Visfatin and its genetic variants are associated with obesity-related morbidities and cardiometabolic risk in severely obese children

Correlation Analysis of NAMPT rs61330082 Polymorphism in Type 2 Diabetes Mellitus Combined with Hypertension

Introduction

This study aimed to investigate the association of Nicotinamide phosphoribosyl transferase (NAMPT) rs61330082 polymorphism with co-morbid hypertension (HTN) and the progression of hypertension in Chinese patients with type 2 diabetes mellitus (T2DM).

Methods

A total of 453 T2DM patients were genotyped for the polymorphism of rs61330082 using SNP-scan high-throughput technology. These patients were divided into T2DM group (261 patients) and T2DM combined with hypertension group (T2MH, 192 patients). The T2MH group was further categorized into Grade I, Grade II, and Grade III based on the results of the Hypertension Grade Score. Peripheral blood plasma urea, plasma creatinine, renin-angiotensin system (RAS) indexes, and lipid biochemistry indexes were measured in patients and analyzed in relation to NAMTP polymorphisms.

Results

We found that the presence of the NAMPT rs61330082-AA genotype was associated with a significantly increased risk of developing higher-grade hypertension in patients with T2MH. In addition, the A allele of the NAMPT rs61330082 gene displayed more associated in developing a higher grade of hypertension compared to the G allele. Also, the level of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-c) increased with hypertension grade in the NAMPT rs61330082-GG genotype.

Conclusion

NAMPT rs61330082 polymorphism was significantly associated with the progression of hypertension grade in T2MH patients and also affected plasma creatinine and LDL-c levels.

Fibroblast growth factor-21 and Visfatin as potential predictors for metabolic risk factors in obese children

Fibroblast growth factor-21 (FGF-21) and Visfatin are associated with obesity. However; reviewing the literature; no studies were found to assess their role as potential markers for the metabolic disorders related to obesity in children. Assess the relations between serum FGF-21 and Visfatin with obesity and its metabolic disorders, and their use as potential predictors for metabolic risk factors in a sample of Egyptian obese children. This cross-sectional study included 111 Egyptian children (45 males and 66 females); aged 6-10 years to avoid the effect of puberty (prepubertal). The exclusion criteria (by full History taking and clinical examination) were the presence of any sign of puberty according to Tanner stage, the presence of identified causes of obesity (genetic syndromes, chromosomal or endocrinal disorders), chronic diseases (cardiovascular, gastrointestinal, and respiratory), or drug use like steroids; that would interfere with the type of obesity and affect the normal growth of the children. Also, any child with a BMI between 85 and 95th percentiles (overweight) was excluded from the study. All participating obese children were suffering from exogenous simple obesity. They were classified according to their body mass index (BMI) percentiles into 72 obese (BMI ≥ 95th), and 39 control non-obese ones (BMI > 15th to < 85th), based on the Egyptian Growth Charts for children and adolescents. Ethical approvals were granted from both the Ethics Committee of the "National Research Centre" and the "Faculty of Postgraduate Childhood Studies" (Approval No. 17/125). Also, informed written consent was taken from either of the parents and assent from the participating children. They were subjected to blood pressure assessment, anthropometric measurements (weight [Wt], height [Ht], BMI, waist [WC], and hip [HC] circumferences), and laboratory evaluation (Visfatin, FGF-21, LDL, HDL, TG, cholesterol, fasting glucose, insulin, and calculation of HOMA-IR). Mann-Whitney test and Spearman's correlation test were applied. Obese children had significantly higher values than control ones regarding all the studied clinical (SBP, DBP), anthropometric parameters (Wt, Ht, BMI, WC, and HC), FBG, Insulin, HOMA-IR, Visfatin, and FGF-21, and had significantly lower values regarding HDL and Cholesterol. Among obese children, both FGF-21 and Visfatin had significant negative correlations with BMI and HC. At the same time, serum FGF-21 had a highly significant positive correlation with HDL. Visfatin and FGF-21 had highly significant positive correlations with each other. In the control group, both serum Visfatin or FGF-21 had insignificant correlations with each other and with all the studied clinical and anthropometric parameters. FGF-21 and Visfatin are related to the obesity markers, but they cannot be used as potential predictors for metabolic disturbance in obese prepubertal children; both had insignificant correlations with the metabolic risk factors.

Hormonal Determinants of Growth and Weight Gain in the Human Fetus and Preterm Infant

The factors controlling linear growth and weight gain in the human fetus and newborn infant are poorly understood. We review here the changes in linear growth, weight gain, lean body mass, and fat mass during mid- and late gestation and the early postnatal period in the context of changes in the secretion and action of maternal, placental, fetal, and neonatal hormones, growth factors, and adipocytokines. We assess the effects of hormonal determinants on placental nutrient delivery and the impact of preterm delivery on hormone expression and postnatal growth and metabolic function. We then discuss the effects of various maternal disorders and nutritional and pharmacologic interventions on fetal and perinatal hormone and growth factor production, growth, and fat deposition and consider important unresolved questions in the field.

Genetic Associations of Visfatin Polymorphisms with EGFR Status and Clinicopathologic Characteristics in Lung Adenocarcinoma

Lung adenocarcinoma (LUAD) is the most common histologic type of lung cancer. Mutations of the epidermal growth factor receptor (EGFR) gene are among the most common genetic alterations in LUAD and are the targets of EGFR tyrosine kinase inhibitors. The enzyme visfatin is involved in the generation of the oxidized form of nicotinamide adenine dinucleotide (NAD⁺) and regulation of intracellular adenosine triphosphate (ATP), critical processes in cancer cell survival and growth. This study explored the relationship between visfatin single nucleotide polymorphisms (SNPs) with EGFR status and the clinicopathologic development of LUAD in a cohort of 277 Taiwanese men and women with LUAD. Allelic discrimination of four visfatin SNPs rs11977021, rs61330082, rs2110385 and rs4730153 was determined using a TaqMan Allelic Discrimination assay. We observed higher prevalence rates of advanced (T3/T4) tumors and distant metastases in EGFR wild-type patients carrying the rs11977021 CT + TT and rs61330082 GA + AA genotypes, respectively, compared with patients carrying the CC and GG genotypes. EGFR wild-type patients carrying the rs11977021 CT + TT genotypes were also more likely to develop severe (stage III/IV) malignancy compared with patients carrying the CC genotype. An analysis that included all patients found that the association persisted between the rs11977021 CT + TT and rs61330082 GA + AA genotypes and the development of T3/T4 tumors compared with patients carrying the rs11977021 CC and rs61330082 GG genotypes. In conclusion, these data indicate that visfatin SNPs may help to predict tumor staging in LUAD, especially in patients with EGFR wild-type status.

Association of serum levels of Visfatin, Intelectin-1, RARRES2 and their genetic variants with bone mineral density in postmenopausal females

BACKGROUND

Adipokines are engaged in bone physiology and regulate bone mineral density (BMD) by playing protective or cynical role in bone metabolism. The study is designed to measure and compare BMD, adipokines (retinoic acid receptor responder protein-2 RARRES2, visfatin and Intelectin-1) and their genetic variants in postmenopausal osteoporotic, osteopenic and non-osteoporotic females.

METHODS

This comparative study included postmenopausal non-osteoporotic (n=72), osteopenic (n=72) and osteoporotic (n=100) females with two years of amenorrhea and age between 50 to 70 years. Gold standard DXA was used to measure BMD. Hardy-Weinberg equilibrium was established. Kruskal-Wallis test for comparisons, logistic and multivariate regression analysis were used to rule out the predictors of BMD.

RESULTS

On comparing the three groups, significant differences were observed in serum RARRES2 (p <0.001) and serum visfatin (p=0.050). The significant positive predictor of BMD at lumbar spine and total hip was serum visfatin. BMD at right and left femoral neck was predicted negatively by serum chemerin while BMD at left femoral neck was also predicted positively by serum calcium levels. There was significant difference in BMD at right femoral neck (p = 0.033) between rs7806429 genotypes. The odds of having low BMD increases with increasing serum levels of chemerin and decreasing serum levels of visfatin and calcium.

CONCLUSION

The adipokines RARRES2 and visfatin are associated with BMD. RARRES2 is an independent negative and visfatin is positive predictor of BMD in postmenopausal females. BMD at right femoral neck was significantly low in RARRES2 rs7806429 TC heterozygotes.

Serum Visfatin Levels in Nonalcoholic Fatty Liver Disease and Liver Fibrosis: Systematic Review and Meta-Analysis

(1) Background: Recently, adipokines, including visfatin, have been studied in nonalcoholic fatty liver disease (NAFLD). Several studies evaluated visfatin levels in NAFLD, the presence and severity of hepatic steatosis, liver fibrosis, lobar inflammation, nonalcoholic steatohepatitis (NASH), and gender differences. However, inconclusive results have been reported. Accordingly, we performed a systematic review and meta-analysis, aiming to address these gaps in evidence. (2) Methods: We performed a systematic electronic search on PubMed, EMBASE, and Cochrane Library using predefined keywords. Diagnosis of NAFLD by liver biopsy or imagistic investigations was accepted. Full articles satisfying our inclusion and exclusion criteria were included. NHLBI quality assessment tools were used to evaluate included studies. The principal summary outcome was the mean difference in visfatin levels. (3) Results: There were 21 studies involving 1923 individuals included in our qualitative assessment, while 14 studies were included in the quantitative assessment. No statistical significance was found assessing visfatin levels in NAFLD [3.361 (95% CI -0.175-6.897)], simple steatosis [7.523 (95% CI -16.221-31.267)], hepatic steatosis severity [-0.279 (95% CI -1.843-1.285)], liver fibrosis [4.133 (95% CI -3.176-11.443)], lobar inflammation [0.358 (95% CI -1.470-2.185)], NASH [-2.038 (95% CI -6.839-2.763)], and gender [(95% CI -0.554-0.556)]. (4) Conclusions: In conclusion, visfatin levels are not associated with NAFLD, presence or severity of hepatic steatosis, liver fibrosis, lobar inflammation, NASH, and gender. However, due to the limited methodological quality of the included studies, results should be interpreted with caution.

Serum visfatin level as a noninvasive marker for nonalcoholic fatty liver disease in children and adolescents with obesity: relation to transient elastography with controlled attenuation parameter

BACKGROUND

Obesity is associated with an increased risk of nonalcoholic fatty liver disease (NAFLD). Visfatin is an adipokine produced by visceral fat tissue and liver cells. Transient elastography with controlled attenuation parameter (CAP) noninvasively assesses liver fibrosis and steatosis.

AIM

To measure visfatin level in 80 children and adolescents with obesity as a potential biomarker for NAFLD and assess its relation to transient elastography.

METHODS

Abdominal ultrasound, liver stiffness and CAP measurements were performed for all patients. Fasting lipid profile, fasting blood glucose, insulin level, liver and kidney functions, coagulation profile and serum visfatin levels were assessed.

RESULTS

Among patients with obesity, 31 (38.8%) had NAFLD and 16 (20%) patients had elevated alanine aminotransferase (ALT), while 9 (11.2%) had both NAFLD and elevated ALT. Transient elastography showed that 12.5% had fibrosis stage F1, 2.5% had F2 and another 2.5% had F3 while none had F4. Using CAP, 23.8, 13.8 and 17.5% had S1, S2 and S3, respectively. Serum visfatin levels were significantly elevated in all patients compared with nonobese controls. Higher visfatin levels were found among patients with dyslipidemia, NAFLD, elevated ALT and steatosis defined by CAP. Serum visfatin was related to the degree of fibrosis and steatosis. Visfatin cutoff value 18 ng/mL could significantly detect the presence of NAFLD with 83.9% sensitivity and 81.4% specificity. Serum visfatin was positively correlated to BMI, waist circumference, waist/hip ratio, ALT, total cholesterol, liver stiffness and CAP.

CONCLUSIONS

Visfatin could be a promising serum biomarker for monitoring liver disease among pediatric patients with obesity.

Implications of visfatin genetic variants in the metabolic profile of the Romanian pediatric population

Background: Conflictual results regarding the relationship between plasmatic level of visfatin and obesity could be explained by the influence of the gene variants involved in the synthesis or action of these hormones.

Objectives: The present study examined the potential implication of single nucleotide polymorphisms (SNPs) of nicotinamide phosphoribosyltransferase (NAMPT) gene that encodes visfatin, in obesity, in a Romanian pediatric population.

Method: A case-control study was conducted on a group of 213 children, divided into two: the case group - 130 overweight and obese children with BMI >1 SD, and the control group - 83 children with normal BMI. The variables analyzed were age, sex, anthropometric parameters, body composition based on bioimpedance analysis, lipid profile, visfatin and insulin plasmatic levels, rs4730153 and rs2302559 visfatin SNPs.

Results: Significant associations were not found between rs4730153 and rs2302559 visfatin SNPs and obesity. Regarding lipid metabolism, there are statistically significant differences between triglyceride levels according to NAMPT rs2302559 genotypes (p=0.045), with heterozygous genotype having the highest level of triglycerides, and also between cholesterol levels according to NAMPT rs4730153 genotypes (p=0.030), with carriers of heterozygote genotype having the highest level of cholesterol. There is a statistically significant difference between the studied parameters in the investigated groups, regarding cholesterol, in carrier of wild-type genotype of NAMPT rs2302559 (p=0.040) and carrier of wild-type genotype of NAMPT rs4730153 (p=0.036). We observed no association of NAMPT rs4730153 and rs2302559 with visfatin levels in the studied groups. Visfatin level was lower in the case group and was correlated with weight (p=0.042), abdominal circumference (p=0.010), waist to height ratio (p=0.040), but not with the elements of the metabolic profile.

Conclusion: NAMPT rs2302559 and rs4730153 polymorphisms do not seem to have a major impact in the development of obesity in children, however there may be an association with lipid profile, but further studies are needed..

SERUM BILIRUBIN CORRELATES WITH SERUM ADIPOKINES IN NORMAL WEIGHT AND OVERWEIGHT ASYMPTOMATIC ADULTS

Overweight and obesity are considered as chronic low-grade inflammation accompanied by imbalanced production of adipokines. The aim of this study was to elucidate the relationship between serum bilirubin, which is an endogenous antioxidant with anti-inflammatory activity, and pro- and anti-inflammatory serum adipokines in asymptomatic normal weight and overweight individuals. Healthy men and women aged 25-49 participated in this cross-sectional study. All participants underwent fasting serological measurements of adipokines, interleukin-6, tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP), total and direct serum bilirubin, and other biochemical parameters. Participants were divided into normal weight and overweight groups. We found a significant negative association between total bilirubin and CRP, TNF-α, visfatin and resistin values, and a significant positive association between total bilirubin and adiponectin values in both normal-weight and overweight groups. Importantly, after adjusting for body mass index, we also found a significant negative association between total serum bilirubin levels and both visfatin and CRP serum levels. Moreover, visfatin, resistin and CRP were predictors of the total serum bilirubin levels.

Neck circumference and clustered cardiovascular risk factors in children and adolescents: cross-sectional study

OBJECTIVE

Early detection of cardiovascular disease (CVD) risk factors, such as obesity, is crucial to prevent adverse long-term effects on individuals' health. Therefore, the aims were: (1) to explore the robustness of neck circumference (NC) as a predictor of CVD and examine its association with numerous anthropometric and body composition indices and (2) to release sex and age-specific NC cut-off values to classify youths as overweight/obese.

DESIGN

Cross-sectional study.

SETTING

23 primary schools and 17 secondary schools from Spain.

PARTICIPANTS

2198 students (1060 girls), grades 1-4 and 7-10.

MEASURES

Pubertal development, anthropometric and body composition indices, systolic and diastolic blood pressure (SBP and DBP, respectively), cardiorespiratory fitness, blood sampling triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), glucose and inflammatory markers. Homoeostasis model assessment (HOMA-IR) and cluster of CVD risk factors were calculated.

RESULTS

NC was negatively associated with maximum oxygen consumption (R2=0.231, P<0.001 for boys; R2=0.018, P<0.001 for girls) and adiponectin (R2=0.049, P<0.001 for boys; R2=0.036, P<0.001 for girls); and positively associated with SBP, DBP, TC/HDL-c, TG, HOMA, complement factors C-3 and C-4, leptin and clustered CVD risk factor in both sexes (R2 from 0.035 to 0.353, P<0.01 for boys; R2 from 0.024 to 0.215, P<0.001 for girls). Moreover, NC was positively associated with serum C reactive protein and LDL-c only in boys (R2 from 0.013 to 0.055, P<0.05).

CONCLUSION

NC is a simple, low-cost and practical screening tool of excess of upper body obesity and CVD risk factors in children and adolescents. Paediatricians can easily use it as a screening tool for overweight/obesity in children and adolescents. For this purpose, sex and age-specific thresholds to classify children and adolescents as normal weight or overweight/obese are provided.

Genetic associations of the visfatin G-948T polymorphism with obesity-related metabolic traits in an Iranian population

Background:

Obesity is a global public health problem. Visfatin, as an adipocytokine, is coded by a gene known as nicotinamide phosphoribosyltransferase. So far, results were conflicted regarding correlations of visfatin with obesity and metabolic variables. The present study aimed to explore the association between G-948T polymorphism of visfatin gene with obesity and lipid profile in a nationally representative sample of Iranian population.

Materials and Methods:

In this case–control study, we assessed 129 randomly selected patients with obesity and 182 healthy normal weight controls from participants of Isfahan Healthy Heart Program. Genomic DNA was isolated from peripheral blood cells, and high-resolution melt polymerase chain reaction was performed to explore the presence of G-948T polymorphism.

Results:

T carriers “GT + TT” were statistically more frequent in the obese patients than the controls (P = 0.013; odds ratio = 1.9, 95% confidence interval = 1.1–3.1). The serum levels of total cholesterol and low-density lipoprotein cholesterol (LDL-C) were significantly different between T carriers and GG homozygote genotype (P = 0.03 and 0.02, respectively).

Conclusion:

We concluded that visfatin G-948T polymorphism was correlated with obesity, total cholesterol, and LDL-C levels in our population.

In-vitro function of upstream visfatin polymorphisms that are associated with adverse cardiometabolic parameters in obese children

BACKGROUND

Visfatin is an adipokine associated with glucose and lipid metabolism. We previously reported two visfatin upstream single nucleotide polymorphisms (SNPs), c.-3187G > A (rs11977021) and c.-1537C > T (rs61330082), which were in perfect linkage disequilibrium, in a Singaporean cohort of severely obese children and are associated with visfatin level and adverse cardiometabolic parameters. We aim to functionally characterize the effect of c.-3187G > A and c.-1537C > T SNPs on basal transcriptional activity.

METHODS

A 1.6 kb and 3.7 kb upstream promoter region of the visfatin gene was amplified by polymerase chain reaction and separately cloned into luciferase reporter vectors. Successful clones were transfected into human embryonic kidney (HEK293T) and human breast carcinoma (MCF7) cells and in-vitro dual-luciferase assay was performed. Electrophoretic mobility shift assay (EMSA) was also conducted to examine the binding affinity between transcription factors and visfatin promoter sequences.

RESULTS

Variant promoter with only c.-1537C > T SNP did not show a change in transcriptional activity as compared to the wild type. However, variant promoter with both c.-3187G > A and c.-1537C > T SNPs showed a statistically significant increase of 1.41 fold (p < 0.01) in transcriptional activity. The longer 3.7kbp visfatin promoter sequence was also shown to have significantly higher transcriptional activity (p < 0.05) as compared to the shorter 1.6kbp visfatin promoter. Both c.-3187G > A and c.-1537C > T variants showed an increased binding with nuclear protein.

DISCUSSION AND CONCLUSIONS

We have demonstrated for the first time that visfatin variant promoter with both c.-3187G > A and c.-1537C > T SNPs result in an increase in transcriptional activity. This supports our previous finding and postulation that these SNPs contribute to elevated visfatin levels which may mediate higher triglyceride levels, severe systolic blood pressure and severe hypertension in obese children. These SNPs may co-operatively affect enhancer or silencer function to regulate transcriptional activity. In conclusion, this study shows that upstream visfatin SNPs could potentially affect phenotypic outcome in obese children through alteration of circulating visfatin level.

Genetic variant in visfatin gene promoter contributes to reduced risk of hepatocellular carcinoma in a Chinese population

Knowledge on the role of gene variants in the visfatin promoter region in the hepatitis B virus (HBV)-related liver diseases is limited. In this study, we genotyped two potentially functional single nucleotide polymorphisms (SNPs) in the visfatin promoter region, -1535C>T (rs61330082) and -3187G>A (rs11977021), in 120 HBV-related chronic hepatitis B (CHB) patients, 140 HBV-related liver cirrhosis (HBV-LC) patients, 243 HBV-related hepatocellular carcinoma (HBV-HCC) patients, and 224 asymptomatic HBV carriers. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated by logistic regression. The results showed subjects with a TT genotype of -1535C>T had a significantly decreased risk of HBV-HCC related to the CC and CC + CT genotypes (adjusted OR = 0.493, 95% CI = 0.313-0.778; OR = 0.535, 95% CI = 0.362-0.791, respectively). A lowered risk also appeared in the comparison between allele T and allele C (OR = 0.734, 95%, CI = 0.581-0.950). However, these associations existed only in people with Zhuang ethnicity, but not in people with Han ethnicity. There were no significant associations between -3187G>A polymorphisms and the risk of HBV-related liver diseases. Our results suggested that visfatin -1535C>T polymorphisms might be associated with decreased risk of HBV-HCC among the ethnic Zhuang population in Guangxi, China.

Visfatin serum level and expression in subcutaneous and visceral adipose tissue in prepubertal boys

BACKGROUND

The biological role of visfatin in humans, especially in eutrophic and healthy children, is not understood yet, except for its link to obesity-related disorders in adolescents and adults.

OBJECTIVES

To determine the physiological values of serum visfatin concentrations, and visfatin mRNA expression in subcutaneous (SAT) and visceral adipose tissue (VAT), and to correlate them with anthropometric/metabolic data in prepubertal healthy boys.

METHODS

The study included 59 healthy boys, age 1-10 years, hospitalized for elective surgery, divided according to age into group I (1-3 years old), group II (3-7 years old) and group III (7-10 years old). Anthropometric and biochemical measurements, and the visfatin serum and mRNA level in SAT and VAT were determined in all patients.

RESULTS

Visfatin mRNA expression was higher in SAT compared with VAT in all three studied groups. Highest visfatin mRNA was found in SAT of group III compared with group II (P = 0.030). VAT visfatin mRNA expression negatively correlates with body weight (P = 0.039), waist circumference (P = 0.027) and morning glucose level (P = 0.007).

CONCLUSION

Lack of changes in serum visfatin level despite the changes in visfatin mRNA expression of adipose tissue suggests paracrine effect of visfatin rather than endocrine. Negative correlation of visfatin VAT mRNA expression with anthropometric parameters indicates important role of VAT visfatin in maturation and in glucose metabolism.

Obesity and Cardiovascular Risk: Variations in Visfatin Gene Can Modify the Obesity Associated Cardiovascular Risk. Results from the Segovia Population Based-Study. Spain

Objectives

Our aim was to investigate if genetic variations in the visfatin gene (SNPs rs7789066/ rs11977021/rs4730153) could modify the cardiovascular-risk (CV-risk) despite the metabolic phenotype (obesity and glucose tolerance). In addition, we investigated the relationship between insulin sensitivity and variations in visfatin gene.

Material and Methods

A population-based study in rural and urban areas of the Province of Segovia, Spain, was carried out in the period of 2001–2003 years. A total of 587 individuals were included, 25.4% subjects were defined as obese (BMI ≥30 Kg/m²).

Results

Plasma visfatin levels were significantly higher in obese subjects with DM2 than in other categories of glucose tolerance. The genotype AA of the rs4730153 SNP was significantly associated with fasting glucose, fasting insulin and HOMA-IR (Homeostasis model assessment-insulin resistance) after adjustment for gender, age, BMI and waist circumference.

The obese individuals carrying the CC genotype of the rs11977021 SNP showed higher circulating levels of fasting proinsulin after adjustment for the same variables.

The genotype AA of the rs4730153 SNP seems to be protective from CV-risk either estimated by Framingham or SCORE charts in general population; and in obese and non-obese individuals. No associations with CV-risk were observed for other studied SNPs (rs11977021/rs7789066).

Conclusions

In summary, this is the first study which concludes that the genotype AA of the rs4730153 SNP appear to protect against CV-risk in obese and non–obese individuals, estimated by Framingham and SCORE charts. Our results confirm that the different polymorphisms in the visfatin gene might be influencing the glucose homeostasis in obese individuals.

Genotypic and phenotypic predictors of inflammation in patients with chronic kidney disease

BACKGROUND

In complex diseases such as chronic kidney disease (CKD), the risk of clinical complications is determined by interactions between phenotypic and genotypic factors. However, clinical epidemiological studies rarely attempt to analyse the combined effect of large numbers of phenotype and genotype features. We have recently shown that the relaxed linear separability (RLS) model of feature selection can address such complex issues. Here, it is applied to identify risk factors for inflammation in CKD.

METHODS

The RLS model was applied in 225 CKD stage 5 patients sampled in conjunction with dialysis initiation. Fifty-seven anthropometric or biochemical measurements and 79 genetic polymorphisms were entered into the model. The model was asked to identify phenotypes and genotypes that, when combined, could separate inflamed from non-inflamed patients. Inflammation was defined as a high-sensitivity C-reactive protein concentration above the median (5 mg/L).

RESULTS

Among the 60 genotypic and phenotypic features predicting inflammation, 31 were genetic. Among the 10 strongest predictors of inflammation, 8 were single nucleotide polymorphisms located in the NAMPT, CIITA, BMP2 and PIK3CB genes, whereas fibrinogen and bone mineral density were the only phenotypic biomarkers.

CONCLUSION

These results indicate a larger involvement of hereditary factors in inflammation than might have been expected and suggest that inclusion of genotype features in risk assessment studies is critical. The RLS model demonstrates that inflammation in CKD is determined by an extensive panel of factors and may prove to be a suitable tool that could enable a much-needed multifactorial approach as opposed to the commonly utilized single-factor analysis.

Obesity-associated sympathetic overactivity in children and adolescents: the role of catecholamine resistance in lipid metabolism

BACKGROUND

Obesity in children and adolescents is characterized by chronic sympathetic overdrive and reduced epinephrine-stimulated lipolysis. This resistance to catecholamines occurs during the dynamic phase of fat accumulation. This review will focus on the relationship between sympathetic-adrenal activity and lipid metabolism, thereby highlighting the role of catecholamine resistance in the development of childhood obesity.

RESULTS AND CONCLUSIONS

Catecholamine resistance causes lipid accumulation in adipose tissue by reducing lipolysis, increasing lipogenesis and impeding free fatty acid (FFA) transportation. Exercise improves catecholamine resistance, as evidenced by attenuated systemic sympathetic activity, reduced circulating catecholamine levels and enhanced β-adrenergic receptor signaling. Insulin resistance is mostly a casual result rather than a cause of childhood obesity. Therefore, catecholamine resistance in childhood obesity may promote insulin signaling in adipose tissue, thereby increasing lipogenesis. This review outlines a series of evidence for the role of catecholamine resistance as an upstream mechanism leading to childhood obesity.

Serum Visfatin and Leptin in Relation to Childhood Adiposity and Body Fat Distribution: The PIAMA Birth Cohort Study

BACKGROUND/AIMS

Visfatin has been suggested as a marker of visceral adiposity. We hypothesized that visfatin, but not leptin, would be specifically associated with visceral adiposity. We investigated the relation of serum visfatin and leptin with measures of adiposity and body fat distribution in children.

METHODS

Serum leptin and visfatin levels were measured in 1,022 12-year-old children participating in the PIAMA birth cohort. BMI, waist, hip and upper arm circumference were available for all children. Multiple linear regression analyses were conducted to study associations between different anthropometric indices and log serum visfatin and leptin levels.

RESULTS

All anthropometric indices showed positive and strong dose-response relationships with serum leptin. Visfatin was increased only in children with a high waist-to-hip ratio. The effect size was small compared to those observed for leptin and the association was present in overweight children (n = 133) but not in normal weight children.

CONCLUSION

Serum leptin levels strongly increased with increasing adiposity, but were not related to a specific type of fat distribution. In contrast, serum visfatin was associated only with high waist-to-hip ratio in overweight children. Based on our study we would currently not recommend visfatin as a marker of visceral adiposity in the general population of children.

The effects of NAMPT haplotypes and metabolic risk factors on circulating visfatin/NAMPT levels in childhood obesity

OBJECTIVE

Polymorphisms in the NAMPT gene, which encodes the adipocytokine visfatin/nicotinamide phosphorybosil transferase (NAMPT), affect the circulating visfatin/NAMPT levels and are associated with obesity and cardiovascular diseases. However, no study has tested the hypothesis that NAMPT haplotypes could affect visfatin/NAMPT levels in case of childhood obesity. We investigated the effects of traditional metabolic risk factors (MRFs) and NAMPT polymorphisms T/C (rs1319501) and A/G (rs3801266) or haplotypes on visfatin/NAMPT levels in obese children and adolescents, and whether NAMPT polymorphisms and/or haplotypes are associated with susceptibility to childhood obesity.

METHODS

We studied 175 control, 99 obese and 82 obese with ⩾ 3 MRFs children and adolescents. Genotypes were determined by a Taqman allele discrimination assay and real-time PCR. The plasma visfatin/NAMPT level was measured using an enzyme immunoassay.

RESULTS

Obese children and adolescents with ⩾ 3 MRFs had higher plasma visfatin/NAMPT levels in comparison with control children and adolescents (P<0.05). Although positive associations were observed between visfatin/NAMPT and body mass index (rs = 0.157; P = 0.034) as well as visfatin/NAMPT and waist circumference (rs = 0.192; P = 0.011), visfatin/NAMPT and high-density lipoprotein cholesterol were inversely associated (rs = -0.162; P = 0.031). No significant differences in genotype, allele or haplotype frequency distributions for the studied polymorphisms were found when the three groups were compared. However, higher plasma visfatin/NAMPT levels were found in control and obese subjects carrying the GG genotype for the A/G (rs3801266) polymorphism (P<0.05) but not in obese children with ⩾ 3 MRFs. Moreover, control subjects carrying the 'T-G' haplotype showed higher plasma visfatin/NAMPT levels. NAMPT genotypes or haplotypes were not associated with childhood obesity.

CONCLUSIONS

Obesity in children with ⩾ 3 MRFs increases plasma visfatin/NAMPT levels, and this marker was associated with body mass index and waist circumference. The A/G polymorphism and NAMPT haplotypes affect plasma visfatin/NAMPT levels in controls but not in obese children with ⩾ 3 MRFs. These results suggest that obesity and MRFs are more influential than genetic polymorphisms in the determination of visfatin/NAMPT levels in obese children. Further research is necessary to explain why the GG genotype is not associated with increased visfatin/NAMPT levels in obese children with ⩾ 3 MRFs.