Microparticulate P2X7 and GSDM-D mediated regulation of functional IL-1β release
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The pro-inflammatory cytokine IL-1β is a secreted protein that is cleaved by caspase-1 during inflammasome activation upon recognition of internal and external insults to cells. Purinergic receptor P2X7 has been described to be involved in the release pathway of bioactive mature IL-1β by activated immune cells. Microparticle (MP) shedding has also been recently recognized as a manner of cytokine IL-1β release. However, the understanding of purinergic receptor roles in the MP-mediated IL-1β release process is still rudimentary. Gasdermin-D (GSDM-D), a protein involved in pyroptosis and inflammasome activation, has been recently described to be involved in the release of microparticles by virtue of its pore-forming ability. Hence, our current work is aimed to study the role of P2X7 in regulating GSDM-D-mediated microparticles and thereby bioactive IL-1β release. We provide evidence that cleaved functional IL-1β release in microparticles upon LPS stimulation is regulated by GSDM-D and P2X7 in a two-step fashion. GSDM-D activation first regulates release of IL-1β and P2X7 into microparticles. Then, microparticulate active P2X7 receptor then regulates the release of bioactive IL-1β encapsulated in microparticles to be able to target other cells inducing IL-8. Using an ATP model of stimulation, we further demonstrated that extracellular ATP stimulation to IL-1β containing LPS microparticles induces release of its content, which when subjected to epithelial cells induced IL-8. This effect was blocked by P2X7 inhibitor, KN62, as well as by IL-1RA. Taken together, our findings demonstrate for the first time the synergistic critical roles of GSDM-D and purinergic receptors in the regulation of microparticulate bioactive IL-1β release and induction of target cell responses.
KeywordsP2X7 GSDM-D Microparticles IL-1β Monocytes Inflammasome
This work was supported by NIH RO1 HL24325 to Sarkar and NIH RO1GM108928 to Sarkar/Wewers.
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Conflicts of interest
Srabani Mitra declares that she has no conflict of interest.
Anasuya Sarkar declares that she has no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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