Human Adipose Tissue Research Articles

Human peripancreatic adipose tissue paracrine signaling impacts insulin secretion, blood flow, and gene transcription.

Adipose tissue accumulation around non-adipose tissues is associated with obesity and metabolic disease. One relatively unstudied depot is peripancreatic adipose tissue (PAT) that accumulates in obesity and insulin resistance and may impact beta cell function. Pancreatic lipid accumulation and PAT content are negatively related to metabolic outcomes in humans, but these studies are limited by the inability to pursue mechanisms. We obtained PAT from human donors through the Human Pancreas Analysis Program to evaluate differences in paracrine signaling compared to subcutaneous adipose tissue (SAT), as well as effects of the PAT secretome on aortic vasodilation, human islet insulin secretion, and gene transcription using RNAseq. PAT had greater secretion of IFN-γ and most inflammatory eicosanoids compared to SAT. Secretion of adipokines negatively related to metabolic health were also increased in PAT compared to SAT. We found no overall effects of PAT compared to SAT on human islet insulin secretion, however, insulin secretion was suppressed after PAT exposure from men compared to women. Vasodilation was significantly dampened by PAT conditioned media, an effect explained almost completely by PAT from men and not women. Islets treated with PAT showed selective changes in lipid metabolism pathways while SAT altered cellular signaling and growth. RNAseq analysis showed changes in islet gene transcription impacted by PAT compared to SAT, with the biggest changes found between PAT based on sex. The PAT secretome is metabolically negative compared to SAT, and impacts islet insulin secretion, blood flow, and gene transcription in a sex dependent manner.

Collagen Isolated from Human Adipose Tissue and Its Cellular Affinity.

The use of collagen in cell cultures promotes cell proliferation and differentiation, and it has been commercialized. In this study, we separated and purified collagen from adipose tissue discarded during liposuction and prepared collagen-coated dishes. After collagen was identified from human adipose tissue, type identification and quantification were performed using SDS-PAGE and FPLC. Collagen type I was used to coat culture dishes. Human skin fibroblasts and human adipose tissue-derived stem cells were seeded at a density of 2.5×105 cells/mL on prepared dishes at a collagen concentration of 3 mg/mL and cultured for 7 days. Cell viability was then measured and analyzed. The WST-1 assay was used to evaluate the results. The amount of collagen in 300 g of adipose tissue was 25.5 mg for type I, 41.4 mg for type III, 10.6 mg for type IV, 6.5 mg for type V, and 15 mg for type VI. The highest rates were observed for adipose stem cells cultured on human adipose tissue-derived collagen-coated dishes. In cell cultures, cell affinity was higher when cells and the substrate used were of the same origin, and affinity was stronger when the tissue of origin was the same.

Metabolomic reprogramming of subcutaneous adipose tissue aggravates atherosclerosis via impaired adipocyte-macrophage crosstalk

Abstract Object: The bidirectional relationship between cardiometabolic syndrome and dysfunctional adipose tissue has received increasing attention. However, the metabolic alteration of subcutaneous adipose tissue during atherosclerosis has been overlooked. Methods In this study, we aimed to investigate the relationship between subcutaneous adipose tissue and atherosclerosis based on a combination strategy of single-cell sequencing and metabolomics in atherosclerotic mice and humans. Result Through our analysis of the clinical cohort with atherosclerosis, we discovered a correlation between the volume of subcutaneous adipose tissue and the characteristics of coronary plaques. Furthermore, by employing the snRNA-seq approach, we identified the metabolic landscape and cellular crosstalk within the subcutaneous adipose tissue of atherosclerotic mice. Lastly, through our analysis of the metabolic features in human adipose tissue, we successfully validated the Insulin-like Growth Factor 1 pathway as a crucial modulator in the adipocyte-macrophage crosstalk during the development of atherosclerosis. Conclusion The present study has provided further evidence that dysregulated metabolism of subcutaneous adipose tissue is involved in the development and progression of atherosclerosis, not only in humans but also in animal models.

Human epicardial adipose tissue secretome alters metabolomic profile and induces endothelial-to-mesenchymal transition in human lymphatic endothelial cells

Abstract Background Cardiac lymphatic systems play an important role in maintaining myocardial fluid homeostasis during inflammation. We have recently reported the epicardial adipose tissue (EAT)-derived factor induces inflammation and fibrosis in atrial myocardium, which lead to atrial fibrillation (AF). However, the direct effect of EAT on the cardiac lymphatic endothelial cells (LECs) remains unknown. Objective To elucidate the effect of EAT on cardiac LECs, as one of the potential causes of AF. Methods Human EAT samples were collected from 18 consecutive patients with or without AF patients during cardiovascular surgery. They were categorized into the sinus rhythm (SR) group (n=9, 72.7±8.6 years) and the AF group (n=9, 73.3±7.4 years). Preadipocytes were extracted from EAT by homogenization and collagenase treatment, and cultured to confluence. After differentiation to mature adipocytes, cell culture supernatant was collected, and cultured with human LECs. Cell permeability was measured by using FITC-dextran assay. Tube forming ability was analyzed by seeding LECs on the extracellular matrix gels. Metabolomic profiling of LECs was performed by GC-MS system. Results RT-PCR analysis revealed that cell culture supernatant from mature adipocytes of AF patients significantly increased mRNA expression of mesenchymal marker, TAGLN/SM22a (p<0.01) in human LECs, whereas mRNA expression of lymphatic endothelial markers, LYVE1 (p=0.0552) and PROX1 (p=0.0231) were decreased in human LECs, compared to those from mature adipocytes of SR patients. These data suggest cell culture supernatant from mature adipocytes of AF patients highly induce endothelial-to-mesenchymal transition (EndMT) of LECs. When assessing the endothelial barrier function by using FITC-dextran, cell culture supernatant from mature adipocytes of AF patients significantly decreased cell barrier function (p<0.01) compared to those from mature adipocytes of SR patients. Furthermore, cell culture supernatant from mature adipocytes of AF patients significantly decreased the tube forming ability of LECs (p<0.01) compared to those from mature adipocytes of SR patients. To assess the metabolomic changes in human LECs by EAT-secretome, we conducted the GC/MS analysis. Cell culture supernatant from mature adipocytes of AF patients significantly decreased several amino acids including branched-chain amino acid (BCAA; valine, leucine and isoleucine), compared to those from mature adipocytes of SR patients. Conclusion Our study with human EAT and LECs demonstrated that EAT-secretome from AF patients altered metabolomic profile in LECs, and highly caused EndMT in LECs, leading to impaired barrier function and the tube forming ability. Defects of lymphangiogenesis could be a therapeutic target for atrial cardiomyopathy.

Impact of glucose fluctuation on the paracrine secretome profile of human epicardial adipocyte

Abstract Background Glucose fluctuations (GF) is known to be the significant factor related to poor cardiovascular outcome in the diabetic patients. We investigated the potential impact of GF on paracrine effect of human epicardial adipocyte on cardiomyocyte. Methods Human EAT biopsies obtained during surgery and isolated preadipocyte/adipocytes were used to evaluate the direct impact of GF on the adipocytes. Matured adipocytes were exposed to the media containing normal glucose (100 mg/dl, NG), high glucose (300 mg/dl, HG), or high-low glucose (75-300 mg/dl, GF) for 1 week. Transcriptomic profiling of the cultured matured adipocyte was performed using microarray analysis. The impact of GF on the paracrine effect of adipocyte was evaluated using a co-culture with human iPS-derived atrial cardiomyocytes and the adipocytes. Clinical association study verified the validity of the findings. Results GF for 1 week altered the expression of 595 differentially expressed genes (up-regulated or down-regulated) with an effect size of >50% or `−50% and a significant statistical difference (P < 0.05) in human epicardial adipocytes, while the continuous HG for 1 week altered the expression of only 182 differentially expressed genes. Of the genes affected by GF, top 3 most affected genes included IL1β, IL33, IL8. Regarding the other major pro-inflammatory cytokines, IL1α, CCL2 and IL6 were also significantly increased in the adipocyte treated with GF, however these were not increased in the adipocyte treated with HG. Co-culture of human iPS cell-derived atrial cardiomyocytes and adipocytes treated with NG, HG and GF revealed that GF-treated adipocyte strikingly increased oxidative stress in the cardiomyocyte through the paracrine effect. In the real-world clinical association study, IL1β mRNA expression in human epicardial adipose tissue showed significant positive correlation with the severity of GF during hospitalization and oxidative stress in the left atrial myocardium. Conclusions GF adversely affect the paracrine secretome profile of human epicardial adipocyte. IL1β may be a critical epicardial adipocyte-derived adipokine that is enhanced by GF.

Cellular Characteristics and Protein Signatures of Human Adipose Tissues from Donors With or Without Advanced Coronary Artery Disease

Background/Objectives: Perivascular adipose tissue (PVAT) exerts a paracrine effect on blood vessels and our objective was to understand PVAT molecular signatures related to cardiovascular disease. Methods: We studied two groups: those undergoing mitral valve repair/replacement (VR, n = 16) and coronary artery bypass graft (CABG, n = 38). VR donors did not have coronary artery disease, whereas CABG donors had advanced coronary artery disease. Clinical and tissue pathologies and proteomics from adipose tissue were assessed. Results: Donors undergoing VR had a lower body mass index (p = 0.01), HbA1C (p = 0.0023), and incidence of diabetes (p = 0.022) compared to CABG. VR donors were overall healthier, with higher cardiac function compared to CABG donors, based on ejection fraction. Although adipose histopathology between groups was not markedly different, PVAT had smaller and more adipocytes compared to subcutaneous adipose tissues. These differences were validated by whole specimen automated morphological analysis, and anisotropy analysis showed small (2.8–7.5 μm) and large (22.8–64.4 μm) scale differences between perivascular and subcutaneous adipose tissue from CABG donors, and small scale changes (2.8–7.5 μm) between perivascular and subcutaneous adipose tissue from VR donors. Distinct protein signatures in PVAT and subcutaneous adipose tissue include those involved in secretion, exosomes and vesicles, insulin resistance, and adipocyte identity. Comparing PVAT and subcutaneous adipose tissue from CABG donors, there were 82 significantly different proteins identified with log fold change ≥ 0.3 or ≤−0.3 (p < 0.05). Using this threshold, there were 36 differences when comparing PVAT and subcutaneous adipose tissue from VR donors, 58 differences when comparing PVAT from CABG or VR donors, and 55 when comparing subcutaneous adipose tissue from CABG vs. VR donors. Conclusions: Routine histopathology cannot differentiate between PVAT from donors with or without coronary artery disease, but multiscale anisotropy analysis discriminated between these populations. Our mass spectrometry analysis identified a cohort of proteins that distinguish between adipose depots, and are also associated with the presence or absence of coronary artery disease.

Acquisition of durable insulin-producing cells from human adipose tissue-derived mesenchymal stem cells as a foundation for cell- based therapy of diabetes mellitus

This study aimed to identify the suitable induction protocol to produce highly qualified insulin producing cells (IPCs) from human adipose tissue derived stem cells (ADSCs) and evaluate the efficacy of the most functionally IPCs in management of diabetes mellitus (DM) in rats. The ADSCs were isolated and characterized according to the standard guidelines. ADSCs were further induced to be IPCs in vitro using three different protocols. The success of trans-differentiation was assessed in vitro through analysis of pancreatic endocrine genes expression, and insulin release in response to glucose stimulation. Then, the functionalization of the generated IPCs was evaluated in vivo. The in vitro findings revealed that the laminin-coated plates in combination with insulin-transferrin-selenium, B27, N2, and nicotinamide could efficiently up-regulate the expression of pancreatic endocrine genes. The in vivo study indicated effectual homing of the PKH-26-labelled IPCs in the pancreas of treated animals. Moreover, IPCs infusion in diabetic rats induced significant improvement in the metabolic parameters and prompted considerable up-regulation in the expression of the pancreatic related genes. The regenerative effect of infused IPCs was determined through histological examination of pancreatic tissue. Conclusively, the utilization of laminin–coated plates in concomitant with extrinsic factors promoting proliferation and differentiation of ADSCs could efficiently generate functional IPCs.

8159 Single Nuclei RNA-Sequencing Reveals Novel Cellular Diversity in Human Neck Adipose Tissue

Abstract Disclosure: H. Camara: None. S.D. Kodani: Employee; Self; Hoxton Farm. S. Yang: None. V. Efthymiou: None. K. An: None. A. Gupta: None. F. Shamsi: None. A. Streets: None. M.E. Patti: Advisory Board Member; Self; Fractyl Laboratories. Consulting Fee; Self; AstraZeneca, Hamni, MBX Biosciences. Grant Recipient; Self; Dexcom. Y. Tseng: Consulting Fee; Self; LyGenesis. Other; Self; BioHaven. Adipose tissue plays a crucial role in maintaining metabolic health. It fulfills distinct functions through two types of fat: white adipose tissue (WAT), the primary site of triglyceride storage, and brown adipose tissue (BAT) along with related beige fat, specializing in thermogenic energy expenditure. Despite the scarcity of BAT in humans, these thermogenic adipocytes efficiently utilize glucose and triglycerides and act as an endocrine organ by secreting batokines. Hence, increased BAT activity is associated with improved metabolic health in humans. In adults, thermogenic adipose tissue is localized in deep neck planes, exhibiting a gradient from white to beige/brown from superficial to deep layers. Mounting evidence suggests the diverse cell types within the adipose tissue and their dynamic interactions play an important role in its versatile functions. To understand the cellular compositions of human adipose tissue and directly compare the differences between human BAT vs. WAT, we collected 30 paired samples of superficial, intermediate and deep human neck adipose tissue from 15 participants who underwent anterior cervical discectomy fusion or thyroid surgery and subjected the frozen tissues to single-nucleus RNA sequencing (snRNA-seq). The integration of the samples yielded 41,337 good-quality nuclei. As expected, white adipocytes (WAd) were the dominant cell type, comprising 38% of the total cells captured. Further analysis of the WAd cluster revealed increased expression of brown adipocyte-associated genes, such as EBF2 and COBL, and enrichment of oxidative phosphorylation pathway score in cells from deep neck samples, indicating increased thermogenic potential. Bona fide brown adipocytes (BAds), marked by the expression of PPARGC1A, were predominantly located in the deep neck samples (>80%) but comprised less than 2% of the dataset. Despite their low numbers, cell-cell communication analysis by CellChat predicted that BAds account for most of the communication events within this niche, highlighting their endocrine importance. snRNA-seq also captured non-adipocyte cells, including adipocyte progenitors, smooth muscle, immune, Schwann and neuron-associated cells. Among these, a novel Neuron-Associated Cell-1, marked by the expression of CNTNAP2, emerged as the second most abundant in the dataset (∼10% of total). Another neuron-associated cell population marked by expression of DNAH11, though less abundant (∼1%), was enriched in deep neck samples, potentially regulating the high levels of thermogenic potential in this region. Taken together, the identified subpopulations and their gene expression profiles offer new insights into the tissue's role in metabolic regulation. This knowledge could be pivotal for developing targeted therapies for obesity and related disorders. Presentation: 6/1/2024

6711 Single Nuclei RNA-seq To Map Adipose Cellular Populations And Senescent Cells In Response To A Lifestyle Or Senolytic Intervention In Older Adults With Obesity: A Double-Blind, Placebo-Controlled, Randomized Trial

Abstract Disclosure: A. Aslamy: None. G. Connolly: None. J. Nie: None. S. Espinoza: None. M. Serra: None. N. Musi: None. It is well established that obese and older individuals are at significantly increased risk for diabetes and metabolic syndrome. However, the underlying molecular mechanisms by which increased adiposity and aging predisposes individuals to metabolic disease are not well understood. Recent data suggests that variations in adipocyte cellular populations and subpopulations influence whole body metabolism. Particularly, an increased burden of adipocyte senescent cells (cells that are in a state of replicative arrest) have been implicated in metabolic diseases. To investigate the relationship between adipose molecular signatures and cellular senescence on metabolic outcomes, we will use a novel, high-throughput, high-resolution methodology called single nuclei RNA sequencing (SnRNA-seq) to develop a transcriptomic atlas of human adipose tissue and analyze molecular profiles before and after interventions of lifestyle vs. senolytic vs. placebo. We will recruit a cohort of older obese participants (≥65 years of age; BMI = 30-39.9 kg/m2; n = 72), and conduct a double-blinded, placebo-controlled, randomized trial in which we obtain adipose biopsies to analyze cellular/molecular profiling via snRNA-seq as it relates to phenotypic measures of insulin sensitivity, glucose tolerance, beta cell function, and hepatic lipid content compared to cohorts of younger lean (18-30 years of age; BMI = 18.5-24.9 kg/m2; n = 24) and older lean (≥65 years of age; BMI = 18.5-24.9 kg/m2; n = 24) participants. Older obese participants will be randomized to one of three groups for a 10-week period: lifestyle (diet- and exercise-induced weight loss of 8-10% of body mass), senolytic (dasatinib and quercetin), or placebo. Repeat adipose biopsies and metabolic testing will be analyzed before and after intervention to assess potential changes in gene expression and associated phenotypic measures. Inclusion criteria for the older obese participants are the following: ≥65 years of age, BMI 30-39.9 kg/m2, any sex, race and ethnic group, sedentary (≤1.5h of exercise per week), and nondiabetic. Exclusion criteria include history of diabetes, participation in structured exercise >1.5h per week, chronic inflammatory/neurologic/autoimmune/pulmonary disorders, GI or heart disease, use of anti-arrhythmic or weight altering medications, smoking/alcohol use, previous bariatric surgery, and use of/allergy to senolytic agents. Preliminary snRNA-seq analyses of adipose biopsies from our pilot study with non-diabetic participants identified cells with elevated expression of positive regulators of senescence (CDKN1A, CDKN2A, ARG2); notably, one subpopulation of senescent adipocytes, termed NewA1, was increased with higher BMI. Overall, the findings from this study may help us gain better understanding of the aging process and identify potential molecular targets for prevention of metabolic disease. Presentation: 6/1/2024

Efficacy and Safety of Cell-Assisted Acellular Adipose Matrix Transfer for Volume Retention and Regeneration Compared to Hyaluronic Acid Filler Injection.

Cell-assisted acellular adipose matrix (AAM) transfer is a novel technique for soft tissue volume restoration, where AAM acts as a scaffold for tissue proliferation and promotes host cell migration, vascularization, and adipogenesis. This study aimed to evaluate the efficacy and safety of in vivo cell-assisted AAM transfer compared to hyaluronic acid (HA) filler injection. Human adipose tissue was used to manufacture AAM, and murine adipose-derived stem cells (ASCs) were prepared. Nude mice were divided into four groups: AAM transfer (AT), ASC-assisted AAM transfer (CAT), HA filler injection (HI), and ASC-assisted HA filler injection (CHI). Eight weeks post-transfer, in vivo graft volume/weight, histology, and gene expression were analyzed to assess efficacy and safety. The AAM retained its three-dimensional scaffold structure without cellular components. AT/CAT showed lower volume retention than HA/CHA; however, CAT maintained a similar volume to HA. Histologically, adipogenesis and collagen formation were increased in AT/CAT compared to HA/CHA, with CAT showing the highest levels. CAT also demonstrated superior angiogenesis, adipogenesis, and gene expression (Vegf and Pparg), along with lower Il-6 expression, higher Il-10 expression, and reduced capsule formation, indicating better biocompatibility. Cell-assisted AAM transfer is a promising technique for volume retention and tissue regeneration, offering a safe and effective alternative to HA filler injections. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

In Vitro Treatment with Metformin Significantly Reduces Senescent B Cells Present in the Adipose Tissue of People with Obesity

BackgroundOur previous work has shown that senescent B cells accumulate in the human adipose tissue (AT) from people with obesity, where they express transcripts for markers associated with the senescence-associated secretory phenotype (SASP) and secrete multiple inflammatory mediators. These functions of AT-derived B cells are metabolically supported. ObjectivesTo show that Metformin (MET), a widely used hypoglycemic and antidiabetic drug, is able at least in vitro to decrease frequencies, secretory profile, and metabolic requirements of senescent B cells isolated from the AT from people with obesity. MethodsWe recruited adult females with obesity (n = 8, age 40 ± 2 y, BMI range: 33–42) undergoing breast reduction surgery, who donated their discarded subcutaneous AT. B cells from stromal vascular fractions isolated after collagenase digestion of the AT were evaluated after in vitro incubation with MET (1 mM × 106 B cells) or with a medium for the following measures. The expression of transcripts for SASP-associated markers (p16INK4a and p21CIP1/WAF1) measured by quantitative polymerase chain reaction (qPCR); secretion of inflammatory cytokines (TNF-α, IL-6, IFN-γ and IL-17A) measured by a Cytometric Bead Array); metabolic characteristics as identified by a glycolytic test and Seahorse technology, and by the expression of transcripts for glucose transporters and metabolic enzymes involved in glucose metabolic pathways, measured by qPCR. To examine differences between MET-treated compared with untreated groups, paired Student’s t tests (two-tailed) were employed. ResultsMET in vitro was able to reduce frequencies and numbers of senescent B cells, as identified by staining with β-galactosidase, as well as the secretion of inflammatory cytokines, the expression of transcripts for SASP, and metabolic markers that support intrinsic B cell inflammation. ConclusionsOur results provide evidence to support the beneficial effects of MET in reducing AT-related inflammation through its effects on senescent B cells.

A novel long non-coding RNA connects obesity to impaired adipocyte function

BackgroundLong non-coding RNAs (lncRNAs) can perform tasks of key relevance in fat cells, contributing, when defective, to the burden of obesity and its sequelae. Here, scrutiny of adipose tissue transcriptomes before and after bariatric surgery (GSE53378) granted identification of 496 lncRNAs linked to the obese phenotype. Only expression of linc-GALNTL6-4 displayed an average recovery over 2-fold and FDR-adjusted p-value <0.0001 after weight loss. The aim of the present study was to investigate the impact on adipocyte function and potential clinical value of impaired adipose linc-GALNTL6-4 in obese subjects. MethodsWe employed transcriptomic analysis of public dataset GSE199063, and cross validations in two large transversal cohorts to report evidence of a previously unknown association of adipose linc-GALNTL6-4 with obesity. We then performed functional analyses in human adipocyte cultures, genome-wide transcriptomics, and untargeted lipidomics in cell models of loss and gain of function to explore the molecular implications of its associations with obesity and weight loss. ResultsThe expression of linc-GALNTL6-4 in human adipose tissue is adipocyte-specific and co-segregates with obesity, being normalized upon weight loss. This co-segregation is demonstrated in two longitudinal weight loss studies and two cross-sectional samples. While compromised expression of linc-GALNTL6-4 in obese subjects is primarily due to the inflammatory component in the context of obesity, adipogenesis requires the transcriptional upregulation of linc-GALNTL6-4, the expression of which reaches an apex in terminally differentiated adipocytes. Functionally, we demonstrated that the knockdown of linc-GALNTL6-4 impairs adipogenesis, induces alterations in the lipidome, and leads to the downregulation of genes related to cell cycle, while propelling in adipocytes inflammation, impaired fatty acid metabolism, and altered gene expression patterns, including that of apolipoprotein C1 (APOC1). Conversely, the genetic gain of linc-GALNTL6-4 ameliorated differentiation and adipocyte phenotype, putatively by constraining APOC1, also contributing to the metabolism of triglycerides in adipose. ConclusionsCurrent data unveil the unforeseen connection of adipocyte-specific linc-GALNTL6-4 as a modulator of lipid homeostasis challenged by excessive body weight and meta-inflammation.

ACAT1/SOAT1 maintains adipogenic ability in preadipocytes by regulating cholesterol homeostasis.

Maintaining cholesterol homeostasis is critical for preserving adipocyte function during the progression of obesity. Despite this, the regulatory role of cholesterol esterification in governing adipocyte expandability has been understudied. Acyl-coenzyme A (CoA):cholesterol acyltransferase / Sterol O-acyltransferase 1 (ACAT1/SOAT1) is the dominant enzyme to synthesize cholesteryl ester in most tissues. Our previous study demonstrated that knockdown of either ACAT1 or ACAT2 impaired adipogenesis. However, the underlying mechanism of how ACAT1 mediates adipogenesis remains unclear. Here, we reported that ACAT1 is the dominant isoform in white adipose tissue of both humans and mice and knocking out ACAT1 reduced fat mass in mice. Furthermore, ACAT1-deficiency inhibited the early stage of adipogenesis via attenuating PPARγ pathway. Mechanistically, ACAT1 deficiency inhibited SREBP2-mediated cholesterol uptake and thus reduced intracellular and plasma membrane cholesterol level during adipogenesis. While replenishing cholesterol could rescue adipogenic master gene - Pparγ's transcription in ACAT1 deficient cells during adipogenesis. Finally, overexpression of catalytically functional ACAT1, not the catalytic-dead ACAT1, rescued cholesterol level and efficiently rescued the transcription of PPARγ, as well as the adipogenesis in ACAT1-deficient preadipocytes. In summary, our study revealed the indispensable role of ACAT1 in adipogenesis via regulating intracellular cholesterol homeostasis.

CNDP2: An Enzyme Linking Metabolism and Cardiovascular Diseases?

The heart requires a substantial amount of energy to function, utilising various substrates including lipids, glucose and lactate as energy sources. In times of increased stress, lactate becomes the primary energy source of the heart, but persistently elevated lactate levels are linked to poor patient outcomes and increased mortality. Recently, carnosine dipeptidase II (CNDP2) was discovered to catalyse the formation of Lac-Phe, an exercise-induced metabolite derived from lactate, which has been shown to suppress appetite in mice and reduce adipose tissue in humans. This review discusses CNDP2, including its role in lactate clearance, carnosine hydrolysis, oxidative stress regulation, and involvement in metabolite regulation. The association between CNDP2 and cardiometabolic and renal diseases is also explored, and knowledge gaps are highlighted. CNDP2 appears to be a complex participant in human physiological processes and disease, necessitating additional research to unveil its functions and potential therapeutic applications.

The effect of exogenous mitochondria in enhancing the survival and volume retention of transplanted fat tissue in a nude mice model

BackgroundDespite the pivotal role of fat grafting in plastic, reconstructive, and aesthetic surgery, inconsistent survival rates of transplanted adipose tissue, primarily due to early ischemic and hypoxic insults, remain a significant challenge. The infusion of healthy mitochondria has emerged as a promising intervention to support tissue recovery from ischemic, hypoxic, and other types of damages across various organ systems.ObjectivesThis study aims to evaluate the impact of supplementing human adipose tissue grafts with healthy exogenous mitochondria on their volume and mass retention rates when transplanted into the subcutaneous layers of nude mice. This approach seeks to improve and optimize fat grafting techniques.MethodsHuman adipose tissues were preconditioned with exogenous mitochondria (10 µg/mL), a combination of exogenous mitochondria and the inhibitor Dyngo-4a, Dyngo-4a alone, or PBS, and then transplanted into the subcutaneous tissue of 24 nude mice. Samples were harvested at 1 and 3 months post-transplantation for analysis of mass and volume retention. The structural morphology and integrity of the adipose tissues were assessed using Hematoxylin and Eosin (H&E) staining.ResultsMitochondrial preconditioning significantly enhanced the retention of mass and volume in fat grafts, demonstrating superior structural morphology and integrity compared to the control group.ConclusionsThis study highlights the potential of exogenous mitochondrial augmentation in fat transplantation to significantly improve fat graft survival, thereby optimizing the success of fat grafting procedures.

GDF3 promotes adipose tissue macrophage-mediated inflammation via altered chromatin accessibility during aging.

Age-related susceptibility to sepsis and endotoxemia is poorly defined, although hyperactivation of the immune system and the expansion of the visceral adipose as an immunological reservoir are underlying features. Macrophages from older organisms exhibit substantial changes, including chronic NLRP3 inflammasome activation, genomic remodeling and a dysfunctional, amplified inflammatory response upon new exposure to pathogen. However, the mechanisms by which old macrophages maintain their inflammatory phenotype during endotoxemia remains elusive. We previously identified Gdf3 , a TGFβ superfamily cytokine, as a top-regulated gene by age and the NLRP3 inflammasome in adipose tissue macrophages (ATMs). Here, we demonstrate that endotoxemia increases inflammatory (CD11c + ) ATMs in a Gdf3- dependent manner in old mice. Lifelong systemic or myeloid-specific deletion of Gdf3 leads to reduced endotoxemia- induced inflammation, with decreased CD11c + ATMs and inflammatory cytokines, and protection from hypothermia. Moreover, acute blockade of Gdf3 using JQ1, a BRD4 inhibitor, phenocopies old mice with lifelong Gdf3- deficiency. We show that GDF3 promotes the inflammatory phenotype in ATMs by phosphorylating SMAD2/3. Mechanistically, the differential chromatin landscape of ATMs from old mice with or without myeloid-driven Gdf3 indicates that GDF3- SMAD2/3 signaling axis shifts the chromatin accessibility of ATMs towards an inflammatory state during aging. Furthermore, pharmaceutical inhibition of SMAD3 with a specific inhibitor of SMAD3 (SIS3) mimics Gdf3 deletion. SIS3 reduces endotoxemia-mediated inflammation with fewer CD11c + ATMs and less severe hypothermia in old, but not young mice, as well as reduced mortality. In human adipose tissue, age positively correlates with GDF3 level, while inflammation correlates with pSMAD2/3 level. Overall, these results highlight the importance of GDF3-SMAD2/3 axis in driving inflammation in older organisms and identify this signaling axis as a promising therapeutic target for mitigating endotoxemia-related inflammation in the aged.

An optimized pipeline for high-throughput bulk RNA-Seq deconvolution illustrates the impact of obesity and weight loss on cell composition of human adipose tissue.

Katie Whytock ( Katie.Whytock@adventhealth.com ).

Combining evidence from human genetic and functional screens to identify pathways altering obesity and fat distribution.

Overall adiposity and body fat distribution are heritable traits associated with altered risk of cardiometabolic disease and mortality. Performing rare variant (minor allele frequency<1%) association testing using exome-sequencing data from 402,375 participants in the UK Biobank (UKB) for nine overall and tissue-specific fat distribution traits, we identified 19 genes where putatively damaging rare variation associated with at least one trait (Bonferroni-adjusted P<1.58×10-7) and 52 additional genes at FDR≤1% (P≤4.37×10-5). These 71 genes exhibited higher (P=3.58×10-18) common variant prioritisation scores than genes not significantly enriched for rare putatively damaging variation, with evidence of monotonic allelic series (dose-response relationships) among ultra-rare variants (minor allele count≤10) in 22 genes. Five of the 71 genes have cognate protein UKB Olink data available; all five associated (P<3.80×10-6) with three or more analysed traits. Combining rare and common variation evidence, allelic series and proteomics, we selected 17 genes for CRISPR knockout in human white adipose tissue cell lines. In three previously uncharacterised target genes, knockout increased (two-sided t-test P<0.05) lipid accumulation, a cellular phenotype relevant for fat mass traits, compared to Cas9-empty negative controls: COL5A3 (fold change [FC]=1.72, P=0.0028), EXOC7 (FC=1.35, P=0.0096), and TRIP10 (FC=1.39, P=0.0157); furthermore, knockout of SLTM resulted in reduced lipid accumulation (FC=0.51, P=1.91×10-4). Integrating across population-based genetic and in vitro functional evidence, we highlight therapeutic avenues for altering obesity and body fat distribution by modulating lipid accumulation.

Therapeutic potential of mesenchymal stromal cells on morphological parameters in the hippocampus of rats with brain ischemia-reperfusion modeling

Ischemic stroke is an extremely important pathology with high mortality, in which more than 50 % of patients with occlusion of the main vessels remain disabled, despite early reperfusion therapy by thrombolysis or thrombectomy. As part of the regenerative strategy, stem cell transplantation in ischemic stroke became a new impetus. Cell therapy with the use of mesenchymal stromal cells demonstrated encouraging results regarding endogenous mechanisms of neuroregeneration in response to ischemic damage to brain structures. The aim of the research is to study the influence of mesenchymal stromal cells of various genesis, lysate of mesenchymal stromal cells obtained from Wharton’s jelly umbilical cord and citicoline on the dynamics of morphological changes in the hippocampal CA1 region of rats with acute cerebral ischemia-reperfusion according to light microscopy and micromorphometry data. The experiment was carried out using 200 male Wistar rats, which were subjected to ischemia-reperfusion by reversible 20-minute bilateral occlusion of the internal carotid arteries. Animals with modeled pathology were intravenously transplanted with mesenchymal stromal cells of various genesis (from Wharton’s jelly of the human umbilical cord, human and rat adipose tissue), and rat embryonic fibroblasts, lysate of mesenchymal stromal cells and citicoline were injected. Histological analysis of rat brain sections was performed on the 7th and 14th day of the experiment. Statistical analysis was performed using “Statistica 6.0” (StatSoft® Snc, USA). The significance of differences was assessed using the Student’s t-test and the nonparametric Mann-Whitney U test. During the study, it was found that modeled ischemia-reperfusion in rats caused almost complete degeneration of the structure of the pyramidal layer of hippocampal CA1 region, gave uniformity to the structure of the radiant layer, infiltration of microglia, contributed to the disruption of the arrangement of apical dendrite bundles and narrowing of blood vessels as a result of perivascular edema. Also, the modeled pathology reduced the total number of neuronal nuclei in the hippocampal CA1 area, the overwhelming majority of which had signs of pathological changes. Transplantation of mesenchymal stromal cells of various origins, lysate of mesenchymal stromal cells and citicoline contributed to a significant increase in the number of neuronal nuclei in the hippocampal CA1 zone and nuclei that did not undergo pathological changes. The most positive effect was found in the transplantation of mesenchymal stromal cells from human Wharton’s jelly-derived cells. Thus, both in the subacute and recovery periods of ischemic stroke in rats, the transplantation of human Wharton’s jelly-derived mesenchymal stromal cells was significantly surpassed the reference drug citicoline in its ability to reduce the number of pathologically changed nuclei by 1.5 times (p&lt;0.05). At the same time, the number of pathologically unchanged nuclei significantly exceeded the number of nuclei with signs of karyorrhexis and karyopyknosis, so it would be advisable to use mesenchymal stromal cells of various genesis, lysate or citicoline in conditions of acute cerebral ischemia-reperfusion, taking into account their ability to reduce the volume of the infarct. In the future, an injectable drug will be created from the most effective culture of mesenchymal stromal cells in terms of cerebroprotective properties for cell therapy of patients with acute ischemic stroke.

The adipose tissue melanocortin 3 receptor is targeted by ghrelin and leptin and may be a therapeutic target in obesity

ObjectiveObesity is linked to perturbations in energy balance mechanisms, including ghrelin and leptin actions at the hypothalamic circuitry of neuropeptide Y (NPY) and melanocortin. However, information about the regulation of this system in the periphery is still scarce. Our objective was to study the regulation of the NPY/melanocortin system in the adipose tissue (AT) and evaluate its therapeutic potential for obesity and type 2 diabetes. MethodsThe expression of the NPY/melanocortin receptors’ levels was assessed in the visceral AT of individuals with obesity and altered metabolism. Protein levels of these receptors were evaluated in cultured adipocytes incubated with ghrelin (30 and 100 ng/mL) and leptin (1 and 10 nM) and in the AT of an animal model with a mutation in the leptin receptor (ZSF1 rat), to understand their regulation by leptin and ghrelin. The vertical sleeve gastrectomy animal model was used to evaluate the putative therapeutic potential of the NPY/melanocortin system. ResultsIn this study, we unravelled that leptin (1 nM and 10 nM) selectively reduced the levels of NPY5R and MC3R but no other NPYR/MCRs in cultured adipocytes. In turn, acylated ghrelin (100 ng/mL) significantly increased NPY1R, but the inhibition of its receptor also abrogates MC3R levels. However, in the Lepr-deficient ZSF1 rat, both NPY5R and MC3R levels were reduced, along with other NPYRs and MCRs, suggesting that leptin resistance negatively affects NPY and melanocortin signalling. In human adipose tissue, we found a downregulation of genes encoding the NPY and melanocortin receptors in the visceral AT of individuals with obesity and insulin resistance, being correlated with genes regulating metabolic activity. Additionally, diabetic obese rats submitted to vertical sleeve gastrectomy showed increased levels of NPY, melanocortin, ghrelin, and leptin receptors in the AT, including MC3R, suggesting it may constitute a therapeutic target in obesity. ConclusionsOur results suggest that the AT NPY/melanocortin system, particularly the MC3R, may be involved in the neuroendocrine regulation of adipocyte metabolism. Altogether, our work shows MC3R is under the control of the ghrelin/leptin duo, is reduced in patients with obesity and prediabetes, and may constitute a therapeutic target in obesity.