Potentiation and tolerance of toll-like receptor priming in human endothelial cells

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• 作者：Stephen R. Koch^a ; Fred S. Lamb^a ; Judith Hellman^b ; Edward R. Sherwood^c ; Ryan J. Stark^a ; ^{ryan.stark@vanderbilt.edu}
• 关键词：ELISA ; enzyme-linked immunosorbent assay ; ERK ; extracellular signal-regulated kinase ; HMVEC ; human dermal microvascular endothelial cell ; HUVEC ; human umbilical vein endothelial cell ; IL-6 ; interleukin 6 ; IKK ; IκB kinase ; IP-10 ; interferon gamma-induced protein 10 ; IRF ; interferon regulatory factor ; JNK ; c-Jun amino-terminal kinase ; LPS ; lipopolysaccharide ; LTA ; lipoteichoic acid ; MAPK ; mitogen-activated protein kinase ; MyD88 ; myeloid differentiation primary response gene 88 ; Nec-1s ; 7-Cl-O-Nec1
• 刊名：Translational Research
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：180
• 期：Complete
• 页码：53-67.e4
• 全文大小：2349 K
• 卷排序：180

文摘

Repeated challenge of lipopolysaccharide (LPS) alters the response to subsequent LPS exposures via modulation of toll-like receptor 4 (TLR4). Whether activation of other TLRs can modulate TLR4 responses, and vice versa, remains unclear. Specifically with regards to endothelial cells, a key component of innate immunity, the impact of TLR cross-modulation is unknown. We postulated that TLR2 priming (via Pam3Csk4) would inhibit TLR4-mediated responses while TLR3 priming (via Poly I:C) would enhance subsequent TLR4-inflammatory signaling. We studied human umbilical vein endothelial cells (HUVECs) and neonatal human dermal microvascular endothelial cells (HMVECs). Cells were primed with a combination of Poly I:C (10 μg/ml), Pam3Csk4 (10 μg/ml), or LPS (100 ng/ml), then washed and allowed to rest. They were then rechallenged with either Poly I:C, Pam3Csk4 or LPS. Endothelial cells showed significant tolerance to repeated LPS challenge. Priming with Pam3Csk4 also reduced the response to secondary LPS challenge in both cell types, despite a reduced proinflammatory response to Pam3Csk4 in HMVECs compared to HUVECs. Poly I:C priming enhanced inflammatory and interferon producing signals upon Poly I:C or LPS rechallenge, respectively. Poly I:C priming induced interferon regulatory factor 7, leading to enhancement of interferon production. Finally, both Poly I:C and LPS priming induced significant changes in receptor-interacting serine/threonine-protein kinase 1 activity. Pharmacological inhibition of receptor-interacting serine/threonine-protein kinase 1 or interferon regulatory factor 7 reduced the potentiated phenotype of TLR3 priming on TLR4 rechallenge. These results demonstrate that in human endothelial cells, prior activation of TLRs can have a significant impact on subsequent exposures and may contribute to the severity of the host response.