Adiponectin is not associated with renal function decline in community-dwelling elderly adults

Genetically predicted adiponectin causally reduces the risk of chronic kidney disease, a bilateral and multivariable mendelian randomization study

Background: It is not clarified whether the elevation of adiponectin is the results of kidney damage, or the cause of kidney function injury. To explore the causal association of adiponectin on estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD), this study was performed.

Materials and methods: The genetic association of adiponectin were retrieved from one genome-wide association studies with 39,883 participants. The summary-level statistics regarding the eGFR (133,413 participants) and CKD (12,385 CKD cases and 104,780 controls) were retrieved from the CKDGen consortium in the European ancestry. Single-variable Mendelian randomization (MR), bilateral and multivariable MR analyses were used to verify the causal association between adiponectin, eGFR, and CKD.

Results: Genetically predicted adiponectin reduces the risk of CKD (OR = 0.71, 95% CI = 0.57–0.89, p = 0.002) and increases the eGFR (β = 0.014, 95% CI = 0.001–0.026, p = 0.034) by the inverse variance weighting (IVW) estimator. These findings remain consistent in the sensitivity analyses. No heterogeneity and pleiotropy were detected in this study (P for MR-Egger 0.617, P for global test > 0.05, and P for Cochran’s Q statistics = 0.617). The bilateral MR identified no causal association of CKD on adiponectin (OR = 1.01, 95% CI = 0.96–1.07, p = 0.658), nor did it support the association of eGFR on adiponectin (OR = 0.86, 95% CI = 0.68–1.09, p = 0.207) by the IVW estimator. All the sensitivity analyses reported similar findings (p > 0.05). Additionally, after adjusting for cigarette consumption, alcohol consumption, body mass index, low density lipoprotein, and total cholesterol, the ORs for CKD are 0.70 (95% CI = 0.55–0.90, p = 0.005), 0.75 (95% CI = 0.58–0.97, p = 0.027), 0.82 (95% CI = 0.68–0.99, p = 0.039), 0.74 (95% CI = 0.59–0.93, p = 0.011), and 0.79 (95% CI = 0.61–0.95, p = 0.018), respectively.

Conclusion: Using genetic data, this study provides novel causal evidence that adiponectin can protect the kidney function and further reduce the risk of CKD.

Pro-Inflammatory Profile of Adipokines in Obesity Contributes to Pathogenesis, Nutritional Disorders, and Cardiovascular Risk in Chronic Kidney Disease

Obesity is a disease which leads to the development of many other disorders. Excessive accumulation of lipids in adipose tissue (AT) leads to metabolic changes, including hypertrophy of adipocytes, macrophage migration, changes in the composition of immune cells, and impaired secretion of adipokines. Adipokines are cytokines produced by AT and greatly influence human health. Obesity and the pro-inflammatory profile of adipokines lead to the development of chronic kidney disease (CKD) through different mechanisms. In obesity and adipokine profile, there are gender differences that characterize the male gender as more susceptible to metabolic disorders accompanying obesity, including impaired renal function. The relationship between impaired adipokine secretion and renal disease is two-sided. In the developed CKD, the concentration of adipokines in the serum is additionally disturbed due to their insufficient excretion by the excretory system caused by renal pathology. Increased levels of adipokines affect the nutritional status and cardiovascular risk (CVR) of patients with CKD. This article aims to systematize the current knowledge on the influence of obesity, AT, and adipokine secretion disorders on the pathogenesis of CKD and their influence on nutritional status and CVR in patients with CKD.

Mobility performance impacts mortality risk in community-dwelling healthy older adults in Japan: a prospective observational study

BACKGROUND

The timed up and go (TUG) test assesses balance and mobility performance.

AIM

This study aims to investigate the association between TUG time and mortality in Japanese older persons and to clarify possible moderation effects on mortality and TUG time.

METHODS

In all, 874 participants who were ≥ 65 years of age completed the TUG test and had their anthropometric parameters and physical functions measured. We investigated the association between all-cause mortality and TUG using a Cox regression model that included confounders, and explored the time associated with mortality using a restricted cubic spline. We also performed subgroup analyses to explore whether age, sex, and body mass index (BMI) affected the relationship between TUG time and mortality.

RESULTS

The median age and mean follow-up period were 74 and 8.5 years, respectively. Median TUG time was 7.4 s and the prevalence of mortality was 25.7%. TUG time in one second was positively associated with an increased risk of total mortality [hazard ratio (HR): 1.054 (1.016-1.093); P = 0.005] in the Cox regression model. The positive association of mortality and TUG time was present when the TUG was over 10.5 s in the restricted cubic spline curve. Older age (75 years or older) moderated the relationship between TUG time and mortality [P_interaction = 0.096].

CONCLUSION

This study demonstrates that TUG time is associated with all-cause mortality in Japanese older adults.

Comparisons Between Serum Levels of Hepcidin and Leptin in Male College-Level Endurance Runners and Sprinters

Background: Hepcidin-25 is a 25 amino acid hepatokine and a key regulator of iron metabolism related to iron deficiency anemia. Recent studies have suggested that an elevated hepcidin level is correlated with low energy availability. Leptin is an appetite-suppressing adipokine and has been reported to stimulate hepcidin production in animals and cultured cells. While leptin is modulated by exercise, it is known that endurance runners and sprinters practice different types of exercise. This study investigated and compared the relationships between hepcidin and leptin levels, iron status, and body fat to understand better the risk of iron deficiency anemia in endurance runners and sprinters. Methods: Thirty-six male college track and field athletes (15 endurance runners and 21 sprinters) were recruited for this study. Dietary intake, body composition, and blood levels of ferritin, hepcidin-25, leptin, and adiponectin were measured. Correlations between hepcidin levels and ferritin, body fat, leptin, and adiponectin were evaluated using Pearson's correlation coefficient for each group. Results: The endurance runners had lower hepcidin levels and higher leptin and adiponectin levels compared with sprinters. Ferritin was positively correlated with hepcidin-25 levels in both the endurance and sprinter groups. A positive correlation was observed between hepcidin-25 and body fat or leptin levels only in sprinters. Conclusion: This is the first study investigating the relationship between blood levels of hepcidin and leptin in athletes. The positive correlation between hepcidin-25 and leptin was observed in sprinters but not endurance runners.

From diabetes to renal aging: the therapeutic potential of adiponectin

Nowadays, the complications related to diabetes, such as nephropathy, cardiovascular problems, and aging, are highly being considered. Renal cell aging is affected by various mechanisms of inflammation, oxidative stress, and basement membrane thickening, which are significant causes of renal dysfunction in diabetes. Due to recent studies, adiponectin plays a key role in diabetes-related kidney diseases as a fat-derived hormone. In diabetes, reduced adiponectin levels are associated to renal cell aging. Oxidative stress and related signaling pathways are the main routes in which adiponectin may be effective to decline diabetes-associated aging. Therefore, adiponectin signaling in target tissues becomes one of the research areas of interest in metabolism and clinical medicine. Studies on adiponectin signaling will increase our understanding of adiponectin role in diabetes-linked diseases as well as shortening life span conditions which may guide the design of antidiabetic and anti-aging drugs.

Adiponectin affects estimated glomerular filtration rate: A two-sample bidirectional Mendelian randomization study

BACKGROUND

The causal relationship between adiponectin (ADPN) and estimated glomerular filtration rate (eGFR) is unclear. This study adopts a two-sample bidirectional Mendelian randomization (MR) study to explore the causal relationship between ADPN and eGFR.

METHODS

Using eight single nucleotide polymorphisms (SNP) of ADPN and 26 SNP of eGFR as instrumental variables, the study performs a two-sample bidirectional MR study using MR inverse-variance weighted (IVW), MR-Egger and weighted median approach to evaluate the causal relationship between ADPN and eGFR. Using the genetic risk score (GRS) of ADPN and eGFR as instrumental variables, the study performs a second MR analysis to assess the association between ADPN and eGFR.

RESULTS

In ADPN to eGFR MR analysis, the IVW, weighted median and GRS analysis all showed that ADPN had a causal effect on eGFR after removing potential confounders of the ADPN-eGFR relation (IVW: β = .016, P = .002; weighted median: β = .012, P = .022; GRS: β = .016, P = 1.48E-05). As both ADPN and eGFR were natural log-transformed in the corresponding GWAS, eGFR increased by 0.15% for any 10% increase in ADPN. In eGFR to ADPN MR analysis, eGFR had no causal effect on ADPN after removing potential confounders of the eGFR-ADPN relation (All P values > 0.05). The heterogeneity test and sensitivity analysis indicated some heterogeneity, but no directional pleiotropy.

CONCLUSION

Adiponectin has a causal effect on eGFR, while eGFR has no causal effect on ADPN. ADPN may be a clinical target for improving eGFR and treating chronic kidney disease caused by decreased eGFR.

Adiponectin in Chronic Kidney Disease

Adiponectin is the adipokine associated with insulin sensitization, reducing liver gluconeogenesis, and increasing fatty acid oxidation and glucose uptake. Adiponectin is present in the kidneys, mainly in the arterial endothelium and smooth muscle cells, as well as in the capillary endothelium, and might be considered as a marker of many negative factors in chronic kidney disease. The last few years have brought a rising body of evidence that adiponectin is a multipotential protein with anti-inflammatory, metabolic, anti-atherogenic, and reactive oxygen species (ROS) protective actions. Similarly, adiponectin has shown many positive and direct actions in kidney diseases, and among many kidney cells. Data from large cross-sectional and cohort studies showed a positive correlation between serum adiponectin and mortality in chronic kidney disease. This suggests a complex interaction between local adiponectin action, comorbidities, and uremic milieu. In this review we discuss the role of adiponectin in chronic kidney disease.