Reversible Opening of Intercellular Junctions of Intestinal Epithelial and Brain Endothelial Cells With Tight Junction Modulator Peptides  Alexandra Bocsik, Fruzsina R. Walter, Andrea Gyebrovszki, Lívia Fülöp, Ingolf Blasig, Sebastian Dabrowski, Ferenc Ötvös, András Tóth, Gábor Rákhely, Szilvia Veszelka, Monika Vastag, Piroska Szabó-Révész, Mária A. Deli  Journal of Pharmaceutical Sciences  Volume 105, Issue 2, Pages 754-765 (February 2016) DOI: 10.1016/j.xphs.2015.11.018 Copyright © 2016 American Pharmacists Association® Terms and Conditions

Figure 1 Cell viability assays after 1-hour treatment with tight junction modulator peptides. The toxicity of peptides on Caco-2 intestinal epithelial cells (a) and brain endothelial cells (b) was measured by MTT dye conversion assay. The effect of peptides on the impedance of epithelial (c) and brain endothelial (d) cell layers is shown as cell index. The MTT and cell index are given as percent of control (100% viability). Values are presented as means ± SD, n = 3-8. Statistical analysis: ANOVA followed by Dunnett’s test, p < 0.05 as compared with the control groups. Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Figure 2 Effects of modulator peptides on the resistance of Caco-2 epithelial (a) and brain endothelial (b) cell layers. White columns represent the effect of 1-h peptide treatment and gray columns show resistance after 24-h recovery. Data are presented as means ± SD, n = 3-6. Statistical analysis: ANOVA followed by Dunnett's test. Statistically significant differences are: *p < 0.05, compared to control group (Caco-2: 1309 ± 97 Ω × cm2; BBB: 314 ± 48 Ω × cm2); #p < 0.05 compared to control group value 24-h later (Caco-2: 1338 ± 53 Ω × cm2; BBB: 350 ± 60 Ω × cm2). Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Figure 3 Evaluation of barrier integrity on Caco-2 epithelial (a, b) and brain endothelial cell layers (c, d). Permeability for fluorescein (a, c) and for albumin (b, d) after 1-h treatment with modulator peptides and after 24-h recovery. White columns represent the effect of 1-hour peptide treatment and gray columns show permeability after 24-h recovery. Values of apparent permeability coefficients (Papp) in the respective control groups were fluorescein Papp in Caco-2: 0.20 ± 0.02 × 10−6 cm/s, and 0.30 ± 0.02 × 10−6 cm/s (a); albumin Papp in Caco-2: 0.26 ± 0.01 × 10−6 cm/s, and 0.27 ± 0.01 × 10−6 cm/s (b); fluorescein Papp in BBB model: 3.10 ± 0.26 × 10−6 cm/s and 3.42 ± 0.62 × 10−6 cm/s (c); albumin Papp in BBB model: 1.59 ± 0.23 × 10−6 cm/s and 1.61 ± 0.57 × 10−6 cm/s (d). Data are expressed in the % of control groups. Values are presented as means ± SD, n = 3-6. Statistical analysis: ANOVA followed by Dunnett's test and t test. Statistically significant differences were detected after treatment with peptides (p < 0.05) as compared with the control group (*) and compared with each peptide (#) after recovery. Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Figure 4 Effects of modulator peptides on junctional morphology of Caco-2 cells. Immunostaining for occludin and zonula occludens-1 (ZO-1) tight junction proteins, and β-catenin and E-cadherin adherens junction proteins after 1-h peptide treatment and 24-h recovery. Red color: immunostaining for ZO-1, β-catenin, and occludin. Green color: immunostaining for E-cadherin. Blue color: staining of cell nuclei. Bar = 25 μm. Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Figure 5 Effects of modulator peptides on junctional morphology of brain endothelial cells. Immunostaining for claudin-5 and ZO-1 tight junction proteins and β-catenin adherens junction protein after 1-h peptide treatment and 24-h recovery. Red color: immunostaining for ZO-1 and β-catenin. Green color: immunostaining for claudin-5. Blue color: staining of cell nuclei. Bar = 25 μm. Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Figure 6 Gene expression level of occludin and selected claudins in Caco-2 epithelial and brain endothelial cells. NE, not expressed; OCC, occludin. Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Figure 7 Affinity measurements of the peptide PN-159 to full-length claudins (a) and binding curve for claudin-5-YFP (b). The association was measured by microscale thermophoresis. Docking of PN-159 peptide to human claudin-1 (c) and human claudin-5 (d). Interacting residues are shown as sticks. Orange color: peptide PN-159; yellow color: β-strands; purple color: α-helices of claudins. Membrane surface is marked by a solid black line. Kd, dissociation constant; YFP, yellow fluorescent protein. Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Supplementary Figure 1 Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Supplementary Figure 2 Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Supplementary Figure 3 Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Supplementary Figure 4 Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Supplementary Figure 5 Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions

Supplementary Figure 6 Journal of Pharmaceutical Sciences 2016 105, 754-765DOI: (10.1016/j.xphs.2015.11.018) Copyright © 2016 American Pharmacists Association® Terms and Conditions