Fig. 7. High steady-state NF-ĸB signaling increases the responder percentage.

a WT monolayers were treated with indicated stimulus four times over a 9-day period. Concentrations of inputs were: Poly(I:C) 1 µg/ml, TNFα 100 ng/ml, Flagellin 1 µg/ml, Pam3CSK4 1 µg/ml, IL-1β 100 ng/ml, IFNγ 5 µ/ml, and TGFβ 5 ng/ml. Error bars represent six technical replicates with n > 1000 cells per replicate. Two-sample t test *p < 0.05 and ***p < 0.001. b Schematic indicating experimental workflow for data in panel c. Monolayers were stimulated with inputs every 2 days and washed or not after 30 min. After the last stimulation (day 8), all monolayers were washed for 24 h before determining responder fraction with Pam3CSK4 as in Fig. 2a. c Monolayers treated as detailed in panel b, input concentrations as in panel a. Two biological replicates, five technical replicates for each condition, ***p < 0.001; two-sample t-test. d Summary of model. Epithelial tissue contains cells that are all-or-nothing responsive or non-responsive to lipopeptide agonists. Response status is defined by TLR2 expression, which is controlled by epigenetic modifications to the TLR2 promoter. At steady state the fraction of responders is low; however, high inflammatory signaling involving innate immune cell types (e.g. dendritic cells, macrophages), leads to changes in the rate of epigenetic switching that increase the fraction of responsive cells in the tissue.