Circulating leukocyte transcriptional signatures in HIV patients with impaired gas exchange. Homo sapiens

Background: HIV infection is associated with impaired gas transfer in the lung as indicated by a low diffusing capacity (DLCO). Mechanisms for reduced DLCO in the setting of HIV infection are not well understood. We hypothesized that HIV-associated gas exchange impairment is indicative of system-wide perturbations that could be reflected by alterations in peripheral blood gene expression. Methods: A total of 40 HIV-infected (HIV+) and uninfected (HIV-) men with preserved versus reduced DLCO were selected from a larger cohort study of lung function. All subjects were current smokers and those with acute illness, lung diseases other than COPD or asthma were excluded. Total RNA was extracted from peripheral blood leukocytes (PBLs) and hybridized to whole-genome microarrays. Gene set enrichment analysis (GSEA) was performed between HIV+ vs. HIV- subjects with preserved DLCO and those with impaired DLCO to identify differentially activated pathways. Results: Using pathway-based analyses we found that in subjects with preserved DLCO, HIV infection is associated with activation of processes involved in immunity, cell cycle, and apoptosis. When we applied a similar analysis to subjects with low DLCO, we identified a much broader repertoire of inflammatory and immune-related pathways in HIV+ patients relative to HIV- subjects, with up-regulation of multiple interleukin pathways, interferon signaling, Toll-like receptor signaling, and T cell/B cell receptor signaling. We confirmed elevated circulating levels of IL-6 in HIV+ patients with reduced DLCO relative to the other groups. Conclusions: Our findings reveal that PBLs of subjects with HIV infection and low DLCO are distinguished by widespread enrichment of immuno-inflammatory programs. Activation of these pathways may alter the biology of circulating leukocytes and play a role in the pathogenesis of HIV-associated pulmonary gas exchange impairment. Overall design: Total RNA was isolated from peripheral blood leukocytes in four subject groups: 1. HIV-, low DLCO (N = 11); 2. HIV+, low DLCO (N = 10); 3. HIV-, preserved DLCO (N = 9); 4. HIV+, preserved DLCO (N = 9). Each sample was hybridized to an Affymetrix PrimeView Human Gene Expression microarray for a total of 39 experiments.

背景：HIV感染与肺部气体交换功能受损密切相关，其临床特征为弥散功能（diffusing capacity, DLCO）降低。目前对于HIV感染情境下DLCO降低的具体发病机制尚不明确。本研究提出假说：HIV相关的气体交换受损可反映全身层面的分子紊乱，这种紊乱可通过外周血基因表达的改变得以体现。
方法：本研究从一项更大规模的肺功能队列研究中筛选出40名男性受试者，其中包括HIV感染者（HIV+）与未感染者（HIV-），按照DLCO水平分为弥散功能保留组与弥散功能受损组。所有受试者均为当前吸烟者，排除合并急性疾病、慢性阻塞性肺疾病（COPD）或哮喘以外的其他肺部疾病者。从外周血白细胞（peripheral blood leukocytes, PBLs）中提取总RNA，并与全基因组微阵列进行杂交。针对DLCO保留组的HIV+与HIV-受试者，以及DLCO受损组的HIV+与HIV-受试者，分别进行基因集富集分析（gene set enrichment analysis, GSEA），以筛选出差异激活的信号通路。
结果：基于通路的分析显示，在DLCO保留的受试者中，HIV感染与免疫、细胞周期及细胞凋亡相关生物学过程的激活相关。当对DLCO降低的受试者进行同类分析时，相较于HIV-受试者，HIV+患者中鉴定出的炎症与免疫相关通路范围更广，包括多条白介素通路、干扰素信号通路、Toll样受体信号通路以及T/B细胞受体信号通路的上调。我们进一步验证发现，相较于其他组别，DLCO降低的HIV+患者外周血中IL-6水平显著升高。
结论：本研究结果表明，合并DLCO降低的HIV感染受试者的外周血白细胞，其分子特征为广泛富集免疫炎症相关程序。这些通路的激活可改变循环白细胞的生物学特性，并可能参与HIV相关肺部气体交换受损的发病机制。
整体实验设计：从4组受试者的外周血白细胞中分离总RNA：1. HIV-、DLCO降低组（N=11）；2. HIV+、DLCO降低组（N=10）；3. HIV-、DLCO保留组（N=9）；4. HIV+、DLCO保留组（N=9）。每个样本均与Affymetrix PrimeView人类基因表达微阵列进行杂交，共完成39次实验。