Enteric lactoferrin attenuates the development of high-fat and high-cholesterol diet-induced hypercholesterolemia and atherosclerosis in Microminipigs

Previously, we found that enteric lactoferrin (eLF) could reduce the visceral fat accumulation known to associate strongly with metabolic syndrome symptoms and consequently with an increased risk of atherosclerosis. In this study, the atherosclerosis-preventive potential of LF was assessed in a high-fat and high-cholesterol diet (HFCD)-induced hypercholesterolemia and atherosclerosis model using Microminipig?. Eight-week orally administered eLF remarkably reduced the HFCD-induced serum total and low-density lipoprotein cholesterol levels but not high-density lipoprotein cholesterol levels. A histological analysis of 15 arteries revealed that eLF systemically inhibited the development of atherosclerotic lesions. Pathway analysis using identified genes that characterized eLF administration in liver revealed significant changes in the steroid biosynthesis pathway (ssc00100) and all affected genes in this pathway were upregulated, suggesting that cholesterol synthesis inhibited by HFCD was recovered by eLF. In summary, eLF could potentially prevent the hypercholesterolemia and atherosclerosis through protecting homeostasis from HFCD-induced dysfunction of cholesterol metabolism.     

A high-fat diet and high-fat and high-cholesterol diet may affect glucose and lipid metabolism differentially through gut microbiota in mice

This study was conducted to investigate the effects of a high-fat diet (HFD) and high-fat and high-cholesterol diet (HFHCD) on glucose and lipid metabolism and on the intestinal microbiota of the host animal. A total of 30 four-week-old female C57BL/6 mice were randomly divided into three groups (n=10) and fed with a normal diet (ND), HFD, or HFHCD for 12 weeks, respectively. The HFD significantly increased body weight and visceral adipose accumulation and partly lowered oral glucose tolerance compared with the ND and HFHCD. The HFHCD increased liver weight, liver fat infiltration, liver triglycerides, and liver total cholesterol compared with the ND and HFD. Moreover, it increased serum high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and total cholesterol compared with the ND and HFD and upregulated alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase significantly. The HFHCD also significantly decreased the α-diversity of the fecal bacteria of the mice, to a greater extent than the HFD. The composition of fecal bacteria among the three groups was apparently different. Compared with the HFHCD-fed mice, the HFD-fed mice had more Oscillospira, Odoribacter, Bacteroides, and [Prevotella], but less [Ruminococcus] and Akkermansia. Cecal short-chain fatty acids were significantly decreased after the mice were fed the HFD or HFHCD for 12 weeks. Our findings indicate that an HFD and HFHCD can alter the glucose and lipid metabolism of the host animal differentially; modifications of intestinal microbiota and their metabolites may be an important underlying mechanism.     

高脂食物诱导的肥胖小鼠不同脑区即刻早期蛋白和酪氨酸羟化酶的变化

目的：在高脂食物诱导肥胖的小鼠中检测多巴胺神经元的表达。方法：10只雄性小鼠饲喂高脂膳食作为高脂食物组（HFD）,10只雄性小鼠饲喂10%脂肪膳食作为对照组（NCD）。实验第10周,小鼠禁食12 h后称重,尾静脉取血测定基础血糖水平;实验11周进行葡萄糖耐受（GTT）测试和胰岛素抵抗实验（ITT）;实验12周,动物禁食4 h后处死,测定血清胰岛素和瘦素（leptin）浓度,免疫组织化学法检测即刻早期蛋白（c-Fos-ir）和酪氨酸羟化酶（TH-ir）的表达。结果：饲喂12周高脂食物后,HFD组体重明显增加。GTT测试显示HFD组在15 min和30 min血糖浓度均明显高于NCD组（P<0.05）。ITT测试显示HFD组在15 min和30 min血糖浓度均显著高于NCD组（P<0.05）。同时,禁食后,HFD组的胰岛素浓度和leptin浓度显著高于NCD组（P<0.01）。免疫组化结果表明HFD组在伏隔核、下丘脑室旁核、腹侧背盖区和黑质的c-Fos-ir细胞数均明显多于NCD组（P<0.01）,且腹侧被盖区和黑质的TH-ir和共表达TH/Fos-ir细胞也显著多于NCD组（P<0.01）。而且HFD组VTA区和SN区TH-ir的细胞数与HFD组小鼠的终体重呈正相关（P<0.05）。结论：长期饲喂高脂食物导致的肥胖与奖赏系统多巴胺神经元的可塑性有关。     

CGI-58 knockdown in mice causes hepatic steatosis but prevents diet-induced obesity and glucose intolerance

Mutations of Comparative Gene Identification-58 (CGI-58) in humans cause triglyceride (TG) accumulation in multiple tissues. Mice genetically lacking CGI-58 die shortly after birth due to a skin barrier defect. To study the role of CGI-58 in integrated lipid and energy metabolism, we utilized antisense oligonucleotides (ASOs) to inhibit CGI-58 expression in adult mice. Treatment with two distinct CGI-58-targeting ASOs resulted in ∼80–95% knockdown of CGI-58 protein expression in both liver and white adipose tissue. In chow-fed mice, ASO-mediated depletion of CGI-58 did not alter weight gain, plasma TG, or plasma glucose, yet raised hepatic TG levels ∼4-fold. When challenged with a high-fat diet (HFD), CGI-58 ASO-treated mice were protected against diet-induced obesity, but their hepatic contents of TG, diacylglycerols, and ceramides were all elevated, and intriguingly, their hepatic phosphatidylglycerol content was increased by 10-fold. These hepatic lipid alterations were associated with significant decreases in hepatic TG hydrolase activity, hepatic lipoprotein-TG secretion, and plasma concentrations of ketones, nonesterified fatty acids, and insulin. Additionally, HFD-fed CGI-58 ASO-treated mice were more glucose tolerant and insulin sensitive. Collectively, this work demonstrates that CGI-58 plays a critical role in limiting hepatic steatosis and maintaining hepatic glycerophospholipid homeostasis and has unmasked an unexpected role for CGI-58 in promoting HFD-induced obesity and insulin resistance.     

CXCL14 enhances insulin-dependent glucose uptake in adipocytes and is related to high-fat diet-induced obesity

Accumulating evidence suggests an association between obesity and adipose tissue inflammation. Chemokines are involved in the regulation of inflammation status. Chemokine (C-X-C motif) ligand 14 (CXCL14) is known to be a chemoattractant for monocyte and dendritic cells. Recently, it was reported that CXCL14-deficient mice show resistance to high-fat diet-induced obesity. In this study, we identified CXCL14 as a growth hormone (GH)-induced gene in HepG2 hepatoma cells. Substantial in vivo expression of CXCL14 was detected in the adipose tissue and liver. Its expression and secretion were strikingly increased by insulin administration and high-fat diet. Intriguingly, incubation of 3T3-L1 adipocytes with CXCL14 stimulated insulin-dependent glucose uptake. Further, this effect was associated with enhanced insulin signaling. CXCL14 enhanced the insulin-induced tyrosine phosphorylation of insulin receptors and insulin receptor substrate-1. These results suggest that CXCL14 plays a causal role in high-fat diet-induced obesity.     

Transplantation of beige adipose organoids fabricated using adipose acellular matrix hydrogel improves metabolic dysfunction in high-fat diet-induced obesity and type 2 diabetes mice

Transplantation of brown adipose tissue (BAT) is a promising approach for treating obesity and metabolic disorders. However, obtaining sufficient amounts of functional BAT or brown adipocytes for transplantation remains a major challenge. In this study, we developed a hydrogel that combining adipose acellular matrix (AAM) and GelMA and HAMA that can be adjusted for stiffness by modulating the duration of light-crosslinking. We used human white adipose tissue-derived microvascular fragments to create beige adipose organoids (BAO) that were encapsulated in either a soft or stiff AAM hydrogel. We found that BAOs cultivated in AAM hydrogels with high stiffness demonstrated increased metabolic activity and upregulation of thermogenesis-related genes. When transplanted into obese and type 2 diabetes mice, the HFD + BAO group showed sustained improvements in metabolic rate, resulting in significant weight loss and decreased blood glucose levels. Furthermore, the mice showed a marked reduction in nonalcoholic liver steatosis, indicating improved liver function. In contrast, transplantation of 2D-cultured beige adipocytes failed to produce these beneficial effects. Our findings demonstrate the feasibility of fabricating beige adipose organoids in vitro and administering them by injection, which may represent a promising therapeutic approach for obesity and diabetes.     

Late‐life time‐restricted feeding and exercise differentially alter healthspan in obesity

Aging and obesity increase multimorbidity and disability risk, and determining interventions for reversing healthspan decline is a critical public health priority. Exercise and time‐restricted feeding (TRF) benefit multiple health parameters when initiated in early life, but their efficacy and safety when initiated at older ages are uncertain. Here, we tested the effects of exercise versus TRF in diet‐induced obese, aged mice from 20 to 24 months of age. We characterized healthspan across key domains: body composition, physical, metabolic, and cardiovascular function, activity of daily living (ADL) behavior, and pathology. We demonstrate that both exercise and TRF improved aspects of body composition. Exercise uniquely benefited physical function, and TRF uniquely benefited metabolism, ADL behavior, and circulating indicators of liver pathology. No adverse outcomes were observed in exercised mice, but in contrast, lean mass and cardiovascular maladaptations were observed following TRF. Through a composite index of benefits and risks, we conclude the net healthspan benefits afforded by exercise are more favorable than those of TRF. Extrapolating to obese older adults, exercise is a safe and effective option for healthspan improvement, but additional comprehensive studies are warranted before recommending TRF.     

耐力训练对ApoE-/-致AS小鼠IL-18和IL-10表达的影响

目的：深入观察耐力训练对载脂蛋白E基因敲除（ApoE^-/-）致动脉粥样硬化（AS）小鼠白介素18（IL-18）和白介素10（IL-10）的影响,探讨运动防治AS的可能机制。方法：选取8周龄雄性ApoE^-/-小鼠20只：随机分为2组（n=10）：AS模型组（AC组）和运动干预组（AE组）,AE组进行跑台耐力训练;选取8周龄C57BL/6J雄性小鼠10只作为正常对照组（CC组）。实验持续12周,取主动脉制作冰冻切片,分别用于观察主动脉AS斑块和病理变化以及主动脉IL-18、IL-10蛋白表达;采用ELISA法检测血清IL-18、IL-10水平。结果：①12周高脂膳食致ApoE^-/-小鼠发生典型的AS病变,耐力训练使AS斑块面积显著减少（P<0.01）,病变程度显著减轻。②与CC组比较,AC组、AE组小鼠血清IL-18和IL-10水平均显著升高（P<0.01）,且AC组IL-18/IL-10比值显著升高（P<0.01）。AE组血清IL-18水平及IL-18/IL-10比值均显著低于AC组（P<0.01）。③与CC组比较,AC组、AE组小鼠主动脉IL-10和IL-18蛋白表达均显著升高（P<0.01）,AE组IL-10表达显著高于AC组（P<0.05）,IL-18表达显著低于AC组（P<0.05）。结论：耐力训练通过降低血液和主动脉IL-18及提高IL-10水平,增强了主动脉血管抗炎能力,从而发挥抗AS的作用。     

Dietary alpha‐ketoglutarate promotes beige adipogenesis and prevents obesity in middle‐aged mice

Aging usually involves the progressive development of certain illnesses, including diabetes and obesity. Due to incapacity to form new white adipocytes, adipose expansion in aged mice primarily depends on adipocyte hypertrophy, which induces metabolic dysfunction. On the other hand, brown adipose tissue burns fatty acids, preventing ectopic lipid accumulation and metabolic diseases. However, the capacity of brown/beige adipogenesis declines inevitably during the aging process. Previously, we reported that DNA demethylation in the Prdm16 promoter is required for beige adipogenesis. DNA methylation is mediated by ten–eleven family proteins (TET) using alpha‐ketoglutarate (AKG) as a cofactor. Here, we demonstrated that the circulatory AKG concentration was reduced in middle‐aged mice (10‐month‐old) compared with young mice (2‐month‐old). Through AKG administration replenishing the AKG pool, aged mice were associated with the lower body weight gain and fat mass, and improved glucose tolerance after challenged with high‐fat diet (HFD). These metabolic changes are accompanied by increased expression of brown adipose genes and proteins in inguinal adipose tissue. Cold‐induced brown/beige adipogenesis was impeded in HFD mice, whereas AKG rescued the impairment of beige adipocyte functionality in middle‐aged mice. Besides, AKG administration up‐regulated Prdm16 expression, which was correlated with an increase of DNA demethylation in the Prdm16 promoter. In summary, AKG supplementation promotes beige adipogenesis and alleviates HFD‐induced obesity in middle‐aged mice, which is associated with enhanced DNA demethylation of the Prdm16 gene.     

Proteoglycan 4 deficiency protects against glucose intolerance and fatty liver disease in diet-induced obese mice

Objective

Proteoglycan 4 (Prg4) has emerged from human association studies as a possible factor contributing to weight gain, dyslipidemia and insulin resistance. In the current study, we investigated the causal role of Prg4 in controlling lipid and glucose metabolism in mice.