Exposure to hyperglycemic conditions, cigarette smoke extract and both combined impact expression and distribution of tight junction protein ZO-1. a 12 h exposure to CSE and HG + CSE increases ZO-1 expression in HCMEC/D3 as clearly shown by Western blot and immunofluorescence analysis of cell monolayers. However, protein distribution in the membrane was significantly altered. b By contrast to 12 h, 24 h exposure reversed the previous effect on ZO-1 expression which appeared to be down-regulated. As clearly shown by immunofluorescence analysis (both 12 and 24 h), there was a significant additive disruptive effect on ZO-1 distribution when HG and CSE were combined. n = 3–4 biological replicates. *p < 0.05, **p < 0.01, ***p < 0.001 vs. control; $
p < 0.05 vs. HG.