High-fat Diet Feeding Research Articles

Bletilla striata polysaccharides alleviate metabolic dysfunction-associated steatotic liver disease through enhancing hepatocyte RelA/ HNF1α signaling

BACKGROUND Bletilla striata polysaccharides (BSP) have antioxidant, immune regulation, and anti-fibrotic activities. However, the therapeutic effect and mechanisms underlying the action of BSP in metabolic dysfunction-associated steatotic liver disease (MASLD) have not been fully understood. AIM To investigate the therapeutic effects and mechanisms of BSP on MASLD by centering on the hepatocyte nuclear factor kappa B p65 (RelA)/hepatocyte nuclear factor-1 alpha (HNF1α) signaling. METHODS A mouse model of MASLD was induced by feeding with a high-fat-diet (HFD) and a hepatocyte model of steatosis was induced by treatment with sodium oleate (SO) and sodium palmitate (SP). The therapeutic effects of BSP on MASLD were examined in vivo and in vitro . The mechanisms underlying the action of BSP were analyzed for their effect on lipid metabolism disorder, endoplasmic reticulum (ER) stress, and the RelA/HNF1α signaling. RESULTS HFD feeding reduced hepatocyte RelA and HNF1α expression, induced ER stress, lipid metabolism disorder, and necroptosis in mice, which were significantly mitigated by treatment with BSP. Furthermore, treatment with BSP or BSP-containing conditional rat serum significantly attenuated the sodium oleate/sodium palmitate (SO/SP)-induced hepatocyte steatosis by decreasing lipid accumulation, and lipid peroxidation, and enhancing the expression of RelA, and HNF1α. The therapeutic effects of BSP on MASLD were partially abrogated by RELA silencing in mice and RELA knockout in hepatocytes. RELA silencing or knockout significantly down-regulated HNF1α expression, and remodeled ER stress and oxidative stress responses during hepatic steatosis. CONCLUSION Treatment with BSP ameliorates MASLD, associated with enhancing the RelA/HNF1α signaling, remodeling ER stress and oxidative stress responses in hepatocytes.

NLRP6 overexpression improves nonalcoholic fatty liver disease by promoting lipid oxidation and decomposition in hepatocytes through the AMPK/CPT1A/PGC1A pathway.

To investigate the regulatory role of nucleotide-bound oligomerized domain-like receptor containing pyrin-domain protein 6 (NLRP6) in liver lipid metabolism and non-alcoholic fatty liver disease (NAFLD). Mouse models with high-fat diet (HFD) feeding for 16 weeks (n=6) or with methionine choline-deficient diet (MCD) feeding for 8 weeks (n=6) were examined for the development of NAFLD using HE and oil red O staining, and hepatic expressions of NLRP6 were detected with RT-qPCR, Western blotting, and immunohistochemical staining. Cultured human hepatocytes (LO2 cells) with adenovirus-mediated NLRP6 overexpression or knock-down were treated with palmitic acid (PA) in the presence or absence of compound C (an AMPK inhibitor), and the changes in cellular lipid metabolism were examined by measuring triglyceride, ATP and β-hydroxybutyrate levels and using oil red staining, RT-qPCR, and Western blotting. HFD and MCD feeding both resulted in the development of NAFLD in mice, which showed significantly decreased NLRP6 expression in the liver. In PA-treated LO2 cells, NLRP6 overexpression significantly decreased cellular TG content and lipid deposition, while NLRP6 knockdown caused the opposite effects. NLRP6 overexpression in PA-treated LO2 cells also increased mRNA and protein expressions of PGC1A and CPT1A, levels of ATP and β-hydroxybutyrate, and the phosphorylation level of AMPK pathway; the oxidative decomposition of lipids induced by Ad-NLRP6 was inhibited by the use of AMPK inhibitors. NLRP6 overexpression promotes lipid oxidation and decomposition through AMPK/CPT1A/PGC1A to alleviate lipid deposition in hepatocytes.

Effect of cardiomyocyte-specific lipid phosphate phosphatase 3 overexpression on high-fat diet-induced cardiometabolic dysfunction in mice.

Lipid phosphate phosphatase 3 (LPP3) is a membrane-bound enzyme that hydrolyzes lipid phosphates including the bioactive lipid, lysophosphatidic acid (LPA). Elevated circulating LPA production and cellular LPA signaling are implicated in obesity-induced metabolic and cardiac dysfunction. Deletion of LPP3 in the cardiomyocyte increases circulating LPA levels and causes heart failure and mitochondrial dysfunction in mice. To examine the influence of LPP3 modulation in the cardiomyocyte on obesity-induced cardiomyopathy, we generated mice with cardiomyocyte-specific LPP3 overexpression (LPP3OE mice) driven by the α myosin heavy chain promoter. Female and male control (LPP3FL) and LPP3OE mice were fed low-fat diet (LFD) or high-fat diet (HFD) for up to 22-23 weeks, followed by the analysis of glucose homeostasis, cardiac function, plasma LPA levels, and mitochondrial respiration in cardiac myofibers. On LFD, both female and male LPP3OE mice had markedly reduced plasma LPA levels and increased pyruvate-linked respiration when compared to LPP3FL mice while body weight and global insulin sensitivity were similar between genotypes. Following HFD feeding, female LPP3OE mice were protected from an increase in plasma LPA levels, excess adiposity, systemic insulin resistance, and systolic and diastolic cardiac dysfunction compared to LPP3FL mice. Female LPP3OE mice also maintained elevated cardiac pyruvate-linked mitochondrial respiration following HFD feeding while mitochondrial respiration was similar between genotypes in HFD-fed male mice. This study suggests that cardiomyocyte-specific LPP3 upregulation protects particularly female mice from HFD-induced metabolic dysfunction and cardiomyopathy.

Obesity reshapes regulatory T cells in the visceral adipose tissue by disrupting cellular cholesterol homeostasis.

Regulatory T cells (Tregs) accumulate in the visceral adipose tissue (VAT) to maintain systemic metabolic homeostasis but decline during obesity. Here, we explored the metabolic pathways controlling the homeostasis, composition, and function of VAT Tregs under normal and high-fat diet feeding conditions. We found that cholesterol metabolism was specifically up-regulated in ST2hi VAT Treg subsets. Treg-specific deletion of Srebf2, the master regulator of cholesterol homeostasis, selectively reduced ST2hi VAT Tregs, increasing VAT inflammation and insulin resistance. Single-cell RNA/T cell receptor (TCR) sequencing revealed a specific loss and reduced clonal expansion of ST2hi VAT Treg subsets after Srebf2 deletion. Srebf2-mediated cholesterol homeostasis potentiated strong TCR signaling, which preferentially promoted ST2hi VAT Treg accumulation. However, long-term high-fat diet feeding disrupted VAT Treg cholesterol homeostasis and impaired clonal expansion of the ST2hi subset. Restoring Treg cholesterol homeostasis rescued VAT Treg accumulation in obese mice, suggesting that modulation of cholesterol homeostasis could be a promising strategy for Treg-targeted therapies in obesity-associated metabolic diseases.

Feruloylacetone and Its Analog Demethoxyferuloylacetone Mitigate Obesity-Related Muscle Atrophy and Insulin Resistance in Mice.

Obesity-induced muscle alterations, such as inflammation, metabolic dysregulation, and myosteatosis, lead to a decline in muscle mass and function, often resulting in sarcopenic obesity. Currently, there are no definitive treatments for sarcopenic obesity beyond lifestyle changes and dietary supplementation. Feruloylacetone (FER), a thermal degradation product of curcumin, and its analog demethoxyferuloylacetone (DFER), derived from the thermal degradation of bisdemethoxycurcumin, have shown potential antiobesity effects in previous studies. This study investigates the impact of FER and DFER on obesity-related glucose intolerance and muscle atrophy. High-fat diet (HFD) feeding resulted in muscle mass reduction and increased intramuscular triglyceride accumulation, both of which were mitigated by FER and DFER supplementation. The supplements activated the PI3K/Akt/mTOR signaling pathway, enhanced muscle protein synthesis, and decreased markers of muscle protein degradation. Additionally, FER and DFER supplementation improved glucose homeostasis in HFD-fed mice. The supplements also promoted the formation of a gut microbial consortium comprising Blautia intestinalis, Dubosiella newyorkensis, Faecalicatena fissicatena, Waltera intestinalis, Clostridium viride, and Caproiciproducens galactitolivorans, which contributed to the reduction of obesity-induced chronic inflammation. These findings suggest, for the first time, that FER and DFER may prevent obesity-related complications, including muscle atrophy and insulin resistance, thereby warranting further research into their long-term efficacy and safety.

Effects of tryptophan-selective lipidated GLP-1 peptides on the GLP-1 receptor.

Glucagon-like peptide 1 (GLP-1) receptor agonists (GLP-1 RAs) are widely used as antidiabetic and anti-obesity agents. Although conventional GLP-1 RAs such as liraglutide and semaglutide are acylated with fatty acids to delay their degradation by dipeptidylpeptidase-4 (DPP-4), the manufacturing process is challenging. We previously developed selectively lipidated GLP-1 peptides at their only tryptophan residue (peptide A having one 8-amino-3,6-dioxaoctanoic acid (miniPEG) linker and peptide B having three miniPEG linkers). In this study, we evaluated their effects on the GLP-1 receptor in vitro and in vivo. Both novel peptides were shown to increase cyclic adenosine monophosphate (cAMP) production and insulin secretion similarly to that by GLP-1(7-37) and liraglutide in vitro. In addition, these novel peptides lowered blood glucose levels by increasing insulin levels after oral administration of glucose and they suppressed gastrointestinal motility as effectively as liraglutide. The effects of peptide A on activation of satiety-promoting neurons in the arcuate nucleus and the consequent suppression of food intake and body weight were also similar to those of liraglutide, while the effects of peptide B were less than those of liraglutide. Under high-fat diet feeding, both long-term administration of peptide A and peptide B improved glucose tolerance and insulin sensitivity similarly to liraglutide. Thus, tryptophan-selective lipidated GLP-1 peptides are as effective as conventional GLP-1 RAs in reducing plasma glucose levels and body weight and may represent a less demanding method of manufacture of GLP-1 RAs.

B. vulgatus ameliorates high-fat diet-induced obesity through modulating intestinal serotonin synthesis and lipid absorption in mice

ABSTRACT The consumption of high-fat diets (HFD) and an imbalance in gut microbiome are linked to obesity. However, the intricate connection between them and the underlying mechanisms involved in lipid digestion and absorption remain largely unclear. This study shows that after 12 weeks of HFD feeding, C57BL/6J mice exhibit two distinct metabolic phenotypes with significant differences in gut microbiota composition. The LOW and LOW FMT group mice with increased Bacteroides are protected from obesity, insulin resistance, and lipid accumulation. Supplementation with B. vulgatus or cholic acid (CA) alleviates HFD-induced obesity and metabolic dysfunction. This is due to the accumulation of lipid droplets and the retention of chyle particles in jejunal epithelial cells, which reduces chyle intake in the jejunal mesentery after HFD. Decreased 5-HT synthesis in the jejunal enterochromaffin cells of these mice, along with reduced chyle intake in the jejunal mesentery after HFD in Tph1 △IEC, suggests that intestinal 5-HT is required for host lipid absorption. TRPV1, a calcium-permeable ion channel, mediates the basolateral 5-HT-induced increase of Isc and ion channel open probability. This study uncovers a novel signaling axis of microbiota-metabolite-5-HT and intracellular calcium-dependent lipid absorption, which may serve as the potential therapeutic targets for treating HFD-induced obesity.

Medial hypothalamic MC3R signalling regulates energy rheostasis in adult mice.

Although mammals resist both acute weight loss and weight gain, the neural circuitry mediating bi-directional defense against weight change is incompletely understood. Global constitutive deletion of the melanocortin-3-receptor (MC3R) impairs the behavioural response to both anorexic and orexigenic stimuli, with MC3R knockout mice demonstrating increased weight gain following anabolic challenges and increased weight loss following anorexic challenges (i.e. impaired energy rheostasis). However, the brain regions mediating this phenotype are not well understood. Here, we utilized MC3R floxed mice and viral injections of Cre-recombinase to selectively delete MC3R from the medial hypothalamus (MH) in adult mice. Behavioural assays were performed on these animals to test the role of MC3R in MH in the acute response to orexigenic and anorexic challenges. Complementary chemogenetic approaches were used in MC3R-Cre mice to localize and characterize the specific medial hypothalamic brain regions mediating the role of MC3R in energy homeostasis. Finally, we performed RNAscope in situ hybridization to map changes in the mRNA expression of MC3R, pro-opiomelanocortin and agouti-related peptide following energy rheostatic challenges, as well as to characterize the MC3R expressing cells in dorsal MH. Our results demonstrate that MC3R deletion in MH increases feeding and weight gain following high-fat diet feeding, and enhances the anorexic effects of semaglutide, in a sexually dimorphic manner. Furthermore, although the arcuate nucleus exerts an important role in MC3R-mediated effects on energy homeostasis, viral deletion in the dorsal MH also resulted in altered energy rheostasis, indicating that brain regions outside of the arcuate nucleus also contribute to the role of MC3R in energy rheostasis. Together, these results demonstrate that MC3R-mediated effects on energy rheostasis result from the loss of MC3R signalling in medial hypothalamic neurons and suggest an important role for dorsal-MH MC3R signalling in energy rheostasis. KEY POINTS: Melanocortin-3-receptor (MC3R) signalling regulates energy rheostasis in adult mice. Medial hypothalamus regulates energy rheostasis in adult mice. Energy rheostatic stimuli alter mRNA levels of agouti-related peptide, pro-opiomelanocortin and MC3R. Dorsal-medial hypothalamus (DMH) MC3R neurons increase locomotion and energy expenditure. MC3R cell types in DMH are sexually dimorphic.

Microglial activation and hypothalamic structural plasticity in HFD obesity: insights from semaglutide and minocycline.

High-fat diet (HFD)-induced microglial activation contributes to hypothalamic inflammation and obesity, but the mechanisms linking microglia to structural changes remain unclear. This study explored the role of microglia in impairing hypothalamic synaptic plasticity in diet-induced obesity mice and evaluated the therapeutic potential of semaglutide (Sema) and minocycline (MI). Six-week-old C57BL/6J mice were divided into low-fat diet and HFD groups. At week 30, the HFD-fed mice were treated daily with Sema or MI for six weeks. Confocal microscopy assessed hypothalamic dendritic spines, synaptic organization, and microglia-synapse interactions. We also analyzed microglial morphology, CD68/CD11b colocalization with Iba-1, synaptic marker expression, and phagocytosis-related pathways (C1q, C3, CD11b). BV2 microglia were used to examine the direct effects of Sema or MI on microglia and validate the invivo findings. HFD feeding induced microglial activation, as indicated by increased colocalization of CD68 or synaptophysin and CD11b with Iba-1, along with elevated C1q, C3, and CD11b expression, signaling enhanced synaptic phagocytosis. This was accompanied by reduced hypothalamic dendritic spines, decreased synaptic marker expression, and disrupted excitatory/inhibitory synaptic organization in the melanocortin system, as well as impaired glucose metabolism, disrupted leptin-ghrelin balance, and increased food intake and body weight. Sema and MI treatments reversed the pathological changes of microglial activation and restored hypothalamic synaptic structure, although their effects on synaptic organization and metabolic outcomes differed. Our findings highlight the key role of microglial activation in hypothalamic synaptic impairment in diet-induced obesity models, with Sema and MI possibly offering distinct therapeutic pathways to mitigate these impairments.

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.

Essential role of Card11 in airway hyperresponsiveness in high-fat diet-induced obese mice

A high-fat diet (HFD) can induce airway hyperresponsiveness (AHR) in obese mice, independent of allergic sensitization. This study aimed to identify the key molecules related to AHR in HFD-induced obese mice. In a cluster analysis of time series gene expression in the adipose and lung tissues of HFD-induced obese mice, we identified the Caspase Recruitment Domain Family Member 11 (Card11) gene as an essential molecule. We measured CARD11 expression in peripheral blood mononuclear cells (PBMCs) from obese individuals with asthma and performed Card11 signal inhibition in HFD-induced obese mice via Card11 siRNA. Card11 expression was significantly increased in M1 macrophages (IL-1β+CD11c+CD206- in CD11b+) in adipose tissue and in ILC3s (RORγt+ in IL7R+ of Lin-) in lung tissue from HFD-induced obese mice. In addition, CARD11+ populations among ILC3s and LPS-stimulated IL-1β+CD16+ monocytes from the PBMCs of obese individuals with asthma were significantly greater than those from obese controls or nonobese individuals with asthma. AHR in HFD-induced obese mice disappeared when we inhibited the Card11 signaling pathway by administering Card11 siRNA during the first or last seven weeks of the 13-week HFD feeding. Finally, we confirmed that Card11 siRNA decreased the number of M1 macrophages in adipose tissue and the number of ILC3s in lung tissue in vitro. Card11 significantly contributes to the development of AHR in HFD-induced obese mice by affecting immune cells in both adipose and lung tissues. The middle stage of HFD feeding seemed to be critical for these processes.

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.

Nesfatin-1 is involved in hyperbaric oxygen-mediated therapeutic effects in high fat diet-induced hyperphagia in mice.

Obesity is a worldwide health issue. Effective and safe methods for obesity management are highly desirable. In the current study, hyperbaric oxygen (HBO) treatment was investigated as a potential treatment against obesity-associated hyperphagia and hyperenergy intake. Diet induced obesity (DIO) mice model was established with high fat diet (HFD) feeding, HBO was then co-administered. Food and energy intake were assessed with nocturnal food intake assay. Immunohistochemistry for c-Fos was performed for neuronal activation in arcuate nucleus (ARC), paraventricular nucleus of hypothalamus (PVN) and lateral parabrachial nucleus (LPBN) of brain. Additionally, enzyme-linked immunosorbent assay (ELISA) in serum and immunofluorescence in LPBN were performed. Results indicated that HBO co-treatment effectively decreased food and energy intake in DIO mice, reverted the abnormal neuronal activation in the ARC and PVN, and enhanced both peripheral and central nesfatin-1 peptide levels without affecting serum leptin levels. While SHU9119 microinjection in LPBN effectively abolished the beneficial effects of HBO on body weight, visceral fat, nocturnal feeding and energy intake in DIO mice. In conclusion, HBO treatment could effectively protect against HFD-induced increase of food and energy intake, which is associated with its central effects against abnormal neuronal activation in ARC and PVN and enhanced peptide levels of nesfatin-1 both centrally and peripherally. The melanocortin system downstream of nesfatin-1 may exert a potential effect in this process.

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.

Modeling and Evaluation of Murine Diabetic Cardiomyopathy Model.

The underlying pathophysiological mechanisms of diabetic cardiomyopathy (DbCM), a leading cause of mortality among patients with type 2 diabetes mellitus (T2DM), remain poorly understood. The myocardial toxicity associated with T2DM is attributed to factors such as lipotoxicity, glucotoxicity, oxidative stress, reduced cardiac efficiency, and lipoapoptosis. Compared to rats, mice offer greater accessibility, cost-effectiveness, and broader applicability for animal experiments. Insulin resistance and impaired insulin secretion are crucial factors in the pathophysiology of T2DM. We introduce a novel nongenetic murine model that replicates the progression of human DbCM induced by a combination of high-fat diet (HFD) feeding and streptozotocin (STZ) injection. In this study, we used wild-type C57BL/6J mice, administering an HFD regimen for 12 weeks, followed by intraperitoneal injections of STZ for an additional 12 weeks to induce characteristic manifestations of T2DM. We conducted oral glucose tolerance tests and measured serum insulin concentrations to confirm the development of insulin resistance and insufficient insulin secretion. Cardiac structure and function were rigorously assessed through noninvasive transthoracic echocardiography. Pathological characteristics were evaluated through Masson's trichrome staining and wheat germ agglutinin (WGA) staining, revealing pathological features related to DbCM. Therefore, we provide a robust and versatile method for establishing a nongenetic murine model of DbCM.

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.