白色念珠菌细胞壁中的不溶性β-葡聚糖通过Dectin-1诱导人THP-1单核细胞的免疫反应。

Insoluble beta-glucan from the cell wall of Candida albicans induces immune responses of human THP-1 monocytes through Dectin-1.

作者信息

Li Min, Liu Ze-hu, Chen Qing, Zhou Wu-qing, Yu Mei-wen, Lü Gui-xia, Lü Xue-lian, Shen Yong-nian, Liu Wei-da, Wu Shao-xi

机构信息

Department of Medical Mycology, Institute of Dermatology, Chinese Academy of Medical Science & Peking Union Medical College, Nanjing, China.

出版信息

Chin Med J (Engl). 2009 Mar 5;122(5):496-501.

PMID:19323897

Abstract

BACKGROUND

beta-glucan is the major structure component of Candida albicans (C. albicans) cell wall. It has been demonstrated that Dectin-1 as the principal C-type lectin pattern-recognition receptor (PRR) can recognize fungal beta-glucan and induce immune responses. In this study, we sought to clarify whether insoluble beta-glucan from the cell wall of C. albicans (CaIG) could induce immune responses in human THP-1 monocytes (a human acute monocytic leukemia cell line) and to determine the underlying mechanisms.

METHODS

Human THP-1 monocytes were challenged with CaIG in vitro. The mRNA expression of Dectin-1, Toll-like receptors (TLR2), proinflammatory cytokine (TNF-alpha) and chemokine (IL-8) was assayed by real-time reverse transcription polymerase chain reaction (RT-PCR). The secretion of TNF-a and IL-8 were measured by enzyme-linked immunosorbent assay (ELISA). H(2)O(2) release was determined by microplate fluorescent assay. Western blotting was used to analyze IkappaB-a phosphorylation and degradation.

RESULTS

Exposure of THP-1 monocytes to CaIG led to increased gene expression and secretion of TNF-alpha and IL-8. CaIG induced H(2)O(2) release in a time-dependent manner. CaIG hydrolyzed with zymolyase failed to induce gene expression and secretion of TNF-alpha, IL-8 and H(2)O(2) release. CaIG up-regulated the mRNA of Dectin-1, whereas the mRNA level of TLR2 was not altered. THP-1 monocytes challenged with CaIG resulted in the activation of NF-kappaB in a time-dependent manner. Dectin-1 inhibitor laminarin blocked the CaIG-induced production of TNF-alpha and H(2)O(2) in THP-1 monocytes, but no such effect was observed in pretreatment with anti-TLR2 neutralizing antibody and the LPS inhibitor (polymyxin B).

CONCLUSION

CaIG may play a role in activation of immune responses in human THP-1 cells through Dectin-1, not TLR2.

摘要

背景

β-葡聚糖是白色念珠菌细胞壁的主要结构成分。已证实，作为主要C型凝集素模式识别受体（PRR）的Dectin-1可识别真菌β-葡聚糖并诱导免疫反应。在本研究中，我们试图阐明白色念珠菌细胞壁中的不溶性β-葡聚糖（CaIG）是否能在人THP-1单核细胞（一种人急性单核细胞白血病细胞系）中诱导免疫反应，并确定其潜在机制。

方法

体外用人THP-1单核细胞与CaIG进行刺激。通过实时逆转录聚合酶链反应（RT-PCR）检测Dectin-1、Toll样受体（TLR2）、促炎细胞因子（TNF-α）和趋化因子（IL-8）的mRNA表达。通过酶联免疫吸附测定（ELISA）检测TNF-α和IL-8的分泌。用微孔板荧光测定法测定H₂O₂释放。采用蛋白质印迹法分析IκB-α的磷酸化和降解。

结果

THP-1单核细胞暴露于CaIG导致TNF-α和IL-8的基因表达及分泌增加。CaIG以时间依赖性方式诱导H₂O₂释放。用溶菌酶水解的CaIG未能诱导TNF-α、IL-8的基因表达及分泌以及H₂O₂释放。CaIG上调了Dectin-1的mRNA，而TLR2的mRNA水平未改变。用CaIG刺激THP-1单核细胞导致NF-κB以时间依赖性方式激活。Dectin-1抑制剂海带多糖可阻断CaIG诱导的THP-1单核细胞中TNF-α和H₂O₂的产生，但在用抗TLR2中和抗体和LPS抑制剂（多粘菌素B）预处理时未观察到这种效果。