Figure 6. Sub-lethal induction of pyroptosis using transient opto-(h)caspase-1 activation in human keratinocytes.

The confluent monolayer of HaCaT cells was transiently stimulated with low-intensity (0.2 mW/cm²/pulse, three pulses) blue light at 3 min after the beginning of time lapse, and the data was acquired for 60 min. (A) Representative images of the whole illuminated population before (at 0 min) and after (60 min). DRAQ7 (turquoise) is a membrane-impermeable DNA-binding dye used to visualize pyroptotic membrane permeabilization. (B) Close-up images of cells displaying three types of fates: pyroptotic (top), sub-lethal (middle), and both pyroptotic and non-responding cells (bottom). Note the strong DRAQ7 signal and loss of cytoplasmic mCherry in pyroptotic cells and low DRAQ7 positivity in the sub-lethally activated cells.