Vitamin D3 ameliorates nitrogen mustard-induced cutaneous inflammation by inactivating the NLRP3 inflammasome through the SIRT3-SOD2-mtROS signaling pathway.

Nitrogen mustard (NM) causes severe skin injury with an obvious inflammatory response, which is lack of effective and targeted therapies. Vitamin D3 (VD3) has excellent anti-inflammatory properties and is considered as a potential candidate for the treatment of NM-induced dermal toxicity; however, the underlying mechanisms are currently unclear. Cyclooxygenase-2 (COX2; a widely used marker of skin inflammation) plays a key role in NM-induced cutaneous inflammation. Herein, we initially confirmed that NM markedly promoted COX2 expression in vitro and in vivo. NM also increased NOD-like receptor family pyrin domain containing 3 (NLRP3) expression, caspase-1 activity, and interleukin-1β (IL-1β) release. Notably, treatment with a caspase-1 inhibitor (zYVAD-fmk), NLRP3 inhibitor (MCC950), and NLRP3 or caspase-1 siRNA attenuated NM-induced NLRP3 inflammasome activation, with subsequent suppression of COX2 expression and IL-1β release in keratinocytes. Meanwhile, NM increased mitochondrial reactive oxygen species (mtROS) and decreased manganese superoxide dismutase 2 (SOD2) and sirtuin 3 (SIRT3) activities. Mito-TEMPO (a mtROS scavenger) ameliorated NM-caused NLRP3 inflammasome activation in keratinocytes. Moreover, VD3 improved SIRT3 and SOD2 activities, decreased mtROS contents, inactivated the NLRP3 inflammasome, and attenuated cutaneous inflammation induced by NM in vitro and in vivo. The beneficial activity of VD3 against NM-triggered cutaneous inflammation was enhanced by the inhibitors of IL-1, mtROS, NLRP3, caspase-1, and NLRP3 or caspase-1 siRNAs, which was abolished in SIRT3 inhibitor or SIRT3 siRNA-treated keratinocytes and skins from SIRT3-/- mice. In conclusion, VD3 ameliorated NM-induced cutaneous inflammation by inactivating the NLRP3 inflammasome, which was partially mediated through the SIRT3-SOD2-mtROS signaling pathway.

Dong X ，He Y ，Ye F ，Zhao Y ，Cheng J ，Xiao J ，Yu W ，Zhao J ，Sai Y ，Dan G ，Chen M ，Zou Z ... -  《Clinical and Translational Medicine》

Trimethylamine-N-Oxide Induces Vascular Inflammation by Activating the NLRP3 Inflammasome Through the SIRT3-SOD2-mtROS Signaling Pathway.

Trimethylamine-N-oxide (TMAO) has recently been identified as a novel and independent risk factor for promoting atherosclerosis through inducing vascular inflammation. However, the exact mechanism is currently unclear. Studies have established a central role of nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome in the pathogenesis of vascular inflammation. Here, we examined the potential role of the NLRP3 inflammasome in TMAO-induced vascular inflammation in vitro and in vivo and the underlying mechanisms. Experiments using liquid chromatography-tandem mass spectrometry, Western blot, and fluorescent probes showed that TMAO-induced inflammation in human umbilical vein endothelial cells (HUVECs) and aortas from ApoE-/- mice. Moreover, TMAO promoted NLRP3 and activated caspase-1 p20 expression and caspase-1 activity in vitro and in vivo. Notably, a caspase-1 inhibitor (YVAD), an NLRP3 inhibitor (MCC950), as well as NLRP3 short interfering RNA attenuated TMAO-induced activation of the NLRP3 inflammasome, subsequently leading to suppression of inflammation in HUVECs. TMAO additionally stimulated reactive oxygen species (ROS) generation, in particular, mitochondrial ROS, while inhibiting manganese superoxide dismutase 2 (SOD2) activation and sirtuin 3 (SIRT3) expression in HUVECs and aortas from ApoE-/- mice. TMAO-induced endothelial NLRP3 inflammasome activation was ameliorated by the mitochondrial ROS scavenger Mito-TEMPO, or SIRT3 overexpression in HUVECs. Conversely, TMAO failed to further inhibit SOD2 and activate the NLRP3 inflammasome or induce inflammation in SIRT3 short interfering RNA-treated HUVECs and aortas from SIRT3-/- mice. TMAO promoted vascular inflammation by activating the NLRP3 inflammasome, and the NLRP3 inflammasome activation in part was mediated through inhibition of the SIRT3-SOD2-mitochondrial ROS signaling pathway.

Chen ML ，Zhu XH ，Ran L ，Lang HD ，Yi L ，Mi MT ... -  《Journal of the American Heart Association》

Prolonged fasting suppresses mitochondrial NLRP3 inflammasome assembly and activation via SIRT3-mediated activation of superoxide dismutase 2.

Twenty-four hours of fasting is known to blunt activation of the human NLRP3 inflammasome. This effect might be mediated by SIRT3 activation, controlling mitochondrial reactive oxygen species. To characterize the molecular underpinnings of this fasting effect, we comparatively analyzed the NLRP3 inflammasome response to nutrient deprivation in wild-type and SIRT3 knock-out mice. Consistent with previous findings for human NLRP3, prolonged fasting blunted the inflammasome in wild-type mice but not in SIRT3 knock-out mice. In SIRT3 knock-out bone marrow-derived macrophages, NLRP3 activation promoted excess cytosolic extrusion of mitochondrial DNA along with increased reactive oxygen species and reduced superoxide dismutase 2 (SOD2) activity. Interestingly, the negative regulatory effect of SIRT3 on NLRP3 was not due to transcriptional control or priming of canonical inflammasome components but, rather, occurred via SIRT3-mediated deacetylation of mitochondrial SOD2, leading to SOD2 activation. We also found that siRNA knockdown of SIRT3 or SOD2 increased NLRP3 supercomplex formation and activation. Moreover, overexpression of wild-type and constitutively active SOD2 similarly blunted inflammasome assembly and activation, effects that were abrogated by acetylation mimic-modified SOD2. Finally, in vivo administration of lipopolysaccharide increased liver injury and the levels of peritoneal macrophage cytokines, including IL-1β, in SIRT3 KO mice. These results support the emerging concept that enhancing mitochondrial resilience against damage-associated molecular patterns may play a pivotal role in preventing inflammation and that the anti-inflammatory effect of fasting-mimetic diets may be mediated, in part, through SIRT3-directed blunting of NLRP3 inflammasome assembly and activation.

Traba J ，Geiger SS ，Kwarteng-Siaw M ，Han K ，Ra OH ，Siegel RM ，Gius D ，Sack MN ... -  《-》

Heterozygous SOD2 deletion deteriorated chronic intermittent hypoxia-induced lung inflammation and vascular remodeling through mtROS-NLRP3 signaling pathway.

Song JQ ，Jiang LY ，Fu CP ，Wu X ，Liu ZL ，Xie L ，Wu XD ，Hao SY ，Li SQ ... -  《-》

Curcumin Ameliorates Age-Induced Tight Junction Impaired in Porcine Sertoli Cells by Inactivating the NLRP3 Inflammasome through the AMPK/SIRT3/SOD2/mtROS Signaling Pathway.

Blood-testis barrier (BTB) made of concomitant junction apparatus between Sertoli cells (SCs) is crucial for spermatogenesis. The tight junction (TJ) function is impaired in SCs with age, exhibiting an intimate relationship to testicular dysfunction induced by age. In this study, compared with those in young boars, TJ proteins (i.e., Occludin, ZO-1, and plus Claudin-11) were discovered to have reduced expressions in testes, and spermatogenesis ability declined in old boars. An in vitro age model for D-gal-treated porcine SCs was established, the performance of Curcumin as a natural antioxidant and anti-inflammatory compound in affecting the TJ function of SCs was appraised, and related molecular mechanisms were exploited. The results manifested that 40 g/L D-gal downregulated ZO-1, Claudin-11, and Occludin in terms of the expression in SCs, whereas Curcumin restored such expressions in D-gal-treated SCs. Using the AMPK and SIRT3 inhibiters demonstrated that activation of the AMPK/SIRT3 pathway was associated with Curcumin, which not only rescued the expression of ZO-1, Occludin, Claudin-11, and SOD2 but also inhibited the production of mtROS and ROS and the activation of NLRP3 inflammasome and release of IL-1β in D-gal-treated SCs. Furthermore, with mtROS scavenger (mito-TEMPO), NLRP3 inhibitor (MCC950) plus IL-1Ra treatment ameliorated D-gal-caused TJ protein decline in SCs. In vivo data also showed that Curcumin alleviated TJ impairment in murine testes, improved D-gal-triggered spermatogenesis ability, and inactivated the NLRP3 inflammasome by virtue of the AMPK/SIRT3/mtROS/SOD2 signal transduction pathway. Given the above findings, a novel mechanism where Curcumin modulates BTB function to improve spermatogenesis ability in age-related male reproductive disorder is characterized.

Xiao L ，Fang Z ，Wang Q ，Sheng X ，Qi X ，Xing K ，Guo Y ，Ni H ，Wang X ，Zhang Y ... -  《-》