Subcutaneous Fat Depots Research Articles

Two Regions with Different Expression of Lipogenic Enzymes in Rats’ Posterior Subcutaneous Fat Depot

Lipid metabolism in various adipose tissue depots can differ vastly. This also applies to lipogenesis, the process of synthesizing fatty acids from acetyl-CoA. This study compared the expression of some lipogenic enzymes: fatty acid synthase (FASN), ATP-citrate lyase (ACLY), and malic enzyme 1 (ME1) in different regions of the posterior subcutaneous adipose tissue in rats. Methods and Results: Posterior subcutaneous adipose tissue collected from twelve-month-old Wistar rats was divided into six parts (A–F). The expression of genes encoding lipogenic enzymes was assessed by measuring their activity and mRNA levels using real-time PCR. In the gluteal region of the fat pad, there were much higher levels of activity and mRNA for these lipogenic enzymes compared to the dorsolumbar region. The mRNA level of FASN increased by more than twentyfold, whereas the level of ME1 and ACLY increased eight- and fivefold respectively. This phenomenon was observed in both old and young animals. Furthermore, the lack of uncoupling protein one (Ucp1) expression suggests that neither the presence of brown adipocytes in the gluteal part nor the transformation of white adipocytes into beige contributed to the observed differences. Conclusion: These results indicate that the gluteal white adipose tissue appears to be a unique and separate subcutaneous fat depot.

White adipocytes in subcutaneous fat depots require KLF15 for maintenance in preclinical models.

Healthy adipose tissue is essential for normal physiology. There are 2 broad types of adipose tissue depots: brown adipose tissue (BAT), which contains adipocytes poised to burn energy through thermogenesis, and white adipose tissue (WAT), which contains adipocytes that store lipids. However, within those types of adipose, adipocytes possess depot and cell-specific properties that have important implications. For example, the subcutaneous and visceral WAT confers divergent risk for metabolic disease. Further, within a depot, different adipocytes can have distinct properties; subcutaneous WAT can contain adipocytes with either white or brown-like (beige) adipocyte properties. However, the pathways that regulate and maintain this cell and depot-specificity are incompletely understood. Here, we found that the transcription factor KLF15 is required for maintaining white adipocyte properties selectively within the subcutaneous WAT. We revealed that deletion of Klf15 is sufficient to induce beige adipocyte properties and that KLF15's direct regulation of Adrb1 is a critical molecular mechanism for this process. We uncovered that this activity is cell autonomous but has systemic implications in mouse models and is conserved in primary human adipose cells. Our results elucidate a pathway for depot-specific maintenance of white adipocyte properties that could enable the development of therapies for obesity and associated diseases.

Body fat and circulating leptin levels in the captive short-beaked echidna (Tachyglossus aculeatus)

It is possible that the reproductive strategy of the short-beaked echidna is related to seasonal changes in fat deposition and energy availability, regulated by seasonal changes in endocrine function. We predicted that circulating leptin levels would be directly proportional to adiposity during most of the year, but that a change in this relationship would occur during the pre-breeding season to allow increased fat deposition. To test this hypothesis, we made use of a captive colony of echidnas to describe and quantify changes in fat distribution and the adipostatic hormone leptin. First we assessed seasonal changes in circulating leptin levels, body mass and adiposity for three male and three female adult echidnas maintained on a standard diet. Second, we explored the relationship between circulating leptin levels and increased caloric intake for an additional five adult female echidnas that were provided with supplemented nutrition. Third we visualised fat distribution in male and female adult echidnas using magnetic resonance imaging (MRI) before and after the breeding season, to determine where fat is deposited in this species. For echidnas maintained on the standard diet, there were no seasonal changes in body mass, body fat or plasma leptin levels. However, female echidnas provided with supplemented nutrition had significantly elevated plasma leptin levels during the breeding season, compared to the pre-and post- breeding periods. MRI showed substantial subcutaneous fat depots extending dorso-laterally from the base of the skull to the base of the tail, in both sexes. Pre-breeding season, both sexes had considerable fat deposition in the pelvic/rump region, whilst the female echidna accumulated most fat in the abdominal region. This study shows that male and female echidnas accumulate body fat in the pelvic/rump and the abdominal regions, respectively and that circulating leptin may promote fattening in female echidnas during the breeding season by means of leptin resistance. However, further research is required to evaluate the precise relationship between seasonal changes in leptin and adiposity.

Mechanisms of body fat distribution and gluteal-femoral fat protection against metabolic disorders.

Obesity is a major health problem that affects millions of individuals, and it is associated with metabolic diseases including insulin resistance (IR), type 2 diabetes (T2D), and cardiovascular diseases (CVDs). However, Body fat distribution (BFD) rather than crude obesity is now considered as a more accurate factor associated with these diseases. The factors affecting BFD vary, from genetic background, epigenetic factors, ethnicity, aging, hormonal changes, to lifestyle and medication consumptions. The main goal of controlling BFD comes from the fact that fat accumulation in different depots has a different effect on the overall health and metabolic health of individuals. It is well established that fat storage in the abdominal visceral depot is associated with metabolic disorder occurrence, while gluteal-femoral subcutaneous fat depot seems to be protective against these diseases. In this paper, we will summarize the factors affecting fat distribution. Then, we will present evidence connecting gluteal-femoral fat depot with protection against metabolic disorders including IR, T2D, and CVDs. Finally, we will list the suggested mechanisms that lead to this protective effect. The abstract is visualized in Graphical Abstract.

Lipodystrophy in methylmalonic acidemia associated with elevated FGF21 and abnormal methylmalonylation.

A distinct adipose tissue distribution pattern was observed in patients with methylmalonyl-CoA mutase deficiency, an inborn error of branched-chain amino acid (BCAA) metabolism, characterized by centripetal obesity with proximal upper and lower extremity fat deposition and paucity of visceral fat, that resembles familial multiple lipomatosis syndrome. To explore brown and white fat physiology in methylmalonic acidemia (MMA), body composition, adipokines, and inflammatory markers were assessed in 46 patients with MMA and 99 matched controls. Fibroblast growth factor 21 levels were associated with acyl-CoA accretion, aberrant methylmalonylation in adipose tissue, and an attenuated inflammatory cytokine profile. In parallel, brown and white fat were examined in a liver-specific transgenic MMA mouse model (Mmut-/- TgINS-Alb-Mmut). The MMA mice exhibited abnormal nonshivering thermogenesis with whitened brown fat and had an ineffective transcriptional response to cold stress. Treatment of the MMA mice with bezafibrates led to clinical improvement with beiging of subcutaneous fat depots, which resembled the distribution seen in the patients. These studies defined what we believe to be a novel lipodystrophy phenotype in patients with defects in the terminal steps of BCAA oxidation and demonstrated that beiging of subcutaneous adipose tissue in MMA could readily be induced with small molecules.

Sex and age affect depot expression of Ca2+ channels in rat white fat adipocytes.

White adipose tissue (WAT) requires extracellular Ca2+ influx for lipolysis, differentiation, and expansion. This partly occurs via plasma membrane Ca2+ voltage-dependent channels (CaVs). However, WFA exists in different depots whose function varies with age, sex, and location. To explore whether their CaV expression profiles also differ we used RNAseq and qPCR on gonadal, mesenteric, retroperitoneal, and inguinal subcutaneous fat depots from rats of different ages and sex. CaV expression was found dependent on age, sex, and WFA location. In the gonadal depots of both sexes a significantly lower expression of CaV1.2 and CaV1.3 was seen for adults compared to pre-pubescent juveniles. A lower level of expression was also seen for CaV3.1 in adult male but not female gonadal WFA, the latter of whose expression remained unchanged with age. Relatively little expression of CaV3.2 and 3.2 was observed. In post-pubescent inguinal subcutaneous fat, where the third and fourth mammary glands are located, CaV3.1 was decreased in males but increased in females - thus suggesting that this channel is associated with mammogenesis; however, no difference in intracellular Ca2+ levels or adipocyte size were noted. For all adult depots, CaV3.1 expression was larger in females than males - a difference not seen in pre-pubescent rats. These observations are consistent with the changes of CaV3.1 expression seen in 3T3-L1 cell differentiation and the ability of selective CaV3.1 antagonists to inhibit adipogensis. Our results show that changes in CaV expression patterns occur in fat depots related to sexual dimorphism: reproductive tracts and mammogenesis.

Chenodeoxycholic Acid-Loaded Nanoparticles Are Sufficient to Decrease Adipocyte Size by Inducing Mitochondrial Function.

Excess fat accumulation is not only associated with metabolic diseases but also negatively impacts physical appearance and emotional well-being. Bile acid, the body's natural emulsifier, is one of the few FDA-approved noninvasive therapeutic options for double chin (submental fat) reduction. Synthetic sodium deoxycholic acid (NaDCA) causes adipose cell lysis; however, its side effects include inflammation, bruising, and necrosis. Therefore, we investigated if an endogenous bile acid, chenodeoxycholic acid (CDCA), a well-known signaling molecule, can be beneficial without many of the untoward effects. We first generated CDCA-loaded nanoparticles to achieve sustained and localized delivery. Then, we injected them into the subcutaneous fat depot and monitored adipocyte size and mitochondrial function. Unlike NaDCA, CDCA did not cause cytolysis. Instead, we demonstrate that a single injection of CDCA-loaded nanoparticles into the subcutaneous fat reduced the adipocyte size by promoting fat burning and mitochondrial respiration, highlighting their potential for submental fat reduction.

Impact of Clove and Tulsi supplementation on the dynamics and cellularity of adipose tissue in the visceral and subcutaneous fat depots in Broiler

The substantial genetic enhancement of broiler chickens, coupled with the use of growth-promoting additives in feed, has led to accelerated growth rates, and elevated fat deposition in broiler. Clove and tulsi, well-known medicinal plants, have been shown to improve both the growth performance and intestinal health of broilers. This study aimed to investigate the impact of clove and tulsi supplementation on the composition and cellular makeup in visceral and subcutaneous fat depots of broiler chickens. Sixty Cobb-500 broiler chicks were randomly divided into four groups to receive different supplemental treatments via drinking water. The groups included: S0 (control), receiving no additional supplements; S1, receiving 0.5% clove and 2% tulsi; S2, receiving 1% clove and 3% tulsi; and S3, receiving 1.5% clove and 4% tulsi from day 8 to 28. On days 14 and 28, five broilers from each group were euthanized, and their visceral and subcutaneous fat depots were collected, weighed, and subjected to histological analysis to assess adipocyte histomorphology and histomorphometry. The S1 and S2 groups exhibited higher relative percentages of visceral fat depot, larger adipocyte size, and a greater percentage of larger adipocytes compared to the control, while adipocyte density was lower. Conversely, the S3 group showed minimal deviation from the control. Notably, no significant histomorphological differences were observed among the experimental groups. These findings suggest that clove and tulsi supplementation may modulate adipose tissue dynamics and cellularity depending on the concentration of supplementation.

Disentangling the impact of gluteofemoral versus visceral fat accumulation on cardiometabolic health using sex-stratified Mendelian randomization

Background and aimsIndividuals with a higher abdominal adipose tissue accumulation are at higher risk of developing cardiometabolic diseases. For a given body mass index (BMI), women typically present lower abdominal adipose tissue accumulation compared to men. Whether abdominal adiposity is a causal driver of cardiometabolic risk, or a mere marker of ectopic fat deposition is debated. MethodsWe investigated the sex-specific and sex-combined impact of height and BMI-adjusted gluteofemoral adipose tissue (GFATadj) adjusted abdominal subcutaneous adipose tissue (ASATadj) and adjusted visceral adipose tissue (VATadj) on cardiometabolic traits and diseases using Mendelian randomization. ResultsLeveraging genome-wide summary statistics on GFATadj, ASATadj and VATadj from 39,076 UK Biobank participants with full-body magnetic resonance imaging available, we found that GFATadj is associated with a more favourable cardiometabolic risk profile including lower low density lipoprotein (LDL) cholesterol, triglycerides, fasting glucose, fasting insulin, liver enzyme levels and blood pressure as well as higher high density lipoprotein (HDL) cholesterol levels. GFATadj also is negatively associated with ischemic stroke, coronary artery disease, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD). ASATadj is not associated with cardiometabolic traits and diseases, whereas VATadj is associated with liver fat accumulation but not with NAFLD or other cardiometabolic traits or diseases. Although the absolute effect sizes of GFATadj on LDL cholesterol were more pronounced in women compared to men, most associations did not differ by sex. ConclusionsThe inability of subcutaneous fat depots to efficiently store energy substrates could be the causal factor underlying the association of visceral lipid deposition with cardiometabolic health.

Central obesity is detrimental to anti-inflammatory, phenotype, and exhaustion markers in mononuclear cells - A cross-sectional study

To investigate the role of central obesity on immunometabolic response in peripheral blood mononuclear cells (PBMCs) from normal weight and overweight/obese young men. Eighteen individuals were classified as normal weight (NW; n=9 - age: 25±5 and BMI: 21.4±1.7) and overweight/obese (OW; n=9 - age: 29±7 and BMI: 29.2±2.7). The body composition was evaluated by dual-energy x-ray absorptiometry (DXA), waist circumference, and visceral and subcutaneous fat depots by ultrasound. Physical activity levels, metabolic parameters, immune phenotypic characterization, cytokine production by lipopolysaccharide (LPS) -stimulated whole blood cells and LPS or phorbol 12-myristate 13-acetate (PMA)-stimulated PBMC, and mitochondrial respiration in PBMCs were evaluated. Expression of AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor gamma (PPAR-γ), nuclear factor-kappa B (NF-κB), toll-like receptor 4 (TLR-4), hypoxia-inducible factor-1 alpha (HIF-1α), and adrenergic receptor beta 1 and 2 (AR-β1 and β2) genes were evaluated in cultured PBMC using quantitative real-time polymerase chain reaction (qRT-PCR). Individuals with overweight/obese (OW) presented higher glucose (P=0.009) and leptin (P=0.010) than individuals with normal weight (NW). PBMCs of OW under stimulation with LPS presented a lower production of interleukin-10 (IL-10) (P=0.011) and macrophage inflammatory protein-1alpha (MIP-1α) (P=0.048) than NW. Mitochondrial respiration rates were not different between NW and OW subjects. Cultured PBMCs in LPS-stimulated condition indicated higher gene expression of AR-β2 in OW, while PMA-stimulated PBMCs presented lower expression of AMPK (P=0.002) and higher expression of NF-κB (P=<0.0001) than NW. OW presented higher numbers of CD3+CD4+ T cells (P=0.009) and higher expression of programmed cell death protein 1 (PD-1) in CD8+ T cells (P=0.001) than NW. Central obesity promoted reductions in interleukin 10 production response and increase in AR-β2 expressions in mitogen-stimulated PBMCs. Furthermore, central obesity altered the phenotype of PBMCs, also increasing the expression of PD-1 exhaustion markers in young adults.

Generation of Connective Tissue-Free Microvascular Fragment Isolates from Subcutaneous Fat Tissue of Obese Mice

BACKGROUND:Microvascular fragment (MVF) isolates are generated by short-term enzymatic digestion of adipose tissue and contain numerous vessel segments for the vascularization of tissue defects. Recent findings indicate that the functionality of these isolates is determined by the quality of the fat source. Therefore, we compared MVF isolates from subcutaneous adipose tissue of obese and lean mice.METHODS:MVF isolates were generated from subcutaneous adipose tissue of donor mice, which received a high fat or control diet for 12 weeks. The isolates were analyzed in vitro and in vivo.RESULTS:Feeding of mice with a high fat diet induced obesity with adipocyte hypertrophy, resulting in a significantly lower collagen fraction and microvessel density within the subcutaneous fat depots when compared to lean controls. Accordingly, MVF isolates from obese mice also contained a reduced number of MVF per mL adipose tissue. However, these MVF tended to be longer and, in contrast to MVF from lean mice, were not contaminated with collagen fibers. Hence, they could be freely seeded onto collagen-glycosaminoglycan scaffolds, whereas MVF from lean controls were trapped in between large amounts of collagen fibers that clogged the pores of the scaffolds. In line with these results, scaffolds seeded with MVF isolates from obese mice exhibited a significantly improved in vivo vascularization after implantation into full-thickness skin defects.CONCLUSION:Subcutaneous adipose tissue from obese mice facilitates the generation of connective tissue-free MVF isolates. Translated to clinical conditions, these findings suggest that particularly obese patients may benefit from MVF-based vascularization strategies.

Abstract 037: Neuromodulation Of Adipocyte Activity In Perivascular Adipose Tissue In Healthy Mice

Perivascular adipose tissue (PVAT) has emerged as a regulator of blood pressure by releasing anticontractile factors, which may be disrupted in disease. The production of adipocyte anticontractile factors is driven by norepinephrine (NE), a sympathetic neurotransmitter; however, the source of NE remains unknown. Here, we tested the hypothesis that neuronal innervation of PVAT stimulates adipocytes via NE. Mesenteric (mPVAT), aortic (aPVAT), and subcutaneous fat (sc) depots were studied in healthy male and female mice aged 8-12 weeks. Immunostaining with neuronal and vasculature markers was performed to assess anatomical evidence of neural innervation (n=3 region/sex). Adipocyte activity was studied in Adiponectin Cre;GCaMP 5g-tdT mice, which express the calcium indicator GCaMP5g in adipocytes (125-350 cells/group). Adipocytes were challenged with NE, a parasympathomimetic (bethanechol, 10uM, bath application), and nerve fibers were activated by electrical field stimulation (EFS; +100V, 0.1ms, 10 Hz). Immunolabeling data show that nerve fibers run adjacent to the larger blood vessels within adipose tissue, rather than radiating throughout. Stimulation with NE induced large responses (female: 0.91±0.73, 1.15±0.73, 1.45±0.9 dF/F 0 ; male: 0.75±0.57, 1.01±0.78, 0.73±0.53 dF/F 0 in aPVAT, mPVAT, sc, respectively). Both the parasympathomimetic and EFS induced minimal adipocyte responses compared to NE (% NE = [dF/F 0 bethanechol or EFS / dF/F 0 NE]*100%; bethanechol - female: 39.5%, 13.9%, 9.7%, male: 24.0%, 14.6%, 15.1% in aPVAT, mPVAT, sc, respectively; EFS - female: 31%, 12.2%, 9.7%, male: 28%, 13.9%, 13.7% in aPVAT, mPVAT, sc, respectively). These findings suggest that neural innervation within the PVAT, and functional regulation of adipocytes, is limited. Nerve fibers present within the PVAT are not the primary source of NE driving adipocyte production of anticontractile factors in the PVAT. Rather, this NE originates from other mechanisms including local production by non-neuronal cells or circulation of neurotransmitters.

Visceral adipose microbial and inflammatory signatures in metabolically healthy and unhealthy nonhuman primates.

Obesity is a key risk factor for metabolic syndrome (MetS); however, >10% of lean individuals meet MetS criteria. Visceral adipose tissue (VAT) disproportionately contributes to inflammation and insulin resistance compared with subcutaneous fat depots. The primary aim of this study was to profile tissue microbiome components in VAT over a wide range of metabolic statuses in a highly clinically relevant model. VAT was profiled from nonhuman primates that naturally demonstrate four distinct health phenotypes despite consuming a healthy diet, namely metabolically healthy lean and obese and metabolically unhealthy lean and obese. VAT biopsied from unhealthy lean and obese nonhuman primates demonstrated upregulation of immune signaling pathways, a tissue microbiome enriched in gram-negative bacteria including Pseudomonas, and deficiencies in anti-inflammatory adipose tissue M2 macrophages. VAT microbiomes were distinct from fecal microbiomes, and fecal microbiomes did not differ by metabolic health group, which was in contrast to the VAT bacterial communities. Immune activation with gram-negative VAT microbial communities is a consistent feature in elevated MetS risk in both lean and obesity states.

MicroRNAs-mediated regulation of insulin signaling in white adipose tissue during aging: Role of caloric restriction.

Caloric restriction is a non-pharmacological intervention known to ameliorate the metabolic defects associated with aging, including insulin resistance. The levels of miRNA expression may represent a predictive tool for aging-related alterations. In order to investigate the role of miRNAs underlying insulin resistance in adipose tissue during the early stages of aging, 3- and 12-month-old male animals fed ad libitum, and 12-month-old male animals fed with a 20% caloric restricted diet were used. In this work we demonstrate that specific miRNAs may contribute to the impaired insulin-stimulated glucose metabolism specifically in the subcutaneous white adipose tissue, through the regulation of target genes implicated in the insulin signaling cascade. Moreover, the expression of these miRNAs is modified by caloric restriction in middle-aged animals, in accordance with the improvement of the metabolic state. Overall, our work demonstrates that alterations in posttranscriptional gene expression because of miRNAs dysregulation might represent an endogenous mechanism by which insulin response in the subcutaneous fat depot is already affected at middle age. Importantly, caloric restriction could prevent this modulation, demonstrating that certain miRNAs could constitute potential biomarkers of age-related metabolic alterations.

Isolation methods, proliferation, and adipogenic differentiation of adipose-derived stem cells from different fat depots in bovines.

The adipose-derived stem cells (ASCs) are a valuable resource for regenerative medicine and essential materials for research in fat deposition. However, the isolation procedure of ASCs has not been standardized and needs to be harmonized; differences in proliferation and adipogenic differentiation of ASCs obtained from different fat depots have not been well characterized. In the present study, we compared the efficiency of ASCs isolation by enzymatic treatment and explant culture methods and the proliferation ability and adipogenic differentiation potential of ASCs isolated from subcutaneous and visceral fat depots. The explant culture method was simple and with no need for expensive enzymes while the enzymatic treatment method was complex, time consuming and costly. By the explant culture method, a larger number of ASCs were isolated from subcutaneous and visceral fat depots. By contrast, fewer ASCs were obtained by the enzymatic treatment method, especially from visceral adipose. ASCs isolated by the explant culture method performed well in cell proliferation and adipogenic differentiation, though they were slightly lower than those by the enzymatic treatment method. ASCs isolated from visceral depot demonstrated higher proliferation ability and adipogenic differentiation potential. In total, the explant culture method is simpler, more efficient, and lower cost than the enzymatic treatment method for ASCs isolation; compared with visceral adipose, subcutaneous adipose is easier to isolate ASCs; however, the visceral ASCs are superior to subcutaneous ASCs in proliferation and adipogenic differentiation.

Visceral mesenchymal stem cells from type 2 diabetes donors activate triglycerides synthesis in healthy adipocytes via metabolites exchange and cytokines secretion.

In recent years, there has been an increase in the prevalence of obesity and type 2 diabetes mellitus (T2DM). Development of visceral instead of subcutaneous adipose tissue is pathogenic and increases the risk of metabolic abnormalities. We hypothesize that visceral adipocytes and stromal cells are able to deteriorate other fat depots metabolism via secretory mechanisms. We study the regulatory role of visceral adipose-derived stem cells (vADSC) from donors with obesity and T2DM or normal glucose tolerance (NGT) on healthy subcutaneous ADSC (sADSC) in the Transwell system. Lipid droplets formation during adipogenesis was assessed by confocal microscopy. Cell metabolism was evaluated by 14C-glucose incorporation analysis and western blotting. vADSC secretome was assessed by Milliplex assay. We showed that both NGT and T2DM vADSC had mesenchymal phenotype, but expression of CD29 was enhanced, whereas expressions of CD90, CD140b and IGF1R were suppressed in both NGT and T2DM vADSC. Co-differentiation with T2DM vADSC increased lipid droplet size and stimulated accumulation of fatty acids in adipocytes from healthy sADSC. In mature adipocytes T2DM vADSC stimulated triglyceride formation, whereas NGT vADSC activated oxidative metabolism. Secretome of NGT vADSC was pro-inflammatory and pro-angiogenic in comparison with T2DM vADSC. The present study has demonstrated the critical role of secretory interactions between visceral and subcutaneous fat depots both in the level of progenitor and mature cells. Mechanisms of these interactions are related to direct exchange of metabolites and cytokines secretion.

Oral ω-3 PUFA supplementation modulates inflammation in adipose tissue depots in morbidly obese women: A randomized trial

ObjectivesObesity is characterized by local and systemic low-grade inflammatory responses. Adipose tissue macrophages (ATM) play decisive roles in inflammation, insulin signaling, and various metabolic dysfunctions. Diets enriched with ω-3 polyunsaturated fatty acids (PUFAs) have been shown to improve health and mitigate pathologic conditions. However, the effects of ω-3 PUFA on adipose tissue inflammation, ATM number, and phenotype are poorly defined in human obesity. The aim of this study was to examine differences in expression of metabolic-inflammatory markers in omental, mesenteric, and subcutaneous fat depots of obese women supplemented with ω-3 PUFAs for 4 wk compared with a low-calorie diet before bariatric surgery. MethodsIn a randomized controlled trial, inflammatory markers in the abdominal adipose tissue and the systemic response in obese women were studied. Patients were treated with a 2-wk low-calorie diet (LCD) or a 4-wk ω-3 PUFA-enriched diet (920 mg eicosapentaenoic acid, 760 mg docosahexaenoic acid daily) before laparoscopic bypass surgery. Omental, mesenteric, and subcutaneous adipose tissue biopsies were collected during surgery and analyzed for quantity and phenotype of ATMs, and profiled for adipokines, cytokines, and signal transduction molecules. ResultsThe chronic inflammatory state characterized by ATM markers was mostly improved by ω-3 PUFAs in visceral adipose tissue. We observed a decreased expression of CD45, CCL2, and CD68, indicating a lower inflammatory state. In patients with type 2 diabetes, ω-3 PUFAs lowered the expression of Netrin-1. ConclusionsCompared with an LCD, a diet enriched with ω-3 PUFAs influences the inflammatory state in different adipose tissue depots, by affecting markers of adipose tissue inflammation, macrophage phenotype, and retention. However, this was not reflected in clinical parameters such as insulin resistance and inflammatory cytokines. Subcutaneous adipose tissue and visceral adipose tissue have different responses to an LCD or a ω-3 PUFA-enriched diet. The presence of diabetes modifies the expression of inflammatory markers.

Integrative Analysis of Blood Transcriptomics and Metabolomics Reveals Molecular Regulation of Backfat Thickness in Qinchuan Cattle

A crucial goal of reducing backfat thickness (BFT) is to indirectly improve feed conversion efficiency. This phenotype has been reported in certain papers; however, the molecular mechanism has yet to be fully revealed. Two extreme BFT groups, consisting of four Qinchuan cattle, were chosen for this study. We performed metabolite and transcriptome analyses of blood from cattle with a high BFT (H-BFT with average = 1.19) and from those with a low BFT (L-BFT with average = 0.39). In total, 1106 differentially expressed genes (DEGs) and 86 differentially expressed metabolites (DEMs) were identified in the extreme trait. In addition, serum ceramide was strongly correlated with BFT and could be used as a potential biomarker. Moreover, the most notable finding was that the functional genes (SMPD3 and CERS1) and metabolite (sphingosine 1-phosphate (S1P)) were filtered out and significantly enriched in the processes related to the sphingolipid metabolism. This investigation contributed to a better understanding of the subcutaneous fat depots in cattle. In general, our results indicated that the sphingolipid metabolism, involving major metabolites (serum ceramide and S1P) and key genes (SMPD3 and CERS1), could regulate BFT through blood circulation.

BMI-adjusted adipose tissue volumes exhibit depot-specific and divergent associations with cardiometabolic diseases

For any given body mass index (BMI), individuals vary substantially in fat distribution, and this variation may have important implications for cardiometabolic risk. Here, we study disease associations with BMI-independent variation in visceral (VAT), abdominal subcutaneous (ASAT), and gluteofemoral (GFAT) fat depots in 40,032 individuals of the UK Biobank with body MRI. We apply deep learning models based on two-dimensional body MRI projections to enable near-perfect estimation of fat depot volumes (R2 in heldout dataset = 0.978-0.991 for VAT, ASAT, and GFAT). Next, we derive BMI-adjusted metrics for each fat depot (e.g. VAT adjusted for BMI, VATadjBMI) to quantify local adiposity burden. VATadjBMI is associated with increased risk of type 2 diabetes and coronary artery disease, ASATadjBMI is largely neutral, and GFATadjBMI is associated with reduced risk. These results – describing three metabolically distinct fat depots at scale – clarify the cardiometabolic impact of BMI-independent differences in body fat distribution.

RF10 | PMON205 LH/CG Receptor Activation Protects Mice from Diet-Induced Obesity and Modifies Adipose Tissue Immune Response

Abstract Menopause is associated with the loss of LH ovulatory surges and enhanced visceral adiposity. Visceral fat depots increase from 5-8% at premenopause to 15-20% of total body fat at postmenopause. Here, we report that high-dose LH, hCG, or small molecule LH/CGR agonist ORG43553 injected twice-a-week into 14-weeks-old C57BL/6 male mice protects them from diet-induced obesity. Testosterone levels were elevated in mice treated with LH or hCG, but not with ORG43553. Notably, the anti-obesity action of LH/hCG is independent of testosterone, as blocking the androgen receptor using flutamide yielded similar results. Importantly, male Lhcgr knockout mice on a high-fat diet treated with LH failed to display a reduction in adiposity, confirming the in vivo specificity of action. Furthermore, our data phenocopied Lhcgr haploinsufficiency in mice. We confirmed the presence of Lhcgr in mouse genital and inguinal fat pads, adipose-derived stromal vascular cells, as well as in differentiated and undifferentiated 3T3-L1 murine adipocytes by qPCR, RNAscope in situ hybridization, and immunohistochemistry. Sanger sequencing showed that the extracellular domain of Lhcgr in genital fat depot was identical to the ovarian receptor. Similarly, we identified LHCGR in human subcutaneous and visceral fat depots. Binding of intraperitoneally injected AlexaFluor-488-labeled hCG was found not only in mouse ovary, but also in genital and subcutaneous fat pad, further confirming the presence of LHCGR in adipose tissue. This binding could be competitively displaced in 3T3-L1 cells using unlabeled hCG. LH, hCG and ORG43553 activated ERK1/2 in a dose-dependent manner in undifferentiated and differentiated 3T3-L1 cells, suggesting that the adipose LHCGR is fully functional. LH, hCG, and ORG43553 reduced adipogenic differentiation in 3T3-L1 cells, which is further confirmed by RNA sequencing. Moreover, we observed, that LH and hCG also alters several aspects of immune response in adipose tissue, including inflammatory response and adaptive immunity. In conclusion, we demonstrated that LH/CG receptors are present and fully functional in adipose tissue, and that high-dose intermittent activation of LHCGR in mouse fat depots protects mice from diet-induced obesity and modifies adipose tissue immune response. Presentation: Saturday, June 11, 2022 1:42 p.m. - 1:47 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.