To Örebro University

Inflammasomes are multiprotein complexes that form in response to microbial and host-derived substances, leading to maturation and release of interleukin-1β and -18 and pyroptosis. The most extensively investigated inflammasome is the NLRP3 inflammasome, the formation and activation of which requires two distinct signals, an initial priming signal, and a second activation signal. Assessment of inflammasome activation is performed by measuring one or more readouts, such as ASC-speck formation, caspase-1 activation, cytokine release and LDH leakage from pyroptotic cells. The aims of this thesis are to examine the effects of inflammasome triggers on cell-morphological features in THP-1 cells, using a Cell Painting assay, and investigate the dynamics of inflammasome readouts.

The results demonstrate that biologically relevant morphological features, both common between triggers and specific to individual triggers, can be obtained in human THP-1 macrophages. Moreover, NLRP3 specific cellular features can be identified. Furthermore, our results suggest that readouts downstream of inflammasome formation are dynamically regulated in a trigger-dependent fashion. We demonstrate that, not only are temporal associations between readouts distinct with different triggers, but that populations of ASC-specks with different life times may be formed in response to the same trigger. In addition, utilizing several PDAC cell lines, we show that basal NLRP3 inflammasome capabilities are highly heterogenous between cell lines.

These results demonstrate the applicability of Cell Painting in immune cells and inflammasome research, and reveal a dynamic capability of the NLRP3 inflammasome that has previously, largely remained unexplored.