Leptin levels predict the development of left ventricular hypertrophy in a sample of adult men: the Olivetti Heart Study

Identification of Circulating Plasma Proteins as a Mediator of Hypertension-Driven Cardiac Remodeling: A Mediation Mendelian Randomization Study

BACKGROUND

This study focused on circulating plasma protein profiles to identify mediators of hypertension-driven myocardial remodeling and heart failure.

METHODS

A Mendelian randomization design was used to investigate the causal impact of systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure on 82 cardiac magnetic resonance traits and heart failure risk. Mediation analyses were also conducted to identify potential plasma proteins mediating these effects.

RESULTS

Genetically proxied higher SBP, DBP, and pulse pressure were causally associated with increased left ventricular myocardial mass and alterations in global myocardial wall thickness at end diastole. Elevated SBP and DBP were linked to increased regional myocardial radial strain of the left ventricle (basal anterior, mid, and apical walls), while higher SBP was associated with reduced circumferential strain in specific left ventricular segments (apical, mid-anteroseptal, mid-inferoseptal, and mid-inferolateral walls). Specific plasma proteins mediated the impact of blood pressure on cardiac remodeling, with FGF5 (fibroblast growth factor 5) contributing 2.96% (P=0.024) and 4.15% (P=0.046) to the total effect of SBP and DBP on myocardial wall thickness at end diastole in the apical anterior segment and leptin explaining 15.21% (P=0.042) and 23.24% (P=0.022) of the total effect of SBP and DBP on radial strain in the mid-anteroseptal segment. Additionally, FGF5 was the only mediator, explaining 4.19% (P=0.013) and 4.54% (P=0.032) of the total effect of SBP and DBP on heart failure susceptibility.

CONCLUSIONS

This mediation Mendelian randomization study provides evidence supporting specific circulating plasma proteins as mediators of hypertension-driven cardiac remodeling and heart failure.

Relationship between leptin and white blood cells: a potential role in infection susceptibility and severity-the Olivetti Heart Study

A number of evidence showed an emerging role of leptin on immune system, involving inflammation, and innate and adaptive immunity. Few observational studies have evaluated the relationship between leptin and immunity, albeit with low statistical power and methodological differences. Therefore, the aim of this study was to evaluate the potential role of leptin on the immunity, expressed as white blood cells (WBC)-and its subpopulations, by comprehensive multivariate models in a sample of adult men. A cross-sectional evaluation of a general population comprised 939 subjects participating in the Olivetti Heart Study, with available leptin levels and WBC-and its subpopulations. WBC were significantly and positively associated with leptin, C-reactive protein and HOMA index (p < 0.05), but not with age and anthropometric indices (p > 0.05). The multivariate analysis confirmed the association between leptin and WBC, after accounting for main confounders (p < 0.05). Additional analysis on WBC subpopulations showed a positive and significant correlation between leptin and lymphocytes, monocytes and eosinophils (p < 0.05), but not with neutrophils and basophils (p > 0.05). After stratification by body weight, the positive and significant association between leptin and WBC-and its subpopulations-was found in excess body weight participants. The results of this study indicate a direct relationship between leptin levels and WBC-and its subpopulations-in excess body weight participants. These results support the hypothesis that leptin has modulatory functions on immunity and role in the pathophysiology of immune-related diseases, in particular in those associated with excess body weight.

High leptin status indicates an increased risk of mortality and heart failure in stable coronary artery disease

BACKGROUND AND AIMS

Leptin is an adipocyte-derived peptide involved in energy homeostasis and body weight regulation. The position of leptin in cardiovascular pathophysiology remains controversial. Some studies suggest a detrimental effect of hyperleptinemia on the cardiovascular (CV) system, while others assume the role of leptin as a neutral or even protective factor. We have explored whether high leptin affects the mortality and morbidity risk in patients with stable coronary heart disease.

METHODS AND RESULTS

We followed 975 patients ≥6 months after myocardial infarction or coronary revascularization in a prospective study. All-cause or cardiovascular death, non-fatal cardiovascular events (recurrent myocardial infarction, stroke, or any revascularization), and hospitalizations for heart failure (HF) we used as outcomes. High serum leptin concentrations (≥18.9 ng/mL, i.e., 4th quartile) were associated with worse survival, as well as with a higher incidence of fatal vascular events or hospitalizations for HF. Even after full adjustment for potential covariates, high leptin remained to be associated with a significantly increased 5-years risk of all-cause death [Hazard risk ratio (HRR) 2.10 (95%CIs:1.29-3.42), p < 0.003], CV death [HRR 2.65 (95%CIs:1.48-4.74), p < 0.001], and HF hospitalization [HRR 1.95 (95% CIs:1.11-3.44), p < 0.020]. In contrast, the incidence risk of non-fatal CV events was only marginally and non-significantly influenced [HRR 1.27 (95%CIs:0.76-2.13), p = 0.359].

CONCLUSIONS

High leptin concentration entails an increased risk of mortality, apparently driven by fatal CV events and future worsening of HF, on top of conventional CV risk factors and the baseline status of left ventricular function.

Coronary circulatory function with increasing obesity: A complex U-turn

AIMS

The aim of this investigation was to explore and characterize alterations in coronary circulatory function in function of increasing body weight with medically controlled cardiovascular risk factors and, thus, "metabolically" unhealthy obesity.

MATERIALS AND METHODS

We prospectively enrolled 106 patients with suspected CAD but with normal stress-rest myocardial perfusion on 13 N-ammonia PET/CT and with medically controlled or no cardiovascular risk factors. 13 N-ammonia PET/CT concurrently determined myocardial blood flow (MBF) during pharmacologically induced hyperaemia and at rest. Based on body mass index (BMI), patients were grouped into normal weight (BMI: 20.0-24.9 kg/m2 , n = 22), overweight (BMI: 25.0-29.9 kg/m2 , n = 27), obese (BMI: 30.0-39.9 kg/m2 , n = 31), and morbidly obese (BMI ≥ 40kg/m2 , n = 26).

RESULTS

Resting MBF was comparable among groups (1.09 ± 0.18 vs. 1.00 ± 0.15 vs. 0.96 ± 0.18 vs.. 1.06 ± 0.31 ml/g/min; p = .279 by ANOVA). Compared to normal weight individuals, the hyperaemic MBF progressively decreased in in overweight and obese groups, respectively (2.54 ± 0.48 vs. 2.02 ± 0.27 and 1.75 ± 0.39 ml/g/min; p < .0001), while it increased again in the group of morbidly obese individuals comparable to normal weight (2.44 ± 0.41 vs. 2.54 ± 0.48 ml/g/min, p = .192). The BMI of the study population correlated with the hyperaemic MBF in a quadratic or U-turn fashion (r = .34, SEE = 0.46; p ≤ .002).

CONCLUSIONS

The U-turn of hyperaemic MBF from obesity to morbid obesity is likely to reflect contrasting effects of abdominal versus subcutaneous adipose tissue on coronary circulatory function indicative of two different disease entities, but needing further investigations.