Guangneng Liao

Serum metabolic variables associated with impaired glucose tolerance induced by high-fat-high-cholesterol diet in Macaca mulatta

Dyslipidemia caused by ‘Western-diet pattern’ is a strong risk factor for the onset of diabetes. This study aimed to disclose the relationship between the serum metabolite changes induced by habitual intake of high-fat and high-cholesterol (HFHC) diet and the development of impaired glucose tolerance (IGT) and insulin resistance through animal models of Macaca mulatta. Sixteen M. mulatta (six months old) were fed a control diet or a HFHC diet for 18 months. The diet effect on serum metabolic profiles was investigated by longitudinal research. Islet function was assessed by intravenous glucose tolerance and hyperinsulinemic-euglycemic clamp test. Metabonomics were determined by 1 H proton nuclear magnetic resonance spectroscopy. Prolonged diet-dependent hyperlipidemia facilitated visceral fat accumulation in liver and skeletal muscle and disorder of glucose homeostasis in juvenile monkeys. Glucose disappearance rate (KGlu) and insulin response to the glucose challenge effects in HFHC monkeys were significantly lower than in control monkeys. Otherwise, serum trimethylamine-N-oxide (TMAO), lactate and leucine/isoleucine were significantly higher in HFHC monkeys. Sphingomyelin and choline were the most positively correlated with KGlu (R2 = 0.778), as well as negative correlation (R2 = 0.64) with total cholesterol. The HFHC diet induced visceral fat, abnormal lipid metabolism and IGT prior to weight gain and body fat content increase in juvenile monkeys. We suggest that increased serum metabolites, such as TMAO, lactate, branched-chain amino acids and decreased sphingomyelin and choline, may serve as possible predictors for the evaluation of IGT and insulin resistance risks in the prediabetic state.

GLP-1 receptor agonist ameliorates obesity-induced chronic kidney injury via restoring renal metabolism homeostasis

Increasing evidence indicates that obesity is highly associated with chronic kidney disease (CKD). GLP-1 receptor (GLP-1R) agonist has shown benefits on kidney diseases, but its direct role on kidney metabolism in obesity is still not clear. This study aims to investigate the protection and metabolic modulation role of liraglutide (Lira) on kidney of obesity. Rats were induced obese by high-fat diet (HFD), and renal function and metabolism changes were evaluated by metabolomic, biological and histological methods. HFD rats exhibited systemic metabolic disorders such as obesity, hyperlipidemia and impaired glucose tolerance, as well as renal histological and function damages, while Lira significantly ameliorated these adverse effects in HFD rats. Metabolomic data showed that Lira directly reduced renal lipids including fatty acid residues, cholesterol, phospholipids and triglycerides, and improved mitochondria metabolites such as succinate, citrate, taurine, fumarate and nicotinamide adenine dinucleotide (NAD+) in the kidney of HFD rats. Furthermore, we revealed that Lira inhibited renal lipid accumulation by coordinating lipogenic and lipolytic signals, and partly rescued renal mitochondria function via Sirt1/AMPK/PGC1α pathways in HFD rats. This study suggested that Lira alleviated HFD-induced kidney injury at least partly via directly restoring renal metabolism, thus GLP-1R agonist is a promising therapy for obesity-associated CKD.

Oleic acid protects saturated fatty acid mediated lipotoxicity in hepatocytes and rat of non-alcoholic steatohepatitis

ABSTRACT Aim This study aims to demonstrate the protective effects of monounsaturated oleic acid (OA) against saturated palmitic acid (PA) induced cellular lipotoxicity in hepatocytes and rats with non‐alcoholic steatohepatitis (NASH). Main methods: Human hepatoma cell line HepG2 cells and neonatal rat primary hepatocytes were treated with PA or/and OA for 24 h. SD rats were fed with high fat diet (HFD) to induce NASH. From the 16th w, the HFD was full or half replaced by olive oil to observe the protective effects. Key findings: In vitro, OA substantially alleviated PA induced cellular apoptosis, oxidative stress, ER stress, mitochondrial dysfunction, as well as inflammation in hepatocytes. In vivo, only olive oil supplementation had no detrimental effects, while HFD developed NASH in normal rats. Full replacement of HFD with olive oil had profoundly reversed NASH. Noteworthily, half replacement of HFD with olive oil (a mixed diet) has ameliorated NASH injury as well. It strikingly changed the hepatic histology from macrovesicular‐steatosis into entire microvesicular‐steatosis, and significantly reduced inflammation, ballooning and fibrosis. Significance: Our study has demonstrated in both hepatocytes and NASH rats that oleic acids had great potential to combat the saturated fatty acids induced hepatic lipotoxicity. Only half replacement of HFD by monounsaturated fatty acids rich diet still had significant therapeutic outcome in NASH rats. Redirecting the toxic saturated fatty acids into triglyceride storage and reduction of cholesterol accumulation might be the possible explanation of OA driven protection in this scenario. Graphical abstract: Figure. No caption available.

Gene expression profile of vascular ischemia-reperfusion injury in rhesus monkeys

UNLABELLED The vascular system particularly endothelium is sensitive to ischemia-reperfusion (I/R) injury, which is a big challenge in surgical practices and many vascular disorders. In the present study, we reported the global gene expression changes in a 2-h ischemia and 4-h reperfusion injury induced in the hind limb vessels of rhesus monkeys (Macaca mulatta) using microarray technique. RESULTS The histological results showed abnormal morphology of endothelial cells after 2-h ischemia and the hematological detection found slightly extension of coagulation time after I/R treatment. Furthermore, we found distinct alterations in gene expression patterns during I/R process. These identified genes are mostly involved in inflammation, immune response, apoptosis, and cell stress signaling pathways. The significantly up-regulated genes included IL-6, regulator of G-protein signaling 8, selectin E, and metallothionein 2A, et al. Whist, the robustly down-regulated genes included NECAP endocytosis associated 2, transglutaminase 2, and fibronectin 1, et al. CONCLUSION Our results indicate that inflammation, primarily characterized by gene expression changes of cytokines and chemokines is the most important event in the early stage of I/R injury in blood vessels.

Immunomodulatory effects of rhesus monkey bone marrow-derived mesenchymal stem cells in serum-free conditions

ABSTRACT Mesenchymal stem cells (MSCs) have generated tremendous interest for treating various diseases due to their self‐renewal and differentiation capacities. Many studies have demonstrated the immunoregulatory capability of MSCs; however, most of these studies were conducted with fetal bovine serum (FBS), which has an uncertain composition. In this study, we established a serum‐free, xeno‐free, completely chemically defined medium for the proliferation and expansion of rhesus monkey bone marrow (BM)‐derived MSCs (rBMSCs) in vitro. The growth kinetics, characteristics, immunophenotype, and immunosuppressive abilities of rBMSCs grown in serum‐free media (SFM) were evaluated and compared with those of cells grown in serum‐containing media (SCM). Moreover, we employed RNA sequencing to evaluate the expression pattern of genes related to immune responses in both culture conditions. Compared to cells grown in SCM, rBMSCs grown in SFM exhibited better biological characteristics regarding cell proliferation and immunosuppressive abilities. Cells from both media types exhibited similar immunophenotypic expression patterns for CD29, CD34, CD45, HLA‐DR, CD73, CD90, and CD105. Gene Ontology (GO) terms, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and Gene Set Enrichment Analysis (GSEA) revealed that CXCL8 was downregulated by 4.1 fold in SFM‐cultured rBMSCs compared with those in SCM. Furthermore, the mixed lymphocyte culture revealed that the proliferation activity and the expression levels of inflammatory factors of peripheral blood mononuclear cells (PBMCs) were significantly decreased after the addition of the CXCL8 neutralizing antibody, which was related to the elevated immunosuppressive abilities of SFM‐suspended rBMSCs. These results suggest a possible cell culture method as well as immunoregulatory mechanisms for clinical cell therapies requiring nonanimal‐derived components. Graphical abstract Figure. No Caption available. HighlightsSerum‐free media improve the biological characteristics of rBMSCs.rBMSCs cultured in serum‐free media exhibit better immunosuppressive effects.The reduction of CXCL8 expressed by rBMSCs is associated with stronger Immunomodulatory abilities in serum free conditions.

Changes in advanced glycation end products, beta-defensin-3, and interleukin-17 during diabetic periodontitis development in rhesus monkeys:

The bidirectional relationship between diabetes mellitus (DM) and periodontal disease has drawn great attention; however, the mechanisms underlying their association remain unclear. In this study, we aimed to develop a rhesus monkey model of diabetic periodontitis and explore the potential mechanisms by which DM affects the progression of periodontal disease. Three healthy rhesus monkeys were selected as the control group. Five streptozotocin-induced diabetic rhesus monkeys were chosen as the experimental group. Ligature placement was used to induce periodontitis. The changes in the levels of advanced glycation end products (AGEs), beta-defensin-3 (BD-3), and interleukin-17 (IL-17) were measured using enzyme-linked immunosorbent assays (ELISA) and real-time reverse transcription polymerase chain reaction (RT-PCR) at different stages during disease progression. Periodontitis was confirmed by clinical assessment, radiographic images, and histological examination. Significant changes in the levels of AGEs and BD-3 in serum were observed at the periodontitis stage in diabetic rhesus monkeys (P < 0.05). The expression of BD-3 mRNA in the gingiva of diabetic group at baseline was significantly high (P < 0.05). Diabetic monkeys exhibited significantly enhanced IL-17 mRNA expression at the periodontitis stage (P < 0.05). Our findings indicated that the rhesus monkey can serve as an ideal model for exploring the pathogenesis of diabetic periodontitis, and the hyperglycemic environment may accelerate inflammatory response and weaken the defense system in periodontal tissues. Impact statement The mechanism underlying the association between diabetes mellitus (DM) and periodontal disease is not yet fully understood. Hence, there is a need to establish animal models to reveal the effect of DM on the pathogenesis of periodontitis. In this study, we explored the appropriate methods for inducing periodontitis and shortening the modeling time in rhesus monkeys, to investigate the pathogenesis of diabetic periodontitis and develop innovative therapies. Our results suggest that a hyperglycemic environment might lead to the destruction of periodontal tissues by accelerating inflammatory response and weakening the defense system in periodontal tissues. Therefore, this study has significant treatment implications regarding the regulation of the immune response against periodontal diseases in patients with DM.

Mesenchymal stem cells ameliorate hyperglycemia-induced endothelial injury through modulation of mitophagy

Mitochondrial dysfunction and excessive mitochondrial reactive oxygen species (ROS) are fundamental contributors to endothelial injury in diabetic states. Mesenchymal stem cells (MSCs) have exhibited an extraordinary cytoprotective effect that extends to the modulation of mitochondrial homeostasis. However, the underlying mechanisms have not been clearly defined. Emerging evidence has suggested that mitophagy could counteract mitochondrial-derived oxidative stress through the selective elimination of impaired or dysfunctional mitochondria. Therefore, we investigated whether MSCs could ameliorate high-glucose-induced endothelial injury through the modulation of mitophagy. We observed that exposure of human umbilical vein endothelial cells (HUVECs) to high glucose triggers mitochondrial impairment with excessive mitochondrial fragmentation and ROS generation, loss of membrane potential and reduced ATP production. Furthermore, mitophagy was blunted upon high glucose insult, which accelerated dysfunctional mitochondrial accumulation, initiating the mitochondrial apoptotic pathway and, eventually, endothelial dysfunction. MSCs treatment notably attenuated these perturbations accompanied by an enhancement of Pink1 and Parkin expression, whereas these beneficial effects of MSCs were abolished when either Pink1 or Parkin was knocked down. In aortas of diabetic rats, defective mitophagy was observed, which coincided with marked mitochondrial dysfunction. Ultrastructurally, RAECs from diabetic rats revealed a significant reduction in autophagic vacuoles and a marked increase in fragmented mitochondria. Importantly, the infusion of MSCs restored Pink1/Parkin-mediated mitophagy, ameliorated mitochondrial dysfunction and attenuated apoptosis in endothelial cells in diabetic rats. These results suggest that MSCs may protect endothelial cells from hyperglycemia-induced injury by ameliorating mitochondrial dysfunction via Pink1/Parkin –mediated mitophagy

GLP-1 receptor agonist ameliorates obesity-induced chronic kidney injury via restoring renal lipid and energy metabolism homeostasis: revealed by metabolomics

Increasing evidence indicate that obesity is highly associated with chronic kidney disease (CKD).GLP-1 receptor (GLP-1R) agonist has shown benefits on kidney diseases, but its direct role on kidney metabolism in obesity is still not clear. This study aims to investigate the protection and metabolic modulation role of liraglutide (Lira) on kidney of obesity. Rats were induced obese by high-fat diet (HFD), and renal function and metabolism changes were evaluated by metabolomic, biological and histological methods. HFD rats exhibited metabolic disorders including elevated body weight, hyperlipidemia and impaired glucose tolerance, and remarkable renal injuries including declined renal function and inflammatory/fibrotic changes, whereas Lira significantly ameliorated these adverse effects in HFD rats. Metabolomic data showed that Lira reduced renal lipids including fatty acid residues, cholesterol, phospholipids and triglycerides, and improved mitochondria metabolites such as succinate, citrate, taurine, fumarate and NAD+ in the kidney of HDF rats. Furthermore, we revealed that Lira inhibited renal lipid accumulation by coordinating lipogenic and lipolytic signals, and rescued renal mitochondria function via Sirt1/AMPK/PGC1α pathways in HDF rats. This study suggested that Lira alleviated HFD-induced kidney injury via directly restoring renal lipid and energy metabolism, and GLP-1 receptor agonist is a promising therapy for obesity-associated CKD.

Glucocorticoid treatment facilitates development of a metabolic syndrome in ovariectomized Macaca Mulatta fed a high fat diet

HighlightsWe reported for the first time that the endocrine and physiological changes in response to chronic and high dose of GCs in non‐human primates, and the effects of withdrawal of a long‐term treatment, which led to recovery from metabolic disorders.We used ovariectomized monkeys to mimic the situation of perimenopausal and postmenopausal women, and might be used as potential models of Cushing’s syndrome or MetS in non‐human primates.The lipid and glucose related factors including leptin and GLUT4 play important roles in the GCs effect. Abstract Metabolic syndrome (MetS) is characterized by a cluster of key features, which include abdominal obesity, insulin resistance, hypertension, and dyslipidemia. The aim of this study was to assess the impact of elevated glucocorticoid levels on the development of MetS in middle‐aged female rhesus monkeys (Macaca Mulatta) after ovariectomy. Six female ovariectomized rhesus monkeys (9–13 years) were randomly assigned to either a control group (normal diet, n = 3) or a group in which MetS was facilitated (n = 3). The MetS group fed with HFD (15% fat) and received oral prednisone acetate treatment (50 mg/day). After 24 months, the GCs treatment was withdrawn with continuation of high‐fat feeding for a further 12 months. After 24 months, the MetS group displayed a significant increase in body weight and abdominal circumference. Additionally, the MetS animals displayed abnormal serum lipids, insulin resistance and impaired glucose tolerance. Histology of liver biopsies indicated marked accumulation of lipid droplets in hepatocytes of MetS animals. Withdrawal of GCs treatment led to recovery from above‐mentioned metabolic disorders. Whereas GCs treatment increased leptin expression, it lowered expression of adiponectin and other factors in adipose tissue. Expression of Hydroxy‐steroid dehydrogenase‐1 and glucose transporter type‐4 in the livers of MetS animals were reduced. We conclude that in the context of high fat diet, high levels of exogenous GCs contribute to the development of MetS in non‐human primates.