探討Siglec-5及Siglec-14受體對單核球細胞之抗病毒免疫反應的調控作用

To investigate the role of Siglec-5 and Siglec-14 in the monocyte-mediated antiviral immune response

藍子晴(Tzu-Ching Lan)

指導教授 ： 張永祺

國立臺灣大學/醫學院/微生物學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202102538

摘要

Sialic acid-binding immunoglobulin-like lectin (Siglec)是一種廣泛表現在不同免疫細胞表面的受體，可辨識不同病原體，並引起相對應免疫反應，其中Siglec-5和Siglec-14均可表現於人類單核球細胞，且他們因可辨識相同配體，但傳遞相反訊號，因此被稱為「成對受體」。過去發現在細菌感染時，表現SIGLEC14 allele的個體會有較明顯的發炎反應，在我們的實驗中亦發現，穩定表現Siglec-14的THP-1 (S14/THP-1)受病毒感染後，也會產生較多的促炎性細胞激素，但與抗病毒反應有關的IFN-β表現卻較低。為了解Siglec是透過何種分子機制，調控了THP-1細胞的免疫反應，我們首先利用NanoString nCounter Human Immunology Panel分析當S5/THP-1、S14/THP-1受病毒感染後，細胞內免疫相關基因之表現量的改變。接著我們逐一分析與病毒感染導致之發炎反應相關的訊息傳遞路徑，我們發現與S5/ THP-1相比，S14/THP-1內ERK/ RSK1/ p65路徑及SYK，均有較活化的情形。而在與調控IFN-β表現相關的路徑中，雖然S5/THP-1和S14/THP-1在TBK1及IRF3的活化情況並無顯著差異，但我們發現在S14/ THP-1中，GSK3β的活化受到抑制，且β-catenin在細胞內有較明顯累積的情形，可能因此抑制了IRF3對IFN-β的轉錄活性。總結實驗結果，我們初步發現在病毒感染時，成對受體Siglec-5和Siglec-14對免疫反應之分子機制的調控作用。

關鍵字

Siglecs ； THP-1 ； A型流感病毒 ； 仙台病毒 ； 先天性免疫反應 ； 抗病毒免疫反應 ； 促炎性細胞激素 ； 第一型干擾素

並列摘要

Sialic acid-binding immunoglobulin-like lectin (Siglec) is a novel family of immuno-regulatory receptors expressing on various immune cells. Human monocytes express both Siglec-5 and Siglec-14, a paired receptor transduces opposite signaling when engaging by the same ligand. Individuals with an activating SIGLEC14 allele are prone to elicit stronger inflammation upon bacterial infection. Unexpectedly, we found that human THP-1 cells stably transfected with Siglec-14 generated increased proinflammatory cytokines but reduced antiviral cytokine IFN-β upon viral infection. In order to understand the molecular mechanisms underlying this Siglec-skewed immune responses, we first profiled the expression of immune‐related genes in THP-1 cells expressing Siglec-5 or Siglec-14 after viral infection using the NanoString nCounter Human Immunology Panel. Next, I carefully examined several signaling pathways previously suggested to participate in virus-related inflammatory responses. I found that the activation of ERK/ RSK1/ p65 pathway and SYK was stronger in Siglec-14-expressing THP-1 cells, compared to Sigec-5-expressing THP-1 cells. Although similar phosphorylation level of TBK1 and IRF3 were detected in Siglec-5 and Siglec-14 expressing THP-1 cells, reduced activation of GSK3β and accumulated β-catenin was observed in Siglec-14-expressing THP-1 cells, which likely acts via reducing IRF3-dependent IFN-β transcription. Collectively, our data provide initial evidence of immunoregulatory role of paired Siglec receptors in regulating host anti-viral responses.

並列關鍵字

Siglecs ； THP-1 ； influenza A virus ； Sendai virus ； innate immune responses ； antiviral immune responses ； proinflammatory cytokines ； type I IFN

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