kashin—Beck disease or osteoarthritis (OA). METHODS: Samples of knee articular cartilage were taken during surgery; cartilage samples obtained from fresh cadavers without arthritic disease were used as controls. Samples were digested with collagenase; isolated chondrocytes were cultured in monolayers. Aggrecan was detected by toluidine blue staining; collagen and aggrecan protein levels were evaluated by immuno cytochemistry and immunofluorescence staining. RESULTS: Samples were obtained from six participants per group. Aggrecan and type II collagen levels in chondrocytes from patients were significantly lower than those from controls, but levels of type I, III and X collagen were enhanced in patients compared with controls. Production of type III and X collagen was higher in chondrocytes from patients with Kashin—Beck disease than in those from OA patients. CONCLUSIONS: Biochemical and morphological mechanisms underlying Kashin—Beck disease and OA include enhanced dedifferentiation and hypertrophy of chondrocytes, increased type I, III and X collagen levels, and suppressed type II collagen and aggrecan production compared with control samples.

Expression profile analysis of mycotoxin-related genes in cartilage with endemic osteochondropathy Kashin-Beck Disease

BACKGROUND

Kashin-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.

METHODS

Total 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.

RESULTS

We 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.

CONCLUSIONS

Based 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.

Genome-wide study identifies the regulatory gene networks and signaling pathways from chondrocyte and peripheral blood monocyte of Kashin-Beck disease

This investigation was designed to unravel gene networks in Kashin-Beck disease (KBD) and better identify target genes of KBD for gene therapy development. RNA was isolated separately from cartilage and peripheral blood samples of patients with KBD and healthy controls. Agilent 44K human whole-genome oligonucleotide microarrays were used to detect differentially expressed genes. Three significant canonical pathways and nine chondrocyte networks from chondrocytic gene expression profiles were screened using ingenuity pathway analysis (IPA), but only one network and no canonical pathways from peripheral blood monocytic gene profile were identified. Bak1, APAF-1, CASP6, IGFBP2, Col5a2 and TGFBI extracted from significant genes that involved in chondrocytic canonical pathways and networks may have closer relationship with the etiopathogenesis of KBD. Those genes may be potential targets for gene diagnosis and treatment. Six physiological functions were predominant and unique to the chondrocytic genes, whereas two were unique to peripheral blood monocytic genes. The identified genes may represent a source of potentially novel molecular targets, which may provide a better understanding of the molecular details in KBD pathogenesis and also provide useful pathways and network maps for the future research in osteochondrosis.

Genome-wide gene expression analysis suggests an important role of suppressed immunity in pathogenesis of Kashin-Beck disease

Objective

To investigate the differences between the gene expression profiles in peripheral blood mononuclear cells (PBMC) from normal controls and patients with Kashin-Beck disease (KBD).

Methods

Twenty KBD patients and 12 normal subjects were selected from a KBD-endemic area and divided into four pairs of KBD vs. control (KBD, n = 5 per pair; control, n = 3 per pair). RNAs were respectively isolated from KBD PBMCs and normal PBMCs. Gene expression profiles were analyzed by oligonucleotide microarray. The gene expression profiles in PBMCs from KBD patients and normal controls were compared and the differentially expressed genes were identified. The obtained microarray data was further confirmed by using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR).

Results

Approximately 501 genes, corresponding to 2.4% of the total probe transcripts, showed a 2-fold change in differential expression. 19.4% (97 out of 501)of the differentially expressed genes were commonly detected in all the four pairs. Among the 97 differentially expressed genes, 83 genes were up-regulated and 14 genes were down-regulated, compared with those in the normal controls. Some differentially expressed genes were found to be related to functions such as immunity, metabolism, apoptosis, cystoskeleton and cell movement, and extracellular matrix. The validity of our microarray data were supported by the results of qRT-PCR assay.

Conclusion

Differences in the PBMC gene expression profile between the KBD patients and the normal controls exhibited a similar pattern among all the four pairs of microarrays examined, indicating that the suppressed immunity may play an important role in the pathogenesis of KBD.

Genome-wide gene expression analysis suggests an important role of hypoxia in the pathogenesis of endemic osteochondropathy Kashin-Beck disease

Kashin-Beck Disease (KBD) is an endemic osteochondropathy, the pathogenesis of which remains unclear now. In this study, we compared gene expression profiles of articular cartilage derived respectively from KBD patients and normal controls. Total RNA were isolated, amplified, labeled and hybridized to Agilent human 1A 22 k whole genome microarray chip. qRT-PCR was conducted to validate our microarray data. We detected 57 up-regulated genes (ratios ≥2.0) and 24 down-regulated genes (ratios ≤0.5) in KBD cartilage. To further identify the key genes involved in the pathogenesis of KBD, Bayesian analysis of variance for microarrays (BAM) software was applied and identified 12 potential key genes with an average ratio 6.64, involved in apoptosis, metabolism, cytokine & growth factor and cytoskeleton & cell movement. Gene Set Enrichment Analysis (GSEA) software was used to identify differently expressed gene ontology categories and pathways. GSEA found that a set of apoptosis, hypoxia and mitochondrial function related gene ontology categories and pathways were significantly up-regulated in KBD compared to normal controls. Based on the results of this study, we suggest that chronic hypoxia-induced mitochondrial damage and apoptosis might play an important role in the pathogenesis of KBD. Our efforts may help to understand the pathogenesis of KBD as well as other osteoarthrosis with similar articular cartilage lesions.

Proteomic changes in articular cartilage of human endemic osteoarthritis in China

Kashin-Beck disease (KBD) is a chronic endemic osteochondropathy with unclear pathogenesis. It is a degenerative disease similar to osteoarthritis, but with different manifestations of cartilage damage. The aim of this investigation was to show the protein changes in KBD cartilage and to identify the candidate proteins in order to understand the pathogenesis of the disease. Proteins were extracted from the media of primary cell cultures of KBD and normal chondrocytes, and separated by two-dimensional fluorescence difference gel electrophoresis (2-D DIGE). MALDI-TOF/TOF analysis revealed statistically significant differences in 27 proteins from KBD chondrocyte cultures, which consisted of 17 up-regulated and ten down-regulated proteins. The results were further validated by Western blot analysis. The proteins identified are mainly involved in cellular redox homeostasis and stress response (MnSOD, Hsp27, Peroxiredoxin-1, and Cofilin-1), glycolysis (PGK-1, PGM-1, α-enolase), and cell motility and cytoskeletal organization (Actin, Calponin-2, and Keratin). These KBD-associated proteins indicate that cytoskeletal remodeling, glycometabolism, and oxidative stress are abnormal in KBD articular cartilage.

Mitochondrial function is altered in articular chondrocytes of an endemic osteoarthritis, Kashin-Beck disease

OBJECTIVE

Kashin-Beck disease (KBD) is an endemic degenerative osteoarthritis (OA) associated with extracellular matrix degradation and chondrocyte necrosis in the articular and growth plate cartilage. The role of mitochondria in degenerative diseases is widely recognized but its function in KBD is unknown. The aim of this investigation was to evaluate mitochondrial function to understand the mitochondria-mediated caspase activation and apoptosis in adult KBD chondrocytes.

METHODS

Mitochondrial function was evaluated by analyzing the activities of respiratory chain enzyme complexes and citrate synthase (CS), intracellular adenosine triphosphate (ATP) contents, as well as changes in mitochondrial membrane potential (DeltaPsim). Apoptotic cell death was evaluated by analyzing the cytochrome c release from mitochondria to the cytosol, caspase-9 and 3 activities, and the apoptosis rate of KBD articular chondrocytes.

RESULTS

Activities of complexes II, III, IV and V were reduced in KBD articular chondrocytes compared with cells from normal controls. However, the mitochondrial mass was increased in KBD samples. Cultured KBD chondrocytes had a reduction of cellular ATP levels and contained a higher proportion of cells with de-energized mitochondria. Mitochondrial cytochrome c release and activation of caspase-9 and 3 were also observed. The percentages of positive apoptotic chondrocytes from the KBD patient group stained by Hoechst nuclear stain and Annexin V/PI for flow cytometry exhibited higher levels than that of the healthy controls.

CONCLUSION

These findings suggest the involvement of mitochondrial function and apoptotic cell death in the pathophysiology of KBD. The dysfunction of the mitochondria may play an important role in KBD articular chondrocytes apoptosis.