Down-regulated HS6ST2 in osteoarthritis and Kashin-Beck disease inhibits cell viability and influences expression of the genes relevant to aggrecan metabolism of human chondrocytes.

OBJECTIVE: Primary OA and Kashin-Beck disease (KBD) show similar pathological changes in articular cartilage. The objective was to screen differentially expressed genes between OA and normal cartilage, confirm the candidate gene expression among OA, KBD and normal cartilage, and then clarify its role in vitro. METHODS: Differentially expressed genes in OA cartilage were screened by suppression subtractive hybridization (SSH) and verified by real-time quantitative PCR (Q-PCR) analysis. Heparan sulphate 6-O-sulphotransferase 2 (HS6ST2) expression was identified by Q-PCR and immunohistochemistry. After suppressing HS6ST2 by RNA interference in C28/I2 human chondrocyte line, the effects were analysed through determining the cell viability by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), the aggrecan contents by toluidine blue staining and the mRNA expression levels of SRY-type high mobility group box 9 (SOX9), AGC1, MMP3, a disintegrin and metalloproteinase domain with thrombospondin motifs 4 (ADAMTS4) and ADAMTS5 by Q-PCR. RESULTS: HS6ST2 in the reverse subtraction library was identified as a down-regulated gene in OA and KBD at both mRNA and protein levels. The percentage of safranion O staining area was correlated positively with the percentage of HS6ST2-positive chondrocytes in OA and KBD cartilage. After HS6ST2-specific short interfering RNA (siRNA) transfection to C28/I2 cells, the cell viability was inhibited significantly, and the mRNA expression levels of SOX9 and AGC1 were reduced markedly, while MMP3 expression was increased significantly. CONCLUSION; HS6ST2 down-regulation was identified in both OA and KBD cartilage. The findings first suggest that HS6ST2 may participate in the pathogenesis of OA and KBD by influencing aggrecan metabolism.

Overexpression of heparan sulfate 6-O-sulfotransferase-2 enhances fibroblast growth factor-mediated chondrocyte growth and differentiation.

In our previous study, we reported that heparan sulfate 6-O-sulfotransferase­2 (HS6ST2) plays an important role in the cartilage of patients with osteoarthritis and Kashin-Beck disease and that it regulates aggrecan (Acan) metabolism and the viability of chondrocytes. However, its role in chondrocyte differentiation remains poorly understood. In the present study, we aimed to investigate the role of HS6ST2 in chondrocyte differentiation in vitro using mouse prechondrocytic cells. We found that the overexpression or silencing of HS6ST2 significantly enhanced or abrogated the effects of fibroblast growth factor (FGF)­2 on chondrocyte growth, respectively. We found that the overexpression of HS6ST2 significantly induced the expression of Acan as well as the amount of total proteoglycans in the prechondrocytic cells in the presence of FGF­2, whereas the silencing of HS6ST2 caused the opposite effect. Furthermore, the expresssion of FGF­2­induced sex­determining region Y­type high mobility group box protein 9 (SOX9), a major transcription factor for chondrocyte proliferation and differentiation, was also enhanced or blocked by HS6ST2 overexpression or HS6ST2 knockdown, respectively. Additionally, Wnt/ß­catenin signaling, which inhibited chondrocyte proliferation and differentiation, was suppressed by HS6ST2. Taken together, these data suggest that HS6ST2 plays an important role in regulating chondrocyte growth and differentiation by modulating FGF­2 signaling, thus indicating that it may be a potential and valuable molecular target for the treatment of skeletal dysplasias, such as dwarfism.

[The incidence of dementia among elderly people in Xi' an, China].

OBJECTIVE: To explore the incidence of dementia among elderly people in Xi'an and its related risk factors. METHODS: Subjects that had been studied on the prevalence of dementia were follow-up, and the incidence of dementia, Alzheimer disease (AD) , and vascular dementia (VD) were counted by person-years. The clinical diagnosis on dementia,AD and VD were based upon the 3rd Edition of Diagnostic and Statistical of Manual of Mental Disorder, Revised version (DSM-III-R) and NINCDS-ADRDA criteria. RESULTS: 2197 subjects of non-dementia being identified in 1998, were re-surveyed in 2001. Out of them, 47 new cases of dementia including 37 cases of AD and 8 cases of VD were identified, with an annual incidence rates of dementia, AD and VD as 0.68%, 0.54% and 0.12% among those of 55 years and over and 0.89%, 0.69% and 0.17% in 65 years and over, respectively. Analysis from single factor logistic regression showed that age and education but not gender were closely related to the occurrence of AD. On the contrary, age, hypertension and stroke were closely related to the occurrence of VD. CONCLUSION: The incidence of dementia in the "Xi' an cohort" was similar to that being reported from other countries. AD and VD were an age-related diseases but education seemed to have had great protective effect while lack of formal education served as risk factor to AD.