The impact of LRP5 polymorphism (rs556442) on calcium homeostasis, bone mineral density, and body composition in Iranian children

Age-, Sex-, and Puberty-Associated Reference Intervals for Lipid Profile in Iranian Children and Adolescents

Childhood dyslipidemia is considered a major worldwide health issue. Identification of children with dyslipidemia is notably essential for healthcare providers in establishing and releasing recommendations for the management and prevention of future CVD. In the present study, we provided reference values for the lipid profile from Kawar (a city in the south of Iran) cohort of healthy children and adolescents aged 9-18 years. 472 subjects (234 girls and 238 boys) contributed to the current prospective cohort study using a systematic random sample stratified by age. Fasting lipid levels were measured by enzymatic reagents. Dual-energyX-ray absorptiometry (DEXA) was used to evaluate puberty based on the Tanner stages. LMS Chart Maker and Excel software were used to construct the gender-specific reference plots showing the 3, 10, 25, 50, 75, 90, and 97th percentiles of BMI, cholesterol, TG, HDL, TC, LDL, and non-HDL. The outcomes revealed that concentrations of TC, LDL, and non-HDL were drastically greater in girls as compared to boys. TG increased with age in both genders, while HDL, TC, LDL, and non-HDL declined. We also observed that puberty was associated with higher lipid values in boys and girls except for TG in boys. Our study prepared age- and sex-specific reference intervals for the lipid profile in Iranian children and adolescents. Converted to age and gender percentiles, these reference intervals are expected to serve as an effective and consistent tool for doctors to identify dyslipidemia among children and adolescents.

LRP5 promotes cancer stem cell traits and chemoresistance in colorectal cancer

The overactivation of canonical Wnt/β-catenin pathway and the maintenance of cancer stem cells (CSCs) are essential for the onset and malignant progression of most human cancers. However, their regulatory mechanism in colorectal cancer (CRC) has not yet been well demonstrated. Low-density lipoprotein receptor-related protein 5 (LRP5) has been identified as an indispensable co-receptor with frizzled family members for the canonical Wnt/β-catenin signal transduction. Herein, we show that activation of LRP5 gene promotes CSCs-like phenotypes, including tumorigenicity and drug resistance in CRC cells, through activating the canonical Wnt/β-catenin and IL-6/STAT3 signalling pathways. Clinically, the expression of LRP5 is upregulated in human CRC tissues and closely associated with clinical stages of patients with CRC. Further analysis showed silencing of endogenous LRP5 gene is sufficient to suppress the CSCs-like phenotypes of CRC through inhibiting these two pathways. In conclusion, our findings not only reveal a regulatory cross-talk between canonical Wnt/β-catenin signalling pathway, IL-6/STAT3 signalling pathway and CD133-related stemness that promote the malignant behaviour of CRC, but also provide a valuable target for the diagnosis and treatment of CRC.

Lipoprotein receptor signalling in atherosclerosis

The founding member of the lipoprotein receptor family, low-density lipoprotein receptor (LDLR) plays a major role in the atherogenesis through the receptor-mediated endocytosis of LDL particles and regulation of cholesterol homeostasis. Since the discovery of the LDLR, many other structurally and functionally related receptors have been identified, which include low-density lipoprotein receptor-related protein (LRP)1, LRP5, LRP6, very low-density lipoprotein receptor, and apolipoprotein E receptor 2. The scavenger receptor family members, on the other hand, constitute a family of pattern recognition proteins that are structurally diverse and recognize a wide array of ligands, including oxidized LDL. Among these are cluster of differentiation 36, scavenger receptor class B type I and lectin-like oxidized low-density lipoprotein receptor-1. In addition to the initially assigned role as a mediator of the uptake of macromolecules into the cell, a large number of studies in cultured cells and in in vivo animal models have revealed that these lipoprotein receptors participate in signal transduction to modulate cellular functions. This review highlights the signalling pathways by which these receptors influence the process of atherosclerosis development, focusing on their roles in the vascular cells, such as macrophages, endothelial cells, smooth muscle cells, and platelets. Human genetics of the receptors is also discussed to further provide the relevance to cardiovascular disease risks in humans. Further knowledge of the vascular biology of the lipoprotein receptors and their ligands will potentially enhance our ability to harness the mechanism to develop novel prophylactic and therapeutic strategies against cardiovascular diseases.

The rs2302685 polymorphism in the LRP6 gene is associated with bone mineral density and body composition in Iranian children

BACKGROUND

Some 60-80% of the variability in bone mineral density (BMD) is determined by genetic factors. In the present study, we investigated the impact of the rs2302685 polymorphism of LRP6 on BMD and body composition in Iranian children.

METHODS

In total, 200 children (101 boys and 99 girls) were enrolled in the study. Body composition and BMD were computed using the Hologic DXA System (Hologic, Marlborough, MA, USA). The single nucleotide polymorphism of LRP6 rs2302685 (V1062I) was determined using a polymerase chain reaction/restriction fragment length polymorphism. A generalized linear model was performed to find the association between LRP6 polymorphisms, BMD and body composition in two adjusted models.

RESULTS

In model 1, a significant difference was found between LRP6 (rs2302685) polymorphism, trochanteric BMD (p = 0.007), intertrochanteric BMD (p = 0.007), total fat (p = 0.001), total fat (%) (p = 0.034), total lean mass (p = 0.031), total Lean + BMC (p = 0.036) and total mass (p = 0.001). In model 2, LRP6 (rs2302685) polymorphisms showed a significant effect on the trochanteric BMD (p = 0.005), intertrochanteric BMD (p = 0.005), total fat (p = 0.001), total fat (%) (p = 0.013) and total mass (p = 0.01). Total fat, total fat (%) and total body mass were higher in subjects with the CC genotype compared to the TT/CT genotype, whereas total lean mass and total Lean + BMC were higher in the TT/CT genotype.

CONCLUSIONS

The present study shows that the LRP6 polymorphism may be associated with body composition and BMD in Iranian children.

Influence of Estrogen Receptor Alpha Polymorphism on Bone Mineral Density in Iranian Children

BACKGROUND

Bone mass acquisition in childhood is directly linked to adult bone mineral density (BMD) and fracture risk. BMD is a heritable trait, more than 70% of its variability among a population is affected by genetic factors.

OBJECTIVES

In the present study, we wanted to investigate the association between estrogen receptor alpha (ESR1) polymorphisms, PvuII (rs2234693) and XbaI (rs9340799), and bone area, bone mineral content (BMC), and BMD of the lumbar spine, femoral neck, and also of the total body less the head in Iranian children.

METHODS

The ESR1 gene PvuII and XbaI genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. Bone area, BMC, BMD, and bone mineral apparent density (BMAD) were assessed by dual-energy X-ray absorptiometry (DEXA). Linear regression was carried out to examine the effects of the ESR1 (PvuII and XbaI) polymorphisms on DEXA outputs when adjusted for confounding factors (i.e., age, sex, BMI, and pubertal stage) in 3 models.

RESULTS

ESR1 (PvuII) gene polymorphisms (CT vs. CC) showed significant effects on the BMC of the total body less the head in all 3 models. For ESR1 (XbaI), individuals with the AG genotype had higher lumbar spine BMD and lumbar spine BMAD compared to other genotypes.

CONCLUSIONS

It seems that the PvuII and XbaI polymorphisms of ESR1 could be associated with BMC and BMD variation in Iranian children and adolescents.

Association between serum uric acid and bone health in adolescents

Previous studies are suggestive of the protective role of uric acid on bone in the middle-aged and elderly. Whether this association exists in younger individuals has not been examined. This investigation showed a significant positive association between serum uric acid and bone parameters among Iranian adolescents.

INTRODUCTION

Uric acid (UA) might be linked to bone health, but it is unclear whether its effects on bone are limited to certain population subgroups. This study is aimed at investigating the correlation between serum uric acid levels and bone mineral density (BMD) in Iranian adolescents.

METHODS

This cross-sectional study was conducted on 413 (221 girls and 192 boys) Iranian adolescents aged 9-19 years. An analysis of anthropometric, biochemical parameters and bone density was performed on the participants. Measurements included serum uric acid, calcium, phosphorus, alkaline phosphatase, albumin, and vitamin D. They were divided according to their serum UA into the low UA group who had UA ≤ 6 mg/dL and the high UA group with UA > 6 mg/dL. BMD and bone mineral content (BMC) were measured in the total body, lumbar spine, and left femoral neck, using dual energy X-ray absorptiometry (DXA), and bone mineral apparent density (BMAD) was calculated.

RESULTS

A Pearson correlation analysis revealed a significant correlation between UA and bone parameters. In multiple regression analyses adjusted for potential confounders, serum UA was proven to be associated with BMD and BMC at all sites. There was no association between UA, serum calcium, and vitamin D concentrations.

CONCLUSION

Our study, as the first research on adolescents, demonstrated a higher bone density in those who had higher UA levels.

The association of LRP5 (rs556442) polymorphism with body composition and obesity in postmenopausal women

AIM

The main of this study was to investigate the association between the rs566442 (V1119V) coding polymorphism of Low-density lipoprotein receptor-related protein 5 (LRP5) with obesity and basal metabolic rate in Iranian postmenopausal women.

METHODS

This cross-sectional study was performed on 350 postmenopausal women with a mean age of 57.8 years (SD ± 6.14). Body composition was analyzed by bioelectrical impedance analysis (BIA) resistance. Obesity was defined based on Body mass index (BMI) ≥30 kg/m2. To determine the genotype of SNP (rs556442), PCR-RFLP assay was performed and confirmed by sequencing. DNA samples from participants were genotyped using the RFLP-PCR method.

RESULTS

Among the study population 37.1% (130) were obese. G allele had minor-allele frequency of 0.38% in our population. The frequency of genotypes in our study population was 12.9% (45 person) GG, 35.7% (125 person) AA and 51.4% (180) GA. After adjusting age and menopausal age, only basal metabolic rate showed significantly higher in GG group compare to other groups (p = 0.02). Our data showed basal metabolic rate was higher in obese women with GG genotype in comparison to obese women with AG and AA genotypes.

DISCUSSION

The findings of this study suggest that the GG genotype of SNP (rs556442) could protective role in obese women through the association with BMR.

Bone mineral density loss in ambulatory children with epilepsy in spite of using supplemental vitamin D in Southern Iran: a case-control study

Epilepsy might have adverse effect on bone density due to underlying disease, drugs, vitamin D deficiency, immobilization and malnutrition. We investigated the bone mineral density in ambulatory vitamin-D supplemented children with epilepsy. This case-control study was conducted on 90 epileptic children aged 11.4 ± 3.3 years, and age and gender matched controls in pediatric neurology clinics of Shiraz, in Southern Iran, 2016. Anthropometric measurements, puberty, sun exposure, physical activity and biochemical variables were assessed. Bone mineral density was evaluated by dual-energy X-ray absorptiometry method. Data were analyzed by SPSS.v21. Prevalence of low bone mass in femur was more in patients (27%) than the controls (9%) (P value = 0.002). Age, weight Z score and height Z score were the most significant associated factors on lumbar BMD, BMAD, and femur BMD. Seizure duration and how it responded to anticonvulsants were the most associated factors with both lumbar and femur bone density. Sodium valproate and carbomazepin usage had negative association with lumbar Z score (beta = - 0.216, P = 0.017 and beta = - 0.336, P = 0.027, respectively). We hypothesized that epilepsy per se could affect bone density by an unknown pathophysiology, which was independent from vitamin D deficiency, effects of anticonvulsant and physical activity.

Influence of LRP5 (rs556442) polymorphism on insulin resistance in healthy Iranian children and adolescents

Background/aim

Genetic aspects play a role in insulin resistance in children. In this study, for the first time, the association of LRP5 (rs556442) polymorphism and insulin resistance in Iranian children and adolescents was investigated.

Materials and methods

The study population comprises children and adolescents aged 9–18 years. Anthropometric and biochemical parameters were assessed. Insulin resistance/sensitivity was determined by the quantitative insulin sensitivity check index (QUICKI), homeostasis model assessment-insulin resistance (HOMA-IR), insulin-to-glucose ratio, McAuley index, revised McAuley index, fasting insulin resistance index (FIRI), and Bennett’s index. LRP5 (rs566442) single nucleotide polymorphism (SNP) was identified using restriction fragment length polymorphism (RFLP). Linear regression analysis was used to determine the association between the LRP5 polymorphism (rs556442) and insulin sensitivity indexes.

Results

Significant differences were found between GG genotype vs. AG/AA genotypes for McAuley index (P = 0.049) and revised McAuley index (P = 0.044) when adjusted for interaction factors (age, sex, and puberty) in regression models. No significant association was found between LRP5 (rs566442) and other insulin resistance indexes. Also, LRP5 (rs566442) did not show a significant impact on biochemical parameters.

Conclusion

This study showed that LRP5 polymorphism (rs556442) was associated with insulin resistance in Iranian children and adolescents.

Association of Vitamin D Receptor BsmI Gene Polymorphism with BMD Z-Score in Iranian Children and Adolescents (9 - 18 Years Old)

BACKGROUND

The vitamin D receptor (VDR) gene variants are known as the main risk factor for low bone mass.

OBJECTIVES

In this study, the association of vitamin D receptor genetic variants, BsmI (rs1544410) and FokI (rs2228570), with bone mass in Iranian children and adolescents, was evaluated.

METHODS

The study population comprised of children and adolescents aged between 9 to 18 years (FokI: 123 boys and 120 girls, BsmI: 108 boys and 110 girls). Vitamin D, calcium, phosphorus, total cholesterol (TC), High-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) concentrations were assayed. Bone mineral density and body composition parameters were measured by the Hologic system DXA. BMD Z-score ≤ -2 was considered as low bone density for chronologic age. PCR-restriction fragment length polymorphism was done for genotyping of BsmI and FokI polymorphisms. The association between VDR variants and bone mineral density was investigated using logistic regression analysis.

RESULTS

No significant differences in body composition and biochemical parameters were detected among the evaluated VDR genotypes. For VDR BsmI, the mean values for Z-score of the lumbar spine, neck, inter and total femur was greater in the bb genotype compared to BB and Bb genotypes. Logistic regression analysis revealed a significant association between femoral neck Z-score and VDR BsmI genotypes in an additive genetic model (unadjusted model (P = 0.035; Bb vs. bb), model 1 (adjusted for age and sex, P = 0.021; Bb vs. bb), model 2 (adjusted for age, sex and BMI, P = 0.013; Bb vs. bb) and model 3 (adjusted for age, sex, BMI and puberty, P = 0.011; Bb vs. bb, P = 0.049; BB vs. bb)) and dominant genetic model ((unadjusted model, P = 0.033; BB+Bb vs. bb), model 1 (adjusted for age and sex, P = 0.023; BB+Bb vs. bb), model 2 (adjusted for age, sex and BMI, P = 0.012; BB+Bb vs. bb and model 3 (adjusted for age, sex, BMI and puberty, P = 0.012; BB+Bb vs. bb)).

CONCLUSIONS

This investigation indicated that VDR BsmI polymorphism may be associated with BMD Z-score of the femoral neck but not the lumbar spine, in Iranian children and adolescents.

Effect of Cholecalciferol therapy on serum FGF23 in vitamin D deficient patients: a randomized clinical trial

INTRODUCTION

Fibroblast growth factor-23 plays an important role in regulating systemic phosphate homeostasis, and vitamin D metabolism. However, the effect of Cholecalciferol therapy on FGF₂₃ serum level in patients with vitamin D deficiency has not been studied, yet.

MATERIALS AND METHODS

This is a double-blind, randomized clinical trial on 119 vitamin D deficient patients in 2016. Biochemical variables of treatment and placebo groups were analyzed after 12 weeks of 50,000 IU of Cholecalciferol vs. placebo therapy once a week, by SPSS18.

RESULTS

After Cholecalciferol therapy, delta of serum PTH in treatment group was less than the controls (P < 0.001). However, delta values of serum 25(OH)D₃, 1,25(OH)₂D₃ and FGF₂₃ in vitamin D treated group were more than the placebo-treated ones (P < 0.001, P = 0.002, and P = 0.04, respectively). Moreover, FGF₂₃ serum level in treatment group was associated with serum calcium (P = 0.005, r = -0.256), and serum 1,25(OH)₂D₃ (P < 0.001, r = 0.529).

CONCLUSIONS

We propose that in these patients 1,25(OH)₂D₃ has a positive association with serum FGF₂₃, and hypostasized that serum calcium might be a down regulator of serum FGF₂₃.

Investigating the bone mineral density in children with solid tumors in southern Iran: a case-control study

Along with increasing childhood cancer survival, there is increasing concern about its chronic complications. We showed that 20.5 and 45.9% of children with solid tumors in southern Iran had low bone mass for chronological age in lumbar and femoral area, which was associated with serum ferritin and hemoglobin. 52.4% of these children had vitamin D deficiency, as well.

PURPOSE/INTRODUCTION

Along with increasing the childhood cancer survival, there is increasing concern about the chronic complications of the disease and the related therapies. This study aims to compare the vitamin D status and bone mineral apparent density (BMAD) of these children with healthy ones and assess some possible associated factors.

METHOD

This case-control study enrolled 50 children with solid tumors and their age- and sex-matched controls. Dual-energy X-ray absorptiometry was used to assess bone mineral density. Body mass index, puberty, physical activity, sun exposure, and biochemical data were assessed.

RESULTS

52.4% of children with solid tumors had vitamin D deficiency, and there was no significant difference between the prevalence of vitamin D deficiency in patients and controls (P = 0.285). The prevalence of low bone mass for chronological age in lumbar area was 20.5 and 12.5% in patients and controls, respectively (P = 0.399). Lumbar spine BMD was associated with hemoglobin level (r = 0.468, P = 0.049), while low bone mass in femoral neck was associated with serum ferritin (859 ± 1037 in low bone mass vs. 178 ± 264 in without low bone mass, P = 0.039).

CONCLUSION

Vitamin D deficiency and low bone mass are prevalent among Iranian children with solid tumors. Future studies are warranted to investigate the best strategies to prevent and treat vitamin D deficiency and low bone mass in children surviving cancer.

Evaluation of bone mineral density in children with sickle-cell anemia and its associated factors in the south of Iran: a case-control study

Sickle-cell anemia is a hereditary hemoglobin disorder among children. We showed that the low bone mass is prevalent among these children, and it has a negative association with hemoglobin. In spite of using supplementary 200 IU/day vitamin D, 59.6% of children with sickle-cell anemia are vitamin D deficient. We suggest that early diagnosis and treatment of this problem could improve the bone health in them.

The rs3736228 polymorphism in the LRP5 gene is associated with calcaneal ultrasound parameter but not with body composition in a cohort of young Caucasian adults

The aim of the present study was to investigate the possible influence of low-density lipoprotein receptor-related protein 5 (LRP5) and sclerostin (SOST) genes as genetic factors contributing to calcaneal quantitative ultrasound (QUS) and body composition variables in a population of young Caucasian adults. The study population comprised a total of 575 individuals (mean age 20.41years; SD 2.36) whose bone mass was assessed through QUS to determine broadband ultrasound attenuation (BUA, dB/MHz). Body composition measurements were performed using a body composition analyser. Seven single-nucleotide polymorphisms (SNPs) of LRP5 (rs2306862, rs599083, rs556442 and rs3736228) and SOST (rs4792909, rs851054 and rs2023794) were selected as genetic markers and genotyped using TaqMan OpenArray^® technology. Linear regression analysis was used to test the possible association of the tested SNPs with QUS and body composition parameters. Linear regression analysis revealed that the rs3736228 SNP of LPR5 was significantly associated with BUA after adjustment for age, sex, weight, height, physical activity and calcium intake (P = 0.028, β (95% CI) = 0.089 (0.099-1.691). For the remaining SNPs, no significant association with the QUS measurement was observed. Regarding body composition, no significant association was found between LRP5 and SOST polymorphisms and body mass index, total fat mass and total lean mass after adjustment for age and sex as covariates. We concluded that the rs3736228 LRP5 genetic polymorphism influences calcaneal QUS parameter in a population of young Caucasian adults. This finding suggests that LRP5 might be an important genetic marker contributing to bone mass accrual early in life.

Investigating the Prevalence of Low Bone Mass in Children of Southern Iran and Its Associated Factors

BACKGROUND

Improving peak bone mass and bone strength in the first years of life and enhancing it during young adulthood could prevent osteoporosis and fractures in the last years of life. We evaluated the prevalence of low bone mass in the lumbar and femoral neck and its associated factors in southern Iranian children.

METHODS

This is a cross-sectional study on healthy Iranian children aged 9 - 18 years old during 2011 - 2012. Dual energy X-ray absorptiometry (DEXA) was used for measuring bone mineral density (BMD). BMD Z-score ≤ -2 was considered as low. Anthropometric data, physical activity, sun exposure, puberty, and mineral biochemical parameters were assessed. Data were analyzed using SPSS v.15.

RESULTS

477 normal children, including 236 (49.5%) girls and 241 (50.5%) boys, aged 13.8 ± 2.7 years were enrolled. Prevalence of low bone mass (LBM) in the femoral and lumbar region was 10.7% and 18.7%, respectively. The prevalence of LBM in femur of girls is twice more than boys. Fat mass index, BMI Z-score, and physical activity were associated with lumbar low bone mass. BMI Z-score and physical activity were associated with femoral low bone mass.

CONCLUSIONS

High prevalence of low bone mineral density in children 9 to 18 years in south of the country is concerned and is needed to plan for prevention and treatment. BMI-Z score, fat mass index, and physical activity were the 3 most important preventive factors in developing low bone mass in children.

Polymorphism in LRP5 (rs556442) is associated with higher TG levels in Iranian children

BACKGROUND

Wnt signalling/LRP5 is involved in adipogenesis by down-regulating adipogenic transcription factors. Therefore polymorphisms in components of this pathway may lead to metabolic disorders.

AIM

This study tested the impact of LRP5 polymorphism on lipid profile in Iranian children.

METHODS

The study population was comprised of 9-18 year old children (125 boys, 137 girls). Total cholesterol (TC), High Density Lipoprotein (HDL), Low-Density Lipoprotein (LDL), Non-HDL cholesterol and Triglyceride (TG) levels were checked. Body composition was measured by the Hologic system DXA. PCR/restriction fragment length polymorphism (RFLP) was done for LRP5 (rs556442) genotyping. Multiple association analyses for TG level and genotype frequencies were assessed using logistic regression analysis, with adjustment for age, sex, BMI and puberty.

RESULTS

The results revealed that LRP5 (rs556442) had a significant influence on TG levels in unadjusted analysis and when adjusted for interacting factors. Higher TG levels were observed in AA/AG genotype of rs566442 in comparison to GG genotype (OR = 2.028, 95% CI = 0.997-4.127, p =  0.049).

CONCLUSION

It is concluded that allele A has an important impact on increasing TG level in LRP5 in the studied population.

Relative Importance of Lean and Fat Mass on Bone Mineral Density in Iranian Children and Adolescents

BACKGROUND

Body weight is made up of lean and fat mass and both are involved in growth and development. Impression of these two components in bone density accrual has been controversial.

OBJECTIVES

The aim of this study was to evaluate the relationship between fat and lean mass and bone density in Iranian children and adolescents.

PATIENTS AND METHODS

A cross-sectional study was performed on 472 subjects (235 girls, 237 boys) aged 9-18 years old in Fars Province. The participants' weight, height, waist circumference, stage of puberty, and level of physical activity were recorded. Bone Mineral Content (BMC), Bone Mineral Density (BMD), total body fat and lean mass were measured using dual-energy X-ray absorptiometry.

RESULTS

Results showed that 12.2% of boys and 12.3% of girls were overweight and 5.5% of boys and 4.7% of girls were obese. Obese individuals had greater total body BMD (0.96 ± 0.11) than normal-weight ones (0.86 ± 0.11) (P < 0.001). We found the greatest correlation between total body BMD and total body lean mass (R = 0.78. P < 0.001) and the least correlation with total body fat percentage (R = 0.03, P = 0.44). Total lean mass in more active boys was 38.1 ± 10.9 and in less active boys was 32.3 ± 11.0 (P < 0.001). The results of multiple regression analysis showed that age and total body lean mass were independent factors of BMD in growing children and adolescents.

CONCLUSIONS

These findings suggest that lean mass was the most important predictor of BMD in both genders. Physical activity appears to positively impact on lean mass and needs to be considered in physical education and health-enhancing programs in Iranian school children.