Sex differences in leptin modulate ventilation in heart failure

Usefulness of the predicted percentage ventilatory efficiency for carbon dioxide output during exercise in patients with chronic heart failure

The ventilatory efficiency for carbon dioxide output ([Formula: see text]CO₂) during exercise, as measured by the minute ventilation vs. [Formula: see text]CO₂ slope ([Formula: see text]E vs. [Formula: see text]CO₂ slope), is a powerful prognostic index in patients with chronic heart failure (CHF). This measurement is higher in women than in men, and it increases with age. This study aimed to investigate the usefulness of the predicted value of the percentage [Formula: see text]E vs. [Formula: see text]CO₂ slope (%[Formula: see text]E vs. [Formula: see text]CO₂ slope) as a prognostic index in patients with CHF. A total of 320 patients with CHF and a left ventricular ejection fraction (LVEF) < 45% (male, 85.6%; mean age, 64.6 years) who underwent symptom-limited cardiopulmonary exercise tests using a cycle ergometer were included in the study. The %[Formula: see text]E vs. [Formula: see text]CO₂ was calculated using predictive formulae based on age and sex. Cardiovascular-related death was defined as the primary endpoint. The mean follow-up duration was 7.5 ± 3.3 years. Of 101 patients who died during the study period, 75 experienced cardiovascular-related deaths. The average [Formula: see text]E vs. [Formula: see text]CO₂ slope was 32.8 ± 8.0, and the average %[Formula: see text]E vs. [Formula: see text]CO₂ slope was 119.6 ± 28.2%. The cumulative incidence of cardiovascular-related death after 10 years of follow-up were 44.7% (95% CI 34.4-54.6%) in patients with %[Formula: see text]E vs. [Formula: see text]CO₂ slope > 120 and 15.0% (95% CI 9.4-21.8%) in patients with %[Formula: see text]E vs. [Formula: see text]CO₂ slope ≤ 120. The multivariate Cox regression analysis indicated that a %[Formula: see text]E vs. [Formula: see text]CO₂ slope > 120 was an independent predictor of cardiovascular-related death (adjusted hazard ratio, 3.24; 95% confidence interval 1.65-6.67; p < 0.01). The %[Formula: see text]E vs. [Formula: see text]CO₂ slope can be used for risk stratification in patients with CHF and an LVEF < 45%.

Role of Leptin as a Link between Asthma and Obesity: A Systematic Review and Meta-Analysis

Asthma and obesity are considered as highly prevalent diseases with a great impact on public health. Obesity has been demonstrated to be an aggravating factor in the pathogenesis of asthma. Adipose tissue secretes proinflammatory cytokines and mediators, including leptin, which may promote the development and severity of asthma in obese patients. This study is a systematic review and a meta-analysis based on the relationship between leptin and asthma during obesity. MEDLINE, Cochrane, EMBASE and CINAHL databases were used. Data heterogeneity was analyzed using Cochran’s Q and treatment effect with the DerSimonian and Laird method. Random effect analyses were carried out to test data sensitivity. Asymmetry was estimated using Begg’s and Egger’s tests. All studies showed significant differences in leptin levels. The effect of the measures (p < 0.001), data sensitivity (p < 0.05) and data asymmetry were statistically significant, as well as tBegg’s test (p = 0.010) and Egge’s test (p < 0.001). Despite the existing limiting factors, the results of this study support the relevant role of leptin in the pathophysiology of asthma in obese subjects. Nevertheless, further studies are needed to obtain better insight in the relationship between leptin and asthma in obesity.

Do Leptin Play a Role in Metabolism-Related Psychopathological Symptoms?

Objectives: Leptin is a crucial regulator of energy balance and is associated with obesity. In recent years, it has also been recognized as involved in the psychopathological mechanism. Our study aimed to elucidate the relationships between serum leptin levels, body mass index (BMI), and psychopathology symptoms in patients with schizophrenia. Methods: A cross-sectional assessment of 324 inpatients with schizophrenia was conducted. Schizophrenia symptoms were measured using the Positive and Negative Syndrome Scale (PANSS) and the Brief Psychiatric Rating Scale (BPRS). Serum leptin levels were assessed by the Enzyme-Linked Immunosorbent Assay (ELISA). Results: Significant differences in sex, BMI, and negative symptom subscale (PANSS-N) scores were found between the groups with high and low leptin levels in the study. Leptin levels were positively correlated with BMI (B = 2.322, t = 9.557, P < 0.001) and negatively correlated with PANSS-N scores (B = -0.303, t = -2.784, P = 0.006). Conclusions: Our results suggest that the increase in leptin levels is responsible for antipsychotic-induced weight gain and improved psychopathological symptoms.

Ventilatory efficiency during ramp exercise in relation to age and sex in a healthy Japanese population

BACKGROUND

The current understanding of ventilator efficiency variables during ramp exercise testing in the normal Japanese population is insufficient, and the responses of tidal volume (VT) and minute ventilation (V̇E) to the ramp exercise test in the normal Japanese population are not known.

METHODS

A total of 529 healthy Japanese subjects aged 20-78 years underwent cardiopulmonary exercise testing using a cycle ergometer with ramp protocols. VT and V̇E at rest, at anaerobic threshold, and at peak exercise were determined. The slope of V̇E versus carbon dioxide (V̇CO₂) (V̇E vs. V̇CO₂ slope), minimum V̇E/V̇CO₂, and oxygen uptake efficiency slope (OUES) were determined.

RESULTS

For males and females in their 20 s, peak VT (VTpeak) was 2192 ± 376 and 1509 ± 260 mL (p < 0.001), peak V̇E (V̇Epeak) was 80.6 ± 18.7 and 57.7 ± 13.9 L/min (sex differences p < 0.001), the V̇E vs. V̇CO₂ slope was 24.4 ± 3.2 and 25.7 ± 3.2 (p = 0.035), the minimum V̇E/V̇CO₂ was 24.2 ± 2.3 and 27.0 ± 2.8 (p < 0.001), and the OUES was 2452 ± 519 and 1991 ± 315 (p < 0.001), respectively. VTpeak and V̇Epeak decreased with age and increased with weight and height. The V̇E vs. V̇CO₂ slope and minimum V̇E/V̇CO₂ increased with age, while conversely, the OUES decreased with age.

CONCLUSIONS

We have established the normal range of VT and V̇E responses, the V̇E vs. V̇CO₂ slope, the minimum V̇E/V̇CO₂, and the OUES for a healthy Japanese population. Some of these parameters were influenced by weight, height, sex, and age. These results provide useful reference values for interpreting the results of cardiopulmonary exercise testing in cardiac patients.

Leptin, cardiovascular diseases and type 2 diabetes mellitus

Leptin, an adipokine that is implicated in the control of food intake via appetite suppression, may also stimulate oxidative stress, inflammation, thrombosis, arterial stiffness, angiogenesis and atherogenesis. These leptin-induced effects may predispose to the development of cardiovascular diseases. In the present review we discuss the evidence linking leptin levels with the presence, severity and/or prognosis of both coronary artery disease and non-cardiac vascular diseases such as stroke, carotid artery disease, peripheral artery disease (PAD) and abdominal aortic aneurysms (AAA) as well as with chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM). Leptin levels have been positively associated with the presence, severity, extent and lesion complexity of coronary atherosclerosis as well as with the presence, severity and poor clinical outcomes of both ischemic and hemorrhagic strokes. But conflicting results also exist. Furthermore, leptin was reported to independently predict common carotid intima-media thickness and carotid plaque instability. A link between hyperleptinemia and PAD has been reported, whereas limited data were available on the potential association between leptin and AAA. Elevated leptin concentrations have also been related to CKD incidence and progression as well as with insulin resistance, T2DM, micro- and macrovascular diabetic complications. Statins and antidiabetic drugs (including sitagliptin, metformin, pioglitazone, liraglutide and empagliflozin) may affect leptin levels. Further research is needed to establish the potential use (if any) of leptin as a therapeutic target in these diseases.

Low Plasma Leptin and High Soluble Leptin Receptor Levels Are Associated With Mild Cognitive Impairment in Type 2 Diabetic Patients

Background: Metabolic disturbances, such as hyperglycemia, hyperlipidemia, and obesity, are thought to be risk factors for Alzheimer's disease.

Objective: This study aimed to investigate whether adipokine leptin and soluble leptin receptor (sOBR) levels are correlated with mild cognitive impairment (MCI) and metabolic status of the patients of type 2 diabetes mellitus (T2DM).

Methods: Total of 169 T2DM patients were recruited and divided according to the Montreal Cognitive Assessment (MoCA) score. Their cognition and metabolic parameters were extensively assessed. Plasma leptin and sOBR levels were determined by RIA and ELISA, respectively. Free leptin index (FLI) was calculated.

Results: Of 124 enrolled T2DM patients, 61 were diagnosed with MCI (MoCA < 26). In MCI group and female subgroup, leptin levels and FLI were significantly lower and sOBR concentrations were higher when compared with their respective health cognition controls (all p < 0.05). Leptin levels and FLI were positively associated with the most cognitive domains and their Waist-to-Hip Ratio (WHR), a traditional index of central obesity. Leptin, sOBR, and WHR were independent variables of MCI in all individuals (all p < 0.05). For the females, MoCA was also positively correlated with leptin (β = 0.893, p < 0.001) and negatively correlated with WHR (β = −0.363, p = 0.014). Leptin was positively correlated only with WHR (β = 0.441, p = 0.025).

Conclusions: This study showed that a high level of leptin and low level of sOBR are associated with the improved cognitive function in T2DM patients and more significantly in female individuals, while WHR, as an indicator of the visceral obesity, contributes to cognitive deficits.

Trial registration: Advanced Glycation End Products Induced Cognitive Impairment in Diabetes: BDNF Signal Meditated Hippocampal Neurogenesis ChiCTR-OCC-15006060; http://www.chictr.org.cn/showproj.aspx?proj=10536.