N-Terminal Pro–B-type Natriuretic Peptide Is Inversely Related to Bone Mineral Density in Renal Transplant Recipients

Brain natriuretic peptide and N-terminal pro b-type natriuretic peptide in kidney transplantation: More than just cardiac markers

Although kidney transplantation (KT) is the best treatment option for most patients with end-stage kidney disease (ESKD) due to reduced mortality, morbidity and increased quality of life, long- term complications such as chronic kidney allograft dysfunction (CKAD) and increased cardiovascular disease burden are still major challenges. Thus, routine screening of KT recipients (KTRs) is very important to identify and quantify risks and guide preventative measures. However, no screening parameter has perfect sensitivity and specificity, and there is unmet need for new markers. In this review, we evaluate brain natriuretic peptide (BNP) and N-terminal pro b-type natriuretic peptide (NT-proBNP) as promising markers for risk stratification in the kidney transplant recipients (KTRs). The usefulness of these markers are already proven in heart failure, hypertension, coronary artery disease. In the context of KT, evidence is emerging. BNP and NT-proBNP has shown to be associated with kidney function, graft failure, echocardiographic parameters, major cardiovascular events and mortality but the underlying mechanisms are not known. Although BNP and NT-proBNP interact with immune system, renin angiotensin system and sympathetic system; it is not known whether these interactions are responsible for the clinical findings observed in KTRs. Future studies are needed whether these biomarkers show clinical efficacy, especially with regard to hard outcomes such as major adverse cardiovascular events and graft dysfunction and whether routine implementation of these markers are cost effective in KTRs.

Midregional Proatrial Natriuretic Peptide (MRproANP) is associated with vertebral fractures and low bone density in patients with chronic obstructive pulmonary disease (COPD)

BACKGROUND

Patients with COPD are often affected by loss of bone mineral density (BMD) and osteoporotic fractures. Natriuretic peptides (NP) are known as cardiac markers, but have also been linked to fragility-associated fractures in the elderly. As their functions include regulation of fluid and mineral balance, they also might affect bone metabolism, particularly in systemic disorders such as COPD.

RESEARCH QUESTION

We investigated the association between NP serum levels, vertebral fractures and BMD assessed by chest computed tomography (CT) in patients with COPD.

METHODS

Participants of the COSYCONET cohort with CT scans were included. Mean vertebral bone density on CT (BMD-CT) as a risk factor for osteoporosis was assessed at the level of TH12 (AI-Rad Companion), and vertebral compression fractures were visually quantified by two readers. Their relationship with N-terminal pro-B-type natriuretic peptide (NT-proBNP), Mid-regional pro-atrial natriuretic peptide (MRproANP) and Midregional pro-adrenomedullin (MRproADM) was determined using group comparisons and multivariable analyses.

RESULTS

Among 418 participants (58% male, median age 64 years, FEV1 59.6% predicted), vertebral fractures in TH12 were found in 76 patients (18.1%). Compared to patients without fractures, these had elevated serum levels (p ≤ 0.005) of MRproANP and MRproADM. Using optimal cut-off values in multiple logistic regression analyses, MRproANP levels ≥ 65 nmol/l (OR 2.34; p = 0.011) and age (p = 0.009) were the only significant predictors of fractures after adjustment for sex, BMI, smoking status, FEV1% predicted, SGRQ Activity score, daily physical activity, oral corticosteroids, the diagnosis of cardiac disease, and renal impairment. Correspondingly, MRproANP (p < 0.001), age (p = 0.055), SGRQ Activity score (p = 0.061) and active smoking (p = 0.025) were associated with TH12 vertebral density.

INTERPRETATION

MRproANP was a marker for osteoporotic vertebral fractures in our COPD patients from the COSYCONET cohort. Its association with reduced vertebral BMD on CT and its known modulating effects on fluid and ion balance are suggestive of direct effects on bone mineralization.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01245933, Date of registration: 18 November 2010.

The relationship between serum pro-B type natriuretic peptide level and bone mineral density in peritoneal dialysis patients

We aimed to evaluate the relationship between serum N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) and lumbar bone mineral density (BMD) in peritoneal dialysis (PD) patients. Fasting blood samples were obtained from 46 PD patients. BMD was measured by dual-energy X-ray absorptiometry of the lumbar vertebrae (L1-L4). Circulating serum NT-pro-BNP levels were measured using commercial kits compatible with the Roche Cobas e 601 immunoassay device. Forty-six patients were included in our study. Increased age, low body mass index (BMI), and high-serum NT-pro-BNP are significantly associated with decreased BMD. The results show a statistically positive correlation between lumbar T-score values and BMI (r = 0.456; P = .001), while lumbar T-score values and PTH (rho = -0.336; P = .022) and log-NT-pro-BNP. There is a statistically negative correlation between BNP (rho = -0.355; P = .015). The lumbar T-score value decreases by 0.800 units when log-NT-pro-BNP increases by 1 unit and increases by 0.323 units when BMI increases by 1 unit. The established model is statistically significant (F = 6.190; P < .001). Our study in PD patients showed that serum NT-pro-BNP level was negatively correlated and BMI was positively correlated with lumbar BMD.

Association of circulating B-type natriuretic peptide with osteoporosis in a Chinese type 2 diabetic population

Background

Altered circulating levels and genetic variation of B-type natriuretic peptide (BNP), has been associated with lower bone mineral density (BMD) values and incidence of osteoporosis in peritoneal dialysis patients, renal transplant recipients, and postmenopausal women. The potential relationship of circulating BNP with osteoporosis in patients with type 2 diabetes mellitus (T2DM), however, has not yet been studied.

Methods

Circulating BNP levels were measured in 314 patients with T2DM, and participants were divided into normal BMD group (n = 73), osteopenia group (n = 120), and osteoporosis group (n = 121). The association of circulating BNP with diabetic osteoporosis and other parameters was analyzed.

Results

Circulating BNP was significantly higher in diabetic osteoporosis subjects than normal and osteopenia groups (P < 0.01 or P < 0.05). Circulating BNP levels correlated significantly and positively with neutrophil to lymphocyte ratio, systolic blood pressure, urinary albumin-to-creatinine ratio, and prevalence of hypertension, peripheral arterial disease, diabetic retinopathy, peripheral neuropathy, and nephropathy, and negatively with triglyceride, fasting blood glucose, lymphocyte count, hemoglobin, estimated glomerular filtration rate, bilirubin, osteoporosis self-assessment tool for Asians, BMD at different skeletal sites and corresponding T scores (P < 0.01 or P < 0.05). After multivariate adjustment, circulating BNP remained independently significantly associated with the presence of osteoporosis (odds ratio, 2.710; 95% confidence interval, 1.690–4.344; P < 0.01). BMD at the femoral neck and total hip and corresponding T scores were progressively decreased, whereas the prevalence of osteoporosis was progressively increased with increasing BNP quartiles (P for trend< 0.01). Moreover, receiver-operating characteristic analysis revealed that the optimal cutoff point of circulating BNP to indicate diabetic osteoporosis was 16.35 pg/ml.

Conclusions

Circulating BNP level may be associated with the development of osteoporosis, and may be a potential biomarker for diabetic osteoporosis.

Serum Irisin Level Is Positively Associated with Bone Mineral Density in Patients on Maintenance Hemodialysis

BACKGROUND

Irisin is a circulating hormone-like myokine that plays an important role in bone metabolism. We performed a cross-sectional study to investigate whether serum irisin levels correlated with bone mineral density (BMD) in patients on maintenance hemodialysis (MHD).

METHODS

Blood samples were obtained from 80 patients on MHD, and serum irisin concentrations were determined using a commercially available enzyme-linked immunosorbent assay. BMD was measured by dual-energy X-ray absorptiometry of the L2-L4 vertebrae.

RESULTS

In the study cohort, 10 (12.5%) and 19 (23.8%) patients had osteoporosis and osteopenia, respectively, and 51 (63.75%) patients had normal BMD. Lumbar T-score was negatively associated with body height (P=0.010), body weight (P=0.002), body mass index (BMI, P=0.010), and serum irisin (P < 0.001) and was positively associated with advanced age (P=0.031), female sex (P=0.001), alkaline phosphatase (ALP, P=0.010), urea reduction rate (P=0.018), and fractional clearance index for urea (P=0.020). Multivariable forward stepwise linear regression analysis revealed that high serum logarithmically transformed irisin (log-irisin, β = 0.450, adjusted R 2 change = 0.258; P < 0.001), female sex (β = -0.353, adjusted R 2 change = 0.134; P < 0.001), and serum ALP level (β = -0.176, adjusted R 2 change = 0.022; P=0.049) were significantly and independently associated with lumbar BMD in patients on MHD.

CONCLUSIONS

In addition to female sex and serum ALP level, serum irisin level was positively associated with lumbar BMD in patients on MHD.

The level of N-terminal pro-brain natriuretic peptide depending on vascular wall condition and bone mass in postmenopausal women

Aim. To assess the relationship of serum N-terminal pro-brain natriuretic peptide (NT-proBNP) levels with vascular wall condition and bone mineral density (BMD) in postmenopausal women.

Material and methods. The cross-sectional study included 107 outpatients aged 45-82 years who signed informed consent. The inclusion criterion was a menopause during ≥1 year. The level of serum NT-proBNP was determined by electrochemiluminescence. BMD was assessed by dual energy x-ray absorptiometry. Intima-media thickness (IMT), the presence and number of atherosclerotic plaques were evaluated using carotid duplex scanning. Pulse wave velocity (PWV) and augmentation index were estimated by applanation tonometry. To assess 10-year cardiovascular risk, the SCORE high-risk charts were used. Using the Russian model of FRAX® score, 10-year fracture risk was assessed.

Results. NT-proBNP level in women with postmenopause >10 years was significantly higher than in those with postmenopause <5 years — 98,7 vs 56,3 pg/ml (p<0,001), but there was no independent relationship according to the regression analysis. According to multivariate regression analysis adjusted for age, menopause duration, systolic blood pressure, hypercholesterolemia, smoking, elevated C-reactive protein and interleukin-6 levels, there were independent relationship between the following parameters: NT-proBNP and IMT (β=2,38, p<0,03), NT-proBNP and PWV (β=1,76, p<0,001). NT-proBNP level in patients with osteoporosis was significantly higher than in women with normal bone mass (p<0,01). A negative correlation was observed between NT-proBNP and BMD of the proximal femur (r=-0,26, p<0,05), while the relationship between BMD of the lumbar vertebrae (L1-L4) and NT-proBNP did not reach significance. In multivariate regression analysis, this relationship has not been confirmed. A positive correlation was obtained between cardiovascular risk (SCORE) and NT-proBNP levels (r=0,28, p<0,001). NT-proBNP levels did not differ in women with a high and low 10-year risk of both major osteoporotic fractures and femoral fractures.

Conclusion. An independent relationship of NT-proBNP with vascular stiffness and preclinical atherosclerosis was demonstrated: IMT and PWV. This indicates the participation of NT-proBNP in the atherosclerosis development. The association of elevated NT-proBNP levels with osteoporosis is significant, but not independent, and is apparently related to other factors.

Corin is a key regulator of endochondral ossification and bone development via modulation of vascular endothelial growth factor A expression

Corin has been studied extensively within the vascular system and is known to regulate blood pressure. We have shown that corin is one of the most highly upregulated genes during osteogenic differentiation of human adipose-derived stem cells (hASCs). This study tested the hypothesis that, through modulation of angiogenic signalling pathways, corin is a critical regulator of osteogenic differentiation and endochondral ossification. In vitro, corin expression in hASC was suppressed via siRNA knockdown and vascular endothelial growth factor A (VEGF-A) expression was quantified via reverse transcription polymerase chain reaction. In vivo, a murine corin knockout model (female, 10 weeks) was used to determine the effect of corin deficiency on long bone development. Wild-type and corin knockout long bones were compared via haematoxylin and eosin staining to assess tissue characteristics and cellular organization, three-point bending to assess mechanical characteristics, and immunohistochemistry to visualize VEGF-A expression patterns. Corin knockdown significantly (p < 0.05) increased VEGF-A mRNA expression during osteogenic differentiation. In vivo, corin knockout reduced tibial growth plate thickness (p < 0.01) and severely diminished the hypertrophic region. Corin knockout femurs had significantly increased stiffness (p < 0.01) and maximum loads (p < 0.01) but reduced postyield deflections (p < 0.01). In corin knockout mice, VEGF-A expression was increased near the growth plate but was reduced throughout the tibial shaft and distal head of the tibiae. This is the first study to show that corin is a key regulator of bone development by modulation of VEGF-A expression. Further elucidation of this mechanism will aid in the development of optimized bone tissue engineering and regenerative medicine therapies.

Bone mineral density in older patients with chronic heart failure is related to NYHA classification: a retrospective study

PURPOSE

Discrepant results on relationship between chronic heart failure (CHF) and bone mineral density (BMD) have been reported and little has investigated the association between bone mass loss and New York Heart Association (NYHA) classification in CHF patients. This study aimed to assess whether BMD was associated with NYHA classification in older CHF patients.

METHODS

It was a retrospective study and included 1049 stable CHF patients aged over 60 years in Zhejiang Hospital. BMD and T-score at femoral neck (FN) and lumbar spines over L2-L4 regions were measured using Dual-Energy X-ray Absorptiometry. One-way ANOVA was used to compare continuous data of different NYHA functional class. Categorical variables were compared by Chi-square analysis. Pearson or Spearman correlation test was used to analyze the association between BMD and NYHA class, clinical parameters, lab data, etc. Significant variables in the correlation test (P < 0.05) were then tested by a multivariate linear regression test with stepwise subset selection to identify independent factors predicting BMD.

RESULTS

There were significant differences in FN BMD and T score across NYHA class I-IV, and that L2-L4 BMD and T score in patients in NYHA class IV were significantly lower when compared with CHF participants in NYHA classes I, II, and III. Moreover, Pearson correlation test and multivariate linear regression test demonstrated that there were statistically significant correlations between bone densitometric parameters and NYHA class.

CONCLUSIONS

There was a significant correlation between BMD and T-score at lumbar spines over L2-L4 and FN and NYHA class, implying that early screening and comprehensive intervention for osteoporosis (OP) might be helpful for patients with CHF.

Role of the protease corin in chondrogenic differentiation of human bone marrow-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) have the potency to differentiate into chondrocytes, osteocytes and adipocytes. Corin is a cardiac protease that activates the natriuretic peptides, thereby regulating blood volume and pressure. In addition to the heart, corin gene upregulation was reported in bone marrow- and adipose tissue-derived MSCs that underwent osteogenic differentiation. To date, the biological significance of corin expression in MSC differentiation remains unknown. In this study we isolated and cultured human bone marrow-derived MSCs that were capable of undergoing chondrogenic, osteogenic and adipogenic lineage differentiation. By reverse transcription polymerase chain reaction (RT-PCR) and immunostaining, we found that corin expression was upregulated when these MSCs underwent chondrogenic, osteogenic and adipogenic differentiation. The upregulation of corin expression was most significant in the cells undergoing chondrogenic lineage differentiation. Silencing corin gene expression by small hairpin RNA in the MSCs inhibited chondrogenic, but not osteogenic and adipogenic, differentiation. These results suggest a novel function of corin in MSC differentiation and chondrocyte development.

Inverse Association Between Serum Osteoprotegerin and Bone Mineral Density in Renal Transplant Recipients

BACKGROUND

Osteoprotegerin (OPG) has pleiotropic effects on bone metabolism as well as endocrine function. Our aim was to evaluate the relationship between bone mineral density (BMD) and serum OPG concentration in renal transplant recipients.

METHODS

Fasting blood samples were obtained from 69 renal transplant recipients. BMD was measured in lumbar vertebrae (L2-L4) by dual-energy X-ray absorptiometry. Eight patients (11.6%) had BMD values indicative of osteoporosis, 28 patients (40.6%) had BMD values indicative of osteopenia, and 33 patients had normal BMD values. Increased serum OPG levels (P < .001), decreased body mass index (BMI) (P = .033), and decreased body weight (P = .010) were significantly correlated with low lumbar T-score cut-off points between groups (normal, osteopenia, and osteoporosis).

RESULTS

Women had significantly lower lumbar BMD values than men (P = .013). Menopause (P = .005), use of tacrolimus (P = .020), and use of cyclosporine (P = .046) were associated with lower lumbar BMD in renal transplant recipients. Univariate linear regression analysis revealed that lumbar BMD was positively correlated with height (P = .016), body weight (P = .001), and BMI (P = .015) and negatively correlated with age (P = .039) and log-OPG (P = .001). Multivariate linear regression analysis revealed that log-OPG (β: -0.275, R(2) change = 0.154, P = .014), body weight (β: 0.334, R(2) change = 0.073, P = .004), and age (β: -0.285, R(2) change = 0.079, P = .008) were independent predictors of lumbar BMD values in renal transplant recipients.

CONCLUSIONS

Serum OPG concentration correlated negatively with lumbar BMD values in renal transplant recipients.