Fig. 7: Cytokines induce lysosomal membrane permeabilization and Cathepsin B leakage

a, b Acridine staining in INS-1E cells treated or not (ctrl) with IL-1β + IFNγ (cyt) for 8 h, chloroquine (CQ) or bafilomycin (Baf) or torin1 for 3 h, or thapsigargin (Tg) for 5 h. a Representative live INS-1E cell imaging of acridine staining (red + green signal overlay). Insets are three-fold magnifications. b Quantitative assessment of red (650 nm) over green (525 nm) acridine fluorescent signal as assessed in live cells using a fluorescent microplate reader. c, d Cathepsin B activity assay using cresyl violet fluorescence (628 nm) in live INS-1E cells treated or not (ctrl) with IL-1β + IFNγ (cyt) for 8 h, or chloroquine (CQ), bafilomycin (Baf), or torin1 for 3 h. c Fluorescence (628 nm) signal as assessed by mutiplate reader. d Representative images; full arrows point cells with cathepsin leakage, empty arrows point cells with accumulation of large dots of Cathepsin B activity; scale bar represents 10 µm. e Prevalence of apoptosis was evaluated by HO-PI staining in INS-1E cells treated or not (ctrl) for 16 h with IL-1β + IFNγ or torin1, alone or in combination with Cathepsin B Inhibitor II or Cathepsin Inhibitor III (Cati II or III; 10 µM). **P < 0.01, ***P < 0.001 vs. ctrl; °P < 0.05, °°°P < 0.001 vs. cyt as determined by one-way ANOVA with Tukey’s correction