Associations between fasting glucose rate-of-change and the missense variant, rs373863828, in an adult Samoan cohort.

BACKGROUND: The A allele of rs373863828 in CREB3 regulatory factor is associated with high Body Mass Index, but lower odds of type 2 diabetes. These associations have been replicated elsewhere, but to date all studies have been cross-sectional. Our aims were (1) to describe the development of type 2 diabetes and change in fasting glucose between 2010 and 2018 among a longitudinal cohort of adult Samoans without type 2 diabetes or who were not using diabetes medications at baseline, and (2) to examine associations between fasting glucose rate-of-change (mmol/L per year) and the A allele of rs373863828. METHODS: We describe and test differences in fasting glucose, the development of type 2 diabetes, body mass index, age, smoking status, physical activity, urbanicity of residence, and household asset scores between 2010 and 2018 among a cohort of n = 401 adult Samoans, selected to have a ~2:2:1 ratio of GG:AG: AA rs373863828 genotypes. Multivariate linear regression was used to test whether fasting glucose rate-of-change was associated with rs373863828 genotype, and other baseline variables. RESULTS: By 2018, fasting glucose and BMI significantly increased among all genotype groups, and a substantial portion of the sample developed type 2 diabetes mellitus. The A allele was associated with a lower fasting glucose rate-of-change (ß = -0.05 mmol/L/year per allele, p = 0.058 among women; ß = -0.004 mmol/L/year per allele, p = 0.863 among men), after accounting for baseline variables. Mean fasting glucose and mean BMI increased over an eight-year period and a substantial number of individuals developed type 2 diabetes by 2018. However, fasting glucose rate-of-change, and type 2 diabetes development was lower among females with AG and AA genotypes. CONCLUSIONS: Further research is needed to understand the effect of the A allele on fasting glucose and type 2 diabetes development. Based on our observations that other risk factors increased over time, we advocate for the continued promotion for diabetes prevention and treatment programming, and the reduction of modifiable risk factors, in this setting.

Isolation of Nuclei from Human Intermuscular Adipose Tissue and Downstream Single-Nuclei RNA Sequencing.

Intermuscular adipose tissue (IMAT) is a relatively understudied adipose depot located between muscle fibers. IMAT content increases with age and BMI and is associated with metabolic and muscle degenerative diseases; however, an understanding of the biological properties of IMAT and its interplay with the surrounding muscle fibers is severely lacking. In recent years, single-cell and nuclei RNA sequencing have provided us with cell type-specific atlases of several human tissues. However, the cellular composition of human IMAT remains largely unexplored due to the inherent challenges of its accessibility from biopsy collection in humans. In addition to the limited amount of tissue collected, the processing of human IMAT is complicated due to its proximity to skeletal muscle tissue and fascia. The lipid-laden nature of the adipocytes makes it incompatible with single-cell isolation. Hence, single nuclei RNA sequencing is optimal for obtaining high-dimensional transcriptomics at single-cell resolution and provides the potential to uncover the biology of this depot, including the exact cellular composition of IMAT. Here, we present a detailed protocol for nuclei isolation and library preparation of frozen human IMAT for single nuclei RNA sequencing. This protocol allows for the profiling of thousands of nuclei using a droplet-based approach, thus providing the capacity to detect rare and low-abundant cell types.

Associations between regional adipose tissue distribution and skeletal muscle bioenergetics in older men and women.

OBJECTIVE: The aim of this study was to examine associations of ectopic adipose tissue (AT) with skeletal muscle (SM) mitochondrial bioenergetics in older adults. METHODS: Cross-sectional data from 829 adults ≥70 years of age were used. Abdominal, subcutaneous, and visceral AT and thigh muscle fat infiltration (MFI) were quantified by magnetic resonance imaging. SM mitochondrial energetics were characterized in vivo (31P-magnetic resonance spectroscopy; ATPmax) and ex vivo (high-resolution respirometry maximal oxidative phosphorylation [OXPHOS]). ActivPal was used to measure physical activity ([PA]; step count). Linear regression adjusted for covariates was applied, with sequential adjustment for BMI and PA. RESULTS: Independent of BMI, total abdominal AT (standardized [Std.] ß = -0.21; R2 = 0.09) and visceral AT (Std. ß = -0.16; R2 = 0.09) were associated with ATPmax (p < 0.01; n = 770) but not following adjustment for PA (p ≥ 0.05; n = 658). Visceral AT (Std. ß = -0.16; R2 = 0.25) and thigh MFI (Std. ß = -0.11; R2 = 0.24) were associated with carbohydrate-supported maximal OXPHOS independent of BMI and PA (p < 0.05; n = 609). Total abdominal AT (Std. ß = -0.19; R2 = 0.24) and visceral AT (Std. ß = -0.17; R2 = 0.24) were associated with fatty acid-supported maximal OXPHOS independent of BMI and PA (p < 0.05; n = 447). CONCLUSIONS: Skeletal MFI and abdominal visceral, but not subcutaneous, AT are inversely associated with SM mitochondrial bioenergetics in older adults independent of BMI. Associations between ectopic AT and in vivo mitochondrial bioenergetics are attenuated by PA.

Interaction of obesity and proteins associated with the NLRP3 inflammasome following mild traumatic brain injury.

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome has been associated with worse outcomes from severe traumatic brain injury (TBI). The NLRP3 inflammasome is also strongly associated with other pro-inflammatory conditions, such as obesity. Little is known about the potential effect of mild TBI (mTBI) on the NLRP3 inflammasome and the extent to which modifying factors, such as obesity, may augment the inflammatory response to mTBI. The purpose of this study was to evaluate the association of NLRP3 inflammasome proteins with obese body mass index (BMI ≥ 30) within 24 h of mTBI after presenting to a level 1 trauma center emergency department. This is a secondary analysis of prospectively enrolled patients with mTBI who presented to the emergency department of one U.S. Level 1 trauma center from 2013 to 2018 (n = 243). A series of regression models were built to evaluate the association of NLRP3 proteins obtained from blood plasma within 24 h of injury and BMI as well as the potential interaction effect of higher BMI with NLRP3 proteins (n = 243). A logistic regression model revealed a significant association between IL-18 (p < 0.001) in mTBI patients with obese BMI compared to mTBI patients with non-obese BMI (< 30). Moderation analyses revealed statistically significant interaction effects between apoptotic speck-like protein (ASC), caspase-1, IL-18, IL-1ß and obese BMI which worsened symptom burden, quality of life, and physical function at 2 weeks and 6 months post-injury. Higher acute concentrations of IL-1ß in the overall cohort predicted higher symptoms at 6-months and worse physical function at 2-weeks and 6-months. Higher acute concentrations of IL-18 in the overall cohort predicted worse physical function at 6-months. In this single center mTBI cohort, obese BMI interacted with higher acute concentrations of NLRP3 inflammasome proteins and worsened short- and long-term clinical outcomes.

Molecular Transducers of Physical Activity Consortium (MoTrPAC): Human Studies Design and Protocol.

Physical activity, including structured exercise, is associated with favorable health-related chronic disease outcomes. While there is evidence of various molecular pathways that affect these responses, a comprehensive molecular map of these molecular responses to exercise has not been developed. The Molecular Transducers of Physical Activity Consortium (MoTrPAC) is a multi-center study designed to isolate the effects of structured exercise training on the molecular mechanisms underlying the health benefits of exercise and physical activity. MoTrPAC contains both a pre-clinical and human component. The details of the human studies component of MoTrPAC that include the design and methods are presented here. The human studies contain both an adult and pediatric component. In the adult component, sedentary participants are randomized to 12 weeks of Control, Endurance Exercise Training, or Resistance Exercise Training with outcomes measures completed before and following the 12 weeks. The adult component also includes recruitment of highly active endurance trained or resistance trained participants who only complete measures once. A similar design is used for the pediatric component; however, only endurance exercise is examined. Phenotyping measures include weight, body composition, vital signs, cardiorespiratory fitness, muscular strength, physical activity and diet, and other questionnaires. Participants also complete an acute rest period (adults only) or exercise session (adults, pediatrics) with collection of biospecimens (blood only for pediatrics) to allow for examination of the molecular responses. The design and methods of MoTrPAC may inform other studies. Moreover, MoTrPAC will provide a repository of data that can be used broadly across the scientific community.

Role of Cardiorespiratory Fitness and Mitochondrial Oxidative Capacity in Reduced Walk Speed of Older Adults With Diabetes.

Cardiorespiratory fitness and mitochondrial oxidative capacity are associated with reduced walking speed in older adults, but their impact on walking speed in older adults with diabetes has not been clearly defined. We examined differences in cardiorespiratory fitness and skeletal muscle mitochondrial oxidative capacity between older adults with and without diabetes, as well as determined their relative contribution to slower walking speed in older adults with diabetes. Participants with diabetes (n = 159) had lower cardiorespiratory fitness and mitochondrial respiration in permeabilized fiber bundles compared with those without diabetes (n = 717), following adjustments for covariates including BMI, chronic comorbid health conditions, and physical activity. Four-meter and 400-m walking speeds were slower in those with diabetes. Mitochondrial oxidative capacity alone or combined with cardiorespiratory fitness mediated ∼20-70% of the difference in walking speed between older adults with and without diabetes. Additional adjustments for BMI and comorbidities further explained the group differences in walking speed. Cardiorespiratory fitness and skeletal muscle mitochondrial oxidative capacity contribute to slower walking speeds in older adults with diabetes.

Percutaneous biopsies of skeletal muscle and adipose tissue in individuals older than 70: methods and outcomes in the Study of Muscle, Mobility and Aging (SOMMA).

Biopsies of muscle and adipose tissue (AT) are useful tools to gain insights into the aging processes in these tissues. However, they are invasive procedures and their risk/benefit profile in older adults can be altered by sarcopenia, frailty, poor healing, and multimorbidity. Their success rates, safety, and tolerability in a geriatric population have not been reported in detail. Investigators in the Study of Muscle, Mobility, and Aging (SOMMA) performed biopsies of muscle and AT in older adults and prospectively collected data on biopsy success rates, safety, and tolerability. We report here the methods and outcomes of these two procedures. In total, 861 participants (aged 70-94) underwent percutaneous biopsies of the Vastus lateralis muscle with a Bergstrom needle. A subset (n = 241) also underwent percutaneous biopsies of the abdominal subcutaneous AT with the tumescent liposuction technique. Success rate was assessed by the percentage of biopsies yielding adequate specimens for analyses; tolerability by pain scores; and safety by frequency of adverse events. All data were prospectively collected. The overall muscle biopsy success rate was 97.1% and was modestly lower in women. The AT biopsy success rate was 95.9% and slightly lower in men. Minimal or no pain was reported in 68% of muscle biopsies and in 83% of AT biopsies. Adverse events occurred in 2.67% of muscle biopsies and 4.15% of AT biopsies. None was serious. In older adults, percutaneous muscle biopsies and abdominal subcutaneous AT biopsies have an excellent safety profile, often achieve adequate tissue yields for analyses, and are well tolerated.

Leveraging inter-individual transcriptional correlation structure to infer discrete signaling mechanisms across metabolic tissues.

Inter-organ communication is a vital process to maintain physiologic homeostasis, and its dysregulation contributes to many human diseases. Given that circulating bioactive factors are stable in serum, occur naturally, and are easily assayed from blood, they present obvious focal molecules for therapeutic intervention and biomarker development. Recently, studies have shown that secreted proteins mediating inter-tissue signaling could be identified by 'brute force' surveys of all genes within RNA-sequencing measures across tissues within a population. Expanding on this intuition, we reasoned that parallel strategies could be used to understand how individual genes mediate signaling across metabolic tissues through correlative analyses of gene variation between individuals. Thus, comparison of quantitative levels of gene expression relationships between organs in a population could aid in understanding cross-organ signaling. Here, we surveyed gene-gene correlation structure across 18 metabolic tissues in 310 human individuals and 7 tissues in 103 diverse strains of mice fed a normal chow or high-fat/high-sucrose (HFHS) diet. Variation of genes such as FGF21, ADIPOQ, GCG, and IL6 showed enrichments which recapitulate experimental observations. Further, similar analyses were applied to explore both within-tissue signaling mechanisms (liver PCSK9) and genes encoding enzymes producing metabolites (adipose PNPLA2), where inter-individual correlation structure aligned with known roles for these critical metabolic pathways. Examination of sex hormone receptor correlations in mice highlighted the difference of tissue-specific variation in relationships with metabolic traits. We refer to this resource as gene-derived correlations across tissues (GD-CAT) where all tools and data are built into a web portal enabling users to perform these analyses without a single line of code (gdcat.org). This resource enables querying of any gene in any tissue to find correlated patterns of genes, cell types, pathways, and network architectures across metabolic organs.

Acute activation of adipocyte lipolysis reveals dynamic lipid remodeling of the hepatic lipidome.

Adipose tissue is the site of long-term energy storage. During the fasting state, exercise, and cold exposure, the white adipose tissue mobilizes energy for peripheral tissues through lipolysis. The mobilization of lipids from white adipose tissue to the liver can lead to excess triglyceride accumulation and fatty liver disease. Although the white adipose tissue is known to release free fatty acids, a comprehensive analysis of lipids mobilized from white adipocytes in vivo has not been completed. In these studies, we provide a comprehensive quantitative analysis of the adipocyte-secreted lipidome and show that there is interorgan crosstalk with liver. Our analysis identifies multiple lipid classes released by adipocytes in response to activation of lipolysis. Time-dependent analysis of the serum lipidome showed that free fatty acids increase within 30 min of ß3-adrenergic receptor activation and subsequently decrease, followed by a rise in serum triglycerides, liver triglycerides, and several ceramide species. The triglyceride composition of liver is enriched for linoleic acid despite higher concentrations of palmitate in the blood. To further validate that these findings were a specific consequence of lipolysis, we generated mice with conditional deletion of adipose tissue triglyceride lipase exclusively in adipocytes. This loss of in vivo adipocyte lipolysis prevented the rise in serum free fatty acids and hepatic triglycerides. Furthermore, conditioned media from adipocytes promotes lipid remodeling in hepatocytes with concomitant changes in genes/pathways mediating lipid utilization. Together, these data highlight critical role of adipocyte lipolysis in interorgan crosstalk between adipocytes and liver.

Association between age at menarche and cardiometabolic risk among Samoan adults.

OBJECTIVES: Recent studies suggest that early menarche may increase cardiometabolic morbidity and mortality. Yet few studies have examined this association in the Pacific Islands, where obesity prevalence is among the highest globally. We sought to examine associations between age at menarche and cardiometabolic risk in Samoa. METHODS: Participants were from the Soifua Manuia study (n = 285, age 32-72 years) conducted in Samoa from 2017 to 2019. Logistic regressions were conducted to estimate odds of obesity, hypertension, diabetes, dyslipidemia, and metabolic syndrome per one-year increase in age at menarche. Linear regressions were conducted to examine associations between age at menarche and continuous measures of adiposity, blood pressure, insulin resistance, and serum lipids. RESULTS: Median age at menarche was 14 years (IQR = 2). After controlling for relevant covariates, each one-year increase in age at menarche was associated with a 15% decrease (OR = 0.85, 95% CI: 0.72-1.01, p = .067) in odds of hypertension, but a 21% increase (OR = 1.21, 95% CI: 1.01-1.45, p = .044) in odds of diabetes and 18% increase (OR = 1.18, 95% CI: 0.98-1.42, p = .081) in odds of high total cholesterol. Each additional year in age at menarche was associated with a 1.60 ± 0.52 kg (p = .002) decrease in lean mass and 1.56 ± 0.51 kg (p = .003) decrease in fat-free mass. CONCLUSIONS: Associations between age at menarche and cardiometabolic risk may be population-specific and are likely influenced by both current and historical nutritional and epidemiological contexts. Prospective studies are needed to clarify the role of childhood adiposity and other early life exposures on age at menarche and subsequent cardiometabolic risk.

Role of Cardiorespiratory Fitness and Mitochondrial Energetics in Reduced Walk Speed of Older Adults with Diabetes in the Study of Muscle, Mobility and Aging (SOMMA).

Rationale: Cardiorespiratory fitness and mitochondrial energetics are associated with reduced walking speed in older adults. The impact of cardiorespiratory fitness and mitochondrial energetics on walking speed in older adults with diabetes has not been clearly defined. Objective: To examine differences in cardiorespiratory fitness and skeletal muscle mitochondrial energetics between older adults with and without diabetes. We also assessed the contribution of cardiorespiratory fitness and skeletal muscle mitochondrial energetics to slower walking speed in older adults with diabetes. Findings: Participants with diabetes had lower cardiorespiratory fitness and mitochondrial energetics when compared to those without diabetes, following adjustments for covariates including BMI, chronic comorbid health conditions, and physical activity. 4-m and 400-m walking speeds were slower in those with diabetes. Mitochondrial oxidative capacity alone or combined with cardiorespiratory fitness mediated ∼20-70% of the difference in walk speed between older adults with and without diabetes. Further adjustments of BMI and co-morbidities further explained the group differences in walk speed. Conclusions: Skeletal muscle mitochondrial energetics and cardiorespiratory fitness contribute to slower walking speeds in older adults with diabetes. Cardiorespiratory fitness and mitochondrial energetics may be therapeutic targets to maintain or improve mobility in older adults with diabetes. ARTICLE HIGHLIGHTS: Why did we undertake this study? To determine if mitochondrial energetics and cardiorespiratory fitness contribute to slower walking speed in older adults with diabetes. What is the specific question(s) we wanted to answer? Are mitochondrial energetics and cardiorespiratory fitness in older adults with diabetes lower than those without diabetes? How does mitochondrial energetics and cardiorespiratory fitness impact walking speed in older adults with diabetes? What did we find? Mitochondrial energetics and cardiorespiratory fitness were lower in older adults with diabetes compared to those without diabetes, and energetics, and cardiorespiratory fitness, contributed to slower walking speed in those with diabetes. What are the implications of our findings? Cardiorespiratory fitness and mitochondrial energetics may be key therapeutic targets to maintain or improve mobility in older adults with diabetes.

Associations between regional adipose tissue distribution and skeletal muscle bioenergetics in older men and women.

Objective: Examine the association of ectopic adipose tissue (AT) with skeletal muscle (SM) mitochondrial bioenergetics in older adults. Methods: Cross-sectional data from 829 older adults ≥70 years was used. Total abdominal, subcutaneous, and visceral AT; and thigh muscle fat infiltration (MFI) was quantified by MRI. SM mitochondrial energetics were characterized using in vivo 31 P-MRS (ATP max ) and ex vivo high-resolution respirometry (maximal oxidative phosphorylation (OXPHOS)). ActivPal was used to measure PA (step count). Linear regression models adjusted for covariates were applied, with sequential adjustment for BMI and PA. Results: Independent of BMI, total abdominal (standardized (Std.) ß=-0.21; R 2 =0.09) and visceral AT (Std. ß=-0.16; R 2 =0.09) were associated with ATP max ( p <0.01), but not after further adjustment for PA (p≥0.05). Visceral AT (Std. ß=-0.16; R 2 =0.25) and thigh MFI (Std. ß=-0.11; R 2 =0.24) were negatively associated with carbohydrate-supported maximal OXPHOS independent of BMI and PA ( p <0.05). Total abdominal AT (Std. ß=-0.19; R 2 =0.24) and visceral AT (Std. ß=-0.17; R 2 =0.24) were associated with fatty acid-supported maximal OXPHOS independent of BMI and PA (p<0.05). Conclusions: Skeletal MFI and abdominal visceral, but not subcutaneous AT, are inversely associated with SM mitochondrial bioenergetics in older adults independent of BMI. Associations between ectopic AT and in vivo mitochondrial bioenergetics are attenuated by PA.

Medical management of hypertriglyceridemia in pancreatitis.

PURPOSE OF REVIEW: Hypertriglyceridemia-induced acute pancreatitis (HTG-AP) should be considered in all cases of acute pancreatitis and triglyceride levels measured early, so that appropriate early and long-term treatment can be initiated. RECENT FINDINGS: In most cases of HTG-AP, conservative management (nothing by mouth, intravenous fluid resuscitation and analgesia) is sufficient to achieve triglyceride levels less than 500 mg/dl. Intravenous insulin and plasmapheresis are sometimes used, although prospective studies showing clinical benefits are lacking. Pharmacological management of hypertriglyceridemia (HTG) should start early and target triglyceride levels of less than 500 mg/dl to reduce the risk or recurrent acute pancreatitis. In addition to currently used fenofibrate and omega-3 fatty acids, several novel agents are being studied for long-term treatment of HTG. These emerging therapies focus mainly on modifying the action of lipoprotein lipase (LPL) through inhibition of apolipoprotein CIII and angiopoietin-like protein 3. Dietary modifications and avoidance of secondary factors that worsen triglyceride levels should also be pursued. In some cases of HTG-AP, genetic testing may help personalize management and improve outcomes. SUMMARY: Patients with HTG-AP require acute and long-term management of HTG with the goal of reducing and maintaining triglyceride levels to less than 500 mg/dl.

Evinacumab in severe hypertriglyceridemia with or without lipoprotein lipase pathway mutations: a phase 2 randomized trial.

Severe hypertriglyceridemia (sHTG) is an established risk factor for acute pancreatitis. Current therapeutic approaches for sHTG are often insufficient to reduce triglycerides and prevent acute pancreatitis. This phase 2 trial ( NCT03452228 ) evaluated evinacumab (angiopoietin-like 3 inhibitor) in three cohorts of patients with sHTG: cohort 1, familial chylomicronemia syndrome with bi-allelic loss-of-function lipoprotein lipase (LPL) pathway mutations (n = 17); cohort 2, multifactorial chylomicronemia syndrome with heterozygous loss-of-function LPL pathway mutations (n = 15); and cohort 3, multifactorial chylomicronemia syndrome without LPL pathway mutations (n = 19). Fifty-one patients (males, n = 27; females, n = 24) with a history of hospitalization for acute pancreatitis were randomized 2:1 to intravenous evinacumab 15 mg kg-1 or placebo every 4 weeks over a 12-week double-blind treatment period, followed by a 12-week single-blind treatment period. The primary end point was the mean percent reduction in triglycerides from baseline after 12 weeks of evinacumab exposure in cohort 3. Evinacumab reduced triglycerides in cohort 3 by a mean (s.e.m.) of -27.1% (37.4) (95% confidence interval -71.2 to 84.6), but the prespecified primary end point was not met. No notable differences in adverse events between evinacumab and placebo treatment groups were seen during the double-blind treatment period. Although the primary end point of a reduction in triglycerides did not meet the prespecified significance level, the observed safety and changes in lipid and lipoprotein levels support the further evaluation of evinacumab in larger trials of patients with sHTG. Trial registration number: ClinicalTrials.gov NCT03452228 .

A stop-gain variant in BTNL9 is associated with atherogenic lipid profiles.

Current understanding of lipid genetics has come mainly from studies in European-ancestry populations; limited effort has focused on Polynesian populations, whose unique population history and high prevalence of dyslipidemia may provide insight into the biological foundations of variation in lipid levels. Here, we performed an association study to fine map a suggestive association on 5q35 with high-density lipoprotein cholesterol (HDL-C) seen in Micronesian and Polynesian populations. Fine-mapping analyses in a cohort of 2,851 Samoan adults highlighted an association between a stop-gain variant (rs200884524; c.652C>T, p.R218∗; posterior probability = 0.9987) in BTNL9 and both lower HDL-C and greater triglycerides (TGs). Meta-analysis across this and several other cohorts of Polynesian ancestry from Samoa, American Samoa, and Aotearoa New Zealand confirmed the presence of this association (ßHDL-C = -1.60 mg/dL, p HDL-C = 7.63 × 10-10; ßTG = 12.00 mg/dL, p TG = 3.82 × 10-7). While this variant appears to be Polynesian specific, there is also evidence of association from other multiancestry analyses in this region. This work provides evidence of a previously unexplored contributor to the genetic architecture of lipid levels and underscores the importance of genetic analyses in understudied populations.

Multivariate analysis of a missense variant in CREBRF reveals associations with measures of adiposity in people of Polynesian ancestries.

The minor allele of rs373863828, a missense variant in CREB3 Regulatory Factor, is associated with several cardiometabolic phenotypes in Polynesian peoples. To better understand the variant, we tested the association of rs373863828 with a panel of correlated phenotypes (body mass index [BMI], weight, height, HDL cholesterol, triglycerides, and total cholesterol) using multivariate Bayesian association and network analyses in a Samoa cohort (n = 1632), Aotearoa New Zealand cohort (n = 1419), and combined cohort (n = 2976). An expanded set of phenotypes (adding estimated fat and fat-free mass, abdominal circumference, hip circumference, and abdominal-hip ratio) was tested in the Samoa cohort (n = 1496). In the Samoa cohort, we observed significant associations (log10 Bayes Factor [BF] ≥ 5.0) between rs373863828 and the overall phenotype panel (8.81), weight (8.30), and BMI (6.42). In the Aotearoa New Zealand cohort, we observed suggestive associations (1.5 < log10 BF < 5) between rs373863828 and the overall phenotype panel (4.60), weight (3.27), and BMI (1.80). In the combined cohort, we observed concordant signals with larger log10 BFs. In the Samoa-specific expanded phenotype analyses, we also observed significant associations between rs373863828 and fat mass (5.65), abdominal circumference (5.34), and hip circumference (5.09). Bayesian networks provided evidence for a direct association of rs373863828 with weight and indirect associations with height and BMI.

The protective effect of rs373863828 on type 2 diabetes does not operate through a body composition pathway in adult Samoans.

OBJECTIVE: The aim of this study was to understand whether the paradoxical association of missense variant rs373863828 in CREB3 regulatory factor (CREBRF) with higher BMI but lower odds of diabetes is explained by either metabolically favorable body fat distribution or greater fat-free mass. METHODS: This study explored the association of the minor allele with dual-energy x-ray absorptiometry-derived body composition in n = 421 Samoans and used path analysis to examine the mediating role of fat and fat-free mass on the relationship between rs373863828 and fasting glucose. RESULTS: Among females, the rs373863828 minor A allele was associated with greater BMI. There was no association of genotype with percent body fat, visceral adiposity, or fat distribution in either sex. In both females and males, lean mass was greater with each A allele: 2.16 kg/copy (p = 0.0001) and 1.73 kg/copy (p = 0.02), respectively. Path analysis showed a direct negative effect of rs373863828 genotype on fasting glucose (p = 0.004) consistent with previous findings, but also an indirect positive effect on fasting glucose operating through fat-free mass (p = 0.027). CONCLUSIONS: The protective effect of rs373863828 in CREBRF, common among Pacific Islanders, on type 2 diabetes does not operate through body composition. Rather, the variant's effects on body size/composition and fasting glucose likely operate via different, tissue-specific mechanisms.

Effect of physical activity in a weight loss program on circulating total ANGPTL8 concentrations in northern Americans with obesity: A prospective randomized controlled trial.

BACKGROUND AND AIMS: The primary goals of this study were to clarify 1) the effect of weight loss by lifestyle intervention on circulating total angiopoietin-like protein 8 (ANGPTL8), and 2) the role of physical activity on serum total ANGPTL8 in northern Americans with obesity but without diabetes. METHODS AND RESULTS: A total of 130 subjects with body mass index (BMI) â‰§ 35 kg/m2 but without diabetes were recruited, and 121 subjects completed a weight loss program for data analysis. Abdominal adipose tissue was determined by non-contrast computed tomography (CT). Serum total ANGPTL8 was higher in the group with obesity than in the lean control group. Serum total ANGPTL8 was positively correlated with waist circumference (WC), BMI, fasting insulin, HOMA-IR, HOMA-B, QUICKI, hs-CRP, IL-6, and leptin. Serum total ANGPTL8 did not significantly differ between the two intervention groups at baseline, and it was significantly lower after weight loss, with comparable changes with diet only and diet plus physical activity. CONCLUSION: Among northern Americans with obesity but without diabetes, a lifestyle modification resulted in significant reduction of circulating total ANGPTL8 concentrations in a 6-month weight-loss period. Although addition of physical activity resulted in greater total and liver fat loss, it did not promote further significant decline of serum total ANGPTL8 beyond diet alone.

Pharmacological inhibition of adipose tissue adipose triglyceride lipase by Atglistatin prevents catecholamine-induced myocardial damage.

AIMS: Heart failure (HF) is characterized by an overactivation of ß-adrenergic signalling that directly contributes to impairment of myocardial function. Moreover, ß-adrenergic overactivation induces adipose tissue lipolysis, which may further worsen the development of HF. Recently, we demonstrated that adipose tissue-specific deletion of adipose triglyceride lipase (ATGL) prevents pressure-mediated HF in mice. In this study, we investigated the cardioprotective effects of a new pharmacological inhibitor of ATGL, Atglistatin, predominantly targeting ATGL in adipose tissue, on catecholamine-induced cardiac damage. METHODS AND RESULTS: Male 129/Sv mice received repeated injections of isoproterenol (ISO, 25 mg/kg BW) to induce cardiac damage. Five days prior to ISO application, oral Atglistatin (2 mmol/kg diet) or control treatment was started. Two and twelve days after the last ISO injection cardiac function was analysed by echocardiography. The myocardial deformation was evaluated using speckle-tracking-technique. Twelve days after the last ISO injection, echocardiographic analysis revealed a markedly impaired global longitudinal strain, which was significantly improved by the application of Atglistatin. No changes in ejection fraction were observed. Further studies included histological-, WB-, and RT-qPCR-based analysis of cardiac tissue, followed by cell culture experiments and mass spectrometry-based lipidome analysis. ISO application induced subendocardial fibrosis and a profound pro-apoptotic cardiac response, as demonstrated using an apoptosis-specific gene expression-array. Atglistatin treatment led to a dramatic reduction of these pro-fibrotic and pro-apoptotic processes. We then identified a specific set of fatty acids (FAs) liberated from adipocytes under ISO stimulation (palmitic acid, palmitoleic acid, and oleic acid), which induced pro-apoptotic effects in cardiomyocytes. Atglistatin significantly blocked this adipocytic FA secretion. CONCLUSION: This study demonstrates cardioprotective effects of Atglistatin in a mouse model of catecholamine-induced cardiac damage/dysfunction, involving anti-apoptotic and anti-fibrotic actions. Notably, beneficial cardioprotective effects of Atglistatin are likely mediated by non-cardiac actions, supporting the concept that pharmacological targeting of adipose tissue may provide an effective way to treat cardiac dysfunction.