Osteopontin is associated with increased arterial stiffness in rheumatoid arthritis

Relationships between Osteopontin, Osteoprotegerin, and Other Extracellular Matrix Proteins in Calcifying Arteries

Osteopontin (OPN) and osteoprotegerin (OPG) are glycoproteins that participate in the regulation of tissue biomineralization. The aim of the project is to verify the hypothesis that the content of OPN and OPG in the aorta walls increases with the development of atherosclerosis and that these proteins are quantitatively related to the main proteins in the extracellular arteries matrix. Quantitative and qualitative analyses of the OPN and OPG content in 101 aorta sections have been conducted. Additionally, an enzyme-linked immunosorbent assay (ELISA) test has been performed to determine the collagen types I-IV and elastin content in the tissues. Correlations between the biochemical data and patients' age/sex, atherosclerosis stages, and calcification occurrences in the tissue have been established. We are the first to report correlations between OPN or OPG and various types of collagen and elastin content (OPG/type I collagen correlation: r = 0.37, p = 0.004; OPG/type II collagen: r = 0.34, p = 0.007; OPG/type III collagen: r = 0.39, p = 0.002, OPG/type IV collagen: r = 0.27, p = 0.03; OPG/elastin: r = 0.42, p = 0.001; OPN/collagen type I: r = 0.34, p = 0.007; OPN/collagen type II: r = 0.52, p = 0.000; OPN/elastin: r = 0.61, p = 0.001). OPN overexpression accompanies calcium deposit (CA) formation with the protein localized in the calcium deposit, whereas OPG is located outside the CA. Although OPN and OPG seem to play a similar function (inhibiting calcification), these glycoproteins have different tissue localizations and independent expression regulation. The independent expression regulation presumably depends on the factors responsible for stimulating the synthesis of collagens and elastin.

Osteopontin, osteoprotegerin and musculoskeletal ultrasound findings in first-degree relatives of rheumatoid arthritis: potential markers of preclinical disease

BACKGROUND

First-degree relatives (FDRs) of rheumatoid arthritis (RA) patients are known to have increased risk of developing the disease. The detection of altered bone metabolism in FDRs could be a predictor of the disease. Musculoskeletal ultrasound (MSUS) is known for its ability to detect subclinical joint inflammation in RA, but changes in FDRs are not yet described. We aimed to study serum Osteopontin (OPN) and Osteoprotegerin (OPG) levels in FDRs of RA patients as markers of altered bone metabolism in relation to clinical, laboratory and musculoskeletal ultrasound (MSUS) findings.

METHODS

Fifty-five individuals were included, 20 had definite RA, 25 were first degree relatives (FDRs) of RA patients, and 10 healthy controls. Clinical evaluation for joint swelling/tenderness was performed for all. ESR, CRP, rheumatoid factor (RF), anti-citrullinated antibodies (ACPA), OPN, OPG, and Musculoskeletal ultrasound (MSUS) by the US7 score were evaluated.

RESULTS

Osteoprotegerin was significantly higher in RA (143.89 pg/ml ± 365.47) than in FDRs (22.23 pg/ml ± 65.73; p = 0.009) and controls (6.20 pg/ml ± 12.43; p = 0.003). OPN was also higher in RA (3.66 ng/ml ± 4.20) than in FDRs (1.97 ng/ml ± 1.04) and controls (2.81 ng/ml ± 1.31), though not significant (p = 0.102). Eight of 25 FDRs (32%) had arthralgia without clinical arthritis and 17/25 (68%) were asymptomatic. FDRs with arthralgia had significantly higher ESR and CRP levels than asymptomatic FDRs (9.82 mm/h ± 4.13; p = 0.003, and 3.93 mg/l ± 3.58; p = 0.003). Osteoprotegerin was higher in FDRs than in controls, and also in those with arthralgia (51.55 pg/ml ± 114.68) than in those without (8.44 pg/ml ± 9.67), though without significant difference. OPN was higher in FDRs with arthralgia (2.09 ng/ml ± 1.19) than in asymptomatic (1.70 ng/ml ± 0.55), also without significant difference. Pathologic findings by US7 were detected in 10/25 (40%) FDRs, of which three (12%) had arthralgia and seven (28%) were asymptomatic.

CONCLUSIONS

The raised OPG and lower OPN in FDRs than in controls reflect an altered bone metabolism which could precede clinical disease phase. OPN and OPG could serve as markers of altered preclinical bone metabolism in FDRs of RA. US7 score might be a useful screening tool to identify 'at-risk' individuals.

Osteopontin: A Bone-Derived Protein Involved in Rheumatoid Arthritis and Osteoarthritis Immunopathology

Osteopontin (OPN) is a bone-derived phosphoglycoprotein related to physiological and pathological mechanisms that nowadays has gained relevance due to its role in the immune system response to chronic degenerative diseases, including rheumatoid arthritis (RA) and osteoarthritis (OA). OPN is an extracellular matrix (ECM) glycoprotein that plays a critical role in bone remodeling. Therefore, it is an effector molecule that promotes joint and cartilage destruction observed in clinical studies, in vitro assays, and animal models of RA and OA. Since OPN undergoes multiple modifications, including posttranslational changes, proteolytic cleavage, and binding to a wide range of receptors, the mechanisms by which it produces its effects, in some cases, remain unclear. Although there is strong evidence that OPN contributes significantly to the immunopathology of RA and OA when considering it as a common denominator molecule, some experimental trial results argue for its protective role in rheumatic diseases. Elucidating in detail OPN involvement in bone and cartilage degeneration is of interest to the field of rheumatology. This review aims to provide evidence of the OPN’s multifaceted role in promoting joint and cartilage destruction and propose it as a common denominator of AR and OA immunopathology.

Associations of childhood adiposity with adult intima-media thickness and inflammation: a 20-year longitudinal population-based cohort

BACKGROUND

The associations between childhood adiposity and adult increased carotid intima-media thickness (cIMT) have been well established, which might be corroborated by the association between adiposity in children and inflammation in adults. However, longitudinal data regarding biological pathways associated with childhood adiposity are lacking.

METHODS

The current study included participants from the STANISLAS cohort who had adiposity measurements at age 5-18 years [ N  = 519, mean (SD) age, 13.0 (2.9) years; 46.4% male], and who were measured with cIMT, vascular-related and metabolic-related proteins at a median follow-up of 19 ± 2 years. BMI, waist-to-height ratio and waist circumference were converted to age-specific and sex-specific z -scores.

RESULTS

A minority of children were overweight/obese (16.2% overweight-BMI z -score >1; 1.3% obesity- z -score >2). Higher BMI, waist-height ratio and waist circumference in children were significantly associated with greater adult cIMT in univariable analysis, although not after adjusting for C-reactive protein. These associations were more pronounced in those with consistently high adiposity status from childhood to middle adulthood. Participants with higher adiposity during childhood (BMI or waist-height ratio) had higher levels of insulin-like growth factor-binding protein-1, protein-2, matrix metalloproteinase-3, osteopontin, hemoglobin and C-reactive protein in adulthood. Network analysis showed that IL-6, insulin-like growth factor-1 and fibronectin were the key proteins associated with childhood adiposity.

CONCLUSION

In a population-based cohort followed for 20 years, higher BMI or waist-to-height ratio in childhood was significantly associated with greater cIMT and enhanced levels of proteins reflective of inflammation, supporting the importance of inflammation as progressive atherosclerosis in childhood adiposity.

Inflammaging as a link between autoimmunity and cardiovascular disease: the case of rheumatoid arthritis

Currently, traditional and non-traditional risk factors for cardiovascular disease have been established. The first group includes age, which constitutes one of the most important factors in the development of chronic diseases. The second group includes inflammation, the pathophysiology of which contributes to an accelerated process of vascular remodelling and atherogenesis in autoimmune diseases. Indeed, the term inflammaging has been used to refer to the inflammatory origin of ageing, explicitly due to the chronic inflammatory process associated with age (in healthy individuals). Taking this into account, it can be inferred that people with autoimmune diseases are likely to have an early acceleration of vascular ageing (vascular stiffness) as evidenced in the alteration of non-invasive cardiovascular tests such as pulse wave velocity. Thus, an association is created between autoimmunity and high morbidity and mortality rates caused by cardiovascular disease in this population group. The beneficial impact of the treatments for rheumatoid arthritis at the cardiovascular level has been reported, opening new opportunities for pharmacotherapy.

Serum osteopontin negatively impacts on intima-media thickness in patients with systemic lupus erythematosus

BACKGROUND

Ultrasound evaluation of carotid intima-media thickness (cIMT) has been extensively used for potentially improving cardiovascular (CV) risk stratification in several patients' categories. Subjects with systemic lupus erythematosus (SLE) have been investigated by both imaging and molecular biomarker approaches with contrasting results. Here, we focused on the role of osteopontin (OPN) as biomarker of subclinical atherosclerosis associated with SLE.

MATERIALS AND METHODS

Eighty females (age 18-65 years) affected by SLE and eighty age-matched healthy female controls without a clinical history of CV disease underwent ultrasound evaluation of cIMT and blood sample assay of high-sensitivity C-reactive protein (hs-CRP) and OPN.

RESULTS

Healthy controls and SLE patients significantly differed for CV risk factors (ie, waist circumference, hypertension and dyslipidaemia) and the inflammatory status. Noteworthy, an opposite association between cIMT and OPN was observed in the two study groups. Whereas OPN was positively associated with mean cIMT (r = 0.364; P = 0.001) in SLE patients, a negative correlation was found in healthy controls. Furthermore, in SLE patients increased circulating levels of OPN were associated with the use of hydroxychloroquine and the positivity for the anti-dsDNA autoantibodies. At linear regression analysis, only OPN remained independently associated with cIMT also after adjustment for age, smoking pack-year, Heart SCORE, disease length and steroid therapy length.

CONCLUSIONS

These results indicate that serum OPN levels were strongly associated with subclinical atherosclerosis in patients with LES and it might be a useful CV biomarker that requires additional validation in larger trials.

Association between bone metabolism regulators and arterial stiffness in type 2 diabetes patients

BACKGROUND AND AIM

Osteopontin (OPN), osteonectin (ON) and osteocalcin (OC) play an important role in the development of vascular calcifications, but it is unclear whether these bone metabolism regulators contribute to the development of arterial stiffness in type 2 diabetes patients. We therefore aim to determine the relationship between plasma concentrations of OPN, ON, OC and arterial stiffness in type 2 diabetes patients.

METHODS

Cross-sectional study of 1003 type 2 diabetes patients included in the Second Manifestations of ARTerial disease (SMART)-cohort. Generalized linear models were used to evaluate the relation between plasma levels of OPN, ON and OC and arterial stiffness as measured by pulse pressure (PP), ankle-brachial index (ABI) (≥0.9), carotid artery distension and an arterial stiffness summary score. Analyses were adjusted for age, sex, kidney function, diabetes duration and diastolic blood pressure. Higher OPN plasma levels were significantly related to a lower ABI (β-0.013; 95%CI -0.024 to -0.002) and a higher arterial stiffness summary score (OR1.24; 95%CI 1.03-1.49). OPN levels were not related to PP (β 0.59; 95%CI -0.63-1.81) or absolute carotid artery distention (β -7.03; 95%CI -20.00-5.93). ON and OC plasma levels were not related to any of the arterial stiffness measures.

CONCLUSION

Only elevated plasma levels of OPN are associated with increased arterial stiffness in patients with type 2 diabetes as measured by the ankle-brachial index and arterial stiffness summary score. These findings indicate that OPN may be involved in the pathophysiology of arterial stiffness and call for further clinical investigation.

Circulating Levels of Osteoprotegerin, Osteocalcin and Osteopontin in Patients with Rheumatoid Arthritis: A Systematic Review and Meta-Analysis

OBJECTIVE

Currently published data regarding the potential role of osteoprotegerin (OPG), osteocalcin (OCN) and osteopontin (OPN) for the discrimination between rheumatoid arthritis (RA) and osteoarthritis (OA) are contradictory. To derive a more precise evaluation, a meta-analysis was performed.

METHODS

Published literatures comparing plasma/serum OPG, OCN and OPN levels between RA group and OA controls were searched in PubMed, Embase and the Cochrane Library. The Newcastle-Ottawa Scale was used to assess the study quality. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by random-effect model analysis. Heterogeneity test was performed by the Q statistic and quantified using I².

RESULTS

Nine studies including 438 RA patients and 255 OA patients were finally incorporated in the meta-analysis after examining title, type, abstracts and full text. The results showed that RA patients had higher plasma/serum OPN (pooled SMD = -2.57, 95% CI = -4.72 to -0.41) levels when compared to OA patients. No significant difference in plasma/serum OPG (pooled SMD = -0.29, 95% CI = -1.07‒0.49) and OCN (pooled SMD = -0.09, 95% CI = -0.48‒0.31) levels were found between RA patients and OA patients. Subgroup analysis indicated that plasma/serum OPG levels had no significant differences between RA patients and OA patients in Europe and Asian.

CONCLUSIONS

Overall, there is no significant difference in circulating OPG and OCN levels between RA patients and OA patients. However, plasma/serum OPN level is significantly higher in RA patients compared with OA patients.

Effects on bone metabolism markers and arterial stiffness by switching to rivaroxaban from warfarin in patients with atrial fibrillation

In recent years, direct oral anticoagulants (DOACs) of dabigatran, rivaroxaban, apixaban, edoxaban, which are all alternatives to warfarin, have been released. The use of DOACs is becoming more widespread in the clinical management of thrombotic stroke risk in patients with atrial fibrillation (AF). In large-scale clinical trials of each drug, DOACs were reported to inhibit intracranial hemorrhage, stroke, and death compared to warfarin. Warfarin is an endogenous vitamin K antagonist; therefore, patients who are taking warfarin must be prohibited from taking vitamin K. Vitamin K is an essential cofactor required for the ɤ-carboxylation of vitamin K-dependent proteins including coagulation factors, osteocalcin (OC), matrix Gla protein (MGP), and the growth arrest-specific 6 (GAS6). OC is a key factor for bone matrix formation. MGP is a local inhibitor of soft tissue calcification in the vessel wall. GAS6 prevents the apoptosis of vascular smooth muscle cells. Therefore, decrease of blood vitamin K levels may cause osteoporosis, vascular calcification, and the inhibition of vessels angiogenesis. This study aimed to evaluate the effects of changing from warfarin to rivaroxaban on bone mineral metabolism, vascular calcification, and vascular endothelial dysfunction. We studied 21 consecutive patients with persistent or chronic AF, who were treated with warfarin at least for 12 months. Warfarin administration was changed to rivaroxaban (10 or 15 mg/day) in all patients. Osteopontin (OPN), bone alkaline phosphatase (BAP), and under-carboxylated osteocalcin (ucOC) were measured. Pulse wave velocity (PWV) and augmentation index (AI) were also measured as atherosclerosis assessments. All measurements were done before and six months after the rivaroxaban treatment. There was a significant increase in serum level of BAP compared to baseline (12.5 ± 4.6 to 13.4 ± 4.1 U/L, P < 0.01). In contrast, there was a significant decrease in the serum level of ucOC (9.5 ± 5.0 to 2.7 ± 1.3 ng/ml, P < 0.01). Also, in the ucOC levels, there was a significant negative correlation between baseline values and baseline to 6-months changes in high ucOC group (r = -0.97, P < 0.01). The atherosclerosis- and osteoporosis-related biomarker, serum level of OPN were significantly decreased compared to baseline (268.3 ± 46.8 to 253.4 ± 47.1 ng/ml, P < 0.01). AI and PWV were significantly decreased after 6 months of treatment with rivaroxaban (33.9 ± 18.4 to 24.7 ± 18.4%, P = 0.04; 1638.8 ± 223.0 to 1613.0 ± 250.1 m/s, P = 0.03, respectively). Switching to rivaroxaban from warfarin in patients with atrial fibrillation was associated with an increase of bone formation markers and a decrease of bone resorption markers, and also improvements of PWV and AI.

Increased circulating osteopontin levels in adult patients with type 1 diabetes mellitus and association with dysmetabolic profile

OBJECTIVE

Osteopontin (OPN) is a sialoprotein implicated in different immunity and metabolic pathways. Capable of activating dendritic cells and inducing Th1-Th17-mediated tissue damage, OPN plays a significant role in the development/progression of several autoimmune diseases; interestingly, it was also shown that OPN participates in the acute pancreatic islets response to experimentally induced diabetes in non-obese diabetic (NOD) mice. Furthermore, OPN promotes adipose tissue dysfunction, systemic inflammation and insulin resistance. Our aims of this study were to evaluate circulating OPN levels in adult patients with type 1 diabetes mellitus (T1DM) compared to non-diabetic control participants and to unravel clinical and biochemical correlates of OPN concentration.

DESIGN

Case-control study.

METHODS

We enrolled 54 consecutive T1DM patients referred to our diabetes outpatient clinic at Sapienza University of Rome and 52 healthy sex and age-comparable controls. The study population underwent clinical evaluation, blood sampling for biochemistry and complete screening for diabetes complications. Serum OPN levels were measured by MILLIPLEX Multiplex Assays Luminex.

RESULTS

T1DM patients had significantly higher serum OPN levels than controls (17.2±12.9 vs 10.5±11.6 mg/ml, P=0.009). OPN levels correlated with T1DM, higher blood pressure, BMI, creatinine, γ-GT, ALP and lower HDL; the association between high OPN levels and T1DM was independent from all confounders. No correlation was shown between OPN and HbA1c, C-peptide, insulin requirement, co-medications and diabetes duration.

CONCLUSIONS

This study demonstrates for the first time in a case-control study that adults with T1DM have increased serum OPN levels, and that higher OPN concentrations are associated with an unfavorable metabolic profile in these patients.

Vascular calcification: from pathophysiology to biomarkers

The link between vascular calcification (VC) and increased mortality is now well established. Over time, as clinical importance of this phenomenon has begun to be fully considered, scientists have highlighted more and more physiopathological mechanisms and signaling pathways that underlie VC. Several conditions such as diabetes, dyslipidemia and renal diseases are undoubtedly identified as predisposing factors. But even if the process is better understood, many questions still remain unanswered. This review briefly develops the various theories that attempt to explain mineralization genesis. Nonetheless, the main purpose of the article is to provide a profile of the various existing biomarkers of VC. Indeed, in the past years, a lot of inhibitors and promoters, which form a dense and interconnected network, were identified. Given importance to assess and control mineralization process, a focusing on accumulated knowledge of each marker seemed to be necessary. Therefore, we tried to define their respective role in the physiopathology and how they can contribute to calcification risk assessment. Among these, Klotho/fibroblast growth factor-23, fetuin-A, Matrix Gla protein, Bone morphogenetic protein-2, osteoprotegerin, osteopontin, osteonectin, osteocalcin, pyrophosphate and sclerostin are specifically discussed.

Cardiovascular involvement in autoimmune diseases

Autoimmune diseases (AD) represent a broad spectrum of chronic conditions that may afflict specific target organs or multiple systems with a significant burden on quality of life. These conditions have common mechanisms including genetic and epigenetics factors, gender disparity, environmental triggers, pathophysiological abnormalities, and certain subphenotypes. Atherosclerosis (AT) was once considered to be a degenerative disease that was an inevitable consequence of aging. However, research in the last three decades has shown that AT is not degenerative or inevitable. It is an autoimmune-inflammatory disease associated with infectious and inflammatory factors characterized by lipoprotein metabolism alteration that leads to immune system activation with the consequent proliferation of smooth muscle cells, narrowing arteries, and atheroma formation. Both humoral and cellular immune mechanisms have been proposed to participate in the onset and progression of AT. Several risk factors, known as classic risk factors, have been described. Interestingly, the excessive cardiovascular events observed in patients with ADs are not fully explained by these factors. Several novel risk factors contribute to the development of premature vascular damage. In this review, we discuss our current understanding of how traditional and nontraditional risk factors contribute to pathogenesis of CVD in AD.

Serum osteopontin level correlates with carotid-femoral pulse wave velocity in geriatric persons

Osteopontin (OPN) is involved in the regulation of vascular calcification processes. The aim of this study was to evaluate the relationship between fasting serum OPN concentration and carotid-femoral pulse wave velocity (cfPWV) in geriatric persons. Fasting blood samples were obtained from 93 geriatric persons. cfPWV were performed by SphygmoCor system. Serum OPN levels were measured using a commercially available enzyme-linked immunosorbent assay. Geriatric adults who had diabetes (P = 0.007) or dyslipidemia (P = 0.029) had higher cfPWV levels than those without diabetes or dyslipidemia. The univariable linear regression analysis showed that age (P = 0.002), waist circumference (P = 0.048), body mass index (P = 0.004), systolic blood pressure (P = 0.001), diastolic blood pressure (P = 0.036), pulse pressure (P = 0.017), creatinine (P = 0.002), and log-OPN level (P = 0.001) were positively correlated with cfPWV levels, while the high-density lipoprotein cholesterol (HDL-cholesterol) level (P = 0.007) and glomerular filtration rate (P = 0.001) were negatively correlated with cfPWV levels among the geriatric adults. Multivariable forward stepwise linear regression analysis of the significant variables also showed that log-OPN (β = 0.233, R (2) = 0.123, regression coefficient: 1.868, P = 0.011) was still an independent predictor of cfPWV levels in geriatric persons.

Bone metabolism regulators and arterial stiffness in postmenopausal women

BACKGROUND

Osteoprotegerin (OPG), osteopontin (OPN) and matrix Gla protein (MGP) are markers of bone metabolism but they are also involved in vascular calcification. However, their precise role is not completely understood. Arterial stiffness is considered an independent predictor of cardiovascular events and it may be one of the causes of the increased cardiovascular risk associated with postmenopausal status. Medial and intimal calcification may increase arterial stiffness. The aim of our study was to assess the relationship of OPG, OPN and MGP with aortic pulse wave velocity (aPWV) as a marker of arterial stiffness in postmenopausal women.

MATERIALS AND METHODS

Circulating OPG, OPN and serum total MGP were measured in 144 postmenopausal women using the enzyme-linked immunosorbent assay method. Aortic PWV was determined by an oscillometric method.

RESULTS

Osteoprotegerin correlated with age (p<0.001, r=0.27), aPWV (p<0.001, r=0.32) and hypersensitive C reactive protein (hsCRP) (p<0.001, r=0.37), OPN correlated directly with hsCRP (p<0.001, r=0.39) and inversely with high density lipoprotein cholesterol (p=0.02, r=-0.02). No significant association was found between total MGP and clinical, biochemical and vascular parameters. The correlation between OPG and aPWV persisted even after the adjustment for various potential confounders (p=0.02, r=0.19). In multiple regression analysis in the whole study population the most important predictors of aPWV were OPG (β=0.230, p=0.006), hsCRP (β=0.212, p=0.01) and systolic blood pressure (β=0.163, p=0.04). After exclusion of patients treated with statins the independent predictors were hsCRP (β=0.275, p=0.005) and OPG (β=0.199, p=0.04).

CONCLUSION

Circulating OPG, but not OPN and total MGP, is associated with aPWV and may be a marker of the increased arterial stiffness and cardiovascular risk in postmenopausal women.

Cardiovascular risk in rheumatoid arthritis: pathogenesis, diagnosis, and management

Rheumatoid arthritis is characterized by early and accelerated atherosclerosis leading to increased cardiovascular morbidity and mortality. Beyond traditional cardiovascular risk factors, several pathogenetic mechanisms have been proposed, including emerging inflammatory and autoimmune mechanisms. Inflammatory stimuli are now believed to cause vascular damage, which can be estimated by well-established noninvasive techniques. Carotid intima-media thickness, pulse-wave velocity and flow-mediated dilatation, markers of subclinical atherosclerosis, arterial stiffness, and endothelial function, respectively, have been recently used to detect vascular dysfunction in the wide spectrum of autoimmune diseases. The role of anti-tumor necrosis factor α and novel biologic agents remains unclear, although early control of the inflammatory process seems crucial for reducing cardiovascular risk. Considering the importance of cardiovascular risk management, further well-designed studies are warranted to clarify the potential benefits and harms of anti-inflammatory treatment.

A study of the link between bone turnover markers and bone mineral density with inflammation and body mass in postmenopausal women with active rheumatoid arthritis

In this study, the levels of bone turnover markers (BTMs) and bone mineral density (BMD) were studied in relation to body mass and several inflammatory markers, in postmenopausal patients with rheumatoid arthritis (RA). Fifty-nine postmenopausal women with active RA (lean, overweight, obese) were studied. The femoral BMD and serum levels of BTMs: osteocalcin (OC) and collagen type I cross-linked C-telopeptide fragments (CTX), and osteopontin (OPN), resistin, high sensitivity C-reactive protein, interleukin-6, tumor necrosis factor (TNF)-α in these patients were measured. It has been noticed that obese women had significantly higher total femoral BMD and total T-score compared to the lean subjects (p ≤ 0.01). The significant associations of BMD measures and CTX levels with body mass parameters (p ≤ 0.01 and p < 0.05, respectively) were found. Values of neck BMD adjusted for BMI were inversely associated with concentrations of TNF-α (p < 0.05). Osteocalcin levels inversely correlated with resistin (p ≤ 0.01) and CTX levels positively correlated with OPN (p ≤ 0.01). There were found no associations between BTMs and BMD with other inflammatory indices. Inverse correlations between OPN levels and body mass (p < 0.05), waist circumference (p < 0.05), and duration of postmenopausal period (p ≤ 0.01) were observed. Findings of the present study suggest that body mass and inflammatory markers, most of all OPN, resistin and TNF-α, play an important role in bone metabolism in postmenopausal women with active RA.

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.

Structural and biochemical characteristics of arterial stiffness in patients with atherosclerosis and in healthy subjects

Arterial stiffness is an independent predictor of vascular morbidity and mortality in patients with atherosclerosis. Angiographic score (ASc) reflects severity of atherosclerosis in patients with peripheral arterial disease (PAD). Osteopontin (OPN) and oxidized low-density lipoprotein (oxLDL) are involved in the pathogenesis of atherosclerosis. The aim of the present study was to evaluate the association between arterial stiffness, ASc, serum OPN and oxLDL in patients with symptomatic PAD, and in clinically healthy subjects. We studied 79 men with symptomatic PAD (mean age 64±7 years) and 84 healthy men (mean age 63±8 years). Calculation of the ASc was based on severity and location of atherosclerotic lesions in the arteries of the lower extremities. Aortic pulse wave velocity (aPWV) was evaluated by applanation tonometry using the Sphygmocor device. Serum OPN and oxLDL levels were determined by enzyme-linked immunosorbent assay. The aPWV (10±2.4 vs. 8.4±1.7 (m s(-1)); P<0.001), OPN (75 (62.3-85.8) vs. 54.8 (47.7-67.9) (ng ml(-1)); P<0.001) and oxLDL (67 (52.5-93.5) vs. 47.5 (37-65.5); P<0.001) were different for the patients and for the controls. In multiple regression models, aPWV was independently determined by ASc, log-OPN, log-oxLDL and estimated glomerular filtration rate in the patients (R2=0.44; P<0.001) and by log-OPN, log-oxLDL, age and heart rate in the controls (R2=0.38; P<0.001). The independent relationship of a PWV with serum levels of OPN and oxLDL in the patients with PAD and in the controls indicates that OPN and oxLDL might influence arterial stiffening in patients with atherosclerosis and in clinically healthy subjects.

Osteopontin and integrin are involved in cholesterol gallstone formation

Background

This study aimed to investigate the role of osteopontin and its receptor, integrin αv, in gallstone formation using human tissue specimens and a guinea pig lithogenic model.

Material/Methods

The nucleation role of osteopontin was determined in patients’ and normal gallbladder bile samples in vitro. Normal gallbladder was the control, and gallstone gallbladders were divided into group I (with normal epithelia) and group II (with degenerated epithelia) based on pathology change. Immunostaining, mRNA and protein expressions of osteopontin and integrin αv were analyzed. The animals were randomly divided into a lithogenic diet group and a normal diet group; the osteopontin mRNA expression in gallbladder and liver and osteopontin concentrations were determined.

Results

Osteopontin prolonged nucleation time and inhibited the pro-nucleating role induced by calcium in human bile in vitro. Immunostaining for osteopontin and integrin αv in human gallbladder tissues showed a higher reactivity in Group I than control group and Group II. The immunostaining in Group II was weaker than control group; similar results were observed for mRNA and protein expression of osteopontin and integrin αv. In the animal assay, the mRNA expression and concentration of osteopontin in gallbladder and liver gradually increased at initial stages and decreased in later stages. The concentrations of osteopontin in bile and serum of guinea pig showed similar trends.

Conclusions

Our results suggest that osteopontin is involved in cholesterol gallstone formation, and the role of osteopontin might correlate with integrin αv and calcium.

Arterial stiffness, vascular calcification and bone metabolism in chronic kidney disease

Patients with chronic kidney disease (CKD) have an extremely poor cardiovascular outcome. Arterial stiffness, a strong independent predictor of survival in CKD, is connected to arterial media calcification. A huge number of different factors contribute to the increased arterial calcification and stiffening in CKD, a process which is in parallel with impaired bone metabolism. This coincidence was demonstrated to be part of the direct inhibition of calcification in the vessels, which is a counterbalancing effect but also leads to low bone turnover. Due to the growing evidence, the definition of “CKD mineral bone disorder” was created recently, underlining the strong connection of the two phenomena. In this review, we aim to demonstrate the mechanisms leading to increased arterial stiffness and the up-to date data of the bone-vascular axis in CKD. We overview a list of the different factors, including inhibitors of bone metabolism like osteoprotegerin, fetuin-A, pyrophosphates, matrix Gla protein, osteopontin, fibroblast growth factor 23 and bone morphogenic protein, which seem to play role in the progression of vascular calcification and we evaluate their connection to impaired arterial stiffness in the mirror of recent scientific results.

The role of osteopontin (OPN/SPP1) haplotypes in the susceptibility to Crohn's disease

BACKGROUND

Osteopontin represents a multifunctional molecule playing a pivotal role in chronic inflammatory and autoimmune diseases. Its expression is increased in inflammatory bowel disease (IBD). The aim of our study was to analyze the association of osteopontin (OPN/SPP1) gene variants in a large cohort of IBD patients.

METHODOLOGY/PRINCIPAL FINDINGS

Genomic DNA from 2819 Caucasian individuals (n = 841 patients with Crohn's disease (CD), n = 473 patients with ulcerative colitis (UC), and n = 1505 healthy unrelated controls) was analyzed for nine OPN SNPs (rs2728127, rs2853744, rs11730582, rs11739060, rs28357094, rs4754 = p.Asp80Asp, rs1126616 = p.Ala236Ala, rs1126772 and rs9138). Considering the important role of osteopontin in Th17-mediated diseases, we performed analysis for epistasis with IBD-associated IL23R variants and analyzed serum levels of the Th17 cytokine IL-22. For four OPN SNPs (rs4754, rs1126616, rs1126772 and rs9138), we observed significantly different distributions between male and female CD patients. rs4754 was protective in male CD patients (p = 0.0004, OR = 0.69). None of the other investigated OPN SNPs was associated with CD or UC susceptibility. However, several OPN haplotypes showed significant associations with CD susceptibility. The strongest association was found for a haplotype consisting of the 8 OPN SNPs rs2728127-rs2853744-rs11730582-rs11439060-rs28357094-rs112661-rs1126772-rs9138 (omnibus p-value = 2.07×10⁻⁸). Overall, the mean IL-22 secretion in the combined group of OPN minor allele carriers with CD was significantly lower than that of CD patients with OPN wildtype alleles (p = 3.66×10⁻⁵). There was evidence for weak epistasis between the OPN SNP rs28357094 with the IL23R SNP rs10489629 (p = 4.18×10⁻²) and between OPN SNP rs1126616 and IL23R SNP rs2201841 (p = 4.18×10⁻²) but none of these associations remained significant after Bonferroni correction.

CONCLUSIONS/SIGNIFICANCE

Our study identified OPN haplotypes as modifiers of CD susceptibility, while the combined effects of certain OPN variants may modulate IL-22 secretion.

Increased levels of bone remodeling biomarkers (osteoprotegerin and osteopontin) in hypertensive individuals

OBJECTIVES

Osteoprotegerin (OPG) and osteopontin (OPN) are bone metabolism biomarkers which are involved in the regulation of vascular calcification processes and prediction of future adverse cardiac events.

DESIGN AND METHODS

OPG, OPN levels and classic risk factors were determined in 130 asymptomatic and hypertensive subjects. Receiver operator characteristic (ROC) analysis was performed and the area under the curve (AUC) was calculated.

RESULTS

The hypertensive subjects had elevated OPG, OPN, fibrinogen, CRP and fasting glucose levels in comparison to the normotensive ones. There were significant correlations between age, CRP and OPG. Multiple regression analysis showed that as well as inflammation (CRP), age and hypertension were predictors of increased OPG levels. OPN increase was correlated with CRP and glucose levels. The AUCs were similar for OPG and OPG biomarkers.

CONCLUSIONS

Plasma OPG and OPN levels were significantly associated with inflammation and arterial hypertension. They might be useful as additional biomarkers for monitoring endothelial dysfunction and prognosis of cardiovascular diseases.