Polymorphism of MMP-3 gene and imbalance expression of MMP-3 / TIMP-1 in articular cartilage are associated with an endemic osteochondropathy, Kashin- Beck disease.

BACKGROUND: The etiology of Kashin-Beck disease (KBD), an endemic osteochondropathy, is largely unknown. Matrix metalloproteinase-3 (MMP-3) plays a central role in the initiation and progression of cartilage destruction, however, no study has reported on the relationship between KBD and MMP-3. The objective of this study was to explore the polymorphism of MMP-3 gene and expression of MMP-3 / TIMP-1(Tissue inhibitors of matrixmetalloproteinases-1) in the pathogenesis of KBD. METHODS: Single nucleotide polymorphism (SNP) genotyping was conducted in 274 KBD cases and 248 healthy controls for eight SNPs in MMP-3 using the Sequenom MassARRAY system. Additionally, the expression of MMP-3、TIMP-1 in different layers of the articular cartilage was analyzed by immunohistochemistry for 22 KBD patients, 15 osteoarthritis (OA) patients and 21 controls. RESULTS: The results showed that six SNPs (rs520540、rs591058、rs679620、rs602128、rs639752 and rs678815) in MMP-3 were associated with the increased risk of KBD, however, after Bonferroni correction, only the SNP rs679620 in the recessive model remained significant difference (OR = 2.31, 95%CI = 1.29-4.14, P = 0.0039), homozygous for "T" allele have a risk for KBD than "C" allele carriers. Moreover, the percentages of cells expressing MMP-3 in articular cartilage were significantly higher in the KBD and OA groups than in the controls (t = 5.37 and 4.19, P<0.01). While the KBD and OA groups had lower levels of TIMP-1 positive staining compared with the controls (t = 5.23and 5.06, P<0.01). And there was no significant different between KBD and OA for the levels of MMP-3 and TIMP-1 positive staining (t = 0.05and 0.28, P>0.05). CONCLUSIONS: MMP-3 is associated with the susceptibility of KBD, and the imbalance expression of MMPs / TIMPs leading to cartilage degradation may play an important role in cartilage degradation and osteoarthritis formation in OA and KBD.

Maternal Metformin Treatment during Gestation and Lactation Improves Skeletal Muscle Development in Offspring of Rat Dams Fed High-Fat Diet.

Maternal high-fat (HF) diet is associated with offspring metabolic disorder. This study intended to determine whether maternal metformin (MT) administration during gestation and lactation prevents the effect of maternal HF diet on offspring's skeletal muscle (SM) development and metabolism. Pregnant Sprague-Dawley rats were divided into four groups according to maternal diet {CHOW (11.8% fat) or HF (60% fat)} and MT administration {control (CT) or MT (300 mg/kg/day)} during gestation and lactation: CH-CT, CH-MT, HF-CT, HF-MT. All offspring were weaned on CHOW diet. SM was collected at weaning and 18 weeks in offspring. Maternal metformin reduced plasma insulin, leptin, triglyceride and cholesterol levels in male and female offspring. Maternal metformin increased MyoD expression but decreased Ppargc1a, Drp1 and Mfn2 expression in SM of adult male and female offspring. Decreased MRF4 expression in SM, muscle dysfunction and mitochondrial vacuolization were observed in weaned HF-CT males, while maternal metformin normalized them. Maternal metformin increased AMPK phosphorylation and decreased 4E-BP1 phosphorylation in SM of male and female offspring. Our data demonstrate that maternal metformin during gestation and lactation can potentially overcome the negative effects of perinatal exposure to HF diet in offspring, by altering their myogenesis, mitochondrial biogenesis and dynamics through AMPK/mTOR pathways in SM.

MicroRNA­143 increases cell apoptosis in myelodysplastic syndrome through the Fas/FasL pathway both in vitro and in vivo.

Whilst the role of microRNA­143 (miR­143) in myelodysplastic syndrome (MDS) remains unclear, abnormally expressed microRNA­143 has been detected in many types of cancer tissues. In this study, we describe a cohort study for the verification of miR­143 expression, as well as the investigation of the molecular mechanisms of miR­143 in MDS/acute myeloid leukaemia (AML). In a series of experiments, miR­143 recombinant lentiviral vectors transformed into SKM­1 cells were either overexpressed or knocked down, and the results illustrated that the overexpression of miR­143 inhibited SKM­1 cell growth, arrested the SKM­1 cells in the G0/G1 phase, interfered with cell proliferation and induced cell apoptosis via the Fas/FasL pathway. Conversely, miR­143 knockdown induced a decrease in the apoptosis and promoted the proliferation of SKM­1 cells. Moreover, miR­143 was shown to suppress MLLT3/AF9 expression by binding to its 3'­UTR. Taken together, the findings of this study indicate that miR­143 may be a critical regulator of MDS/AML cell carcinogenesis, acting as a potent antitumour molecular target for the diagnosis or treatment of cancers associated with the abnormal expression of MLLT3/AF9, hence facilitating the development of potential therapeutics against MDS/AML.

Investigation of MMP-1 genetic polymorphisms and protein expression and their effects on the risk of Kashin-Beck disease in the northwest Chinese Han population.

BACKGROUND: The etiology of Kashin-Beck disease (KBD), an endemic osteochondropathy, is largely unknown. Matrix metalloproteinase-1 (MMP-1) plays a central role in the initiation and progression of cartilage destruction; however, no study has reported on the relationship between KBD and MMP-1. This study was to investigate the role of MMP-1 in the pathogenesis and progression of KBD. METHODS: Single nucleotide polymorphism (SNP) genotyping was conducted for 274 KBD cases and 248 healthy controls using the Sequenom MassARRAY system. Additionally, the expression of MMP-1 in the knee articular cartilage of 22 KBD patients and 21 controls was analyzed by immunohistochemistry, and the concentration of MMP-1 in their joint fluid was also measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: The results showed that two SNPs (rs470221 and rs1144396) had a weak association with increased KBD risk; however, the significance of these results did not survive Bonferroni's correction. Moreover, the percentages of cells expressing MMP-1 in each layer of cartilage were significantly higher in the KBD group than in the controls (F = 11.41-28.31, P = 0.002-0.000). The concentration of MMP-1 in KBD joint fluid was significantly higher than that in the controls (t = 9.83, P < 0.0001). CONCLUSIONS: The increased expression of MMP-1 has a potential effect on the risk of KBD in the northwest Chinese Han population. However, six selected SNPs in the MMP-1 gene might not be useful as significant markers for predicting KBD susceptibility in Chinese Han population. Therefore, future studies in the association of MMP-1 with KBD should focus on other candidate SNPs.

[Comparison of the expression profiles of cell death factors in articular cartilage between Kashin-Beck disease and osteoarthritis].

OBJECTIVE: To compare the expressions of programmed cell death 5 (PDCD5) and early growth response protein-1 (EGR-1) in the articular cartilage between Kashin-Beck disease (KBD) and primary osteoarthritis and the roles of these factors in KBD cartilage. METHODS: Cartilage specimens were collected from 10 confirmed KBD patients, 15 osteoarthritic patients and 6 healthy subjects. The expression levels of PDCD5 and EGR-1 in the cartilage were detected by immunohistochemistry staining, and the positive chondrocyte counts were recorded in the different layers of KBD and OA cartilages. RESULTS: The KBD cartilages contained a significantly higher percentage of PDCD5-positive chondrocytes in the middle layer [(41.35 ± 2.97)%] than OA cartilages [(26.48 ± 2.04)%, P=0.001] and normal cartilages [(19.02 ± 1.88)%, P=0.000] with also obvious PDCD5 over-expression in the deeper layer compared to OA (P=0.000) and normal cartilages (P=0.029), but PDCD5 expression in the superficial layer of the cartilages showed no significant difference among the 3 groups(P>0.05). The average EGR-1 positivity rate in the superficial layer of the cartilage was significantly higher in KBD patients than in OA patients (P=0.000) and healthy controls (P=0.000), but in the middle layer, its positivity rate in KBD patients was higher than that in the normal control (P=0.017) but lower than that of OA cartilage (P=0.002); EGR-1 expression in the deeper layer was comparable in KBD and OA cartilages but both was higher than that in normal cartilages. PDCD5 and EGR-1 expressions were not correlated in either KBD or normal cartilages, but were positively correlated in the superficial layer of OA cartilages. CONCLUSIONS: KBD cartilages show a significantly increased PDCD5 expression in the deeper layer and enhanced EGR-1 expression in both superficial and deeper layers, suggesting the involvement of PDCD5 and EGR-1 in the pathogenesis of KBD.

Exome sequencing and functional analysis identifies a novel mutation in EXT1 gene that causes multiple osteochondromas.

Multiple osteochondromas (MO) is an inherited skeletal disorder, and the molecular mechanism of MO remains elusive. Exome sequencing has high chromosomal coverage and accuracy, and has recently been successfully used to identify pathogenic gene mutations. In this study, exome sequencing followed by Sanger sequencing validation was first used to screen gene mutations in two representative MO patients from a Chinese family. After filtering the data from the 1000 Genome Project and the dbSNP database (build 132), the detected candidate gene mutations were further validated via Sanger sequencing of four other members of the same MO family and 200 unrelated healthy subjects. Immunohistochemisty and multiple sequence alignment were performed to evaluate the importance of the identified causal mutation. A novel frameshift mutation, c.1457insG at codon 486 of exon 6 of EXT1 gene, was identified, which truncated the glycosyltransferase domain of EXT1 gene. Multiple sequence alignment showed that codon 486 of EXT1 gene was highly conserved across various vertebrates. Immunohistochemisty demonstrated that the chondrocytes with functional EXT1 in MO were less than those in extragenetic solitary chondromas. The novel c.1457insG deleterious mutation of EXT1 gene reported in this study expands the causal mutation spectrum of MO, and may be helpful for prenatal genetic screening and early diagnosis of MO.

Mitochondrial-related gene expression profiles suggest an important role of PGC-1alpha in the compensatory mechanism of endemic dilated cardiomyopathy.

Keshan disease (KD) is an endemic dilated cardiomyopathy with unclear etiology. In this study, we compared mitochondrial-related gene expression profiles of peripheral blood mononuclear cells (PBMCs) derived from 16 KD patients and 16 normal controls in KD areas. Total RNA was isolated, amplified, labeled and hybridized to Agilent human 4 × 44k whole genome microarrays. Mitochondrial-related genes were screened out by the Third-Generation Human Mitochondria-Focused cDNA Microarray (hMitChip3). Quantitative real-time PCR, immunohistochemical and biochemical parameters related mitochondrial metabolism were conducted to validate our microarray results. In KD samples, 34 up-regulated genes (ratios ≥ 2.0) were detected by significance analysis of microarrays and ingenuity systems pathway analysis (IPA). The highest ranked molecular and cellular functions of the differentially regulated genes were closely related to amino acid metabolism, free radical scavenging, carbohydrate metabolism, and energy production. Using IPA, 40 significant pathways and four significant networks, involved mainly in apoptosis, mitochondrion dysfunction, and nuclear receptor signaling were identified. Based on our results, we suggest that PGC-1alpha regulated energy metabolism and anti-apoptosis might play an important role in the compensatory mechanism of KD. Our results may lead to the identification of potential diagnostic biomarkers for KD in PBMCs, and may help to understand the pathogenesis of KD.

The effects of mycotoxins and selenium deficiency on tissue-engineered cartilage.

OBJECTIVE: To investigate the effects of 3 mycotoxins, deoxynivalenol (DON), nivalenol (NIV) and T-2 toxin, in the presence and absence of selenium (Se) on the metabolism of tissue-engineered cartilage to mimic conditions found in Kashin-Beck disease (KBD) environments. MATERIALS AND METHODS: Chondrocytes were seeded onto bone matrix gelatin (BMG) to construct engineered cartilage. The 3 toxins were added to the culture media for 3 weeks followed by immunhistochemical analyses of collagens type II and X, aggrecan, matrix metalloproteinases 1 and 3 (MMP-1 and MMP-3), MMP inhibitors 1 and 3 (TIMP-1 and TIMP-3) and α(2) macroglobulin (α2M). RESULTS: Type II collagen was decreased while type X collagen was increased in response to DON, NIV and T-2 toxin. Aggrecan was reduced by all 3 mycotoxins. Compared with the control, the 3 toxins decreased the expression of α2M, TIMP-1 and TIMP-3, and increased the expression of MMP-1 and MMP-3. Se could partially inhibit the effects of DON, NIV and T-2 toxins. CONCLUSION: Under the low Se condition, the 3 mycotoxins produced procatabolic changes in cartilage resulting in the loss of aggrecan and type II collagen and promoted a hypertrophic phenotype of chondrocytes characterized by increasing type-X-collagen expression, enhancing the expression of MMPs, while weakening the TIMPs. Se could partially block the effects mentioned above. These results support the hypothesis that the combination of mycotoxin stress and Se deficiency would be the causative factors for KBD.

[Changes of death receptor regulator expression in the articular cartilage of patients with Kashin-Beck disease].

OBJECTIVE: To investigate the changes in the expressions of Fas-associated death domain protein (FADD) and cellular-FLICE inhibitory protein (c-FLIP) in the articular cartilage of patients with Kashin-Beck disease (KBD) and the role of these proteins in the pathogenesis of KBD. METHODS: The cartilage samples were collected from patients with established diagnosis of KBD and osteoarthritis and from healthy control subjects undergoing amputation due to traffic accidents. The expressions of Fas-associated death domain protein (FADD) and cellular-FLICE inhibitory protein (c-FLIP) in the cartilage were detected by immunohistochemistry, and the positive chondrocytes were counted in different layers of the articular cartilage under microscope. RESULTS: The positivity rates of FADD in the middle layer of articular cartilage from patients with KBD [(28.68∓2.19)%] and osteoarthritis [(35.40∓2.34)%] were significantly higher than that in normal cartilage [(10.51∓5.02)%, F=16.245, P=0.000], but the rates in the upper and deeper layers were comparable among the 3 groups (P=0.206-0.761). In KBD cartilage, FADD expression was the highest in the middle layer [(28.68∓5.38)%] followed by the deeper layer [(17.94∓8.38)%]. Compared with the healthy controls, KBD and osteoarthritis patients showed significantly higher FLIP expression in the upper layer of the cartilage (F=5.929, P=0.018) but similar expressions in middle and deeper layers. CONCLUSIONS: KBD patients have significant increased FADD expression in the middle layer but decreased FLIP expression in the upper layer of the cartilage, suggesting that the death receptor pathway and its regulators play important roles in the pathogenesis of KBD.

[Expression of Caspase-8 and Bcl-2 in the cartilage loose bodies in patients with Kashin-Beck disease].

OBJECTIVE: To investigate the role of Caspase-8 and Bcl-2 in the formation of loose bodies in Kashin-Beck disease (KBD). METHODS: Specimens of cartilage loose bodies were collected from 50 adult patients with KBD, and the samples of articular cartilage were collected from 10 healthy adults to serve as control. Avidin-biotin alkaline phosphatase immunohistochemistry was employed to examine Bcl-2 and Caspase-8 positivities in the chondrocytes in the loose bodies. RESULTS: In KBD loose bodies, the percentage of chondrocytes positive for Bcl-2 and Caspase-8 [(18.40∓8.78)% and (67.54∓12.29)%, respectively] were significantly higher than those of the control group [(12.25∓1.58)% and (24.70∓4.35)%, respectively]. Caspase-8 was found to promote chondrocyte apoptosis in the loose bodies, and this effect overrode the apoptosis-suppressing effect of Bcl-2. Bcl-2 and Caspase-8 positivities were found mainly in the deep hypertrophic chondrocytes in the cartilage or in cells adjacent to the bone tissues. CONCLUSION: KBD loose bodies contain an increased percentage of apoptotic chondrocytes positive for Bcl-2 and Caspase-8. The apoptosis-inducing effect of Caspase-8 was a dominant feature in the cartilage pathology of KBD compared to the apoptosis-suppressing effect of Bcl-2.

In vitro cartilage tissue engineering using cancellous bone matrix gelatin as a biodegradable scaffold.

In this study, we constructed tissue-engineered cartilage using allogeneic cancellous bone matrix gelatin (BMG) as a scaffold. Allogeneic BMG was prepared by sequential defatting, demineralization and denaturation. Isolated rabbit chondrocytes were seeded onto allogeneic cancellous BMG, and cell-BMG constructs were harvested after 1, 3 and 6 weeks for evaluation by hematoxylin and eosin staining for overall morphology, toluidine blue for extracellular matrix (ECM) proteoglycans, immunohistochemical staining for collagen type II and a transmission electron microscope for examining cellular microstructure on BMG. The prepared BMG was highly porous with mechanical strength adjustable by duration of demineralization and was easily trimmed for tissue repair. Cancellous BMG showed favorable porosity for cell habitation and metabolism material exchange with larger pore sizes (100-500 microm) than in cortical BMG (5-15 microm), allowing cell penetration. Cancellous BMG also showed good biocompatibility, which supported chondrocyte proliferation and sustained their differentiated phenotype in culture for up to 6 weeks. Rich and evenly distributed cartilage ECM proteoglycans and collagen type II were observed around chondrocytes on the surface and inside the pores throughout the cancellous BMG. Considering the large supply of banked bone allografts and relatively convenient preparation, our study suggests that allogeneic cancellous BMG is a promising scaffold for cartilage tissue engineering.

Effects of moniliformin and selenium on human articular cartilage metabolism and their potential relationships to the pathogenesis of Kashin-Beck disease.

OBJECTIVE: To investigate the effects of mycotoxin moniliformin (MON) on the metabolism of aggrecan and type II collagen in human chondrocytes in vitro and the relationship between MON and Kashin-Beck disease (KBD). METHODS: Human chondrocytes were isolated and cultured on bone matrix gelatin to form an artificial cartilage model in vitro with or without MON toxin. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The expression of aggrecan and type II collagen in the cartilage was determined using immunocytochemical staining. RESULTS: MON toxin inhibited chondrocyte viability in dose-dependent and time-dependent manners. MON reduced aggrecan and type II collagen syntheses in the tissue-engineered cartilage. MON also increased the expression of matrix metalloproteinase-1 (MMP-1), MMP-13, BC4 epitopes, and CD44 in cartilages. However, the expression of 3B3(-) epitopes in cartilages was inhibited by MON. Selenium partially alleviated the damage of aggrecan induced by MON toxin. CONCLUSION: MON toxin promoted the catabolism of aggrecan and type II collagen in human chondrocytes.

[Effects of selenium and/or iodine deficiency on chondrocyte apoptosis in rats].

OBJECTIVE: To explore the effects of selenium and/or iodine deficiency on chondrocyte apoptosis in articular cartilage in rats. METHODS: Forty-eight Sprague-Dawley rats were randomly divided into selenium deficiency group, iodine deficiency group, combined selenium and iodine deficiency group, and control group. Chondrocyte apoptosis was detected by terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) method, and Bcl-2 and Bax in articular cartilage were stained by immunohistochemistry in F3 generation of rats. RESULTS: In articular cartilage, the positive rate of apoptotic chondrocytes stained by TUNEL in the upper and middle zones in selenium deficiency group, iodine deficiency group, and combined selenium and iodine deficiency group (all P < 0.05) were significantly higher than that in control group. The apoptotic chondrocytes were prominent in the middle zone. The positive percentage of chondrocytes apoptosis was not significantly different among these three groups (P > 0.05). Compared with the control group, the expressions of both Bcl-2 and Bax were significantly higher in the upper and middle zone in the selenium deficiency group, iodine deficiency group, and combined selenium and iodine deficiency group (all P < 0.05); however, the expressions of Bcl-2 and Bax were not significantly different among these three groups (P > 0.05). CONCLUSION: Selenium and/or iodine deficiency may induce chondrocyte apoptosis.

[Construction of tissue-engineered cartilage by seeding chondrocytes on allogeneic cancellous bone matrix gelatin].

OBJECTIVE: To evaluate the use of cancellous bone matrix gelatin (BMG) combined with chondrocytes in constructing tissue-engineered cartilage by observing the growth, proliferation and differentiation of chondrocytes on allogeneic cancellous BMG. METHODS: The articular chondrocytes isolated from a 1-month-old rabbit were multiplied to a monolayer and seeded onto cancellous BMG to construct tissue-engineered cartilage in vitro during a period of 6 weeks. Samples were taken from the construct after 1, 2, 4, and 6 weeks of culture and evaluated by histology, immunohistochemistry and transmission electron microscopy (TEM). RESULTS: The chondrocytes excreted matrix proteoglycan and collagen on cancellous BMG. With the prolongation of the culture time, the cells proliferated in the construct and the cells in the lacunae increased. Numerous chondrocytes were present the central region of the cancellous BMG and surrounded by extracellular matrix. By 6 weeks of culture, the BMG was covered with 15-20 layers of chondrocytes and cartilaginous tissue occurred in the pores throughout the cancellous BMG. Immunohistochemical staining showed rich and evenly distributed type II collagen around the chondrocytes, and TEM revealed an ultrastructure of the chondrocyte similar to that of native chondroctyes, with abundant extracellular matrix produced around the cells. CONCLUSION: Tissue-engineered cartilage can be constructed in vitro using allogeneic cancellous BMG combined with chondrocytes. Allogeneic cancellous BMG serves as a good scaffold material for tissue-engineered cartilage to promote the growth and proliferation of the seeded chondrocytes and allows maintenance of the differentiation phenotype of the cells.

Butenolide induced cytotoxicity by disturbing the prooxidant-antioxidant balance, and antioxidants partly quench in human chondrocytes.

Butenolide (BUT), a mycotoxin produced by Fusarium species, was detected often in corns or grains from endemic Kashin-Beck disease (KBD) areas in China. In this study, we evaluated the cytotoxicity of BUT on chondrocytes and the possible toxic mechanism with the aim of understanding the pathogenesis and of directing future therapeutic interventions for KBD. Exposure of human chondrocytes and engineered cartilage to high concentration of BUT (> 1 microg/ml) resulted in significant cytotoxicity, manifested by losses in cell viability and changes in cell morphology. BUT with high concentration (> 1 microg/ml) also induced significant oxidative damage to chondrocytes in vitro evidenced by increasing both lipid peroxidation and endogenous antioxidants. Furthermore, free radical scavenging agents, such as selenium (Se), vitamin C (VC) and vitamin E (VE), partly blocked BUT-induced oxidative damage. In conclusion, this finding indicates that BUT induces cytotoxicity to human chondrocytes, and the disturbance of prooxidant-antioxidant balance may play a pivotal role in BUT-induced injuries in chondrocytes. Moreover, Se, VC or VE can quench the toxic effects of BUT to a certain extent, which will possibly direct future therapeutic interventions against KBD.

Promotion of the articular cartilage proteoglycan degradation by T-2 toxin and selenium protective effect.

OBJECTIVE: To identify the relationship between T-2 toxin and Kashin-Beck disease (KBD), the effects of T-2 toxin on aggrecan metabolism in human chondrocytes and cartilage were investigated in vitro. METHODS: Chondrocytes were isolated from human articular cartilage and cultured in vitro. Hyaluronic acid (HA), soluble CD44 (sCD44), IL-1beta and TNF-alpha levels in supernatants were measured by enzyme-linked immunosorbent assay (ELISA). CD44 content in chondrocyte membrane was determined by flow cytometry (FCM). CD44, hyaluronic acid synthetase-2 (HAS-2) and aggrecanases mRNA levels in chondrocytes were determined using reverse transcription polymerase chain reaction (RT-PCR). Immunocytochemical method was used to investigate expressions of BC-13, 3-B-3(-) and 2-B-6 epitopes in the cartilage reconstructed in vitro. RESULTS: T-2 toxin inhibited CD44, HAS-2, and aggrecan mRNA expressions, but promoted aggrecanase-2 mRNA expression. Meanwhile, CD44 expression was found to be the lowest in the chondrocytes cultured with T-2 toxin and the highest in control plus selenium group. In addition, ELISA results indicated that there were higher sCD44, IL-1beta and TNF-alpha levels in T-2 toxin group. Similarly, higher HA levels were also observed in T-2 toxin group using radioimmunoprecipitation assay (RIPA). Furthermore, using monoclonal antibodies BC-13, 3-B-3 and 2-B-6, strong positive immunostaining was found in the reconstructed cartilage cultured with T-2 toxin, whereas no positive staining or very weak staining was observed in the cartilage cultured without T-2 toxin. Selenium could partly inhibit the effects of T-2 toxin above. CONCLUSION: T-2 toxin could inhibit aggrecan synthesis, promote aggrecanases and pro-inflammatory cytokines production, and consequently induce aggrecan degradation in chondrocytes. These will perturb metabolism balance between aggrecan synthesis and degradation in cartilage, inducing aggrecan loss in the end, which may be the initiation of the cartilage degradation.

[Butenolide induces apoptosis of cultured chondrocytes: study of its mechanism].

OBJECTIVE: To observe cell apoptosis and Bcl-2 and Bax expression changes of chondrocytes induced by butenolide (BUT) and the inhibitory effect of selenium against BUT-induced chondrcyte apoptosis, to gain insights into the mechanism by which BUT induces chondrcyte apoptosis. METHODS: Cartilage tissue reestablished from human fetal articular chondrocytes in vitro were treated with BUT at the concentrations of 0.1, 1.0 and 5.0 microg/ml and with the protective factor selenium. TUNEL method was used to detect chondrocyte apoptosis, which was quantified by flow cytometry. Immunohitochemistry was performed to analyze the expression of Bcl-2 and Bax in the reestablished cartilage tissue. RESULTS: BUT exposure induced chondrocyte apoptosis, and the apoptosis rate increased with the concentration increment of BUT from 0 to 1.0 mg/ml, resulting also increased positive expression rate of Bcl-2 and Bax(P<0.05). The apoptosis rate of chondrocytes in BUT+ selenium group was significantly lower than that of BUT groups (P<0.05), as was the positivity rate of Bcl-2 and Bax expression (P<0.05). CONCLUSION: BUT induces chondrocyte apoptosis in positive relation with BUT concentration (from 0 to 1.0 mg/ml) and causes increased expressions of Bcl-2 and Bax. Selenium can inhibit the chondrocyte apoptosis induced by BUT.

[Toxic effect of butenolide on chondrocyte differentiation and the protective effect of selenium].

OBJECTIVE: To study the effect of butenolide (BUT) on cultured chondrocytes differentiation and the possible protective effects of selenium (Se). METHODS: Ex-vivo cultured chondrocytes were divided into six groups: (1) Control group (without BUT and Se); (2) Se 0.1 microg/ml control group; (3) BUT 0.1 microg/ml group; (4) BUT 1.0 microg/ml group; (5) BUT 5.0 microg/ml group; and (6) BUT 1.0 microg/ml + Se 0.1 microg/ml group. The expression of collagen II (Col II), collagen X (ColX), basic fibroblast growth factor (bFGF), and parathyroid hormone-related peptide (PTHrP) in (or around) chondrocytes in all groups were analyzed by immunohistochemistry. RESULTS: The expressions of Col II in 1.0 microg/ml BUT group and 5.0 microg/ml BUT group were significantly lower than those in the control group (P < 0.05). The expression of Col II in 1.0 microg/ml BUT + Se group were significantly higher than those in the 1.0 microg/ml BUT group and 5.0 microg/ml BUT group (P < 0.05). The expressions of bFGF and PTHrP of BUT groups were significantly higher than those in the Se and control groups (P < 0.05). No expression of ColX was observed in all groups. CONCLUSION: BUT can affect the collagen II synthesis of the chondrocytes. Selenium supplementation may play a protective role.

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

The purpose of the current study was to investigate the abnormal expression of Col X, PTHrP, TGF-beta, bFGF, and VEGF in cartilage from patients with Kashin-Beck disease (KBD) to understand the pathogenesis of chondronecrosis in KBD. Articular cartilage and growth plate cartilage collected were divided into four groups: control children (8 samples, 5 cases), KBD children (19 samples, 9 cases), control adults (8 samples, 6 cases), and KBD adults (16 samples, 15 cases). The presence of PTHrP, TGF-beta1, bFGF, VEGF, and collagen X in articular cartilage and in growth plate cartilage was analyzed by immunohistochemistry. Articular cartilage and growth plate were each divided in three zones, and the rate of positive cells was counted by light microscope for cytoplasmic and pericellular staining. Results showed that (1) in KBD children, Col X expression was lower in the deep zone of growth plate cartilage than in normal children; in articular cartilage of KBD adults, however, collagen X expression was higher in the middle zone compared to the controls; (2) staining for bFGF, PTHrP, TGF-beta1, and VEGF in KBD adult patients was prominent in the chondrocyte clusters and the eroded surface of articular cartilage, and the percentage of chondrocyte staining was significantly higher than in control samples (t = 3.64-10.34, df = 12 for children and 19 for adults, P = 0.002-0.0001); and (3) the enhanced PTHrP, TGF-beta1, and VEGF staining in the deep and middle zone of KBD articular cartilage correlated with the high incidence of chondronecrosis in the middle zone (48.5% +/- 10.2%) and deep zone (70.6% +/- 27.0%) of adult KBD cartilage. In conclusion, Col X expression was reduced in areas of chondrocyte necrosis in the deep zone of KBD articular cartilage, indicating changes in terminal chondrocyte differentiation. PTHrP, TGF-beta1, and VEGF expression was significantly altered and indicated degenerative changes in KBD cartilage, which initially resemble those occurring in osteoarthritis, but lead eventually to chondronecrosis, an event not observed in osteoarthritis.