Müller Loretta, Chehrazi Claire V E, Henderson Michael W, Noah Terry L, Jaspers Ilona
Part Fibre Toxicol. 2013 Apr 24;10:16. doi: 10.1186/1743-8977-10-16.
Natural killer (NK) cells are an important lymphocyte population in the nasal mucosa and play important roles in linking the innate and the adaptive immune response. Their two main functions are direct cell-mediated cytotoxicity and the release of cytokines. They are important during viral infections and cancer. Due to their location in the nasal mucosa, NK cells are likely exposed to inhaled pollutants, such as diesel exhaust. Whether and how exposure to diesel exhaust particles (DEP) affects NK cell function in the context of viral infections has not been investigated.
NK cells were isolated from peripheral blood obtained from normal healthy volunteers and subsequently stimulated with the viral mimetic polyinosinic:polycytidylic acid (pI:C), DEP, or pI:C+DEP for 18 hours. NK cells were subsequently analyzed for changes in surface marker expression, cytokine production, gene expression changes, and cytotoxic function using flow cytometry, ELISA, qRT-PCR, and cell-mediated cytotoxicity assay, respectively.
Stimulation of NK cells with pI:C and pI:C+DEP, but not DEP alone, increased the release of IL-1β, IL-2, IL-4, IL-8, IL-10, IL-12p70, IFN-γ and TNF-α. As compared to pI:C alone or pI:C+DEP, the release of IL-1β, IL-8 and TNF-α was significantly lower after DEP stimulation alone. Stimulation with pI:C alone increased the gene and protein expression of granzyme B and perforin, which was completely blunted by adding DEP. Addition of DEP further reduced CD16 expression in pI:C stimulated cells. Similarly, cell-mediated cytotoxicity was significantly reduced by the addition of DEP.
In the context of viral infection, DEP potentially reduces NK cells' ability to kill virus-infected host cells, in spite of normal cytokine levels, and this may increase susceptibility to viral infections . This reduction in the potential ability of NK cells to kill virus-infected host cells may increase the susceptibility to viral infections after DEP exposure.
自然杀伤（NK）细胞是鼻黏膜中重要的淋巴细胞群体，在连接固有免疫和适应性免疫反应中发挥重要作用。它们的两个主要功能是直接的细胞介导的细胞毒性和细胞因子的释放。它们在病毒感染和癌症期间很重要。由于它们位于鼻黏膜中，NK细胞很可能暴露于吸入的污染物，如柴油废气。在病毒感染的情况下，接触柴油废气颗粒（DEP）是否以及如何影响NK细胞功能尚未得到研究。
从正常健康志愿者获得的外周血中分离NK细胞，随后用病毒模拟物聚肌苷酸：聚胞苷酸（pI:C）、DEP或pI:C + DEP刺激18小时。随后分别使用流式细胞术、酶联免疫吸附测定（ELISA）、定量逆转录聚合酶链反应（qRT-PCR）和细胞介导的细胞毒性测定分析NK细胞表面标志物表达、细胞因子产生、基因表达变化和细胞毒性功能的变化。
用pI:C和pI:C + DEP刺激NK细胞，但单独用DEP刺激则不会，会增加白细胞介素-1β（IL-1β）、白细胞介素-2（IL-2）、白细胞介素-4（IL-4）、白细胞介素-8（IL-8）、白细胞介素-10（IL-10）、白细胞介素-12p70、干扰素-γ（IFN-γ）和肿瘤坏死因子-α（TNF-α）的释放。与单独用pI:C或pI:C + DEP相比，单独用DEP刺激后IL-1β、IL-8和TNF-α的释放显著降低。单独用pI:C刺激会增加颗粒酶B和穿孔素的基因和蛋白表达，而添加DEP会完全抑制这种表达。添加DEP进一步降低了pI:C刺激细胞中的CD16表达。同样，添加DEP会显著降低细胞介导的细胞毒性。
在病毒感染的情况下，尽管细胞因子水平正常，但DEP可能会降低NK细胞杀死病毒感染宿主细胞的能力，这可能会增加对病毒感染的易感性。NK细胞杀死病毒感染宿主细胞的潜在能力降低可能会增加DEP暴露后对病毒感染的易感性。
