小檗碱对损伤胰岛βTC6细胞相关信号分子表达的影响

目的:探讨小檗碱在棕榈酸(palmic acid, PA)诱导的胰岛β细胞发生凋亡时PTEN及AMPK的变化及其作用机制。方法:采用1.0 mmol/L PA诱导胰岛βTC6细胞损伤模型,然后给予小檗碱干预。采用流式细胞术检测βTC6细胞凋亡率,RT-q PCR法及免疫荧光法检测在PA及小檗碱作用下信号转导通路分子PTEN及AMPK表达的变化。结果:PA抑制βTC6细胞的生长并诱导其凋亡,小檗碱可缓解PA引起的βTC6的凋亡,对氧化应激具有保护作用;伴随着凋亡的发生,AMPK的表达显著降低,而PTEN的表达显著升高,表明细胞氧化损伤严重时抑制了AMPK的表达及转录,而PTEN在βTC6细胞的凋亡中具有促进作用;小檗碱治疗后,AMPK的表达增多,而PTEN的表达下降,暗示着小檗碱通过激活AMPK并抑制PTEN的表达来增强βTC6细胞的抗氧化能力。结论:小檗碱对PA引起的细胞凋亡有保护作用,同时小檗碱可能通过调节AMPK及PTEN的表达来发挥抗氧化作用。     

小檗碱通过抑制Traf2-MEKK1-MEK-ERK通路改善TNF-α诱导的胰岛素抵抗

目的:探讨小檗碱对肿瘤坏死因子-α(TNF-α)所致人肝癌细胞株HepG2胰岛素抵抗的缓解作用及分子机制。方法:采用10ng/m L TNF-α诱导HepG2细胞产生胰岛素抵抗,同时以1μmol/L小檗碱处理细胞,通过Western blotting检测胰岛素通路信号分子(IRS1、AKT)和TNF-α通路信号分子(Traf2、MEKK1、MEK1/2、ERK1/2)的蛋白表达。此外,通过过表达或抑制TNF-α通路的信号分子(MEK1、ERK2)进一步探讨小檗碱靶点。结果:TNF-α抑制HepG2细胞AKT(Thr308、Ser473位点)和IRS1(酪氨酸位点)的磷酸化(P0.05),促进IRS1(Ser307位点)和ERK1/2的磷酸化(P0.05),而这一作用能够被小檗碱所逆转(P0.05)。同时,TNF-α对AKT活性的抑制作用能够被ERK1/2或MEK1/2的抑制剂拮抗(P0.05)。此外,小檗碱并不能改善持续激活型ERK2(CA)或MEK1(CA)对胰岛素通路的抑制作用(P0.05),但是能阻碍Traf2与MEKK1的相互作用(P0.05)。结论:小檗碱通过抑制Traf2-MEKK1-MEK-ERK通路改善TNF-α诱导的胰岛素抵抗。     

基于蛋氨酸代谢调控的内源性抗氧化分子机制

蛋氨酸是一种含硫必需氨基酸,在蛋白质组成和新陈代谢中都发挥着独特的作用。蛋氨酸具有内源性抗氧化作用,一方面蛋氨酸在蛋氨酸亚砜还原酶(MSR)作用下通过自身氧化还原反应来发挥内源性抗氧化作用,另一方面蛋氨酸可通过代谢途径(GSH合成、Nrf2抗氧化通路等)来增强内源性抗氧化能力。然而目前缺乏对蛋氨酸抗氧化分子机制全面深入的研究报道。因此,本文在蛋氨酸代谢的基础上,对蛋氨酸促进GSH合成、激活MSR抗氧化系统以及调控Nrf2抗氧化通路的分子机制进行综述,并对GSH合成、MSR与Nrf2抗氧化体系之间的关系进行阐述,为全面解析蛋氨酸内源性抗氧化分子机制提供理论依据。     

小檗碱对乳腺癌MDA-MB-231细胞增殖抑制作用及其分子机制研究

本研究的目的是为了探索小檗碱对乳腺癌MDA-MB-231细胞增殖的影响以及阐明小檗碱促乳腺癌细胞凋亡的分子机制。在实验过程中,我们通过MTT检测小檗碱对乳腺癌MDA-MB-231细胞增殖的抑制作用,采用Annexin-V/PI染色定量考察小檗碱对肿瘤细胞凋亡的影响,运用Western Blot实验检测肿瘤相关通路蛋白表达来进行研究。实验表明小檗碱对乳腺癌MDA-MB-231细胞增殖具有抑制作用,使细胞中自噬因子Beclin 1表达增加,诱导细胞自噬泡的形成,导致肿瘤细胞发生凋亡。综上说明小檗碱是通过抑制AKT-mTOR通路,诱导MDA-MB-231细胞的自噬以及凋亡,从而发挥抗肿瘤作用。     

小檗碱的研究进展

小檗碱是从黄连和小檗碱属类等植物中提取分离得到的一种异喹啉类生物碱。在中国传统药方中,这些中药已广泛用于湿热症。许多治疗风湿性疾病的药方的重要成分皆是小檗碱属类的提取物。作为这些提取物中的主要活性成分,小檗碱被证实在治疗自身免疫性疾病、糖尿病、肿瘤、腹泻等方面可发挥重要作用。由于小檗碱生物学作用广泛,其潜在的应用价值巨大。为了认识这种重要中药成分的具体潜能,我们需要更多的动物和人类实验研究。     

小檗碱对2型糖尿病中国地鼠肝脏葡萄糖激酶、葡萄糖-6-磷酸酶和磷酸烯醇式丙酮酸羧激酶mRNA表达的影响

目的研究小檗碱对2型糖尿病中国地鼠肝脏葡萄糖激酶（GcK）、葡萄糖-6-磷酸酶（G6P）和磷酸烯醇式丙酮酸羧激酶（PEPCK）mRNA表达的影响,探讨小檗碱影响糖代谢的分子机制。方法以高脂高热量饲料喂养结合腹腔注射小剂量链脲佐菌素（STZ）的方法制作2型糖尿病中国地鼠模型,成模后随机分成模型组、小檗碱组、二甲双胍组,各药干预9周。同时设立对照组。观察小檗碱疗效及对肝脏GcK、G6P、PEPCK mRNA表达的影响。结果与模型组相比,小檗碱增强胰岛素敏感性,降低血糖血脂,增高肝脏GcK的mRNA表达,降低肝脏G6P、PEPCK mRNA的表达。结论小檗碱降低2型糖尿病血糖的作用机制可能与提高肝脏GcK mRNA的表达和降低G6P、PEPCK mRNA的表达有关。     

小檗碱通过JNK通路调控柯萨奇病毒B3感染心肌细胞凋亡的作用

小檗碱是具有细胞保护作用的生物碱,能够在柯萨奇病毒B3(CVB3)感染引起的病毒性心肌炎小鼠中发挥心肌保护作用,但具体的机制未阐明。在内皮细胞中,小檗碱通过c-Jun氨基末端激酶(JNK)通路抑制细胞凋亡,因此本研究将分析小檗碱通过JNK通路调控CVB3感染心肌细胞凋亡的作用。H9c2心肌细胞分为对照组(不含药物的DMEM处理)、模型组(含CVB3的DMEM处理)、小檗碱组(含CVB3及小檗碱的DMEM处理)、小檗碱+JNK质粒组(含CVB3、小檗碱、JNK质粒的DMEM处理),检测细胞凋亡率、肿瘤坏死因子-α(TNF-α)、白介素-6(IL-6)、活性氧(ROS)、丙二醛(MDA)的含量、p-JNK、cleaved caspase-3、bax、bcl-2的表达量。结果显示,模型组的细胞凋亡率、TNF-α、IL-6、ROS、MDA的含量、p-JNK、cleaved caspase-3、bax的表达量高于对照组,bcl-2的表达量低于对照组(P<0.05);小檗碱组的细胞凋亡率、TNF-α、IL-6、ROS、MDA的含量、p-JNK、cleaved caspase-3、bax的表达量低于模型组,bcl-2的表达量高于模型组(P<0.05);小檗碱+JNK质粒组的细胞凋亡率、TNF-α、IL-6、ROS、MDA的含量、p-JNK、cleaved caspase-3、bax的表达量高于小檗碱组,bcl-2的表达量低于小檗碱组(P<0.05)。以上结果表明小檗碱对CVB3感染心肌细胞的凋亡具有抑制作用,抑制JNK通路是介导这一作用可能的分子机制。     

抗炎药物用于 2 型糖尿病预防与治疗的研究进展

近年来,炎症反应在2型糖尿病发病机制中的作用受到广泛关注。流行病学和实验动物研究均证明,肥胖及其诱发的慢性炎症 与2型糖尿病有密切的关系。基于诸多临床流行病学调查及大型前瞻性研究结果,目前已形成对糖尿病胰岛素耐受性的炎症发病机制的 共识。到目前为止,多种具有抗炎作用机制的活性小分子药物已经上市或进入临床研究阶段,这些药物单独治疗或与传统降糖药物联用 均取得了令人满意的效果,显示了糖尿病抗炎治疗的前景。主要综述近年来慢性炎症在2型糖尿病发生发展过程中的分子机制以及抗炎 药物用于治疗2型糖尿病的研究进展     

小檗碱的抗菌作用研究进展

小檗碱在临床上广泛运用于抗痢治疗,其抗菌作用被认为是其发挥抗痢作用的主要药理学机制.小檗碱的体内外抗茵活性明显,其抗茵机制可能涉及对多种酶蛋白活性抑制,肠毒素拮抗作用和抗粘附作用等机制.小檗碱的直接抗茵作用可能与其非特异性蛋白抑制作用有关.     

天然黄酮类化合物治疗2型糖尿病的机制研究进展

2型糖尿病(T2DM)是一种以胰岛素抵抗或胰岛β细胞分泌功能缺陷为特征的代谢性疾病。黄酮类化合物在预防和治疗2型糖尿病中发挥着重要作用,其作用靶点多、机制复杂,尚难完全阐明。因此,明确黄酮类单体化合物的作用机制十分重要。黄酮类化合物可作用于胰腺β细胞、肝细胞、脂肪细胞和骨骼肌细胞中的多个靶点和不同的信号通路。本文分类综述了近年来天然黄酮类化合物抗2型糖尿病作用及机制的研究进展。     

Modulation of adipose tissue inflammation by bioactive food compounds

Adipose tissue has an important endocrine function in the regulation of whole-body metabolism. Obesity leads to a chronic low-grade inflammation of the adipose tissue, which disrupts this endocrine function and results in metabolic derangements, such as type-2 diabetes. Dietary bioactive compounds, such as polyphenols and certain fatty acids, are known to suppress both systemic and adipose tissue inflammation and have the potential to improve these obesity-associated metabolic disorders. Mechanistically, polyphenolic compounds including non-flavonoids, such as curcumin and resveratrol, and flavonoids, such as catechins (tea-polyphenols), quercetin and isoflavones, suppress nuclear factor-κB (NF-κB) and mitogen-activated protein (MAP) kinases (MAPK) pathways while activating the 5′ adenosine monophosphate-activated protein kinase (AMPK) pathway in adipose tissue. Dietary polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), conjugated linoleic acid (CLA) and monounsaturated fatty acids (MUFA), such as oleic acid, also impart anti-inflammatory effects through several mechanisms. These include activation of AMPK and peroxisome proliferator-activated receptor gamma (PPAR-γ), as well as suppression of toll-like receptors (TLRs) and NF-κB pathway. This review discusses the major molecular mechanisms of dietary polyphenols and fatty acids, alone or in combination, which are responsible for adipose tissue-associated anti-inflammatory effects.     

Alpha-lipoic acid mitigates insulin resistance in Goto-Kakizaki rats.

Impaired glucose uptake and metabolism by peripheral tissues is a common feature in both type I and type II diabetes mellitus. This phenomenon was examined in the context of oxidative stress and the early events within the insulin signalling pathway using soleus muscles derived from non-obese, insulin-resistant type II diabetic Goto-Kakizaki (GK) rats, a well-known genetic rat model for human type II diabetes. Insulin-stimulated glucose transport was impaired in soleus muscle from GK rats. Oxidative and non-oxidative glucose disposal pathways represented by glucose oxidation and glycogen synthesis in soleus muscles of GK rats appear to be resistant to the action of insulin when compared to their corresponding control values. These diabetes-related abnormalities in glucose disposal were associated with a marked diminution in the insulin-mediated enhancement of protein kinase B (Akt/PKB) and insulin receptor substrate-1 (IRS-1)-associated phosphatidylinostol 3-kinase (PI 3-kinase) activities; these two kinases are key elements in the insulin signalling pathway. Moreover, heightened state of oxidative stress, as indicated by protein bound carbonyl content, was evident in soleus muscle of GK diabetic rats. Chronic administration of the hydrophobic/hydrophilic antioxidant alpha -lipoic-acid (ALA, 100 mg/kg, i.p.) partly ameliorated the diabetes-related deficit in glucose metabolism, protein oxidation as well as the activation by insulin of the various steps of the insulin signalling pathway, including the enzymes Akt/PKB and PI-3 kinase. Overall, the current investigation illuminates the concept that oxidative stress may indeed be involved in the pathogenesis of certain types of insulin resistance. It also harmonizes with the notion of including potent antioxidants such as ALA in the armamentarium of antidiabetic therapy.     

Benfotiamine Attenuates Inflammatory Response in LPS Stimulated BV-2 Microglia

Microglial cells are resident immune cells of the central nervous system (CNS), recognized as key elements in the regulation of neural homeostasis and the response to injury and repair. As excessive activation of microglia may lead to neurodegeneration, therapeutic strategies targeting its inhibition were shown to improve treatment of most neurodegenerative diseases. Benfotiamine is a synthetic vitamin B1 (thiamine) derivate exerting potentially anti-inflammatory effects. Despite the encouraging results regarding benfotiamine potential to alleviate diabetic microangiopathy, neuropathy and other oxidative stress-induced pathological conditions, its activities and cellular mechanisms during microglial activation have yet to be elucidated. In the present study, the anti-inflammatory effects of benfotiamine were investigated in lipopolysaccharide (LPS)-stimulated murine BV-2 microglia. We determined that benfotiamine remodels activated microglia to acquire the shape that is characteristic of non-stimulated BV-2 cells. In addition, benfotiamine significantly decreased production of pro-inflammatory mediators such as inducible form of nitric oxide synthase (iNOS) and NO; cyclooxygenase-2 (COX-2), heat-shock protein 70 (Hsp70), tumor necrosis factor alpha α (TNF-α), interleukin-6 (IL-6), whereas it increased anti-inflammatory interleukin-10 (IL-10) production in LPS stimulated BV-2 microglia. Moreover, benfotiamine suppressed the phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2), c-Jun N-terminal kinases (JNK) and protein kinase B Akt/PKB. Treatment with specific inhibitors revealed that benfotiamine-mediated suppression of NO production was via JNK1/2 and Akt pathway, while the cytokine suppression includes ERK1/2, JNK1/2 and Akt pathways. Finally, the potentially protective effect is mediated by the suppression of translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in the nucleus. Therefore, benfotiamine may have therapeutic potential for neurodegenerative diseases by inhibiting inflammatory mediators and enhancing anti-inflammatory factor production in activated microglia.     

Age-related differences in MAP kinase activity in VSMC in response to glucose or TNF-alpha

Aortic vascular smooth muscle cells (VSMC) were used to study the effect of age on responses to high glucose concentrations or the cytokine, tumor necrosis factor-alpha (TNF-alpha). Activator protein-1 (AP-1) binding to DNA increased more in VSMC from old versus young rats (P < 0.02) and was related to increased expression of its components, c-Fos, Fra-1, and JunD. The relationship to upstream signals, i.e., activities of mitogen-activated protein kinases (MAPK), was studied using antibodies to total and phosphorylated forms of extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK) and p38. High glucose and TNF-alpha increased ERK phosphorylation more in old (P < 0.05); whereas only TNF-alpha induced JNK activation in young (P < 0.04). PD98059, a MEK inhibitor, attenuated AP-1 activation, lowered c-Fos and Fra-1 protein levels and reduced cell number and cells positive for proliferating cell nuclear antigen in old. We concluded that age differentially influenced activation of signaling pathways in VSMC exposed to high glucose or TNF-alpha. This may contribute to the increased risk for vascular disease associated with aging and diabetes mellitus (DM).     

Hydrolyzed camel whey protein alleviated heat stress-induced hepatocyte damage by activated Nrf2/HO-1 signaling pathway and inhibited NF-κB/NLRP3 axis

Liver damage is the most severe complication of heat stress (HS). Hydrolyzed camel whey protein (CWP) possesses bioactive peptides with obviously antioxidant and anti-inflammatory activities. The current study aims to investigate whether CWP that is hydrolyzed by a simulated gastrointestinal digestion process, named S-CWP, protects BRL-3A hepatocytes from HS-induced damage via antioxidant and anti-inflammatory mechanisms. BRL-3A cells were pretreated with S-CWP before being treated at 43 °C for 1 h, and the levels of the cellular oxidative stress, inflammation, apoptosis, biomarkers for liver function, the activities of several antioxidant enzymes, and the cell viability were analyzed. The expression level of pivotal proteins in correlative signaling pathways was evaluated by western blotting. We confirmed that S-CWP alleviated HS-induced hepatocytes oxidative stress by decreased reactive oxygen species (ROS), nitric oxide (NO), 8-Hydroxy-2′-deoxyguanosine (8-OHdG), lipid peroxidation (LPO), protein carbonylation (PCO), and the activities of NADPH oxidase while enhanced superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), heme oxygenase-1 (HO-1) activities, and GSH content. S-CWP suppressed HS-induced inflammatory response by reducing the phosphorylation of NF-κB p65, the expression of NLRP3, and caspase-1 and finally alleviated caspase-3-mediated apoptosis. S-CWP also alleviated HS-induced hepatocyte injury by reducing alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) levels and restoring Heat Shock Protein 70 (HSP70) expression. Furthermore, S-CWP treatment significantly enhanced the expression of NF-E2-related nuclear factor erythroid-2 (Nrf2) and HO-1. The antioxidant and anti-inflammatory effects of S-CWP were weakened by ML385, a specific Nrf2 inhibitor. Additionally, zinc protoporphyrin (ZnPP), a specific HO-1 inhibitor, significantly reversed S-CWP-induced reduction in the phosphorylation of NF-κB p65. Thus, our results revealed that S-CWP protected against HS-induced hepatocytes damage via activating the Nrf2/HO-1 signaling pathway and inhibiting NF-κB/NLRP3 axis.     

Anti-inflammatory effects of resolvins in diabetic nephropathy: Mechanistic pathways

The incidence of diabetes mellitus is growing rapidly. The exact pathophysiology of diabetes is unclear, but there is increasing evidence of the role of the inflammatory response in both developing diabetes as well as its complications. Resolvins are naturally occurring polyunsaturated fatty acids that are found in fish oil and sea food that have been shown to possess anti-inflammatory actions in several tissues including the kidneys. The pathways by which resolvins exert this anti-inflammatory effect are unclear. In this review we discuss the evidence showing that resolvins can suppress inflammatory responses via at least five molecular mechanisms through inhibition of the nucleotide-binding oligomerization domain protein 3 inflammasome, inhibition of nuclear factor κB molecular pathways, improvement of oxidative stress, modulation of nitric oxide synthesis/release and prevention of local and systemic leukocytosis. Complete understanding of these molecular pathways is important as this may lead to the development of new effective therapeutic strategies for diabetes and diabetic nephropathy.     

Eriodictyol inhibits high glucose-induced oxidative stress and inflammation in retinal ganglial cells

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes mellitus and is considered as a leading cause of blindness. Oxidative stress and inflammation are significant drivers for the development of DR. Eriodictyol, a flavonoid compound, was proved to possess anti-inflammatory, antioxidative, and antidiabetic activities. However, the role of eriodictyol in DR has not been unveiled. In the current study, we explored the protective effects of eriodictyol on high glucose (HG)-induced rat retinal ganglial cells (RGCs). The results suggested that eriodictyol improved cell viability of HG-induced rat RGC-5 cells in a dose-dependent manner. Eriodictyol reduced the reactive oxygen species production and increased the activities of superoxide dismutase, glutathione peroxidase and catalase in rat RGC-5 cells in response to HG stimulation. The production of proinflammatory cytokines including tumor necrosis factor alpha and interleukin-8 was diminished after eriodictyol treatment. Eriodictyol also suppressed cell apoptosis induced HG in rat RGC-5 cells. Furthermore, eriodictyol enhanced the nuclear translocation of nuclear factor erythroid-2 (E2)-related factor 2 (Nrf2) and elevated the expression of antioxidant enzyme heme-oxygenase-1 (HO-1). These findings suggested that eriodictyol protects the RGC-5 cells from HG-induced oxidative stress, inflammation, and cell apoptosis through regulating the activation of Nrf2/HO-1 pathway.     

Therapeutic and biological activities of berberine: The involvement of Nrf2 signaling pathway

Since the beginning of the 21st century, studies have focused on developing drugs from naturally occurring compounds. Berberine (Brb) as a plant-derived compound is of interest. It is an isoquinone alkaloid which is derived from Berberis aristata, Berberis aquifolium and Berberis vulgaris. This plant-derived compound has a variety of pharmacological effects such as antioxidant, anti-inflammatory, antidiabetic, antidiarrheal, antitumor, antimicrobial, and anti-inflammatory. Various studies have demonstrated the therapeutic and biological activities of Brb, but there is a lack of a precise review to manifest the signaling pathway of action of Brb. The nuclear factor erythroid 2-related factor 2 (Nrf2) is a highly conserved pathway which mainly involves in preservation of redox balance. At the present review, we describe the therapeutic and biological activities of Brb as well as the relevant mechanisms specially focused on the Nrf2 signaling pathway.     

Research update on the association between SFRP5, an anti-inflammatory adipokine,with obesity,type 2 diabetes mellitus and coronary heart disease

Secreted frizzled-related protein 5 (SFRP5), an anti-inflammatory adipokine secreted by adipocytes, has been demonstrated to exert its anti-inflammatory effect via antagonizing the non-canonical wingless-type family member 5A (WNT5A) signalling pathways. The WNT5A protein, as a potent pro-inflammatory signalling molecule, is strongly involved in a variety of inflammatory disorders such as obesity, type 2 diabetes mellitus (T2DM) and atherosclerosis. In this review, we systematically outlined the current understanding on the roles of SFRP5 in the pathogenesis of three inflammatory diseases including obesity, T2DM and coronary heart disease (CHD). Our review might stimulate future research using SFRP5 as a promising novel therapeutic target for the treatment of obesity, T2DM and CHD.