Fig. 10. Cytosolic LPS induces pyroptosis but not LMP in both HT3B3-WT and HT3B3-KO cell lines.
a HT3B3-WT (blue) or HT3B3-KO (red) cells were subjected to nucleofection (nuc, +) in the absence (−) or presence (+) of 5 ug/ml LPS-EK (LPS), caspase-1 inhibitor, VX765, or lysosomal cysteine protease inhibitor, E64. An aliquot of cells were also not nucleofected (nuc, −). After 3 h, cells were stained with SG and Hoescht 33342 and imaged. Quantification: (# Sytox positive nuclei/# of blue nuclei) × 100. Means ± SD were compared using a two-tailed t-test (*P < 0.05). b Immunoblot of gasdermin D (GSDMD) and gasdermin E (GSDME) cleavage in THP1 cells treated with α-hemolysin (HlA); positive control. HT3B3-WT/HT3B3-KO were nucleofected with 0, 1, or 5 µg of LPS and left to recover for 1 h. Open arrowheads: full-length GSDMD and GSDME based on molecular mass. Black arrowheads: cleaved GSDMD. Dashed box: area contrast enhanced for clarity. Note, the positive control for GSDME cleavage is provided in Fig. S18b. c, d Flow cytometry analysis of HT3B3-WT/HT3B3-KO cells treated with a lysosomotropic agent, LLOMe (c) or 1 µg/ml LPS (d). Cells were stained with the lysosomotropic dye, acridine orange (Y-axis), and the cell viability dye, Sytox™ blue (X-axis). Lines indicate the threshold fluorescence levels (gate) to determine each quadrant. Numbers indicate cell percentage in each quadrant. e Schematic representation of each quadrant. Quadrant 1 (Q1) contained live cells positive for lysosomal staining (acridine orange positive, Sytox blue negative). Quadrant 2 (Q2) contained dead cells with positive lysosomal staining (acridine orange positive, Sytox blue positive). Quadrant 3 (Q3) contained dead cells negative for lysosomal staining (acridine orange negative, Sytox blue positive). Quadrant 4 (Q4) contained live cells negative for lysosomal staining (acridine orange negative, Sytox blue negative). Arrows indicate the timing of fluorescence loss for different cell death pathways. If the lysosomal loss occurred prior to plasma membrane permeabilization, then the percentage of cells will increase from Q1 to Q4 to Q3 over time. If the lysosomal loss occurred after plasma membrane loss, then the percentage of cells will increase from Q1 to Q2 to Q3 over time. f, g Graphical representation of the average of three separate experiments indicating the percentage of cells treated with LLOMe (f) or nucleofected LPS (g) in HT3B3-WT (blue) and HT3B3-KO (red) cells. Error bars represent means ± SD. Uncropped immunoblots can be found in Supplementary Fig. 21.