Patkee Wishwanath R A, Carr Georgina, Baker Emma H, Baines Deborah L, Garnett James P
Institute for Infection and Immunity, St George's, University of London, London, UK.
Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, UK.
J Cell Mol Med. 2016 Apr;20(4):758-64. doi: 10.1111/jcmm.12784. Epub 2016 Feb 2.
Lung disease and elevation of blood glucose are associated with increased glucose concentration in the airway surface liquid (ASL). Raised ASL glucose is associated with increased susceptibility to infection by respiratory pathogens including Staphylococcus aureus and Pseudomonas aeruginosa. We have previously shown that the anti-diabetes drug, metformin, reduces glucose-induced S. aureus growth across in vitro airway epithelial cultures. The aim of this study was to investigate whether metformin has the potential to reduce glucose-induced P. aeruginosa infections across airway epithelial (Calu-3) cultures by limiting glucose permeability. We also explored the effect of P. aeruginosa and metformin on airway epithelial barrier function by investigating changes in tight junction protein abundance. Apical P. aeruginosa growth increased with basolateral glucose concentration, reduced transepithelial electrical resistance (TEER) and increased paracellular glucose flux. Metformin pre-treatment of the epithelium inhibited the glucose-induced growth of P. aeruginosa, increased TEER and decreased glucose flux. Similar effects on bacterial growth and TEER were observed with the AMP activated protein kinase agonist, 5-aminoimidazole-4-carboxamide ribonucleotide. Interestingly, metformin was able to prevent the P. aeruginosa-induced reduction in the abundance of tight junction proteins, claudin-1 and occludin. Our study highlights the potential of metformin to reduce hyperglycaemia-induced P. aeruginosa growth through airway epithelial tight junction modulation, and that claudin-1 and occludin could be important targets to regulate glucose permeability across airway epithelia and supress bacterial growth. Further investigation into the mechanisms regulating metformin and P. aeruginosa action on airway epithelial tight junctions could yield new therapeutic targets to prevent/suppress hyperglycaemia-induced respiratory infections, avoiding the use of antibiotics.
肺部疾病和血糖升高与气道表面液体（ASL）中葡萄糖浓度增加有关。ASL葡萄糖升高与包括金黄色葡萄球菌和铜绿假单胞菌在内的呼吸道病原体感染易感性增加有关。我们之前已经表明，抗糖尿病药物二甲双胍可降低体外气道上皮培养物中葡萄糖诱导的金黄色葡萄球菌生长。本研究的目的是调查二甲双胍是否有可能通过限制葡萄糖通透性来减少气道上皮（Calu-3）培养物中葡萄糖诱导的铜绿假单胞菌感染。我们还通过研究紧密连接蛋白丰度的变化，探讨了铜绿假单胞菌和二甲双胍对气道上皮屏障功能的影响。顶端铜绿假单胞菌生长随基底外侧葡萄糖浓度增加而增加，跨上皮电阻（TEER）降低，细胞旁葡萄糖通量增加。上皮细胞的二甲双胍预处理抑制了葡萄糖诱导的铜绿假单胞菌生长，增加了TEER并降低了葡萄糖通量。用AMP活化蛋白激酶激动剂5-氨基咪唑-4-甲酰胺核糖核苷酸观察到对细菌生长和TEER有类似影响。有趣的是，二甲双胍能够防止铜绿假单胞菌诱导的紧密连接蛋白claudin-1和occludin丰度降低。我们的研究强调了二甲双胍通过气道上皮紧密连接调节来减少高血糖诱导的铜绿假单胞菌生长的潜力，并且claudin-1和occludin可能是调节气道上皮葡萄糖通透性和抑制细菌生长的重要靶点。进一步研究调节二甲双胍和铜绿假单胞菌对气道上皮紧密连接作用的机制，可能会产生新的治疗靶点，以预防/抑制高血糖诱导的呼吸道感染，避免使用抗生素。
