Multiple TLRs are expressed in human cholangiocytes and mediate host epithelial defense responses to Cryptosporidium parvum via activation of NF-κB
Multiple TLRs are expressed in human cholangiocytes and mediate host epithelial defense responses to Cryptosporidium parvum via activation of NF-κB
复制标题
多种 TLRs 在人胆管细胞中表达，并通过激活 NF-κB 介导宿主上皮细胞对副隐孢子虫的防御反应
DOI：
10.4049/jimmunol.175.11.7447
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发表时间：
2005-12-01
影响因子：
4.4
通讯作者：
LaRusso, NF
中科院分区：
文献类型：
--
作者：
Chen, XM;O'Hara, SP;LaRusso, NF
微小隐孢子虫（Cryptosporidium parvum）感染上皮细胞可引发宿主细胞的多种先天性和适应性免疫应答，包括细胞因子/趋化因子的释放和抗微生物肽的上调。触发这些宿主细胞反应的机制尚不清楚。因此，我们评估了TLR在C.培养的人胆管上皮细胞的细小病毒感染（即，胆管细胞）。我们发现正常人胆管细胞表达所有已知的TLR。C.培养的胆管细胞的细小病毒感染诱导TLR 2和TLR 4选择性募集到感染部位。在感染的细胞中检测到TLR的几种下游效应物的激活，包括IL-1 R相关激酶、p-38和NF-κ B。用TLR 2和TLR 4的显性失活突变体以及衔接分子髓样分化蛋白88（MyD 88）转染胆管细胞，抑制了C. parvum诱导的IL-1 R相关激酶、p-38和NF-κ B活化。TLR 2、TLR 4和MyD 88的短干扰RNA也阻断了小隐孢子虫诱导的NF-κ B活化。此外，在直接感染的细胞中，小隐孢子虫选择性地上调人β-防御素-2，并且抑制TLR 2和TLR 4信号或NF-κ B活化均与C的减少相关。parvum诱导的人β-防御素-2表达。在初始暴露于寄生虫后48-96 h，在用MyD 88显性阴性突变体转染的细胞中检测到的寄生虫数量显著高于对照细胞，表明MyD 88缺陷型细胞更容易感染。这些发现表明胆管细胞表达多种TLRs，并提示TLR 2和TLR 4介导胆管细胞对C.通过激活NF-κ B对细小病毒的作用。
Infection of epithelial cells by Cryptosporidium parvum triggers a variety of host-cell innate and adaptive immune responses including release of cytokines/chemokines and up-regulation of antimicrobial peptides. The mechanisms that trigger these host-cell responses are unclear. Thus, we evaluated the role of TLRs in host-cell responses during C. parvum infection of cultured human biliary epithelia (i.e., cholangiocytes). We found that normal human cholangiocytes express all known TLRs. C. parvum infection of cultured cholangiocytes induces the selective recruitment of TLR2 and TLR4 to the infection sites. Activation of several downstream effectors of TLRs including IL-1R-associated kinase, p-38, and NF-kappa B was detected in infected cells. Transfection of cholangiocytes with dominant-negative mutants of TLR2 and TLR4, as well as the adaptor molecule myeloid differentiation protein 88 (MyD88), inhibited C. parvum-induced activation of IL-1R-associated kinase, p-38, and NF-kappa B. Short-interfering RNA to TLR2, TLR4, and MyD88 also blocked C parvum-induced NF-kappa B activation. Moreover, C parvum selectively up-regulated human beta-defensin-2 in directly infected cells, and inhibition of TLR2 and TLR4 signals or NF-kappa B activation were each associated with a reduction of C. parvum-induced human beta-defensin-2 expression. A significantly higher number of parasites were detected in cells transfected with a MyD88 dominant-negative mutant than in the control cells at 48-96 h after initial exposure to parasites, suggesting MyD88-deficient cells were more susceptible to infection. These findings demonstrate that cholangiocytes express a variety of TLRs, and suggest that TLR2 and TLR4 mediate cholangiocyte defense responses to C. parvum via activation of NF-kappa B.