Serum Vaspin Levels Are Associated with the Development of Clinically Manifest Arthritis in Autoantibody-Positive Individuals

Objectives

We have previously shown that overweight may increase the risk of developing rheumatoid arthritis (RA) in autoantibody positive individuals. Adipose tissue could contribute to the development of RA by production of various bioactive peptides. Therefore, we examined levels of adipokines in serum and synovial tissue of subjects at risk of RA.

Methods

Fifty-one individuals positive for immunoglobulin M rheumatoid factor (IgM-RF) and/or anti-citrullinated protein antibodies (ACPA), without arthritis, were included in this prospective study. Levels of adiponectin, vaspin, resistin, leptin, chemerin and omentin were determined in baseline fasting serum samples (n = 27). Synovial tissue was obtained by arthroscopy at baseline and we examined the expression of adiponectin, resistin and visfatin by immunohistochemistry.

Results

The development of clinically manifest arthritis after follow-up was associated with baseline serum vaspin levels (HR1.5 (95% CI 1.1 to 2.2); p = 0.020), also after adjustment for overweight (HR1.7 (95% CI 1.1 to 2.5); p = 0.016). This association was not seen for other adipokines. Various serum adipokine levels correlated with BMI (adiponectin r = -0.538, leptin r = 0.664; chemerin r = 0.529) and systemic markers of inflammation such as CRP levels at baseline (adiponectin r = -0.449, omentin r = -0.557, leptin r = 0.635, chemerin r = 0.619, resistin r = 0.520) and ESR (leptin r = 0.512, chemerin r = 0.708), p-value<0.05. Synovial expression of adiponectin, resistin and visfatin was not associated with development of clinically manifest arthritis.

Conclusions

In this exploratory study, serum adipokines were associated with an increased inflammatory state in autoantibody-positive individuals at risk of developing RA. Furthermore, serum vaspin levels may assist in predicting the development of arthritis in these individuals.     

Chemerin as biomarker for insulin sensitivity in males without typical characteristics of metabolic syndrome

To allow early detection and prevention of metabolic disorders, circulating levels of adipokines involved in insulin sensitivity were compared with the hyperinsulinemic-euglycemic clamp. Twenty non-obese normo-glycaemic men (age 32.1 ± 6 years) underwent a clamp procedure. Levels of leptin, adiponectin, resistin, visfatin, omentin and chemerin levels were determined in fasting blood samples. Pearson correlation coefficients between the M-value for insulin sensitivity and fasting levels of chemerin (r = -0.63, P = 0.003) and leptin (r = -0.54, P = 0.013) performed better than conventional surrogate measures of insulin sensitivity (HOMA-IR: r = -0.45, P = 0.048; Quicki: r = 0.36, P = 0.12). However, only the relation between M-value(LBM) and chemerin remained significant when adjusting for BMI and fasting insulin levels (r = -0.559, P = 0.016). In conclusion, fasting levels of chemerin might be used as biomarker to identify insulin resistance in healthy men without typical characteristics of metabolic disorders.     

Evaluation of insulin resistance and plasma levels for visfatin and resistin in obese and non-obese patients with polycystic ovary syndrome

This study was designed to evaluate insulin resistance and plasma levels of visfatin and resistin in obese and non-obese patients with polycystic ovary syndrome (PCOS).A total of 37 premenopausal PCOS patients with (n = 18, mean (SD) age: 27.5 (5.7 years) or without obesity (n = 19, mean (SD) age: 23.7 (3.1) years) and healthy volunteers (n = 18, mean (SD) age:29.8 (4.1) years) were included in this study. Data on clinical characteristics, glycemic parameters and lipid parameters were recorded for each subject as were plasma visfatin and resistin levels. Mean (SD) HOMA-IR values were significantly higher in obese PCOS patients (3.4 (1.7)) compared with non-obese PCOS patients (2.0 (1.2), p<0.01) and controls (1.6 (0.8), p<0.01). No significant difference was noted between study groups in terms of plasma resistin (ng/mL) or visfatin (ng/mL) levels. There was no correlation between serum plasma visfatin (r = 0.127, p = 0.407) and resistin (r = -0.096, p = 0.544) levels and HOMA-IR. In conclusion, our findings revealed increased likelihood of metabolic and dyslipidemic manifestations in obese compared to non-obese PCOS patients, while no significant difference was noted in visfatin and resistin levels among PCOS patients in terms of co-morbid obesity and in comparison to controls.     

Effect of PPAR-delta agonist on the expression of visfatin, adiponectin, and resistin in rat adipose tissue and 3T3-L1 adipocytes

It has been recently reported that activation of PPAR-delta, by specific agonists or genetic manipulation, alleviates dyslipidemia, hyperglycemia, and insulin resistance in animal models of obesity and type 2 diabetes. The purpose of the present study was to determine whether the PPAR-delta agonist has a direct effect on adipokines in visceral adipose tissue of rats and in cultured adipocytes. We examined the expression of visfatin, adiponectin, and resistin mRNA in visceral adipose tissue of Wistar rats fed a high-fat diet and 3T3-L1 adipocytes treated with PPAR-delta agonist (L-165041). Body weight and biochemical measurements were performed. Rats fed a high-fat diet showed a greater increase in body weight than those fed a standard diet (P<0.05), and treatment with L-165041 (10 mg/kg/day) significantly decreased weight gain (P<0.05). The concentration of total cholesterol was lower, and HDL cholesterol was higher in L-165041-treated rats (P<0.05). In the visceral adipose tissue of L-165041-treated rats, visfatin and adiponectin mRNA levels significantly increased compared to those of the untreated rats (P<0.05). However, the expression of resistin decreased in the L-165041-treated rats. Furthermore, in cultured 3T3-L1 adipocytes, the level of visfatin and adiponectin mRNA was up-regulated in response to L-165041 treatment for nine days. By contrast, resistin mRNA levels were down-regulated by L-165041 treatment. The present study provides a novel evidence to suggest that the PPAR-delta agonist has regulatory effects on a variety of adipokines, and these effects might explain some of their metabolic function.     

Resistin and adiponectin levels in subjects with coronary artery disease and type 2 diabetes

BACKGROUND: Resistin and adiponectin are implicated in insulin resistance and atherosclerosis. The objective of this study was to evaluate the association between plasma resistin levels and the presence of coronary artery disease (CAD) or diabetes compared to the controls. In a cross-sectional study, we measured glucose, fasting lipid panel, resistin, adiponectin, insulin, C-reactive protein (CRP) and TNF-alpha in 57 subjects with CAD, 58 subjects with diabetes compared to 45 normal control subjects. Results: Subjects with CAD compared to the control subjects had increased insulin resistance index (39+/-32 vs. 13.45+/-12.73 with p<0.0001), CRP levels (3.8+/-4.03 vs. 2.0+/-2.0 with p<0.05) and decreased levels of adiponectin (12.5+/-4.8 vs. 17.26+/-10.4 with p<0.0003). Subjects with diabetes compared to the controls had had increased insulin resistance index (69+/-19 vs. 13.45+/-12.73 with p<0.001), CRP levels (4.1+/-4.8 vs. 2.0+/-2.0 with p<0.01) and decreased levels of adiponectin (11.58+/-4.8 vs. 17.26+/-10.4 with p<0.001). Compared to the controls, there was no significant difference in the levels of resistin in subjects with CAD (4.92+/-3.2 vs. 4.1+/-2.4) as well as diabetes (4.92+/-3.2 vs. 4.6+/-2.6). Both CRP and resistin levels correlate with TNF-alpha (r=0.557, p<0.000001; r=0.84, p<0.000001). Conclusions: The present study shows decreased plasma adiponectin levels in subjects with diabetes as well as in subjects with CAD is similar to the literature. Plasma levels of resistin in subjects with CAD or diabetes are similar to the controls. However, there was a strong correlation of resistin levels with inflammatory markers. This suggests resistin as an inflammatory marker associated with CAD.     

Changes in adipocyte hormones leptin, resistin, and adiponectin in thyroid dysfunction

Thyroid hormones as well as the recently discovered secretory products of adipose tissue adiponectin and resistin take part in energy metabolism. To study the changes in the adipocyte hormones with changes in the thyroid functional status, we measured adiponectin, resistin, and leptin in 69 subjects with Graves' disease before and 32 patients at follow up after treatment for hyperthyroidism at hypothyroid state. Concentrations of serum adiponectin and resistin were higher in hyperthyroid state than in hypothyroid state (adiponectin: 5.73 +/- 1.1 vs. 3.0 +/- 0.5 ng/ml, P = 0.03) (resistin: 6.378 +/- 0.6 vs. 5.81 +/- 0.57 ng/ml, P < 0.0001). Resistin levels correlate positively with free t4(r = 0.37, P < 0.01), free t3 levels(r = 0.33, P < 0.01) and negatively with TSH(r = -0.22, P < 0.05). Adiponectin levels correlate with free t4(r = 0.33, P < 0.01) and free t3 (r = 0.44, P < 0.01). Though the adiponectin levels did not correlate with leptin or resistin levels, strong positive correlation of both resistin and adiponectin with thyroid hormones is noted. Serum levels of leptin did not change with change in the thyroid functional status (leptin: 53.38 +/- 2.47 vs. 55.10 +/- 2.58 NS). Leptin levels did not correlate with resistin and adiponectin. We conclude that thyroid function has effect on adipocyte hormones adiponectin and resistin but not leptin.     

Plasma and urine levels of resistin and adiponectin in chronic kidney disease

BACKGROUND: Subjects with chronic kidney disease (CKD) have an increased risk of developing coronary atherosclerosis. Adipocyte hormones, resistin and adiponectin are implicated in insulin resistance and atherosclerosis. However, few studies in the literature address the role of adipocyte hormones in CKD. The aim of this study was to compare the levels of resistin, adiponectin and other inflammatory markers in subjects with CKD with those of the control subjects. MATERIALS AND METHODS: In a cross-sectional study, we measured basal metabolic panel, fasting lipid panel and levels of glucose, resistin, adiponectin, insulin, C-reactive protein (CRP) and TNF-alpha in 43 subjects with CKD compared with those of 34 control subjects. We also measured the resistin and adiponectin levels in urine samples (16). RESULTS: Subjects with CKD have increased insulin levels and insulin resistance index (IRI). Compared with controls, subjects with CKD had increased levels of resistin (5.12+/-3.2 vs.7.5+/-5.9; p<0.05), CRP (1.7+/-2.2 vs. 5.97+/-6.0; p<0.0005), and TNF-alpha (3.4+/-2.0 vs. 5.2+/-3.5; p<0.005). Resistin levels correlate with CRP and TNF-alpha, even with BMI as a covariate. Although 60% of subjects with CKD have CAD, e plasma levels of adiponectin were not decreased in subjects with CKD compared with controls (17.02+/-9.8 vs. 16.40+/-9.0 with p value 0.78). Urinary adiponectin levels correlate inversely with GFR (r=-0.4; p<0.05) and plasma adiponectin levels (r=0.9; p<0.0001). CONCLUSIONS: Subjects with CKD had normal levels of plasma adiponectin despite the adverse metabolic environment for CAD. In addition, this study demonstrates the relationship between resistin and TNF-alpha in subjects with CKD and suggests that resistin may play a role in the sub-clinical inflammation associated with CKD, suggesting that adiponectin clearance may be decreased as shown by the inverse correlation of urinary adiponectin with GFR.     

Resistin, visfatin and insulin sensitivity in selected phases of annual training cycle of triathletes

The purpose of the study was to examine the effects of sport training on carbohydrate metabolic indices and adipokines concentrations in young male triathletes (n=10). Athletes performed the incremental running test in two periods of the training cycle: in the transitory and preparatory phases. In both analyzed terms, physical exercise was reflected by a significant increase in lactate (p≤0.01), insulin (p≤0.01), visfatin concentrations (p≤0.01, p<0.05, respectively) and only during transitory phase in glucose (p≤0.01) and resistin concentrations (p<0.05). Significant inter-period differences were noted in the pre-exercise insulin (p≤0.01) and also in pre- and post-exercise visfatin concentrations (p<0.05). Additionally, the differences (Δ) between post- and pre-exercise values of glucose (p<0.05) and visfatin (p≤0.01) significantly decreased in the preparatory phase comparing to the transitory phase. The inverse correlations between pre-exercise concentrations of visfatin and peak oxygen uptake (p<0.05) in the transitory phase and between post- and pre-exercise differences (Δ) of visfatin and lactate concentrations (p<0.05) in the preparatory phase were noted. During preparatory phase, pre-exercise visfatin concentrations inversely correlated with pre-exercise resistin, insulin and glucose levels (p<0.05). In conclusion, systematic training in elite triathletes modulates basal adipokine concentrations only to a small extent, however, influences on these molecules response on the acute exercise.     

Adiponectin: Serum-saliva associations and relations with oral and systemic markers of inflammation

This study addresses gaps in our understanding about the validity and utility of using salivary adiponectin to index serum adiponectin levels. Matched blood and saliva samples were collected on a single occasion from healthy adults (n = 99; age 18–36 years, 53% male). Serum and saliva was assayed for adiponectin and inflammatory cytokines (IL-1β, IL-6, IL-8, TNFα), and saliva was also assayed for markers of blood contamination (transferrin), total protein (salivary flow rate) and matrix metalloproteinase-8 (MMP-8). We examined the extent to which salivary adiponectin was associated with serum adiponectin, and the influence of potential confounders on the serum-saliva correlation, including age, sex, body mass index, and markers of inflammation, oral health, salivary blood contamination, and flow rate. Findings revealed a modest serum-saliva association for adiponectin, and strong positive associations between salivary adiponectin and salivary levels of inflammatory cytokines, MMP-8, transferrin, and total protein. By contrast, salivary adiponectin was not related to serum levels of inflammatory activity. The magnitude of the serum-saliva association was strengthened when controlling for total protein in saliva, blood leakage into oral fluid, salivary inflammatory cytokines, and MMP-8. The pattern of findings extends our understanding of salivary adiponectin and its potential use as an index of circulating adiponectin levels.     

The emerging role of adipokines in osteoarthritis: a narrative review

Osteoarthritis (OA) is a most common multifactorial degenerative joint disease in elderly individuals. OA is affecting severely the quality of life of patients, while the causes of OA are not completely understood. Age, obesity, the female sex, and previous injury are considered as significant risk factors. Recently, increased levels of adipokines which are mainly produced by adipocytes have been detected in patients with osteoarthritis. Moreover, studies on different adipokines all reveal that they have played proinflammatory and catabolic/anabolic roles during the pathophysiology of OA. In the present review, we summarize current data on the effect of the adipose tissue-derived hormones leptin, adiponectin, resistin and visfatin on initiation and progression of OA.     

Can adipokines serum levels be used as biomarkers of hand osteoarthritis?

Purpose: To evaluate serum levels of visfatin, resistin and adiponectin in patients with erosive (E) and non-erosive (NE) osteoarthritis (OA) of the hand (HOA) compared to normal controls (NC).

Methods: 94 outpatients with E HOA and NE HOA and 21 NC were enrolled. The radiological assessment of both hands was performed according to the Kellgren–Lawrence and Kallman score. Patients were divided into two subsets (lone HOA or generalized OA) based on clinically OA involvement of knee and hip. Serum visfatin, resistin and adiponectin levels were determined by ELISA assay.

Results: Visfatin was significantly higher in E HOA patients in comparison to NC and NE HOA group. Resistin showed a significant increase in both E HOA and NE HOA groups versus NC, in particular in generalized OA. No significant differences among groups were found in adiponectin. The Kallman score was more severe in the two subsets of E HOA patients compared to NE HOA.

Conclusions: This study showed increased levels of resistin in erosive and non-erosive HOA, and higher visfatin levels in E HOA in comparison to NE HOA. These data suggest the adipokines possible role in the pathogenesis of HOA and their potential usefulness as biomarkers of the disease.     

Systemic blockade of TNF-α does not improve insulin resistance in humans

The purpose of this study was to determine whether long-term modulation of inflammatory activity by tumor necrosis factor (TNF)-α inhibitors has some influence on insulin resistance (IR). 16 active rheumatoid arthritis (RA) patients without CV risk factors treated with anti-TNF-α agents were included in this study. RA activity by disease activity score 28, IR by HOMA2-IR, body composition by impedance analysis, physical activity by accelerometry, abdominal fat distribution by magnetic resonance imaging, and serum level of key adipokines by ELISA were measured at baseline and during a 1-year follow-up period. Patient body mass index increased significantly (26.94 ± 3.88 vs. 28.06 ± 4.57 kg/m2, p=0.02) after 1 year of treatment. Body composition, in terms of fat and fat-free mass, remained unchanged except for a significant elevation in body cell mass (25.50 ± 4.60 vs. 26.60 ± 3.17 kg, p=0.02). Basal levels of IR in the RA patients included in this study were significantly higher than healthy controls (1.6 ± 0.8 vs. 1.11 ± 0.56, p=0.011) but did not change during the follow-up. Nor did basal concentrations of adiponectin, visfatin, leptin, ghrelin, resistin, and apelin in response to anti-TNF-α treatment; only retinol-binding protein 4, showed a significant increase (51.7 ± 32.7 vs. 64.9 ± 28.4 μg/ml, p=0.03) at the end of the study. IR, adiposity distribution, and serum levels of most adipokines are not significantly affected by long-term inhibition of TNF-α in RA patients. Our data suggest that although systemic blockade of TNF-α exerts an anticachectic effect in RA patients, it does not seem to play a major role in IR.     

Relationship Between Serum Lithium, Salivary Lithium, and Urinary Lithium in Patients on Lithium Therapy

Lithium carbonate is used in the treatment of both psychiatric and nonpsychiatric disorders. The aim of this study was to explore the relationship between serum lithium, salivary lithium, and urinary lithium. Blood, saliva, and urine samples were collected from 50 patients, and estimation of serum, salivary, and urine lithium was done using an atomic absorption spectrophotometer. Mean serum lithium was 0.75 ± 0.25 mEq/L, mean salivary lithium was 1.91 ± 0.80 mEq/L, and mean urine lithium was 7.16 ± 4.84 mEq/L. A significant direct correlation was found between serum lithium and salivary lithium (r = 0.695, p < 0.001). This correlation was higher in females (r = 0.770, p < 0.001) when compared to males (r = 0.665, p < 0.001). Even though a significant correlation was found between serum and salivary lithium levels, more studies are needed in this domain to establish salivary therapeutic monitoring as a feasible option for patients on lithium carbonate therapy.     

Impact of Treatment with Metformin on Adipocytokines in Patients with Polycystic Ovary Syndrome: A Meta-Analysis

Background

Metformin is effective for the treatment of polycystic ovary syndrome, but conflicting results regarding its effect on adipocytokine levels (adiponectin, resistin, visfatin, and leptin) in patients with polycystic ovary syndrome receiving metformin treatment have been reported. To provide high-quality evidence about the effect of metformin treatment on adipocytokines in patients with polycystic ovary syndrome, relevant studies that assessed the levels of adipocytokines (adiponectin, resistin, visfatin, and leptin) in patients with polycystic ovary syndrome receiving treatment with metformin administration were reviewed and analyzed.

Methods

A literature search was conducted in the SCI, PUBMED, EMBASE, and Elsevier databases, and personal contact was made with the authors. Standard mean differences and 95% confidence intervals were calculated and combined appropriately. To ensure synthesis of the best available evidence, sensitivity analyses were performed.

Results

A total of 34 data sets were included in 4 different outcomes, involving 744 women with polycystic ovary syndrome and adipocytokine levels measured both before and after metformin administration. Metformin treatment was associated with significantly elevated serum adiponectin concentrations (standard mean differences [95% confidence interval], −0.43 [−0.75 to −0.11]) and decreased serum leptin concentrations (0.65 [0.26 to 1.04]), whereas no significant difference in resistin level (−0.01 [−0.49 to 0.45]) or visfatin level (−0.04 [−1.55 to 1.46]) was found.

Conclusions

Metformin administration was associated with increased serum adiponectin concentrations and decreased serum leptin levels. Further study is needed to elucidate whether this apparent effect decreases the incidence of type 2 diabetes and other metabolic diseases in patients with polycystic ovary syndrome later in life.     

Relationship of serum adiponectin and resistin levels with the severity of liver fibrosis in patients with chronic hepatitis B

BackgroundRecent research has closely linked adipocytokines to liver inflammation and fibrosis progression in patients with non-alcoholic liver disease. This study aimed to determine the relationship of serum adiponectin and resistin levels with the severity of liver fibrosis in patients with chronic hepatitis B (CHB), depending on the duration of antiviral therapy.MethodsThe cross-sectional study included 75 patients with CHB divided into two groups: the T1 group (undergoing antiviral therapy for up to 2 years) and the T2 group (undergoing antiviral therapy over 2 years). The control group consisted of 40 healthy people. Serum concentrations of adiponectin and resistin were estimated with the ELISA method, while the degree of liver fibrosis was determined using FIB-4 and APRI score.ResultsThere were no statistically significant differences in the mean serum adiponectin levels in relation to the duration of antiviral therapy. Higher values of serum resistin concentration were confirmed in patients of the T1 group compared to healthy controls (p=0.001) and to the T2 group (p=0.031). The mean level of serum resistin concentration was significantly higher in the group of patients with a higher FIB-4 score (9.12±3.39 vs 5.58±3.36 ng/mL, p=0.001) and higher APRI score (17.45±3.96 ng/mL vs 4.82±1.11 ng/mL, p=0.001). A positive correlation was found between serum resistin levels and the degree of liver fibrosis (p<0.001). There was no significant difference between mean serum adiponectin levels according to the values of FIB-4 and APRI scores.ConclusionsProgression of liver fibrosis estimated by FIB4 and APRI scores as well as the length of antiviral treatment had a significant effect on serum resistin values in CHB patients on antiviral therapy.     

Apelin, vaspin, visfatin and adiponectin in large for gestational age infants with insulin resistance

Objective

To investigate the relation of circulating four adipokines (apelin, vaspin, visfatin, adiponectin) with markers of insulin sensitivity in large for gestational age (LGA) infants.

Patients and methods

Forty LGA infants (20 LGA born from diabetic mothers and 20 LGA born from non-diabetic mothers) and 34 appropriate for gestational age (AGA) infants were recruited. Hyperinsulinism and insulin resistance was evaluated using the homeostasis model assessment (HOMA-IR), fasting glucose-to-insulin ratio (FGIR), quantitative insulin-sensitivity check index (QUICK-I) from fasting samples. Plasma adiponectin and vaspin levels were determined by radioimmunoassay. Determination of visfatin and apelin levels was performed by enzyme immunoassay.

Results

HOMA-IR, apelin and visfatin levels (p < 0.001, p < 0.001, p < 0.001, respectively) were significantly elevated and adiponectin levels, FGIR and QUICK-I values. (p < 0.001, p < 0.001, p < 0.05, respectively) were significantly lower in the LGA group. Vaspin levels were higher in the LGA group than AGA neonates without a significance. The LGA infants with diabetic mother had significantly higher visfatin, apelin, HOMA-IR values, fasting insulin levels and significantly lower adiponectin, FGIR, QUICK-I values. Apelin and visfatin were correlated positively, and adiponectin was correlated negatively with birthweight, HOMA-IR values and fasting insulin levels.

Conclusion

Based on the findings of this study, it is too difficult to explain relation between birthweight and these adipocytokines, but findings of high insulin, HOMA-IR, visfatin, apelin and low adiponectin levels in the LGA neonates showed that these adipocytokines can be used as a good predictor for metabolic syndrome.     

Metabolic Hormones,Apolipoproteins, Adipokines,and Cytokines in the Alveolar Lining Fluid of Healthy Adults: Compartmentalization and Physiological Correlates

Objectives

Our current understanding of hormone regulation in lung parenchyma is quite limited. We aimed to quantify a diverse array of biologically relevant protein mediators in alveolar lining fluid (ALF), compared to serum concentrations, and explore factors associated with protein compartmentalization on either side of the air-blood barrier.

Research Design and Methods

Participants were 24 healthy adult non-smoker volunteers without respiratory symptoms or significant medical conditions, with normal lung exams and office spirometry. Cell-free bronchoalveolar lavage fluid and serum were analyzed for 24 proteins (including enteric and metabolic hormones, apolipoproteins, adipokines, and cytokines) using a highly sensitive multiplex ELISA. Measurements were normalized to ALF concentrations. The ALF:serum concentration ratios were examined in relation to measures of protein size, hydrophobicity, charge, and to participant clinical and spirometric values.

Results

ALF measurements from 24 individuals detected 19 proteins, including adiponectin, adipsin, apoA-I, apoA-II, apoB, apoC-II, apoC-III, apoE, C-reactive protein, ghrelin, glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1), glucagon, insulin, leptin, monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, resistin, and visfatin. C-peptide and serpin E1 were not detected in ALF for any individual, and IL-6, IL-10, and TNF-alpha were not detected in either ALF or serum for any individual. In general, ALF levels were similar or lower in concentration for most proteins compared to serum. However, ghrelin, resistin, insulin, visfatin and GLP-1 had ALF concentrations significantly higher compared to serum. Importantly, elevated ALF:serum ratios of ghrelin, visfatin and resistin correlated with protein net charge and isoelectric point, but not with molecular weight or hydrophobicity.

Conclusions

Biologically relevant enteric and metabolic hormones, apolipoproteins, adipokines, and cytokines can be detected in the ALF of healthy individuals. For the proteins measured, charge may influence trafficking and compartmentalization to the alveolar airspace more than molecular weight or hydrophobicity. These data may have implications for homeostasis and drug delivery to the lung.     

Influence of bone mineral density in circulating adipokines among postmenopausal Arab women

Osteoporosis and osteopenia has a significant link with substantial fracture risk. Epidemiological data revealed a protective role of adipose tissue on bone biology in postmenopausal osteoporosis. The current study assessed the associations between select adipokines and bone mineral density (BMD) in postmenopausal women. A total of 175 Saudi postmenopausal women were selected and categorized based on their BMD (normal & low-BMD). Circulating levels of select adipokines (adiponectin, resistin, leptin, and adipsin), insulin, 25(OH)D and RANKl were determined using commercially available assay kits. BMD was measured by dual-energy X-ray absorptiometry (DXA). Overall and among low-BMD subjects, adiponectin consistently showed a significant inverse association with BMD (overall −0.34, p < 0.01; low BMD group −0.34, p < 0.01). In multiple regression, adiponectin (−0.29 ± 0.06, p < 0.00) and resistin (−0.08 ± 0.04, p < 0.05) were inversely significant with BMD overall, but after stratification the significance was lost for resistin (−0.05 ± 0.04, p < 0.224) whereas adiponectin remained (−0.22 ± 0.07, p < 0.02) in low-BMD subjects. Adipsin, leptin and lipocalin-2 showed no significant associations. Findings of the present study revealed that only adiponectin showed a significantly strong inverse association with low BMD, suggesting that insulin sensitivity may influence bone health in Arab postmenopausal women.     

Adipokine expression is associated with adipocyte volume in baboons

Baboons show significant variation in body weight and composition, coupled with insulin resistance and phenotypes associated with the metabolic syndrome. An omental adipose tissue biopsy and a fasting blood sample were collected from 40 unrelated adult baboons from the colony at Southwest Foundation for Biomedical Research in San Antonio, TX. Serum was separated for analyses of circulating levels of glucose, insulin, adiponectin, resistin, interleukin 6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1 or CCL-2). Adipose tissue biopsies were analyzed for cell volume and number. Total RNA was isolated from adipose tissue and adiponectin, resistin, delta-resistin, MCP-1 and IL-6 mRNA abundance were measured using real time, quantitative RT-PCR. Partial correlation coefficients were calculated among adipokine expression, fat tissue cell volume, and circulating levels of proteins. Cell volume was significantly correlated with expression of MCP-1 (r=0.44, p<0.05) and IL-6 mRNA (r=0.47, p<0.01). A step wise regression analysis was conducted with adipose tissue cell volume as dependent variable. The model identified IL-6 mRNA levels in adipose tissue as the only predictor. These observations support the role of IL-6 as a possible paracrine regulator in adipose tissue.