PGC-1α transcriptional response and mitochondrial adaptation to acute exercise is maintained in skeletal muscle of sedentary elderly males

The aim of the present study was to examine the effects of ageing and training status on (1) markers of skeletal muscle mitochondrial content and (2) the ability to activate the acute signalling pathways associated with regulating exercise-induced mitochondrial biogenesis. Muscle biopsies were obtained from the vastus lateralis muscle of young untrained (24 ± 4 years, n = 6; YU), young trained (22 ± 3 years, n = 6; YT), old untrained (65 ± 6 years, n = 6; OU) and old trained (64 ± 3 years, n = 6; OT) healthy males before and after (3 h and 3 days post-exercise) completion of high-intensity interval cycling exercise. In resting muscle, lifelong training preserved mtDNA, PGC-1α and COXIV protein content such that muscles from OT individuals were comparable to muscles from both YU and YT individuals, whereas lifelong sedentary behaviour reduced such markers of mitochondrial content. Regardless of age or training status, acute exercise induced comparable increases in p38MAPK phosphorylation immediately post-exercise, PGC-1α and COXIV mRNA expression at 3 h post-exercise and COXIV protein at 3 days post-exercise. Data demonstrate that lifelong endurance training preserves skeletal muscle PGC-1α content and that despite the mitochondrial dysfunction typically observed with sedentary ageing, muscles from sedentary elderly individuals retain the capacity to activate the acute signalling pathways associated with regulating the early processes of mitochondrial biogenesis. We consider our data to have immediate translational potential as they highlight the potential therapeutic effects of exercise to induce skeletal muscle mitochondrial biogenesis persist late in adulthood, even after a lifetime of physical inactivity.

A comprehensive, contemporary assessment of the association between the presence of hepatosteatosis and the incidence of coronary artery disease on CT coronary angiography

Funding Acknowledgements

Type of funding sources: None.

Background

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing exponentially. The overall prevalence of NAFLD in the United States is predicted to increase to 33.5% of the adult population by 2030. Hepatosteatosis (HS) has been previously shown to be an independent risk factor for cardiovascular disease events. We sought to investigate the association of clinical covariates and the presence of HS and coronary artery disease (CAD) in patients referred for computed tomography coronary angiography (CTCA).

Methods

We performed a retrospective, observational analysis at a high-volume cardiac CT centre analysing consecutive CTCA studies. All patients referred for investigation of chest pain over a 28-month period (June 2014 to November 2016) were included. Covariates in those with CAD and patients without CAD were compared using compared using student"s t-test for continuous variables and chi-squared test for categorical variables. Logistic regression models were constructed for the multivariate analysis.

Results

In total there were 1499 patients referred for CTCA without prior evidence of CAD. Age, male sex, presence of hypertension and diabetes were significantly higher in those with CAD (table 1). HS evaluation was assessed in 1195 (79.7%). In the multivariate analysis significant predictors of CAD were male sex (OR 3.40, p < 0.001), family history (OR 1.90, p = 0.003), current smoking (OR 1.80, p = 0.03) and increasing age (OR 1.12, p < 0.001). The presence of HS was not associated with CAD when adjusted for risk factors (OR 1.05 CI:0.70-1.60, p = 0.80).

Conclusion

We found a significant association between the increasing age, presence of hypertension, male sex, diabetes and current smoking with presence of CAD as detected by CTCA. In contrast to recent evidence HS may not be an independent risk factor for the development of the development of CAD.

Summary statistics of the cohort No CAD (n = 881) CAD (n = 618) P Age (mean (SD)) 48.86 (±12.1) 57.9(±10.6) <0.005* Male Sex (%) 343 (38.6%) 326 (51.1%) <0.005* Hypertension (%) 193(21.9%) 239 (38.7%) <0.005* Diabetes (%) 59 (6.7%) 86 (13.9%) <0.005* Current Smoking (%) 139 (15.8%) 108 (17.5%) 0.423 FHx (%) 239 (27.1%) 167 (27%) 1 HS (%) 291 (33%) 247 (40%) 0.007* A comparison of clinical covariates for the cohort stratified by the presence of coronary artery disease. Statistical significance was assumed when p < 0.05 and is denoted with *.

A comprehensive, contemporary assessment of the association between hepatosteatosis and coronary artery calcium scoring

Funding Acknowledgements

Type of funding sources: None.

onbehalf

Liverpool Multiparametric Imaging Collaboration

Background

Coronary artery calcium (CAC) score is a well-established technique for stratifying an individual’s cardiovascular disease (CVD) risk. Several well-established registries have incorporated CAC scoring into CVD risk prediction models to enhance accuracy. Hepatosteatosis (HS) has been shown to be an independent predictor of CVD events and can be measured on non-contrast computed tomography (CT). We sought to undertake a contemporary, comprehensive assessment of the influence of HS on CAC score alongside traditional CVD risk factors. In patients with HS it may be beneficial to offer routine CAC screening to evaluate CVD risk to enhance opportunities for earlier primary prevention strategies.

Methods

We performed a retrospective, observational analysis at a high-volume cardiac CT centre analysing consecutive CT coronary angiography (CTCA) studies. All patients referred for investigation of chest pain over a 28-month period (June 2014 to November 2016) were included. Patients with established CVD were excluded. The cardiac findings were reported by a cardiologist and retrospectively analysed by two independent radiologists for the presence of HS. Those with CAC of zero and those with CAC greater than zero were compared for demographic and cardiac risks. A multivariate analysis comparing the risk factors was performed to adjust for the presence of established risk factors. A binomial logistic regression model was developed to assess the association between the presence of HS and increasing strata of CAC.

Results

In total there were 1499 patients referred for CTCA without prior evidence of CVD. The assessment of HS was completed in 1195 (79.7%) and CAC score was performed in 1103 (92.3%). There were 466 with CVD and 637 without CVD. The prevalence of HS was significantly higher in those with CVD versus those without CVD on CTCA (51.3% versus 39.9%, p = 0.007). Male sex (50.7% versus 36.1% p= <0.001), age (59.4 ± 13.7 versus 48.1 ± 13.6, p= <0.001) and diabetes (12.4% versus 6.9%, p = 0.04) were also significantly higher in the CAC group compared to the CAC score of zero.

HS was associated with increasing strata of CAC score compared with CAC of zero (CAC score 1-100 OR1.47, p = 0.01, CAC score 101-400 OR:1.68, p = 0.02, CAC score >400 OR 1.42, p = 0.14). This association became non-significant in the highest strata of CAC score.

Conclusion

We found a significant association between the increasing age, male sex, diabetes and HS with the presence of CAC. HS was also associated with a more severe phenotype of CVD based on the multinomial logistic regression model. Although the association reduced for the highest strata of CAC (CAC score >400) this likely reflects the overall low numbers of patients within this group and is likely a type II error.

Based on these findings it may be appropriate to offer routine CVD risk stratification techniques in all those diagnosed with HS.