The relationship between adiponectin, ageing and renal function in a bi-ethnic sample

Effects of an Intervention with Selenium and Coenzyme Q10 on Five Selected Age-Related Biomarkers in Elderly Swedes Low in Selenium: Results That Point to an Anti-Ageing Effect-A Sub-Analysis of a Previous Prospective Double-Blind Placebo-Controlled Randomised Clinical Trial

Background: Ageing is associated with cardiovascular disease (CVD). As no single biomarker reflects the full ageing process, we aimed to investigate five CVD- and age-related markers and the effects of selenium and coenzyme Q10 intervention to elucidate the mechanisms that may influence the course of ageing. Methods: This is a sub-study of a previous prospective double-blind placebo-controlled randomized clinical trial that included 441 subjects low in selenium (mean age 77, 49% women). The active treatment group (n = 220) received 200 µg/day of selenium and 200 mg/day of coenzyme Q10, combined. Blood samples were collected at inclusion and after 48 months for measurements of the intercellular adhesion molecule (ICAM-1), adiponectin, leptin, stem cell factor (SCF) and osteoprotegerin (OPG), using ELISAs. Repeated measures of variance and ANCOVA evaluations were used to compare the two groups. In order to better understand and reduce the complexity of the relationship between the biomarkers and age, factor analyses and structural equation modelling (SEM) were performed, and a structural model is presented. Results: Correlation analyses of biomarker values at inclusion in relation to age, and relevant markers related to inflammation, endothelial dysfunction and fibrosis, demonstrated the biomarkers' association with these pathological processes; however, only ICAM1 and adiponectin were directly correlated with age. SEM analyses showed, however, that the biomarkers ICAM-1, adiponectin, SCF and OPG, but not leptin, all had significant associations with age and formed two independent structural factors, both significantly related to age. While no difference was observed at inclusion, the biomarkers were differently changed in the active treatment and placebo groups (decreasing and increasing levels, respectively) at 48 months (p ≤ 0.02 in all, adjusted), and in the SEM model, they showed an anti-ageing impact. Conclusions: Supplementation with selenium/Q10 influenced the analysed biomarkers in ways indicating an anti-ageing effect, and by applying SEM methodology, the interrelationships between two independent structural factors and age were validated.

The Combination of High Levels of Adiponectin and Insulin Resistance Are Affected by Aging in Non-Obese Old Peoples

BACKGROUND

Adipokine dysregulation is a key feature of insulin resistance and a metabolic syndrome associated with obesity. Low adiponectin levels are associated with higher risks of cardiovascular diseases (CVD). However, high adiponectin levels have also been associated with increased all-cause and cardiovascular mortality in the elderly. This adiponectin paradox has yet to be clarified, which has hindered our understanding of the biological role of adiponectin. Adipokine dysregulation and insulin resistance are also associated with energy-deprivation conditions, such as frailty in old age. The objective of this study was to investigate the association between plasma adiponectin and insulin resistance using the homeostasis model assessment for insulin resistance (HOMA-IR) classified by age. In particular, we sought to determine the factors of the subjects associated with both high adiponectin levels and HOMA-IR (H-adiponectin/H-HOMA) and high adiponectin levels and low HOMA-IR (H-adiponectin/L-HOMA).

METHODS

The eligible subjects in this cross-sectional study were 33,216 individuals who had undergone health checkups at the Physical Checkup Center of Sumitomo Hospital between April 2008 and December 2018. After excluding 26,371 individuals who were under 60 years old, 529 who had been taking medications for diabetes mellitus, and 690 with missing data, the present study included 5,673 (3,467 males, 2,206 females) subjects with no missing data. The relationship between serum adiponectin levels and HOMA-IR was assessed using logistic regression models adjusted by clinically relevant factors.

RESULTS

In the multivariable logistic regression analysis, age and low BMI were shown to positively correlate with the characteristics of H-adiponectin/H-HOMA. In females, systolic blood pressure was also shown to be an associated factor.

CONCLUSION

In conclusion, this study showed that aging or a low BMI may contribute to high adiponectin levels and insulin resistance.

Association of Age and Anemia With Adiponectin Serum Levels in Normal-Weight Japanese Women

BACKGROUND

Adiponectin serum levels are affected by sex, ethnicities, adiposity, age and several pathological conditions such as anemia. The prevalence of hyperadiponectinemia (≥ 20 mg/L) in relation to anemia (hemoglobin < 12 g/dL) was examined in normal-weight Japanese women.

METHODS

Serum adiponectin and blood hemoglobin were measured in 311 young women aged 18 - 24 years (A), 148 of their middle-aged mothers aged 39 - 60 years (B) and 322 community-dwelling women aged ≥ 65 years (C) with a mean body mass index (BMI) of 20.4, 22.0 and 22.4 kg/m2, respectively. Elderly women were subdivided into three age groups: between 65 and 74 years (n = 95, X), between 75 and 84 years (n = 176, Y) and older than 85 years (n = 51, Z).

RESULTS

The prevalence of hyperadiponectinemia (A: 3.9%, B: 3.4%, C: 22.7%, P < 0.001) was low and serum adiponectin (A: 11.5 ± 4.3 mg/L, B: 11.8 ± 4.9 mg/L, C: 15.3 ± 7.8 mg/L, P < 0.001) did not change until middle-aged but increased thereafter in a stepwise fashion (X: 18.9%, Y: 22.7%, Z: 35.3%, P = 0.07 and X: 13.9 ± 6.9 mg/L, Y: 15.1 ± 7.7 mg/L, Z: 18.7 ± 8.6 mg/L, P = 0.001, respectively). There were inverse associations of adiponectin with age (r = -0.201, P < 0.001) and hemoglobin (r = -0.318, P < 0.001) in elderly women but not even in young and middle-aged women combined. Furthermore, anemia was associated with higher prevalence of hyperadiponectinemia (34.8% vs. 20.6%, P = 0.01) and higher serum adiponectin (18.3 ± 9.4 mg/L vs. 14.5 ± 7.1 mg/L, P < 0.001) in elderly women but not in younger and middle-aged women.

CONCLUSIONS

In normal-weight Japanese women, the prevalence of hyperadiponectinemia and serum adiponectin were increased and associated with anemia at 65 years of age and older.

Prevention of kidney cell damage in hyperglycaemia condition by adiponectin

Adiponectin (APN) is an adipocytokine, secreted from adipose tissue and has anti-inflammatory, anti-ageing, and antidiabetic properties. Hyperglycaemia can damage the renal cells, and mammalian target of rapamycin (mTOR), along with Sirtuin 1 (SIRT1), have an important role in kidney cell response to hyperglycaemia. Therefore, understanding the relationship between adiponectin, mTOR, and SIRT1 proteins is beneficial for deciphering the mechanism of adiponectin function. In this study, Human Embryonic Kidney-293 (HEK-293) cells were cultured under normal and high-glucose condition, with and without APN (1, 10, and 100 ng/mL) for 48 hours. mTOR protein expression was evaluated by western blot analysis, and SIRT1 protein was assessed using ELISA method. To evaluate hyperglycaemia-mediated cytotoxicity, cell viability was determined using MTT assay. Data showed that APN in high dose (100 ng/mL) significantly reduced the expression of mTOR and p-mTOR, increased SIRT1 protein, and also improved cell viability compared with the control high glucose (p ≤ 0.05). According to this results, APN can be useful in preventing renal cell damage, by affecting on the expression of mTOR and SIRT1 proteins, as well as increasing the survival of kidney cells in hyperglycaemia conditions. SIGNIFICANCE OF THE STUDY: Adiponectin triggered mTOR/p-mTOR/SIRT1 pathway and decreased cell death in human kidney cells. Our findings provide preliminary experimental data that support further studies on the potential therapeutic role of adiponectin in diabetes and diabetic-induced metabolic complications.

Low BMI is inversely associated with arterial stiffness in Africans

In low socio-economic status communities in South Africa, African men showed a low BMI. Data on the effect of low BMI on cardiovascular function are scant. The present study aimed to assess the associations between low BMI and markers of cardiovascular function such as pulse wave velocity (PWV) and blood pressure in Africans aged 35-65 years, with low socio-economic status. The study population (n 496) was stratified into a low-BMI group with BMI ≤ 20 kg/m² and a normal-BMI group with BMI >20 kg/m² and ≤ 25 kg/m². Blood pressure (Omron HEM-757) and PWV (Complior SP; Artech-Medical) was determined. Africans with low BMI showed an increased arterial stiffness with significantly higher PWV compared with the normal-BMI group (men: P= 0.001; women: P= 0.026), which remained after adjustment. In men with low BMI, PWV correlated negatively with BMI before (r -0.204; P= 0.012) and after (r -0.200; P= 0.020) adjustment. Forward stepwise regression analyses indicated a negative association between PWV and BMI in African men. A J-curve was evident suggesting a detrimental effect of low BMI on cardiovascular function in Africans. A low BMI may contribute to the high prevalence of cardiovascular-related morbidity and mortality within a developing country.

Higher levels of adiponectin in vascular endothelial cells are associated with greater brachial artery flow-mediated dilation in older adults

Adiponectin, an adipocyte-derived protein, exerts anti-atherosclerotic effects on the vascular endothelium. Recently adiponectin protein has been reported in murine vascular endothelial cells, however, whether adiponectin is present in human vascular endothelial cells remains unexplored. We sought to examine 1) adiponectin protein in vascular endothelial cells collected from older adults free of overt cardiovascular disease; 2) the relation between endothelial cell adiponectin and in vivo vascular endothelial function; and 3) the relation between endothelial cell adiponectin, circulating (plasma) adiponectin and related factors. We measured vascular endothelial function (brachial artery flow-mediated dilation using ultrasonography), vascular endothelial cell adiponectin (biopsy coupled with quantitative immunofluorescence) and circulating adiponectin (Mercodia, ELISA) in older, sedentary, non-smoking, men and women (55-79 years). We found that higher endothelial cell adiponectin was related with greater flow-mediated dilation (r = 0.43, P < 0.05) and greater flow-mediated dilation normalized for shear stress (r = 0.56, P < 0.01), but was not related with vascular smooth muscle responsiveness to nitric oxide (r = 0.04, P = 0.9). Vascular endothelial cell adiponectin was not related with circulating adiponectin (r = -0.14, P = 0.6). Endothelial cell and circulating adiponectin were differentially associated with adiposity, metabolic and other factors, but both were inversely associated with renal function (r = 0.44 to 0.62, P ≤ 0.04). In conclusion, higher endothelial cell adiponectin levels are associated with higher vascular endothelial function, independent of circulating adiponectin levels in older adults.

Relationship between serum adiponectin levels and age in healthy subjects and patients with type 2 diabetes

OBJECTIVE

Serum adiponectin levels are affected by gender, body fat mass, several pathological factors or therapeutic interventions and it might be also affected by age. This study aimed to investigate the relationship between serum adiponectin levels and age in several physiological states.

DESIGN, PATIENTS AND MEASUREMENTS

The study was carried out in 21 100 healthy subjects (12 363 men and 8737 women) and 1833 patients with type 2 diabetes (1233 men and 600 women). Physical and demographic characteristics were recorded, and blood samples were collected to measure serum adiponectin levels. Using these data, we determined the relationships between serum adiponectin levels and various parameters, including age.

RESULTS

Serum adiponectin levels increased with increasing age of healthy subjects and in patients with diabetes, in both men and women. Serum adiponectin levels were positively correlated with age in healthy subjects and patients with diabetes, in both men and women. In stepwise multiple regression analysis with serum adiponectin levels as the dependent variable and physiological characteristics as explanatory variables, age was significantly and independently associated with serum adiponectin levels in each of these groups of subjects.

CONCLUSIONS

Serum adiponectin levels are significantly and positively associated with age in healthy subjects and in patients with diabetes. This association is independent of renal function, body fat status, glucose metabolism and lipid profiles.

Anemia and reduced renal function are independent predictors of elevated serum adiponectin in elderly women

AIM

Although higher adiponectin levels predict a low risk of type 2 diabetes, elevated adiponectin levels predict higher mortality in older persons.

METHODS

We examined the associations of adiponectin with anthropometric, metabolic and hematological variables and renal function in 361 community-dwelling elderly women aged 76±8. Renal function was assessed using the estimated glomerular filtration rate (eGFR).

RESULTS

By univariate analysis, hemoglobin (r=-0.307, p<0.001) and creatinine-based eGFR (r=-0.121, p<0.05) were inversely associated with adiponectin. After adjustment for percentage body fat, HDL cholesterol and serum leptin, hemoglobin and creatinine-based eGFR remained independent predictors of adiponectin (standardized β coefficient=-0.248, p<0.0001, and -0.101, p=0.03, respectively). A similar but stronger relationship was observed between adiponectin and cystatin C-based eGFR (standardized β coefficient=-0.180, p=0.02). Elderly women with anemia had higher serum adiponectin than those without anemia (17.7±9.1 vs. 14.1±7.0 µg/mL, p=0.001). Women with creatinine-based eGFR <45 mL/min/1.73 m2 (19.2±10.6 µg/mL) had higher adiponectin than those with eGFR ≥45 -< 60 mL/min/1.73 m(2) (14.4±6.9 µg/mL) and those with eGFR ≥60 mL/min/1.73 m(2) (14.5±7.4 µg/mL, p<0.05).

CONCLUSIONS

We conclude that hemoglobin and eGFR are independently associated with serum adiponectin in community-dwelling elderly women. Anemia and reduced renal function may contribute to elevated adiponectin levels in the elderly and may represent important confounders of the relationship between elevated adiponectin and mortality in this population.

Circulating adiponectin is associated with renal function independent of age and serum lipids in west africans

Adiponectin, a protein secreted by adipose tissue, has been associated with renal dysfunction. However, these observations have not been adequately investigated in large epidemiological studies of healthy individuals in general and in African populations in particular. Hence, we designed this study to evaluate the relationship between adiponectin and renal function in a large group of nondiabetic West Africans. Total adiponectin was measured in 792 participants. MDRD and Cockroft-Gault (CG-) estimated GFR were used as indices of renal function. Linear and logistic regression models were used to determine the relationship between adiponectin and renal function. Adiponectin showed an inverse relationship with eGFR in univariate (Beta_MDRD = −0.18, Beta_CG = −0.26) and multivariate (Beta_MDRD = −0.10, Beta_CG = −0.09) regression analyses. The multivariate models that included age, sex, BMI, hypertension, smoking, HDL-C, LDL-C, triglycerides, and adiponectin explained 30% and 55.6% of the variance in GFR estimated by MDRD and CG methods, respectively. Adiponectin was also a strong predictor of moderate chronic kidney disease (defined as eGFR < 60 mL/min/1.73 m²). We demonstrate that adiponectin is associated with renal function in nondiabetic West Africans. The observed relationship is independent of age and serum lipids. Our findings suggest that adiponectin may have clinical utility as a biomarker of renal function.