Study on the effect of T-2 toxin combined with low nutrition diet on rat epiphyseal plate growth and development

HT-2 mycotoxin and selenium deficiency: Effects on Femur development and integrity in Young mice

Kashin-Beck Disease (KBD), an osteoarticular disorder, is potentially influenced by several factors, among which selenium deficiency and HT-2 mycotoxin exposure are considered significant. However, the combined effect of these factors on femoral development remains unclear, Conducted over eight weeks on forty-eight male mice categorized into control, selenium-deficient, and HT-2 toxin-exposed groups, including dual-exposure sets, this study comprehensively monitored body weight, bone metabolism markers, and cellular health. Employing biomechanical analysis, micro-computed tomography (micro-CT), and transmission electron microscopy (TEM), we unearthed a reduction in body weight due to HT-2 toxin alone, with selenium deficiency exacerbating these effects synergistically. Our results unveil that both factors independently affect bone metabolism, yet their confluence leads to a pronounced degradation of bone health parameters, including alterations in calcium, phosphorus, and vitamin D levels, alongside marked changes in osteoblast and osteoclast activity and bone cell structures. The notable damage to femoral cortical and trabecular architectures underscores the perilous interplay between dietary selenium absence and HT-2 toxin presence, necessitating a deeper understanding of their separate and joint effects on bone integrity. These discoveries underscore the imperative for a nuanced approach to toxicology research and public health policy, highlighting the pivotal influence of environmental and nutritional factors on skeletal well-being.

Betulinic acid attenuates T-2 toxin-induced lung injury by activating Nrf2 signaling pathway and inhibiting MAPK/NF-κB signaling pathway

T-2 toxin, a type-A trichothecene mycotoxin, exists ubiquitously in mildewed foods and feeds. Betulinic acid (BA), a pentacyclic triterpenoid derived from plants, has the effect of relieving inflammation and oxidative stress. The purpose of this study was to investigate whether BA mitigates lung impairment caused by T-2 toxin and elucidate the underlying mechanism. The results indicated that T-2 toxin triggered the inflammatory cell infiltration, morphological alterations and cell apoptosis in the lungs. It is gratifying that BA ameliorated T-2 toxin-caused lung injury. The protein expression of nuclear factor erythrocyte 2-related factor 2 (Nrf2) pathway and the markers of antioxidative capability were improved in T-2 toxin induced lung injury by BA mediated protection. Simultaneously, BA supplementation could suppress T-2 toxin-induced mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B (NF-κB)-dependent inflammatory response and mitochondrial apoptotic pathway. Therefore, T-2 toxin gave rise to pulmonary toxicity, but these changes were moderated by BA administration through regulation of the Nrf2/MAPK/NF-κB pathway, which maybe offer a viable alternative for mitigating the lung impairments caused by the mycotoxin.

Single and Combined Effects of Short-Term Selenium Deficiency and T-2 Toxin-Induced Kidney Pathological Injury Through the MMPs/TIMPs System

The single and combined effects of short-term selenium (Se) deficiency and T-2 toxin-induced kidney pathological injury through the MMPs/TIMPs system were investigated. Forty-eight rats were randomly divided into control, 10 ng/g T-2 toxin, 100 ng/g T-2 toxin, Se-deficient, 10 ng/g T-2 toxin and Se deficiency combined, and 100 ng/g T-2 toxin and Se deficiency combined groups for a 4-week intervention. The kidney Se concentration was measured to evaluate the construction of animal models of Se deficiency. Kidney tissues were analyzed by hematoxylin-eosin staining, Masson staining, and transmission electron microscope to observe the pathological changes, the severity of kidney fibrosis, and ultrastructural changes, respectively. Meanwhile, quantitative polymerase chain reaction and immunohistochemical staining were used to analyze the gene and protein expression levels of matrix metallopeptidase 2/3 (MMP2/3) and tissue inhibitor of metalloproteinase 1 (TIMP1). The results showed that short-term Se deficiency and T-2 toxin exposure can cause kidney injury through tubular degeneration and even lead to kidney fibrosis. And the combination of T-2 toxin and Se deficiency had a synergistic effect on the kidney. A dose-response effect of the T-2 toxin was also observed. At the gene and protein levels, the expression of MMP2/3 in the intervention group increased, while the expression of TIMP1 decreased compared with the control group. In conclusion, short-term Se deficiency and T-2 toxin exposure might lead to injury and even the development of fibrosis in the kidneys, and combined intervention can increase the severity with a dose-dependent trend. MMP2/3 and TIMP1 likely play a significant role in the development of kidney fibrosis.

Animal models of Kashin-Beck disease exposed to environmental risk factors: Methods and comparisons

The main etiological mechanism for Kashin-Beck disease (KBD) is deep chondrocyte necrosis induced by environmental risk factors (ERFs). The scholars have conducted several epidemiological, cellular, and animal model studies on ERFs. Gradually, four etiological hypotheses have been formed, including water of organic poisoning hypothesis represented by fulvic acid (FA), biogeochemical hypothesis represented by selenium (Se) deficiency, food mycotoxin poisoning hypothesis represented by T-2 toxin poisoning and compound etiology theory hypothesis. The animal models of KBD have been replicated based on the previous etiological hypotheses. The different species of animals (monkey, rat, dog, pig, chicken, and rabbit) were treated with different ERFs interventions, and the clinical manifestations and pathological changes of articular cartilages were observed. The animals in the experimental group were fed with endemic water, endemic grain, low nutrition, thallium sulfate, FA, Se, T-2 toxin, and iodine. The dose of thallium sulfate was 1154 μg/d; the doses range of FA were 5, 50, 150, 200, and 211 mg/kg; the doses range of Se were 0.00035, 0.00175, 0.005, 0.02, 0.031, 0.1, 0.15, 0.314, 0.5, and 10 mg/kg; the doses range of T-2 toxin were 40, 100, 200, 600, 1000, 1500, 3000, 6000, and 9000 ng/g; and the doses range of iodine were 0.04, 0.18, and 0.4-0.5 μg/g. The sample size ranged from 9 to 230 depending on the interventions and grouping; the follow-up duration ranged from 1 week to 18 months. Moreover, the methods and comparisons of different animal models of KBD had been summarized to provide a useful basis for studying the pathogenesis of KBD. In conclusion, the rhesus monkeys administrated endemic water and grain were susceptible animals to replicate KBD. The rats treated with T-2 toxin combined with Se/nutrition deficiency could be a suitable and widely used animal model.

Effect of Low Nutrition and T-2 Toxin on C28/I2 Chondrocytes Cell Line and Chondroitin Sulfate-Modifying Sulfotransferases

OBJECTIVE

To investigate the effects of low nutrition and trichothecenes-2 toxin (T-2) on human chondrocytes cell line C28/I2 and the gene expression levels of some chondroitin sulfate (CS)-modifying sulfotransferases.

METHODS

The chondrocytes were divided into 4 intervention groups: (a) control group (Dulbecco's modified Eagle's medium/Nutrient Mixture F-12 [DMEM/F-12] with fetal bovine serum [FBS]), (b) low-nutrition group (DMEM/F-12 without FBS), (c) T-2 group (DMEM/F-12 with FBS plus 20 ng/mL T-2), and (d) combined group (DMEM/F-12 without FBS plus 20 ng/mL T-2). Twenty-four hours postintervention, ultrastructural changes in the chondrocytes were observed by transmission electron microscopy (TEM). Live cell staining and methyl thiazolyl tetrazolium (MTT) assay were performed to observe cell viability. The expression of CS-modifying sulfotransferases, including carbohydrate sulfotransferase 3, 12, 13, 15 (CHST-3, CHST-12, CHST-13, and CHST-15, respectively), and uronyl 2-O-sulfotransferase (UST) were examined by quantitative real-time polymerase chain reaction (RT-qPCR) analysis.

RESULTS

The cells in the T-2 group and combined group had significantly lower live cell counts and relative survival rates than the control group. TEM pictures revealed decreased electron density of mitochondria in the low-nutrition group. The T-2 group and combined group both caused mitochondrial swelling, damage, and reduction in mitochondrial number. RT-qPCR showed a trend of altered expression of CHST and increased expression of UST genes under low-nutrition, T-2 toxin and combined interventions.

CONCLUSIONS

These results show early-stage Kashin-Beck disease chondrocyte pathophysiology, consisting of chondrocyte cell damage and compensatory upregulation of CHST and UST genes.

Endoplasmic reticulum stress pathway mediates T-2 toxin-induced chondrocyte apoptosis

T-2 toxin leads to chondrocyte apoptosis and excessive extracellular matrix degradation. The aim of this study is to investigate if endoplasmic reticulum stress (ERS) - initiated apoptosis is involved in the chondrocyte damage induced by T-2 toxin. In vivo, rats were divided into a control group, T-2 toxin 200 ng/g BW/d group, the protein levels of GRP78, CHOP, and caspase-12 were detected using immunohistochemistry in articular cartilage tissues. In vitro, C28/I2 and ATDC5 chondrocytes were treated with various concentrations of T-2 toxin. For the salubrinal protection assay, cells were pretreated with 20 μM salubrinal for 1 h, and treated with and without T-2 toxin for 24 h. The cell viability was determined using the MTT assay; and the cell apoptosis was determined using the Flow Cytometry Assay; the mRNA and protein levels of the ERS markers and ECM were determined using RT-PCR and western blotting. This study found that the expressions of GRP78, CHOP, and caspase-12 is higher in T-2 toxin group than in control group both in vivo and in vitro, and the T-2 toxin administration promoted chondrocyte apoptosis, suppressed matrix synthesis, and accelerated cellular catabolism via the ERS signaling pathway. In addition, this study found that salubrinal prevented chondrocyte injury by inhibiting ERS-mediated apoptosis via the PERK-eIF2α-ATF4-CHOP signaling pathway. Collectively, this study provides a new clue to elucidate the mechanism of T-2 toxin-induced chondrocyte damage, and presents a novel therapeutic possibility of salubrinal for Osteoarthropathy such as osteoarthritis (OA) and Kaschin-Beck disease (KBD).

Prevalence of pediatric Kashin-Beck disease in Tibet

INTRODUCTION

To estimate the prevalence of Kashin-Beck disease (KBD) among children in 2017 in Changdu of Tibet.

METHODS

We adopted a four-step recruitment to include children aged 7-12 years from seven identified historically endemic counties in Changdu. Posterior-anterior radiographs of right hand and wrist were taken and were graded at four sites (metaphysis, epiphysis, and bony end of phalanges and metacarpal and carpal bones). Two trained researchers independently read the films. Inter-rater reliability was assessed using weighted Kappa and percentage agreement. We fitted logistic regression model to examine the association of age, sex, and altitude of residential village with prevalence of KBD. We examined association between site involvement and severity of KBD using chi-square test.

RESULTS

We recruited 13,573 children (mean age = 9.3 years, 48.40% girls) with a response rate of 95.81%. The overall prevalence of radiographic KBD was 0.26%. Luolong County had the highest prevalence (0.69%), followed by Bianba (0.26%), Basu (0.24%), Mangkang (0.14%), Zuogong (0.14%), Dingqing (0.07%), and Chaya (0.00%). A higher risk of radiographic KBD was associated with older age (P for trend <0.001) and girls (OR=1.86, 95% CI: 0.94, 3.70), but not the altitude of residential village (P for trend=0.957). Metaphysis was involved in all cases of KBD while lesions in epiphysis and bony end of phalanges and metacarpals were only observed in severe cases.

CONCLUSIONS

The prevalence of radiographic KBD among children aged 7-12 years was low in Changdu compared with previous census data, suggesting the effectiveness of preventative measures. Key Points • In this study, 13,573 Tibetan children were taken X-ray films of their hands and wrists. • The prevalence of radiographic KBD among children aged 7-12 years was low in Changdu of Tibet. • The preventative measures against KBD launched by Chinese government were effective in decreasing new onsets of KBD among Tibetan children.

T-2 toxin-induced DRP-1-dependent mitophagy leads to the apoptosis of mice Leydig cells (TM3)

T-2 toxin, one member of the type A trichothecene family, induces the apoptosis of human hepatocytes (L02) and murine Leydig cells (TM3), as well as mitochondrial dysfunctions. In the present study, we attempted to investigate whether T-2 toxin toxicity is related to mitochondrial dysfunction and mitophagy. We found that T-2 toxin might induce autophagy and mitophagy in TM3 cells (TM3) in a concentration-dependent manner. In addition, T-2 toxin could induce mitochondrial dysfunction, depolarization, and fission concentration-dependently. The inducible effects of T-2 toxin on mitophagy, mitochondrial dysfunction, and cell apoptosis could all be significantly reversed by autophagy inhibitor, 3 MA. Finally, DRP-1 participated in the inducible effects of T-2 toxin on TM3 cell mitophagy, mitochondrial dysfunction, and cell apoptosis. In summary, mitophagy and mitochondrial dysfunction are essential mechanisms of the toxicity induced by T-2 toxin. Thus, our findings provide a rationale for further studies on selectively targeting mitophagy to improve mitochondrial dysfunction and to protect cells from T-2 toxin-induced toxicity.

Endemic Kashin-Beck disease: A food-sourced osteoarthropathy

OBJECTIVE

Kashin-Beck disease (KBD) is an endemic osteoarthropathy, which causes disability and heavy socioeconomic burdens. The preventive measures have been taken in the past few decades. However, recent KBD-epidemiological trend and comprehensive effect of its preventive measures need to be evaluated.

METHODS

By employing typical survey, cross-sectional survey, case-control study, intervention trial, and national surveillance, the present study summarizes comprehensive role of KBD-preventive measures.

RESULTS

The endemic KBD is distributed in a long and narrow area of the world. The latest epidemic began in the late 1950s and lasted until the end of 1980s. Epidemiology of the KBD was characterized by early-onset, gender equality, agricultural area, regional discrepancy, family aggregation, annual fluctuation, etc. Multivariate regression analysis suggested that etiology of the KBD was food-related factors such as fungal contamination of grains, selenium deficiency, imbalance of protein intake, etc. A series of intervention measures for KBD control had been implemented since 1990s, and involved more than 300 million residents. National incidences were 22.1% in 1990, 16.0% in 1995, 12.3% in 2000, 5.5% in 2005, 0.38% in 2010, and 0.18 in 2015, respectively. Although new patients were annually decreased, it still affected 22,567,600 inhabitants and there were 574,925 patients in 2016.

CONCLUSIONS

Etiology of the KBD is food-sourced. Its decreased incidence may attribute to an effective implementation of preventive measures. It is possible to eradicate KBD from the earth in the near future.

Autophagy and Apoptosis Interact to Modulate T-2 Toxin-Induced Toxicity in Liver Cells

T-2 toxin is a mycotoxin generated by Fusarium species which has been shown to be highly toxic to human and animals. T-2 toxin induces apoptosis in various tissues/organs. Apoptosis and autophagy are two closely interconnected processes, which are important for maintaining physiological homeostasis as well as pathogenesis. Here, for the first time, we demonstrated that T-2 toxins induce autophagy in human liver cells (L02). We demonstrated that T-2 toxin induce acidic vesicular organelles formation, concomitant with the alterations in p62/SQSTM1 and LC3-phosphatidylethanolamine conjugate (LC3-II) and the enhancement of the autophagic flux. Using mRFP-GFP-LC3 by lentiviral transduction, we showed T-2 toxin-mediated lysosomal fusion and the formation of autophagosomes in L02 cells. The formation of autophagosomes was further confirmed by transmission electron microcopy. While T-2 toxin induced both autophagy and apoptosis, autophagy appears to be a leading event in the response to T-2 toxin treatment, reflecting its protective role in cells against cellular damage. Activating autophagy by rapamycin (RAPA) inhibited apoptosis, while suppressing autophagy by chloroquine greatly enhanced the T-2 toxin-induced apoptosis, suggesting the crosstalk between autophagy and apoptosis. Taken together, these results indicate that autophagy plays a role in protecting cells from T-2 toxin-induced apoptosis suggesting that autophagy may be manipulated for the alleviation of toxic responses induced by T-2 toxin.

The effects of long-term low selenium diet on the expression of CHST-3, CHST-12 and UST in knee cartilage of growing rats

OBJECTIVES

To investigate the effect of low selenium diet on rat´s knee cartilage and expression of chondroitin sulfate (CS) sulfated enzymes in articular and epiphyseal-plate cartilage of rats' femur and tibia.

METHODS

Twenty-four SD rats were randomly divided into two groups with six female and six male in each group: control group (selenium 0.18 mg/kg), and low selenium group (selenium 0.02 mg/kg). After 109 days, the rats were sacrificed. The ultrastructural changes in chondrocytes of rat knee cartilage were observed by transmission electron microscopy (TEM). The morphology and pathology changes of knee cartilage were examined by hematoxylin-eosin (HE) and toluidine blue (TB) staining. The localization and expression of enzymes involved in CS sulfation, including chondroitin 6-O-sulfotransferase 1 (CHST-3), chondroitin 4-O-sulfotransferase 2 (CHST-12) and uronyl 2-O-sulfotransferase (UST) were examined by immunohistochemical staining and semi-quantitative analysis.

RESULTS

In low selenium group, ultrastructural changes of chondrocytes were observed in articular cartilage of femur (AF), articular cartilage of tibia (AT), epiphyseal-plate cartilage of femur (EF) and epiphyseal-plate cartilage of tibia (ET); however, no significant changes in chondrocytes number were observed in the above AF, AT, EF or ET. Moreover, reduced thickness of cartilage layer in AF, EF and ET was detected along with reduced staining areas of sulfated glycosaminoglycan in EF and ET in low selenium group. In addition, positive staining rate of CHST-3 was lower in AF, AT and EF, while positive staining rates of CHST-12 and UST were lower in AF, AT, EF and ET in low selenium group when compared with control group.

CONCLUSIONS

Low selenium undermines the ultrastructure of chondrocytes, inhibits the normal development of cartilage and the expression of CS sulfated enzymes.

Influence of Selenium on the Production of T-2 Toxin by Fusarium poae

The objective of this study was to investigate the effects of selenium on the production of T-2 toxin by a Fusarium poae strain cultured in a synthetic medium containing different concentrations of selenium. The T-2 toxin contents in fermentative products were evaluated by a high performance liquid chromatography (HPLC). The results showed that the production of T-2 toxin was correlated with the concentration of selenium added to the medium. In all three treatments, the addition of 1 mg/L selenium to the medium resulted in a lower toxin yield than the control (0 mg/L); the yield of the toxin began to increase when selenium concentration was 10 mg/L, while it decreased again at 20 mg/L. In summary, T-2 toxin yield in the fermentative product was affected by the addition of selenium to the medium, and a selenium concentration of 20 mg/L produced the maximum inhibitory effect of T-2 toxin yield in the fermentative product of F. poae.

Comparison of microRNA expression profiles of Kashin-Beck disease, osteoarthritis and rheumatoid arthritis

Kashin-Beck disease (KBD) is a chronic osteochondropathy with unclear pathogeny. In this study, we compared the microRNA expression profiles of 16 KBD patients, 16 osteoarthritis (OA) patients and 16 rheumatoid arthritis (RA) patients and 16 healthy controls in their blood specimens. miRNAs expression profiling was performed using Exiqon miRCURY LNATM miRNAs Array. miRNAs target genes were predicted using miRror suite. Another independent mRNA expression profile dataset of 20 KBD patients and 15 healthy controls were integrated with the miRNA expression profiles of KBD. We identified 140 differently expressed miRNAs in KBD vs.

CONTROLS

GO enrichment analysis found that hypoxia, Wnt receptor signaling pathway and vitamin B6 biosynthesis related GO terms were significantly overrepresented in the target genes of differently expressed miRNAs in KBD vs.

CONTROL

18 differently expressed common miRNAs were identified in KBD vs. Control, KBD vs. OA and KBD vs. RA. Integrating the lists of differently expressed miRNA target genes and mRNA differently expressed genes detected 6 common genes for KBD. Our results demonstrated the altered miRNAs expression profiles of KBD comparing to healthy controls, OA and RA, which provide novel clues for clarifying the mechanism of KBD.

Elevation of IGFBP2 contributes to mycotoxin T-2-induced chondrocyte injury and metabolism

Kashin-Beck disease (KBD) is an endemic degenerative osteoarthropathy. The mycotoxin of T-2 toxin is extensively accepted as a major etiological contributor to KBD. However, its function and mechanism in KBD remains unclearly elucidated. Here, T-2 toxin treatment induced chondrocyte injury in a time- and dose-dependent manner by repressing cell viability and promoting cell necrosis and apoptosis. Importantly, T-2 suppressed the transcription of type II collagen and aggrecan, as well as the release of sulphated glycosaminoglycan (sGAG). Furthermore, exposure to T-2 enhanced the transcription of matrix metalloproteinases (MMPs), including MMP-1, -2, -3 and -9. In contrast to control groups, higher expression of insulin-like growth factor binding protein 2 (IGFBP2) was observed in chondrocytes from KBD patients. Interestingly, T-2 toxin caused a dramatical elevation of IGFBP2 expression in chondrocytes. Mechanism analysis corroborated that cessation of IGFBP2 expression alleviated T-2-induced damage to chondrocytes. Simultaneously, transfection with IGFBP2 siRNA also attenuated matrix synthesis and catabolism-related gene expressions of MMPs. Together, this study validated that T-2 toxin exposure might promote the progression of KBD by inducing chondrocyte injury, suppressing matrix synthesis and accelerating cellular catabolism through IGFBP2. Therefore, this research will elucidate a new insight about how T-2 toxin participate in the pathogenesis of KBD.

The effects of T-2 toxin on the prevalence and development of Kashin-Beck disease in China: a meta-analysis and systematic review

To reveal the influence of T-2 toxin detection rate and detection amount in food samples on Kashin-Beck disease (KBD), and define a linking mechanism between T-2 toxin induced chondrocytes or cartilage damage and KBD pathological changes, seven electronic databases were searched to obtain epidemiological and experimental studies. For epidemiological studies, subgroup analyses of the positive detection rate (PDR) of the T-2 toxin and PDR of the T-2 toxin with concentrations (PDRC of T-2) >100 ng g-1 were carried out, together with a histogram of the T-2 toxin concentrations in different food types in KBD and non-KBD areas. For experimental studies, a systematic review of a variety of chondrocyte and cartilage changes and damage induced by the T-2 toxin was performed. As a result, in epidemiological studies, meta-analysis demonstrated that the T-2 toxin PDR and the overall PDRC of T-2 toxin >100 ng g-1 showed a slightly significant increase in KBD areas than that in non-KBD areas separately. From the histogram, T-2 toxin accumulation was more serious in endemic areas, especially in wheat flour samples. In experimental studies, the T-2 toxin could induce damage of chondrocytes and cartilage, and inhibit cell proliferation by promoting apoptosis and catabolism as well as intracellular injuries, which is similar to the characteristics of KBD. In conclusion, the amount of T-2 toxin detected has a more significant influence on KBD prevalence and development as compared to the T-2 toxin detection rate. Besides, the T-2 toxin induces chondrocyte and cartilage damage through apoptosis, catabolism promotion and intracellular impairment, which is similar to the KBD change.

Mycotoxins: cytotoxicity and biotransformation in animal cells

Mycotoxins are secondary metabolites produced by many microfungi. Hitherto, over 300 mycotoxins with diverse structures have been identified. They contaminate most cereals and feedstuffs, which threaten human and animal health by exerting acute, sub-acute and chronic toxicological effects, with some considered as carcinogens. Many mycotoxins at low concentrations are able to induce the expression of cytochrome P450 and other enzymes implicated in the biotransformation and metabolization of mycotoxins in vivo and in vitro. Mycotoxins and their metabolites elicit different cellular disorders and adverse effects such as oxidative stress, inhibition of translation, DNA damage and apoptosis in host cells, thus causing various kinds of cytotoxicities. In this review, we summarize the biotransformation of mycotoxins in animal cells by CYP450 isoforms and other enzymes, their altered expression under mycotoxin exposure, and recent progress in mycotoxin cytotoxicity in different cell lines. Furthermore, we try to generalize the molecular mechanisms of mycotoxin effects in human and animal cells.

T-2 toxin regulates steroid hormone secretion of rat ovarian granulosa cells through cAMP-PKA pathway

T-2 toxin is a secondary metabolite produced by Fusarium genus and is a common contaminant in food and feedstuffs of cereal origin. In porcine granulosa cells(GC), T-2 toxin has been shown to inhibit the steroidogenesis; however, the mechanism has not been well understood. Gonadotropin-stimulated steroidogenesis is regulated by the cAMP-PKA pathway. In this study, we investigated potential mechanisms for T-2 toxin-induced reproductive toxicity focusing on the critical steps of the cAMP-PKA pathway affected by T-2 toxin. We first analyzed the effects of T-2 toxin on progesterone and estrogen production in rat granulosa cells. For this purpose the granulosa cells were cultured for 48 h in 10% fetal bovine serum-containing medium followed by 24h in serum-free medium containing FSH (10 ng/ml) and androstenedione (3 ng/ml), both are required for normal steroidogenesis. Treatment of these cells with T-2 toxin dose-dependently inhibited the growth of cells and the steroid hormone production. Cellular cyclic AMP levels were dose-dependently inhibited by T-2 toxin (0, 1, 10 and 100 nM, 24 h). Furthermore, we found that although the induction of progesterone by 8-Br-cAMP (a FSH mimetic) and 22R-HC (substrate for progesterone) could both be inhibited by T-2 toxin treatment, the T-2-imposed inhibitory effects could be reversed by increasing doses of 22R-HC, while increasing 8-Br-cAMP had no effects, suggesting that T2 toxin targeted at distinct mechanisms. cAMP-stimulated steroidogenic acute regulatory protein (StAR) is a rate limiting protein in progesterone synthesis. Exposure to T2 toxin caused significant suppression of StAR expression as determined by Western blotting and semi-quantitative RT-PCR suggesting StAR is a sensitive target for T-2 toxin. Taken together, our results strongly suggest that T2 toxin inhibits steroidogenesis by suppressing cAMP-PKA pathway and StAR is a target for T-2-toxin. The antisteroidogenesis effects were observable at low T-2 dose (1 ng/ml) suggesting T-2 toxin has an endocrine disruptive effect.

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.

An animal model of Kashin-Beck disease induced by a low-nutrition diet and exposure to T-2 toxin

OBJECTIVE

We investigated the combined roles of a low-nutrition diet (low levels of protein, iodine, and selenium) and T-2 toxin in bone development and to establish an experimental animal model of Kashin-Beck disease (KBD) that reliably mimics the disease's pathological changes for further study of the pathogenesis and prevention of the disease.

METHODS

Sprague-Dawley rats were randomly divided among four groups: group A, normal diet; group B, normal diet plus T-2 toxin; group C, low-nutrition diet; and group D, low-nutrition diet plus T-2 toxin exposure. The radiographic and histopathological changes in the tibial growth zone, plate cartilage and metaphysis were examined.

RESULTS

In group D, all epiphyseal plates were blurred, thin, and irregular. Tibias were significantly shorter in group D than in groups A and B. After 4 weeks, epiphyseal plates showed chondrocyte necrosis, with the more obvious necrosis appearing in groups C and D. The positive rate of lamellar necrosis was significantly higher in group D than in groups B and A (P < 0.01). In group D, metaphyseal trabecular bone was sparse, disordered, and disrupted, and massive transverse trabecular bone appeared in the metaphysis at 12 weeks.

CONCLUSIONS

A rat model of KBD induced by a low-nutrition diet and T-2 toxin exposure demonstrated radiographic and histopathological abnormalities of the proximal epiphyseal plate and the tibial metaphysis that are very similar to the bone changes found in patients with KBD. This animal model will be helpful for further study of the pathogenesis and prevention of KBD.

Oxidant damage in Kashin-Beck disease and a rat Kashin-Beck disease model by employing T-2 toxin treatment under selenium deficient conditions

Kashin-Beck disease (KBD) is an endemic degenerative osteoarthropathy, but the mechanisms underlying its pathogenesis remains unclear. This study compares antioxidant capacity and lipid peroxidation using a novel model, in which rats were administered a selenium-deficient diet for 4 weeks prior to their exposure to T-2 toxin for 4 weeks. Changes in cell morphology and empty chondrocyte lacunae indicative of cell death, as well as cartilage proteoglycan loss in the deep zone of articular cartilage of knee joints were observed in rats with selenium-deficient diet plus T-2 toxin treatment. These changes were similar to those observed previously in KBD. The levels of thiobarbituric acid reactive substances (TBARS), indicative of lipid peroxidation in serum and cartilage, were significantly increased in all experimental groups compared to the normal diet group, while the levels of antioxidants, measured as total antioxidant capacity (T-AOC), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidases (GPX), in serum and cartilage were significantly lower than that in the normal diet group. The mRNA expression of those antioxidants in cartilage tissue was significantly reduced by T-2 toxin alone or by selenium-deficient diet plus T-2 toxin treatment. These results indicate that increasing TBARS and decreasing antioxidants in serum and cartilage by T-2 toxin treatment with a selenium-deficient nutritional status may alter oxidative stress in joint tissues and contribute to the pathological process of cartilage damage in KBD.

Histopathology of chondronecrosis development in knee articular cartilage in a rat model of Kashin-Beck disease using T-2 toxin and selenium deficiency conditions

The objective of this study is to observe pathogenic lesions of joint cartilages in rats fed with T-2 toxin under a selenium deficiency nutrition status in order to determine possible etiological factors causing Kashin-Beck disease (KBD). Sprague-Dawley rats were fed selenium-deficient or control diets for 4 weeks prior to their being exposed to T-2 toxin. Six dietary groups were formed and studied 4 weeks later, i.e., controls, selenium-deficient, low T-2 toxin, high T-2 toxin, selenium-deficient diet plus low T-2 toxin, and selenium-deficient diet plus high T-2 toxin. Selenium deficiencies were confirmed by the determination of glutathione peroxidase activity and selenium levels in serum. The morphology and pathology (chondronecrosis) of knee joint cartilage of experimental rats were observed using light microscopy and the expression of proteoglycans was determined by histochemical staining. Chondronecrosis in deep zone of articular cartilage of knee joints was seen in both the low and high T-2 toxin plus selenium-deficient diet groups, these chondronecrotic lesions being very similar to chondronecrosis observed in human KBD. However, the chondronecrosis observed in the rat epiphyseal growth plates of animals treated with T-2 toxin alone or T-2 toxin plus selenium-deficient diets were not similar to that found in human KBD. Our results indicate that the rat can be used as a suitable animal model for studying etiological factors contributing to the pathogenesis (chondronecrosis) observed in human KBD. However, those changes seen in epiphyseal growth plate differ from those seen in human KBD probably because of the absence of growth plate closure in the rat.

Effects of T-2 toxin and selenium on chondrocyte expression of matrix metalloproteinases (MMP-1, MMP-13), α2-macroglobulin (α2M) and TIMPs

T-2 toxin is regarded as an important etiological factor of Kashin-Beck disease, and supplementation of selenium-salt partly prevents Kashin-Beck disease. The present study investigated the effects of T-2 toxin on the degradation of type II collagen in human chondrocytes in vitro. Human chondrocytes were isolated and cultured on bone matrix gelatin to form an artificial cartilage model in vitro with or without T-2 toxin and selenium. Immunohistochemistry analyses showed that T-2 toxin decreased type II collagen staining and selenium appeared to prevent the decrease in type II collagen induced by T-2 toxin in engineered cartilage. Then, Western blot and RT-PCR analyses showed that an increase in MMP-13 and MMP-1 expressions, and a decrease in the expression of the general endoproteinase inhibitor (α(2)M) were induced by T-2 toxin. Gelatin reverse zymography showed that TIMP-1 and TIMP-2 levels were decreased in a dose-dependent manner after exposure of T-2 toxin. Selenium had a protective role by increasing the level of type II collagen protein through down-regulation of MMP-13 protein and mRNA expression and up-regulation of TIMP-1 and TIMP-2 expressions. These data suggest T-2 toxin induces cartilage matrix degradation by the up-regulation of MMP-13 and TIMP-1, and down-regulation of TIMP-2 and α(2)M expressions.