Circulating Irisin Concentrations Are Associated with a Favourable Lipid Profile in the General Population

<div><p>Background/aims</p><p>Irisin is a myokine, which is mainly inversely associated with the risk for non-communicable diseases. Irisin improves cellular energy metabolism by uncoupling the mitochondrial respiratory chain resulting in increased energy expenditure using lipids. To date potential associations between irisin concentration and lipid profile are poorly understood. Therefore, this investigation aimed to evaluate potential associations between irisin and lipid levels in the general population.</p><p>Methods</p><p>Data of 430 men and 537 women from the population-based Study of Health in Pomerania (SHIP-TREND) with available irisin and lipid concentrations were used. Analyses of variance, linear and logistic regression models adjusted for age, HBA1c, waist circumference, physical activity, smoking, alcohol consumption, systolic blood pressure, ALAT were calculated.</p><p>Results</p><p>We detected significantly inverse associations between irisin and circulating levels of total [beta coefficient 0.21 (standard error 0.08), p = 0.01], low-density cholesterol [-0.16 (0.07), p = 0.03] and triglycerides [-0.17 (0.08), p = 0.02] for men. Females without lipid lowering medication had an inverse association between irisin and total cholesterol [-0.12 (0.06), p = 0.05]. Further, male subjects with irisin concentrations in the third tertile had an increased odds for elevated low-density cholesterol [odds ratio 1.96 (95% confidence interval 1.07–3.48), p = 0.03) and triglyceride [1.95 (1.09–3.47), p = 0.02] levels, even after exclusion of subjects with lipid lowering medication. In addition, our data revealed an annual rhythm of serum irisin levels with peak levels arise in winter and summer months.</p><p>Conclusion</p><p>This is the first investigation to report a significant association between circulating irisin and a favourable lipid profile in the general population. This may infer that higher irisin concentrations are associated with a reduced risk for non-communicable diseases.</p></div

Association between irisin concentrations and lipid levels as well as dyslipidemia.

<p>Association between irisin concentrations and lipid levels as well as dyslipidemia.</p

Association between irisin concentrations and lipid levels.

<p>Association between irisin concentrations and lipid levels.</p

Baseline Characteristics stratified by sex.

<p>Baseline Characteristics stratified by sex.</p

Boxplots of irisin concentrations separately for men and women by month.

<p>*p<0.05 for comparison between men and women. The black triangles indicate group means.</p

Association between irisin concentrations and levels of total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) cholesterol and triglyceride among men and women.

<p><i>Left side of each lipid</i>: Estimated mean levels with 95% confidence interval by tertiles of irisin. <i>Right side of each lipid</i>: Linear regression. All models were adjusted for age, HBA1c, waist circumference, physical activity, smoking, alcohol consumption, systolic blood pressure, ALAT and months of examination (only linear regression).</p

An overview of the automated breast density evaluation framework.

<p>The approach consists of three main steps: segmentation and bias field correction, breast tissue delineation, and fibroglandular tissue extraction. The results of the bias field correction (Step 1) are used both for breast tissue (Step 2) and parenchyma (Step 3) extraction. In Step 3, the results of Steps 1 and 2 are utilized for parenchyma extraction. The data flow is schematically explained by the lines, connecting the pipeline steps.</p

An example of breast tissue (upper row) and fibroglandular tissue (lower row) segmentation results.

<p>The results are overlaid in 2D and 3D with the original data.</p

Coefficients of the regression lines of the differences.

<p>Coefficients of the regression lines of the difference between the two methods on the average of the two methods for BV and PV.</p><p>Coefficients of the regression lines of the differences.</p

Another intensity inhomogeneity example.

<p>The intensities of the breast tissue close to the breast air boundaries (marked by the red rectangle) have higher values than the intensities of the breast tissue located in the middle of the breast.</p