Weight loss after Roux-En-Y gastric bypass surgery reveals skeletal muscle DNA methylation changes

Lower levels of plasma syndecan-4 are associated with loss of body weight and fat-free mass after bariatric surgery

OBJECTIVE

Bariatric surgery induces a significant loss of both fat mass (FM) and fat-free mass (FFM). The proteoglycan receptor syndecan-4 (SDC4) plays a crucial role in adipose tissue and skeletal muscle functions. Thus, this study was performed (i) to assess plasma SDC4 levels after both Sleeve Gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB) surgeries, and (ii) to explore potential associations with changes in body composition variables.

RESULTS

Twenty-six patients (17 females) with severe obesity underwent SG (n = 13) or RYGB (n = 13) and were followed up to 1 year (1Y). Body weight, FM, FFM, and SCD4 were measured at baseline (BL), and at week 11 (W11) and 1Y after surgery. Independently of procedure, there was a significant body weight loss at W11, with an average FM and FFM reduction of 13.7 ± 0.6 kg and 5.3 ± 0.5 kg, respectively. Participants continued to lose weight afterwards, with a total weigth loss of 38.2 ± 1.5 kg at 1Y. No associations were found at BL between SDC4 levels and any anthropometric variable; however, SDC4 levels were lower than BL at both W11 and 1Y, independently of type of surgery. Additionally, changes in SDC4 between BL and 1Y were positively correlated with weight and FFM loss during the same period.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04051190 on 09/08/2019.

Novel markers and networks related to restored skeletal muscle transcriptome after bariatric surgery

OBJECTIVE

The aim of this study was to discover novel markers underlying the improvement of skeletal muscle metabolism after bariatric surgery.

METHODS

Skeletal muscle transcriptome data of lean people and people with obesity, before and 1 year after bariatric surgery, were subjected to weighted gene co-expression network analysis (WGCNA) and least absolute shrinkage and selection operator (LASSO) regression. Results of LASSO were confirmed in a replication cohort.

RESULTS

The expression levels of 440 genes differing between individuals with and without obesity were no longer different 1 year after surgery, indicating restoration. WGCNA clustered 116 genes with normalized expression in one major module, particularly correlating to weight loss and decreased plasma free fatty acids (FFA), 44 of which showed an obesity-related phenotype upon deletion in mice. Among the genes of the major module, 105 represented prominent markers for reduced FFA concentration, including 55 marker genes for decreased BMI in both the discovery and replication cohorts.

CONCLUSIONS

Previously unknown gene networks and marker genes underlined the important role of FFA in restoring muscle gene expression after bariatric surgery and further suggest novel therapeutic targets for obesity.

The impact of maternal bariatric surgery on long-term health of offspring: a scoping review

While pregnancy post-bariatric surgery has become increasingly common, little is known about whether and how maternal bariatric surgery affects the next generation. This scoping review aimed to collate available evidence about the long-term health of offspring following maternal bariatric surgery. A literature search was conducted using three databases (PubMed, PsycINFO, EMBASE) to obtain relevant human and animal studies. A total of 26 studies were included: 17 were ancillary reports from five "primary" studies (three human, two animal studies) and the remaining nine were "independent" studies (eight human, one animal studies). The human studies adopted sibling-comparison, case-control, and single-group descriptive designs. Despite limited data and inconsistent results across studies, findings suggested that maternal bariatric surgery appeared to (1) modify epigenetics (especially genes involved in immune, glucose, and obesity regulation); (2) alter weight status (unclear direction of alteration); (3) impair cardiometabolic, immune, inflammatory, and appetite regulation markers (primarily based on animal studies); and (4) not affect the neurodevelopment in offspring. In conclusion, this review supports that maternal bariatric surgery has an effect on the health of offspring. However, the scarcity of studies and heterogenous findings highlight that more research is required to determine the scope and degree of such effects. IMPACT: There is evidence that bariatric surgery modifies epigenetics in offspring, especially genes involved in immune, glucose, and obesity regulation. Bariatric surgery appears to alter weight status in offspring, although the direction of alteration is unclear. There is preliminary evidence that bariatric surgery impairs offspring's cardiometabolic, immune, inflammatory, and appetite regulation markers. Therefore, extra care may be needed to ensure optimal growth in children born to mothers with previous bariatric surgery.

DNA Methylation Remodeling after Bariatric Surgery Correlates with Clinical Parameters

The altered functions of adipose tissue are one of the main issues in obesity. Bariatric surgery is associated with improvement of obesity associated comorbidities. Here DNA methylation remodeling in adipose tissue after bariatric surgery is examined. After six months postoperative, DNA methylation shows changes in 1155 CpG sites, 66 of these sites correlate with body mass index. Some sites also show correlation with LDL-C, HDL-C, total cholesterol, and triglycerides. CpG sites are located in genes that have not previously been linked to obesity or metabolic diseases. GNAS complex locus is one of those that presented CpG site with the greatest changes after surgery, and the most significant correlation with BMI and lipid profiles. These results show that epigenetic regulation may be involved in the alteration of adipose tissue functions in obesity.

Identification of a novel immune-related transcriptional regulatory network in sarcopenia

BACKGROUND

Sarcopenia is highly prevalent in elderly individuals and has a significant adverse effect on their physical health and quality of life, but the mechanisms remain unclear. Studies have indicated that transcription factors (TFs) and the immune microenvironment play a vital role in skeletal muscle atrophy.

METHODS

RNA-seq data of 40 muscle samples were downloaded from the GEO database. Then, differentially expressed genes (DEGs), TFs(DETFs), pathways(DEPs), and the expression of immune gene sets were identified with limma, edgeR, GO, KEGG, ORA, GSVA, and ssGSEA. Furthermore, the results above were integrated into coexpression analysis by Pearson correlation analysis (PCA). Significant coexpression patterns were used to construct the immune-related transcriptional regulatory network by Cytoscape and potential medicine targeting the network was screened by Connectivity Map. Finally, the regulatory mechanisms and RNA expression of DEGs and DETFs were identified by multiple online databases and RT‒qPCR.

RESULTS

We screened 808 DEGs (log2 fold change (FC) > 1 or <  - 1, p < 0.05), 4 DETFs (log2FC > 0.7 or <  - 0.7, p < 0.05), 304 DEPs (enrichment scores (ES) > 1 or <  - 1, p < 0.05), and 1208 differentially expressed immune genes sets (DEIGSs) (p < 0.01). Based on the results of PCA (correlation coefficient (CC) > 0.4 or <  - 0.4, p < 0.01), we then structured an immune-related network with 4 DETFs, 9 final DEGs, 11 final DEPs, and 6 final DEIGSs. Combining the results of online databases and in vitro experiments, we found that PAX5-SERPINA5-PI3K/Akt (CC ≤ 0.444, p ≤ 0.004) was a potential transcriptional regulation axis, and B cells (R = 0.437, p = 0.005) may play a vital role in this signal transduction. Finally, the compound of trichostatin A (enrichment = -0.365, specificity = 0.4257, p < 0.0001) might be a potential medicine for sarcopenia based on the PubChem database and the result of the literature review.

CONCLUSIONS

We first identified immune-related transcriptional regulatory network with high-throughput RNA-seq data in sarcopenia. We hypothesized that PAX5-SERPIAN5-PI3K/Akt axis is a potential mechanism in sarcopenia and that B cells may play a vital role in this signal transduction. In addition, trichostatin A might be a potential medicine for sarcopenia.

Molecular remodeling of adipose tissue is associated with metabolic recovery after weight loss surgery

BACKGROUND

Bariatric surgery is an effective therapy for individuals with severe obesity to achieve sustainable weight loss and to reduce comorbidities. Examining the molecular signature of subcutaneous adipose tissue (SAT) following different types of bariatric surgery may help in gaining further insight into their distinct metabolic impact.

RESULTS

Subjects undergoing biliopancreatic diversion with duodenal switch (BPD-DS) showed a significantly higher percentage of total weight loss than those undergoing gastric bypass or sleeve gastrectomy (RYGB + SG) (41.7 ± 4.6 vs 28.2 ± 6.8%; p = 0.00005). Individuals losing more weight were also significantly more prone to achieve both type 2 diabetes and dyslipidemia remission (OR = 0.75; 95%CI = 0.51-0.91; p = 0.03). Whole transcriptome and methylome profiling showed that bariatric surgery induced a profound molecular remodeling of SAT at 12 months postoperative, mainly through gene down-regulation and hypermethylation. The extent of changes observed was greater following BPD-DS, with 61.1% and 49.8% of up- and down-regulated genes, as well as 85.7% and 70.4% of hyper- and hypomethylated genes being exclusive to this procedure, and mostly associated with a marked decrease of immune and inflammatory responses. Weight loss was strongly associated with genes being simultaneously differentially expressed and methylated in BPD-DS, with the strongest association being observed for GPD1L (r² = 0.83; p = 1.4 × 10^-6).

CONCLUSIONS

Present findings point to the greater SAT molecular remodeling following BPD-DS as potentially linked with higher metabolic remission rates. These results will contribute to a better understanding of the metabolic pathways involved in the response to bariatric surgery and will eventually lead to the development of gene targets for the treatment of obesity. Trial registration ClinicalTrials.gov NCT02390973.

Can Exercise Training Alter Human Skeletal Muscle DNA Methylation?

Skeletal muscle is highly plastic and dynamically regulated by the body’s physical demands. This study aimed to determine the plasticity of skeletal muscle DNA methylation in response to 8 weeks of supervised exercise training in volunteers with a range of insulin sensitivities. We studied 13 sedentary participants and performed euglycemic hyperinsulinemic clamps with basal vastus lateralis muscle biopsies and peak aerobic activity (VO2 peak) tests before and after training. We extracted DNA from the muscle biopsies and performed global methylation using Illumina’s Methylation EPIC 850K BeadChip. Training significantly increased peak aerobic capacity and insulin-stimulated glucose disposal. Fasting serum insulin and insulin levels during the steady state of the clamp were significantly lower post-training. Insulin clearance rates during the clamp increased following the training. We identified 13 increased and 90 decreased differentially methylated cytosines (DMCs) in response to 8 weeks of training. Of the 13 increased DMCs, 2 were within the following genes, FSTL3, and RP11-624M8.1. Of the 90 decreased DMCs, 9 were within the genes CNGA1, FCGR2A, KIF21A, MEIS1, NT5DC1, OR4D1, PRPF4B, SLC26A7, and ZNF280C. Moreover, pathway analysis showed an enrichment in metabolic and actin-cytoskeleton pathways for the decreased DMCs, and for the increased DMCs, an enrichment in signal-dependent regulation of myogenesis, NOTCH2 activation and transmission, and SMAD2/3: SMAD4 transcriptional activity pathways. Our findings showed that 8 weeks of exercise training alters skeletal muscle DNA methylation of specific genes and pathways in people with varying degrees of insulin sensitivity.