Myeloid peroxisome proliferator-activated receptor α deficiency accelerates liver regeneration via IL-6/STAT3 pathway after 2/3 partial hepatectomy in mice

Background:Liver regeneration is a fundamental process for sustained body homeostasis and liver function recovery after injury.Emerging evidence demonstrates that myeloid cells play a critical role in liver regeneration by secreting cytokines and growth factors.Peroxisome proliferator-activated receptorα(PPARα),the target of clinical lipid-lowering fibrate drugs,regulates cell metabolism,proliferation,and survival.However,the role of myeloid PPARαin partial hepatectomy(PHx)-induced liver regeneration remains unknown.Methods:Myeloid-specific PPARa-deficient(Ppara^(Mye−/−))mice and the littermate controls(Ppara^(fl/fl))were subjected to sham or 2/3 PHx to induce liver regeneration.Hepatocyte proliferation and mitosis were assessed by immunohistochemical(IHC)staining for 5-bromo-2'-deoxyuridine(BrdU)and Ki67 as well as hematoxylin and eosin(H&E)staining.Macrophage and neutrophil infiltration into livers were reflected by IHC staining for galectin-3 and myeloperoxidase(MPO)as well as flow cytometry analysis.Macrophage migration ability was evaluated by transwell assay.The mRNA levels for cell cycle or inflammation-related genes were measured by quantitative real-time RT-PCR(qPCR).The protein levels of cell proliferation related protein and phosphorylated signal transducer and activator of transcription 3(STAT3)were detected by Western blotting.Results:Ppara^(Mye−/−)mice showed enhanced hepatocyte proliferation and mitosis at 32 h after PHx compared with Ppara^(fl/fl)mice,which was consistent with increased proliferating cell nuclear antigen(Pcna)mRNA and cyclinD1(CYCD1)protein levels in Ppara^(Mye−/−)mice at 32 h after PHx,indicating an accelerated liver regeneration in Ppara^(Mye−/−)mice.IHC staining showed that macrophages and neutrophils were increased in Ppara^(Mye−/−)liver at 32 h after PHx.Livers of Ppara^(Mye−/−)mice also showed an enhanced infiltration of M1 macrophages at 32 h after PHx.In vitro,Ppara-deficient bone marrow-derived macrophages(BMDMs)exhibited markedly enhanced migratory capacity and upregulated M1 genes Il6 and Tnfa but downregulated M2 gene Arg1 expressions.Furthermore,the phosphorylation of STAT3,a key transcript factor mediating IL6-promoted hepatocyte survival and proliferation,was reinforced in the liver of Ppara^(Mye−/−)mice after PHx.Conclusions:This study provides evidence that myeloid PPARαdeficiency accelerates PHx-induced liver regeneration via macrophage polarization and consequent IL-6/STAT3 activation,thus providing a potential target for manipulating liver regeneration.

Hepatic lipid homeostasis by peroxisome proliferator-activated receptor gamma 2

Peroxisome proliferator-activated receptor gamma(PPARγor PPARG)is a ligand-activated transcription factor belonging to the nuclear hormone receptor superfamily.It plays a master role in the differentiation and proliferation of adipose tissues.It has two major isoforms,PPARγ1 and PPARγ2,encoded from a single gene using two separate promoters and alternative splicing.Among them,PPARγ2 is most abundantly expressed in adipocytes and plays major adipogenic and lipogenic roles in the tissue.Furthermore,it has been shown that PPARγ2 is also expressed in the liver,specifically in hepatocytes,and its expression level positively correlates with fat accumulation induced by pathological conditions such as obesity and diabetes.Knockout of the hepatic Pparg gene ameliorates hepatic steatosis induced by diet or genetic manipulations.Transcriptional activation of Pparg in the liver induces the adipogenic program to store fatty acids in lipid droplets as observed in adipocytes.Understanding how the hepatic Pparg gene expression is regulated will help develop preventative and therapeutic treatments for non-alcoholic fatty liver disease(NAFLD).Due to the potential adverse effect of hepatic Pparg gene deletion on peripheral tissue functions,therapeutic interventions that target PPAR g for fatty liver diseases require fine-tuning of this gene's expression and transcriptional activity。

神经干细胞特异性PPARγ基因敲除小鼠模型的制备与鉴定

目的制备与鉴定神经干细胞特异性PPARγ基因敲除小鼠模型。方法将引进的2种转基因小鼠B6.PPARγloxp/loxp、B6.Nestin-Cre进行饲养并杂交繁殖,将子一代小鼠与B6.PPARγloxp/loxp小鼠回交获得子二代小鼠,提取子二代小鼠的基因组DNA,利用PCR方法扩增Cre和loxp基因片段,并进行琼脂糖凝胶电泳检测。选取基因型为B6.PPARγloxp/loxp.Nestin-Cre(KO)的小鼠即为神经干细胞特异性敲除PPARγ的敲除小鼠,另选基因型为B6.PPARγloxp/loxp(loxp)作为对照组小鼠。应用RT-PCR、实时荧光定量PCR方法鉴定神经干细胞特异性敲除PPARγ的敲除小鼠。结果敲除小鼠在基因鉴定时可以扩增得到PPARγloxp和Cre两个条带,在mRNA表型检测时脑内PPARγ表达显著低于对照组小鼠。成功获得神经干细胞敲除PPARγ基因的敲除小鼠。所购2种转基因小鼠均有繁殖能力,其繁殖符合孟德尔遗传规律。结论基于loxp-Cre系统成功构建神经干细胞特异性敲除PPARγ的基因敲除小鼠,为进一步的神经系统疾病的治疗及其机制研究提供模型基础。

Effect of Marine Collagen Peptides on Markers of Metabolic Nuclear Receptors in Type 2 Diabetic Patients with/without Hypertension

Objective To explore Effects of marine collagen peptides （MCPs） on markers of metablic nuclear receptors, i.e peroxisome proliferator-activated receptor （PPARs）, liver X receptor （LXRs） and farnesoid X receptor （FXRs） in type 2 diabetic patients with/without hypertension. Method Study population consisted of 200 type 2 diabetic patients with/without hypertension and 50 healthy subjects, all of whom were randomly assigned to MCPs-treated diabetics （n=50）, placebo-treated diabetics （n=50）, MCPs-treated diabetics with hypertension （n=50）, placebo-treated diabetics with hypertension （n=50）, and healthy controls （n=50）. MCPs or placebo （water-soluble starch） were given daily before breakfast and bedtime over three months. Levels of free fatty acid, cytochrome P450, leptin, resistin, adiponectin, bradykinin, NO, and Prostacyclin were determined before intervention, and 1.5 months, and 3 months after intervention. Hypoglycemia and the endpoint events during the study were recorded and compared among the study groups. Result At the end of the study period, MCPs-treated patients showed marked improvement compared with patients receiving placebo. The protection exerted by MCPs seemed more profound in diabetics than in diabetics with hypertension. In particular, after MCPs intervention, levels of free fatty acid, hs-CRP, resistin, Prostacyclin decreased significantly in diabetics and tended to decrease in diabetic and hypertensive patients whereas levels of cytochrome P450, leptin, NO tended to decrease in diabetics with/without hypertension. Meanwhile, levels of adiponectin and bradykinin rose markedly in diabetics following MCPs administration. Conclusion MCPs could offer protection against diabetes and hypertension by affecting levels of molecules involved in diabetic and hypertensive pathogenesis. Regulation on metabolic nuclear receptors by MCPs may be the possible underlying mechanism for its observed effects in the study. Further study into its action may shed light on development of new drugs based on bioactive peptides from marine sources.

Anticancer actions of PPARγ ligands:Current state and future perspectives in human lung cancer

Peroxisome proliferator-activated receptors(PPARs) are ligand-dependent nuclear transcription factors and members of the nuclear receptor superfamily.Of the three PPARs identified to date(PPARγ,PPARβ/δ,and PPARα),PPARγ has been studied the most,in part because of the availability of PPARγagonists(also known as PPARγ ligands)and its significant effects on the management of several human diseases including type 2 diabetes,metabolic syndrome,cardiovascular disease and cancers.PPARγ is expressed in many tumors including lung cancer,and its function has been linked to the process of lung cancer development, progression and metastasis.Studies performed in gynogenic and xenograft models of lung cancer showed decreased tumor growth and metastasis in animals treated with PPARγ ligands.Furthermore,data are emerging from retrospective clinical studies that suggest a protective role for PPARγ ligands on the incidence of lung cancer.This review summarizes the research being conducted in this area and focuses on the mechanisms and potential therapeutic effects of PPARγ ligands as a novel anti-lung cancer treatment strategy.

Design,synthesis and in vitro evaluation of a series thiazolidinediones analogs as PPAR modulators

A series of thiazolidinediones analogs, as PPAR modulators, were designed, synthesized and evaluated in vitro.

LXR, PPAR<i>γ</i>, and PPAR<i>δ</i>Agonists Are Not Sufficient to Demonstrate Therapeutic Potential against Mouse Model of Systemic Lupus Erythematosus

Aim: We aimed to investigate whether the agonists for liver X receptor (LXR) ameliorate lupus-like phenotypes in mice mediated by the clearance of apoptotic cells, and compare with peroxisome proliferator-activated receptor (PPAR) γ plus PPARδ agonists, which also facilitate the clearance of apoptotic cells and exert anti-inflammatory effects in systemic lupus erythematosus (SLE). Methods: We investigated the efficacy of LXR agonist (GW3965) or dual treatment of PPARγ (pioglitazone) and PPARδ (GW0742) agonists in SLE animal models, female MRL/MpJ-Fas/J mice and BALB/cAJcl mice treated with pristane. The data were analyzed with one-way analysis of variance and Tukey’s honestly significant difference tests. Results: The treatment with LXR or PPARγ/δ agonists did not significantly alter the swelling of lymph nodes, ds-DNA production, albuminuria, histological score of glomerular lesions, and mRNA expression of target genes including Abca1, C1qa, Icam1, Mertk and Tnf. Conclusion: LXR or PPARγ/δ agonists targeting the impaired clearance for apoptosis cells may not be efficient in the remission induction therapy in SLE.

脓毒症研究新进展

脓毒症正逐渐成为全世界严峻的医学问题，脓毒症的发病率与病死率逐年上升，然而脓毒症的临床治疗并未取得理想的效果，可能归咎于其复杂的病理生理过程和尚未完全揭示的发病机制。近年来研究发现，氧化还原反应失衡、过氧化物酶增生物激活受体的功能下降、补体的激活与释放、神经调节紊乱、免疫麻痹等参与了脓毒症的发病机制，有助于我们对脓毒症的进一步认识。至此，本文将对这些新机制加以综述。

Effect of mango seed kernel extract on the adipogenesis in 3T3-L1 adipocytes and in rats fed a high fat diet

Mangoes (Mangifera indica L.) are one of the most important tropical foods. The seed is one of the main by-products of mango processing. Therefore, it is important to find an economically viable use for this waste (e.g., as a food additive or supplement with high nutraceutical value). We investigated the anti-obesity effects of mango seed kernel extract with hot water (MSKE-W) in 3T3-L1 adipocytes and in a high fat diet (HFD)-induced obesity rat model. MSKE-W caused a significant decrease in the activity of glycerol 2-phosphate dehydrogenase in 3T3-L1 adipocytes without eliciting cell cytotoxicity and inhibited cellular lipid accumulation through down-regulation of transcription factors such as PPARγ and C/EBPα. In the animal model, rats fed an HFD containing 1% MSKE-W gained less weight than rats fed an HFD alone. The visceral fat mass in rats fed an HFD containing 1% MSKE-W tended to be lower than that in rats fed an HFD alone. Furthermore, histological examination of rat livers from an HFD showed steatohepatitis. However, rats on an HFD containning 1% MSKE-W showed no histopathological changes in liver tissue. Our results indicate that MSKE-W influences anti-obesity effects, both in vitro and in vivo, and suggest that MSKE-W provides a novel preventive potential against obesity.

Role of melatonin receptor 1B gene polymorphism and its effect on the regulation of glucose transport in gestational diabetes mellitus

Melatonin receptor 1B(MT2,encoded by the MTNR1B gene),a high-affinity receptor for melatonin,is associated with glucose homeostasis including glucose uptake and transport.The rs10830963 variant in the MTNR1B gene is linked to glucose metabolism disorders including gestational diabetes mellitus(GDM);however,the relationship between MT2-mediated melatonin signaling and a high birth weight of GDM infants from maternal glucose abnormality remains poorly understood.This article aims to investigate the relationship between rs10830963 variants and GDM development,as well as the effects of MT2 receptor on glucose uptake and transport in trophoblasts.TaqMan-MGB(minor groove binder)probe quantitative realtime polymerase chain reaction(qPCR)assays were used for rs10930963 genotyping.MT2 expression in the placenta of GDM and normal pregnant women was detected by immunofluorescence,western blot,and qPCR.The relationship between MT2 and glucose transporters(GLUTs)or peroxisome proliferator-activated receptorγ(PPARγ)was established by western blot,and glucose consumption of trophoblasts was measured by a glucose assay kit.The results showed that the genotype and allele frequencies of rs10830963 were significantly different between GDM and normal pregnant women(P<0.05).The fasting,1-h and 2-h plasma glucose levels of G-allele carriers were significantly higher than those of C-allele carriers(P<0.05).Besides,the protein and messenger RNA(mRNA)expression of MT2 in the placenta of GDM was significantly higher than that of normal pregnant women(P<0.05).Melatonin could stimulate glucose uptake and GLUT4 and PPARγprotein expression in trophoblasts,which could be attenuated by MT2 receptor knockdown.In conclusion,the rs10830963 variant was associated with an increased risk of GDM.The MT2 receptor is essential for melatonin to raise glucose uptake and transport,which may be mediated by PPARγ.

Sub-nanosized vanadate hybrid clusters maintain glucose homeostasis and restore treatment response in inflammatory disease in obese mice

Obesity is closely related with insulin resistance and chronic inflammation.Here,we report that unsaturated lipid-modified polyoxovanadates(ULPOVs)can restrict weight gain of diet-induced obese mice and improve their glycemic control and obesity-associated inflammation.Oral administration of the sub-nanosized ULPOVs at a low dosage for 7 weeks reduces the body weight and almost normalizes the blood glucose levels of obese mice fed on a high-fat diet.ULPOV treatment increases the activity of the nuclear receptor peroxisome proliferator-activated receptorγ(PPARγ)and reduces intestinal caloric intake,which may be the main reason for blood sugar and body weight control.In addition to insulin-sensitizing,PPARγactivation induced by ULPOV treatment in obese mice with atopic dermatitis(AD)promotes the type 2 T helper(TH_(2))cell selective responses and therapeutic effects on immune dysregulation caused by obesity.These data suggest sub-nanosized polyoxovanadate clusters as a class of potential candidates to relieve symptoms accompanied by diet-induced obesity.

Natural products,PGC-1α,and Duchenne muscular dystrophy

Peroxisome proliferator-activated receptorγ(PPARγ)is a transcriptional coactivator that binds to a diverse range of transcription factors.PPARγcoactivator 1(PGC-1)coactivators possess an extensive range of biological effects in different tissues,and play a key part in the regulation of the oxidative metabolism,consequently modulating the production of reactive oxygen species,autophagy,and mitochondrial biogenesis.Owing to these findings,a large body of studies,aiming to establish the role of PGC-1 in the neuromuscular system,has shown that PGC-1 could be a promising target for therapies targeting neuromuscular diseases.Among these,some evidence has shown that various signaling pathways linked to PGC-1αare deregulated in muscular dystrophy,leading to a reduced capacity for mitochondrial oxidative phosphorylation and increased reactive oxygen species(ROS)production.In the light of these results,any intervention aimed at activating PGC-1 could contribute towards ameliorating the progression of muscular dystrophies.PGC-1αis influenced by different patho-physiological/pharmacological stimuli.Natural products have been reported to display modulatory effects on PPARγactivation with fewer side effects in comparison to synthetic drugs.Taken together,this review summarizes the current knowledge on Duchenne muscular dystrophy,focusing on the potential effects of natural compounds,acting as regulators of PGC-1α.

The metabolite, alpha-ketoglutarate inhibits non-alcoholic fatty liver disease progression by targeting lipid metabolism

Background:Non-alcoholic liver disease is of increased concern and contributing to economic burdens not only in developing countries but in developed countries as well.Identifying the biomarker of early diagnosis and early intervention approaches for non-alcoholic liver disease is unmet and required further investigation.Although the alpha-ketoglutarate(a-KG)is recently proposed to be a potential biomarker in differentiating patients with obesity from those with non-alcoholic liver disease,how a-ketoglutatate is involved in the fatty liver progression is not clear.Methods:A high-fat diet(HFD)feeding animal model,liver functional assays,and molecular approaches were adopted to clarify the impact of a-KG in fatty liver progression.Results:In the current study,it was found that dietary a-KG would inhibit weight gain in male and female mice fed with a normal chew or HFD.HFD feeding caused fatty liver in male mice,but a-KG treatment could substantially inhibit hepatic steatosis progression.Biochemical studies revealed the possible linkage of a-KG protective functions to lipid metabolism.Further analysis identified the important role of peroxisome proliferator-activated receptors in beneficial a-KG-mediated effects on fatty liver progression.Conclusions:The current study demonstrates the therapeutic potential of a-KG and how it may be used,via dietary supplementation,as a preventive intervention for non-alcoholic liver disease in obese patients.