Effect of exercise training on A-FABP, lipocalin-2 and RBP4 levels in obese women

Periodontal therapy decreases serum levels of adipocyte fatty acid-binding protein in systemically healthy subjects: a pilot clinical trial

BACKGROUND AND OBJECTIVE

Adipocyte fatty acid-binding protein (A-FABP) is expressed in adipocytes, macrophages and microvascular endothelial cells, and it plays a central role in inflammation, atherosclerosis and metabolic responses. This pilot study investigated the effect of nonsurgical periodontal therapy on the serum levels of A-FABP in subjects with chronic periodontitis.

MATERIAL AND METHODS

A pilot clinical trial was conducted in 24 otherwise healthy Chinese subjects with moderate to severe chronic periodontitis. The treatment group (n = 12) received nonsurgical periodontal therapy immediately, whereas in the control group (n = 12) the treatment was delayed for 3 months. The serum levels of A-FABP were measured by ELISAs. Other inflammatory and endothelial biomarkers and periodontal conditions were evaluated at baseline and at the 3-month follow-up appointment.

RESULTS

A-FABP levels decreased significantly in the treatment group compared with the control group (treatment effect: -1.7 ng/mL; 95% confidence interval: -2.8 to -0.6; p = 0.003). The treatment also significantly improved periodontal conditions but had no significant effect on other biomarkers. In the multivariable regression model, the change in the percentage of sites with detectable plaque was significantly associated with the change in the level of A-FABP (beta: 0.04, 95% confidence interval: 0.01-0.06, p = 0.004).

CONCLUSION

Within the limitations of this pilot study, the current findings suggest that treatment of periodontitis may significantly decrease the serum levels of A-FABP. Further longitudinal study with a large sample size is warranted to confirm this finding and elaborate the relevant clinical implications.

An overview of the contribution of fatness and fitness factors, and the role of exercise, in the formation of health status for individuals who are overweight

Over the last half century there has been an epidemic of diminished health status induced by what seems as a concurrent rise in a population of individuals that are overfat. During the past few decades, the use of exercise has become a staple in the prevention and treatment options for the retarding the development of health issues pertaining to individuals who are overweight, overfatness or experience obesity. However, there are few studies and reviews look at the global issues surrounding the metabolic and hormone consequences of overfatness and the interaction of exercise with adiposity in humans developing the health status for the individual. This review offers an insight into our current understanding of health issues pertaining to metabolic and hormonal disruption related to overfatness and the treatment effect that exercise, especially resistance exercise, can have on impacting the health status, and overall well-being, for individuals who are overfat, regardless of body compositional changes leading toward a lessening of diseased state, and eventually a return to a normal health status for the individual.

Lipocalin-2: Response to a Progressive Treadmill Protocol in Obese and Normal-weight Men

Purpose

Lipocalin-2 (Lcn2), a newer adipocyte-secreted acute phase protein, was recently reported to be correlated with potential effects on obesity and inflammation. The reaction of this protein to progressive exercise has not been evaluated yet. This study was designed to compare the serum Lcn2 and high-sensitivity C-reactive protein (hs-CRP) levels after participating in an acute bout of treadmill protocol in obese and normal-weight men.

Methods

Nine obese (aged: 43.2±4.6 yrs and body mass index (BMI): 31.4±1.6 kg/m²) and 9 normal-weight (aged: 42.9±4.4 yrs and BMI: 23.03±1.7 kg/m²; mean ± SD) sedentary men selected randomly from volunteers performed a single bout of exercise according to the treadmill Bruce protocol.

Results

Before the exercise, Lcn2 level was higher in obese than normal-weight individuals (P<0.05). A significant increase in Lcn2, hs-CRP, white blood cells (WBC) and insulin resistance index was observed after the exercise in both groups (P<0.05). The level of Lcn2, hs-CRP and WBC increase was more significant in obese individuals than normal-weight subjects after the exercise (P<0.05).

Conclusions

It seems that the levels of Lcn2 and other inflammatory markers elevated in obese and normal-weight men after participating in an exhaustive progressive exercise. These changes in obese men were considerable.

The multifaceted roles of neutrophil gelatinase associated lipocalin (NGAL) in inflammation and cancer

Neutrophil gelatinase associated lipocalin (NGAL), also known as oncogene 24p3, uterocalin, siderocalin or lipocalin 2, is a 24kDa secreted glycoprotein originally purified from a culture of mouse kidney cells infected with simian virus 40 (SV-40). Subsequent investigations have revealed that it is a member of the lipocalin family of proteins that transport small, hydrophobic ligands. Since then, NGAL expression has been reported in several normal tissues where it serves to provide protection against bacterial infection and modulate oxidative stress. Its expression is also dysregulated in several benign and malignant diseases. Its small size, secreted nature and relative stability have led to it being investigated as a diagnostic and prognostic biomarker in numerous diseases including inflammation and cancer. Functional studies, conducted primarily on lipocalin 2 (Lcn2), the mouse homologue of human NGAL have revealed that Lcn2 has a strong affinity for iron complexed to both bacterial siderophores (iron-binding proteins) and certain human proteins like norepinephrine. By sequestering iron-laden siderophores, Lcn2 deprives bacteria of a vital nutrient and thus inhibits their growth (bacteriostatic effect). In malignant cells, its proposed functions range from inhibiting apoptosis (in thyroid cancer cells), invasion and angiogenesis (in pancreatic cancer) to increasing proliferation and metastasis (in breast and colon cancer). Ectopic expression of Lcn2 also promotes BCR-ABL induced chronic myelogenous leukemia in murine models. By transporting iron into and out of the cell, NGAL also regulates iron responsive genes. Further, it stabilizes the proteolytic enzyme matrix metalloprotease-9 (MMP-9) by forming a complex with it, and thereby prevents its autodegradation. The factors regulating NGAL expression are numerous and range from pro-inflammatory cytokines like interleukins, tumor necrosis factor-α and interferons to vitamins like retinoic acid. The purpose of this review article is to examine the expression, structure, regulation and biological role of NGAL and critically assess its potential as a novel diagnostic and prognostic marker in both benign and malignant human diseases.

The association between the preoperative serum levels of lipocalin-2 and matrix metalloproteinase-9 (MMP-9) and prognosis of breast cancer

Background

Although a number of experimental studies have suggested the role of lipocalin-2 (LCN2) and matrix metalloproteinase-9 (MMP-9) in breast cancer progression, limited numbers of epidemiological studies have examined the relationship between the levels of lipocalin-2 and MMP-9 and breast cancer survival.

Methods

Preoperative serum levels of lipocalin-2 and MMP-9 were measured in 303 breast cancer patients and 74 healthy controls recruited between 2004 and 2007. We examined the association between lipocalin-2 and MMP-9 levels and disease-free survival (DFS) using Cox proportional hazard regression model.

Results

The serum levels of lipocalin-2 and MMP-9 were not significantly different between patients and controls (P > 0.05). Elevated lipocalin-2 and MMP-9 levels were associated with reduced DFS of breast cancer ( P_trend = 0.029 and P_trend = 0.063, respectively). When lipocalin-2 and MMP-9 levels were categorized based on the combined risk score, patients with higher levels of both lipocalin-2 and MMP-9 exhibited poor DFS compared to patients with lower levels (P_trend = 0.004). Furthermore, these effects were profound in patients with BMI less than 25 kg/m² (adjusted hazard ratio (aHR), 3.17; 95% confidence intervals (CI), 1.66-6.06, P_trend < 0.001) or lymph-node negative breast cancer (aHR, 5.36; 95% CI, 2.18-13.2, P_trend < 0.001).

Conclusions

Our study suggests that the elevated levels of lipocalin-2 and MMP-9 are associated with reduced breast cancer survival, particularly in patients with lower BMI and lymph-node negative breast cancers.

Physical Activity and Obesity Research in the Asia-Pacific

Obesity is a global health concern and has a great impact on countries in the Asia-Pacific region. Physical inactivity is a major risk factor for obesity, but physical activity levels are declining in much of this region. Increasing physical activity is a priority in many countries. Considerable research has been conducted on physical activity related to obesity in Western countries, but populations in the Asia-Pacific region differ in physical, psychological, social, and cultural ways that warrant local and regional research. The authors reviewed research conducted in the Asia-Pacific region that examined either the impact of physical activity interventions on obesity-related outcomes or the effect of behavior-change interventions on physical activity participation. The number of studies found was limited, and their samples and methods varied too much to draw conclusions. The authors recommend further research in the Asia-Pacific region using systematic protocols to permit sound conclusions to be drawn and promote informed action at local levels.

Small lipid-binding proteins in regulating endothelial and vascular functions: focusing on adipocyte fatty acid binding protein and lipocalin-2

Dysregulated production of adipokines from adipose tissue plays a critical role in the development of obesity-associated cardiovascular abnormalities. A group of adipokines, including adipocyte fatty acid binding protein (A-FABP) and lipocalin-2, possess specific lipid-binding activity and are up-regulated in obese human subjects and animal models. They act as lipid chaperones to promote lipotoxicity in endothelial cells and cause endothelial dysfunction under obese conditions. However, different small lipid-binding proteins modulate the development of vascular complications in distinctive manners, which are partly attributed to their specialized structural features and functionalities. By focusing on A-FABP and lipocalin-2, this review summarizes recent advances demonstrating the causative roles of these newly identified adipose tissue-derived lipid chaperones in obesity-related endothelial dysfunction and cardiovascular complications. The specific lipid-signalling mechanisms mediated by these two proteins are highlighted to support their specialized functions. In summary, A-FABP and lipocalin-2 represent potential therapeutic targets to design drugs for preventing vascular diseases associated with obesity.

LINKED ARTICLES

This article is part of a themed section on Fat and Vascular Responsiveness. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-3.

Effects of exercise training on circulating retinol-binding protein 4 and cardiovascular disease risk factors in obese men

INTRODUCTION

The purpose of this study was to investigate the effects of 12-week exercise training on circulating retinol-binding protein 4 (RBP4) concentration and cardiovascular disease (CVD) risk factors in obese men.

METHODS

29 obese men (age 48 ± 2 years; BMI 29.6 ± 0.7 kg/m(2)) participated in a 12-week exercise program (50-70% maximal heart rates; 3 times/week) without calorie restriction. Anthropometric parameters, CVD risk factors (total cholesterol, high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol, triglycerides (TG), and quantitative insulin sensitivity check index), and circulating RBP4 and adipokine (adiponectin, leptin, and interleukin-6 (IL-6)) concentrations were measured.

RESULTS

Exercise training significantly improved in absolute peak oxygen consumption (p < 0.05), and CVD risk factors (p < 0.05), with the exception of HDLC. There was a significant decrease in circulating RBP4, leptin, and IL-6 concentrations (p < 0.05). Stepwise regression analysis revealed that changes in RBP4 concentration were independently related to the changes in TG concentration (β = 0.46, p < 0.05).

CONCLUSION

These results demonstrate that exercise training without calorie restriction improves several CVD risk factors and circulating RBP4 and adipokine concentrations. Moreover, the change in circulating RBP4 may be more associated with the improvements in TG concentration in obese men.

Circulating lipocalin 2 is associated with body fat distribution at baseline but is not an independent predictor of insulin resistance: the prospective Cyprus Metabolism Study

OBJECTIVE

Lipocalin 2 (LCN2 or NGAL), a protein derived from neutrophils, macrophages, adipocytes, and other cells, has been proposed to be a link between obesity and insulin resistance (IR), but animal and cross-sectional human studies have revealed conflicting results. We studied the association of serum lipocalin 2 with anthropometric, metabolic, and cardiovascular risk markers in young healthy men cross-sectionally and, for the first time, prospectively after 2 years of follow-up, with and without adjustment for potential confounders including serum creatinine.

DESIGN

Two hundred and seventy-two participants were randomly selected from the Cyprus Metabolism Study (1056 men, 18 years), of whom 93 subjects participated in the follow-up study 2 years after baseline assessment. Associations were also explored between total and free leptin levels (to serve as positive controls) and anthropometric metabolic variables.

RESULTS

In the cross-sectional study, lipocalin 2 levels were marginally correlated in the unadjusted model with central fat distribution but not with body weight or total body fat mass. After adjusting for age, smoking, activity, body mass index, fat percentage, waist-to-hip ratio, and serum creatinine, no correlation was found with any cardiovascular risk factor. There was no correlation with the homeostasis model assessment of IR (HOMA-IR) at baseline. In the prospective analyses, baseline levels of lipocalin 2 were not predictive of any variables in unadjusted or adjusted models. As expected, total and free leptin were associated with anthropometric and metabolic variables both cross-sectionally and prospectively.

CONCLUSIONS

We demonstrate that lipocalin 2 is not an independent predictor of metabolic and cardiovascular risk factors in young men cross-sectionally or prospectively.

Dietary exercise as a novel strategy for the prevention and treatment of metabolic syndrome: effects on skeletal muscle function

A sedentary lifestyle can cause metabolic syndrome to develop. Metabolic syndrome is associated with metabolic function in the skeletal muscle, a major consumer of nutrients. Dietary exercise, along with an adequate diet, is reported to be one of the major preventive therapies for metabolic syndrome; exercise improves the metabolic capacity of muscles and prevents the loss of muscle mass. Epidemiological studies have shown that physical activity reduces the risk of various common diseases such as cardiovascular disease, diabetes, and cancer; it also helps in reducing visceral adipose tissue. In addition, laboratory studies have demonstrated the mechanisms underlying the benefits of single-bout and regular exercise. Exercise regulates the expression/activity of proteins associated with metabolic and anabolic signaling in muscle, leading to a change in phenotype. The extent of these changes depends on the intensity, the duration, and the frequency of the exercise. The effect of exercise is also partly due to a decrease in inflammation, which has been shown to be closely related to the development of various diseases. Furthermore, it has been suggested that several phytochemicals contained in natural foods can improve nutrient metabolism and prevent protein degradation in the muscle.

Fasting serum fatty acid-binding protein 4 level positively correlates with metabolic syndrome in hemodialysis patients

BACKGROUND AND AIMS

Serum fatty acid-binding protein 4 (FABP4) level increases in patients with metabolic syndrome (MetS). The interrelationships between fasting FABP4 levels and MetS have not been analyzed in hemodialysis (HD) patients.

METHODS

Fasting blood samples were obtained from 101 chronic HD patients. MetS was defined according to the diagnostic criteria of the International Diabetes Federation.

RESULTS

In total, 48 HD patients (47.5%) had MetS. Fasting FABP4 levels positively correlated with MetS (p = 0.022). Univariate linear regression analysis showed that the pre-HD body weight (p <0.001), waist circumference (p = 0.003), body mass index (p = 0.003), total cholesterol (TCH) (p <0.001), triglyceride (TG) (p <0.001), creatinine (p = 0.042), insulin level (p = 0.014), and homeostasis model assessment of insulin resistance (HOMA-IR; p = 0.015) were positively correlated with serum FABP4 levels, whereas high-density lipoprotein-cholesterol (HDL-C) (p = 0.049) and adiponectin level (p = 0.004) were negatively correlated with fasting serum FABP4 levels in HD patients.

CONCLUSIONS

MetS was positively correlated with fasting FABP4 levels in our chronic HD patients. TG, TCH, and waist circumference were independent predictors of serum FABP4 levels in HD patients.

[Association between chicken A-FABP gene polymorphisms and growth and body composition traits]

This experiment was designed to study the effects of polymorphism of A-FABP gene on growth and body composition traits in chicken. The 10th generation broiler population, derived from the Northeast Agricultural University broiler lines divergently selected for abdominal fat content (NEAUHLF) was used. Polymorphism among individuals was detected by DNA sequencing, PCR-RFLP, PCR-LP, and DHPLC. Linkage disequilibrium analysis for eight SNPs was performed, and five htSNPs were selected to construct haplotypes. The association analysis between the individual SNPs and haplotypes and growth and body composition traits were investigated, respectively. The results showed that there were consistently significant effects on muscle stomach weight (MSW) and percentage of muscle stomach (MSW/BW) (Pamp;0.05) in the seven SNPs (except for SNP 5) and haplotypes, but no significant effect on any other trait (P>0.05). Due to no evidence on effects of A-FABP for digestion system in other species, future experiments need to be developed to confirm whether A-FABP could be a major gene of MSW and MSW/BW traits in broiler chicken.

Serum adipocyte fatty acid-binding protein, retinol-binding protein 4, and adiponectin concentrations in relation to the development of the metabolic syndrome in Korean boys: a 3-y prospective cohort study

BACKGROUND

Adipocyte fatty acid-binding protein (A-FABP), retinol-binding protein 4 (RBP4), and adiponectin have been associated with insulin resistance and the metabolic syndrome in adults.

OBJECTIVE

We evaluated the association of A-FABP, RBP4, and adiponectin with the metabolic syndrome in Korean boys.

DESIGN

In this prospective cohort study, 159 boys participated in a school-based health examination and were followed up after 3 y. The metabolic syndrome in children was defined by using the pediatric adaptation of the National Cholesterol Education Program criteria.

RESULTS

Compared with normal-weight participants, overweight children had significantly higher A-FABP (23.6 ± 8.2 compared with 12.8 ± 5.1 μg/L, P < 0.001) and RBP4 (69.3 ± 17.1 compared with 59.7 ± 15.3 μg/mL, P = 0.001) concentrations and significantly lower adiponectin concentrations (11.5 ± 5.4 compared with 18.1 ± 8.4 μg/mL, P < 0.001). Baseline A-FABP concentrations were significantly higher in children who developed the metabolic syndrome than in those who did not, whereas adiponectin concentrations were significantly lower. Baseline RBP4 concentrations were not significantly different between the 2 groups. Multiple logistic regression analysis showed that only A-FABP was an independent predictor of the development of the metabolic syndrome after adjustment for Tanner stage, insulin resistance, body mass index, sleep duration, and physical activity (odds ratio: 17.3; 95% CI: 1.25, 239.76; highest compared with lowest tertile), whereas the significant association between adiponectin and the metabolic syndrome observed by using bivariate analysis reflects, in part, an underlying association with obesity.

CONCLUSION

A-FABP predicts the development of the metabolic syndrome independently of pubertal status, adiposity, and insulin resistance in Korean boys.

Circulating adipocyte fatty acid-binding protein, juvenile obesity, and metabolic syndrome

Adipocyte fatty acid-binding protein (A-FABP) links obesity and metabolic syndrome (MetS) and might be targeted in future therapies. Its utility as a MetS biomarker has been suggested in adults but has not been examined in children/adolescents. Our objectives were to identify metabolic parameters associated with A-FABP elevation in children and adolescents and to evaluate the effect of obesity intervention and A-FABP diagnostic utility. A-FABP and anthropometric, metabolic, and inflammatory indices were measured in 31 lean and 114 overweight/obese children and adolescents and reassessed after obesity intervention (1 year; diet and enhanced physical activity, with or without metformin). A-FABP was significantly higher in overweight/ obese than lean individuals, where it correlated with insulin, waist circumference (WC), and 2-h glucose independent of body mass index (BMI), age, gender, and developmental stage. The pattern of A-FABP associations differed between sexes. As a MetS indicator, A-FABP had 68% accuracy. The weight reduction program was effective in reducing A-FABP, BMI%, WC, triglycerides, and cholesterol. In conclusion, elevation in A-FABP is associated with MetS components independent of BMI status and can be reduced by diet and enhanced physical activity. A-FABP as a single MetS biomarker has a moderate accuracy.