Dopamine mediates non-canonical NLRP3 inflammasome activation via caspase 1/4 in human monocyte-derived macrophages 2577

Description Dopaminergic immunomodulation is found in almost all immune cells, including macrophages, and a growing number of studies suggest it is an important component of innate immunity. Our published data show that dopamine increases the activation of nuclear factor kappa-B (NF-kB) in primary human monocyte-derived macrophages (hMDMs) and predisposes hMDMs to a more robust inflammatory response. These data expand on our previous studies, assessing dopamine-mediated changes in the magnitude and kinetics of several specific aspects of NLRP3 activation in hMDMs. We show that dopamine significantly increases the formation of PYCARD-positive specks, caspase activation, Gasdermin (GSDM) protein cleavage, and the release of inflammatory cytokines. These effects occur in a time-dependent manner, corresponding with the inflammasome activation process. Measuring inflammasome-associated caspase activity using flow cytometry and immunofluorescent staining shows that dopamine primes the activation of both caspases 1 and 4. We also found that in addition to increasing GSDM-D protein cleavage, dopamine increases the total expression of GSDM-B, which is closely linked to caspase 4 activity. Taken together, our findings indicate that both caspases 1 and 4 are critical regulators of dopamine-induced NLRP3 activation and that this may occur via a non-canonical activation pathway. These findings can introduce new therapeutic targets for conditions with altered dopamine levels, such as substance misuse.