Despite the increasing commercial use of nanoparticles, little is known about their effects on placental inflammation and pregnancy complications. In this study, nanosilica (NS) particles upregulated the inflammasome component nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) and induced placental inflammation and reactive oxygen species (ROS) generation, resulting in pregnancy complications. Furthermore, NS-induced pregnancy complications were markedly improved in Nlrp3^−/− mice but not in component apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC)-deficient (Asc^−/−) mice, indicating the independence of NLRP3 inflammasomes. Pregnancy complications in Nlrp3^−/− and Asc^−/− mice phenotypes were dependent on the balance between interleukin (IL)-1α and IL-10. NS-induced pregnancy complications were completely prevented by either inhibition of ROS generation or forced expression of IL-10. Our findings provide important information about NS-induced placental inflammation and pregnancy complications and the novel pathophysiological roles of NLRP3 and ASC in pregnancy.

CD4⁺ Th cells play crucial roles in orchestrating immune responses against pathogenic microbes, after differentiating into effector subsets. Recent research has revealed the importance of IFN-γ and IL-17 double-producing CD4⁺ Th cells, termed Th17/Th1 cells, in the induction of autoimmune and inflammatory diseases. In addition, Th17/Th1 cells are involved in the regulation of infection caused by the intracellular bacterium Mycobacterium tuberculosis in humans. However, the precise mechanism of Th17/Th1 induction during pathogen infection is unclear. In this study, we showed that the inflammasome and Fas-dependent IL-1β induces Th17/Th1 cells in mice, in response to infection with the pathogenic intracellular bacterium Listeria monocytogenes. In the spleens of infected wild-type mice, Th17/Th1 cells were induced, and expressed T-bet and Rorγt. In Pycard^−/− mice, which lack the adaptor molecule of the inflammasome (apoptosis-associated speck-like protein containing a caspase recruitment domain), Th17/Th1 induction was abolished. In addition, the Fas-mediated IL-1β production was required for Th17/Th1 induction during bacterial infection: Th17/Th1 induction was abolished in Fas^−/− mice, whereas supplementation with recombinant IL-1β restored Th17/Th1 induction via IL-1 receptor 1 (IL-1R1), and rescued the mortality of Fas^−/− mice infected with Listeria. IL-1R1, but not apoptosis-associated speck-like protein containing a caspase recruitment domain or Fas on T cells, was required for Th17/Th1 induction, indicating that IL-1β stimulates IL-1R1 on T cells for Th17/Th1 induction. These results indicate that IL-1β, produced by the inflammasome and Fas-dependent mechanisms, contributes cooperatively to the Th17/Th1 induction during bacterial infection. This study provides a deeper understanding of the molecular mechanisms underlying Th17/Th1 induction during pathogenic microbial infections in vivo.

Hypertension causes vascular complications, such as stroke, cardiovascular disease, and chronic kidney disease (CKD). The relationship between endothelial dysfunction and progression of kidney disease is well known. However, the relationship between the eNOS–NO pathway and chronic inflammation, which is a common pathway for the progression of kidney disease, remains unexplored. We performed in vivo experiments to determine the role of the eNOS–NO pathway by using eNOS-deficient mice in a hypertensive kidney disease model. All mice were unilateral nephrectomized (Nx). One week after Nx, the mice were randomly divided into two groups: the aldosterone infusion groups and the vehicle groups. All mice also received a 1% NaCl solution instead of drinking water. The aldosterone infusion groups were treated with hydralazine to correct blood pressure differences. After four weeks of drug administration, all mice were euthanized, and blood and kidney tissue samples were collected. In the results, NLRP3 inflammasome activation was elevated in the kidneys of the eNOS-deficient mice, and tubulointerstitial fibrosis was accelerated. Suppression of inflammasome activation by knocking out ASC prevented tubulointerstitial injury in the eNOS knockout mice, indicating that the eNOS–NO pathway is involved in the development of kidney dysfunction through acceleration of NLRP3 inflammasome in macrophages. We revealed that endothelial function, particularly the eNOS–NO pathway, attenuates the progression of renal tubulointerstitial injury via suppression of inflammasome activation. Clinically, patients who develop vascular endothelial dysfunction have lifestyle diseases, such as hypertension or diabetes, and are known to be at risk for CKD. Our study suggests that the eNOS–NO pathway could be a therapeutic target for the treatment of chronic kidney disease associated with endothelial dysfunction.

The apoptosis-associated speck-like protein containing a caspase recruit domain (ASC) is involved in apoptosis and innate immunity and is a major adaptor molecule responsible for procaspase-1 activation. ASC mRNA is encoded by three exons: exons 1 and 3 encode a pyrin domain (PYD) and caspase recruit domain (CARD), respectively, and exon 2 encodes a proline and glycine-rich (PGR) domain. Here, we identified a variant ASC protein (vASC) lacking the PGR domain that was smaller than full length ASC (fASC) derived from fully transcribed mRNA and searched for differences in biochemical and biological nature. Both fASC and vASC were found to activate procaspase-1 to a similar degree, but the efficiency of IL-1βexcretion was significantly higher for vASC. There was also a marked structural difference observed in the fibrous aggregates formed by fASC and vASC. These results suggest that although the PGR domain is dispensable for procaspase-1 activation, it plays an important role in the regulation of the molecular structure and activity of ASC.