Frog urinary bladder epithelial cells express TLR4 and respond to bacterial LPS by increase of iNOS expression and L-arginine uptake
Frog urinary bladder epithelial cells express TLR4 and respond to bacterial LPS by increase of iNOS expression and L-arginine uptake
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DOI：
10.1152/ajpregu.00045.2012
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发表时间：
2012-11-01
影响因子：
2.8
通讯作者：
Parnova, Rimma
中科院分区：
文献类型：
--
作者：
Nikolaeva, Svetlana;Bachteeva, Vera;Parnova, Rimma
2005年10月27日，李文龙.蛙膀胱上皮细胞表达TLR 4，并通过增加iNOS表达和L-精氨酸摄取来响应细菌LPS。Am J Physiol Regul Integr Comp Physiol 303：R1042-R1052，2012年。首次发表于2012年9月26日; doi：10.1152/ajpregu.00045.2012.-与哺乳动物一样，两栖类膀胱上皮形成了病原体进入的屏障，是抵御侵入性微生物的第一道防线。我们研究了大肠杆菌LPS对一氧化氮（NO），一个至关重要的介质在感染过程中，由原代培养的青蛙（蛙）膀胱上皮细胞（FUBEC）的产生的影响。发现FUBEC组成型表达Toll样受体4（TLR 4），LPS的一种受体，并通过刺激诱导型一氧化氮合酶（iNOS）mRNA/蛋白质表达和NOS活性（通过培养基中产生的亚硝酸盐和瓜氨酸测定来测量）来响应LPS（10 μ g/ml）。我们的特点摄取L-精氨酸，在NO合成的前体，由FUBEC，并表明它主要是由Y（+）阳离子氨基酸转运系统介导的。LPS刺激L-精氨酸摄取，此作用可被iNOS抑制剂1400 W阻断。精氨酸酶II被发现在FUBEC中表达。（S）-（boronoethyl）-L-cysteine抑制NO合成酶活性可增加NO的生成，表明NO合成酶通过与NOS竞争底物而促进NO的生成。LPS既不改变总β-淀粉酶活性，也不改变β-淀粉酶II表达。在上皮细胞中，观察到吞噬巨噬细胞样细胞，但它们并不有助于LPS诱导的NO产生。这些数据表明，两栖类膀胱上皮细胞识别LPS，并通过刺激iNOS表达和L-精氨酸摄取增加NO的产生来对其作出反应，这似乎是调节先天免疫反应和膀胱上皮炎症所必需的。
Nikolaeva S, Bachteeva V, Fock E, Herterich S, Lavrova E, Borodkina A, Gambaryan S, Parnova R. Frog urinary bladder epithelial cells express TLR4 and respond to bacterial LPS by increase of iNOS expression and L-arginine uptake. Am J Physiol Regul Integr Comp Physiol 303: R1042-R1052, 2012. First published September 26, 2012; doi:10.1152/ajpregu.00045.2012.-As in mammals, epithelium of the amphibian urinary bladder forms a barrier to pathogen entry and is a first line of defense against penetrating microorganisms. We investigated the effect of Escherichia coli LPS on generation of nitric oxide (NO), a critically important mediator during infectious processes, by primary cultured frog (Rana temporaria) urinary bladder epithelial cells (FUBEC). It was found that FUBEC constitutively express Toll-like receptor 4 (TLR4), a receptor of LPS, and respond to LPS (10 mu g/ml) by stimulation of inducible nitric oxide synthase (iNOS) mRNA/protein expression and NOS activity measured by nitrite produced in the culture medium and by citrulline assay. We characterized uptake of L-arginine, a precursor in NO synthesis, by FUBEC and showed that it is mediated mainly by the y(+) cationic amino acid transport system. LPS stimulated L-arginine uptake, and this effect was blocked by the iNOS inhibitor 1400W. Arginase II was found to be expressed in FUBEC. Inhibition of arginase activity by (S)-(boronoethyl)-L-cysteine increased generation of NO, suggesting contribution of arginase to NO production via competing with NOS for the substrate. LPS altered neither total arginase activity nor arginase II expression. Among epithelial cells, phagocytic macrophage-like cells were observed, but they did not contribute to LPS-induced NO production. These data demonstrate that amphibian urinary bladder epithelial cells recognize LPS and respond to it by increased generation of NO via stimulation of iNOS expression and L-arginine uptake, which appears to be essential for the regulation of the innate immune response and the inflammation in bladder epithelium.