Department of Dermatology and Venereology, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, China.
Chin Med J (Engl). 2013 Jan;126(2):215-9.
Trichophyton rubrum (T. rubrum) represents the most important agent of dermatophytosis in humans. T. rubrum infection causes slight inflammation, and tends to be chronic and recurrent. It is suggested that it may result from the failure of epithelial cells to recognize T. rubrum effectively and initiate effective immune responses. The C-type lectin receptors (CLR) and toll-like receptors (TLR) are the two major pattern recognition receptors (PRRs) that recognize fungal components. Therefore, the purpose of the study was to analyze the expression of those PRRs and the cytokines in HaCaT cells stimulated with heat-inactivated T. rubrum conidia and hyphae, respectively.
HaCaT cells were unstimulated or stimulated with heat-inactivated T. rubrum conidia and hyphae (1×10(6) and 1.5×10(5) colony-forming unit (CFU) in 2 ml medium, respectively) for 6, 12 and 24 hours. The mRNA expression of PRRs involved in recognizing fungal pathogen-associated molecular patterns (PAMPs) and signaling molecules were measured by quantitative reverse transcription polymerase chain reaction (RT-PCR). Meanwhile, surface toll-like receptor (TLR) 2, TLR4 and Dectin-1 were analyzed by fluorescence-activated cell sorter (FACS) 24 hours after treatment. The cytokines were detected in cell culture supernatants of HaCaT cells in 12 and 24 hours after treatment.
HaCaT cells constitutively expressed mRNA of membrane-bound TLR1, 2, 4 and 6, Dectin1 and DC-SIGN, but not Dectin-2 or Mincle. Heat-killed T. rubrum did not significantly upregulate gene transcriptions of the PRRs of HaCaT cells. Heat-inactivated T. rubrum conidia significantly reduced the surface expression of TLR2 and Dectin-1, and suppressed the secretions of interferon-inducible protein-10 (IP-10) and monocyte chemotactic protein-1 (MCP-1) of HaCaT cells, while heat-killed T. rubrum hyphae significantly induced the secretions of IP-10 and MCP-1.
The cell-wall antigens of T. rubrum fail to activate transcriptional expression of PRRs and induce a lower immune response of HaCaT cells by limited cytokines secretion.
红色毛癣菌（T. rubrum）是人类皮肤癣菌病最重要的病原体。T. rubrum 感染引起轻微炎症，且倾向于慢性和复发性。有人认为这可能是由于上皮细胞不能有效识别 T. rubrum 并启动有效的免疫反应所致。C 型凝集素受体（CLR）和 Toll 样受体（TLR）是识别真菌成分的两种主要模式识别受体（PRRs）。因此，本研究旨在分析热灭活 T. rubrum 分生孢子和菌丝分别刺激 HaCaT 细胞时，这些 PRRs 和细胞因子的表达情况。
HaCaT 细胞分别用热灭活 T. rubrum 分生孢子和菌丝（分别为 2ml 培养基中 1×10（6）和 1.5×10（5）个菌落形成单位（CFU））刺激 6、12 和 24 小时。通过实时定量逆转录聚合酶链反应（RT-PCR）测量参与识别真菌病原体相关分子模式（PAMPs）和信号分子的 PRR 的 mRNA 表达。同时，处理 24 小时后用流式细胞术（FACS）分析表面 Toll 样受体（TLR）2、TLR4 和 Dectin-1。处理后 12 和 24 小时检测 HaCaT 细胞培养上清液中的细胞因子。
HaCaT 细胞表达膜结合 TLR1、2、4 和 6、Dectin1 和 DC-SIGN，但不表达 Dectin-2 或 Mincle。热灭活 T. rubrum 对 HaCaT 细胞 PRR 的基因转录没有显著上调作用。热灭活 T. rubrum 分生孢子显著降低了 TLR2 和 Dectin-1 的表面表达，并抑制了 HaCaT 细胞干扰素诱导蛋白-10（IP-10）和单核细胞趋化蛋白-1（MCP-1）的分泌，而热灭活 T. rubrum 菌丝则显著诱导了 IP-10 和 MCP-1 的分泌。
T. rubrum 的细胞壁抗原不能激活 PRR 的转录表达，并通过有限的细胞因子分泌诱导 HaCaT 细胞产生较低的免疫反应。
