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Obesity accelerates age-related memory deficits and alters white matter tract integrity in Ldlr-/-.Leiden mice

ABSTRACT: - Background: Obesity in mid-adulthood has been suggested to promote brain aging and is associated with progressive cognitive impairment later in life. However, the structural and functional alterations that underlie obesity-related cognitive dysfunction are still poorly understood, partly owing to the lack of translational models replicating age- and obesity-related brain pathology. - Methods: The effect of age and high-fat diet (HFD)-induced obesity was investigated in adult Ldlr-/-.Leiden mice, an established translational model for obesity and its comorbidities. During mid-adulthood, from three to eight months of age, brain structure and function (hippocampal volume, cortical thickness, white matter integrity, cerebral blood flow (CBF), resting-state functional connectivity) were monitored with brain magnetic resonance imaging, and cognitive function was evaluated using cognitive tests. Brain pathology was further examined with histopathological and gene expression analyses. - Results: Ldlr-/-.Leiden mice showed age-related decreases in cortical thickness, CBF, brain connectivity, and neurogenesis along with the development of neuroinflammation and (short-term) memory impairments. On HFD feeding, Ldlr-/-.Leiden mice exhibited similar features, but memory deficits started at a younger age than in chow-fed mice. HFD-fed mice additionally showed a rise in CBF with concomitant decline in fractional anisotropy in white matter tracts. Analyses of hippocampal gene expression further revealed an age-related suppression of processes related to metabolic and neuronal function while HFD feeding strongly activated neuroinflammatory pathways. - Conclusions: Ldlr-/-.Leiden mice show similar critical age-related changes in brain structure and function as observed in humans. In this mouse model, HFD feeding particularly trigger disturbances in brain blood perfusion and white matter tract integrity, which may underlie an accelerated cognitive decline in obesity.

ORGANISM(S): Mus musculus

PROVIDER: GSE294054 | GEO | 2025/04/30

REPOSITORIES: GEO

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Project description:Abstract Obesity has been linked to vascular dysfunction, cognitive impairment and neurodegenerative diseases. However, experimental models that recapitulate brain pathology in relation to obesity and vascular dysfunction are still lacking. In this study we performed the histological and histochemical characterization of brains from Ldlr-/-.Leiden mice, an established model for obesity and associated vascular disease. 18 week-old and 50 week-old Ldlr-/-.Leiden male mice were compared with age-matched C57BL/6J mice. We then assessed the effect of high-fat diet (HFD)-induced obesity on brain pathology in Ldlr-/-.Leiden mice and tested whether a treatment with an anti-complement component 5 antibody, a terminal complement pathway inhibitor recently shown to reduce vascular disease, can attenuate neurodegeneration and neuroinflammation. Histological analyses were complemented with Next Generation Sequencing (NGS) analyses of the hippocampus to unravel molecular pathways underlying brain histopathology. We show that Ldlr-/-.Leiden mice have more severe neurodegeneration and show an age-dependent astrogliosis that is not observed in age-matched C57BL/6J controls. This was substantiated by pathway enrichment analysis using the NGS data which showed that oxidative phosphorylation, EIF2 signaling and mitochondrial dysfunction pathways, all associated with neurodegeneration, were significantly altered in the hippocampus of Ldlr-/-.Leiden mice compared with controls. Obesity-inducing HFD-feeding did not aggravate neurodegeneration and astrogliosis. However, brains from HFD-fed Ldlr-/-.Leiden mice showed reduced IBA-1 immunoreactivity and increased CD68 immunoreactivity compared with chow-fed controls, indicating an altered overall microglial immunophenotype by HFD feeding. The systemic administration of an anti-C5 treatment partially restored the HFD effect on microglial immunophenotype. In addition, NGS data of hippocampi from Ldlr-/-.Leiden mice showed that HFD affected multiple molecular pathways: HFD notably inactivated synaptogenesis and activated neuroinflammation pathways. The anti-C5 treatment restored the HFD-induced effect on molecular pathways to a large extent. This study shows that the Ldlr-/-.Leiden mouse model is suitable to study brain histopathology and associated biological processes in a context of obesity and provides evidence of the potential therapeutic value of anti-complement therapy against obesity-induced neuroinflammation.

Project description:Background: Non-alcoholic fatty liver disease (NAFLD) is a complex multifactorial disorder that is characterised by dysfunctional lipid metabolism and cholesterol homeostasis, and a related chronic inflammatory response. NAFLD has become the most common cause of chronic liver disease in many countries, and its prevalence continues to rise in parallel with increasing rates of obesity. Here, we evaluated the putative NAFLD-attenuating effects of a multicomponent medicine consisting of 24 ingredients: Hepar compositum (HC-24). Methods: Ldlr-/-.Leiden mice were fed a high-fat diet (HFD) with a macronutrient composition and cholesterol content comparable to human diets for 24 weeks to induce obesity-associated metabolic dysfunction, including hepatic steatosis and inflammation. HC-24 or vehicle control was administered intraperitoneally 3 times/week (1.5 ml/kg) for the last 18 weeks of the study. Histological analyses of liver and adipose tissue were combined with extensive hepatic transcriptomics analysis (next generation sequencing). Transcriptomics results were further substantiated with immunohistochemical and liver lipid analyses. Results: HFD feeding induced obesity and metabolic dysfunction that was associated with adipose tissue inflammation and increased gut permeability. In the liver, HFD-feeding resulted in a disturbance of cholesterol homeostasis and an associated inflammatory response. HC-24 did not affect body weight, metabolic risk factors, adipose tissue inflammation or gut permeability. While HC-24 did not affect total liver steatosis, there was a pronounced reduction in lobular inflammation in HC-24-treated animals, which was associated with modulation of genes involved in inflammation (e.g. neutrophil chemokine Cxcl1) and cholesterol homeostasis (i.e. predicted effect on 'cholesterol' as an upstream regulator, based on gene expression changes associated with cholesterol handling). These effects were confirmed by immunohistochemical staining of neutrophils and biochemical analysis of hepatic free cholesterol content. Intrahepatic free cholesterol levels were found to correlate significantly with the number of inflammatory aggregates in the liver, thereby providing a potential rationale for the observed anti-inflammatory effects of HC-24. Conclusions: Free cholesterol accumulates in the liver of Ldlr-/-.Leiden mice under physiologically translational dietary conditions, and this is associated with the development of hepatic inflammation. The multicomponent medicine HC-24 reduces accumulation of free cholesterol and has molecular and cellular anti-inflammatory effects in the liver.

Project description:- Background: Fibroblast growth factor 21 (FGF21) is considered a promising target for treatment of obesity-associated metabolic diseases including metabolic dysfunction-associated steatohepatitis (MASH) and atherosclerosis. Here, we evaluated the effects of a humanized bispecific anti-FGFR1/KLB agonist antibody (bFKB1) that specifically targets FGFR1c and β-klotho, in a translational preclinical model that develops MASH and atherosclerosis. - Methods: Ldlr-/-.Leiden mice were fed a high-fat diet (HFD) for 20 weeks, after which mice were treated with an isotype control antibody or bFKB1 for 12 weeks. Effects on pre-existent MASH and atherosclerosis were assessed histopathologically and biochemically. Underlying mechanisms of bFKB1 treatment were investigated by hepatic transcriptomics analysis (NGS). Results: bFKB1 lowered body weight and adipose tissue mass without reducing food intake. bFKB1 intervention reduced plasma insulin, cholesterol, triglycerides, ALT and liver weight. liver steatosis, inflammation and NAS score were significantly lowered. Histological measurement of fibrosis was not significantly affected by the treatment, but new collagen formation was significantly inhibited by bFKB1. Correspondingly, hepatic inflammatory and profibrotic transcriptional programs were broadly inactivated by the treatment. In epididymal white adipose tissue, bFKB1 intervention reduced adipocyte size and inflammation and induced browning, signified by increased UCP1 expression. In the vasculature, bFKB1 had anti-atherogenic effects, lowering total atherosclerotic lesion area, that could be attributed to a reduction In severe type V lesions. - Conclusion: The bispecific anti-FGFR1/KLB agonist antibody bFKB1 has strong beneficial metabolic effects in HFD-fed Ldlr-/-.Leiden mice that are associated with a reduction in liver steatosis, inflammation and atherosclerosis. Liver fibrosis was not affected, yet analysis of new collagen formation and profibrotic transcriptional programs indicate that bFKB1 treatment may have antifibrotic potential in a longer treatment duration, consistent with a recent clinical study using a FGF21 mimetic.

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Obesity accelerates age-related memory deficits and alters white matter tract integrity in Ldlr-/-.Leiden mice

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