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

Activation of Notch Signaling Pathway is involved in Extracellular Matrix Degradation in human induced pluripotent stem cells chondrocytes induced by HT-2 toxin

Notch signaling regulates cartilage formation and homeostasis. Kashin-Beck Disease (KBD), an endemic osteochondropathy, is characterized by severe cartilage degradation. The etiology of KBD is related to the exposure of HT-2 toxin, a mycotoxin and primary metabolite of T-2 toxin. This study aims to explore the role of HT-2 toxin in the Notch signaling regulation and extracellular matrix (ECM) metabolism of hiPSCs-Chondrocytes. Immunohistochemistry and qRT-PCR were employed to investigate the expression of Notch pathway molecules in KBD articular cartilage and primary chondrocytes. hiPSCs-Chondrocytes, derived from hiPSCs, were treated with 100 ng/mL HT-2 toxin and the γ-secretase inhibitor (DAPT) for 48h, respectively. The markers related to the Notch signaling pathway and ECM were assessed using qRT-PCR and Western blot. Notch pathway dysregulation was prominent in KBD cartilage. HT-2 toxin exposure caused cytotoxicity in hiPSCs-Chondrocytes, and activated Notch signaling by increasing the mRNA and protein levels of NOTCH1 and HES1. HT-2 toxin also upregulated ECM catabolic enzymes and downregulated ECM components (COL2A1 and ACAN), indicating ECM degradation. DAPT-mediated Notch signaling inhibition suppressed the mRNA and protein level of ADAMTS5 expression while enhancing ECM component expression in hiPSCs-Chondrocytes. This study suggests that HT-2 toxin may induce ECM degradation in hiPSCs-Chondrocytes through activating Notch signaling.

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.

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.

Upregulated expression of transforming growth factor-β receptor I/II in an endemic Osteoarthropathy in China

Background

Kashin–Beck disease (KBD) is a chronic, deforming, endemic osteochondropathy that begins in patients as young as 2–3 years of age. The pathogenesis of KBD remains unclear, although selenium (Se) deficiency and T-2 toxin food contamination are both linked to the disease. In the present study, we evaluated transforming growth factor-β receptor (TGF-βR I and II) levels in clinical samples of KBD and in pre-clinical disease models.

Methods

Human specimens were obtained from the hand phalanges of eight donors with KBD and eight control donors. Animal models of the disease were established using Sprague–Dawley rats, which were fed an Se-deficient diet for 4 weeks and later administered the T-2 toxin. Cartilage cellularity and morphology were examined by hematoxylin and eosin staining. Expression and localization of TGF-βRI and II were evaluated using immunohistochemical staining and western blotting.

Results

In the KBD samples, chondral necrosis was detected based on cartilage cell disappearance and alkalinity loss in the matrix ground substance. In the necrotic areas, TGF-βRI and II staining were strong. Positive percentages of TGF-βRI and II staining were higher in the cartilage samples of KBD donors than in those of control donors. TGF-βRI and II staining was also increased in cartilage samples from rats administered T-2 toxin or fed on Se-deficient plus T-2 toxin diets.

Conclusion

TGF-βRI and II may be involved in the pathophysiology of KBD. This study provides new insights into the pathways that contribute to KBD development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04939-6.

Downregulation of Insulin-Like Growth Factor-1 Receptor Mediates Chondrocyte Death and Matrix Degradation in Kashin-Beck Disease

PURPOSE

To explore the relationship between insulin-like growth factor (IGF)-1R expression and the pathological progression of Kashin-Beck disease (KBD).

DESIGN

KBD cartilage samples were collected from 5 patients. Additionally, T-2 toxin was administered to rats fed a selenium (Se)-deficient diet, and their knee joints were collected. Human C28/I2 chondrocytes and mouse hypertrophic ATDC5 chondrocytes were cultured in vitro and treated with T-2 toxin and Se supplementation. Subsequently, the cultured human and mouse chondrocytes were treated with the IGF-1R inhibitor, picropodophyllin. Chondrocyte death and caspase-3 activity were analyzed using flow cytometry and a specific kit, respectively. Protein and mRNA expression levels of IGF-1R and matrix molecules were measured using immunohistochemistry, western blotting, and quantitative real-time reverse transcription-polymerase chain reaction analyses.

RESULTS

The cartilages from patients with KBD and T-2 toxin-treated rats on a Se-deficient diet showed significantly decreased expression of IGF-1R compared to cartilages from controls. T-2 toxin decreased IGF-1R mRNA and protein levels in both C28/I2 and hypertrophic ATDC5 chondrocytes in a dose-dependent manner; however, Se supplementation reduced the decrease of IGF-1R induced by T-2 toxin. Furthermore, inhibition of IGF-1R resulted in chondrocyte death of C28/I2 and hypertrophic ATDC5 chondrocytes, as well as decreased type II collagen expression and increased MMP-13 expression at the mRNA and protein levels.

CONCLUSION

Downregulation of IGF-1R was associated with KBD cartilage destruction. Therefore, inhibition of IGF-1R may mediate chondrocyte death and extracellular matrix degeneration related to the pathological progression of KBD.

The decreased expression of integrin αv is involved in T-2 toxin-induced extracellular matrix degradation in chondrocytes

T-2 toxin is one of the most toxic and common mycotoxins in grains and related products. It is considered a risk factor for Kashin-Beck disease (KBD), an endemic osteoarthritis. Both in vitro and in vivo studies have shown that T-2 toxin can cause extracellular matrix degradation; however, the underlying mechanism is unclear. Integrins have been found to regulate the expression of matrix metalloproteinases (MMPs), the 'scissors' of matrix proteins. In this study, we investigated whether integrin αv played a role in T-2 toxin-induced matrix degradation. Results from our study showed that the expression of integrin αv in the cartilage of rats fed T-2 toxin was reduced compared to that in rats fed a normal diet. Integrin αv was downregulated in T-2 toxin-treated C28/I2 chondrocytes, and selenium was found to have a protective effect. The expression of MMP-1, -3, -10, and -13 increased whereas that of type II collagen (Col II) protein decreased in C28/I2 cells treated with an integrin αv inhibitor. In conclusion, T-2 toxin can downregulate integrin αv expression in chondrocytes. Reduced integrin αv signalling could induce the release of MMPs, leading to matrix degradation.

Feprazone Ameliorates TNF-α-Induced Loss of Aggrecan via Inhibition of the SOX-4/ADAMTS-5 Signaling Pathway

Background: Arthritis is a cartilage degenerative disease that is mainly induced by the degradation of the cartilage extracellular matrix (ECM), which is found to be regulated by the expression level of a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMT-5), an enzyme degrading Aggrecans in the ECM. Feprazone is a classic nonsteroidal anti-inflammatory drug with promising efficacy in arthritis. The present study aims to investigate the protective effect of Feprazone on the degraded Aggrecan in the human chondrocytes induced with tumor necrosis factor-α (TNF-α) and to clarify the underlying mechanism. Methods: To investigate the effect of Feprazone, the CHON-001 chondrocytes were stimulated with TNF-α (10 ng/mL) in the presence or absence of Feprazone (3, 6 μM) for 24 h. Mitochondrial membrane potential was evaluated using the Rhodamine 123 assay. The gene expressions of interleukin-1β (IL-1β), interleukin-8 (IL-8), monocyte chemotactic protein 1 (MCP-1), and ADAMTS-5 in the treated chondrocytes were detected using real-time quantitative polymerase chain reaction (qRT-PCR), and the protein levels of these targets were determined using enzyme-linked immunosorbent assay (ELISA). SOX-4 was knocked down by transfecting the siRNA into the chondrocytes. Western blot analysis was utilized to evaluate the expression levels of SOX-4, Aggrecan, and protein kinase C (PKCα). Results: First, the reduced mitochondrial membrane potential (ΔΨ_m) and secretion of proinflammatory factors (IL-1β, IL-8, and MCP-1) induced by TNF-α were significantly reversed by treatment with Feprazone. Second, the expression of Aggrecan was significantly decreased by stimulation with TNF-α via upregulation of ADAMTS-5 but was dramatically reversed by the introduction of Feprazone. Third, we found that TNF-α elevated the expression of ADAMTS-5 by upregulating SOX-4, which was observed to be related to the activation of PKCα. Lastly, the elevated expression of SOX-4 induced by TNF-α was significantly reversed by Feprazone. Conclusions: Feprazone might ameliorate TNF-α-induced loss of Aggrecan via the inhibition of the SOX-4/ADAMTS-5 signaling pathway.

Decreased Expression of Heat Shock Protein 47 Is Associated with T-2 Toxin and Low Selenium-Induced Matrix Degradation in Cartilages of Kashin-Beck Disease

Recent evidence suggests a role of type II collagen in Kashin-Beck disease (KBD) degeneration. We aimed to assess the abnormal expression of heat shock protein 47 (HSP47) which is associated with a decrease in type II collagen and an increase in cartilage degradation in KBD. Hand phalange cartilages were collected from KBD and healthy children. Rats were administered with T-2 toxin under the selenium (Se)-deficient diet. ATDC5 cells were seeded on bone matrix gelatin to construct engineered cartilaginous tissue. C28/I2 and ATDC5 cells and engineered tissue were exposed to different concentrations of T-2 toxin with or without Se. Cartilage degeneration was determined through histological evaluation. The distribution and expression of type II collagen and HSP47 were investigated through immunohistochemistry, western blotting, and real-time PCR. KBD cartilages showed increased chondronecrosis and extracellular matrix degradation in deep zone with decreased type II collagen and HSP47 expression. The low-Se + T-2 toxin animal group showed a significantly lower type II collagen expression along with decreased HSP47 expression. Decreased type II collagen and HSP47 in C28/I2 and ATDC5 cells induced by T-2 toxin showed a dose-dependent manner. Hyaline-like cartilage with zonal layers was developed in engineered cartilaginous tissues, with decreased type II collagen and HSP47 expression found in T-2 toxin-treated group. Se-supplementation partially antagonized the inhibitory effects of T-2 toxin in chondrocytes and cartilages. HSP47 plays a role in the degenerative changes of KBD and associated with T-2 toxin-induced decreased type II collagen expression, further promoting matrix degradation.

Inhibiting the aberrant activation of Wnt/β-catenin signaling by selenium supplementation ameliorates deoxynivalenol-induced toxicity and catabolism in chondrocytes

Kashin-Beck disease (KBD) is an endemic degenerative osteoarticular disorder associated with physical disability and a heavy economic burden. Contamination by mycotoxin deoxynivalenol (DON) and selenium deficiency have been proposed to be key etiological factors for KBD, and can work together to aggravate the progression of KBD. Nevertheless, the mechanism of DON in KBD remains elusive. In the present study, exposure to DON dose-dependently suppressed cell viability and expression of pro-proliferation marker PCNA in human chondrocytes, whereas it enhanced lactate dehydrogenase release, cell apoptosis, and caspase-3/9 activity. In addition, DON incubation shifted metabolism homeostasis towards catabolism by suppressing the transcription of collagen II and aggrecan, and the production of sulphated glycosaminoglycans and TIMP-1, while increasing matrix metalloproteinase levels (MMP-1 and MMP-13). Mechanistically, DON exposure induced the activation of Wnt/β-catenin signaling. Intriguingly, blocking this pathway reversed the adverse effects of DON on cytotoxic damage and metabolism disruption to catabolism. Notably, supplementation with selenium reduced DON-induced activation of the Wnt/β-catenin pathway. Moreover, selenium addition abrogated cytotoxic injury and excessive pro-catabolic gene expression in chondrocytes upon DON conditions. These findings confirm that DON may facilitate the development of KBD by inducing cell injury, inhibiting matrix synthesis, and increasing cellular catabolism by activating the Wnt/β-catenin signaling, which were partially reversed by selenium supplementation. Thus, the current study may presents a new viewpoint for how selenium supplementation ameliorates the development of KBD by inhibiting DON-induced cytotoxic injury and metabolism imbalance in chondrocytes.

ADAMTS4 and ADAMTS5 may be considered as new molecular therapeutic targets for cartilage damages with Kashin-Beck Disease

There are a pretty number of research demonstrating that ADAMTS4 and ADAMTS5 playing primary roles in the degradation of cartilage during inflammatory joint diseases like osteoarthritis (OA). Because Kashin-Beck Disease (KBD) has been found to own the common pathological changes and symptoms with OA, and is regarded as the specific type of osteoarthritis, it's reasonable to believe that ADAMTS4 and ADAMTS5 may exert an enormous functions on the injury of cartilage of the KBD and may be potential molecular therapeutic targets for 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.

Pathway-based network analyses and candidate genes associated with Kashin-Beck disease

To perform a comprehensive analysis focusing on the biological functions and interactions of Kashin-Beck disease (KBD)-related genes to provide information towards understanding the pathogenesis of KBD.A retrospective, integrated bioinformatics analysis was designed and conducted. First, by reviewing the literature deposited in PubMed, we identified 922 genes genetically associated with KBD. Then, biological function and network analyses were conducted with Cytoscape software. Moreover, KBD specific molecular network analysis was conducted by Cytocluster using the Molecular Complex Detection Algorithm (MCODE).The biological function enrichment analysis suggested that collagen catabolic process, protein activation cascade, cellular response to growth factor stimulus, skeletal system development, and extrinsic apoptosis played important roles in KBD development. The apoptosis pathway, NF-kappa B signaling pathway, and the glutathione metabolism pathway were significantly enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway network, suggesting that these pathways may play key roles in KBD occurrence and development. MCODE clusters showed that in top 3 clusters, 54 of KBD-related genes were included in the network and 110 candidate genes were discovered might be potentially related to KBD.The 110 candidate genes discovered in the current study may be related to the development of KBD. The expression changes of apoptosis and oxidative stress-related genes might serve as biomarkers for early diagnosis and treatment of KBD.

Matrix metalloproteinase-9 and p53 involved in chronic fluorosis induced blood-brain barrier damage and neurocyte changes

INTRODUCTION

A large number of basic and clinical studies have confirmed that fluoride produces toxic effects on multiple organ systems in the body including the nervous system.

MATERIAL AND METHODS

One hundred twenty Wistar rats were randomly divided into 4 groups with 30 in each group: a high fluoride group (drinking 200 mg/l fluoridated water, 24 weeks); a high fluoride control group (drinking distilled water, 24 weeks); a fluoride removal group (drinking fluoridated water, 12 W; then distilled water, 12 W) and a defluorination control group (drinking distilled water, 24 weeks).

RESULTS

The high fluoride and fluoride removal groups had spinal cord astrocyte edema. The apoptosis rate of spinal nerve cells in the high fluoride group and fluoride removal group were significantly higher (p < 0.01) than in the fluoride control and defluorination control group. The Evans blue (EB) content, matrix metalloproteinase-9 (MMP-9) and p53 expression in the high fluoride group and fluoride removal group were higher (p < 0.01) than in the fluoride control and defluorination control group.

CONCLUSIONS

The apoptosis of spinal cord nerve cells is obviously higher in rats with chronic fluoride exposure. Chronic fluoride exposure leads to high expression of MMP-9, and results in increased damage of the blood-spinal cord barrier. Increased p53 may be one of the factors causing damage. Short-term removal of fluoride has no obvious recovery in apoptosis of spinal cord nerve cells; highly expressed MMP-9 and p53 may be one of the reasons for unrecovered function.

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.

Dietary exosome-miR-23b may be a novel therapeutic measure for preventing Kashin-Beck disease

Previous studies have identified a close association between diet and the prevalence of Kashin-Beck disease (KBD); however, the mechanisms via which the diet protects against KBD-associated cartilage injury has remained elusive. Recent international research studies have revealed a therapeutic role of dietary exosome micro (mi)RNAs in repairing chondrocyte lesions by regulating genes and proteins associated with cellular apoptosis and extracellular matrix. Vital molecules affecting bio-functions of chondrocytes, including miR-23b and protein kinase cyclic AMP-activated catalytic subunit β, were preliminarily identified to be dysregulated in cells and cartilage tissue of KBD patients. The function of dietary exosome in the repair of chondrocyte lesions in KBD is a novel topic in this field. It is worth exploring the protective role of dietary exosome-miR-23b against chondrocyte damage through the regulation of the protein kinase A (PKA) signaling pathway. The following aims are significant in future studies: i) To verify the association between exosome and cartilage damage in KBD patients; ii) to identify whether the protective mechanism of miR-23b in cartilage damage proceeds through regulating the PKA pathway; and iii) to explore the therapeutic role of dietary exosome-miR-23b in repairing chondrocyte lesions induced by environmental risk factors. These ideas may help establish the therapeutic role and mechanisms of dietary exosome-miR-23b in repairing chondrocyte lesions at the molecular, cellular and organismal level. These studies may simultaneously elucidate the disease pathogenesis and provide evidence for novel biomarkers and therapeutic methods for KBD.

Serum and Hair Zinc Levels in Patients with Endemic Osteochondropathy in China: A Meta-analysis

A large number of studies have shown growing interest in the zinc (Zn) levels of serum and hair samples collected from patients with Kashin-Beck disease (KBD), an endemic chronic osteochondral disease. However, inconsistent conclusions regarding the serum and hair Zn levels have been made. The aim of this study is to assess and to explore the change in serum and hair Zn levels among KBD patients. Multiple databases, including PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI), Wanfang database and Technology of Chongqing (VIP), were carefully searched for available studies up to January 13, 2017 in this integrated analysis. Standard mean difference (SMD) with a 95% confidence interval (95% CI) was calculated using STATA 11.0. A total of 18 studies, involving 978 KBD cases and 1116 healthy controls, were collected in this analysis. Pooled analysis found the KBD patients had a higher hair Zn level and a lower serum Zn level than the healthy controls (hair Zn (μg/g), SMD = 0.030, 95% CI = -0.315, 0.376; serum Zn (mg/L), SMD = -0.069, 95%CI = -0.924, 0.785). Meta-regression method and sensitivity analysis were utilized to analyze the heterogeneity of data. Positive correlations were separately identified between hair Zn level in KBD patients (r = 0.4639, P = 0.032) and controls (r = 0.4743, P = 0.012) and the survey year. No evidence of publication bias was observed. The available results suggest that increased hair Zn level and decreased serum Zn level are commonly found in KBD patients; however, the role of Zn in the etiology and pathogenesis of KBD could not yet be confirmed.

Comparative Analysis of Gene Expression Profiles of Human Dental Fluorosis and Kashin-Beck Disease

To explore the pathologies of Kashin-Beck disease (KBD) and KBD accompanied with dental fluorosis (DF), we conducted a comparative analysis of gene expression profiles. 12 subjects were recruited, including 4 KBD patients, 4 patients with KBD and DF and 4 healthy subjects. Genome-wide expression profiles from their peripheral blood mononuclear cells were evaluated by customized oligonucleotide microarray. R programming software was used for the microarray data analysis followed by functional enrichment analysis through KOBAS. Several potential biomarkers were identified, and quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) was used for their validation. In this study, 28 genes and 8 genes were found to be up- and down-regulated respectively in KBD patients compared with health subjects. In patients with KBD and DF, we obtained 10 up-regulated and 3 down-regulated genes compared with health controls. Strikingly, no differential expression gene (DEG) was identified between the two groups of patients. A total of 10 overlaps (DUSP2, KLRF1, SRP19, KLRC3, CD69, SIK1, ITGA4, ID3, HSPA1A, GPR18) were obtained between DEGs of patients with KBD and patients with KBD and DF. They play important roles in metabolism, differentiation, apoptosis and bone-development. The relative abundance of 8 DEGs, i.e. FCRL6, KLRC3, CXCR4, CD93, CLK1, GPR18, SRP19 and KLRF1, were further confirmed by qRT-PCR analysis.

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.

Zinc: the Other Suspected Environmental Factor in Kashin-Beck Disease in Addition to Selenium

Kashin-Beck disease (KBD) is an endemic chronic osteochondral disease characterized by high prevalence, disability, and morbidity and is distributed from the northeast to the southwest in China, in some regions of Eastern Siberia in Russia, and in North Korea. Although the selenium deficiency etiological hypothesis for KBD has been proposed by scientists for decades, the idea that selenium deficiency is one of the most important environmental factors but not the primary and sole pathogenic factor for KBD has been widely accepted. Zn2+, which is closely involved in the synthesis of enzymes, nucleic acids, and proteins, is an essential microelement in vivo. A conundrum still exists in research on the relationship between Zn2+ and KBD due to inconsistent results, but it has been confirmed that Zn2+ can help repair metaphyseal lesions in patients with KBD, indicating that Zn2+ might play a key role in the pathogenesis of KBD, although the mechanism is unknown. The zinc-ZIP8-MTF1 axis in chondrocytes forms a catabolic cascade that promotes upregulation of the crucial effector matrix-degrading enzymes MMP3, MMP13, and ADAMTS5, thereby leading to osteoarthritis (OA) cartilage destruction. Zinc finger protein-related genes, the ZNT family, and the ZIP family of Zn2+ transporter genes have been found to be differentially expressed in KBD by high-throughput screening. Therefore, Zn2+ could play a key role in the pathogenesis of KBD.