Amarante Marla Karine, Oda Julie Massayo Maeda, Reiche Edna Maria Vissoci, Morimoto Helena Kaminami, Aoki Mateus Nobrega, Watanabe Maria Angelica Ehara
Department of Pathological Sciences, Biological Sciences Center, and.
Exp Ther Med. 2011 Sep;2(5):925-929. doi: 10.3892/etm.2011.303. Epub 2011 Jun 30.
Toll-like receptors (TLRs), a family of mammalian receptors, are able to recognize nucleic acids. TLR3 recognizes double-stranded (ds)RNA, a product of the replication of certain viruses. Polyinosinic-polycytidylic acid, referred to as poly(I:C), an analog of viral dsRNA, interacts with TLR3 thereby eliciting immunoinflammatory responses characteristic of viral infection or down-regulating the expression of chemokine receptor CXCR4. It is known that dsRNA also directly activates interferon (IFN)-induced enzymes, such as the RNA-dependent protein kinase (PKR). In the present study, the mRNA expression of TLR3, CXCR4, IFNγ and PKR was investigated in a culture of peripheral blood mononuclear cells (PBMCs) stimulated with poly(I:C) and endogenous RNA from human PBMCs. No cytotoxic effect on the cells or on the proliferation of CD3(+), CD4(+) and CD8(+) cells was observed. TLR3 expression in the PBMCs in the presence of poly(I:C) was up-regulated 9.5-fold, and TLR3 expression in the PBMCs treated with endogenous RNA was down-regulated 1.8-fold (p=0.002). The same trend was observed for IFNγ where in the presence of poly(I:C) an 8.7-fold increase was noted and in the presence of endogenous RNA a 3.1-fold decrease was observed. In the culture activated with poly(I:C), mRNA expression of CXCR4 increased 8.0-fold and expression of PKR increased 33.0-fold. Expression of these genes decreased in the culture treated with endogenous RNA when compared to the culture without stimulus. Thus, high expression of mRNA for TLR3, IFNγ, CXCR4 and PKR was observed in the presence of poly(I:C) and low expression was observed in the cells cultured with endogenous RNA. In conclusion, TLR3 may play major physiological roles that are not in the context of viral infection. It is possible that RNA released from cells could contain enough double-stranded structures to regulate cell activation. The involvement of endogenous RNA in endogenous gene expression and its implications in the regulation thereof, are still being studied, and will have significant implications in the future.
Toll样受体（TLRs）是一类哺乳动物受体，能够识别核酸。TLR3可识别双链（ds）RNA，这是某些病毒复制的产物。聚肌苷酸-聚胞苷酸，简称为聚（I:C），作为病毒dsRNA的类似物，与TLR3相互作用，从而引发病毒感染特有的免疫炎症反应或下调趋化因子受体CXCR4的表达。已知dsRNA还可直接激活干扰素（IFN）诱导的酶，如RNA依赖性蛋白激酶（PKR）。在本研究中，研究了在用聚（I:C）和来自人外周血单核细胞（PBMCs）的内源性RNA刺激的外周血单核细胞（PBMCs）培养物中TLR3、CXCR4、IFNγ和PKR的mRNA表达。未观察到对细胞或CD3(+)、CD4(+)和CD8(+)细胞增殖的细胞毒性作用。在存在聚（I:C）的情况下，PBMCs中TLR3的表达上调了9.5倍，而用内源性RNA处理的PBMCs中TLR3的表达下调了1.8倍（p = 0.002）。IFNγ也观察到相同的趋势，在存在聚（I:C）的情况下增加了8.7倍，在存在内源性RNA的情况下减少了3.1倍。在用聚（I:C）激活的培养物中，CXCR4的mRNA表达增加了8.0倍，PKR的表达增加了33.0倍。与未刺激的培养物相比，在用内源性RNA处理的培养物中这些基因的表达下降。因此，在存在聚（I:C）的情况下观察到TLR3、IFNγ、CXCR4和PKR的mRNA高表达，而在用内源性RNA培养的细胞中观察到低表达。总之，TLR3可能发挥主要的生理作用，而不是在病毒感染的背景下。细胞释放的RNA可能含有足够的双链结构来调节细胞活化。内源性RNA参与内源性基因表达及其在调控中的意义仍在研究中，并且在未来将具有重要意义。
