Prognostic significance of adipocytokines in systolic heart failure patients

Causal Associations Between Circulating Adipokines and Cardiovascular Disease: A Mendelian Randomization Study

CONTEXT

Observational studies have suggested associations between adipokines and cardiovascular disease (CVD), but the roles of certain adipokines remain controversial, and these associations have not yet been ascertained causally.

OBJECTIVE

To investigate whether circulating adipokines causally affect the risk of CVD using 2-sample Mendelian randomization (MR).

METHODS

Independent genetic variants strongly associated with adiponectin, resistin, chemerin, and retinol binding protein 4 (RBP4) were selected from public genome-wide association studies. Summary-level statistics for CVD, including coronary artery disease (CAD), myocardial infarction, atrial fibrillation (AF), heart failure (HF), and stroke and its subtypes were collected. The inverse-variance weighted and Wald ratio methods were used for the MR estimates. The MR pleiotropy residual sum and outlier, weighted median, MR-Egger, leave-one-out analysis, MR Steiger, and colocalization analyses were used in the sensitivity analysis.

RESULTS

Genetically predicted resistin levels were positively associated with AF risk (odds ratio [OR] 1.09; 95% confidence interval [CI], 1.04-1.13; P = 4.1 × 10-5), which was attenuated to null after adjusting for blood pressure. We observed suggestive associations between higher genetically predicted chemerin levels and an increased risk of CAD (OR 1.27; 95% CI, 1.01-1.60; P = 0.040), higher genetically predicted RBP4 levels and an increased risk of HF (OR 1.14; 95% CI, 1.02-1.27; P = 0.024). There was no causal association between genetically predicted adiponectin levels and CVD risk.

CONCLUSIONS

Our findings reveal the causal association between resistin and AF, probably acting through blood pressure, and suggest potential causal associations between chemerin and CAD, RBP4, and HF.

Associations between circulating resistin concentrations and left ventricular mass are not accounted for by effects on aortic stiffness or renal dysfunction

Background

Although, in-part through an impact on left ventricular mass (LVM), resistin (an adipokine) may contribute to heart failure, whether this is explained by the adverse effects of resistin on aortic stiffness and renal function is unknown.

Methods

Relationships between circulating resistin concentrations and LVM index (LVMI), and LVM beyond that predicted by stroke work (inappropriate LVM [LVM_inappr]) (echocardiography) were determined in 647 randomly selected community participants, and in regression analysis, the extent to which these relations could be explained by aortic pulse wave velocity (PWV) or estimated glomerular filtration rate (eGFR) was evaluated.

Results

Independent of confounders, resistin concentrations were independently associated with LVMI, LVM_inappr, LV hypertrophy (LVH), PWV and eGFR. Furthermore, independent of confounders, LVMI, LVM_inappr and LVH were independently associated with PWV and eGFR. However, adjustments for either PWV or eGFR failed to modify the relationships between resistin concentrations and LVMI, LVM_inappr or LVH. Moreover, in multivariate regression analysis neither PWV nor eGFR significantly modified the contribution of resistin to LVM_inappr or LVMI.

Conclusions

Independent relationships between circulating concentrations of the adipocytokine resistin and LVM are not explained by the impact of resistin on ventricular-vascular coupling or renal dysfunction. Resistin’s effects on LVM are therefore likely to be through direct actions on the myocardium.

Human resistin in chemotherapy-induced heart failure in humanized male mice and in women treated for breast cancer

Resistin is a circulating mediator of insulin resistance mainly expressed in human monocytes and responsive to inflammatory stimuli. Recent clinical studies have connected elevated resistin levels with the development and severity of heart failure. To further our understanding of the role of human resistin in heart failure, we studied a humanized mouse model lacking murine resistin but transgenic for the human Retn gene (Hum-Retn mice), which exhibits basal and inflammation-stimulated resistin levels similar to humans. Specifically, we explored whether resistin underlies acute anthracycline-induced cardiotoxicity. Remarkably, doxorubicin (25mg/kg ip) led to a 4-fold induction of serum resistin levels in Hum-Retn mice. Moreover, doxorubicin-induced cardiotoxicity was greater in the Hum-Retn mice than in littermate controls not expressing human resistin (Retn(-/-)). Hum-Retn mice showed increased cardiac mRNA levels of inflammatory and cell adhesion genes compared with Retn(-/-) mice. Macrophages, but not cardiomyocytes, from Hum-Retn mice treated with doxorubicin in vitro showed dramatic induction of hRetn (human resistin) mRNA and protein expression. We also examined resistin levels in anthracycline-treated breast cancer patients with and without cardiotoxicity. Intriguingly, serum resistin levels in women undergoing anthracycline-containing chemotherapy increased significantly at 3 months and remained elevated at 6 months in those with subsequent cardiotoxicity. Further, elevation in resistin correlated with decline in ejection fraction in these women. These results suggest that elevated resistin is a biomarker of anthracycline-induced cardiotoxicity and may contribute in the development of heart failure via its direct effects on macrophages. These results further implicate resistin as a link between inflammation, metabolism, and heart disease.