Metformin alters human host responses to Mycobacterium tuberculosis in-vitro and in healthy human subjects [PBMC RNA-Seq]

Metformin, the most widely administered diabetes drug, has been proposed as a candidate for host directed therapy for tuberculosis although very little is known about its effects on human host responses to Mycobacterium tuberculosis. When added in vitro to PBMCs isolated from healthy non-diabetic volunteers, metformin increased glycolysis, inhibited the mTOR targets, strongly reduced M. tuberculosis induced production of TNF-alpha (-58%), IFN-gamma (-47%) and IL-beta (-20%), while increasing phagocytosis. In healthy subjects, in vivo metformin intake induced significant transcriptional changes in whole blood and isolated PBMCs, with substantial down-regulation of genes related to inflammation and the type 1 interferon response. Metformin intake also increased monocyte phagocytosis (by 1.5 to 2 fold) and ROS production (+20%). These results show that metformin in humans has a range of potentially beneficial effects on cellular metabolism, immune function and gene-transcriptional level, that affect innate host responses to M. tuberculosis. This underlines the importance of cellular metabolism for host immunity and supports a role for metformin as host-directed therapy for tuberculosis. Peripheral Mononuclear Cells taken from 11 healthy donors, prior to administration of metformin and after 5 days of metformin. Samples were stimulated with Mycobacterium tuberculosis lysate or cultured unstimulated for 4 hours. Total 88 samples, with 11 clinical replicates.

二甲双胍（Metformin）是目前临床应用最广泛的糖尿病治疗药物，尽管其对人体宿主抗结核分枝杆菌（Mycobacterium tuberculosis）应答的调控效应尚未得到充分阐明，但已有研究将其作为结核病宿主导向治疗（host-directed therapy）的候选药物。当在体外将二甲双胍添加至从健康非糖尿病志愿者体内分离的外周血单个核细胞（Peripheral Mononuclear Cells, PBMC）中时，其可促进糖酵解过程、抑制雷帕霉素靶蛋白（mTOR）的下游靶点，并显著降低结核分枝杆菌诱导的肿瘤坏死因子-α（TNF-α，下降58%）、干扰素-γ（IFN-γ，下降47%）及白细胞介素-β（IL-β，下降20%）的产生，同时增强吞噬活性。在健康受试者体内，口服二甲双胍可使全血及分离得到的外周血单个核细胞发生显著的转录水平改变，其中与炎症及I型干扰素应答相关的基因均出现明显下调。口服二甲双胍还可使单核细胞吞噬活性提升1.5至2倍，同时使活性氧（Reactive Oxygen Species, ROS）生成量增加20%。上述研究结果表明，二甲双胍可从细胞代谢、免疫功能及基因转录水平对人体产生一系列潜在有益效应，进而调控宿主对结核分枝杆菌的固有免疫应答。该研究凸显了细胞代谢在宿主免疫中的重要性，同时进一步支持二甲双胍作为结核病宿主导向治疗候选药物的应用价值。本数据集的样本取自11名健康志愿者，分别采集其服用二甲双胍前及连续服用二甲双胍5天后的外周血单个核细胞。所有样本均经结核分枝杆菌裂解液刺激，或在无刺激条件下培养4小时，最终共计获得88份样本，包含11份临床重复样本。