Thermogenic capacity of human periaortic adipose tissue is transformed by body weight

Fig 1. Morphology of subcutaneous adipose tissue (sWAT) and periaortic adipose tissue (PAT) adipocytes. (A) Representative images of formaldehyde-fixed sWAT and PAT samples obtained from patients with normal (18–24.9 kg/m2), overweight (25–29.9 kg/m2), and obese (>30 kg/m2) body mass index (BMI). (B) Quantification of volume density was performed on the captured images, which were performed by M42 (multipurpose test-system) The percentage of adipocyte volume densities were performed and (*) p<0.05 indicates a statistically significant difference between sWAT and PAT adipocyte volume density. (C) Correlation between BMI and adipocyte volume density in PAT as calculated with Pearson’s correlation (r = -0.91, p<0.01). Data are expressed as mean ± SD (n = 8). A paired t-test was performed to determine differences between averages.

Fig 2. Adipokine and thermogenic mRNA expression in subcutaneous adipose tissue (sWAT) and periaortic adipose tissue (PAT). Quantitative PCR analysis of sWAT and PAT samples showing the expression of some thermogenic, adipokine and inmmune genes. UCP-1, Uncoupling protein 1; PGC-1a, PPARg coactivator 1 alpha; FABP4, fatty acid binding protein 4; IL-4, Interleukin 4; IL-6, Interleukin 6. Quantitative PCR analysis showing the expression of * p<0.05 and ** p<0.01 (n = 8) indicate a statistically significant difference between gene expression levels in sWAT and PAT (mean ± SD).

Fig 3. Protein expression of in subcutaneous adipose tissue (sWAT) and periaortic adipose tissue (PAT). (A) Western Blot was performed in patients with BMI normal (18–24.9) to compare the expression of different proteins. UCP-1, Uncoupling protein 1; PGC-1a PPARg coactivator 1 alpha; FABP4, fatty acid binding protein 4; IL-4, Interleukin 4; IL-6, Interleukin 6; TFAM, transcriptor factor A, mitochondrial precursor; CITED1, CBP/p300 interactive transactivator 1; FGF21, fibroblast growth factor 21. * p<0.05 and ** p< 0,01 mean ± standard deviation (SD) of relative density of antibodies between of sWAT and PAT. In (B), a representative image of Western blot.

Fig 4. Expression of FGF21 and omentin in subcutaneous adipose tissue (sWAT) and periaortic adipose tissue. Representative image showing immunohistochemical staining for FGF21 and omentin (n = 8). A paired t-test was applied to determine significant differences between averages. (***) p<0.001 indicates a statistically significant difference in the levels of FGF21 and omentin expression between sWAT and PAT.

Fig 5. Thermogenic proteins in periaortic adipose tissue. (A) Representative western blots showing PPARg coactivator 1 alpha (PGC-1a) and transcription factor A, mitochondrial (TFAM) levels in total protein extracts from patients with normal (18–25 kg/m2), overweight (25–30 kg/m2), and obese (>30 kg/m2) body mass index (BMI). Extracts were obtained from subcutaneous adipose tissue (sWAT) and PAT adipocyte precursor cells. (B and C) Quantification of relative intensity levels. Data are expressed as mean ± standard deviation (n = 26). * A paired t-test was applied to determine significant differences in the average expression of thermogenic proteins between sWAT and PAT Please see a previous comment.

Fig 6. Expression of thermogenic proteins in periaortic adipose tissue (PAT) and correlation with body mass index (BMI). Based on the data in Fig 5, and the clinical data of patients a Pearson’s correlation analysis between the expression of thermogenic proteins and Body fat % estimation was carried out. Body Fat estimation was calculated by CUN-BAE method [19]. PPARg coactivator 1 alpha (PGC-1a) in male (r = -0.48 p<0.04) and female (r = -0.63, p<0.05) and TFAM in male (r = -0.72, p<0.0008) and female (r = -0.86, p<0.002) decreased significantly with progressive weight gain.