Adipocyte Inflammation Research Articles

Adipose tissue macrophages-derived exosomal MiR-500a-5p under high glucose promotes adipocytes inflammation by suppressing Nrf2 expression

BackgroundType 2 diabetes (T2DM) is a chronic metabolic disorder characterized by insulin resistance and chronic inflammation. Adipose tissue macrophages (ATMs), central players in mediating pro-inflammatory responses within adipose tissue, have been shown to influence insulin sensitivity through exosome secretion. While the role of macrophages-derived exosomal miRNA has been studied in various diseases, their pathogenic roles in T2DM, particularly ATMs-derived exosomal miRNA in adipose tissue inflammation, remain underexplored. ObjectivesThis study focuses specifically on T2DM, investigating the role of ATM-derived exosomal miRNAs in adipose tissue inflammation, a critical factor in the pathogenesis of T2DM. MethodsATM were isolated from visceral adipose tissues in patients with or without diabetes. Differentially expressed miRNAs in ATM-derived exosomes were predicted by high-throughput RNA sequencing. The RAW264.7 macrophages and 3T3-L1 preadipocytes was selected as a model system. Quantitative RT-PCR was used to assess miR-500a-5p expression. The direct binding of miR-500a-5p to Nrf2 mRNA 3′ UTR was verified by dual luciferase assay. ResultsMiR-500a-5p was also enriched in the exosomes of high-glucose-treated macrophages. Furthermore, these exosomes induced high expression of miR-500a-5p and activation of the NLRP3 inflammasome in adipocytes when co-cultured with them. Additionally, the reduction of miR-500a-5p expression in macrophages by using a miR-500a-5p inhibitor ameliorated the pro-inflammatory properties of the exosomes, and co-culturing these exosomes with adipocytes resulted in decreased expression of NLRP3 inflammasome-associated proteins in adipocytes. In contrast, induction of miR-500a-5p expression led to the opposite results. Moreover, the dual-luciferase assay confirmed that miR-500a-5p directly targeted the 3′ UTR of Nrf2 mRNA. Unlike miR-500a-5p, Nrf2 exhibited an anti-inflammatory response. ConclusionThe results indicate that ATM-derived exosomal miR-500a-5p promotes NLRP3 inflammasome activation and adipose tissue inflammation through down-regulation of Nrf2 in adipocytes.

Effect of Comparable Carbon Chain Length Short- and Branched-Chain Fatty Acids on Adipokine Secretion from Normoxic and Hypoxic Lipopolysaccharide-Stimulated 3T3-L1 Adipocytes.

Background: Microbial fermentation of non-digestible carbohydrates and/or protein produces short-chain fatty acids (SCFA), whereas branched-chain fatty acids (BCFA) are produced from protein fermentation. The effects of individual SCFA and BCFA of comparable carbon chain length on adipocyte inflammation have not been investigated. Objective: To compare the effects of SCFA and BCFA on inflammatory mediator secretion in an adipocyte cell culture model designed to recapitulate obesity-associated adipocyte inflammation under normoxic and hypoxic conditions. Methods: The 3T3-L1 adipocytes were cultured (24 h) without (Control, Con) and with 1 mmol/L of SCFA (butyric acid (But) or valeric acid (Val)) or 1 mmol/L of BCFA (isobutyric acid (IsoBut) or isovaleric acid (IsoVal)) and were unstimulated (cells alone, n = 6/treatment), or stimulated with 10 ng/mL lipopolysaccharide (LPS, inflammatory stimulus, n = 8/treatment) or 10 ng/mL LPS + 100 µmol/L of the hypoxia memetic cobalt chloride (LPS/CC, inflammatory/hypoxic stimulus, n = 8/treatment). Results: Compared to Con + LPS, But + LPS reduced secreted protein levels of interleukin (IL)-1β, IL-6, macrophage chemoattractant protein (MCP)-1/chemokine ligand (CCL)2, MCP3/CCL7, macrophage inflammatory protein (MIP)-1α/CCL3 and regulated upon activation, normal T cell expressed, and secreted (RANTES)/CCL5 and decreased intracellular protein expression of the ratio of phosphorylated to total signal transducer and activator of transcription 3 (STAT3) and nuclear factor kappa B (NFκB) p65 (p < 0.05). Val + LPS reduced IL-6 secretion and increased MCP-1/CCL2 secretion compared to Con + LPS and exhibited a different inflammatory mediator secretory profile from But + LPS (p < 0.05), indicating that individual SCFA exert individual effects. There were no differences in the secretory profile of the BCFA IsoBut + LPS and IsoVal + LPS (p > 0.05). Alternatively, under inflammatory hypoxic conditions (LPS/CC) Val, IsoVal, and IsoBut all increased secretion of IL-6, MCP-1/CCL2 and MIP-1α/CCL3 compared to Con (p < 0.05), whereas mediator secretion did not differ between But and Con (p > 0.05), indicating that the proinflammatory effects of SCFA and BCFA was attenuated by But. Interestingly, But + LPS/CC decreased STAT3 activation versus Con + LPS/CC (p < 0.05). Conclusions: The decreased secretion of inflammatory mediators that is attributable to But highlights the fact that individual SCFA and BCFA exert differential effects on adipocyte inflammation under normoxic and hypoxic conditions.

Therapeutic effects of FGF21 mimetic bFKB1 on MASH and atherosclerosis in Ldlr-/-.Leiden mice.

Fibroblast growth factor 21 (FGF21) is a promising target for treatment of obesity-associated diseases including metabolic dysfunction-associated steatohepatitis (MASH) and atherosclerosis. We evaluated the effects of the bispecific anti-FGF21-β klotho (KLB) agonist antibody bFKB1 in a preclinical model of MASH and atherosclerosis. Low-density lipoprotein receptor knockout (Ldlr-/-).Leiden mice received a high-fat diet for 20 weeks, followed by treatment with an isotype control antibody or bFKB1 for 12 weeks. Effects on plasma risk markers and (histo)pathology of liver, adipose tissue, and heart were evaluated alongside hepatic transcriptomics analysis. bFKB1 lowered body weight (-21%) and adipose tissue mass (-22%) without reducing food intake. The treatment also improved plasma insulin (-80%), cholesterol (-48%), triglycerides (-76%), alanine transaminase (ALT: -79%), and liver weight (-43%). Hepatic steatosis and inflammation were strongly reduced (macrovesicular steatosis -34%; microvesicular steatosis -100%; inflammation -74%) and while the total amount of fibrosis was not affected, bFKB1 did decrease new collagen formation (-49%). Correspondingly, hepatic transcriptomics and pathway analysis revealed the mechanistic background underlying these histological improvements, demonstrating broad inactivation of inflammatory and profibrotic transcriptional programs by bFKB1. In epididymal white adipose tissue, bFKB1 reduced adipocyte size (-16%) and inflammation (-52%) and induced browning, signified by increased uncoupling protein-1 (UCP1) protein expression (8.5-fold increase). In the vasculature, bFKB1 had anti-atherogenic effects, lowering total atherosclerotic lesion area (-38%). bFKB1 has strong beneficial metabolic effects associated with a reduction in hepatic steatosis, inflammation, and atherosclerosis. Analysis of new collagen formation and profibrotic transcriptional programs indicate that bFKB1 treatment may have antifibrotic potential in a longer treatment duration as well.

Impact of the local renin–angiotensin system in perivascular adipose tissue on vascular health and disease

Perivascular adipose tissue (PVAT) is found locally around blood vessels. It has the ability to release vasoactive chemicals, such as factors that relax and contract blood vessels. PVAT is now recognized as an endocrine organ with metabolic activity and as a “protagonist” for maintaining vascular homeostasis. Angiotensin II, a powerful vasoconstrictor of the renin–angiotensin system (RAS) that can increase blood pressure and vascular tone, is produced locally by PVAT. To mitigate the multiple vascular effects of angiotensin II, PVAT also generates molecules such as angiotensin (1–7), adiponectin, and nitric oxide. Reactive oxygen species and proinflammatory cytokines are produced in greater amounts when PVAT-mediated angiotensin II is present, resulting in endothelial dysfunction, inflammation, atherosclerosis, and other vascular disorders. The anticontractile and procontractile nature of PVAT is frequently disrupted in obese individuals, which increases the production of angiotensin II and decreases the production of anti-inflammatory and vasodilatory factors. These changes in turn exacerbate vascular inflammation, hypertension, and atherosclerosis. PVAT, which is crucial for maintaining vascular homeostasis, loses its anticontractile effect in obesity due to adipocyte hypertrophy, inflammation, and oxidative stress, exacerbating endothelial dysfunction. Overactive RAS in PVAT facilitates the migration and proliferation of vascular smooth muscle cells and atherosclerotic plaques, both of which accelerate the development of atherosclerosis. Targeting PVAT and the local RAS can offer therapeutic benefits in treating hypertension, atherosclerosis, and other vascular diseases. This review highlights the scientific underpinnings of the function of PVAT in regulating the autocrine and paracrine activities of vascular RAS constituents.

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.

MiR-10a regulates cell death and inflammation in adipose tissue of male mice with diet-induced obesity

ObjectiveAdipose tissue remodeling plays a critical role in obesity-induced metabolic dysfunction, but the underlying molecular mechanisms remain incompletely understood. This study investigates the role of miR-10a-5p in adipose tissue inflammation and metabolic dysfunction induced by a high fat diet (HFD). MethodsMale miR-10a knockout (KO) mice were fed a HFD to induce obesity for up to 16 weeks. RNA sequencing (RNA-seq) analysis was performed to profile mRNA expression and assess the effects of miR-10a-5p KO in gonadal white adipose tissue (gWAT). Additional analyses included immunoblotting, qPCR, histological examination, and validation of the miR-10a-5p target sequence using a dual-luciferase reporter assay. ResultsmiR-10a-5p was highly expressed in gWAT but decreased after 8 weeks of HFD feeding. Over the 16-week HFD period, miR-10a KO mice exhibited greater weight gain and reduced energy expenditure compared to wild-type (WT) controls. gWAT of miR-10a KO mice on a HFD showed an increased population of proinflammatory macrophages, elevated inflammation, and increased cell death, characterized by upregulated apoptosis and necrosis markers. This was also associated with increased triglyceride accumulation in the liver. Mechanistically, the proapoptotic gene Bcl2l11 was identified as a direct target of miR-10a-5p. Loss of miR-10a-5p led to BIM-mediated adipocyte death and inflammation, contributing to mitochondrial metabolic dysregulation, increased fibrosis marker expression, and the onset of inflammation in adipose tissue. ConclusionsThis study demonstrates the significant role of miR-10a-5p and its downstream target BIM in regulating adipocyte death during diet-induced obesity. This signaling pathway presents a potential therapeutic target for modulating obesity-induced inflammation and cell death in adipose tissue.

Bioprospection of rattlesnake venom peptide fractions with anti-adipose and anti-insulin resistance activity in vitro

Animal venoms are natural products that have served as a source of novel molecules that have inspired novel drugs for several diseases, including for metabolic diseases such as type-2 diabetes and obesity. From venoms, toxins such as exendin-4 (Heloderma suspectum) and crotamine (Crotalus durissus terrificus) have demonstrated their potential as treatments for obesity. Moreover, other toxins such as Phospholipases A2 and Disintegrins have shown their potential to modulate insulin secretion in vitro. This suggests an unexplored diversity of venom peptides with a potential anti-obesogenic in Mexican rattlesnake venoms. For that reason, this study explored the in vitro effect of Crotalus venom peptide-rich fractions on models for insulin resistance, adipocyte lipid accumulation, antioxidant activity, and inflammation process through nitric oxide production inhibition. Our results demonstrated that the peptide-rich fractions of C. aquilus, C. ravus, and C. scutulatus scutulatus were capable of reverting insulin resistance, enhancing glucose consumption to normal control; C. culminatus, C. molossus oaxacus, and C. polystictus diminished the lipid accumulation on adipocytes by 20%; C. aquilus, C. ravus, and C. s. salvini had the most significant cellular antioxidant activity, having nearly 80% of ROS inhibition. C. aquilus, C. pyrrhus, and C. s. salvini inhibited nitric oxide production by about 85%. We demonstrated the potential of these peptides from Crotalus venoms to develop novel drugs to treat type-2 diabetes and obesity. Moreover, we described for the first time that Crotalus venom peptide fractions have antioxidant and inflammatory properties in vitro models.

Calenduloside E Ameliorates Inflammatory Responses in Adipose Tissue via Sirtuin 2-NLRP3 Inflammasome Axis.

Obesity-related metabolic diseases are associated with a chronic inflammatory state. Calenduloside E (CE) is a triterpene saponin from sugar beet. In mouse models, CE reduced pro-inflammatory cytokines in white adipose tissue (WAT) and decreased macrophage infiltration of WAT. And CE inhibited pyroptosis in J774A.1 cells and WAT by inhibiting the activation of the nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 (NLRP3) inflammasome. Moreover, CE could trigger the activation of Sirtuin 2 (SIRT2), leading to a decrease in the acetylation of NLRP3, particularly at the K24 site. In addition, it has been shown that CE can reduce inflammation in adipocytes that have been induced by macrophage-conditioned medium. However, the selective SIRT2 inhibitor AGK2 hindered the beneficial effects of CE. In summary, CE has the capacity to impede NLRP3-mediated pyroptosis by triggering SIRT2 activity, thus positioning CE as a promising therapeutic avenue for combating obesity-related metabolic disorders.

Comparative Effects of Tumor Necrosis Factor Alpha, Lipopolysaccharide, and Palmitate on Mitochondrial Dysfunction in Cultured 3T3-L1 Adipocytes.

We have previously reported that dysregulated lipid metabolism and inflammation in 3T3-L1 adipocytes is attributed to tumor necrosis factor alpha (TNFα) rather than lipopolysaccharide (LPS) and palmitate (PA). In this study, we further compared the modulative effects of TNFα, LPS, and PA on mitochondrial function by treating 3T3-L1 adipocytes with TNFα (10 ng/mL), LPS (100 ng/mL), and PA (0.75 mM) individually or in combination for 24 h. Results showed a significant reduction in intracellular adenosine triphosphate (ATP) content, mitochondrial bioenergetics, total antioxidant capacity, and the mRNA expression of citrate synthase (Cs), sirtuin 3 (Sirt3), protein kinase AMP-activated catalytic subunit alpha 2 (Prkaa2), peroxisome proliferator-activated receptor gamma coactivator 1 alpha (Ppargc1α), nuclear respiratory factor 1 (Nrf1), and superoxide dismutase 1 (Sod1) in cells treated with TNFα individually or in combination with LPS and PA. Additionally, TNFα treatments decreased insulin receptor substrate 1 (Irs1), insulin receptor substrate 2 (Irs2), solute carrier family 2, facilitated glucose transporter member 4 (Slc2a4), and phosphoinositide 3 kinase regulatory subunit 1 (Pik3r1) mRNA expression. Treatment with LPS and PA alone, or in combination, did not affect the assessed metabolic parameters, while the combination of LPS and PA increased lipid peroxidation. These results show that TNFα but not LPS and PA dysregulate mitochondrial function, thus inducing oxidative stress and impaired insulin signaling in 3T3-L1 adipocytes. This suggests that TNFα treatment can be used as a basic in vitro model for studying the pathophysiology of mitochondrial dysfunction and related metabolic complications and screening potential anti-obesity therapeutics in 3T3-L1 adipocytes.

Adipocyte inflammation is the primary driver of hepatic insulin resistance in a human iPSC-based microphysiological system

Interactions between adipose tissue, liver and immune system are at the center of metabolic dysfunction-associated steatotic liver disease and type 2 diabetes. To address the need for an accurate in vitro model, we establish an interconnected microphysiological system (MPS) containing white adipocytes, hepatocytes and proinflammatory macrophages derived from isogenic human induced pluripotent stem cells. Using this MPS, we find that increasing the adipocyte-to-hepatocyte ratio moderately affects hepatocyte function, whereas macrophage-induced adipocyte inflammation causes lipid accumulation in hepatocytes and MPS-wide insulin resistance, corresponding to initiation of metabolic dysfunction-associated steatotic liver disease. We also use our MPS to identify and characterize pharmacological intervention strategies for hepatic steatosis and systemic insulin resistance and find that the glucagon-like peptide-1 receptor agonist semaglutide improves hepatocyte function by acting specifically on adipocytes. These results establish our MPS modeling the adipose tissue-liver axis as an alternative to animal models for mechanistic studies or drug discovery in metabolic diseases.

Inhibition of Adipocyte-Derived FABP4 Reduces Adipocyte Inflammation, Improves Angiogenesis, and Facilitates Wound Healing in Metabolic Dysfunctions

Dermal white adipose tissue may participate in the wound healing process. Obesity-mediated chronic low-grade inflammation impairs wound healing by suppressing vascularity. Given that fatty-acid-binding protein (FABP) 4 is upregulated in the skin tissue of obese animals, this study aimed to investigate the effects of FABP4 inhibition on wound healing in high-fat-diet (HFD)-induced metabolic dysfunction mice in vivo. The interaction between adipocyte-derived FABP4 and vascular endothelial cell function was also investigated. In HFD-induced metabolic dysfunction mice, FABP4 inhibition increased angiogenesis and facilitated wound healing with reduced wound inflammation. FABP4 inhibition not only attenuated systemic inflammation, decreased body weight, and reduced insulin resistance, but also improved the sizes of adipocytes and hypoxic conditions in dermal white adipose tissue. The in vitro hypoxia was used to induce adipocyte inflammation, and the supernatants from hypoxia-stimulated adipocytes impaired the function and angiogenetic capability of human dermal microvascular endothelial cells. Both of them were improved by FABP4 inhibition. Altogether, FABP4 inhibition reduced systemic and adipocyte inflammation, improved vascular endothelial cell function, and facilitated wound healing in metabolic dysfunctions. Given the complex involvement of wound healing, future studies may be required to validate FABP4 as a potential therapeutic target for wound repair in metabolic dysfunctions.

Interplay of FXN expression and lipolysis in white adipocytes plays a critical role in insulin sensitivity in Friedreich’s ataxia mouse model

Frataxin (FXN) is required for iron-sulfur cluster biogenesis, and its loss causes the early-onset neurodegenerative disease Friedreich ataxia (FRDA). Loss of FXN is a susceptibility factor in the development of diabetes, a common metabolic complication after myocardial hypertrophy in patients with FRDA. The underlying mechanism of FXN deficient-induced hyperglycemia in FRDA is, however, poorly understood. In this study, we confirmed that the FXN deficiency mouse model YG8R develops insulin resistance in elder individuals by disturbing lipid metabolic homeostasis in adipose tissues. Evaluation of lipolysis, lipogenesis, and fatty acid β-oxidation showed that lipolysis is most severely affected in white adipose tissues. Consistently, FXN deficiency significantly decreased expression of lipolytic genes encoding adipose triglyceride lipase (Atgl) and hormone-sensitive lipase (Hsl) resulting in adipocyte enlargement and inflammation. Lipolysis induction by fasting or cold exposure remarkably upregulated FXN expression, though FXN deficiency lessened the competency of lipolysis compared with the control or wild type mice. Moreover, we found that the impairment of lipolysis was present at a young age, a few months earlier than hyperglycemia and insulin resistance. Forskolin, an activator of lipolysis, or pioglitazone, an agonist of PPARγ, improved insulin sensitivity in FXN-deficient adipocytes or mice. We uncovered the interplay between FXN expression and lipolysis and found that impairment of lipolysis, particularly the white adipocytes, is an early event, likely, as a primary cause for insulin resistance in FRDA patients at later age.

Unveiling the Effects of Interval Resistance Training and Chlorella Vulgaris Supplementation on Meteorin-like Protein and Oxidative Stress in Obese Men

BackgroundDysregulation of adipocyte function occurs in obesity. Meteorin-like protein (Metrnl) is a newly discovered modulator of inflammation, metabolism, and differentiation of human adipocytes. The dietary supplement Chlorella Vulgaris (CV) reduces hyperlipidemia, hyperglycemia, and oxidative stress in clinical trials. ObjectivesTo explore the impact of 12 wks of interval resistance training (IRT) and CV supplementation on plasma levels of Metrnl and oxidative stress in males with obesity. MethodsForty-four obese men (BMI: 32.0 ± 1.5 kg/m2, weight: 101.1 ± 2.2 kg, age: 23–35 years) were randomly assigned into 4 groups (n = 11/group): control (CON), CV supplement (CV), IRT, and CV + IRT (CVIRT). The IRT was performed for 12 wks (3 sessions per week). The treatment consisted of a daily intake of CV (1800 mg capsule) or placebo capsules. Blood samples were collected 48 hours before and after the interventions to analyze biomedical measurements. ResultsThe IRT and CVIRT groups had elevations in plasma Metrnl, superoxide dismutase, and total antioxidant capacity levels (all P < 0.0001), and reductions in malondialdehyde (P < 0.0001). Supplementation with CV significantly reduced malondialdehyde (P < 0.001) and increased total antioxidant capacity (P < 0.0001) but failed to alter superoxide dismutase or Metrnl (P > 0.05). ConclusionsAlthough IRT and its combination with CV hold promise for improving Metrnl levels and oxidative status in obesity, combining IRT and CV do not yield greater benefits than IRT alone. Although standalone CV supplementation could favorably impact certain markers of oxidative stress, the effectiveness of CV supplementation appears to have a relatively limited effect across assessed biomarkers and requires further investigation.

LncRNA SNHG12 suppresses adipocyte inflammation and insulin resistance by regulating the HDAC9/Nrf2 axis.

Obesity is often associated with low-grade inflammation. The incidence of obesity has increased annually worldwide, which seriously affects human health. A previous study indicated that long noncoding RNA SNHG12 was downregulated in obesity. Nevertheless, the role of SNHG12 in obesity remains to be elucidated. In this study, qRT-PCR, western blot, and ELISA were utilized to examine the gene and protein expression. Flow cytometry was employed to investigate the M2 macrophage markers. RNA pull-down assay and RIP were utilized to confirm the interactions of SNHG12, hnRNPA1, and HDAC9. Eventually, a high-fat diet-fed mouse model was established for invivo studies. SNHG12 overexpression suppressed adipocyte inflammation and insulin resistance and promoted M2 polarization of macrophages that was caused by TNF-α treatment. SNHG12 interacted with hnRNPA1 to downregulate HDAC9 expression, which activated the Nrf2 signaling pathway. HDAC9 overexpression reversed the effect of SNHG12 overexpression on inflammatory response, insulin resistance, and M2 phenotype polarization. Overexpression of SNHG12 improved high-fat diet-fed mouse tissue inflammation. This study revealed the protective effect of SNHG12 against adipocyte inflammation and insulin resistance. This result further provides a new therapeutic target for preventing inflammation and insulin resistance in obesity.

Adipocyte-specific FAK deletion promotes pancreatic β-cell apoptosis via adipose inflammatory response to exacerbate diabetes mellitus.

White adipose tissue (WAT) has a key role in maintaining energy balance throughout the body, and their dysfunction take part in the regulation of diabetes mellitus. However, the internal regulatory mechanisms underlying are still unknown. We generated adipocyte-specific FAK KO (FAK-AKO) mice and investigated their phenotype. The cascade of adipocyte, macrophage in adipocyte tissues, and pancreatic β-cells were proposed in FAK-AKO mice and validated by cell line studies using 3T3-L1, Raw264.7 and Min6. The FAK-AKO mice exhibited glucose intolerance, reduced adipose tissue mass and increased apoptosis, lipolysis and inflammatory response in adipose tissue. We further demonstrate that adipocyte FAK deletion increases β cell apoptosis and inflammatory infiltrates into islets, which is potentiated if mice were treated with STZ. In the STZ-induced diabetes model, FAK AKO mice exhibit less serum insulin content and pancreatic β cell area. Moreover, serum pro-inflammatory factors increased and insulin levels decreased after glucose stimulation in FAK AKO mice. In a parallel vitro experiment, knockdown or inhibition of FAK during differentiation also increased apoptosis, lipolysis and inflammatory in 3T3-L1 adipocytes, whereas the opposite was observed upon overexpression of FAK. Moreover, coculturing LPS-treated RAW264.7 macrophages with knockdown FAK of 3T3-L1 adipocytes increased macrophage pro-inflammatory response. Furthermore, conditioned medium from above stimulated Min6 cells apoptosis (with or without STZ), whereas the opposite was observed upon overexpression of FAK. Mechanistically, FAK protein interact with TRAF6 in adipocytes and knockdown or inhibition of FAK activated TRAF6/TAK1/NF-κB signaling, which exacerbates inflammation of adipocytes themselves. Adipocyte FAK deletion promotes both adipocyte apoptosis and adipose tissue inflammation. Pro-inflammatory factors released by the FAK-null adipose tissue further trigger apoptosis in pancreatic islets induced by the administration of STZ, thereby exacerbating the diabetes mellitus. This study reveals a link between FAK-mediated adipose inflammation and diabetes mellitus, a mechanism that has not been previously recognized.

Role of Corn Peptide Powder in Lipopolysaccharide-Induced Inflammatory Responses in 3T3-L1 Adipocytes.

Corn peptide (CP) is a short, naturally occurring, and physiologically active peptide generated from corn-protease-catalyzed hydrolysis. CP plays a role in preventing obesity-related disorders, but its impact on reducing inflammation is unknown. Hence, this study examined the possible protective effects of corn peptide powder (CPP) against the harmful effects of lipopolysaccharide (LPS), with a particular emphasis on reducing oxidative damage and inflammation in adipocytes. Hence, mature 3T3-L1 adipocytes underwent exposure to 10 ng/mL LPS, with or without CPP (10 and 20 μg/mL). LPS stimulation increased reactive oxygen species and superoxide anion generation. However, this effect was reduced in a dose-dependent manner by pretreatment with CPP. CPP treatment elevated the mRNA expressions of the antioxidant enzymes manganese superoxide dismutase (mnSOD) and glutathione peroxidase 1 (Gpx1) while reducing the mRNA expressions of the cytosolic reactive oxygen species indicators p40 and p67 (NADPH oxidase 2). In addition, CPP inhibited the monocyte chemoattractant protein-1, tumor necrosis factor-alpha, Toll-like receptor 4, and nuclear factor kappa B mRNA expressions induced by LPS. These findings demonstrate that CPP may ameliorate adipocyte dysfunction by suppressing oxidative damage and inflammatory responses through a new mechanism known as Toll-like receptor 4/nuclear factor kappa B-mediated signaling.

Adipocyte inflammation and cardiometabolic disease

Adipocyte inflammation and cardiometabolic disease

Effect of Lampaya medicinalis Phil. (Verbenaceae) and Palmitic Acid on Insulin Signaling and Inflammatory Marker Expression in Human Adipocytes.

Aging and obesity are associated with insulin resistance (IR) and low-grade inflammation. Molecularly, IR is characterized by a reduction in glucose uptake and insulin signaling (IRS-1/Akt/AS160 pathway), while inflammation may result from upregulated NF-κB pathway after low Tyr-IκBα phosphorylation. Upregulated phosphatase activity of PTP1B is associated with impaired insulin signaling and increased inflammation. Plasma levels of palmitic acid (PA) are elevated in obesity, triggering inflammation and disruption of insulin signaling. Traditional medicine in Northern Chile uses oral infusions of Lampaya medicinalis Phil. (Verbenaceae) to treat inflammatory conditions. Significant amounts of flavonoids are found in the hydroethanolic extract of Lampaya (HEL), which may account for its biological activity. The aim of this work was to study the effect of HEL and PA on insulin signaling and glucose uptake as well as inflammatory marker expression in human adipocytes. We studied HEL effects on PA-induced impairment on insulin signaling, glucose uptake and inflammatory marker content in human SW872 adipocytes. HEL cytotoxicity was assessed in adipocytes at different concentrations (0.01 to 10 g/mL). Adipocytes were incubated or not with PA (0.4 mM, 24 h) with or without HEL (2 h pre-incubation), and then stimulated with insulin (10 min, 100 mM) or a vehicle. Phospho-IRS-1, phospho-Akt, phospho-AS160, phospho-NF-κB and phospho-IκBα, as well as protein levels of PTP1B, were assessed using Western blotting, and glucose uptake was evaluated using the 2-NBDG analogue. At the assessed HEL concentrations, no cytotoxic effects were observed. PA decreased insulin-stimulated phospho-Akt and glucose uptake, while co-treatment with HEL increased such markers. PA decreased phospho-IRS-1 and phospho-Tyr-IκBα. On the other hand, incubation with HEL+PA decreased phospho-AS160 and phospho-NF-κB compared with cells treated with PA alone. Our results suggest a beneficial effect of HEL by improving PA-induced impairment on molecular markers of insulin signaling, glucose uptake and inflammation in adipocytes. Further studies are necessary to elucidate whether lampaya may constitute a preventive strategy for people whose circulating PA levels contribute to IR and inflammation during aging and obesity.

G protein-coupled receptor 146: new insights from genetics and model systems.

Atherosclerotic cardiovascular diseases continue to be a significant global cause of death. Despite the availability of efficient treatments, there is an ongoing need for innovative strategies to lower lipid levels, especially for individuals experiencing refractory dyslipidemias or intolerable adverse effects. Based on human genetic findings and on mouse studies, the G protein-coupled receptor 146 (GPR146) emerges as a promising target against hypercholesterolemia and atherosclerosis. The present review aims at providing a thorough summary of the latest information acquired regarding GPR146, encompassing genetic evidence, functional insights, and its broader implications for cardiometabolic health. Human genetic studies uncovered associations between GPR146 variants, plasma lipid levels and metabolic parameters. Additionally, GPR146's influence extends beyond lipid regulation, impacting adipocyte differentiation, lipolysis, and inflammation pathways. Despite GPR146's orphan status, ongoing efforts to deorphanize it, suggest a potential ligand with downstream effects involving Gαi coupling. Here, we outline and deliberate on recent progress focused on: enhancing comprehension of the effects of inhibiting GPR146 in humans through genetic instruments, evaluating the extra-hepatic functions of GPR146, and discovering its natural ligand(s). Grasping these biological parameters and mechanisms is crucial in the exploration of GPR146 as a prospective therapeutic target.

Abstract A090: An inflammatory adipose microenvironment promotes ovarian cancer tumor growth and cisplatin resistance

Abstract Epithelial ovarian cancer (EOC) commonly targets the omentum, an adipocyte rich organ of the peritoneum. Omental adipocytes have been shown to promote EOC development and chemoresistance via transfer of free fatty acids (FFAs) and the induction of bi-directional metabolic changes. Furthermore, obesity and adiposity are risk factors for EOC incidence and prognosis. The metastatic peritoneal tumor microenvironment (TME) is highly inflamed, while obesity is often characterized by chronic inflammation of adipose tissue and hyperlipidemia. Given that inflammation of adipocytes is associated with increased release of FFAs, we hypothesized that acute inflammation in the ovarian metastatic TME exacerbates pro-tumorigenic effects of cancer-associated adipocytes. Using a three-dimensional transwell co-culture model, we explore the impact of inflamed adipocytes on EOC activity. Adipocytes generated from human adipose-derived stem cells were inflamed with 100ng/ml TNFα and cultured alongside tumor spheroids generated from EOC cell lines. Cytokine abundance in serum samples from ovarian cancer patients undergoing cisplatin treatment were also analyzed. We found that inflammation of adipocytes increased cellular lipolysis and release of FFAs, as well as inducing de-differentiation and loss of lipid droplets. Upon co-culture with inflamed adipocytes, EOC cells displayed increased proliferation in 2D monolayer and 3D spheroid cultures. Transfer of FFAs from adipocytes to cancer cells was visualized and quantified using a fluorescent fatty acid analog via confocal microscopy and flow cytometry. Co-culture induced expression of fatty acid chaperone protein FABP4 in EOC cell lines, while blocking fatty acid metabolism in cancer cells reversed pro-tumor effects of adipocytes. To understand signaling mechanisms generating bi-directional phenotypic changes, cytokine content of secretome of co-cultures was assessed by Luminex. IL-6 and IL-8 were highly abundant in co-cultures, and increased expression was confirmed by qPCR. Treatment of EOC cell lines with recombinant IL-6 and IL-8 induced increased uptake of FFAs and blocking of IL-6 and IL-8 signaling reversed pro-cancer effects of adipocytes. Serum samples from patients undergoing cisplatin therapy were analyzed and IL-6 and IL-8 levels were found to be associated with resistance to therapy. To further investigate the impact of inflamed adipocyte signaling on therapeutic resistance, co-culture were treated with cisplatin and tumor spheroids were found to be highly resistant in the presence of inflamed adipocytes. STAT3 activity is known to be upregulated by both IL-6 and IL-8 and we found that STAT3 expression was increased in co-cultures. Knockdown of STAT3 in EOC reversed the chemoprotective effects of inflamed adipocytes. These data suggest an important role for inflammation of adipose tissue in the development of therapeutic resistance in EOC and highlight a potential mechanism linking clinically observed associations between obesity and ovarian cancer risk. Citation Format: Michael E. Williams, David Howard, Deyarina Gonzalez, Francesca Taraballi. An inflammatory adipose microenvironment promotes ovarian cancer tumor growth and cisplatin resistance [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A090.