Development of a dietary-induced metabolic syndrome model using miniature pigs involvement of AMPK and SIRT1

Determination of mitochondrial functions and damage in kidney in female LeeSung minipigs with a high-fat diet-induced obesity

The purpose of this study was to investigate the nexus between mitochondrial function and kidney injury by using a dietary-induced obese minipig model. Female Lee-Sung minipigs feeding a high-fat diet (HFD) for 6 months exhibited obesity, hyperglycaemia and dyslipidemia. HFD elevated the levels of plasma biomarkers related to renal injury, including symmetric dimethylarginine, creatinine and urea nitrogen. An extensive structural change in tubules and glomeruli was observed in HFD-fed pigs. A great amount of triacylglycerol was accumulated in HFD kidney compared to control kidney, whereas a reduction of ATP level and antioxidant capacity were exhibited in HFD kidney. Moreover, HFD altered the expressions of mitochondrial-related protein in renal cortex. To conclude, long-term HFD feeding to Lee-Sung minipigs induced obesity and kidney injury accompanied by abnormal mitochondrial functions in the renal cortex, suggesting an interrelationship with renal disease progression.

High-fidelity porcine models of metabolic syndrome: a contemporary synthesis

This review aims to describe and compare porcine models of metabolic syndrome. This syndrome and its associated secondary comorbidities are set to become the greatest challenge to healthcare providers and policy makers in the coming century. However, an incomplete understanding of the pathogenesis has left significant knowledge gaps in terms of efficacious therapeutics. To further our comprehension and, in turn, management of metabolic syndrome, appropriate high-fidelity models of the disease complex are of great importance. In this context, our review aims to assess the most promising porcine models of metabolic syndrome currently available for their similarity to the human phenotype. In addition, we aim to highlight the strengths and shortcomings of each model in an attempt to identify the most appropriate application of each. Although no porcine model perfectly recapitulates the human metabolic syndrome, several pose satisfactory approximations. The Ossabaw miniature swine in particular represents a highly translatable model that develops each of the core parameters of the syndrome with many of the associated secondary comorbidities. Future high-fidelity porcine models of metabolic syndrome need to focus on secondary sequelae replication, which may require extended induction period to reveal.

Early-onset dietary restriction maintains mitochondrial health, autophagy and ER function in the left ventricle during aging

Dietary restriction (DR) exerts healthy benefits, including heart functions. However, the cardioprotective role of DR is till controversial among researchers due to the variation of DR conditions. The present study focuses on the protective effect of early-onset DR on cardiac injury using mitochondrial structure and expression of protein associated with mitochondrial homeostasis, autophagy and endoplasmic reticulum (ER) function as measures.

METHODS

Two-month-old mice were fed with a breeding diet ad libitum (AL) or DR (60% of AL) for 3 (Young) or 20 (Aged) months.

RESULTS

Body weight increased with aging, whereas DR treatment kept body weight consistent. DR mice exhibited a higher relative heart weight than AL mice. DR mice displayed lower plasma glucose levels, compared with AL groups. Furthermore, Aged-AL, but not Aged-DR mice, had increased collagen content and morphological distortions in the left ventricle (LV). Aged-DR mice had a higher ATP and lower TBARS in the LV than Aged-AL mice. Mitochondrial morphology was detected by electron microscopy; Aged-AL mice had increased abnormal morphology of mitochondria. Treatment with DR reduced abnormal mitochondrial accumulation. Aging elevated the protein expressions of mitochondrial functions and ER-induced apoptosis. Aging downregulated autophagy-related proteins and chaperones in the heart. Dietary restriction reversed those protein expressions.

CONCLUSIONS

The present study demonstrated a beneficial effect of early onset DR on cardiac aging. The age-dependent mitochondrial dysfunction and protein quality control dysregulation was significantly reversed by long-term DR, demonstrating a concordance with the beneficial effect in the heart.

Translational model of vein graft failure following coronary artery bypass graft in atherosclerotic microswine

OBJECTIVE

Vein graft failure is a major complication following coronary artery bypass graft surgery. There is no translational model to understand the molecular mechanisms underlying vein-graft failure. We established a clinically relevant bypass graft model to investigate the underlying pathophysiological mechanisms of vein-graft failure and identify molecular targets for novel therapies.

METHODS

Six female Yucatan microswine fed with high cholesterol diet underwent off-pump bypass, using superficial epigastric vein graft, which was anastomosed to an internal mammary artery and distal left anterior descending artery. Vein-graft patency was examined 10-months after bypass surgery by echocardiography, coronary angiography, and optical coherence tomography followed by euthanasia. Coronary tissues were collected for histomorphometry studies.

RESULTS

Atherosclerotic microswine were highly susceptible to sudden ventricular fibrillation with any cardiac intervention. Two out of six animals died during surgery due to ventricular fibrillation. Selection of the anesthetics and titration of their doses with careful use of inotropic drugs were the key to successful swine cardiac anesthesia. The hypotensive effects of amiodarone and the incidence of arrhythmia were avoided by the administration of magnesium sulfate. The vein-graft control tissue displayed intact endothelium with well-organized medial layer. The grafted vessels revealed complete occlusion and were covered with fibrous tissues. Expression of CD31 in the graft was irregular as the layers were not clearly defined due to fibrosis.

CONCLUSION

This model represents the clinical vein-graft failure and offers a novel platform to investigate the underlying molecular mechanisms of vein-graft disease and investigate novel therapeutic approaches to prevent its progression.

The Critical Role of SIRT1 in Parkinson's Disease: Mechanism and Therapeutic Considerations

Silence information regulator 1 (SIRT1), a member of the sirtuin family, targets histones and many non-histone proteins and participates in various physiological functions. The enzymatic activity of SIRT1 is decreased in patients with Parkinson’s disease (PD), which may reduce their ability to resist neuronal damage caused by various neurotoxins. As far as we know, SIRT1 can induce autophagy by regulating autophagy related proteins such as AMP-activated protein kinase, light chain 3, mammalian target of rapamycin, and forkhead transcription factor 1. Furthermore, SIRT1 can regulate mitochondrial function and inhibit oxidative stress mainly by maintaining peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) in a deacetylated state and thus maintaining a constant level of PGC-1α. Other studies have demonstrated that SIRT1 may play a role in the pathophysiology of PD by regulating neuroinflammation. SIRT1 deacetylases nuclear factor-kappa B and thus reduces its transcriptional activity, inhibits inducible nitric oxide synthase expression, and decreases tumor necrosis factor-alpha and interleukin-6 levels. SIRT1 can also upregulate heat shock protein 70 by deacetylating heat shock factor 1 to increase the degradation of α-synuclein oligomers. Few studies have focused on the relationship between SIRT1 single nucleotide polymorphisms and PD risk, so this topic requires further research. Based on the neuroprotective effects of SIRT1 on PD, many in vitro and in vivo experiments have demonstrated that some SIRT1 activators, notably resveratrol, have potential neuroprotective effects against dopaminergic neuronal damage caused by various neurotoxins. Thus, SIRT1 plays a critical role in PD development and might be a potential target for PD therapy.

Swine Disease Models for Optimal Vascular Engineering

Swine disease models are essential for mimicry of human metabolic and vascular pathophysiology, thereby enabling high-fidelity translation to human medicine. The worldwide epidemic of obesity, metabolic disease, and diabetes has prompted the focus on these diseases in this review. We highlight the remarkable similarity between Ossabaw miniature swine and humans with metabolic syndrome and atherosclerosis. Although the evidence is strongest for swine models of coronary artery disease, findings are generally applicable to any vascular bed. We discuss the major strengths and weaknesses of swine models. The development of vascular imaging is an example of optimal vascular engineering in swine. Although challenges regarding infrastructure and training of engineers in the use of swine models exist, opportunities are ripe for gene editing, studies of molecular mechanisms, and use of swine in coronary artery imaging and testing of devices that can move quickly to human clinical studies.

The impact of DRP1 on myocardial fibrosis in the obese minipig

BACKGROUND

The heart is a highly oxidative tissue, thus mitochondria play a major role in maintaining optimal cardiac function. Our previous study established a dietary-induced obese minipig with cardiac fibrosis. The aim of this study was to elucidate the role of mitochondrial dynamics in cardiac fibrosis of obese minipigs.

DESIGN

Four-month-old Lee-Sung minipigs were randomly divided into two groups: a control group (C) and an obese group (O) by feeding a control diet or a high-fat diet (HFD) for 6 months. Exposure of H9c2 cardiomyoblasts to palmitate was used to explore the effects of high-fat on induction of myocardial injury in vitro.

RESULTS

The O pigs displayed greater heart weight and cardiac collagen accumulation. Obese pigs exhibited a lower antioxidant capacity, ATP concentration, and higher oxidative stress in the left ventricle (LV). The HFD caused downregulation in protein expression of PGC-1α and OPA1, and upregulation of DRP1, FIS1, and PINK1 in the LV of O compared to C pigs. Furthermore, palmitate induced apoptosis and decreased ATP content in H9c2 cells. Palmitate elevated the protein expression of DRP1 and PINK1 in these cells. Inhibition of DRP1 protein expression by siDRP1 in H9c2 cells resulted in enhanced ATP and decreased palmitate-induced apoptosis.

CONCLUSIONS

These results suggest that mitochondrial dynamics were linked to the progression of obesity-related cardiac injury. Inhibition of DRP1 after palmitate exposure in H9c2 cells resulted in improved ATP level and decreased apoptosis in vitro suggesting that mitochondrial fission serves a key role in progression of obesity-induced cardiac fibrosis.

Gut microbiome of a porcine model of metabolic syndrome and HF-pEF

Metabolic syndrome (MetS) is a composite of cardiometabolic risk factors, including obesity, dyslipidemia, hypertension, and insulin resistance, with a range of secondary sequelae such as nonalcoholic fatty liver disease and diastolic heart failure. This syndrome has been identified as one of the greatest global health challenges of the 21st century. Herein, we examine whether a porcine model of diet- and mineralocorticoid-induced MetS closely mimics the cardiovascular, metabolic, gut microbiota, and functional metataxonomic phenotype observed in human studies. Landrace pigs with deoxycorticosterone acetate-induced hypertension fed a diet high in fat, salt, and sugar over 12 wk were assessed for hyperlipidemia, hyperinsulinemia, and immunohistologic, echocardiographic, and hemodynamic parameters, as well as assessed for microbiome phenotype and function through 16S rRNA metataxonomic and metabolomic analysis, respectively. All MetS animals developed obesity, hyperlipidemia, insulin resistance, hypertension, fatty liver, structural cardiovascular changes including left ventricular hypertrophy and left atrial enlargement, and increased circulating saturated fatty acid levels, all in keeping with the human phenotype. A reduction in α-diversity and specific microbiota changes at phylum, family, and genus levels were also observed in this model. Specifically, this porcine model of MetS displayed increased abundances of proinflammatory bacteria coupled with increased circulating tumor necrosis factor-α and increased secondary bile acid-producing bacteria, which substantially impacted fibroblast growth factor-19 expression. Finally, a significant decrease in enteroprotective bacteria and a reduction in short-chain fatty acid-producing bacteria were also noted. Together, these data suggest that diet and mineralocorticoid-mediated development of biochemical and cardiovascular stigmata of metabolic syndrome in pigs leads to temporal gut microbiome changes that mimic key gut microbial population signatures in human cardiometabolic disease.NEW & NOTEWORTHY This study extends a prior porcine model of cardiometabolic syndrome to include systemic inflammation, fatty liver, and insulin sensitivity. Gut microbiome changes during evolution of porcine cardiometabolic disease recapitulate those in human subjects with alterations in gut taxa associated with proinflammatory bacteria, bile acid, and fatty acid pathways. This clinical scale model may facilitate design of future interventional trials to test causal relationships between gut dysbiosis and cardiometabolic syndrome at a systemic and organ level.

Preparation of a new type 2 diabetic miniature pig model via the CRISPR/Cas9 system

Diabetes has become one of the major noninfectious diseases that seriously endanger public health. The formation of islet amyloid polypeptide (IAPP) affects the normal physiological functions of the body, such as glucose metabolism and lipid metabolism. The mature human IAPP protein (hIAPP) has a strong tendency to misfold and is considered to be one of the major causes of amyloid changes in islets. Deposition of hIAPP is considered to be one of the leading causes of type 2 diabetes mellitus (T2DM). Miniature pigs are experimental animal models that are well suited for research on gene function and human diabetes. In our study, we obtained IAPP gene-humanized miniature pigs via the CRISPR/Cas9 system and somatic cell nuclear transfer (SCNT) technology. The hIAPP pigs can be used to further study the pathogenesis and related complications of T2DM and to lay a solid foundation for the prevention and treatment of T2DM.

The role of pericardial adipose tissue in the heart of obese minipigs

BACKGROUND

Pericardial adipose tissue (PAT) volume is highly associated with the presence and severity of cardiometabolic diseases, but the underlying mechanism is unknown. We previously demonstrated that a high-fat diet (HFD) induced metabolic dysregulation, cardiac fibrosis and accumulation of more PAT in minipigs. This study used our obese minipig model to investigate the characteristics of PAT and omental visceral fat (VAT) induced by a HFD, and the potential link between PAT and HFD-related myocardial fibrosis.

MATERIALS AND METHODS

Five-month-old Lee-Sung minipigs were made obese by feeding a HFD for 6 months.

RESULTS

The HFD induced dyslipidemia, cardiac fibrosis and more fat accumulation in the visceral and pericardial depots. The HFD changes the fatty acid composition in the adipose tissue by decreasing the portion of linoleic acid in the VAT and PAT. No arachidonic acid was detected in the VAT and PAT of control pigs, whereas it existed in the same tissues of obese pigs fed the HFD. Compared with the control pigs, elevated levels of malondialdehyde and TNFα were exhibited in the plasma and PAT of obese pigs. HFD induced greater size of adipocytes in VAT and PAT. Higher levels of GH, leptin, OPG, PDGF, resistin, SAA and TGFβ were observed in obese pig PAT compared to VAT.

CONCLUSION

This study demonstrated the similarities and dissimilarities between PAT and VAT under HFD stimulus. In addition, this study suggested that alteration in PAT contributed to the myocardial damage.

Diet-Induced Abdominal Obesity, Metabolic Changes, and Atherosclerosis in Hypercholesterolemic Minipigs

BACKGROUND

Obesity and metabolic syndrome (MetS) are major risk factors for atherosclerotic diseases; however, a causal link remains elusive. Animal models resembling human MetS and its complications, while important, are scarce. We aimed at developing a porcine model of human MetS.

METHODS

Forty pigs with familial hypercholesterolemia were fed a high fat + fructose diet for 30 weeks. Metabolic assessments and subcutaneous fat biopsies were obtained at 18 and 30 weeks, and fat distribution was assessed by CT-scans. Postmortem, macrophage density, and phenotype in fat tissues were quantified along with atherosclerotic burden.

RESULTS

During the experiment, we observed a >4-fold in body weight, a significant but small increase in fasting glucose (4.1 mmol/L), insulin (3.1 mU/L), triglycerides (0.5 mmol/L), and HDL cholesterol (2.6 mmol/L). Subcutaneous fat correlated with insulin resistance, but intra-abdominal fat correlated inversely with insulin resistance and LDL cholesterol. More inflammatory macrophages were found in visceral versus subcutaneous fat, and inflammation decreased in subcutaneous fat over time.

CONCLUSIONS

MetS based on human criteria was not achieved. Surprisingly, visceral fat seemed part of a healthier metabolic and inflammatory profile. These results differ from human findings, and further research is needed to understand the relationship between obesity and MetS in porcine models.

The high-fat diet induces myocardial fibrosis in the metabolically healthy obese minipigs-The role of ER stress and oxidative stress

BACKGROUND

The cellular mechanisms of obesity-induced cardiomyopathy are multiple and not completely elucidated. The objective of this study was to differentiate two obesity-associated cardiomyopathy miniature pig models: one with the metabolic syndrome (MetS), and one with a metabolically healthy obesity (MHO). The cellular responses during the development of obesity-induced cardiomyopathy were investigated.

METHODS

Five-month-old Lee-Sung (MetS) and Lanyu (MHO) minipigs were made obese by feeding a high-fat diet (HFD) for 6 months.

RESULTS

Obese pigs exhibited a greater heart weight than control pigs. Interstitial and perivascular fibrosis developed in the myocardium of obese pigs. The HFD induced cardiac lipid accumulation and oxidative stress and also decreased the antioxidant defense in MetS pigs. This diet activated oxidative stress without changing cardiac antioxidant defense and lipid content in MHO pigs. The HFD upregulated the expression of Grp94, CHOP, caspase 12, p62, and LC3II, and increased the ratio of LC3II to LC3I in the left ventricle (LV) of MetS pigs. Compared to obese MetS pigs, less Grp94 and elevated CHOP expression was found in the obese MHO heart. The HFD did not change the ratio of LC3II to LC3I and p62 expression in obese MHO pigs. The obese MetS pigs had an extensive and greater inflammatory response in the plasma than the obese MHO pigs, which had a lesser and milder inflammation.

CONCLUSION

Oxidative stress and ER stress were involved in the progression of MHO-related cardiomyopathy. Inflammation, autophagy, ER stress, oxidative stress, and lipotoxicity participated in the pathological mechanism of MetS-related cardiomyopathy.

Investigating the Metabolic Syndrome: Contributions of Swine Models

The metabolic syndrome (MetS), a cluster of dyslipidemia, hypertension, and diabetes and an important contributor to cardiovascular morbidity and mortality, occurs in nearly 35% of adults and 50% of the aging population in the United States. However, the underlying mechanisms by which MetS orchestrates and amplifies cardiovascular events remain elusive. Furthermore, traditional therapeutic strategies addressing lifestyle modifications and individual components of MetS are often unsuccessful in decreasing morbidity due to MetS. The availability of an adequate experimental platform that mimics the complexity of MetS may allow development of novel management techniques. Swine models, including domestic pigs and minipigs, have made important contributions to our understanding of many aspects of MetS. Given their similarity to human anatomy and physiology, those models may have significant predictive power for elucidating the pathophysiology of MetS in a manner applicable to humans. Moreover, experimental maneuvers and drugs can be tested in these preclinical models before application in patients with MetS. This review highlights the utility of the pig as an animal model for metabolic disorders, which may play a crucial role in novel drug development to optimize management of MetS.

A nutritional nonalcoholic steatohepatitis minipig model

BACKGROUND AND AIMS

The objective of this study was to elucidate whether a Western diet was associated with nonalcoholic steatohepatitis (NASH), and the relationship between NASH, autophagy and endoplasmic reticulum (ER) stress.

METHODS

Four-month-old Lee-Sung minipigs were randomly assigned to two groups: control diet (C) and Western diet (W), for a 5-month experimental period.

RESULTS

Feeding a Western diet produced a body composition with more fat, less lean and a greater liver weight. Compared with C pigs, W pigs also exhibited an elevated level of plasma insulin and free fatty acid. The W pigs displayed glucose intolerance, lower circulation antioxidant capacity and greater hepatic oxidative stress. Furthermore, pig fed the W diets had increased collagen accumulation in the liver and elevated systemic inflammation [tumor necrosis factor α and interleukin (IL)-6]. Compared with C pigs, W pigs had higher hepatic ER stress-related protein expression of GRP94, CHOP and caspase-12. The W pigs also had greater hepatic autophagy-related protein expression of p62 and LC3II. In an obesity antibody array analysis, W pigs had higher type 2 diabetes mellitus- (insulin-like growth factor 1, osteoprotegerin and resistin), atherosclerosis- (vascular endothelial growth factor, platelet-derived growth factor-AA and plasminogen activator inhibitor-I) and inflammation- [IL-1, macrophage-stimulating protein alpha, X-linked ectodermal dysplasia receptor and serum amyloid A (SAA)] related protein expressions. In addition, W pigs had greater plasma SAA concentration than C pigs and plasma SAA level was highly associated with IL-6.

CONCLUSIONS

We successfully established a NASH pig model, and our findings suggested an association of NASH with ER stress and autophagy. The SAA has potential as a novel plasma biomarker for nonalcoholic fatty liver disease pigs.