Marta Jonas

SIRT1 and SIRT7 expression in adipose tissues of obese and normal-weight individuals is regulated by microRNAs but not by methylation status

Background/Objective:Given their importance in the regulation of metabolism, sirtuins (SIRTs) constitute promising subjects of research on the pathogenesis of obesity and the metabolic syndrome. The aim of this study was to assess whether obesity in humans is associated with changes in the expression of SIRT genes in adipose tissue and whether epigenetic mechanisms, DNA methylation and microRNA (miRNA) interference, mediate in this phenomenon.Subjects/Methods:The expression of SIRTs and of SIRT1 and SIRT7 mRNA-interacting miRNAs was evaluated by real-time PCR in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) of 58 obese (body mass index (BMI) >40 kg m−2) and 31 normal-weight (BMI 20–24.9 kg m−2) individuals. The methylation status of SIRTs was studied by the methylation-sensitive digestion/real-time PCR method.Results:SIRT1 mRNA levels were lower in adipose tissues of obese patients than of normal-weight controls (VAT: P=0.0002, SAT: P=0.008). In contrast, expression of SIRT7 was higher in adipose tissues of obese patients than in the control group (VAT: P=0.001, SAT: P=0.008). The mean methylation of the SIRT1 and SIRT7 CpG islands was similar in tissues with high and low expression of these genes, and there was no correlation between the level of expression and the level of methylation. On the other hand, expression of SIRT1 in VAT of obese subjects correlated negatively with the expression of miR-22-3p (P<0.0001, rs=−0.514), miR-34a-5p (P=0.01, rs=−0.326) and miR-181a-3p (P<0.0001, rs=−0.536). In turn, expression of SIRT7 in VAT of slim individuals correlated negatively with the expression of miR-125a-5p (P=0.003, rs=−0.562) and miR-125b-5p (P=0.018, rs=−0.460).Conclusions:We observed obesity-associated downregulation of SIRT1 and upregulation of SIRT7 mRNA levels that were not associated with the methylation status of their promoters. We found a negative correlation between mRNA levels of SIRT1 in VAT of obese individuals and SIRT7 in VAT of the normal-weight subjects and expression of the relevant miRNAs.

Interleukins 6 and 15 Levels Are Higher in Subcutaneous Adipose Tissue, but Obesity Is Associated with Their Increased Content in Visceral Fat Depots

Excess adiposity is associated with chronic inflammation, which takes part in the development of obesity-related complications. The aim of this study was to establish whether subcutaneous (SAT) or visceral (VAT) adipose tissue plays a major role in synthesis of pro-inflammatory cytokines. Concentrations of interleukins (IL): 1β, 6, 8 and 15 were measured at the protein level by an ELISA-based method and on the mRNA level by real-time PCR in VAT and SAT samples obtained from 49 obese (BMI > 40 kg/m2) and 16 normal-weight (BMI 20–24.9 kg/m2) controls. IL-6 and IL-15 protein concentrations were higher in SAT than in VAT for both obese (p = 0.003 and p < 0.0001, respectively) and control individuals (p = 0.004 and p = 0.001, respectively), while for IL-1β this was observed only in obese subjects (p = 0.047). What characterized obese individuals was the higher expression of IL-6 and IL-15 at the protein level in VAT compared to normal-weight controls (p = 0.047 and p = 0.016, respectively). Additionally, obese individuals with metabolic syndrome had higher IL-1β levels in VAT than did obese individuals without this syndrome (p = 0.003). In conclusion, concentrations of some pro-inflammatory cytokines were higher in SAT than in VAT, but it was the increased pro-inflammatory activity of VAT that was associated with obesity and metabolic syndrome.

Cognitive Performance and Functional Status Are the Major Factors Predicting Survival of Centenarians in Poland

BACKGROUND Clinical and biochemical predictors of extreme longevity would be useful in geriatric practice but have still not been clearly defined. METHODS To identify the best nongenetic predictors of survival in centenarians, we examined 340 individuals aged 100+ years. A detailed questionnaire was completed, and comprehensive geriatric assessment and blood analyses were performed. Survival of study participants was checked annually over the period of 10 years. RESULTS In the univariate Cox proportional hazards model, a longer survival of centenarians was correlated with a higher adjusted Mini-Mental State Examination (MMSE(adj)) score (p < .000001), higher Activities of Daily Living (ADL) and adjusted Instrumental Activities of Daily Living (IADL(adj)) scores (p < .000001 and p = .00008, respectively), and younger age at the time of testing (p = .005). Blood pressure, lipid profile, and C-reactive protein and hemoglobin concentrations were not associated with survival. Multivariate analysis including age, sex, and the MMSE(adj) and ADL scores showed that both MMSE(adj) and ADL predicted survival (HR = 0.978 per each MMSE(adj) point, 95% CI: 0.964-0.993, p = .004; HR = 0.900 per each ADL point, 95% CI: 0.842-0.962, p = .002, respectively). In multivariate analysis with the ADL score substituted by the IADL(adj) score, the only predictor of survival was MMSE(adj) (HR = 0.973 per each MMSE(adj) point, 95% CI: 0.958-0.988, p = .0006). CONCLUSIONS Cognitive and functional performances are predictors of survival in centenarians.

Age-related changes of leptin and leptin receptor variants in healthy elderly and long-lived adults

Aging is usually associated with hyperleptinemia and leptin resistance, both increasing the risk of age‐related diseases. It was relevant to establish if healthily aging, non‐obese individuals develop changes in leptin, the soluble leptin receptor (OB‐Re), free leptin index (FLI), in methylation of the leptin receptor gene (LEPR) promoter, and in the expression of long (OB‐Rb) and short (OB‐Ra) leptin receptor isoforms.

NGS Reveals Molecular Pathways Affected by Obesity and Weight Loss-Related Changes in miRNA Levels in Adipose Tissue

Both obesity and weight loss may cause molecular changes in adipose tissue. This study aimed to characterize changes in adipose tissue miRNome in order to identify molecular pathways affected by obesity and weight changes. Next generation sequencing (NGS) was applied to identify microRNAs (miRNAs) differentially expressed in 47 samples of visceral (VAT) and subcutaneous (SAT) adipose tissues from normal-weight (N), obese (O) and obese after surgery-induced weight loss (PO) individuals. Subsequently miRNA expression was validated by real-time PCR in 197 adipose tissues and bioinformatics analysis performed to identify molecular pathways affected by obesity-related changes in miRNA expression. NGS identified 344 miRNAs expressed in adipose tissues with ≥5 reads per million. Using >2 and <−2 fold change as cut-offs we showed that the expression of 54 miRNAs differed significantly between VAT-O and SAT-O. Equally, between SAT-O and SAT-N, the expression of 20 miRNAs differed significantly, between SAT-PO and SAT-N the expression of 79 miRNAs differed significantly, and between SAT-PO and SAT-O, the expression of 61 miRNAs differed significantly. Ontological analyses disclosed several molecular pathways regulated by these miRNAs in adipose tissue. NGS-based miRNome analysis characterized changes of the miRNA profile of adipose tissue, which are associated with changes of weight possibly responsible for a differential regulation of molecular pathways in adipose tissue when the individual is obese and after the individual has lost weight.