The Mechanism of Cordyceps sinensis and Strontium in Prevention of Osteoporosis in Rats

The effects of Cordyceps sinensis (Caterpillar fungus) and strontium ranelate on ovariectomized osteopenic rats was studied in this paper. After the rats were treated orally with C. sinensis, strontium, and C. sinensis rich in strontium ranelate (CSS) respectively, serum alkaline phosphatase (ALP), tartarate-resistant acid phosphatase (TRAP), serum osteocalcin (OC), homocysteine, C-terminal crosslinked telopeptides of collagen type I (CTX), estradiol, and interferon-gamma (IFN-γ) level were examined. The beneficial effects of CSS on improvement of osteoporosis in rats were attributable mainly to decrease ALP activity, TRAP activity, CTX level, and IFN-γ level. At the same time, CSS also increase the OC and estradiol level in ovariectomized osteopenic rats. This study demonstrates the value of C. sinensis rich in strontium ranelate in the management of postmenopausal osteoporosis in humans.     

A cross-sectional study on biochemical parameters of bone turnover and vitamin d metabolites in healthy dutch children and young adults

AIM: To provide reference data of biochemical markers of bone turnover and vitamin D metabolites for children and young adults. METHODS: Blood samples were taken from 176 healthy Dutch children and young adults (age range 7.6-25.3 years) to assess serum calcium, alkaline phosphatase, inorganic phosphate, osteocalcin, collagen type I cross-linked N-telopeptide, N-terminal propeptide of type I procollagen, 25-hydroxyvitamin D3, and 1,25-dihydroxyvitamin D3 levels. Cross-linked telopeptide of type I collagen and carboxy-terminal propeptide of type I procollagen were assessed in 286 subjects (age range 1.4-25.3 years). RESULTS: Calcium and vitamin D levels were independent of age. The peak concentrations for collagen type I cross-linked N-telopeptide, cross-linked telopeptide of type I collagen, carboxy-terminal propeptide of type I procollagen, N-terminal propeptide of type I procollagen, alkaline phosphatase, and osteocalcin were found during puberty, in girls approximately 2.5 years earlier than in boys. Strong correlations were found between the markers of bone turnover, while no correlation was found between the markers of bone turnover and bone mineral density measured by dual-energy X-ray absorptiometry. CONCLUSIONS: Single measurements of bone markers cannot predict bone density. Reference data according to gender, age, and Tanner stage are given which allow calculating standard deviation scores adjusted for age and gender.     

The effect of long-term glucocorticoids on bone metabolism in systemic lupus erythematosus patients: the prevalence of its anti-inflammatory action upon bone resorption

The study was made to evaluate bone turnover in systemic lupus erythematosus (SLE) patients undergoing long-term glucocorticoid therapy. Thirty-eight female patients with established SLE were compared with a control group consisting from 160 age-matched healthy women. Serum concentrations of proinflammatory cytokines: interleukin-1alpha, interleukin-6, tumor necrosis factor-alpha, granulocyte-macrophage colony stimulating factor (GM-CSF) and some biochemical markers of osteoporosis (osteocalcin, total and bone alkaline phosphatase, procollagen type I carboxyterminal propeptide, carboxyterminal telopeptides of type I collagen--CTx) were measured. Additionally, morning urine excretions of deoxypyridinoline and calcium/creatinin ratios were determined. The forearm densitometry (DXA) was performed in all patients. Bone mineral content (BMC) and bone mineral density (BMD) in the SLE group was not significantly different from the controls, and no relationship was found between the glucocorticoid exposure and the BMC/BMD. However, biochemical markers of bone resorption--CTx and calcium/creatinin ratio--were significantly increased in the patient group. Our results suggest that BMD/BMC is preserved in glucocorticoid-treated SLE patients despite accelerated bone turnover.     

Biomarkers for osteoporosis management: utility in diagnosis, fracture risk prediction and therapy monitoring

Osteoporosis is a systemic disease characterized by low bone mass and microarchitectural deterioration of bone tissue, resulting in an increased risk of fracture. While the level of bone mass can be estimated by measuring bone mineral density (BMD) using dual X-ray absorptiometry (DXA), its measurement does not capture all the risk factors for fracture. Quantitative changes in skeletal turnover can be assessed easily and non-invasively by the measurement of serum and urinary biochemical markers; the most sensitive markers include serum osteocalcin, bone specific alkaline phosphatase, the N-terminal propeptide of type I collagen for bone formation, and the crosslinked C- (CTX) and N- (NTX) telopeptides of type I collagen for bone resorption. Advances in our knowledge of bone matrix biochemistry, most notably of post-translational modifications in type I collagen, are likely to lead to the development of new biochemical markers that reflect changes in the material property of bone, an important determinant of bone strength. Among those, the measurement of the urinary ratio of native (alpha) to isomerized (beta) CTX - an index of bone matrix maturation - has been shown to be predictive of fracture risk independently of BMD and bone turnover.In postmenopausal osteoporosis, levels of bone resorption markers above the upper limit of the premenopausal range are associated with an increased risk of hip, vertebral, and nonvertebral fracture, independent of BMD. Therefore, the combined use of BMD measurement and biochemical markers is helpful in risk assessment, especially in those women who are not identified as at risk by BMD measurement alone. Levels of bone markers decrease rapidly with antiresorptive therapies, and the levels reached after 3-6 months of therapy have been shown to be more strongly associated with fracture outcome than changes in BMD. Preliminary studies indicate that monitoring changes of bone formation markers could also be useful to monitor anabolic therapies, including intermittent parathyroid hormone administration and, possibly, to improve adherence to treatment. Thus, repeated measurements of bone markers during therapy may help improve the management of osteoporosis in patients.     

重组人骨保护素对激素性股骨头坏死患者骨密度及髋关节Harris评分 的影响

目的:探讨重组人骨保护素对于激素性股骨头坏死患者的骨密度和髋关节Harris评分的影响。方法:选取我院骨科已经确诊的110例激素性股骨头坏死患者,随机分为对照组(给予仙灵骨葆胶囊)和观察组(给予仙灵骨葆胶囊和重组人骨保护素),连续治疗4周,检测并比较两组患者治疗前后的骨密度、髋关节Harris评分、血清抗酒石酸酸性磷酸酶(TRAP)、Ⅱ型胶原羧基端端肽(CTX-Ⅱ)水平以及复发率变化。结果:与对照组相比较,观察组患者腰椎骨和股骨近端的骨密度较高平(P0.05);髋关节Harris评分总有效率(92.73%)显著高于对照组(76.36%)(P0.05)。两组血清TRAP及CTX-Ⅱ水平显著低于治疗前,且试验组血清TRAP及CTX-Ⅱ水平显著低于对照组(P0.05),与对照组相比,观察组复发率较低(P0.05)。结论:重组人骨保护素能够抑制骨吸收,提高骨密度和强度,改善髋关节功能,有望成为激素性股骨头坏死的新型治疗方法。     

Hormone replacement therapy,calcium and vitamin D<Subscript>3</Subscript> versus calcium and vitamin D<Subscript>3</Subscript>alone decreases markers of cartilage and bone metabolism in rheumatoid arthritis: a randomized controlled trial [ISRCTN46523456]

This study aimed to evaluate the effects of hormone replacement therapy (HRT), known to prevent osteoporosis and fractures, on markers of bone and cartilage metabolism. Furthermore, we assessed whether changes in these markers corresponded to alterations in bone mineral density and radiographic joint destructions in postmenopausal women with rheumatoid arthritis. Eighty-eight women were randomized to receive HRT, calcium, and vitamin D3, or calcium and vitamin D3 alone, for 2 years. Bone turnover was studied by analyzing serum levels of C-terminal telopeptide fragments of type I collagen (CTX-I), C-terminal telopeptide of type I collagen (ICTP), bone sialoprotein, and C-terminal propeptide of type I procollagen (PICP) and cartilage turnover by urinary levels of collagen type II C-telopeptide degradation fragments (CTX-II) and cartilage oligomeric matrix protein (COMP) in serum. Treatment with HRT resulted in decrease in CTX-I (P < 0.001), ICTP (P < 0.001), PICP (P < 0.05), COMP (P < 0.01), and CTX-II (P < 0.05) at 2 years. Reductions in CTX-I, ICTP, and PICP were associated with improved bone mineral density. Of the markers tested, CTX-I reflected bone turnover most sensitively; it was reduced by 53 +/- 6% in the patients receiving HRT. Baseline ICTP (P < 0.001), CTX-II (P < 0.01), and COMP (P < 0.05) correlated with the Larsen score. We suggest that biochemical markers of bone and cartilage turnover may provide a useful tool for assessing novel treatment modalities in arthritis, concerning both joint protection and prevention of osteoporosis.     

The beneficial effect of OST-6 (OsteoCare), a herbomineral formulation, in experimental osteoporosis.

OST-6 (OsteoCare), a herbomineral formulation, was evaluated for its inhibitory effect on the progress of bone loss induced by ovariectomy in rats. Ovariectomized (Ovx) rats were administered with OST-6 at 250 and 500 mg/kg b.wt., orally daily for 90 days. On 91st day, ovariectomized rats showed reduced bone mineral content and increased serum alkaline phosphatase levels, excretion of urinary calcium and pyridinium cross-links levels. Histologically, bone sections revealed narrowed and disappearance of trabeculae and widened medullary spaces. The total numbers of Tartrate-resistant acid phosphatase (TRAP) positive cells were significantly increased both in-vivo and in-vitro methods. OST-6, at a dose of 500 mg/kg, significantly improved bone mineral contents, serum alkaline phosphatase levels, reduced the elevated urinary calcium and pyridinium cross-links excretion, number of TRAP positive cells and reversal of the above mentioned histological features. These results indicate the usefulness of OST-6 in the management of osteoporosis in a natural way through herbal resources.     

High phosphorus diet changes phosphorus metabolism regardless of PTH action in rats

In this study, we ascertained whether the parathyroid hormone (PTH) dominantly regulated the effects of high phosphorus (P) intakes on urinary excretion of P and bone metabolism in rats. To maintain serum PTH level equally, parathyroidectomy (PTX) and sham-operated rats were constantly exposed to rPTH(1-34) and fed both control (0.3% P) and high P (1.2% P) diet for 7 days, respectively. Urinary excretions of P and C-terminal telopeptides of type I collagen were significantly increased in both PTX and sham rats by the high P diet. These results suggest that high P diet increased urinary P excretion while promoting bone resorption regardless of PTH-dependent regulation.     

Beta-CTX and ICTP act as indicators of skeletal metastasis status in male patients with non-small cell lung cancer

Bone metastasis is common in lung cancer patients and associated with reduced quality of life and reduced overall and median survival, so the early detection of bone metastasis and monitoring of its status is very important for clinicians. Serum bone-specific alkaline phosphatase (BAP), osteocalcin (OC), beta isomer of C-terminal telopeptide of type I collagen (beta-CTX) and cross-linked C-terminal telopeptide of type I collagen (ICTP) were compared with regard to their usefulness as indicators of bone metastasis in lung cancer. The serum concentrations of the 4 markers were measured by commercially available tests in 96 male patients with non-small cell lung cancer and 30 male patients with other pulmonary diseases. The levels of both a-CTX and ICTP were significantly higher in 61 lung cancer patients with bone metastases than in 35 lung cancer patients without bone metastases (both p<0.001), and significantly correlated with the extent of bone disease. Although ICTP had a better sensitivity and accuracy than beta-CTX (75.4% vs 65.6% and 72.9% vs 68.8%, respectively), they had a similar area under the receiver operating characteristic curve (0.85 vs 0.83). These results support the use of beta-CTX and ICTP as an adjunct tool for the diagnosis and screening of bone metastasis in lung cancer.     

中等强度跑台运动预防去卵巢大鼠骨质疏松

目的观察中等强度跑台运动对去卵巢大鼠骨质疏松的预防作用。方法将30只3月龄未经产雌性SD大鼠随机分为假手术、去卵巢静止和去卵巢运动三个组。去卵巢运动组每周进行4次时间45min、速度18m/min、坡度5°的跑台训练。实验结束时,检测血清雌二醇（E2）、碱性磷酸酶（ALP）、抗酒石酸酸性磷酸酶（TRAP）和骨钙素（BGP）水平以及右侧游离股骨和胫骨的骨密度（BMD）和骨矿物含量（BMC）;同时观察左侧股骨远端和胫骨近端组织形态学变化。结果与假手术组比较,去卵巢静止组大鼠血清ALP活性和BGP含量显著升高,血清TRAP活性和E2含量显著下降,股骨近段和远端以及胫骨近端BMD和BMC显著下降,股骨远端和胫骨近端骨小梁断裂增加、数目减少;与去卵巢静止组比较,去卵巢运动组大鼠血清E2和BGP含量显著上升,股骨三个部位以及胫骨近端BMD和BMC显著增加,股骨远端和胫骨近端骨小梁断裂减少、数目增加。结论中等强度跑台运动能增加去卵巢大鼠血清E2和BGP含量,改善去卵巢大鼠骨组织学结构。     

A role for osteocalcin in osteoclast differentiation

Specific cellular interactions with components of the extracellular matrix can influence cellular differentiation and development of many tissues. The extracellular matrix of bone is composed of organic constituents and a solid phase of calcium and inorganic phosphate (apatite). When implanted subcutaneously in rats, particles of bone matrix (BPs) recruit progenitors that differentiate into multinucleated cells with osteoclastic features. Because BPs deficient in osteocalcin, a bone matrix protein, were less efficient at promoting osteoclast formation than were normal BPs, we directly examined the influence of osteocalcin on osteoclast differentiation. We evaluated tissue responses to particles of synthetic crystalline apatite alone (Ap), having many of the features of native apatite of mature bone, or to apatite prepared with osteocalcin (Ap/OC), bovine serum albumin (Ap/BSA) or rat bone collagen (Ap/Col). Twelve days after subcutaneous implantation in normal rats, Ap, Ap/BSA, and Ap/Col particles generated a mild foreign body reaction with multinucleated cells in direct contact with the particles; these cells were negative for tartrate-resistant acid phosphatase (TRAP) activity and lacked ruffled borders. In contrast, Ap particles containing approximately 0.1% osteocalcin were partially resorbed and they generated more multinucleated cells that were TRAP-positive, were immunoreactive with an antibody against tartrate-resistant purple acid phosphatase, and displayed ultrastructural features of active osteoclasts including ruffled borders and clear zones. These data support the hypothesis that osteocalcin may function as a matrix signal in the recruitment and differentiation of bone-resorbing cells.     

No association between the vitamin D pathway gene polymorphisms and bone biomarkers response to calcium and low dose calcitriol supplementation in postmenopausal Chinese women: a one-year prospective study

Abstract

Introduction: The aim of the study was to explore the association between the vitamin D pathway gene variations and the bone biomarkers response to calcium and low dose calcitriol supplementation in postmenopausal Chinese women.

Methods: A total of 110 healthy postmenopausal Chinese women (61.51?±?6.93?years) were enrolled. The participants were supplemented with calcium (600?mg/d) and calcitriol (0.25?μg/d), for 1?year. Four biomarkers, serum levels of beta C-terminal cross-linked telopeptides of type I collagen (β-CTX), amino-terminal propeptide of type I collagen (P1NP), parathyroid hormone (PTH) and 25-hydroxyvitamin D [25(OH)D] were measured at baseline and 12-month follow-up. Multivariate regression models were established to explore the statistical association between the change rate of the four biomarkers and 15?key genes within the vitamin D metabolic pathway.

Results: This exclusion process left 98 participants for analysis. Serum levels of P1NP, β-CTX and PTH were significantly decreased at the 12-month follow-up (all p?<?0.05). Serum 25(OH)D level had no significant change (p?>?0.05). No association was found between the vitamin D pathway gene polymorphisms and bone biomarkers response to calcium and low dose calcitriol supplementation.

Conclusions: Genetic background of postmenopausal Chinese women might not influence supplemental response of the biomarkers to calcium and low dose calcitriol.     

Dietary Silicon Intake of Korean Young Adult Males and Its Relation to their Bone Status

Accumulated data suggests a positive effect of silicon on bone health; however, limited research exists on the silicon content of foods. To further the understanding of the relationship between dietary silicon intake and bone health, a food composition database of commonly consumed foods in Korea is required. For quantitative data on the intake levels of silicon, we analyzed the silicon content of 365 food items commonly consumed in Korea using inductively coupled plasma—atomic emission spectrometry following microwave-assisted digestion. To investigate the dietary silicon intake status and to examine the potential role of dietary silicon intake in the bone status of men, a total of 400 healthy Korean adult males aged 19–25 were observed for their diet intake and calcaneus bone density using the 24-h recall method and quantitative ultrasound, respectively. Clinical markers reflecting bone metabolism such as serum total alkaline phosphatase, N-mid osteocalcin, and type 1 collagen C-terminal telopeptide concentrations were also analyzed. Silicon intake of the subjects was estimated as 37.5 ± 22.2 mg/day. Major food sources of dietary silicon in the Korean male were cereal and cereal products (25.6 % of total silicon intake), vegetables (22.7 %), beverages and liquors (21.2 %), and milk and milk products (7.0 %). Silicon intake correlated positively with age, weight, energy intake, protein intake, calcium intake, and alcohol intake. After adjusted for age, weight, energy intake, protein intake, calcium intake, alcohol intake, smoking cigarettes, and regular exercise status, daily total silicon intake had no correlation with calcaneus bone density and the bone metabolism markers, but silicon intake from vegetables had a positive correlation with serum total alkaline phosphatase activity, a bone formation maker. These findings show the possible positive relationship between dietary silicon intake from vegetables and the bone formation of young adult males. Further investigation in a larger (Korean) population and correcting for additional nutritional confounders is required to confirm these findings.     

Catabolic and anabolic periarticular bone changes in patients with rheumatoid arthritis: a computed tomography study on the role of age,disease duration and bone markers

Introduction

The aim of this study was to determine the factors, including markers of bone resorption and bone formation, which determine catabolic and anabolic periarticular bone changes in patients with rheumatoid arthritis (RA).

Methods

Forty RA patients received high-resolution peripheral quantitative computed tomography (HR-pQCT) analysis of the metacarpophalangeal joints II and III of the dominantly affected hand at two sequential time points (baseline, one year follow-up). Erosion counts and scores as well as osteophyte counts and scores were recorded. Simultaneously, serum markers of bone resorption (C-terminal telopeptide of type I collagen (CTX I), tartrate-resistant acid phosphatase 5b (TRAP5b)), bone formation (bone alkaline phosphatase (BAP), osteocalcin (OC)) and calcium homeostasis (parathyroid hormone (PTH), 25-hydroxyvitamin D3 (Vit D)) were assessed. Bone biomarkers were correlated to imaging data by partial correlation adjusting for various demographic and disease-specific parameters. Additionally, imaging data were analyzed by mixed linear model regression.

Results

Partial correlation analysis showed that TRAP5b levels correlate significantly with bone erosions, whereas BAP levels correlate with osteophytes at both time points. In the mixed linear model with erosions as the dependent variable, disease duration (P <0.001) was the key determinant for these catabolic bone changes. In contrast, BAP (P = 0.001) as well as age (P = 0.018), but not disease duration (P = 0.762), were the main determinants for the anabolic changes (osteophytes) of the periarticular bone in patients with RA.

Conclusions

This study shows that structural bone changes assessed with HR-pQCT are accompanied by alterations in systemic markers of bone resorption and bone formation. Besides, it can be shown that bone erosions in RA patients depend on disease duration, whereas osteophytes are associated with age as well as serum level of BAP. Therefore, these data not only suggest that different variables are involved in formation of bone erosions and osteophytes in RA patients, but also that periarticular bone changes correlate with alterations in systemic markers of bone metabolism, pointing out BAP as an important parameter.     

Combined Oral Administration of Bovine Collagen Peptides with Calcium Citrate Inhibits Bone Loss in Ovariectomized Rats

Purpose

Collagen peptides (CPs) and calcium citrate are commonly used as bone health supplements for treating osteoporosis. However, it remains unknown whether the combination of oral bovine CPs with calcium citrate is more effective than administration of either agent alone.

Methods

Forty 12-week-old Sprague-Dawley rats were randomly divided into five groups (n = 8) for once-daily intragastric administration of different treatments for 3 months at 3 months after ovariectomy (OVX) as follows: sham + vehicle; OVX + vehicle; OVX + 750 mg/kg CP; OVX + CP-calcium citrate (75 mg/kg); OVX + calcium citrate (75 mg/kg). After euthanasia, the femurs were removed and analyzed by dual energy X-ray absorptiometry and micro-computed tomography, and serum samples were analyzed for bone metabolic markers.

Results

OVX rats supplemented with CPs or CP-calcium citrate showed osteoprotective effects, with reductions in the OVX-induced decreases in their femoral bone mineral density. Moreover, CP-calcium citrate prevented trabecular bone loss, improved the microarchitecture of the distal femur, and significantly inhibited bone loss with increased bone volume, connectivity density, and trabecular number compared with OVX control rats. CP or CP-calcium citrate administration significantly increased serum procollagen type I N-terminal propeptide levels and reduced serum bone-specific alkaline phosphatase, osteocalcin, and C-telopeptide of type I collagen levels.

Conclusions

Our data indicate that combined oral administration of bovine CPs with calcium citrate inhibits bone loss in OVX rats. The present findings suggest that combined oral administration of bovine CPs with calcium citrate is a promising alternative for reducing bone loss in osteopenic postmenopausal women.     

Effects of streptozotocin-induced diabetes mellitus on some bone turnover markers in the vertebrae of ovary-intact and ovariectomized adult rats.

Diabetes mellitus and estrogen deficit are known causes of osteopenia in animal models as well as in humans. In the present work, the combined effect of ovariectomy and diabetes was investigated. Diabetes was induced in ovary-intact and ovariectomized female Wistar rats with a single injection (50 mg/kg body weight, i.p.) of streptozotocin. The rats were administered insulin (I) daily or 17-beta estradiol (E2) on alternate days for a period of 35 days and sacrificed. Serum calcium (Ca2+), phosphorus (P), alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TRAP), vertebral ALP, collagen, and glycosaminoglycans were estimated. The levels of serum Ca2+ and P increased in diabetic rats, but decreased after I or E2 treatments. Serum ALP and TRAP activity increased in the ovary-intact and ovariectomized diabetic rats. Vertebral ALP activity increased in ovariectomized diabetic rats, but decreased in diabetic rats, which were treated with I or E2. In the vertebrae, TRAP activity was elevated as a result of diabetes, but this was prevented by insulin or estradiol. Diabetes induced a decrease in total collagen in the vertebrae, while I or E2 treatment induced an increase. The levels of chondroitin sulphate and heparan sulphate decreased significantly in the vertebrae of both ovary-intact and ovariectomized diabetic rats, while hyaluronic acid increased. In conclusion, diabetes and ovariectomy each seem to affect the process of matrix formation and mineralization in the bone, and this is aggravated by the combination of diabetes and ovariectomy. The effects of I and E2 were similar, and both hormones reversed the changes brought about by diabetes.     

Dexamethasone induction of osteoblast mRNAs in rat marrow stromal cell cultures

We have examined the ability of dexamethasone, retinoic acid, and vitamin D3 to induce osteogenic differentiation in rat marrow stromal cell cultures by measuring the expression of mRNAs associated with the differentiated osteoblast phenotype as well as analyzing collagen secretion and alkaline phosphatase activity. Marrow cells were cultured for 8 days in primary culture and 8 days in secondary culture, with and without 10 nM dexamethasone or 1 microM retinoic acid. Under all conditions, cultures produced high levels of osteonectin mRNA. Cells grown with dexamethasone in both primary and secondary culture contained elevated alkaline phosphatase mRNA and significant amounts of type I collagen and osteopontin mRNA. Addition of 1,25-dihydroxyvitamin D3 to these dexamethasone-treated cultures induced expression of osteocalcin mRNA and increased osteopontin mRNA. The levels of alkaline phosphatase, osteopontin, and osteocalcin mRNAs in Dex/Dex/VitD3 cultures were comparable to those of 1,25-dihydroxyvitamin D3-treated ROS 17/2.8 osteosarcoma cells. Omitting dexamethasone from either primary or secondary culture resulted in significantly less alkaline phosphatase mRNA, little osteopontin mRNA, and no osteocalcin mRNA. Retinoic acid increased alkaline phosphatase activity to a greater extent than did dexamethasone but did not have a parallel effect on the expression of alkaline phosphatase mRNA and induced neither osteopontin or osteocalcin mRNAs. In all conditions, marrow stromal cells synthesized and secreted a mixture of type I and III collagens. However, dexamethasone-treated cells also synthesized an additional collagen type, provisionally identified as type V. The synthesis and secretion of collagens type I and III was decreased by both dexamethasone and retinoic acid. Neither dexamethasone nor retinoic acid induced mRNAs associated with the chondrogenic phenotype. We conclude that dexamethasone, but not retinoic acid, promotes the expression of markers of the osteoblast phenotype in cultures of rat marrow stromal fibroblasts.     

Separate and overlapping specificities in rheumatoid arthritis antibodies binding to citrulline- and homocitrulline-containing peptides related to type I and II collagen telopeptides

IntroductionOur objective was to find out if there are antibodies binding to homocitrulline-containing type I and II collagen carboxyterminal telopeptides in sera of patients with rheumatoid arthritis (RA), and if these antibodies cross-react with citrulline and homocitrulline in the same peptide sequence.MethodsA total of 72 RA and 72 control sera were analyzed for binding using enzyme-linked immunosorbent assay to citrulline- or homocitrulline-containing type I and II collagen carboxyterminal telopeptides, as well as to cyclic citrullinated peptide (CCP) and to mutated citrullinated vimentin (MCV). Specificities of the antibodies were tested using inhibition-ELISA.ResultsOf the RA sera, 39 (54%) and 41 (57%) were positive for binding to CCP and MCV, respectively. Further, 34 (47%) and 30 (42%) of the patients had specific antibodies binding to and being inhibited by citrulline-containing type I collagen telopeptides and by citrulline-containing type II collagen carboxyterminal telopeptides, respectively. The corresponding figures regarding homocitrulline-containing type I and homocitrulline-containing type II collagen telopeptides were 16 (22%) and 14 (19%). Most of the patients, who were seropositive for citrullinated peptides, showed binding in multiple assays. A total of 10 (14%) RA patients were positive for all the tested peptide pairs, while 28 (39%) of them had antibodies that contained overlapping specifities between citrulline and homocitrulline in the same peptide sequence.ConclusionsAntibodies to both citrulline and homocitrulline containing type I and II collagen telopeptides can be found in sera of RA patients. These antibodies are not constant from one RA patient to another, but contain separate or overlapping specificities within the same peptide sequence varying between individuals. Our results suggest some relationship between citrulline and homocitrulline-recognizing antibodies, since homocitrulline antibodies exist mainly in individuals seropositive to anti-CCP and anti-MCV.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-014-0515-z) contains supplementary material, which is available to authorized users.     

Extracellular matrix protein mediated regulation of the osteoblast differentiation of bone marrow derived human mesenchymal stem cells

The biomimetic approach of tissue engineering exploits the favorable properties of the extracellular matrix (ECM), to achieve better scaffold performance and tissue regeneration. ECM proteins regulate cell adhesion and differentiation through integrin mediated signal transduction. In the present study, we have examined the role of ECM proteins such as collagen type I, fibronectin, laminin and vitronectin in regulating the proliferation and osteogenic differentiation of bone marrow derived human mesenchymal stem cells (hMSCs). hMSCs were grown on selected ECM protein treated tissue culture plates. The growth kinetics was assessed by calculating the doubling time of the cells on different ECM treated plates. The cells were directed to osteoblast lineage by growing them in osteogenic induction media for 21 day. Differentiation was evaluated at different time points by osteoblast differentiation associated gene expression, alkaline phosphatase (ALP) activity, histochemical staining for mineralized matrix and calcium quantification. The doubling time of hMSCs cultured on collagen type I was significantly low, which was followed by laminin and fibronectin treated plates. However, doubling time of hMSCs cultured on vitronectin treated plate was not significantly different than that of the untreated control. High ALP gene (ALPL) expression and associated enhancement of mineralization were observed on collagen type I, fibronectin and vitronectin treated plates. Collagen type I showed early onset of mineralization with high ALP activity and up-regulation of osteopontin, ALPL, bone sialoprotein and osteocalcin genes. Vitronectin also up-regulated these genes and showed the highest amount of calcium in the secreted mineral matrix. Therefore, we conclude that, ECM proteins indeed modified the growth patterns and induced the osteoblast differentiation of hMSCs. Our findings have significant implication for bone tissue engineering applications.