Cytokine Gene Expression Occurs More Rapidly in Stimulated Peripheral Blood Mononuclear Cells from Human Immunodeficiency Virus-Infected Persons

Evaluation of cytokine gene expression following in vitro stimulation is one means of examining the dysregulation of the immune system in human immunodeficiency virus (HIV) infection. We have assessed differences in the immune status of non-HIV-infected (HIV−) and HIV-infected (HIV+) individuals by evaluating the kinetics of the expression of cytokine genes. We compared detailed time courses of cytokine mRNA expression in HIV− and HIV+ peripheral blood mononuclear cells (PBMC) and found that there is a significant shift (P < 0.01) for all cytokines examined (interleukin 2 [IL-2], IL-6, IL-10, gamma interferon, and tumor necrosis factor alpha [TNF-α]) to an earlier time of mean peak mRNA expression by HIV+ PBMC (between 4 and 8 h) compared to HIV− PBMC (8 h) in response to either phytohemagglutinin (PHA) or anti-CD3 stimulation. Additional studies showed that although PHA-stimulated HIV+ PBMC showed decreased median IL-2, IL-4, and TNF-α mRNA levels, they typically demonstrated more rapid kinetics (increased mean 4-h/24-h cytokine mRNA ratios), with significant differences for IL-4 (P < 0.05) and TNF-α (P < 0.005), compared to HIV− PBMC. The use of fresh or frozen cells gave comparable cytokine mRNA data; however, the secretion of some cytokine proteins (IL-2 receptor, IL-10, and TNF-α) appeared to be reduced in HIV+ PBMC that had been frozen and thawed. Our studies demonstrate that the kinetics of cytokine gene expression can reveal additional dysregulation of the immune system in HIV infection, suggesting that PBMC of HIV-infected persons exist in an activated state in vivo that permits them to express cytokine genes more rapidly than a normal PBMC.

体外刺激后细胞因子（cytokine）基因表达的检测，是探究人类免疫缺陷病毒（human immunodeficiency virus, HIV）感染引发免疫系统失调的常用手段之一。本研究通过分析细胞因子基因表达的动力学（kinetics）特征，对比评估了HIV未感染者（HIV阴性，HIV−）与HIV感染者（HIV阳性，HIV+）的免疫状态差异。我们对比了HIV阴性与HIV阳性个体外周血单个核细胞（peripheral blood mononuclear cells, PBMC）中细胞因子信使核糖核酸（mRNA）表达的完整时间进程，结果显示：经植物血凝素（phytohemagglutinin, PHA）或抗CD3刺激后，所有检测的细胞因子（包括白细胞介素2（interleukin 2, IL-2）、IL-6、IL-10、γ干扰素及肿瘤坏死因子α（tumor necrosis factor alpha, TNF-α））的HIV阳性PBMC的平均mRNA表达峰值时间（4~8小时），均较HIV阴性PBMC的8小时显著提前，差异具有统计学意义（P < 0.01）。后续补充研究表明，尽管经PHA刺激的HIV阳性PBMC的IL-2、IL-4及TNF-α的mRNA水平中位数（median）有所降低，但相较于HIV阴性PBMC，其细胞因子表达动力学普遍更快（平均4小时/24小时细胞因子mRNA比值升高），其中IL-4（P < 0.05）与TNF-α（P < 0.005）的差异尤为显著。使用新鲜或冻存细胞获取的细胞因子mRNA数据结果基本一致；但经冻融处理的HIV阳性PBMC中，部分细胞因子蛋白（包括IL-2受体、IL-10及TNF-α）的分泌量似乎有所下降。本研究证实，细胞因子基因表达的动力学特征可揭示HIV感染中免疫系统额外的失调情况，提示HIV感染者的PBMC在体内处于活化状态，使其细胞因子基因的表达速度快于正常PBMC。