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

• Published in: Chinese medical journal Vol. 122; no. 5; pp. 496 - 501
• Main Authors: 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
• Format: Journal Article
• Language: English
• Published: China Departments of Pediatrics, Wayne State University School of Medicine, Detroit, MI 48201, USA 05.03.2009; Department of Medical Mycology, Institute of Dermatology,Chinese Academy of Medical Science ＆ Peking Union Medical College, Nanjing 210042, China%Developmental Therapeutics Program, Barbara Ann Karmanos Cancer Institute
• Subjects: beta-Glucans - pharmacology; Blotting, Western; Candida albicans - metabolism; Cell Line, Tumor; Cell Wall - metabolism; Enzyme-Linked Immunosorbent Assay; Gene Expression - drug effects; Humans; Hydrogen Peroxide - metabolism; Interleukin-8 - genetics; Interleukin-8 - metabolism; Lectins, C-Type; Membrane Proteins - genetics; Membrane Proteins - metabolism; Monocytes - drug effects; Monocytes - immunology; Monocytes - metabolism; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; THP; Toll-Like Receptor 2 - genetics; Tumor Necrosis Factor-alpha - genetics; Tumor Necrosis Factor-alpha - metabolism; 不溶性; 免疫反应; 实时逆转录聚合酶链反应; 急性单核细胞; 白色念珠菌; 细胞壁; 葡聚糖; Candida albicans; monocytes; Dectin-1; insoluble β-glucan; cytokines; hydrogen peroxide
• ISSN: 0366-6999; 2542-5641
• DOI: 10.3760/cma.j.issn.0366-6999.2009.05.003

Background β-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 β-glucan and induce immune responses. In this study, we sought to clarify whether insoluble β-glucan from the cell wall of C. albicans （CalG） 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 CalG in vitro. The mRNA expression of Dectin-1, Toll-like receptors （TLR2）, proinflammatory cytokine （TNF-a） 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）. H2O2 release was determined by microplate fluorescent assay. Western blotting was used to analyze IKB-a phosphorylation and degradation. Results Exposure of THP-1 monocytes to CalG led to increased gene expression and secretion of TNF-a and IL-8. CalG induced H2O2 release in a time-dependent manner. CalG hydrolyzed with zymolyase failed to induce gene expression and secretion of TNF-a, IL-8 and H2O2 release. CalG up-regulated the mRNA of Dectin-1, whereas the mRNA level of TLR2 was not altered. THP-1 monocytes challenged with CalG resulted in the activation of NF-KB in a time-dependent manner. Dectin-1 inhibitor laminarin blocked the CalG-induced production of TNF-a and H2O2 in THP-1 monocytes, but no such effect was observed in pretreatment with anti-TLR2 neutralizing antibody and the LPS inhibitor （polymyxin B）. Conclusion CalG may play a role in activation of immune responses in human THP-1 cells throuah Dectin-1, not TLR2.