Apoptosis signal-regulating kinase-1 promotes inflammasome priming in macrophages
© 2019 the American Physiological Society. previously showed that mice deficient in apo-ptosis signal-regulating kinase-1 (ASK1) were partially protected against ventilator-induced lung injury. Because ASK1 can promote both cell death and inflammation, we hypothesized that ASK1 activation regulates inflammasome-mediated inflammation. Mice deficient in ASK1 expression (ASK1 +/+ ) exhibited significantly less inflammation and lung injury (as measured by neutrophil infiltration, IL-6, and IL-1β) in response to treatment with inhaled lipopolysaccharide (LPS) compared with wild-type (WT) mice. To determine whether this proinflammatory response was mediated by ASK1, we investigated inflammasome-mediated responses to LPS in primary macrophages and bone marrow-derived macrophages (BMDMs) from WT and ASK1 +/+ mice, as well as the mouse alveolar macrophage cell line MH-S. Cells were treated with LPS alone for priming or LPS followed by ATP for activation. When macrophages were stimulated with LPS followed by ATP to activate the inflammasome, we found a significant increase in secreted IL-1β from WT cells compared with ASK1-deficient cells. LPS priming stimulated an increase in NOD-like receptor 3 (NLRP3) and pro-IL-1β in WT BMDMs, but expression of NLRP3 was significantly decreased in ASK1 +/+ BMDMs. Subsequent ATP treatment stimulated an increase in cleaved caspase-1 and IL-1β in WT BMDMs compared with ASK1 +/+ BMDMs. Similarly, treatment of MH-S cells with LPS + ATP caused an increase in both cleaved caspase-1 and IL-1β that was diminished by the ASK-1 inhibitor NQDI1. These results demonstrate, for the first time, that ASK1 promotes inflammasome priming.
Publication Source (Journal or Book title)
American Journal of Physiology - Lung Cellular and Molecular Physiology
Immanuel, C., Teng, B., Dong, B., Gordon, E., Kennedy, J., Luellen, C., Schwingshackl, A., Cormier, S., Fitzpatrick, E., & Waters, C. (2019). Apoptosis signal-regulating kinase-1 promotes inflammasome priming in macrophages. American Journal of Physiology - Lung Cellular and Molecular Physiology, 316 (3), L418-L427. https://doi.org/10.1152/ajplung.00199.2018