Insights into the multifactorial causation of obesity by integrated genetic and epigenetic analysis

Epigenome-wide association study meta-analysis of BMI in African Americans

Despite considerable advances in identifying risk factors for obesity development, there remains substantial gaps in our knowledge about its etiology. Variation in obesity (defined by BMI) is thought to be due in part to heritable factors; however, obesity-associated genetic variants only account for a small portion of heritability. Epigenetic regulation, defined by genetic and/or environmental factors with changes in gene expression, may account for some of this "missing heritability". Epigenetic studies of obesity have largely been conducted in populations of European ancestry, despite the disproportionate burden of obesity in African Americans (AAs). To address race/ethnic (RE)-differences in obesity, we conducted a BMI epigenome-wide association study (EWAS) meta-analysis using AA participants from the Jackson Heart Study (JHS, n=1604) and the Multi-Ethnic Study of Atherosclerosis (MESA, n=179). Analyses using a linear regression model with methylation as the outcome and continuous BMI as the predictor were stratified by study and sex, then meta-analyzed. There were 208 methylation sites (CpGs) that reached epigenome-wide significance (p< 8.72×10 -8 ); 151 of these were novel. Of the novel CpGs, 29 CpGs were available for replication testing in a separate sample of AA and 20 replicated. Differentially methylated region (DMR) analysis resulted in 54 DMRs significantly associated with BMI. Several regions are proximal to, or include, genes previously associated with obesity traits (e.g., SOCS3, ABCG1 , and TGFB1 ) in GWAS. Gene and trait enrichment and pathway analysis showed enrichment for genes in immune system and inflammation related pathways (e.g., the IL-6/JAK/STAT pathway). In conclusion, EWAS of BMI in AAs replicated previously known associations identified in European ancestry and multi-ethnic EWAS and identified novel obesity-associated CpGs.

Using stereotype violation to shift causal understanding and attitudes about weight

OBJECTIVE

We evaluated an approach to weight stigma reduction involving the provision of an exemplar inconsistent with belief systems underlying weight bias. Specifically, that people with higher weight eat unhealthy, high-calorie diets, and people with lower weight eat healthy, low-calorie diets. Providing exemplars that violate the stereotype's assumptions may lead to a change in beliefs, stereotypes, and ultimately, stigma.

METHODS

In an experimental, web-based study, 682 US-based participants were randomized to read narrative vignettes about a fictional middle-aged woman portrayed as either having stable, high body weight, or stable, low body weight, and as eating a long-term diet that was either high- or low- in calorie-dense foods. Two stereotype violation conditions involved a woman with higher weight who maintains a low-calorie diet (HWLC) and a woman with lower weight who maintains a high-calorie diet (LWHC).

RESULTS

For the HWLC exemplar, results were consistent with stereotype change processes including heightened genetic causal attributions, reduced lifestyle attributions, and more positive attitudes toward the exemplar and "women with obesity" in general. Response to the LWHC exemplar was more uneven.

CONCLUSIONS

Findings have implications in the understanding of judgments that people make about individuals based on their body size and dietary habits and suggests a new route for interventions that address weight stigma reduction.

Host Genetics Background Affects Intestinal Cancer Development Associated with High-Fat Diet-Induced Obesity and Type 2 Diabetes

BACKGROUND

Obesity and type 2 diabetes (T2D) promote inflammation, increasing the risk of colorectal cancer (CRC). High-fat diet (HFD)-induced obesity is key to these diseases through biological mechanisms. This study examined the impact of genetic background on the multimorbidity of intestinal cancer, T2D, and inflammation due to HFD-induced obesity.

METHODS

A cohort of 357 Collaborative Cross (CC) mice from 15 lines was fed either a control chow diet (CHD) or HFD for 12 weeks. Body weight was tracked biweekly, and blood glucose was assessed at weeks 6 and 12 via intraperitoneal glucose tolerance tests (IPGTT). At the study's endpoint, intestinal polyps were counted, and cytokine profiles were analyzed to evaluate the inflammatory response.

RESULTS

HFD significantly increased blood glucose levels and body weight, with males showing higher susceptibility to T2D and obesity. Genetic variation across CC lines influenced glucose metabolism, body weight, and polyp development. Mice on HFD developed more intestinal polyps, with males showing higher counts than females. Cytokine analysis revealed diet-induced variations in pro-inflammatory markers like IL-6, IL-17A, and TNF-α, differing by genetic background and sex.

CONCLUSIONS

Host genetics plays a crucial role in susceptibility to HFD-induced obesity, T2D, CRC, and inflammation. Genetic differences across CC lines contributed to variability in disease outcomes, providing insight into the genetic underpinnings of multimorbidity. This study supports gene-mapping efforts to develop personalized prevention and treatment strategies for these diseases.

Body Size Measurements Grouped Independently of Common Clinical Measures of Metabolic Health: An Exploratory Factor Analysis

BACKGROUND

Obesity is commonly aggregated with indices of metabolic health. Proponents of body positivity approaches question whether body size is a determinant of health and well-being. Our objective was to conduct an exploratory factor analysis (EFA) to determine if body size measurements factor load with or independent of metabolic health measures.

METHODS

The EFA was conducted on n= 249 adults using baseline data from four weight loss trials (Sample 1: n = 40; Sample 2: n = 52; Sample 3: n = 53; Sample 4: n = 104). An EFA of nine items (systolic blood pressure [SBP], diastolic blood pressure [DBP], hemoglobin A1c [HbA1c], HDL-cholesterol [HDL], LDL-cholesterol [LDL], total cholesterol [TC], body mass index [BMI], body fat percent BF%], and waist circumference [WC]) was conducted with oblique rotation.

RESULTS

Three factors were retained, which produced a model explaining 87.5% of the variance. Six items loaded strongly (>0.8) under three components and were selected for retention (Factor 1: LDL and TC; Factor 2: BMI and WC; Factor 3: SBP and DBP).

CONCLUSION

Body size measures loaded separately from measures of metabolic health and metabolic health were further split into lipid- and blood pressure-focused factors. These results support weight-neutral interventions to improve overall health and well-being.

Antiobesity and Hypolipidemic Potential of Nitraria retusa Extract in Overweight/Obese Women: A Randomized, Double-Blind, Placebo-Controlled Pilot Study

This study aimed to assess the efficacy of Nitraria retusa extract (NRE) in reducing weight, body mass index (BMI), body fat composition (BF), and anthropometric parameters among overweight/obese women, comparing the results with those of a placebo group. Overweight/obese individuals participated in a 12-week, double-blind, randomized, placebo-controlled trial. Body weight, BMI, body composition, and anthropometric parameters were assessed. Additionally, lipid profile and safety evaluation parameters were evaluated. Compared to the placebo group, the NRE group exhibited a mean weight loss difference of 2.27 kg (p < 0.001) at the trial's conclusion. Interestingly, the most significant weight reduction, amounting to 3.34 kg ± 0.93, was observed in younger participants with a BMI > 30.0. Similarly, BMI and BF% significantly decreased in the NRE group, contrary to the placebo group (p = 0.008 and p = 0.005, respectively). The percentage of body water (BW) (p = 0.006) as well as the ratio of LBM/BF (p = 0.039) showed a significant increase after the NRE intervention compared to the placebo. After age adjustment, all variables, except LBM/BF, retained statistical significance. Additionally, all anthropometric parameters were significantly reduced only in the NRE group. Most importantly, a significant reduction in Triglyceride (TG) levels in the NRE group was revealed, in contrast to the placebo group (p = 0.011), and the significance was still observed after age adjustment (p = 0.016). No side effects or adverse changes in kidney and liver function tests were observed in both groups. In conclusion, NRE demonstrated potent antiobesity effects, suggesting that NRE supplementation may represent an effective alternative for treating obesity compared to antiobesity synthetic drugs.

Combination Therapy: A New Tool for the Management of Obesity

Obesity is a chronic lifestyle issue with devastating results. Behavioral changes are one of the initial lines of management strategies for obesity, but they are not very efficient management strategies. Many people also use surgical intervention to maintain a healthy weight, now considered to be the most common and effective obesity management. Chemically synthesized medicines fill the gap between lifestyle interventions and minimally invasive surgical management of obesity. The most common issue associated with monotherapy without side effects is its moderate effectiveness and higher dose requirement. Combination therapy is already used for many serious and complicated disease treatments and management and has shown efficacy as well. Generally, we use two or more medicines with different mechanisms of action for a better effect. The commonly used combination therapy for obesity management includes low-dose phentermine and prolonged and slow-releasing mechanism topiramate; naltrexone, and bupropion. Phentermine with inhibitors of Na-glucose cotransporter-2 or glucagon-like peptide-1 (GLP-1) agonists with gastric hormone or Na-glucose cotransporter-2 are two more viable combo therapy. This combination strategy aims to achieve success in bariatric surgery and the scientific community is working in this direction.

Burden of diseases attributable to excess body weight in the Middle East and North Africa region, 1990-2019

High body mass index (BMI), or excess body weight (EBW), represents a significant risk factor for a range of diseases, including cardiovascular diseases and cancers. The study sought to determine the burden of diseases attributable to EBW in the Middle East and North Africa (MENA) region from 1990 and 2019. The analysis also included an exploration of this burden by age, sex, underlying cause, and sociodemographic index (SDI). We utilized publicly available data from the Global Burden of Disease (GBD) study 2019 to identify the deaths and disability-adjusted life-years (DALYs) of diseases associated with EBW in MENA, spanning the period from 1990 to 2019. The GBD estimated the mean BMI and the prevalence of EBW using hierarchical mixed-effects regression, followed by spatiotemporal Gaussian process regression to determine the most accurate BMI distribution through comparison with actual data. In 2019, there were an estimated 538.4 thousand deaths (95% UI 369.9-712.3) and 17.9 million DALYs (12.9-23.1) attributable to EBW in the region. The DALYs attributable to EBW were higher in men (9.3 million [6.5-12.4]) than in women (8.5 million [6.4-10.8]). The age-standardized death and DALY rates for the diseases associated with EBW increased by 5.1% (- 9.0-25.9) and 8.3% (- 6.5-28.8), respectively, during the study period which was not significant. Egypt had the highest age-standardized mortality rate due to EBW (217.7 [140.0, 307.8]), while Yemen (88.6 [45.9, 143.5]) had the lowest. In 2019, the highest number of DALYs occurred among individuals aged 60 to 64 years old. Furthermore, we found a positive association between a nation's SDI and the age-standardized DALY rate linked to EBW. Cardiovascular disease emerged as the leading contributor to the EBW burden in MENA. The disease burden attributable to EBW showed a non-significant increase in MENA from 1990 to 2019.

Metabolic syndrome: Nutri-epigenetic cause or consequence?

Metabolic syndrome is a cluster of conditions that results from the interplay of genetic and environmental factors, which increase the comorbidity risk of obesity, hyperglycemia, dyslipidemia, arterial hypertension, stroke, and cardiovascular disease. In this article, we review various high-impact studies which link epigenetics with metabolic syndrome by comparing each study population, methylation effects, and strengths and weaknesses of each research. We also discuss world statistical data on metabolic syndrome incidence in developing countries where the metabolic syndrome is common condition that has significant public health implications.

Use of behavioural change taxonomies in systematic reviews and meta-analyses regarding obesity management

We investigated the prevalence of behavioural change taxonomies in systematic reviews and meta-analyses related to obesity management. In addition, we analysed the funding sources, author conflicts of interest statements, risk of bias, and favorability of the results in such studies to determine if there was a relationship between methodological quality and taxonomy use. We searched several databases including MEDLINE, Epistemonikos, Cochrane EDSR, Pubmed and Embase for systematic reviews and meta-analyses regarding the behavioural treatment of obesity. Screening and data extraction was performed in a masked, duplicate fashion. We performed statistical analyses to determine any significant association between use of taxonomy and study characteristics. Fifteen (of 186; 8.06%) systematic reviews used a taxonomy-nine used the BCTTv1, three used OXFAB, two used the CALO-RE and one used "Taxonomy of choice architecture techniques." Most interventions that referenced a taxonomy were self-mediated (6/60, 10%). Behavioural change taxonomies were mentioned in 10 (of 87, 11.49%) studies with a public funding source. Of the studies with favourable results, 14 studies (of 181, 7.73%) referred to a taxonomy. We found no statistically significant relationships between use of taxonomy and study characteristics. We found that systematic reviews regarding the management of obesity rarely mention a behavioural change taxonomy. Given the global burden of obesity, it is crucial that behavioural change techniques are reproducible and translatable. We recommend that researchers look further into how taxonomies affect the quality and reproducibility of behavioural interventions in an effort to improve patient outcomes.

The association of self-efficacy and coping strategies with body mass index is mediated by eating behaviors and dietary intake among young females: A structural-equation modeling approach

Globally, around three billion people are either under- or overweight. Speculating the different roles of psychological factors in body weight between over- and underweight people, it was first hypothesized that whether or not the effects of self-efficacy and coping strategies on body mass index (BMI) is different between these two groups. We secondly predicted that their association is mediated by nutritional factors. Therefore, the present cross-sectional study was conducted to model the impact of self-efficacy and coping strategies on eating behaviors, dietary intake and BMI, using structural equation modeling in two BMI groups: low-to-normal-BMI (LBMI: BMI<21.75 kg/m2) and normal-to-high-BMI (HBMI: 21.75 kg/m2 ≤ BMI). Female participants (N = 250, aged ≥18) were included using convenience sampling method and data of self-efficacy, coping strategies, eating behaviors and dietary intake were collected via questionnaires. The model fit was evaluated and confirmed by fit indices. The analysis revealed in both groups the participants tended to adopt emotion-focused coping strategy (EFCS) more than problem-focused coping strategy (PFCS) (mean score: 61.82 (7.96) vs 49.21 (6.73)). The HBMI group tended to use EFCS more than the LBMI group (P<0.001). In the LBMI group, self-efficacy, PFCS and EFCS had positive effects on BMI. Only the direct effect of self-efficacy (β = 0.314, P<0.001) and the indirect effects of PFCS and EFCS (through increasing unhealthy eating behaviors; β = 0.127, P<0.01, β = 0.095, P<0.05, respectively) were significant. In the HBMI group, self-efficacy had negative effect on BMI (both directly (β = -0.229, P<0.05) and indirectly (β = -0.103, P<0.05) by decreasing unhealthy eating behaviors). PFCS had no effect and EFCS had an indirect, positive effect on BMI (through increasing unhealthy eating behaviors, β = 0.162, P = 0.001). In conclusion, these findings suggest that improving self-efficacy and coping-strategies seems helpful to have a healthy BMI in both BMI groups and further interventions to reduce EFCS should be limited to overweight people.

Molecular aspects of COVID-19 and its relationship with obesity and physical activity: a narrative review

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 has several mechanisms of action related to inflammatory responses, especially in individuals diagnosed with obesity. This hyperinflammatory clinical profile resulting from the association between obesity and coronavirus disease 2019 (COVID-19) may be attenuated by regular physical activity.

OBJECTIVE

The aim of this study was to review the evidence on the consequences of physical inactivity and physical activity on COVID-19 in patients with obesity.

DESIGN AND SETTING

Narrative review at the Bahiana School of Medicine and Public Health in Salvador, Brazil.

METHODS

We searched evidence on the association of COVID-19 with physical activity and obesity using the following keywords: "covid-19," "physical activity," and "obesity". The databases used were MEDLINE (PubMed), ScienceDirect, and Virtual Health Library. Studies published from 2019 to 2021 and available in Portuguese, English, and Spanish were included. The final search was conducted on September 26, 2021.

RESULTS

We identified 661 studies in the database, among which 71 were considered for inclusion in the narrative review of the molecular aspects of COVID-19 and its relationship with physical activity and obesity.

CONCLUSION

This literature review enabled the perception of the relationship between the molecular mechanisms of COVID-19 and obesity. Regular physical activity had various benefits for the inflammatory condition of the studied population, highlighting moderate-intensity.

Obesity and Overweight Among Children With Medical Complexity

OBJECTIVES

To assess the prevalence of overweight or obesity among children with medical complexity (CMC), compared with children without medical complexity, and explore potentially modifiable mechanisms.

METHODS

This study involved a retrospective cohort of 41 905 children ages 2 to 18 seen in 2019 at a single academic medical center. The primary outcome was overweight or obesity, defined as a body mass index of ≥85% for age and sex. CMC was defined as ≥1 serious chronic condition in ≥1 system. Obesogenic conditions and medications were defined as those typically associated with excess weight gain. Multivariable logistic regression was used to adjust for common confounders.

RESULTS

Of the children in the cohort, 29.5% were CMC. Overweight or obesity prevalence was higher among CMC than non-CMC (31.9% vs 18.4%, P ≤.001, adjusted odds ratio [aOR] 1.27, 95% confidence interval [CI] 1.20-1.35). Among CMC, the risk for overweight or obesity was higher among children with metabolic conditions (aOR 2.09, 95% CI 1.88-2.32), gastrointestinal conditions (aOR 1.23 95% CI 1.06-1.41), malignancies (aOR 1.21 95% CI 1.07-1.38), and Spanish-speaking parents (aOR 1.47 95% CI 1.30-1.67). Among overweight or obese CMC, 91.6% had no obesogenic conditions, and only 8.5% had been seen by a registered dietitian in the previous year.

CONCLUSIONS

CMC are significantly more likely to be overweight or obese when compared with children without medical complexity. Although many CMC cases of overweight appear to be preventable, further research is necessary to determine if and how to prevent comorbid obesity among CMC.

The landscape of the long non-coding RNAs and circular RNAs of the abdominal fat tissues in the chicken lines divergently selected for fatness

BACKGROUND

Excessive deposition of abdominal fat poses serious problems in broilers owing to rapid growth. Recently, the evolution of the existing knowledge on long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) have established their indispensable roles in multiple physiological metabolic processes, including adipogenesis and fat deposition. However, not much has been explored on their profiles in the abdominal fat tissues of broilers to date. In the study, we aimed to characterize the vital candidates of lncRNAs and circRNAs and their underlying regulations for abdominal fat deposition in broilers.

RESULTS

The present study sequenced the lncRNAs and circRNAs expression profiles in the abdominal fat tissues isolated from 7-week-old broilers, who were divergently selected for their fatness. It identified a total of 3359 lncRNAs and 176 circRNAs, demonstrating differential expressed (DE) 30 lncRNAs and 17 circRNAs between the fat- and lean-line broilers (|log2FC| ≥ 1, P < 0.05). Subsequently, the 20 cis-targets and 48 trans-targets of the candidate DE lncRNAs were identified for depositing abdominal fat by adjacent gene analysis and co-expression analysis, respectively. In addition, the functional enrichment analysis showed the DE lncRNAs targets and DE circRNAs host genes to be mainly involved in the cellular processes, amino/fatty acid metabolism, and immune inflammation-related pathways and GO terms. Finally, the vital 16 DE lncRNAs located in cytoplasm and specifically expressed in fat/lean line and their targets were used to construct the lncRNA-miRNA-mRNA competing endogenous RNA (ceRNA) regulatory network, comprising 7 DE lncRNAs, 28 miRNAs, 11 DE mRNAs. Notably, three lncRNAs including XR_001468036.2, XR_003077610.1 and XR_001466431.2 with the most connected degrees might play hub regulatory roles in abdominal fat deposition of broilers.

CONCLUSIONS

This study characterized the whole expression difference of lncRNAs and circRNAs between the two lines broilers with divergently ability of abdominal fat. The vital candidate DE lncRNAs/circRNAs and ceRNA regulations were identified related to the deposition of abdominal fat in chicken. These results might further improve our understanding of regulating the non-coding RNAs in obesity.

Bidirectional prediction between weight status and executive function in children and adolescents: A systematic review and meta-analysis of longitudinal studies

This study examined the predictability of child weight status on executive function (EF) and vice versa. We searched PubMed, CINAHL, Web of Science, and EMBASE for longitudinal studies conducted in children and adolescents on October 31, 2021. A pairwise meta-analysis was performed using a frequentist random-effects approach. The quality of all included studies was evaluated using Newcastle-Ottawa Scale and GRADE assessments. This study included 18 longitudinal studies (N = 30,101). Overall executive functioning was a significant negative predictor of child weight status (pooled beta coefficient = -0.14; 95% confidence interval [CI] [-0.22 to -0.07]; I²  = 97%). The pooled odds ratio also revealed that high EF children had a significant lower risk for developing overweight/obesity (odds ratio [OR] = 0.72; 95% CI [0.59 to 0.87]; I²  = 72%). Conversely, child weight status was a significant negative predictor of overall executive functioning (pooled beta coefficient = -0.06; 95% CI [-0.12 to -0.01]; I²  = 81%). These results suggest a bidirectional prediction between child weight status and EF. These predictabilities are low but potentially beneficial for implementation in childcare systems.

Environmental induced transgenerational inheritance impacts systems epigenetics in disease etiology

Environmental toxicants have been shown to promote the epigenetic transgenerational inheritance of disease through exposure specific epigenetic alterations in the germline. The current study examines the actions of hydrocarbon jet fuel, dioxin, pesticides (permethrin and methoxychlor), plastics, and herbicides (glyphosate and atrazine) in the promotion of transgenerational disease in the great grand-offspring rats that correlates with specific disease associated differential DNA methylation regions (DMRs). The transgenerational disease observed was similar for all exposures and includes pathologies of the kidney, prostate, and testis, pubertal abnormalities, and obesity. The disease specific DMRs in sperm were exposure specific for each pathology with negligible overlap. Therefore, for each disease the DMRs and associated genes were distinct for each exposure generational lineage. Observations suggest a large number of DMRs and associated genes are involved in a specific pathology, and various environmental exposures influence unique subsets of DMRs and genes to promote the transgenerational developmental origins of disease susceptibility later in life. A novel multiscale systems biology basis of disease etiology is proposed involving an integration of environmental epigenetics, genetics and generational toxicology.

Novel Zinc-Related Differentially Methylated Regions in Leukocytes of Women With and Without Obesity

Introduction

Nutriepigenetic markers are predictive responses associated with changes in “surrounding” environmental conditions of humans, which may influence metabolic diseases. Although rich in calories, Western diets could be linked with the deficiency of micronutrients, resulting in the downstream of epigenetic and metabolic effects and consequently in obesity. Zinc (Zn) is an essential nutrient associated with distinct biological roles in human health. Despite the importance of Zn in metabolic processes, little is known about the relationship between Zn and epigenetic. Thus, the present study aimed to identify the epigenetic variables associated with Zn daily ingestion (ZnDI) and serum Zinc (ZnS) levels in women with and without obesity.

Materials and Methods

This is a case-control, non-randomized, single-center study conducted with 21 women allocated into two groups: control group (CG), composed of 11 women without obesity, and study group (SG), composed of 10 women with obesity. Anthropometric measurements, ZnDI, and ZnS levels were evaluated. Also, leukocyte DNA was extracted for DNA methylation analysis using 450 k Illumina BeadChips. The epigenetic clock was calculated by Horvath method. The chip analysis methylation pipeline (ChAMP) package selected the differentially methylated regions (DMRs).

Results

The SG had lower ZnS levels than the CG. Moreover, in SG, the ZnS levels were negatively associated with the epigenetic age acceleration. The DMR analysis revealed 37 DMRs associated with ZnDI and ZnS levels. The DMR of PM20D1 gene was commonly associated with ZnDI and ZnS levels and was hypomethylated in the SG.

Conclusion

Our findings provide new information on Zn's modulation of DNA methylation patterns and bring new perspectives for understanding the nutriepigenetic mechanisms in obesity.

MD, Eckel-Passow J, Acosta A. Precision Medicine for Obesity

Obesity is a multifactorial disease with a variable and underwhelming weight loss response to current treatment approaches. Precision medicine proposes a new paradigm to improve disease classification based on the premise of human heterogeneity, with the ultimate goal of maximizing treatment effectiveness, tolerability, and safety. Recent advances in high-throughput biochemical assays have contributed to the partial characterization of obesity's pathophysiology, as well as to the understanding of the role that intrinsic and environmental factors, and their interaction, play in its development and progression. These data have led to the development of biological markers that either are being or will be incorporated into strategies to develop personalized lines of treatment for obesity. There are currently many ongoing initiatives aimed at this; however, much needs to be resolved before precision obesity medicine becomes common practice. This review aims to provide a perspective on the currently available data of high-throughput technologies to treat obesity.

A targeted multi-omics approach reveals paraoxonase-1 as a determinant of obesity-associated fatty liver disease

Background

The multifactorial nature of non-alcoholic fatty liver disease cannot be explained solely by genetic factors. Recent evidence revealed that DNA methylation changes take place at proximal promoters within susceptibility genes. This emphasizes the need for integrating multiple data types to provide a better understanding of the disease’s pathogenesis. One such candidate gene is paraoxonase-1 (PON1). Substantial interindividual differences in PON1 are apparent and could influence disease risk later in life. The aim of this study was therefore to determine the different regulatory aspects of PON1 variability and to examine them in relation to the predisposition to obesity-associated fatty liver disease.

Results

A targeted multi-omics approach was applied to investigate the interplay between PON1 genetic variants, promoter methylation, expression profile and enzymatic activity in an adult patient cohort with extensive metabolic and hepatic characterisation including liver biopsy. Alterations in PON1 status were shown to correlate with waist-to-hip ratio and relevant features of liver pathology. Particularly, the regulatory polymorphism rs705379:C > T was strongly associated with more severe liver disease. Multivariable data analysis furthermore indicated a significant association of combined genetic and epigenetic PON1 regulation. This identified relationship postulates a role for DNA methylation as a mediator between PON1 genetics and expression, which is believed to further influence liver disease progression via modifications in PON1 catalytic efficiency.

Conclusions

Our findings demonstrate that vertical data-integration of genetic and epigenetic regulatory mechanisms generated a more in-depth understanding of the molecular basis underlying the development of obesity-associated fatty liver disease. We gained novel insights into how NAFLD classification and outcome are orchestrated, which could not have been obtained by exclusively considering genetic variation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01142-1.

Simple Energy Balance or Microbiome for Childhood Obesity Prevention?

Obesity prevention interventions generally have either not worked or had effects inadequate to mitigate the problem. They have been predicated on the simple energy balance model, which has been severely questioned by biological scientists. Numerous other etiological mechanisms have been proposed, including the intestinal microbiome, which has been related to childhood obesity in numerous ways. Public health research is needed in regard to diet and the microbiome, which hopefully will lead to effective child obesity prevention.

Cardiometabolic markers among Argentinean normal weight and overweight children with and without central obesity

BACKGROUND

The association between central obesity and cardiometabolic complications justifies exploring its association in normal-weight and overweight/obese (OW/OB) schoolchildren.

OBJECTIVE

To describe cardiometabolic markers in four groups according to BMI/WC categories: (i) normal weight with central OB; (ii) normal weight without central OB; (iii) OW/OB with central OB and (iv) OW/OB without central OB, in a sample of Argentinean schoolchildren.

METHODS

A cross-sectional study of 1264 Argentinean schoolchildren (624 F), aged 9.5 ± 2.2 years was performed between November 2013 and 2015. Children's anthropometric measures, blood pressure (BP), glucose, lipids, and insulin were measured. Children were divided into four groups: (i) normal weight with central OB; (ii) normal weight without central OB; (iii) OW/OB with central OB and (iv) OW/OB without central OB.

RESULTS

The prevalence of normal-weight children without central OB was 64.3% (796), normal weight with central OB 5% (66), OW/OB without central OB 11% (137), and OW/OB with central OB 21% (265). Normal weight with central OB had significantly higher triglycerides than normal-weight children without central OB (86 vs 70 mg/dL, respectively) and OW/OB children without central OB (81 vs 77 mg/dL). Multiple linear regression analyses showed that age, systolic BP, HDL-C, triglycerides, and maternal WC were significantly associated with children's WC; R2 = 0.50 as well as children's BMI; R2 = 0.37.

CONCLUSION

This study found that children with central OB might be at future higher cardiometabolic risk than those without central OB independently of the presence of OW/OB. However, future longitudinal studies should be performed to confirm these findings.

Genetic polymorphisms associated with obesity in the Arab world: a systematic review

BACKGROUND

Obesity, one of the most common chronic health conditions worldwide, is a multifactorial disease caused by complex genetic and environmental interactions. Several association studies have revealed a considerable number of candidate loci for obesity; however, the genotype-phenotype correlations remain unclear. To date, no comprehensive systematic review has been conducted to investigate the genetic risk factors for obesity among Arabs.

OBJECTIVES

This study aimed to systematically review the genetic polymorphisms that are significantly associated with obesity in Arabs.

METHODS

We searched four literature databases (PubMed, Science Direct, Scopus, and Google Scholar) from inception until May 2020 to obtain all reported genetic data related to obesity in Arab populations. Quality assessment and data extraction were performed individually by three investigators.

RESULTS

In total, 59 studies comprising a total of 15,488 cases and 9,760 controls were included in the systematic review. A total of 76 variants located within or near 49 genes were reported to be significantly associated with obesity. Among the 76 variants, two were described as unique to Arabs, as they have not been previously reported in other populations, and 19 were reported to be distinctively associated with obesity in Arabs but not in non-Arab populations.

CONCLUSIONS

There appears to be a unique genetic and clinical susceptibility profile of obesity in Arab patients.

Association Between High Birth Weight and Later Central Obesity in 9-Year-Old Schoolchildren

Background and Objective: Studies have suggested that birth weight (BW) is associated with body mass index (BMI), but its association with waist circumference (WC) in children should be further explored. To determine the association between central obesity (OB) in 9-year-old Argentinean schoolchildren and high BW. Methods: Schoolchildren (n = 2567, 1157 males) aged 8.7 ± 2.1 years from 10 elementary schools in 5 states in Argentina were examined between April 2017 and September 2019. Mothers submitted children's BW information. Pediatricians assessed anthropometric measures and blood pressure (BP). Central OB was defined for children as WC ≥90th percentile for age and gender. Results: The prevalence of overweight (OW) and OB (OW/OB) was 42.7% (1095) and that of central OB was 34.8% (856) in 9-year-old children. The prevalence of low BW (<2500 grams) and high BW (>4000 grams) was 6.6% (n = 169) and 7.4% (n = 190), respectively. BW (3.25 vs. 3.36 kg), weight (31.38 vs. 42.88 kg), BMI (17.29 vs. 22.25 kg/m²), BMI z-scores (z-BMI; 0.25 vs. 1.63), systolic BP (96 vs. 98 mmHg), and diastolic BP (59 vs. 60 mmHg) were significantly lower in 9-year-old children without central OB than in those with central OB, respectively. Multiple logistic regression analysis using central OB as the dependent variable showed that high BW [odds ratio, 1.98 (95% confidence interval 1.44-2.73)] was associated with central OB, adjusted for age, gender, and systolic and diastolic BP. Conclusion: This study shows that central OB in 9-year-old children was associated with high BW. Future longitudinal studies should be performed to confirm this finding. Clinical Registration number, IATIMET-08102019.

Copy number variant analysis and expression profiling of the olfactory receptor-rich 11q11 region in obesity predisposition

Genome-wide copy number surveys associated chromosome 11q11 with obesity. As this is an olfactory receptor-rich region, we hypothesize that genetic variation in olfactory receptor genes might be implicated in the pathogenesis of obesity. Multiplex Amplicon Quantification analysis was applied to screen for copy number variants at chromosome 11q11 in 627 patients with obesity and 330 healthy-weight individuals. A ± 80 kb deletion with an internally 1.3 kb retained segment was identified, covering the three olfactory receptor genes OR4C11, OR4P4, and OR4S2. A significant increase in copy number loss(es) was perceived in our patient cohort (MAF = 27%; p = 0.02). Gene expression profiling in metabolic relevant tissues was performed to evaluate the functional impact of the obesity susceptible locus. All three 11q11 genes were present in visceral and subcutaneous adipose tissue while no expression was perceived in the liver. These results support the 'metabolic system' hypothesis and imply that gene disruption of OR4C11, OR4P4, and OR4S2 will negatively influence energy metabolism, ultimately leading to fat accumulation and obesity. Our study thus demonstrates a role for structural variation within olfactory receptor-rich regions in complex diseases and defines the 11q11 deletion as a risk factor for obesity.

Antibiotic Therapy as a Risk Factor of Obesity Development in Children

Настоящий обзор научной литературы посвящен вопросам, связанным с механизмами антибактериально-индуцированного адипогенеза. Антибиотиками, наиболее высоко ассоциированными с развитием ожирения у детей, считают: амоксициллин, цефотаксим, макролиды, тетрациклины, ванкомицин. На основании результатов филогенетических, метагеномных исследований эффектов антибиотиков установлено, что их применение в антенатальном, раннем постнатальном периоде приводит к пролонгированным изменениям как состава, так и функционирования микробиома, которые ассоциированы с повышенным риском последующего увеличения массы тела ребенка. Механизмы непосредственного влияния антибиотиков на адипогенез связаны с их способностью повышать аппетит за счет стимуляции высвобождения орексина и меланин-концентрирующего гормона; увеличивать абсорбцию пищевых ингредиентов; активировать липогенез; индуцировать митохондриальную дисфункцию и тем самым способствовать накоплению жирных кислот. Применение антибиотиков существенно изменяет структуру микробиома кишечника, а именно: развитие ожирения связано с высоким уровнем представительства бактерий филюмов Actinobacteria и Firmicutes в сочетании со снижением численности бактерий Bacteroidetes, Verrucomicrobia и Faecalibacterium prausnitzii. Антибиотик-индуцированные изменения микробиома могут существенно влиять на аппетит, так как уровень грелина, вызывающего аппетит, положительно коррелирует с представительством бактерий Bacteroides и Prevotella, и отрицательно – с численностью бактерий Bifidobacterium, Lactobacillus, Blautia coccoides и Eubacterium rectale. Доказано, что применение некоторых антибиотиков сопровождается не только накоплением висцерального жира, но и приводит к развитию как неалкогольной болезни печени, так и инсулинорезистентности. Рецепторы FXR и TGR5 являются сенсорами изменений микробиоты кишечника, которые участвуют в регуляции метаболических процессов макроорганизма. Развитие ожирения характеризуется наличием низкоуровневого системного воспаления. При развитии ожирения по мере увеличения размеров адипоцитов фенотип макрофагов меняется на провоспалительный фенотип М1. Накопление провоспалительных клеток в висцеральной жировой ткани является важной причиной развития инсулинорезистентности. В настоящее время необходимость применения антибиотиков при лечении инфекционных заболеваний, вызванных бактериальными агентами, не вызывает никаких клинических сомнений. Однако появление научных сведений о метаболических эффектах, возникновение которых ассоциировано с антибиотикотерапией, ставит клинические новые задачи, решение которых, вероятно, лежит в оптимизации режимов применения антибиотиков и выборе сопровождающих лекарственных средств.

This review of scientific literature is devoted to issues related to the mechanisms of antibacterial- induced adipogenesis. The antibiotics most highly associated with the development of obesity in children are the following: amoxicillin, cefotaxime, macrolides, tetracyclines, vancomycin. On the base of the results of phylogenetic, metagenomic studies of the effects of antibiotics, it was found that their use in the antenatal, early postnatal period leads to prolonged changes in both the composition and functioning of the microbiome, which is associated with the increased risk of subsequent increase of body weight of the child. The mechanisms of direct effect of antibiotics on adipogenesis are associated with their ability to increase appetite, by stimulating the release of orexin and melanin-concentrating hormone; increase the absorption of food ingredients; activate lipogenesis; induce mitochondrial dysfunction and thereby contribute to accumulation of fatty acids. The use of antibiotics significantly changes the structure of the intestinal microbiome, namely, the development of obesity is associated with a high representation of phylum bacteria Actinobacteria and Firmicutes in combination with the decrease of the number of bacteria Bacteroidetes, Verrucomicrobia and Faecalibacterium prausnitzii. Antibiotic-induced changes in the microbiome can significantly affect appetite, because the level of ghrelin that causes appetite positively correlates with the presence of bacteria Bacteroides and Prevotella, and negatively with the number of bacteria Bifidobacterium, Lactobacillus, Blautia coccoides and Eubacterium rectale. It was proved that the use of certain antibiotics is accompanied not only by the accumulation of visceral fat, but also leads to the development of both non-alcoholic liver disease and insulin resistance. The FXR and TGR5 receptors are the sensors of changes in the intestinal microbiota, which is involved in the regulation of the metabolic processes of the macroorganism. The development of obesity is characterized by the presence of low-level systemic inflammation. With the development of obesity, as the size of adipocytes increases, the macrophage phenotype changes to the pro- inflammatory M1 phenotype. The accumulation of pro-inflammatory cells in visceral adipose tissue is an important reason for development of insulin resistance. Currently, the need for antibiotics in the treatment of infectious diseases caused by bacterial agents does not raise any clinical doubts. However, the emergence of scientific information about metabolic effects, the occurrence of which is associated with antibiotic therapy, presents new clinical challenges, the solution of which probably lies in optimizing antibiotic regimens and choosing the accompanying drugs.

Genetic Pathways in Nonalcoholic Fatty Liver Disease: Insights From Systems Biology

Nonalcoholic fatty liver disease (NAFLD) represents a burgeoning worldwide epidemic whose etiology reflects multiple interactions between environmental and genetic factors. Here, we review the major pathways and dominant genetic modifiers known to be relevant players in human NAFLD and which may determine key components of the heritability of distinctive disease traits including steatosis and fibrosis. In addition, we have employed general assumptions which are based on known genetic factors in NAFLD to build a systems biology prediction model that includes functional enrichment. This prediction model highlights additional complementary pathways that represent plausible intersecting signaling networks that we define here as an NAFLD-Reactome. We review the evidence connecting variants in each of the major known genetic modifiers (variants in patatin-like phospholipase domain containing 3, transmembrane 6 superfamily member 2, membrane-bound O-acyltransferase domain containing 7, glucokinase regulator, and hydroxysteroid 17-beta dehydrogenase 13) to NAFLD and expand the associated underlying mechanisms using functional enrichment predictions, based on both preclinical and cell-based experimental findings. These major candidate gene variants function in distinct pathways, including substrate delivery for de novo lipogenesis; mitochondrial energy use; lipid droplet assembly, lipolytic catabolism, and fatty acid compartmentalization; and very low-density lipoprotein assembly and secretion. The NAFLD-Reactome model expands these pathways and allows for hypothesis testing, as well as serving as a discovery platform for druggable targets across multiple pathways that promote NAFLD development and influence several progressive outcomes. In conclusion, we summarize the strengths and weaknesses of studies implicating selected variants in the pathophysiology of NAFLD and highlight opportunities for future clinical research and pharmacologic intervention, as well as the implications for clinical practice.