NLRP3 inflammasome expression in idiopathic pulmonary fibrosis and rheumatoid lung.

In this study we investigated the implication of NLRP3 inflammasomes in the pathogenesis of idiopathic pulmonary fibrosis (IPF) and rheumatoid arthritis-usual interstitial pneumonia (RA-UIP).NLRP3 inflammasome activation at baseline and following stimulation with lipopolysaccharide/ATP was evaluated by measuring interleukin (IL)-1β and IL-18 levels released in the bronchoalveolar lavage fluid (BALF) fluid and by cultures of BALF cells. IL-1β and IL-18 levels were significantly elevated in the BALF and BALF macrophage cultures from RA-UIP patients, consistent with pre-existing inflammasome activation in these patients. In contrast, in IPF, BALF levels of IL-1β were significantly less elevated relative to RA-UIP and IL-18 was lower than controls. Furthermore, upon inflammasome stimulation, IPF BALF macrophage cultures failed to upregulate IL-1β and partly IL-18 secretion, in contrast to controls, which showed robust IL-1β and IL-18 upregulation. Interestingly, RA-UIP BALF cell cultures treated with lipopolysaccharide/ATP showed a potent stimulation of IL-18 secretion but not IL-1β, the latter being already elevated in the unstimulated cultures, while examination of the intracellular IL-1β levels in RA-UIP BALF cells upon NLRP3 inflammasome stimulation showed a significant upregulation of IL-1β suggesting the NLRP3 pathway could be further activated.Taken together, our results suggest distinct inflammasome activation profiles between autoimmune and idiopathic lung fibrosis.

Lasithiotaki I ，Giannarakis I ，Tsitoura E ，Samara KD ，Margaritopoulos GA ，Choulaki C ，Vasarmidi E ，Tzanakis N ，Voloudaki A ，Sidiropoulos P ，Siafakas NM ，Antoniou KM ... -  《-》

Pirfenidone ameliorates lipopolysaccharide-induced pulmonary inflammation and fibrosis by blocking NLRP3 inflammasome activation.

Acute respiratory distress syndrome(ARDS)is a severe clinical disorder characterized by its acute onset, diffuse alveolar damage, intractable hypoxemia, and non-cardiogenic pulmonary edema. Acute lung injury(ALI) can trigger persistent lung inflammation and fibrosis through activation of the NLRP3 inflammasome and subsequent secretion of mature IL-1β, suggesting that the NLRP3 inflammasome is a potential therapeutic target for ALI, for which new therapeutic approaches are needed. Our present study aims to assess whether pirfenidone,with anti-fibrotic and anti-inflammatory properties, can improve LPS-induced inflammation and fibrosis by inhibiting NLRP3 inflammasome activation. Male C57BL/6 J mice were intratracheally injected with LPS to induce ALI. Mice were administered pirfenidone by oral gavage throughout the entire experimental course. The mouse macrophage cell line (J774 A.1) was incubated with LPS and ATP, with or without PFD pre-treatment. We demonstrated that PFD remarkably ameliorated LPS-induced pulmonary inflammation and fibrosis and reduced IL-1β and TGF-β1 levels in bronchoalveolar lavage fluid(BALF). Pirfenidone substantially reduced NLRP3 and ASC expression and inhibited caspase-1 activation and IL-1β maturation in lung tissues. In vitro, the experiments revealed that PFD significantly suppressed LPS/ATP-induced production of reactive oxygen species (ROS) and decreased caspase-1 activation and the level of IL-1β in J774 A.1 cells. Taken together, the administration of PFD reduced LPS-induced lung inflammation and fibrosis by blocking NLRP3 inflammasome activation and subsequent IL-1β secretion. These findings indicated that PFD can down-regulate NLRP3 inflammasome activation and that it may offer a promising therapeutic approach for ARDS patients.

Li Y ，Li H ，Liu S ，Pan P ，Su X ，Tan H ，Wu D ，Zhang L ，Song C ，Dai M ，Li Q ，Mao Z ，Long Y ，Hu Y ，Hu C ... -  《-》

Enhanced IL-1β Release Following NLRP3 and AIM2 Inflammasome Stimulation Is Linked to mtROS in Airway Macrophages in Pulmonary Fibrosis.

Fibrotic Interstitial lung diseases (ILDs) are complex disorders of variable clinical behaviour. The majority of them cause significant morbidity, whilst Idiopathic Pulmonary Fibrosis (IPF) is recognised as the most relentless. NLRP3, AIM2, and NLRC4 inflammasomes are multiprotein complexes driving IL-1β release; a proinflammatory and profibrotic cytokine. Several pathogenetic factors associated with IPF are identified as inflammasome activators, including increases in mtROS and bacterial burden. Mitochondrial oxidation and alterations in bacterial burden in IPF and other ILDs may lead to augmented inflammasome activity in airway macrophages (AMs). IPF (n=14), non-IPF-ILDs (n=12) patients and healthy subjects (n=12) were prospectively recruited and AMs were isolated from bronchoalveolar lavage. IL-1β release resulting from NLRP3, AIM2 and NLRC4 inflammasomes stimulation in AMs were determined and baseline levels of mitochondrial ROS and microbial burden were also measured. Our results showed that NLRP3 was more inducible in IPF and other ILDs compared to controls. Additionally, following AIM2 activation IL-1β release was significantly higher in IPF compared to controls, whereas similar trends were observed in Non-IPF-ILDs. NLRC4 activation was similar across groups. mtROS was significantly associated with heightened NLRP3 and AIM2 activation, and mitochondrial antioxidant treatment limited inflammasome activation. Importantly, microbial burden was linked to baseline IL-1β release and AIM2 and IL-18 relative expression independently of mtROS. In conclusion, the above findings suggested a link between the overactivation of NLRP3 and AIM2 inflammasomes, driven by mitochondrial oxidation, in the pathogenesis of lung fibrosis while changes in the microbiota may prime the inflammasome in the lungs.

Trachalaki A ，Tsitoura E ，Mastrodimou S ，Invernizzi R ，Vasarmidi E ，Bibaki E ，Tzanakis N ，Molyneaux PL ，Maher TM ，Antoniou K ... -  《Frontiers in Immunology》

Comparison of Inhibitory Capacities of 6-, 8- and 10-Gingerols/Shogaols on the Canonical NLRP3 Inflammasome-Mediated IL-1β Secretion.

Ho SC ，Chang YH 《MOLECULES》

NLRP3 inflammasome activation and lung fibrosis caused by airborne fine particulate matter.

Airborne fine particulate matter (PM2.5) has been known capable of causing lung inflammation and fibrosis, as a result of a series of chronic respiration diseases. Although NLRP3 inflammasome activation is essential for development of many chronic diseases, the relationship between PM2.5-induced toxicological effect and NLRP3 inflammasome activation is rarely investigated. Since PM2.5 contains a large population of nanosized materials and many types of nanomaterials can activate NLRP3 inflammasome, the NLRP3 inflammasome activation and lung fibrosis induced by PM2.5 were investigated in the present study. PM2.5 was found capable of causing weak cell death but potent IL-1β secretion in THP-1 cells, which was involved in NLRP3 inflammasome activation as evidenced by Z-YVAD-FMK inhibited IL-1β secretion and overexpressed ASC and NLRP3 protein in PM2.5 treated cells. PM2.5 could be internalized into cells through multiple endocytosis processes, such as phagocytosis and pinocytosis (macropinocytosis, clathrin- and caveolin-mediated endocytosis), and activate NLRP3 inflammasome through cathepsin B release, ROS production, and potassium efflux. After 21 days of exposure to PM2.5 through oropharyngeal aspiration, Balb/c mice showed increased IL-1β and TGF-β1 levels in the bronchoalveolar lavage fluid (BALF) of lung and significant collagen deposition around small airways of mice, suggesting potential lung inflammation and pulmonary fibrosis.

Zheng R ，Tao L ，Jian H ，Chang Y ，Cheng Y ，Feng Y ，Zhang H ... -  《-》