Moores Rachel C, Brilha Sara, Schutgens Frans, Elkington Paul T, Friedland Jon S
Section of Infectious Diseases and Immunity, Imperial College London, London, UK.
Centre for Inflammation and Tissue Repair, Respiratory Medicine, University College London, London, UK.
Front Immunol. 2017 May 24;8:602. doi: 10.3389/fimmu.2017.00602. eCollection 2017.
In pulmonary tuberculosis (TB), the inflammatory immune response against (Mtb) is associated with tissue destruction and cavitation, which drives disease transmission, chronic lung disease, and mortality. Matrix metalloproteinase (MMP)-1 is a host enzyme critical for the development of cavitation. MMP expression has been shown to be epigenetically regulated in other inflammatory diseases, but the importance of such mechanisms in Mtb-associated induction of MMP-1 is unknown. We investigated the role of changes in histone acetylation in Mtb-induced MMP expression using inhibitors of histone deacetylases (HDACs) and histone acetyltransferases (HAT), HDAC siRNA, promoter-reporter constructs, and chromatin immunoprecipitation assays. Mtb infection decreased Class I HDAC gene expression by over 50% in primary human monocyte-derived macrophages but not in normal human bronchial epithelial cells (NHBEs). Non-selective inhibition of HDAC activity decreased MMP-1/-3 expression by Mtb-stimulated macrophages and NHBEs, while class I HDAC inhibition increased MMP-1 secretion by Mtb-stimulated NHBEs. MMP-3 expression, but not MMP-1, was downregulated by siRNA silencing of HDAC1. Inhibition of HAT activity also significantly decreased MMP-1/-3 secretion by Mtb-infected macrophages. The MMP-1 promoter region between -2,001 and -2,942 base pairs from the transcriptional start site was key in control of Mtb-driven MMP-1 gene expression. Histone H3 and H4 acetylation and RNA Pol II binding in the MMP-1 promoter region were increased in stimulated NHBEs. In summary, epigenetic modification of histone acetylation via HDAC and HAT activity has a key regulatory role in Mtb-dependent gene expression and secretion of MMP-1 and -3, enzymes which drive human immunopathology. Manipulation of epigenetic regulatory mechanisms may have potential as a host-directed therapy to improve outcomes in the era of rising TB drug resistance.
在肺结核（TB）中，针对结核分枝杆菌（Mtb）的炎症免疫反应与组织破坏和空洞形成有关，而这会导致疾病传播、慢性肺病和死亡。基质金属蛋白酶（MMP）-1是空洞形成过程中的一种关键宿主酶。在其他炎症性疾病中，MMP的表达已被证明受表观遗传调控，但这种机制在Mtb相关的MMP-1诱导中的重要性尚不清楚。我们使用组蛋白脱乙酰酶（HDAC）和组蛋白乙酰转移酶（HAT）抑制剂、HDAC小干扰RNA（siRNA）、启动子-报告基因构建体以及染色质免疫沉淀分析，研究了组蛋白乙酰化变化在Mtb诱导的MMP表达中的作用。Mtb感染使原代人单核细胞衍生巨噬细胞中的I类HDAC基因表达降低了50%以上，但在正常人支气管上皮细胞（NHBE）中未出现这种情况。HDAC活性的非选择性抑制降低了Mtb刺激的巨噬细胞和NHBE中MMP-1/-3的表达，而I类HDAC抑制增加了Mtb刺激的NHBE中MMP-1的分泌。HDAC1的siRNA沉默下调了MMP-3的表达，但未下调MMP-1的表达。HAT活性的抑制也显著降低了Mtb感染的巨噬细胞中MMP-1/-3的分泌。转录起始位点上游-2001至-2942碱基对之间的MMP-1启动子区域是控制Mtb驱动的MMP-1基因表达的关键。在受刺激的NHBE中，MMP-1启动子区域的组蛋白H3和H4乙酰化以及RNA聚合酶II结合增加。总之，通过HDAC和HAT活性进行的组蛋白乙酰化表观遗传修饰在Mtb依赖性基因表达以及驱动人类免疫病理学的酶MMP-1和-3的分泌中起关键调节作用。在结核病耐药性不断上升的时代，操纵表观遗传调控机制可能具有作为宿主导向疗法改善治疗结果的潜力。
