Melatonin attenuates LPS-induced pyroptosis in acute lung injury by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis.

Acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS) is featured by intensive inflammatory responses and oxidative stress, which lead to cytokine storms and pyroptosis. Here, we aimed to investigate whether melatonin was capable of alleviating LPS-induced ALI via activating the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling axis and inhibiting pyroptosis. Mice were injected with melatonin (30 mg/kg) intraperitoneally for consecutive five days before LPS instillation intratracheally, and human alveolar epithelial cell (AECⅡ) A549 cell lines and murine macrophages Raw264.7 cell lines were pretreated with melatonin (400 μM) before LPS (10 μg/ml) stimulation. The result demonstrated that LPS induced obvious lung injury characterized by alveolar damage, neutrophil infiltration and lung edema as well as the reduction of the survival rate of mice, which were totally reversed by melatonin pretreatment. Mechanistically, melatonin pretreatment activated nuclear factor erythroid2-related factor (Nrf) 2 signaling, subsequently, drove antioxidant pathways including significant increases in the expression of Nrf2, HO-1, NQO1, Mn-SOD and Catalase in vivo and in vitro. Simultaneously, melatonin inhibited ROS and MDA overproduction, iNOS expression as well as TNF-α and IL-1β expression and release. Furthermore, melatonin inhibited LPS-induced pyroptosis by reversing the overexpression of NLRP3, Caspase-1, IL-1β, IL-18 and GSDMD-N, as well as LDH release and TUNEL-positive cells in A549 cells and Raw264.7 cells. Overall, the current study suggests that melatonin exerts protective roles on LPS-induced ALI and pyroptosis by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis.

Kang JY ，Xu MM ，Sun Y ，Ding ZX ，Wei YY ，Zhang DW ，Wang YG ，Shen JL ，Wu HM ，Fei GH ... -  《-》

Fudosteine attenuates acute lung injury in septic mice by inhibiting pyroptosis via the TXNIP/NLRP3/GSDMD pathway.

There is a dearth of effective pharmacotherapies for sepsis-induced acute lung injury/acute respiratory distress syndrome (ALI/ARDS) to which oxidative stress and excessive inflammation are major contributors. We hypothesized that fudosteine, a cysteine derivative, may protect against sepsis-induced ALI/ARDS given its anti-oxidant capacity. This study aimed to investigate the effects and mechanisms of fudosteine in a mouse model of sepsis-induced ALI. Sepsis was induced by cecal ligation and puncture (CLP). The intragastrical administration of fudosteine (25 mg/kg, 50 mg/kg, and 100 mg/kg) dose-dependently decreased proinflammatory cytokine levels in bronchoalveolar lavage fluid (BALF) and serum and reduced BALF/serum albumin and lung wet/dry weight ratios in septic mice. The lung injury score was significantly lowered by fudosteine [e.g., 0.18 ± 0.03 (100 mg/kg) vs. 0.42 ± 0.03 (CLP), P < 0.0001]. Fudosteine also reduced the biomarkers of lung epithelial injury in BALF and markedly improved oxidative stress indicators in lung tissues [e.g., malondialdehyde: 337.70 ± 23.78 (100 mg/kg) vs. 686.40 ± 28.36 (CLP) nmol/mg protein, P < 0.0001]. Lung tissue transcriptomics analyses revealed suppressed inflammatory responses and oxidative stress with fudosteine and the involvement of the inflammasome and pyroptosis pathways. Western blot analyses indicated that fudosteine inhibited the sepsis-induced activation of gasdermin D (GSDMD) and caspase-1 and the upregulation of thioredoxin-interacting protein (TXNIP), nucleotide-binding domain, leucine-rich repeat-containing receptor, pyrin domain-containing-3 (NLRP3), and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC). Fudosteine therefore protects against sepsis-induced ALI in mice, and the inhibition of pyroptosis via the TXNIP/NLRP3/GSDMD pathway may be an underlying mechanism.

He G ，Chen K ，Wang H ，Li X ，Li W ，Liu L ，Chen J ，Yang D ，Hu J ，Xu D ，Wen F ，Wang T ... -  《-》

Maresin 1 protects against lipopolysaccharide/d-galactosamine-induced acute liver injury by inhibiting macrophage pyroptosis and inflammatory response.

Acute liver injury (ALI) caused by sepsis is a fearful disease with high mortality and poor prognosis. This study aimed to explore the roles and mechanism of Maresin 1 (MaR1) in lipopolysaccharide/d-galactosamine (LPS/D-GalN)-induced ALI. We established an ALI mouse model induced by LPS/D-GalN. Each group was treated with or without LPS/D-GalN or MaR1. For the vitro experiments, RAW264.7, NCTC1469 cells, and bone marrow-derived macrophages (BMDMs) were stimulated with LPS. The effects of MaR1 on the reactive oxygen species (ROS), pyroptosis and inflammatory response in macrophages were investigated. MaR1 significantly inhibited an excessive inflammatory response and proinflammatory markers during LPS/D-GalN-induced ALI. MaR1 markedly decreased the levels of ROS, tumor necrosis factor-α, and interleukin-1β (IL-1β) in macrophages, and limited hepatocyte apoptosis in vitro. Upon exploring the mechanisms underlying the protective role of MaR1, we found MaR1 markedly upregulated the nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and considerably reduced the phosphorylation of p38, ERK, and nuclear factor-kappa B (NF-κB)-p65. Knocking down Nrf2 decreased the effect of MaR1. Furthermore, we observed that MaR1 reduced inflammatory injury by inhibiting M1 macrophages and promoting M2 macrophage polarization. Finally, we observed that MaR1 could inhibit the production of gasdermin D N-terminus (GSDMD-N) in vivo. In vitro, MaR1 could significantly suppressed the expression of NLR family pyrin domain containing 3 (NLRP3) inflammasome, GSDMD-N, and IL-1β caused by LPS and nigericin stimulation in BMDMs. MaR1 could ameliorate inflammation during LPS/D-GalN induced ALI by suppressing mitogen-activated protein kinase /NF-κB signaling and NLRP3 inflammasome-induced pyroptosis, activating macrophage M1/M2 polarization and Nrf2/HO-1 signaling. This provides new evidence for the potential of developing MaR1 for ALI treatment.

Yang W ，Tao K ，Zhang P ，Chen X ，Sun X ，Li R ... -  《-》

Inhibition of endotoxin-induced acute lung injury in rats by bone marrow-derived mesenchymal stem cells: Role of Nrf2/HO-1 signal axis in inhibition of NLRP3 activation.

Both the Nuclear factor-erythroid 2 p45-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) antioxidant pathway and Nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) pathway are considered essential for the development of acute lung injury (ALI)/ARDS induced by sepsis. Our aim was to study the role of Nrf2/HO-1 pathway on activation of the NLRP3 in the protective effect of marrow mesenchymal stem cells (BMSCs) on LPS-induced ALI. We found that BMSCs ameliorated ALI as evidenced by 1) decreased histopathological injury, wet/dry ratio, and protein permeability index in lung; 2) decreased reactive oxygen species (ROS), malondialdehyde (MDA), and protein carbonyl content and restored the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in lung tissue; 3) reduced LPS-induced increase in inflammatory cell count and promotion of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 levels in bronchoalveolar lavage fluid (BALF); 4) improvement in the four-day survival rate of animals; and 5) enhanced expression of Nrf2 and HO-1 and decreased expression of NOD-like receptor protein 3(NLRP3) and caspase-1 (p20) in lung tissue. Of note, Nrf2 transcription factor inhibitor brusatol and HO-1 inhibitor tin protoporphyrin IX (SnppIX) reversed BMSCs induced down-expression of NLRP3 and caspase-1 (p20), and inhibited the protective effects of BMSCs. These findings demonstrated that the Nrf2-mediated HO-1 signaling pathway plays a critical role in the protective effects of BMSCs on LPS-induced ALI. BMSCs may play an anti-inflammatory effect partly through the Nrf2/HO-1-dependent NLRP3 pathway.

Lei L ，Guo Y ，Lin J ，Lin X ，He S ，Qin Z ，Lin Q ... -  《-》

5-Methoxytryptophan ameliorates endotoxin-induced acute lung injury in vivo and in vitro by inhibiting NLRP3 inflammasome-mediated pyroptosis through the Nrf2/HO-1 signaling pathway.

Endotoxin-induced acute lung injury (ALI) is a complicated and fatal condition with no specific or efficient clinical treatments. 5-Methoxytryptophan (5-MTP), an endogenous metabolite of tryptophan, was revealed to block systemic inflammation. However, the specific mechanism by which 5-MTP affects ALI still needs to be clarified. The purpose of this study was to determine whether 5-MTP protected the lung by inhibiting NLRP3 inflammasome-mediated pyroptosis through the Nrf2/HO-1 signaling pathway. We used lipopolysaccharide (LPS)-stimulated C57BL/6 J mice and MH-S alveolar macrophages to create models of ALI, and 5-MTP (100 mg/kg) administration attenuated pathological lung damage in LPS-exposed mice, which was associated with decreased inflammatory cytokines and oxidative stress levels, upregulated protein expression of Nrf2 and HO-1, and suppressed Caspase-1 activation and NLRP3-mediated pyroptosis protein levels. Moreover, Nrf2-deficient mice or MH-S cells were treated with 5-MTP to further confirm the protective effect of the Nrf2/HO-1 pathway on lung damage. We found that Nrf2 deficiency partially eliminated the beneficial effect of 5-MTP on reducing oxidative stress levels and inflammatory responses and abrogating the inhibition of NLRP3-mediated pyroptosis induced by LPS. These findings suggested that 5-MTP could effectively ameliorate ALI by inhibiting NLRP3-mediated pyroptosis via the Nrf2/HO-1 signaling pathway.

Ma Y ，Wang Z ，Wu X ，Ma Z ，Shi J ，He S ，Li S ，Li X ，Li X ，Li Y ，Yu J ... -  《-》