Association between visceral adipose tissue volume, measured using computed tomography, and cardio-metabolic risk factors

Impact of Visceral and Hepatic Fat on Cardiometabolic Health

PURPOSE OF REVIEW

Body fat distribution plays a significant role in the cardiometabolic consequences of obesity. We review the impact of visceral and hepatic fat and highlight important interventions.

RECENT FINDINGS

Several epidemiologic studies have established a clear association between visceral fat and cardiovascular disease. The association between hepatic fat and cardiovascular disease is less clear with discordant results. Novel evidence demonstrates sodium glucose co-transporter-2 (SGLT2) inhibitors facilitate modest weight loss and reductions in ectopic fat depots in patient with type 2 diabetes. Glucagon-like peptide-1 (GLP-1) receptor agonists have been associated with decreased visceral/hepatic fat and reductions in MACE in populations with type 2 diabetes and with overweight/obesity. Clear associations between visceral fat and cardiometabolic outcomes have been established, whereas the impact of hepatic fat remains less clear. Lifestyle modification and pharmacologic interventions remain the initial therapies, while surgical intervention is associated with improved long-term outcomes. Emerging therapies have demonstrated a profound impact on body fat distribution and cardiometabolic risk.

Near-infrared reactance spectroscopy-derived visceral adipose tissue for the assessment of metabolic syndrome in a multi-ethnic sample of young adults

OBJECTIVES

Visceral adipose tissue (VAT) is highly associated with metabolic syndrome (MetS), which is rapidly increasing in young adults. However, accessible VAT measurement methods are limited, restricting the use of VAT in early detection. This cross-sectional study sought to determine if near-infrared reactance spectroscopy (NIRS)-derived VAT (VATNIRS) was associated with MetS in a multi-ethnic sample of young adults.

METHODS

A total of 107 male and female (F:62, M:45) participants (age: 23.0 ± 4.3y; BMI: 27.1 ± 6.6 kg/m2) completed measurements of fasting blood pressure, blood glucose (FBG), blood lipids, and anthropometric assessments including waist circumference and VATNIRS. MetS severity (MetSindex) was calculated from the aforementioned risk factors using sex and race-specific equations.

RESULTS

VATNIRS was higher in participants with, and at risk for, MetS compared to those with lower risks (all p < .001). VATNIRS was positively associated with MetSindex for all groups (all p < .001). VATNIRS showed positive associations with systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP), LDL-C and LDL-C-related biomarkers, and FBG; and negative associations with HDL-C and HDL-C-to-total cholesterol ratio (all p < .050). Associations between VATNIRS and blood pressure for females, and LDL-C and LDL-C-related biomarkers for males, were nonsignificant (all p > .050). VATNIRS was positively associated with DBP in African-American participants, and SBP in White participants, resulting in positive associations with MAP for both groups (all p < .050).

CONCLUSIONS

VATNIRS is associated with MetS and individual MetS risks factors in a multi-ethnic sample of young adults; providing a noninvasive, cost-effective, portable, and accessible method that may assist in the early detection of MetS and other cardiometabolic abnormalities.

Circadian misalignment impacts the association of visceral adiposity with metabolic syndrome in adolescents

STUDY OBJECTIVES

Although insufficient sleep is a risk factor for metabolic syndrome (MetS), the circadian timing of sleep (CTS) is also involved in cardiac and metabolic regulation. We examined whether delays and deviations in the sleep midpoint (SM), a measure of CTS, modify the association between visceral adipose tissue (VAT) and MetS in adolescents.

METHODS

We evaluated 277 adolescents (median 16 years) who had at least 5 nights of at-home actigraphy (ACT), in-lab polysomnography (PSG), dual-energy X-ray absorptiometry (DXA) scan, and MetS score data. Sleep midpoint (SM), sleep irregularity (SI), and social jetlag (SJL) were examined as effect modifiers of the association between VAT and MetS, including waist circumference, blood pressure, insulin resistance, triglycerides, and cholesterol. Linear regression models adjusted for demographics, ACT-sleep duration, ACT-sleep variability, and PSG-apnea-hypopnea index.

RESULTS

The association between VAT and MetS was significantly stronger (p-values for interactions < 0.001) among adolescents with a schooldays SM later than 4:00 (2.66 [0.30] points increase in MetS score), a SI higher than 1 hour (2.49 [0.30]) or a SJL greater than 1.5 hours (2.15 [0.36]), than in those with an earlier SM (<3:00; 1.76 [0.28]), lower SI (<30 minutes; 0.98 [0.70]), or optimal SJL (<30 minutes; 1.08 [0.45]).

CONCLUSIONS

A delayed sleep phase, an irregular sleep-wake cycle, and greater social jetlag on schooldays identified adolescents in whom VAT had a stronger association with MetS. Circadian misalignment is a risk factor that enhances the impact of visceral obesity on cardiometabolic morbidity and should be a target of preventative strategies in adolescents.

The Multifaceted S100B Protein: A Role in Obesity and Diabetes?

The S100B protein is abundant in the nervous system, mainly in astrocytes, and is also present in other districts. Among these, the adipose tissue is a site of concentration for the protein. In the light of consistent research showing some associations between S100B and adipose tissue in the context of obesity, metabolic disorders, and diabetes, this review tunes the possible role of S100B in the pathogenic processes of these disorders, which are known to involve the adipose tissue. The reported data suggest a role for adipose S100B in obesity/diabetes processes, thus putatively re-proposing the role played by astrocytic S100B in neuroinflammatory/neurodegenerative processes.

Visceral adipose tissue increases the risk of periodontal disease: Results from the 2011-2014 National Health and Nutrition Examination Survey and Mendelian randomization analysis

AIM

This study aimed to investigate the relationship and potential causal effect of visceral adipose tissue (VAT) on periodontal disease (PD). Despite prior research on this, there has been no definitive conclusion. Therefore, this study aimed to provide additional insight into these associations.

MATERIALS AND METHODS

This study used data from the National Health and Nutrition Examination Survey 2011-2014 to examine the association between VAT and PD in a cross-sectional study design. Various analytical methods were employed, such as multivariable logistic regression, restricted cubic spline analysis, and p-value for trend. Additionally, two-sample Mendelian randomization (MR) analysis was performed to evaluate the potential causal effect of VAT on PD risk. These methods enabled us to evaluate the association between VAT and PD and to establish whether VAT could be a causal factor in PD development.

RESULTS

The study examined a sample of 3535 participants, and the findings suggested that higher VAT levels were associated with an increased risk of PD. In addition, multivariable regression analysis conducted in six models revealed a statistically significant association between VAT and PD risk. Restricted cubic spline analysis showed an inverted U-shaped association between VAT and PD, with a turning point at 733 g of VAT. Finally, a two-sample MR analysis provided evidence for a potential causal relationship between VAT and PD risk, with an odds ratio of 1.16 (95% confidence interval: 1.02-1.33, p = .027) per kg increase in genetically predicted VAT.

CONCLUSIONS

The results of this study suggest that there is a significant association between VAT and PD and that VAT could be a potential causal factor in PD risk. Our results also suggest that although there is a potential link between VAT levels and PD risk, the effect size is modest. Therefore, interventions designed to reduce VAT levels should not be considered a primary strategy for PD risk reduction but could be one of many strategies used in a comprehensive approach to PD risk management.

Relationships of rapid eating with visceral and subcutaneous fat mass and plasma adiponectin concentration

Rapid eating has been demonstrated to be associated with obesity and overweight. However, few studies have characterized the separate relationships of eating speed with visceral and subcutaneous fat mass or circulating adiponectin concentration. We hypothesized that rapid eating is associated with the larger visceral fat tissue (VFT) area and lower adiponectin concentration, but not with the subcutaneous fat tissue (SFT) area in men and women. We performed a cross-sectional study of 712 adults aged 20-86 years (528 men and 184 women; mean ± SD age 59.36 ± 13.61 years). The participants completed a self-reported questionnaire, and underwent anthropometric and laboratory measurements and computed tomographic imaging of the abdomen as a part of annual medical check-ups. Multivariate linear regression analyses revealed that rapid eating was associated with larger visceral (B = 24.74; 95% CI 8.87-40.61, p = 0.002) and subcutaneous fat areas (B = 31.31; 95% CI 12.23-50.38, p = 0.001), lower adiponectin concentration (B =  - 2.92; 95% CI - 4.39- - 1.46, p < 0.001), higher body mass index (BMI) (B = 2.13; 95% CI 1.02-3.25, p < 0.001), and larger waist circumference (B = 5.23; 95% CI 2.16-8.30, p < 0.001) in men, which is partially consistent with the hypothesis. In contrast, rapid eating was found to be associated only with BMI, and not with abdominal adipose area or adiponectin concentration in women, which is a result that is not consistent with the hypothesis. These results suggest that there is no difference in the association of rapid eating with VFT and SFT areas.

Fat Hounsfield Unit Reference Interval Derived through an Indirect Method

BACKGROUND

In vivo Hounsfield Unit (HU) values have traditionally been determined using direct CT image measurements. These measurements are dependent on the window/level used to examine the CT image and the individual conducting the fat tissue tracing.

METHODS

Using an indirect method, a new reference interval (RI) is proposed. A total of 4000 samples of fat tissues were collected from routine abdominal CT examinations. A linear regression equation was then calculated using the linear part of the cumulative frequency plot of their average values.

RESULTS

The regression function for total abdominal fat was determined to be y = 35.376*x - 123.48, and a 95% confidence RI of -123 to -89 was computed. A significant difference of 3.82 was observed between the average fat HU values of visceral and subcutaneous areas.

CONCLUSIONS

Using statistical methods and the in vivo measurements of patient data, a series of RIs were determined for fat HU that is consistent with theoretical values.

Circadian Misalignment Impacts the Association of Visceral Adiposity With Elevated Blood Pressure in Adolescents

BACKGROUND

Although insufficient sleep has been shown to contribute to obesity-related elevated blood pressure, the circadian timing of sleep has emerged as a novel risk factor. We hypothesized that deviations in sleep midpoint, a measure of circadian timing of sleep, modify the association between visceral adiposity and elevated blood pressure in adolescents.

METHODS

We studied 303 subjects from the Penn State Child Cohort (16.2±2.2 years; 47.5% female; 21.5% racial/ethnic minority). Actigraphy-measured sleep duration, midpoint, variability, and regularity were calculated across a 7-night period. Visceral adipose tissue (VAT) was measured with dual-energy X-ray absorptiometry. Systolic blood pressure (SBP) and diastolic blood pressure levels were measured in the seated position. Multivariable linear regression models tested sleep midpoint and its regularity as effect modifiers of VAT on SBP/diastolic blood pressure levels, while adjusting for demographic and sleep covariables. These associations were also examined as a function of being in-school or on-break.

RESULTS

Significant interactions were found between VAT and sleep irregularity, but not sleep midpoint, on SBP (P interaction=0.007) and diastolic blood pressure (P interaction=0.022). Additionally, significant interactions were found between VAT and schooldays sleep midpoint on SBP (P interaction=0.026) and diastolic blood pressure (P interaction=0.043), whereas significant interactions were found between VAT and on-break weekdays sleep irregularity on SBP (P interaction=0.034).

CONCLUSIONS

A delayed and an irregular sleep midpoint during school and during free-days, respectively, increase the impact of VAT on elevated blood pressure in adolescents. These data suggest that deviations in the circadian timing of sleep contribute to the increased cardiovascular sequelae associated with obesity and that its distinct metrics require measurement under different entrainment conditions in adolescents.

On the relationship between CT measured abdominal fat parameters and three metabolic risk biomarkers

Introduction: Cardiovascular diseases are the leading cause of morbidity and mortality worldwide, and there is a need for the development of adjacent markers to assess cardiovascular risk. In this study, we examined the relationship between the areas of abdominal fat compartments, as measured by computed tomography (CT)-based planar measurements, and laboratory-validated cardiovascular risk markers.

Methods: Fat distribution was measured on CT scans in 252 patients (M: F = 1.13) who underwent routine abdominal CT, using in-house and commercially available software. The included laboratory parameters were glucose, triglycerides, and the triglycerideglucose index.

Results: The visceral abdominal fat (VAF) area and VAF percentage were lower in females compared to the VAF area and VAF percentage in males, (p=0.001, and p<0.001 respectively). However, the total abdominal fat (TAF) area was not significantly different between genders. Visceral fat and triglyceride levels showed a weakly positive connection for females (r=0.447, p=0.002) but not for males (r=0.229, p=0.09). The glucose levels had a weak correlation with CT calculated abdominal fat parameters, with the strongest statistically significant correlation value being with TAF for females (r=0.331, p=0.003).

Conclusions: Areas of abdominal fat compartments correlate with metabolic parameters in the blood, and in the future, their assessment might be considered when constructing risk scores. Visceral fat content assessment for every abdominal computed tomography procedure might become a surrogate marker for cardio-vascular risk estimation after defining clear cut-off values and image analysis parameters.