NLRP3 inflammasome inhibition attenuates silica-induced epithelial to mesenchymal transition (EMT) in human bronchial epithelial cells.

Silicosis is an incurable and progressive lung disease characterized by chronic inflammation and fibroblasts accumulation. Studies have indicated a vital role for epithelial-mesenchymal transition (EMT) in fibroblasts accumulation. NLRP3 inflammasome is a critical mediator of inflammation in response to a wide range of stimuli (including silica particles), and plays an important role in many respiratory diseases. However, whether NLRP3 inflammasome regulates silica-induced EMT remains unknown. Our results showed that silica induced EMT in human bronchial epithelial cells (16HBE cells) in a dose- and time-dependent manner. Meanwhile, silica persistently activated NLRP3 inflammasome as indicated by continuously elevated extracellular levels of interleukin-1β (IL-1β) and IL-18. NLRP3 inflammasome inhibition by short hairpin RNA (shRNA)-mediated knockdown of NLRP3, selective inhibitor MCC950, and caspase-1 inhibitor Z-YVAD-FMK attenuated silica-induced EMT. Western blot analysis indicated that TAK1-MAPK-Snail/NF-κB pathway involved NLRP3 inflammasome-mediated EMT. Moreover, pirfenidone, a commercially and clinically available drug approved for treating idiopathic pulmonary fibrosis (IPF), effectively suppressed silica-induced EMT of 16HBE cells in line with NLRP3 inflammasome inhibition. Collectively, our results indicate that NLRP3 inflammasome is a promising target for blocking or retarding EMT-mediated fibrosis in pulmonary silicosis. On basis of this mechanism, pirfenidone might be a potential drug for the treatment of silicosis.

Li X ，Yan X ，Wang Y ，Wang J ，Zhou F ，Wang H ，Xie W ，Kong H ... -  《-》

Silica-induced NLRP3 inflammasome activation in vitro and in rat lungs.

Peeters PM ，Eurlings IM ，Perkins TN ，Wouters EF ，Schins RP ，Borm PJ ，Drommer W ，Reynaert NL ，Albrecht C ... -  《Particle and Fibre Toxicology》

Paricalcitol attenuates TGF-β1-induced phenotype transition of human peritoneal mesothelial cells (HPMCs) via modulation of oxidative stress and NLRP3 inflammasome.

Ko J ，Kang HJ ，Kim DA ，Ryu ES ，Yu M ，Lee H ，Lee HK ，Ryu HM ，Park SH ，Kim YL ，Kang DH ... -  《-》

Trichomonas vaginalis induces IL-1β production in a human prostate epithelial cell line by activating the NLRP3 inflammasome via reactive oxygen species and potassium ion efflux.

Trichomonas vaginalis is a sexually transmitted protozoan parasite that causes vaginitis in women, and urethritis and prostatitis in men. IL-1β is synthesized as immature pro-IL-1β, which is cleaved by activated caspase-1. Caspase-1 is, in turn, activated by a multi-protein complex known as an inflammasome. In this study, we investigated the inflammatory response of a prostate epithelial cell line (RWPE-1) to T. vaginalis and, specifically, the capacity of T. vaginalis to activate the NLRP3 inflammasome. RWPE-1 cells were stimulated by live T. vaginalis, and subsequent expression of pro-IL-1β, IL-1β, NLRP3, ASC and caspase-1 was determined by real-time PCR and Western blotting. IL-1β and caspase-1 production was also measured by ELISA. To evaluate the effects of NLRP3 and caspase-1 on IL-1β production, the activated RWPE-1 cells were transfected with small interfering RNAs to silence the NLRP3 and caspase-1 genes. Activation of the NLRP3 inflammasome was observed by fluorescence microscopy. Intracellular reactive oxygen species (ROS) were evaluated by spectrofluorometry. When RWPE-1 cells were stimulated with live T. vaginalis, the mRNA and protein expression of IL-1β, NLRP3, ASC, and caspase-1 increased. Moreover, silencing of NLRP3 and caspase-1 attenuated T. vaginalis-induced IL-1β secretion. The NADPH oxidase inhibitor DPI and high extracellular potassium ion suppressed the production of IL-1β, caspase-1, and the expression of NLRP3 and ASC proteins. The specific NF-κB inhibitor, Bay 11-7082, inhibited IL-1β production, and also inhibited the production of caspase-1, ASC and NLRP3 proteins. T. vaginalis induces the formation of the NLRP3 inflammasome in human prostate epithelial cells via ROS and potassium ion efflux, and this results in IL-1β production. This is the first evidence for activation of the NLRP3 inflammasome in the inflammatory response by prostate epithelial cells infected with T. vaginalis. Prostate 76:885-896, 2016. © 2016 Wiley Periodicals, Inc.

Gu NY ，Kim JH ，Han IH ，Im SJ ，Seo MY ，Chung YH ，Ryu JS ... -  《-》

Mechanisms that lead to the regulation of NLRP3 inflammasome expression and activation in human dental pulp fibroblasts.

The NLRP3 inflammasome plays an important role in the cellular defense against invading pathogens and is reported to be expressed in human dental pulp fibroblasts (HDPFs). However, the role of the NLRP3 inflammasome in HDPFs during pulpal infection and inflammation remains unclear. To elucidate the function of the NLRP3 inflammasome and the mechanisms that lead to its expression and activation in HDPFs. The test model used lipopolysaccharide (LPS) and adenosine triphosphate (ATP) to simulate an inflammatory environment. Lentiviral vectors encoding short hairpin RNAs were used to knock down NLRP3 and caspase-1 in HDPFs. Specific inhibitors were used to determine whether the toll-like receptor 4 (TLR4), myeloid differentiating factor 88 (MyD88), or nuclear factor-kappa B (NF-κB) pathways were involved in the regulation of NLRP3 expression. Reactive oxygen species (ROS) production was measured by fluorescent microscopy and flow cytometry using the total ROS/superoxide detection kit. Gene and protein expression were quantified by real-time polymerase chain reaction and Western blot, while cytokine release was measured by an enzyme-linked immunosorbent assay. LPS up-regulated NLRP3 and IL-1β expression while ATP induced the activation of caspase-1 and the release of IL-1β in LPS-primed HDPFs. The knockdown of NLRP3 or caspase-1 expression significantly inhibited IL-1β secretion. Pretreatment with a TLR4 inhibitor, a MyD88 inhibitory peptide, or an I Kappa B alpha (IκBα) phosphorylation inhibitor significantly inhibited LPS-induced NLRP3 and IL-1β expression. ATP potently promoted ROS generation in HDPFs; N-acetyl cysteine inhibited ROS production, caspase-1 activation and IL-1β secretion induced by ATP. Our results demonstrated that the NLRP3 inflammasome in HDPFs is crucial for IL-1β secretion in response to LPS plus ATP. LPS engaged the TLR4/MyD88/NF-κB pathway to enhance NLRP3 and pro-IL-1β expression in HDPFs. ATP promoted the generation of ROS and activated the NLRP3 inflammasome in a ROS-dependent manner.

Zhang A ，Wang P ，Ma X ，Yin X ，Li J ，Wang H ，Jiang W ，Jia Q ，Ni L ... -  《-》