KLF4在LPS诱导的心肌细胞损伤中的作用研究

背景:KLF4作为一种转录因子在保持血管内皮功能中发挥重要作用,然而其是否能够保护心肌细胞免受脂多糖诱导的损伤尚不清楚。目的探讨KLF4在脂多糖诱导的心肌细胞损伤中的作用。方法:分离培养原代大鼠乳鼠心肌细胞,将其随机（随机数字法）分为5组：空白组,阴性对照组（NC组）,NC+脂多糖刺激组（NC+LPS组）,KLF4过表达组,KLF4过表达+LPS组。采用MTT法检测细胞活性,采用试剂盒检测细胞活性氧（ROS）,超氧化物歧化酶（SOD2）,谷胱甘肽过氧化物酶（Gpx）和丙二醛（MDA）的水平;采用酶联免疫吸附法（Elisa）检测细胞中肿瘤坏死因子（TNFa）,白细胞介素-1β（IL-1β）和IL-6的水平。采用Tunel染色检测细胞凋亡。采用免疫印迹检测TLR4和核因子E2相关因子2（NRF2）的蛋白水平。结果:心肌细胞转染KLF4过表达腺病毒后,细胞中KLF4的表达明显高于NC组（ P<0.05）。NC+LPS组细胞活性明显低于NC组（ P<0.05）,KLF4过表达+LPS组细胞活性高于NC+LPS组（ P<0.05）。与对照组相比,NC+LPS组中的心肌细胞TNFα、IL-1β、IL-6蛋白表达水平明显升高（ P<0.0001）,KLF4过表达+LPS组心肌细胞TNFα、IL-1β、IL-6蛋白表达水平则显著降低（ P<0.0001）。NC+LPS组心肌细胞ROS和MDA水平明显高于NC组,而SOD2和Gpx的活性低于NC组（ P<0.0001）;KLF4过表达+LPS组心肌细胞ROS和MDA水平的水平明显降低,而SOD2和Gpx的活性明显升高（ P<0.0001）。LPS组心肌细胞凋亡数量明显高于NC组,KLF4过表达+LPS组心肌细胞凋亡数量明显降低（ P<0.001）。LPS组心肌细胞TLR4总蛋白水平高于NC组,NRF2的核蛋白水平低于NC组;KLF4过表达+LPS组心肌细胞TLR4的总蛋白水平降低,NRF2的核蛋白水平显著增高（ P<0.001）。 结论：:KLF4可抑制LPS诱导的心肌细胞损伤,其作用机制可能是通过抑制LPS诱导的心肌细胞中TLR4的表达,促进NRF2向细胞核转移来抑制炎症因子释放,减轻氧化应激损伤及抑制细胞凋亡。     

五味子乙素对脂多糖诱导的脓毒症急性肺损伤大鼠肺组织病理损伤、炎症反应和核因子-κB表达的影响

目的 观察五味子乙素对脂多糖（lipopolysaccharide,LPS）诱导的脓毒症急性肺损伤大鼠肺组织病理损伤、炎症反应和核因子 -κB （nuclear factor kappa-B,NF-κB）表达的影响。方法 采用气管滴注40 mg/kg LPS制备大鼠急性肺损伤大鼠模型,手术前1 h腹腔注射80 mg/kg 五味子乙素进行干预治疗,测定大鼠肺湿/干质量比,BCA试剂盒测定大鼠支气管肺泡灌洗液（bronchoalceolar lavage fluid,BALF）总蛋白,牛鲍氏计数板计算 BALF中白细胞数,苏木精-伊红染色观察大鼠肺组织损伤情况,ELISA法检测大鼠肺组织中肿瘤坏死因子-α（tumor necrosis factor-α,TNF-α）、白细胞介素-1β（interleukin-1β,IL-1β）、白细胞介素-6（interleukin-6,IL-6）含量,相关试剂盒检测大鼠肺组织中丙二醛（malondialdehyde,MDA）和超氧化物歧化酶（superoxide dismutase,SOD）含量,蛋白质印迹法检测大鼠肺组织中NF-κB p65、磷酸核因子- κB 抑制蛋白（phosphorylation inhibitor of nuclear factor kappa-B,pIκBα）和Toll样受体4（Toll-like receptor 4,TLR4）的表达水平。结果 与模型组相比,五味子乙素组大鼠肺湿/干质量比、BALF中总蛋白含量及白细胞数均显著减少（P<0.05）,病理损伤显著减轻,TNF-α、IL-1β、IL-6含量均显著减少（P<0.05）,MDA含量显著下降,SOD活性显著升高（P<0.05）,NF-κB p65、pIκBα和TLR4表达水平均显著下调（P<0.05）。结论 五味子乙素能够减轻LPS诱导的脓毒症急性肺损伤大鼠肺组织的病理损伤,抑制炎症反应和氧化应激反应,抑制NF-κB通路激活。     

The protective effects of coumestrol against amyloid-beta peptide- and lipopolysaccharide-induced toxicity on mice astrocytes

Abstract

Objectives: Estrogen replacement therapy can decrease the risk of developing Alzheimer’s disease. Phytoestrogens have been proposed as potential alternatives to estrogen replacement therapy. The purpose of this study was to evaluate the in vitro protective effects of coumestrol on mice astrocytes.

Methods: Different concentrations of coumestrol were tested for their protective efficacy against two toxic insults, lipopolysaccharide (LPS) and amyloid-beta peptide, on astrocytes. The mitochondrial activity of astrocytes was determined, and the protective efficacy and pathway were examined by their specific gene expression and protein change.

Results: The results showed that coumestrol induced a modest but significant increase in viability of astrocytes, while the viability of astrocytes was reduced following exposure to LPS and amyloid-beta peptide. The addition of coumestrol could reverse the toxic effect induced by LPS and amyloid-beta peptide. Both the LPS and amyloid-beta peptide enhanced interleukin 1, interleukin 6, and tumor necrosis factor-alpha synthesis and these effects were inhibited by 10^?9M coumestrol. This effect was more obvious on the LPS-induced inflammation. The estrogen receptor expression was upregulated by coumestrol, while the effect was more obvious on estrogen receptor-beta (ER-beta). These effects can be inhibited by extracellular signal-regulated kinase and c-Jun N-terminal kinase inhibitors but not p38 inhibitor.

Discussion: The current data support a possible role for astrocytes in the mediation of neuroprotection by coumestrol. An indirect extracellular signal-regulated kinase/c-Jun N-terminal kinase signaling pathway to downregulate the expression of interleukin 1, interleukin 6, and the tumor necrosis factor-alpha cytotoxic effect may act in concert with the proposed direct ER-beta biosynethsis pathway to achieve a widespread, global protection of ER-beta positive neurons.     

髓样分化因子88在妊娠期糖尿病发病机制中的作用研究

目的:通过调控孕妇单核细胞中髓样分化因子88(My D88)的表达水平,研究My D88在妊娠期糖尿病(GDM)发病机制中的作用。方法:30例正常妊娠孕妇为正常组,30例GDM患者为GDM组,两组每个样本处理均相同,每个样本各分为4个组,分别为未处理组、LPS组、ST2825组、LPS+ST2825组。采用Western blot法检测并比较各组单核细胞中My D88及核转录因子-κB(NF-κB)/p65的表达量,分析各组中My D88与NF-κB/p65的相关性;采用ELISA法检测并比较各组培养液中肿瘤坏死因子-α(TNF-α)、白介素-1(IL-1)、白介素-10(IL-10)水平。结果:①正常组和GDM组组内的比较:LPS组、ST2825组的My D88及NF-κB/p65的表达水平与同组未处理组相比,差异有统计学意义(P0.05);LPS+ST2825组的My D88及NF-κB/p65的表达水平明显低于同组的LPS组(P0.05)。正常组与GDM组组间比较:GDM组各处理组My D88及NF-κB/p65的表达水平均较正常组相同处理组明显升高(P0.05)。②两组中除未处理组外,其他处理组的My D88与NF-κB/p65的表达水平均呈正相关关系(P0.05)。③GDM组中未处理组和LPS组中的细胞因子(TNF-α、IL-1、IL-10)的表达水平均高于正常组中未处理组及LPS组(P0.05);GDM组中LPS组3个细胞因子的表达水平高于其未处理组(P0.05),ST2825组3个细胞因子的表达水平低于其未处理组(P0.05)。GDM组中LPS+ST2825组3个细胞因子的表达水平低于其LPS组(P0.05)。结论:调控GDM孕妇单核细胞中上游My D88的表达水平,下游NF-κB/p65及细胞因子(TNF-α、IL-1、IL-10)水平发生相应变化,提示My D88可能参与了GDM的发生并在其发病机制中起着重要作用。     

c-Src激酶对脂多糖致炎过程中occludin蛋白表达的影响

目的 探讨在脂多糖(lipopolysaccharide,LPS)处理小鼠肺泡上皮细胞(mouse lung epithelial-12,MLE-12)过程中,c-Src激酶对occhdin蛋白表达的影响. 方法 将培养的MLE-12细胞按随机数字表法分3组(每组3孔细胞):对照组(C组)、LPS实验组(L组)、LPS+c-Src激酶抑制剂PP2组(L+P组).C组不做任何处理;L组用LPS(浓度为10 mg/L)处理,处理时间为1、3、6 h;L+P组用PP2(浓度为100 μmol/L)预处理60 min,然后LPS(浓度为10 mg/L)处理6h.Western blot法和免疫荧光染色法分别检测各组不同时间点occludin蛋白的表达. 结果 Western blot发现,与C组比较:L组中6h时点occludin蛋白表达下调明显、c-Src表达明显升高,差异均有统计学意义(P＜0.05);与L组6h比较,L+P组occludin蛋白表达上调(P＜0.05).免疫荧光染色显示,occludin蛋白主要表达于细胞膜上,LPS影响occludin蛋白在膜上分布,PP2可以减轻LPS的影响. 结论 LPS导致MLE-12细胞紧密连接蛋白occludin表达下调,c-Src激酶参与其调节.     

Alterations of Thymic Epithelial Cells in Lipopolysaccharide-induced Neonatal Thymus Involution

Background:

Vascular endothelial growth factor (VEGF) in the thymus was mainly produced by the thymic epithelial cells (TECs), the predominant component of the thymic microenvironment. The progression of TECs and the roles of VEGF in the neonatal thymus during sepsis have not been reported. This study aimed to explore the alterations of TECs and VEGF level in the neonatal thymus involution and to explore the possible mechanisms at the cellular level.

Methods:

By establishing a model of clinical sepsis, the changes of TECs were measured by hematoxylin-eosin staining, confocal microscopy, and flow cytometry. Moreover, the levels of VEGF in serum and thymus were assessed based on enzyme-linked immunosorbent assay and Western blotting.

Results:

The number of thymocytes and TECs was significantly decreased 24 h after lipopolysaccharide (LPS) challenge, (2.40 ± 0.46)×10⁷ vs. (3.93 ± 0.66)×10⁷ and (1.16 ± 0.14)×10⁵ vs. (2.20 ± 0.19)×10⁵, P < 0.05, respectively. Cortical TECs and medullary TECs in the LPS-treated mice were decreased 1.5-fold and 3.9-fold, P < 0.05, respectively, lower than those in the controls. The number of thymic epithelial progenitors was also decreased. VEGF expression in TECs was down-regulated in a time-dependent manner.

Conclusion:

VEGF in thymic cells subsets might contribute to the development of TECs in neonatal sepsis.     

LPS-pretreatment adipose-derived mesenchymal stromal cells promote wound healing in diabetic rats by improving angiogenesis

Mesenchymal stem cells (MSCs) play a key role in wound healing, and the advantages of pretreated MSCs in wound healing have previously been reported. In the present study, we investigated the impact of LPS pretreated human adipose-derived MSCs on skin wound healing in diabetic rats. We found that some improvements occurred through improving angiogenesis. Then, we scrutinized the impact of lipopolysaccharide (LPS) treatment on human adipose-derived MSCs in a high-glucose (HG) medium, as an in vitro diabetic model. In vivo findings revealed significant improvements in epithelialization and angiogenesis of diabetic wounds which received LPS pre-MSCs. Particularly, LPS pre-MSCs-treated diabetic wounds reached considerably higher percentages of wound closure. Also, the granulation tissue of these wounds had higher pronounced epithelialization and more vascularization compared with PBS-treated and MSCs-treated diabetic ones by CD31, VEGF, CD90, collagen 1, and collagen 3 immunostaining. Western-blots analyses indicated that LPS pre-MSCs led to the upregulation of vascular endothelial growth factor (VEGF) and DNMT1. In addition, significantly higher cell viability (proliferation/colonie), and elevated VEGF and DNMT1 protein expression were observed when MSCs were treated with LPS (10 ng/ml, 6 h) in HG culture media. Based on these findings, it is suggested that LPS pre-MSCs could promote wound repair and skin regeneration, in some major processes, via the improvement of cellular behaviors of MSCs in the diabetic microenvironment. The beneficial advantages of LPS treated with mesenchymal stem cells on wound healing may lead to establishing a novel approach as an alternative therapeutic procedure to cure chronic wounds in diabetic conditions.