No abstract

Endoplasmic reticulum (ER)‐Golgi vesicle trafficking plays a pivotal role in the conventional secretory pathway of many cytokines; however, the precise release mechanism of a major inflammasome mediator, IL‐1β, is not thought to follow the conventional ER‐Golgi route and remains elusive. Here, we found that perturbation of ER‐Golgi trafficking by brefeldin A (BFA) treatment attenuated nucleotide‐binding oligomerization domain‐like receptor family, pyrin–domain–containing 3 (NLRP3) inflammasome activation in mouse bone marrow–derived macrophages (BMDMs). BFA treatment inhibited NLRP3‐mediated inflammasome assembly and caspase‐1 activation but did not block IL‐1β secretion from BMDMs following BFA administration after NLRP3 inflammasome activation. Consistently, short‐hairpin RNA–dependent knockdown of BFA‐inhibited guanine nucleotide‐exchange protein 1 (BIG1), a molecular target of BFA and an initiator of Golgi‐specific vesicle trafficking, abolished NLRP3‐dependent apoptosis‐associated speck‐like protein containing a caspase‐recruitment domain oligomerization and caspase‐1 activation in BMDMs. Similarly, knockdown of Golgi‐specific BFA‐resistance guanine nucleotide exchange factor 1, another target of BFA, clearly attenuated NLRP3‐mediated caspase‐1 activation in BMDMs. Mechanistically, inhibition of BIGl‐mediated vesicle trafficking did not impair NLRP3‐activating signal 2‐promoted events, such as potassium efflux and mitochondrial rearrangement, but caused significant impairment of signal 1‐triggered priming steps, including NF‐κB–mediated pathways. These data suggest that BFA‐targeted vesicle trafficking at the Golgi contributes to activation of the NLRP3 inflammasome signaling.—Hong, S., Hwang, I., Gim, E., Yang, J., Park, S., Yoon, S.‐H., Lee, W.‐W., Yu, J.‐W. Brefeldin A–sensitive ER‐Golgi vesicle trafficking contributes to NLRP3‐dependent caspase‐1 activation. FASEB J. 33, 4547–4558 (2019). http://www.fasebj.org

Aberrant inflammasome activation contributes to various chronic inflammatory diseases; however, pyroptosis of inflammasome-active cells promptly terminates local inflammasome response. Molecular mechanisms underlying prolonged inflammasome signaling thus require further elucidation. Here, we report that neutrophil-specific resistance to pyroptosis and NLRP3 desensitization can facilitate sustained inflammasome response and interleukin-1β secretion. Unlike macrophages, inflammasome-activated neutrophils did not undergo pyroptosis, indicated by using in vitro cell-based assay and in vivo mouse model. Intriguingly, danger-associated molecular patterns (DAMP)-rich milieu in the inflammatory region significantly abrogated NLRP3-activating potential of macrophages, but not of neutrophils. This macrophage-specific NLRP3 desensitization was associated with DAMP-induced mitochondrial depolarization that was not observed in neutrophils due to a lack of SARM1 expression. Indeed, valinomycin-induced compulsory mitochondrial depolarization in neutrophils restored inflammasome-dependent cell death and ATP-induced NLRP3 desensitization in neutrophils. Alongside prolonged inflammasome-activating potential, neutrophils predominantly secreted interleukin-1β rather than other proinflammatory cytokines upon NLRP3 stimulation. Furthermore, inflammasome-activated neutrophils did not trigger efferocytosis-mediated M2 macrophage polarization essential for the initiation of inflammation resolution. Taken together, our results indicate that neutrophils can prolong inflammasome response via mitochondria-dependent resistance to NLRP3 desensitization and function as major interleukin-1β-secreting cells in DAMP-rich inflammatory region.

No abstract

For high-speed digital circuits a novel elevated-CPW (ECPW) structure with low loss and low dispersion is ,proposed and the performances are well compared with the theoretical prediction. The ECPW is designed with the aid of time domain fullwave FDTD technique and is fabricated using conventional thick-film MEMS processing. Proposed structure reveal at least lOdB lower insertion loss compared to conventional CPW geometries and effective permittivity is 4 to 6 times smaller than that of conventional CPW. Characteristic impedances and effective permittivities are given for various geometrical parameters.