血管成形术后血管外膜α-SMA、PCNA和OPN表达变化及意义

目的探讨大鼠胸主动脉血管成形术后血管平滑肌肌动蛋白(α-SMA)、增殖细胞核抗原(PCNA)和骨桥蛋白(OPN)表达的变化与血管外膜增殖的关系。方法6周龄健康、清洁纯系雄性SD(Sprague-Dawley)大鼠32只,体质量为(200±20)g;随机将其分为实验组和对照组,实验组大鼠用6 F人冠状动脉快速交换球囊扩张及剥脱胸腹主动脉内膜,对照组大鼠行胸腹主动脉假手术处理,术后第2周取胸主动脉,进行α-SMA、PCNA及OPN免疫组织化学检查;第6周取胸主动脉做组织形态学检查,并进行对比分析。结果对照组胸主动脉见α-SMA外膜和内膜极少量表达及中膜均匀表达;PCNA外膜和内膜极微量表达及外膜OPN阳性表达。实验组胸主动脉外膜和新生内膜α-SMA、PCNA及OPN阳性表达较对照组明显增强,而中膜α-SMA表达明显减弱。实验组胸主动脉外膜厚度和细胞数量及细胞增殖指数较对照组明显增加(P<0.05)。结论血管成形术后,血管外膜成纤维细胞被激活、增殖,向肌成纤维细胞表型转变,外膜OPN表达增多,外膜增厚,参与血管收缩性重塑。     

肿瘤坏死因子-α与骨桥蛋白在类风湿关节炎滑膜成纤维细胞中表达的相互影响及其信号转导途径

目的分析肿瘤坏死因子-α(TNF-α)和骨桥蛋白(OPN)在类风湿关节炎滑膜成纤维细胞中表达的相互影响及可能的信号转导途径。方法采用牛源性Ⅱ型胶原配合不完全弗氏佐剂制造胶原诱导性关节炎(CIA)模型,取正常对照组和模型组膝关节滑膜,胶原酶消化法分别培养滑膜成纤维细胞(SFs),分成正常对照组、模型组、模型组+脂多糖(LPS)、模型组+LPS+p38途径抑制剂(SB203580),观察SFs中OPN mRNA的变化,分析TNF-α与OPN表达的相互影响及可能的信号转导途径。结果模型组细胞加入LPS刺激后OPN mRNA表达较模型组明显增多(P<0.01),予SB203580后,OPNmRNA的表达显著减少,4组间比较差异显著(P<0.01)。结论 TNF-α可诱导OPN的表达,这一过程可能是通过p38丝裂原活化蛋白激酶(p38MAPK)信号转导途径而实现的。     

Plasma osteopontin as a biomarker of prostate cancer aggression: relationship to risk category and treatment response

Background:

High plasma osteopontin (OPN) has been linked to tumour hypoxia, metastasis, and poor prognosis. This study aims to assess whether plasma osteopontin was a biomarker of increasing progression within prostate cancer (PCa) prognostic groups and whether it reflected treatment response to local and systemic therapies.

Methods:

Baseline OPN was determined in men with localised (n=199), locally recurrent (n=9) and castrate-resistant, metastatic PCa (CRPC-MET; n=37). Receiver-operating curves (ROC) were generated to describe the accuracy of OPN for distinguishing between localised risk groups or localised vs metastatic disease. We also measured OPN pre- and posttreatment, following radical prostatectomy, external beam radiotherapy (EBRT), androgen deprivation (AD) or taxane-based chemotherapy.

Results:

The CRPC-MET patients had increased baseline values (mean 219; 56–513 ng ml⁻¹; P<0.0001) compared with the localised, non-metastatic group (mean 72; 12–438 ng ml⁻¹). The area under the ROC to differentiate localised vs metastatic disease was improved when OPN was added to prostate-specific antigen (PSA) (0.943–0.969). Osteopontin neither distinguished high-risk PCa from other localised PCa nor correlated with serum PSA at baseline. Osteopontin levels reduced in low-risk patients after radical prostatectomy (P=0.005) and in CRPC-MET patients after chemotherapy (P=0.027), but not after EBRT or AD.

Conclusion:

Plasma OPN is as good as PSA at predicting treatment response in CRPC-MET patients after chemotherapy. Our data do not support the use of plasma OPN as a biomarker of increasing tumour burden within localised PCa.     

Effect of human osteopontin on proliferation, transmigration and expression of MMP-2 and MMP-9 in osteosarcoma cells

Background To explore the effect of human osteopontin (hOPN) on the proliferation, transmigration and expression of matrix metallproteinase-2 (MMP-2) and matrix metallproteinase-9 (MMP-9) in osteosarcoma (OS) cells in vitro.Methods The prokaryotic-expression vector of hOPN was produced, hOPN was then subcloned into E. coli BL21 (DE3) cells and purified with ProBond^TM Columns. The proliferation, cell cycle and the expression of cycUn A in OS cells were investigated by using MTT assay, flow cytometry and Western blot respectively. The transmigration of OS cells was checked by using transwell cell culture chamber.The micro-pore-filter-membrane system was used to study the chemiotaxis of hOPN to OS cells. The levels of total protein were examined according to Coomassie Brilliant Blue manuals. The expression of MMP-2 and MMP-9 were evaluated by detecting the volume of degradation of gelatin on SDS-PAGE gel.Results The prokaryotic-expression vector of hOPN and purified hOPN protein were achieved hOPN promoted OS cells proliferation in a dose-dependent manner, and stimulated cyclin A expression in OS cells to accelerate cell division cycle, hOPN facilitated the trans-membrane migration of OS cells.hOPN also enhanced the secretion of MMP-2 and MMP-9 in OS cells.Conclusion hOPN could stimulate cyclin A expression in OS cells, hOPN has chemiotaxis to OS cells and increases their transmigration, hOPN enhances the secretion of MMP-2 and MMP-9 in OS cells.     

Calcification and osteopontin localization in the peritoneum of patients on long-term continuous ambulatory peritoneal dialysis therapy.

BACKGROUND: Peritoneal calcification is an uncommon complication of continuous ambulatory peritoneal dialysis (CAPD), which is mainly observed in patients on long-term therapy. Although some asymptomatic patients must have microscopic calcification in their peritoneum, little information on this topic has been published. Recent studies have revealed active participation of adhesive/chemotactic protein osteopontin (OPN) in dystrophic calcification. METHODS: Peritoneal tissue was obtained by biopsy or at autopsy from 18 CAPD patients (median duration, 122 months), 5 control haemodialysis (HD) patients, and 3 pre-CAPD patients. The distribution of calcium deposits and OPN protein was determined by von Kossa staining and immunohistochemistry, respectively. Smooth muscle cells and macrophages were identified with anti-alpha smooth muscle actin (alpha-SMA) and anti-CD68 antibodies. RESULTS: Calcium deposits with various configurations were observed in specimens from 12 of the 18 CAPD patients. They included massive calcification facing the peritoneal cavity, scattered granular or crystalloid deposits in the submesothelial stroma, and oval-shaped deposits formed within hyalinized vasa. Most were present in highly sclerosed areas and accompanied by extracellular OPN precipitation. Cytoplasmic OPN was detected in infiltrating leukocytes, granulation tissue cells, fibroblast-like cells and mast cells. Computerized tomography examination also detected peritoneal calcification in seven of the CAPD patients. No calcium deposits or OPN staining was detected in control specimens. CONCLUSIONS:The results of our study suggest that microscopic peritoneal calcification is frequent in patients on CAPD for more than 10 years. Myofibroblast infiltration, OPN expression, calcium deposition, and associated OPN precipitation seem to be components of the peritoneal changes in such patients.     

Focal Adhesion Kinase Is Important for Fluid Shear Stress‐Induced Mechanotransduction in Osteoblasts

Mechanical loading of bone is important for maintenance of bone mass and structural stability of the skeleton. When bone is mechanically loaded, movement of fluid within the spaces surrounding bone cells generates fluid shear stress (FSS) that stimulates osteoblasts, resulting in enhanced anabolic activity. The mechanisms by which osteoblasts convert the external stimulation of FSS into biochemical changes, a process known as mechanotransduction, remain poorly understood. Focal adhesions are prime candidates for transducing external stimuli. Focal adhesion kinase (FAK), a nonreceptor tyrosine kinase found in focal adhesions, may play a key role in mechanotransduction, although its function has not been directly examined in osteoblasts. We examined the role of FAK in osteoblast mechanotransduction using short interfering RNA (siRNA), overexpression of a dominant negative FAK, and FAK^?/? osteoblasts to disrupt FAK function in calvarial osteoblasts. Osteoblasts were subjected to varying periods oscillatory fluid flow (OFF) from 5 min to 4 h, and several physiologically important readouts of mechanotransduction were analyzed including: extracellular signal‐related kinase 1/2 phosphorylation, upregulation of c‐fos, cyclooxygenase‐2, and osteopontin, and release of prostaglandin E₂. Osteoblasts with disrupted FAK signaling exhibited severely impaired mechanical responses in all endpoints examined. These data indicate the importance of FAK for both short and long periods of FSS‐induced mechanotransduction in osteoblasts.     

Altered osteoclast development and function in osteopontin deficient mice

The role of osteopontin in bone resorption was elucidated by studies of mice with knock out of the osteopontin gene generated by a different approach compared to previous models. Thus, a targeting vector with the promoter region as well as exons 1, 2, and 3 of the osteopontin gene was replaced by a loxP‐flanked Neo‐TK cassette, and this cassette was eliminated through transient expression of Cre recombinase. The recombined ES cells were used to create mice lacking expression of the osteopontin gene. Tissues from these mice were subjected structural and molecular analyses including morphometry and proteomics. The bone of the null mice contained no osteopontin but showed no significant alterations with regard to other bone proteins. The bone volume was normal in young null animals but in the lower metaphysis, the volume and number of osteoclasts were increased. Notably, the volume and length of the osteoclast ruffled border was several folds lower, indicating a lower resorptive capacity. The null mice did not develop the bone loss characteristic for osteoporosis demonstrated in old wild‐type female animals. This quantitative study demonstrates a bone phenotype in the osteopontin null mice of all ages. The data provides further evidence for a role of osteopontin in osteoclast activity. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:721–728, 2008     

Osteopontin regulates adhesion of calcium oxalate crystals to renal epithelial cells.

BACKGROUND: The association of calcium crystals with renal tubular cells is an important factor during the formation of urinary stones. We previously reported the strong expression of osteopontin (OPN) on renal tubular cells in the stone-forming kidney, suggesting that OPN plays a role in the crystal-cell interaction. In the present study, we examined the biological consequences of inhibiting OPN expression at the translational level on the formation and adhesion of crystals. METHODS: We synthesized antisense OPN expression vector (pTet-OPNas) using the tetracycline-regulated expression system. The pTet-OPNas was constructed using a mouse OPN cDNA sequence in an inverted (antisense) orientation. Two clones (NRK-52E/ASs) were identified by transfection of pTet-OPNas into NRK-52E cells and they showed a marked reduction of OPN synthesis in the absence of tetracycline. Calcium oxalate (CaOx) crystal suspension was spread homogeneously on top of the NRK-52E cells. After incubation, the association of CaOx crystals and cells was visualized by scanning electron microscopy. RESULTS: Intact NRK-52E cells, NRK-52E cells transfected with empty vector and tetracycline-treated antisense clones (NRK-52E/ASs), under identical conditions, were associated with CaOx crystals. In contrast, the expression of antisense OPN prevented the association of CaOx crystals with NRK-52E cells. CONCLUSIONS: Osteopontin plays a crucial role in the adhesion process of CaOx crystals to renal tubular cells in stone formation.     

Implication of Expression of Osteopontin and Its Receptor Integrin αvβ3 in the Placenta in the Development of Preeclampsia

To investigate the expression of osteopontin （OPN） and its receptor integrin αvβ3 in the placental tissue from pregnant women complicated with preeclampsia, the expression of OPN and αvβ3 in the placenta of the pregnant women with preeclampsia and healthy pregnant women was detected by immunohistochemistry, Western blotting and RT-PCR. Our results showed that OPN and αvβ3 protein were expressed in the placenta from normal pregnant woman and those with preeclampsia. OPN was located in the placental syncytiotrophoblasts and the cytoplasm of capillary endothelial cells and integrin αvβ3 was mainly expressed on the surface of trophoblast cells. Expression of OPN and integrin αvβ3 in the placental tissue from preeclampsia subjects was significantly lower than that from the control group （P〈0.05）. Compared with the control group, expression of OPN in the placental tissue from preeclampsia group was significantly lower （P〈0.05） but there was no significant difference in the expression of αv and β3 between the preeclampsia group and the controls. It is concluded that OPN and its receptor integrin αvβ3 may be involved in the pathogenesis of preeclampsia.