The effects of electronic cigarette (e-cigarette) vapor (EV) exposure on the physiology of respiratory microflora are not fully defined. We analyzed the effects of exposure to vapor from nicotine-containing and nicotine-free e-liquid formulations on the virulence and transcriptome of Streptococcus pneumoniae strain TIGR4, a pathogen that asymptomatically colonizes the human nasopharyngeal mucosa. TIGR4 was preexposed for 2 h to nicotine-containing EV extract (EVE^+NIC), nicotine-free EV extract (EVE^–NIC), cigarette smoke extract (CSE), or nutrient-rich tryptic soy (TS) broth (control). The differences between the treatment and control strains were explored using transcriptome sequencing (RNA sequencing [RNA-Seq]), in vitro virulence assays, and an in vivo mouse model of acute pneumonia. The analysis of RNA-Seq profiles revealed modest changes in the expression of 14 genes involved in sugar transport and metabolism in EVE^–NIC-preexposed TIGR4 compared to the control, while EVE^+NIC or CSE exposure altered expression of 264 and 982 genes, respectively, most of which were involved in metabolism and stress response. Infection in a mouse model of acute pneumonia with control TIGR4 or with TIGR4 preexposed to EVE^+NIC, EVE^–NIC, or CSE did not show significant differences in disease parameters, such as bacterial organ burden and respiratory cytokine response. Interestingly, TIGR4 exposed to CSE or EVE^+NIC (but not EVE^–NIC) exhibited moderate induction of biofilm formation. However, none of the treatment groups showed significant alterations in pneumococcal hydrophobicity or epithelial cell adherence. In summary, our study reports that exposure to EV significantly alters the S. pneumoniae transcriptome in a nicotine-dependent manner without affecting pneumococcal virulence.

IMPORTANCE With the increasing popularity of e-cigarettes among cigarette smoking and nonsmoking adults and children and the recent reports of vaping-related lung illness and deaths, further analysis of the adverse health effects of e-cigarette vapor (EV) exposure is warranted. Since pathogenic bacteria such as Streptococcus pneumoniae can colonize the human nasopharynx as commensals, they may be affected by exposure to bioactive chemicals in EV. Hence, in this study we examined the effects of EV exposure on the physiology of S. pneumoniae strain TIGR4. In order to differentiate between the effects of nicotine and nonnicotine components, we specifically compared the RNA-Seq profiles and virulence of TIGR4 exposed to vapor from nicotine-containing and nicotine-free e-liquid formulations. We observed that nicotine-containing EV augmented TIGR4 biofilms and altered expression of TIGR4 genes predominantly involved in metabolism and stress response. However, neither nicotine-containing nor nicotine-free EV affected TIGR4 virulence in a mouse model.

电子香烟（电子烟）蒸气（EV）暴露对呼吸道菌群生理的影响尚未完全确定。我们分析了暴露于含尼古丁和无尼古丁的电子液体制剂的蒸气对肺炎链球菌菌株TIGR4（一种无症状地定居于人鼻咽粘膜的病原体）的毒力和转录组的影响。TIGR4预先暴露于含尼古丁的EV提取物（EVE ^{+ NIC}），不含尼古丁的EV提取物（EVE ^–NIC），香烟烟雾提取物（CSE）或营养丰富的胰蛋白酶大豆（TS）肉汤中2小时（对照）。使用转录组测序（RNA测序[RNA-Seq]）在体外探索了治疗菌株和对照菌株之间的差异毒力测定和急性肺炎的体内小鼠模型。RNA-Seq图谱分析显示，与对照相比，EVE ^–NIC暴露的TIGR4中参与糖转运和代谢的14个基因的表达与对照相比有适度变化，而EVE ^{+ NIC}或CSE暴露分别改变了264和982基因的表达。 ，其中大部分与新陈代谢和压力反应有关。用对照TIGR4或预先暴露于EVE ^{+ NIC}，EVE ^-NIC或CSE的TIGR4在急性肺炎的小鼠模型中的感染在疾病参数（如细菌器官负担和呼吸道细胞因子反应）上没有显着差异。有趣的是，TIGR4暴露于CSE或EVE ^{+ NIC}（但不是EVE ^–NIC）表现出中等程度的生物膜形成诱导作用。但是，没有一个治疗组在肺炎球菌疏水性或上皮细胞粘附方面显示出显着改变。总之，我们的研究报告说，暴露于EV以尼古丁依赖性方式显着改变肺炎链球菌的转录组，而不会影响肺炎球菌的毒力。

重要信息随着电子烟在吸烟和不吸烟的成年人和儿童中的日益普及，以及有关与电子烟相关的肺部疾病和死亡的最新报道，有必要进一步分析电子烟蒸气（EV）暴露对健康的不利影响。由于诸如肺炎链球菌之类的致病细菌可以作为人类的鼻咽菌群定殖，因此它们可能会因接触电动汽车中的生物活性化学物质而受到影响。因此，在这项研究中，我们研究了EV暴露对肺炎链球菌生理的影响TIGR4株。为了区分尼古丁成分和非尼古丁成分的影响，我们专门比较了暴露于含尼古丁和无尼古丁的电子液体制剂的蒸气中的TIGR4的RNA-Seq图谱和毒力。我们观察到，含尼古丁的EV增强了TIGR4生物膜，并改变了TIGR4基因的表达，这些基因主要参与代谢和应激反应。但是，在小鼠模型中，含尼古丁和不含尼古丁的EV均不会影响TIGR4毒力。