Porphyromonas gingivalis Lipopolysaccharide Upregulates Insulin Secretion From Pancreatic β Cell Line MIN6

Background: A close association between periodontitis and diabetes has been demonstrated in human cross‐sectional studies, but an exact relationship between periodontitis and prediabetes has not been established. Previous studies using animal model systems consistently have shown that hyperinsulinemia occurs in animals with periodontitis compared to animals with healthy periodontium (while maintaining normoglycemia). Because bacterial lipopolysaccharide (LPS) plays an important role in the pathogenesis of periodontitis, we hypothesized that LPS may stimulate insulin secretion through a direct effect on β cell function. To test this hypothesis, pancreatic β cell line MIN6 cells were used to determine the effect of Porphyromonas gingivalis (Pg) LPS on insulin secretion. Furthermore, expression of genes altered by Pg LPS in innate immunity and insulin‐signaling pathways was determined. Methods: MIN6 cells were grown in medium with glucose concentration of normoglycemia (5.5 mM). Pg LPS was added to each well at final concentrations of 50, 200, and 500 ng/mL. Insulin secretion was measured using enzyme‐linked immunosorbent assay. Gene expression levels altered by Pg LPS were determined by polymerase chain reaction (PCR) array for mouse innate and adaptive immunity response and mouse insulin‐signaling pathways, and results were confirmed for specific genes of interest by quantitative PCR. Results: Pg LPS stimulated insulin secretion in the normoglycemic condition by ≈1.5‐ to 3.0‐fold depending on the concentration of LPS. Pg LPS treatment altered the expression of several genes involved in innate and adaptive immune response and insulin‐signaling pathway. Pg LPS upregulated the expression of the immune response–related genes cluster of differentiation 8a (Cd8a), Cd14, and intercellular adhesion molecule‐1 (Icam1) by about two‐fold. LPS also increased the expression of two insulin signaling–related genes, glucose‐6‐phosphatase catalytic subunit (G6pc) and insulin‐like 3 (Insl3), by three‐ to four‐fold. Conclusions: We have demonstrated for the first time that Pg LPS stimulates insulin secretion by pancreatic β cell line MIN cells. Pg LPS may have significant implications on the development of β cell compensation and insulin resistance in prediabetes in individuals with periodontitis.     

咯利普兰对脂多糖诱导的小鼠急性肺损伤的抑制作用

目的探讨磷酸二酯酶4(PDE4)抑制剂治疗急性肺损伤的作用机制。方法气道内滴入脂多糖3 mg.kg-1制备小鼠急性肺损伤模型,10 min后一次性ip不同剂量咯利普兰或地塞米松;同时设假手术和模型组。给药6 h后处死小鼠,观察肺湿重/干重比值和肺组织的病理改变;用细胞形态学方法计数支气管肺泡灌洗液(BALF)中白细胞和中性粒细胞;考马斯亮蓝法测定BALF总蛋白含量;髓过氧化物酶(MPO)活性测定试剂盒测定肺组织匀浆MPO活性;ELISA法测定肺组织匀浆肿瘤坏死因子α(TNF-α)含量;高效液相色谱法测定肺组织匀浆中cAMP-PDE和PDE4活性。结果小鼠气道内滴入脂多糖6 h后,与假手术组比较,模型组肺湿重/干重比值明显升高;肺组织病理观察可见肺血管和气道周围有大量中性粒细胞浸润;BALF中白细胞和中性粒细胞增多,蛋白含量增加;肺组织MPO活性、TNF-α水平、cAMP-PDE和PDE4活性升高。与模型组比较,咯利普兰(0.1,0.3及1.0 mg.kg-1)和地塞米松(0.5 mg.kg-1)可降低肺组织湿重/干重比值,降低BALF中白细胞总数、中性粒细胞数目和蛋白含量,改善肺组织病理变化,肺组织中MPO活性、TNF-α含量、cAMP-PDE和PDE4活性亦明显降低。结论咯利普兰治疗急性肺损伤的作用机制可能与抑制PDE4活性、抑制中性粒细胞黏附和趋化及降低TNF-α水平有关。     

Cholecystokinin octapeptide inhibits the in vitro expression of CD14 in rat pulmonary interstitial macrophages induced by lipopolysaccharide

Obejective To study the effect of cholecystokinin octapeptide (CCK-8) on lipopolysaccharide (LPS)-stimulated pulmonary interstitial macrophages （PIM） in vitroMethods PIM were isolated and cultured in the presence or absence of LPS, CCK-8, proglumide (the antagonist of CCK receptors) and vehicle. The expression of membrane CD14 (mCD14) protein was assayed by flow cytometry and soluble CD14 (sCD14) in the supernatant was analyzed semi-quantitatively by Western blot. TNF-α in the supernatant was detected with ELISA.Results CCK-8, at concentrations of 10［-7］ mol/L and 10［-6］ mol/L, significantly inhibited the expression of mCD14. Release of sCD14 and TNF-α in the supernatant was up-regulated by LPS (1μg/ml) but reduced by CCK-8. The effect of CCK-8 was inhibited by proglumide.Conclusion CCK-8 negatively modulated several functions of LPS-stimulated PIM through CCK receptors. This may be one of the mechanisms for CCK-8 to alleviate inflammation in lung tissue during endotoxemia.     

三氯化钆减轻肝缺血再灌注对内毒素的敏感性的实验研究

目的探讨三氯化钆(Gdcl3)对肝缺血再灌注后腹腔注射内毒素(LPS)的影响。方法雄性Wistar大鼠随机分为4组:Ⅰ对照(control)组,只开腹和关腹,不做其他任何处理;Ⅱ对照 LPS(Con LPS)组,开腹后1 h腹腔注射LPS(200μg/kg)1 h;Ⅲ缺血再灌注 LPS(I/R LPS)组,术前24,48 h经鼠尾静脉注射等量0.9%氯化钠(pH 3.5);Ⅳ氯化钆 缺血再灌注 LPS(GdCl3 I/R LPS)组:术前24,48 h经鼠尾静脉注射0.5%氯化钆溶液(10 mg/kg)。第3天进行肝脏部分缺血再灌注手术(阻断约70%肝血流)。缺血45 min后,再灌注1 h腹腔注射LPS(200μg/kg)1 h乙醚麻醉后,开腹进行无菌无热源腹主动脉采血,肝左叶用10%甲醛溶液固定,肝中叶及脾脏分别包裹后置-70℃冰箱保存,制备匀浆用于丙二醛、谷胱甘肽、TNF-α含量的测定。结果缺血45 min后,再灌注1 h腹腔注射LPS(200μg/kg)1 h,GdCl3 I/R LPS组血浆谷丙转氨酶活性、肝脏丙二醛及TNF-α含量均显著低于I/R LPS组(P<0.001),而谷胱甘肽含量则明显高于肝损伤组(P<0.05)。结论三氯化钆减轻肝缺血再灌注对内毒素的敏感性。     

油茶皂苷对脂多糖诱导人脐静脉内皮细胞ICAM-1表达的抑制作用

 目的观察油茶皂苷(SQS)对脂多糖(LPS)诱导人脐静脉内皮细胞(HUVECs)ICAM-1表达的作用并探讨其作用机制。方法建立HUVECs LPS应激模型,以油茶皂苷(10.0,1.0,0.1μmol·L^-1)和ERK1/2抑制剂PD98059(10.0μg·L^-1)预处理细胞8h,取培养细胞上清液测定LDH活性,HUVECs分别用于测定细胞存活率及ICAM-1 mRNA和蛋白的表达。结果LPS可显著升高LDH活性,上调ICAM-1 mRNA和蛋白的表达(P<0.01)。SQS呈浓度依赖性地对抗上述改变,其作用与PD98059的作用相似。结论SQS可抑制LPS诱导的HUVECs ICAM-1表达的上调,其机制可能与MAPK-ERK1/2(MEK1/2)信号转导通路有关。     

Effect of low dose Actinobacillus actinomycetemcomitans lipopolysaccharide pretreatment on cytokine production by human whole blood

BACKGROUND AND OBJECTIVE: Periodontal disease is known to influence the systemic condition in various ways, and the bacteria and their products, such as lipopolysaccharides (LPS), may spread from periodontal lesions via the systemic circulation to affect distant organs. The level of LPS in plasma from such patients is reported to be very low, and this low level of LPS is suspected to have priming or desensitizing effect. Thus, we investigated the effects of low dose LPS pretreatment on LPS-dependent cytokine production by whole blood cells ex vivo. METHODS: Blood samples obtained from seven systemically and periodontally healthy individuals were pretreated with or without 5 pg/ml Actinobacillus actinomycetemcomitans LPS, followed by further stimulation with 1 ng/ml A. actinomycetemcomitans LPS. The concentrations of interleukin-1 beta (IL-1beta), IL-6, IL-10 and tumor necrosis factor-alpha (TNF-alpha) in the culture supernatants were then determined using enzyme-linked immunosorbent assay (ELISA). In addition, intracytoplasmic cytokine staining of whole blood cells was performed for flow cytometry. RESULTS: Pretreatment with 5 pg/ml A. actinomycetemcomitans LPS significantly enhanced the production of IL-1beta and IL-6 from whole blood when further induced by 1 ng/ml LPS (1.72 times higher for IL-1beta, 2.18 times higher for IL-6 than without pretreatment). The pretreatment did not enhance the production of either TNF-alpha or IL-10. Intracytoplasmic staining showed that the monocyte fraction was primarily involved in producing IL-1beta and IL-6. Flow cytometric analysis revealed that pretreatment increased the number of IL-1beta and IL-6 producing cells as well as mean fluorescence intensity of the stained cells. CONCLUSION: A low dose of bloodstream LPS found in periodontitis patients appears to be sufficient to prime monocytes, and may be capable of affecting the systemic responses of immune and inflammatory cells.     

脂多糖对离体大鼠胰腺腺泡细胞钙稳态的影响

目的:研究脂多糖(LPS)对胰腺腺泡细胞钙稳态的影响,及胞浆内钙超载时钙离子的来源,以探讨LPS致胰腺腺泡细胞损伤的机制。方法:胶原酶法分离胰腺腺泡细胞,Fluo-3/AM负载后,在无钙或含生理钙离子浓度的培养液中加入不同浓度LPS,采用激光共聚焦显微镜观察单个胰腺腺泡细胞[Ca~(2+)]_i。另外采用MTT法检测LPS作用的不同时间点胰腺腺泡细胞的活性。结果:LPS可致胰腺腺泡细胞损伤、细胞内[Ca~(2+)]_i显著升高,且呈浓度依赖性(P<0.05):在含1mmol/L依他酸的培养液中,LPS致腺泡细胞损伤程度明显减轻(P<0.05)、仅引起胰腺腺泡细胞[Ca~(2+)]_i缓慢、微弱的升高,而再次恢复培养液中Ca~(2+)至生理浓度,引发快速、幅度更高而持久的[Ca~(2+)]_i变化。腺泡细胞内[Ca~(2+)]_i的变化明显先于腺泡细胞的损伤。结论:LPS导致胰腺腺泡细胞内钙超载,主要源于胞外Ca~(2+)内流。钙超载作为早期的病理事件参与腺泡细胞损伤的发生,钙稳态失衡是LPS致胰腺细胞损伤的主要因素之一。     

1-羟基-2,3,5-三甲氧基-酮对脂多糖致小鼠急性肺损伤的保护作用

目的探讨1-羟基-2，3，5-三甲氧基[口山]酮（QGS）对脂多糖（LPS）致小鼠急性肺损伤的保护作用及其机制。方法采用ipLPS的方法建立小鼠急性肺损伤模型。检测肺脏指数，酶法检测支气管及肺泡灌洗液（BALF）中NO水平，Westernblotting法检测核转录因子κB抑制蛋白IκB—α，诱导型一氧化氮合成酶（iNOS）及环氧合酶Ⅱ（COX-2）等蛋白的表达，HE染色观察肺组织病理学改变。结果QGS500mg／kg组能显著降低LPS引起的小鼠的肺脏指数（P〈0．05）。QGS250、500mg／kg组均能显著降低LPS致伤小鼠BALF中NO水平，抑制率分别达到了37％和48．1％。同时QGS500mg／kg组还能够明显增加肺组织中IκB—α蛋白表达量并下调iNOS及COX-2蛋白表达量。结论QGS对LPS引起的小鼠急性肺损伤有保护作用，该作用与其增加IκB—α蛋白表达而抑制iNOS和COX-2蛋白的表达有关。     

1-羟基-2，3，5-三甲氧基[口山]酮对脂多糖致小鼠急性肺损伤的保护作用

目的探讨1-羟基-2,3,5-三甲氧基■酮(QGS)对脂多糖(LPS)致小鼠急性肺损伤的保护作用及其机制。方法采用ipLPS的方法建立小鼠急性肺损伤模型。检测肺脏指数,酶法检测支气管及肺泡灌洗液(BALF)中NO水平,Western blotting法检测核转录因子κB抑制蛋白IκB-α,诱导型一氧化氮合成酶(iNOS)及环氧合酶Ⅱ(COX-2)等蛋白的表达,HE染色观察肺组织病理学改变。结果QGS500mg/kg组能显著降低LPS引起的小鼠的肺脏指数(P<0.05)。QGS250、500mg/kg组均能显著降低LPS致伤小鼠BALF中NO水平,抑制率分别达到了37%和48.1%。同时QGS500mg/kg组还能够明显增加肺组织中IκB-α蛋白表达量并下调iNOS及COX-2蛋白表达量。结论QGS对LPS引起的小鼠急性肺损伤有保护作用,该作用与其增加IκB-α蛋白表达而抑制iN-OS和COX-2蛋白的表达有关。