High-fat Diet Feeding Research Articles

Effects of high-fat diet on the morphology and function of the thyroid gland and glycolipid metabolism in thyroid clock gene Bmal1 knockout mice

Objective: To investigate the changes in thyroid morphology and function in mice with thyroid-specific knockout of the clock gene Bmal1 under high-fat diet (HFD), and to examine its effects on glycolipid metabolism in mice. Methods: Construct a mouse model with specific knockout of the Bmal1 gene in the thyroid (T-Bmal1-/-) (knockout group, n=10), and use Bmal1flox/flox mice without thyroid peroxidase-cyclization recombination enzyme (T-Bmal1+/+) as the control group (non-knockout group, n=10). The mice were fed until 6 weeks (body weight 20-23 g), and then use the random number table method to evenly divide each group of mice into two subgroups. They were then fed either with normal diet (ND) or (HFD), resulting in four final groups: ND non-knockout group, HFD non-knockout group, ND knockout group, and HFD knockout group, with 5 mice in each group. From the 6th week onwards, the body weights of the mice were measured for 10 consecutive weeks. On the first day of the 14th week, the intraperitoneal glucose tolerance test (IPGTT) was conducted, and on the first day of the 15th week, the intraperitoneal insulin tolerance test (IPITT) was performed. On the first day of the 16th week after the mice were born, blood samples (0.2 ml) were taken from the eyes under anesthesia at 7∶00, 13:00, 19:00, and 1∶00 the next day, and the thyroid, liver, kidneys, spleen, inguinal white adipose tissue, and scapular brown adipose tissue were rapidly removed. Thyroid tissue morphology, thyroid function indexes, thyroid clock genes and thyroid hormone synthesis and secretion related genes expression, body weight, IPGTT and IPITT area under the curve (AUC) and lipid levels were detected and compared among all groups. Results: There was no significant difference in the number of thyroid follicles, the area of thyroid follicles and the height of thyroid follicle cavity between ND knockout group and ND non-knockout group (all P>0.05), but the height of thyroid follicle cavity in HFD knockout group was lower than that in HFD knockout group [(25.8±1.6) vs (54.4±9.5) μm, P=0.002]. The level of serum T4 in knockout group after ND or HFD feeding was higher than that in non-knockout group (all P<0.05). There was no significant difference in the mRNA expression level of sodium iodine transporter between ND knockout group and ND non-knockout group (P=0.550), but the mRNA expression level of sodium iodine transporter in HFD knockout group was higher than that in HFD non-knockout group [0.67±0.27 vs 0.20±0.09, P=0.006].There was no significant difference in weight gain and groin white fat weight between ND knockout group and ND non-knockout group (both P<0.05), but weight gain and groin white fat tissue weight in HFD knockout group were lower than those in HFD knockout group (both P<0.05). The IPGTT results showed no statistically significant difference in AUC between the ND knockout and ND non-knockout groups (P=0.226), but the HFD knockout group had a smaller AUC than the HFD non-knockout group (P=0.008). The IPITT revealed that the AUC of the ND knockout group was smaller than that of the ND non-knockout group (P=0.047). Lipid profiles were similar between the ND knockout and ND non-knockout groups (all P>0.05), but the HFD knockout group had lower levels of total cholesterol and high-density lipoprotein cholesterol than the HFD non-knockout group (both P<0.05). Conclusion: Thyroid-specific knockout of the clock gene Bmal1 can affect thyroid hormone levels and glycolipid metabolism in mice, with more pronounced effects after HFD feeding.

Sex differentially affects pro-inflammatory cell subsets in adipose tissue depots in a diet induced obesity model

Obesity is a growing pandemic that increases the risk for cardiovascular diseases, type 2 diabetes, and particularly in women also the risk of cancer and neurodegenerative disorders such as dementia and multiple sclerosis. Preclinical studies on obesity focus on male mice as they gain bodyweight faster and show a clear pro-inflammatory phenotype. Here, using male and female mice, we induced obesity by feeding a high fat diet (HFD), and compared adipose tissue (AT) inflammation at the same adiposity stage (% AT/bodyweight) between both sexes. Doing so, we identified that female mice show an increase in the number of pro-inflammatory immune cells in the visceral AT at a lower adiposity stage than male mice, but the effect of HFD is diminished with higher adiposity. Interestingly, only female mice showed an increase in immune cells in the subcutaneous AT after HFD feeding. Nonetheless, we found that pro-inflammatory cytokines in blood plasma mirror the inflammatory stage of the visceral AT in both male and female mice. Uniquely in male mice, myeloid cells in the visceral AT showed a higher inflammasome activation upon HFD. In summary, we showed that adiposity differentially affects immune cells in fat depots based on sex.

Maternal high-fat diet orchestrates offspring hepatic cholesterol metabolism via MEF2A hypermethylation-mediated CYP7A1 suppression

BackgroundMaternal overnutrition, prevalent among women of childbearing age, significantly impacts offspring health throughout their lifetime. While DNA methylation of metabolic-related genes mediates the transmission of detrimental effects from maternal high-fat diet (HFD), its role in programming hepatic cholesterol metabolism in offspring, particularly during weaning, remains elusive.MethodsFemale C57BL/6 J mice were administered a HFD or control diet, before and during, gestation and lactation. Hepatic cholesterol metabolism genes in the liver of offspring were evaluated in terms of their expression. The potential regulator of cholesterol metabolism in the offspring’s liver was identified, and the function of the targeted transcription factor was evaluated through in vitro experiments. The methylation level of the target transcription factor was assessed using the MassARRAY EpiTYPER platform. To determine whether transcription factor expression is influenced by DNA methylation, in vitro experiments were performed using 5-azacitidine and Lucia luciferase activity assays.ResultsHere, we demonstrate that maternal HFD results in higher body weight and hypercholesterolemia in the offspring as early as weaning age. Maternal HFD feeding exacerbates hepatic cholesterol accumulation in offspring primarily by inhibiting cholesterol elimination to bile acids, with a significant decrease of hepatic cholesterol 7α-hydroxylase (CYP7A1). RNA-seq analysis identified myocyte enhancer factor 2A (MEF2A) as a key transcription factor in the offspring liver, which was significantly downregulated in offspring of HFD-fed dams. MEF2A knockdown led to CYP7A1 downregulation and lipid accumulation in HepG2 cells, while MEF2A overexpression reversed this effect. Dual luciferase reporter assays confirmed direct modulation of CYP7A1 transcription by MEF2A. Furthermore, the reduced MEF2A expression was attributed to DNA hypermethylation in the Mef2a promoter region. This epigenetic modification manifested as early as the fetal stage.ConclusionsThis study provides novel insights into how maternal HFD orchestrates hepatic cholesterol metabolism via MEF2A hypermethylation-mediated CYP7A1 suppression in offspring at weaning.

Effects of Bifidobacterium and rosuvastatin on metabolic-associated fatty liver disease via the gut–liver axis

Background/aimsResearch has indicated that treatment with rosuvastatin can improve liver pathology in metabolic-associated fatty liver disease (MAFLD) patients and that treatment with Bifidobacterium can improve MAFLD. Therefore, the effects of Bifidobacterium, rosuvastatin, and their combination on related indices in a rat model of diet-induced MAFLD need to be investigated.MethodsForty rats were divided into five groups: the normal diet group (N), high-fat diet (HFD) model group (M), HFD + probiotic group (P), HFD + statin group (S), and HFD + probiotic + statin group (P-S). To establish the MAFLD model, the rats in Groups M, P, S, and P-S were fed a HFD for 8 weeks. The treatments included saline in Group N and either Bifidobacterium, rosuvastatin, or their combination in Groups P, S, and P-S by intragastrical gavage. After 4 weeks of intervention, the rats were euthanized, and samples were harvested to analyze gastrointestinal motility and liver function, pathological changes, inflammatory cytokine production, and the expression of proteins in key signaling pathways.ResultsHFD feeding significantly increased the body weight, liver index, and insulin resistance (IR) index of the rats, indicating that the MAFLD model was successfully induced. Bifidobacterium reduced the liver of MAFLD rats, while Bifidobacterium with Rosuvastatin decreased the liver index, IR index, and levels of aspartate aminotransferase and alanine aminotransferase in MAFLD rats. The MAFLD model showed altered expression of proteins in signaling pathways that regulate inflammation, increased production of inflammatory cytokines, an elevated MAFLD activity score (MAS), and pathological changes in the liver. The MAFLD model also showed reduced relative counts of intestinal neurons and enteric glial cells (EGCs), altered secretion of gastrointestinal hormones, and slowed gastrointestinal emptying. Bifidobacterium, rosuvastatin, or their combination inhibited these various changes. HFD feeding changed the rats’ gut microbiota, and the tested treatments inhibited these changes. These results suggest that the gastrointestinal motility disorder and abnormal liver function in MAFLD rats may be related to a reduction in Escherichia-Shigella bacteria and an increase in Asticcacaulis bacteria in the gut microbiota and that the improvement in liver function induced by Bifidobacterium plus rosuvastatin may be related to increases in Sphingomonas and Odoribacter bacteria and a decrease in Turicibacter bacteria in the gut microbiota.ConclusionsThe combined use of Bifidobacterium and rosuvastatin could better regulate the gut microbiota of MAFLD model rats, promote gastrointestinal emptying, and improve liver pathology and function than single treatment with Bifidobacterium or rosuvastatin. This provides a better strategy for the treatment of MAFLD.

Swimming combined with corn peptide counteracts high-fat diet-induced obesity through rescuing imbalanced gut flora

To investigate the effects of swimming and corn peptide on counteracting obesity of high-fat diet (HFD)-induced mice and uncover the underlying mechanisms through analyzing the compositions and structure of gut flora and corresponding metabolites, an obesity model was established using C57BL/6 mice with HFD feeding. The obese mice underwent swimming intervention, oral administration of corn peptide, or a combination of both interventions for 8 consecutive weeks. After the interventions, blood lipid levels were measured, and fecal samples were collected for 16S rDNA sequencing and broad-targeted metabolomics analysis. Metabolic pathway enrichment analysis was performed using the MetaboAnalyst software, and the correlations between differential phenotypes, gut flora, and metabolites were analyzed using the Spearman method. The combination of swimming and corn peptide interventions effectively reduced hyperlipidemia in obese mice. Swimming combined with corn peptide intervention partially reversed the dysbiosis of gut microbiota in obese mice. This included an increase in the relative abundance of beneficial bacteria such as Prevotellaceae and Oscillospiraceae, and a decrease in the relative abundance of Alloprevotella. Additionally, all three interventions improved four key metabolic pathways: glycerophospholipid metabolism, pyrimidine metabolism, tyrosine metabolism, and folate synthesis. Therefore, the combinatorial intervention of swimming and corn peptide can at least partially ameliorate HFD-induced gut microbiota dysbiosis and corresponding metabolic changes, promote energy metabolism, and contribute to body weight control and lipid-lowering effects in obese mice.

Jia Wei Qingxin Lotus Seed Drink ameliorates epithelial mesenchymal transition injury in diabetic kidney disease via inhibition of JMJD1C/SP1/ZEB1 signaling pathway

BackgroundDiabetic kidney disease (DKD) is one of the most common microvascular complications in patients with diabetes mellitus. In this condition, renal tubular epithelial mesenchymal transition (EMT) is an important factor accelerating the progression of DKD and a major cause of renal fibrosis and end-stage renal disease. However, the therapeutic effect is unsatisfactory because of the lack of effective drugs. Jia Wei Qingxin Lotus Seed Drink (QISD) is a traditional Chinese medicine compound formula that has shown to be effective in the clinical treatment of DKD. However, the potential of QISD in DKD-EMT treatment has yet to be fully explored. PurposeThis study aimed to investigate the role of QISD in ameliorating DKD-EMT injury and its mechanism. MethodsThe active ingredients of QISD were identified via ultra-performance liquid chromatography-mass spectrometry/mass spectrometry (UHPLC-MS/MS). A DKD mouse model was constructed by high-fat diet feeding and intraperitoneal injection of STZ (60 mg/kg), and QISD (14.46, 28.92, and 57.84 g/kg/day) was administered by gavage for 12 consecutive weeks. Dapagliflozin (1 mg/kg/d) was used as a positive control. Renal pathological damage was observed by HE, PAS, and Masson staining. The expression levels of EMT-related proteins and pathway proteins were detected via immunohistochemistry, RT-qPCR, and western blot. In in vitro experiments, EMT injury was induced in human kidney tubular epithelial cells (HK-2) by using lipopolysaccharide (LPS). A combination of CCK8 assay, wound healing assay, small-molecule inhibitor intervention, and overexpression lentiviral transfection was used to investigate the effects of QISD on cell migration ability, adhesion ability, fibrotic factor formation, and mesenchymal properties. ResultsAnimal experiments showed that QISD improved blood glucose, body weight, symptoms of excessive drinking and eating, and renal pathological injury in mice, reduced extracellular matrix deposition, delayed renal EMT injury, and inhibited the activation of the histone demethylase JMJD1C. UHPLC-MS/MS and molecular docking indicated that baicalin, wogonoside, oroxylin A-7-O-β-D-glucuronide, and glulisine A found in QISD could bind to JMJD1C. The ameliorating effect of QISD on DKD-EMT injury might be related to JMJD1C. The improvement of DKD-EMT injury by QISD was accompanied by the reduction of SP1 and ZEB1 expression. The SP1 overexpression not only reversed the therapeutic effect of JIB-04, an inhibitor of JMJD1C, on DKD-EMT but also exacerbated the expression of ZEB1 and downstream EMT-related factors. Thus, QISD might affect the expression of the epithelial marker E-cadherin by inhibiting the JMJD1C/SP1/ZEB1 signaling pathway, consequently preventing the transformation of epithelial cells to mesenchymal cells and ameliorating DKD-EMT injury. ConclusionThis study was the first to demonstrate that QISD might ameliorate DKD-EMT injury by inhibiting the JMJD1C/SP1/ZEB1 signaling pathway. These findings provide strong pharmacologic evidence for the clinical use of QISD in the treatment of DKD.

Simultaneous treatment with palm-LEAP2(1-14) and feeding high-fat diet attenuates liver lipid metabolism but not obesity: Sign of selective resistance to palm-LEAP2(1-14).

Liver-enriched antimicrobial peptide 2 (LEAP2) is a natural antagonist/inverse agonist of ghrelin receptor GHSR. Its truncated palmitoylated analog palm-LEAP2(1-14) promised anti-obesity properties because it exhibited favourable stability and an acute anorexigenic effect in our previous studies. Here we demonstrate desirable palm-LEAP2(1-14) pharmacokinetics, with significant levels of the peptide persisting in mouse blood 3 hours after its subcutaneous administration. Palm-LEAP2(1-14) reduced ghrelin-induced c-Fos immunoreactivity in arcuate nucleus and area postrema, in line with previously described silencing of ghrelin orexigenic effect. In spite of this, anti-obesity effect was not reached by two-week palm-LEAP2(1-14) treatment in mice with diet-induced obesity. Similarly, palm-LEAP2(1-14) administered simultaneously with high-fat diet feeding for 8 weeks did not protect mice from development of obesity and related biochemical changes. However, palm-LEAP2(1-14) kept its ability to attenuate liver de novo lipogenesis, and prominently lowered liver gene expression of nuclear receptors PPARG, SREBF1 and PPARA, and also expression of lipogenic and lipolytic enzymes. In our recent study, we described a high-fat diet-induced ghrelin resistance, reversible by switch to standard diet, followed by resistance to the acute anorexigenic effects of palm-LEAP2(1-14). Here we conclude that this resistance to palm-LEAP2(1-14) in obesity is probably selective and does not concern its ability to inhibit liver lipid metabolism.

Donepezil improves skeletal muscle insulin resistance in obese mice via the AMPK/FGF21-mediated suppression of inflammation and ferroptosis.

Donepezil has traditionally been used in Alzheimer's disease treatment and is known for its ability to alleviate neural inflammation and apoptosis. However, its impact on insulin signaling remains unexplored. This study sought to elucidate the novel role of donepezil in mitigating skeletal muscle insulin resistance under hyperlipidemic conditions. Western blot analysis was used to assess the expression of various proteins of interest, whereas a glucose uptake assay was performed in skeletal muscle cells via commercially available kits. An in vitro model of obesity was developed using palmitate. These in vitro findings were corroborated in vivo via insulin resistance models established through high-fat diet (HFD) feeding in mice. Intraperitoneal glucose tolerance tests and insulin tolerance tests were performed on the experimental mice. The results revealed that donepezil treatment improved insulin signaling and inflammation in palmitate-treated C2C12 myocytes and the skeletal muscle of HFD-fed mice. Notably, donepezil treatment augmented FGF21 expression and AMPK phosphorylation in the myocytes and skeletal muscle of HFD-fed mice. Knockdown of FGF21 or AMPK via siRNA reversed the effects of donepezil on insulin signaling and inflammation in cultured myocytes. We also found that donepezil ameliorated skeletal muscle insulin resistance via the FGF21-mediated suppression of ferroptosis under hyperlipidemic conditions. These findings suggest that donepezil enhances the FGF21/AMPK axis, thereby mitigating inflammation and insulin resistance in skeletal muscle. This study introduces a novel therapeutic approach for treating Alzheimer's disease patients with insulin resistance.

Finerenone attenuates downregulation of the kidney GLP-1 receptor and glucagon receptor and cardiac GIP receptor in mice with comorbid diabetes

BackgroundSeveral new treatments have recently been shown to have heart and kidney protective benefits in people with diabetes. Because these treatments were developed in parallel, it is unclear how the different molecular pathways affected by the therapies may overlap. Here, we examined the effects of the mineralocorticoid receptor antagonist finerenone in mice with comorbid diabetes, focusing on the regulation of expression of the glucagon-like peptide-1 receptor (GLP-1R), gastric inhibitory polypeptide receptor (GIPR) and glucagon receptor (GCGR), which are targets of approved or investigational therapies in diabetes.MethodsMale C57BL/6J mice were fed a high fat diet for 26 weeks. Twelve weeks into the high fat diet feeding period, mice received an intraperitoneal injection of streptozotocin before being followed for the remaining 14 weeks (DMHFD mice). After 26 weeks, mice were fed a high fat diet containing finerenone (100 mg/kg diet) or high fat diet alone for a further 2 weeks. Cell culture experiments were performed in primary vascular smooth muscle cells (VSMCs), NRK-49 F fibroblasts, HK-2 cells, and MDCK cells.ResultsDMHFD mice developed albuminuria, glomerular mesangial expansion, and diastolic dysfunction (decreased E/A ratio). Glp1r and Gcgr were predominantly expressed in arteriolar VSMCs and distal nephron structures of mouse kidneys respectively, whereas Gipr was the predominant of the three transcripts in mouse hearts. Kidney Glp1r and Gcgr and cardiac Gipr mRNA levels were reduced in DMHFD mice and this reduction was negated or attenuated with finerenone. Mechanistically, finerenone attenuated upregulation of the profibrotic growth factor Ccn2 in DMHFD kidneys, whereas recombinant CCN2 downregulated Glp1r and Gcgr in VSMCs and MDCK cells respectively.ConclusionsThrough its anti-fibrotic actions, finerenone reverses Glp1r and Gcgr downregulation in the diabetic kidney. Both finerenone and GLP-1R agonists have proven cardiorenal benefits, whereas receptor co-agonists are approved or under development. The current findings provide preclinical rationale for the combined use of finerenone with the GLP-1R agonist family. They also provide mechanism of action insights into the potential benefit of finerenone in people with diabetes for whom GLP-1R agonists or co-agonists may not be indicated.

Butyrate attenuates high-fat diet-induced glomerulopathy through GPR43-Sirt3 pathway.

The incidence of obesity-related glomerulopathy (ORG) is rising worldwide with very limited treatment methods. Paralleled with the gut–kidney axis theory, the beneficial effects of butyrate, one of the short-chain fatty acids (SCFA)produced by gut microbiota, on metabolism and certain kidney diseases have gained growing attention. However, the effects of butyrate on ORG and its underlying mechanism are largely unexplored. In this study, a mice model of ORG was established with a high-fat diet feeding for 16 weeks, and sodium butyrate treatment was initiated at the 8th week. Podocyte injury, oxidative stress and mitochondria function were evaluated in mice kidney and validated in vitro in palmitic acid-treated-mouse podocyte cell lines. Further, the molecular mechanisms of butyrate on podocytes were explored. Compared with controls, sodium butyrate treatment alleviated kidney injuries and renal oxidative stress in high-fat diet-fed mice. In mouse podocyte cell lines, butyrate ameliorated palmitic acid-induced podocyte damage and helped maintain the structure and function of the mitochondria. Moreover, the effects of butyrate on podocytes were mediated via the GPR43-Sirt3 signal pathway, as evidenced by the diminished effects of butyrate with the intervention of GPR43 or Sirt3 inhibitors. In summary, we conclude that butyrate has therapeutic potential for the treatment of ORG. It attenuates high-fat diet-induced ORG and podocyte injuries through the activation of the GPR43-Sirt3 signalling pathway.

Increase in body weight is lowered when mice received fecal microbiota transfer from donor mice treated with the AT1 receptor antagonist telmisartan.

Treatment of rodents with the AT1 blocker (ARB) telmisartan (TEL) has an anti-adipose effect. Among other mechanisms, we also have attributed the anti-adipose action to diet-independent alterations in gut microbiota. Thus, we aimed here to confirm this mechanism by using the fecal microbiota transfer (FMT) approach. Seven weeks after initiating a high-fat diet (HFD), C57BL/6N mice received fecal microbiota for 8weeks from donor mice by oral gavage, continuing HFD feeding. Stool samples came from mice that were treated with TEL (8mg/kg/d by gavage, 12weeks), thus remaining lean despite HFD feeding (BL/6>fTEL), while controls received feces samples from vehicle/HFD-treated obese mice (BL/6>fVEH). Microbiota of the stool samples from these acceptor mice was analyzed by 16S rRNA gene amplicon sequencing. Weight gain was lower in BL6>fTEL than in BL6>fVEH mice after 3 but not 8weeks. Energy homeostasis, insulin sensitivity, and body composition did not differ between the two groups. β-diversity indicated group differences (F = 2.27, p = 0.005). Although the Firmicutes/Bacteroides ratio did not differ, abundances of distinct phyla, families, and genera varied. Among others, Ruminococcaceae and Desulfovibrionaceae, Desulfovibrionia uncl., and Lachnospiraceae uncl. were lower in BL/6>fTEL than in BL/6>fVEH mice. Moreover, the correlation between body weight and Lachnospiraceae, Desulfovibrionaceae, Desulfovibrionia uncl., or Desulfovibrio was positive in BL/6>fVEH and negative in BL/6>fTEL mice. As FMT from TEL-pretreated mice influences the microbiota in acceptor mice with slight weight-reducing effects, we confirm the relevance of TEL-related microbiota changes for weight reduction, most likely independent of the transferred stool-residual TEL effect on the host metabolism.

Attenuation of high-fat diet-induced weight gain by apolipoprotein A4.

Apolipoprotein A4 (APOA4) is synthesized by the small intestine in response to dietary lipids. Chronic exposure to a high-fat diet (HFD) desensitizes lipid-induced APOA4 production and attenuates brown adipose tissue (BAT) thermogenesis. We hypothesized that exogenous APOA4 could increase BAT thermogenesis and energy expenditure in HFD-fed mice, resulting in decreased obesity and improved glucose tolerance. BAT and inguinal white adipose tissue (IWAT) thermogenesis, body composition, energy intake and expenditure, and locomotor activity were measured using an infrared camera, immunoblots, quantitative magnetic resonance imaging, and a comprehensive lab animal monitoring system. An intraperitoneal glucose tolerance test and hepatic lipid accumulation and steatosis were assayed. Mice receiving continuous infusion of APOA4 for the last 4 weeks of 10 weeks of HFD feeding gained no additional body weight and had reduced fat mass but enhanced BAT and IWAT thermogenesis and energy expenditure, despite unaltered food intake and locomotor activity. Additionally, APOA4 infusion elevated fatty acid β oxidation; decreased lipogenesis, lipid accumulation, and steatosis in liver; and improved glucose tolerance. Maintenance of plasma APOA4 via exogenous APOA4 protein parallels elevation of BAT and IWAT thermogenesis, hepatic fatty acid β oxidation, and overall energy expenditure, with subsequent prevention of additional weight gain in HFD-fed obese mice.

Divergent roles of RIPK3 and MLKL in high-fat diet-induced obesity and MAFLD in mice.

Cell death frequently occurs in the pathogenesis of obesity and metabolic dysfunction-associated fatty liver disease (MAFLD). However, the exact contribution of core cell death machinery to disease manifestations remains ill-defined. Here, we show via the direct comparison of mice genetically deficient in the essential necroptotic regulators, receptor-interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like (MLKL), as well as mice lacking apoptotic caspase-8 in myeloid cells combined with RIPK3 loss, that RIPK3/caspase-8 signaling regulates macrophage inflammatory responses and drives adipose tissue inflammation and MAFLD upon high-fat diet feeding. In contrast, MLKL, divergent to RIPK3, contributes to both obesity and MAFLD in a manner largely independent of inflammation. We also uncover that MLKL regulates the expression of molecules involved in lipid uptake, transport, and metabolism, and congruent with this, we discover a shift in the hepatic lipidome upon MLKL deletion. Collectively, these findings highlight MLKL as an attractive therapeutic target to combat the growing obesity pandemic and metabolic disease.

Abstract 4114308: Defective in LYPLA1-Mediated Lysophosphatidylcholine Metabolism Contributes to Diabetes-Induced Atherosclerosis and Subsequent Myocardial Dysfunction

Background and Objective: Diabetes mellitus (DM) is a chronic metabolic condition that can cause serious damage to blood vessels and the heart. While current metabolomics research mainly focused on metabolic profiles during disease onset or at advanced stages, there remains a gap in understanding the molecular mechanisms of metabolites in the progression of diabetic cardiovascular disease. This study aims to explore effective strategies for preventing cardiovascular complications in diabetics by excavating metabolic pathways and mechanisms. Methods: Peripheral blood samples were obtained from 21 healthy individuals, 20 patients diagnosed with DM, 20 patients with coronary heart disease (CHD), and 25 patients with both DM and CHD (DC). Cardiac function, biochemical parameters and serum metabolome were detected. A specialized methodology with rigorous screening criteria was employed to identify differential metabolites associated with diabetes-induced CHD and cardiomyopathy. Mice were injected with LPC16:0 to assess cardiovascular function. Models of diabetes and diabetic atherosclerosis were induced by STZ injection and high-fat diet feeding in WT and ApoE -/- mice. Cardiac function and differential metabolites in aortic and cardiac tissues were assessed. The effect and molecular mechanism of LYPLA1 on vascular function, mitochondrial function, and metabolites-related enzymes were examined in human aortic endothelial cells (HAECs) and AC16 cardiomyocytes. Results: Cardiac function was markedly declined in DM and DC patients, as well as in mice with diabetes and diabetic atherosclerosis. However, CHD patients and atherosclerosis alone did not exhibit evident cardiac dysfunction. Key metabolites associated with diabetic cardiomyopathy and diabetes-induced CHD were identified as LPE18:1 and LPC16:0, respectively. Intraperitoneal administration of LPC16:0 in mice led to decreased LYPLA1, severe myocardial anomalies, and the appearance of plaques in the aortic arch. Either LYPLA1 knockdown or the treatment with high glucose and palmitic acid in HAECs resulted in impaired mitochondrial function, reduced intracellular NO and eNOS activity, which were mitigated by LYPLA1 overexpression. Conclusion: The metabolite LPC16:0 and the regulatory enzyme LYPLA1 are pivotal in driving the advancement of cardiovascular complications triggered by diabetes. Targeting LYPLA1 could represent a promising strategy for preventing diabetes-induced CHD and subsequent cardiomyopathy.

Improving diabetic wound healing: The therapeutic potential of allulose supplement in diabetic skin tissue repair and inflammation modulation

The increasing prevalence of type 2 diabetes mellitus (T2DM) worldwide presents significant challenges in the management of impaired tissue repair in diabetic skin wounds, which has emerged as a critical health concern. Addressing this issue while minimizing adverse effects remains crucial. Allulose has been shown to exhibit hypolipidemic and anti-inflammatory properties, alleviating obesity and atherosclerosis by improving insulin resistance and impaired glucose tolerance. However, its underlying effects and mechanisms in repairing diabetic skin damage remain poorly understood. In this study, we demonstrated that oral administration of allulose remarkably ameliorated T2DM-compromised skin tissue wound associated with the stimulation of skin granulation, surrounding tissue formation, and activated fibroblasts, under high-fat diet (HFD) feeding condition. In addition, administration partially promoted collagen deposition, reduced M1 macrophage polarization, facilitated neovascularization, and mitigated tissue inflammation in the T2DM rats upon HFD feeding. Moreover, allulose could significantly alleviate high glucose stress condition-induced inflammatory response, correlative with modulation of p38/NLRP3/Caspase-1 signaling. In addition, allulose could also ameliorate high glucose stress-compromised cell viability and proliferative capacity, related to stimulation of mTOR pathway in part. Taken together, our study revealed that T2DM compromised some certain factors which are crucial for skin tissue healing and wound repair upon HFD condition. The work highlighted the potential beneficial effects of orally administered allulose for healing diabetic skin wounds and supported a novel strategy for managing diabetes patients adjunctively with allulose dietary supplement.

Comparative Transcriptome Analysis Reveals the Impact of a High-Fat Diet on Hepatic Metabolic Function in Tilapia (Oreochromis niloticus).

Hepatic steatosis is prevalent among cultured fish, yet the molecular mechanisms remain incompletely understood. This study aimed to assess changes in hepatic metabolic function in tilapia and to explore the underlying molecular mechanisms through transcriptomic analyses. Tilapia were allocated into two groups: a normal control (Ctr)-fed group and a high-fat diet (HFD)-fed group. Serum biochemical analyses revealed that HFD feeding led to liver damage and lipid accumulation, characterized by elevated levels of glutamic-pyruvic transaminase (GPT), glutamic-oxaloacetic transaminase (GOT), triglycerides (TGs), and total cholesterol (TC). Transcriptome analysis showed that 538 genes were significantly downregulated, and 460 genes were significantly upregulated in the HFD-fed fish. Gene Ontology (GO) enrichment analysis showed that these differentially expressed genes (DEGs) were apparently involved in the lipid metabolic process and monocarboxylic acid metabolic process. Meanwhile, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated significant alterations in pathways of steroid biosynthesis, porphyrin metabolism, terpenoid backbone biosynthesis, and retinol metabolism after HFD feeding. Additionally, results from Gene Set Enrichment Analysis (GSEA) revealed that gene expression patterns in pathways including oxidative phosphorylation, protein export, protein processing in the endoplasmic reticulum, and ribosome biogenesis were positively enriched in the HFD-fed tilapia. These findings provide novel insights into the mechanisms underlying HFD-induced hepatic dysfunction in fish, contributing to the optimization of feeding strategies in aquaculture.

Hepatic vagal afferents convey clock-dependent signals to regulate circadian food intake.

Circadian desynchrony induced by shiftwork or jet lag is detrimental to metabolic health, but how synchronous or desynchronous signals are transmitted among tissues is unknown. We report that liver molecular clock dysfunction is signaled to the brain through the hepatic vagal afferent nerve (HVAN), leading to altered food intake patterns that are corrected by ablation of the HVAN. Hepatic branch vagotomy also prevents food intake disruptions induced by high-fat diet feeding and reduces body weight gain. Our findings reveal a homeostatic feedback signal that relies on communication between the liver and the brain to control circadian food intake patterns. This identifies the hepatic vagus nerve as a potential therapeutic target for obesity in the setting of chronodisruption.

Chemogenetic activation of hepatic G12 signaling ameliorates hepatic steatosis and obesity

ObjectiveHepatic steatosis, the early stage of nonalcoholic fatty liver disease (NAFLD), currently lacks targeted pharmacological treatments. G protein-coupled receptors (GPCRs) in hepatocytes differentially regulate lipid metabolism depending on their coupling profile of G protein subtypes. Unlike Gs, Gi, and Gq signaling, the role of G12 signaling in hepatic steatosis remains elusive. The objective of this study was to investigate the effect of G12 signaling on hepatic steatosis and obesity and its mechanisms. MethodsWe generated mice expressing a G12-coupled designer GPCR in a liver-specific manner. We performed phenotypic analysis in the mice under the condition of fasting (acute hepatic steatosis model) or high-fat diet feeding (chronic hepatic steatosis model). ResultsIn acute and chronic hepatic steatosis models, chemogenetic activation of hepatic G12 signaling suppressed the progression of hepatic steatosis. The treatment led to an increased triglyceride secretion with little effect on mitochondrial respiratory activity, fatty acid oxidation, de novo lipogenesis, and fatty acid uptake. Furthermore, in a high-fat-diet-induced obesity model, activation of the G12-coupled designer GPCR exerted anti-obesity effects with increased whole-body energy expenditure and fat oxidation. Anti-FGF21 antibody treatment showed that the anti-obesity effects of the hepatic G12D activation relied in part on the hepatokine FGF21. ConclusionsOur findings indicate that the activation of G12 signaling in the liver has the potential to prevent hepatic steatosis and obesity. This discovery provides a strong rationale for the development of drugs targeting G12-coupled GPCRs expressed in the liver.

Loss of NOX4 results in a sexually dimorphic response to high fat diet feeding in liver, bone and muscle

Loss of NOX4 results in a sexually dimorphic response to high fat diet feeding in liver, bone and muscle

The mitochondrial enzyme pyruvate carboxylase restricts pancreatic β-cell senescence by blocking p53 activation.

Defective glucose-stimulated insulin secretion (GSIS) and β-cell senescence are hallmarks in diabetes. The mitochondrial enzyme pyruvate carboxylase (PC) has been shown to promote GSIS and β-cell proliferation in the clonal β-cell lines, yet its physiological relevance remains unknown. Here, we provide animal and human data showing a role of PC in protecting β-cells against senescence and maintaining GSIS under different physiological and pathological conditions. β-cell-specific deletion of PC impaired GSIS and induced β-cell senescence in the mouse models under either a standard chow diet or prolonged high-fat diet feeding. Transcriptomic analysis indicated that p53-related senescence and cell cycle arrest are activated in PC-deficient islets. Overexpression of PC inhibited hyperglycemia- and aging-induced p53-related senescence in human and mouse islets as well as INS-1E β-cells, whereas knockdown of PC provoked senescence. Mechanistically, PC interacted with MDM2 to prevent its degradation via the MDM2 binding motif, which in turn restricts the p53-dependent senescent program in β-cells. On the contrary, the regulatory effects of PC on GSIS and the tricarboxylic acid (TCA) anaplerotic flux are p53-independent. We illuminate a function of PC in controlling β-cell senescence through the MDM2-p53 axis.