TLR4-upregulated IL-1β and IL-1RI promote alveolar macrophage pyroptosis and lung inflammation through an autocrine mechanism

X He, Y Qian, Z Li, EK Fan, Y Li, L Wu, TR Billiar… - Scientific reports, 2016 - nature.com
X He, Y Qian, Z Li, EK Fan, Y Li, L Wu, TR Billiar, MA Wilson, X Shi, J Fan
Scientific reports, 2016nature.com
Acute lung injury (ALI) is a major component of multiple organ dysfunction syndrome
(MODS) following pulmonary infection. Alveolar macrophages (AM) are at the center of the
pathogenesis of the development of ALI. Interleukin-1β (IL-1β) is one of the key pro-
inflammatory mediators and its maturation is tightly controlled by the formation and activation
of the inflammasome. The biological effects of IL-1β are mediated through IL-1 receptor (IL-
1R). In this study, we investigated the influence of LPS-induced IL-1β release and IL-1RI …
Abstract
Acute lung injury (ALI) is a major component of multiple organ dysfunction syndrome (MODS) following pulmonary infection. Alveolar macrophages (AM) are at the center of the pathogenesis of the development of ALI. Interleukin-1β (IL-1β) is one of the key pro-inflammatory mediators and its maturation is tightly controlled by the formation and activation of the inflammasome. The biological effects of IL-1β are mediated through IL-1 receptor (IL-1R). In this study, we investigated the influence of LPS-induced IL-1β release and IL-1RI upregulation on the development of lung inflammation. We demonstrated that in AM, LPS-TLR4 signaling not only activates Nlrp3 inflammasome activation and subsequent release of IL-1β, but also up-regulates IL-1RI expression on AM surface through MyD88 and NF-κB dependent signaling. The upregulated IL-1RI, therefore, sensitizes AM to IL-1β and results in pyroptosome formation, which in turn leads to AM pyroptosis, a type of caspase-1-dependent inflammatory cell death. We further showed that AM pyroptosis exaggerates lung inflammation. The present study demonstrates a novel mechanism underlying LPS-induced innate immunity; that is, a secondary upregulation of IL-1β-IL-1RI signaling is responsible for AM pyroptosis and augmented lung injury in response to LPS.
nature.com