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Metformin alters Airway Epithelial Tight Junction Protein Abundance
Author(s) -
Garnett James,
Patkee Rgweda,
Weekes Alexina,
Baker Emma,
Baines Deborah
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.672.1
Subject(s) - occludin , paracellular transport , metformin , staphylococcus aureus , tight junction , respiratory epithelium , pseudomonas aeruginosa , western blot , chemistry , medicine , endocrinology , microbiology and biotechnology , biology , insulin , respiratory system , biochemistry , permeability (electromagnetism) , bacteria , genetics , membrane , gene
Glucose concentration in the airway surface liquid (ASL) is normally ~0.4mM. Raised blood glucose elevates ASL glucose (up to 4.0mM) which increases the risk of respiratory infection, particularly with methicillin‐resistant Staphylococcus aureus and Pseudomonas aeruginosa . Previously, in an H441/ S. aureus co‐culture model we showed that glucose diffused across the epithelium into the ASL via paracellular pathways and was utilised by the bacteria to support their growth. Treatment with metformin reduced paracellular permeability to glucose and supressed glucose‐induced S. aureus growth. In this study, we investigated the effect of metformin on airway epithelial tight junction protein abundance in epithelial/bacterial co‐cultures using western blot and immunocytochemical analysis. S. aureus (8325‐4) addition to the apical surface of H441 monolayers for 7 hours decreased E‐cadherin (p<0.001,n=13) and occludin abundance (p<0.05,n=5), but had no effect on claudin‐1 (p>0.05,n=3). Pre‐treatment of H441 monolayers with metformin (1 mM; 18 hours) prior to S. aureus addition, had no effect on E‐cadherin, but enhanced occludin abundance (p<0.05,n=5). P. aeruginosa (PA01) addition to the surface of Calu‐3 airway epithelial monolayers reduced transepithelial resistance (TEER) (from 669±27 to 489±20Ω.cm 2 ; p<0.05, n=5). Metformin attenuated this effect (551±16Ω.cm) and inhibited glucose‐induced bacterial growth (both p<0.05, n=4). P. aeruginosa had no effect on E‐cadherin or claudin‐1 abundance in Calu‐3 monolayers, but abolished occludin expression (p<0.0001, n=3). Metformin did not reverse the effect on occludin but increased claudin abundance in the presence and absence of P. aeruginosa (p<0.01, n=3)