Center for Experimental and Molecular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands; Amsterdam Infection & Immunity Institute, Amsterdam, the Netherlands.
Center for Experimental and Molecular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands; Amsterdam Infection & Immunity Institute, Amsterdam, the Netherlands.
Biochim Biophys Acta Mol Basis Dis. 2022 Nov 1;1868(11):166519. doi: 10.1016/j.bbadis.2022.166519. Epub 2022 Aug 12.
Community-acquired pneumonia (CAP) is responsible for a high morbidity and mortality worldwide. Monocytes are essential for pathogen recognition and the initiation of an innate immune response. Immune cells induce intracellular glycolysis upon activation to support several functions.
To obtain insight in the metabolic profile of blood monocytes during CAP, with a focus on glycolysis and branching metabolic pathways, and to determine a possible association between intracellular metabolite levels and monocyte function.
Monocytes were isolated from blood of patients with CAP within 24 h of hospital admission and from control subjects matched for age, sex and chronic comorbidities. Changes in glycolysis, oxidative phosphorylation (OXPHOS), tricarboxylic acid (TCA) cycle and the pentose phosphate pathway were investigated through RNA sequencing and metabolomics measurements. Monocytes were stimulated ex vivo with lipopolysaccharide (LPS) to determine their capacity to produce tumor necrosis factor (TNF), interleukin (IL)-1β and IL-10.
50 patients with CAP and 25 non-infectious control subjects were studied. When compared with control monocytes, monocytes from patients showed upregulation of many genes involved in glycolysis, including PKM, the gene encoding pyruvate kinase, the rate limiting enzyme for pyruvate production. Gene set enrichment analysis of OXPHOS, the TCA cycle and the pentose phosphate pathway did not reveal differences between monocytes from patients and controls. Patients' monocytes had elevated intracellular levels of pyruvate and the TCA cycle intermediate α-ketoglutarate. Monocytes from patients were less capable of producing cytokines upon LPS stimulation. Intracellular pyruvate (but not α-ketoglutarate) concentrations positively correlated with IL-1β and IL-10 levels released by patients' (but not control) monocytes upon exposure to LPS.
These results suggest that elevated intracellular pyruvate levels may partially maintain cytokine production capacity of hyporesponsive monocytes from patients with CAP.
社区获得性肺炎（CAP）在全球范围内导致高发病率和死亡率。单核细胞对于病原体识别和先天免疫反应的启动至关重要。免疫细胞在激活后诱导细胞内糖酵解以支持多种功能。
了解 CAP 患者血液单核细胞的代谢特征，重点关注糖酵解和分支代谢途径，并确定细胞内代谢物水平与单核细胞功能之间的可能关联。
在入院后 24 小时内从 CAP 患者和年龄、性别和慢性合并症相匹配的对照者的血液中分离单核细胞。通过 RNA 测序和代谢组学测量研究糖酵解、氧化磷酸化（OXPHOS）、三羧酸（TCA）循环和磷酸戊糖途径的变化。体外用脂多糖（LPS）刺激单核细胞以确定其产生肿瘤坏死因子（TNF）、白细胞介素（IL）-1β和 IL-10 的能力。
研究了 50 例 CAP 患者和 25 例非感染性对照者。与对照单核细胞相比，患者单核细胞中许多参与糖酵解的基因上调，包括 PKM，即编码丙酮酸激酶的基因，丙酮酸产生的限速酶。OXPHOS、TCA 循环和磷酸戊糖途径的基因集富集分析未显示患者和对照者单核细胞之间的差异。患者单核细胞的细胞内丙酮酸和 TCA 循环中间产物α-酮戊二酸水平升高。LPS 刺激后，患者单核细胞产生细胞因子的能力降低。患者（而非对照）单核细胞在 LPS 刺激下释放的细胞内丙酮酸（而非α-酮戊二酸）浓度与 IL-1β 和 IL-10 水平呈正相关。
这些结果表明，细胞内丙酮酸水平升高可能部分维持 CAP 患者低反应性单核细胞的细胞因子产生能力。
