A Novel Mechanism of Mesenchymal Stromal Cell-Mediated Protection against Sepsis: Restricting Inflammasome Activation in Macrophages by Increasing Mitophagy and Decreasing Mitochondrial ROS

Sepsis, a systemic inflammatory response to infection, is the leading cause of death in the intensive care unit (ICU). Previous studies indicated that mesenchymal stromal cells (MSCs) might have therapeutic potential against sepsis. The current study was designed to investigate the effects of MSCs on sepsis and the underlying mechanisms focusing on inflammasome activation in macrophages. The results demonstrated that the bone marrow-derived mesenchymal stem cells (BMSCs) significantly increased the survival rate and organ function in cecal ligation and puncture (CLP) mice compared with the control-grouped mice. BMSCs significantly restricted NLRP3 inflammasome activation, suppressed the generation of mitochondrial ROS, and decreased caspase-1 and IL-1β activation when cocultured with bone marrow-derived macrophages (BMDMs), the effects of which could be abolished by Mito-TEMPO. Furthermore, the expression levels of caspase-1, IL-1β, and IL-18 in BMDMs were elevated after treatment with mitophagy inhibitor 3-MA. Thus, BMSCs exert beneficial effects on inhibiting NLRP3 inflammasome activation in macrophages primarily via both enhancing mitophagy and decreasing mitochondrial ROS. These findings suggest that restricting inflammasome activation in macrophages by increasing mitophagy and decreasing mitochondrial ROS might be a crucial mechanism for MSCs to combat sepsis.

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The Essential Oil of Artemisia argyi H.Lév. and Vaniot Attenuates NLRP3 Inflammasome Activation in THP-1 Cells

Frontiers in Pharmacology ◽

10.3389/fphar.2021.712907 ◽

2021 ◽

Vol 12 ◽

Author(s):

Pengxiao Chen ◽

Qi Bai ◽

Yanting Wu ◽

Qiongzhen Zeng ◽

Xiaowei Song ◽

...

Keyword(s):

Essential Oil ◽

Nlrp3 Inflammasome ◽

Therapeutic Potential ◽

Inflammasome Activation ◽

Caspase 1 ◽

Artemisia Argyi ◽

Nlrp3 Inflammasome Activation ◽

Long Time

Artemisia argyi H. Lév. and Vaniot is a traditional medical herb that has been used for a long time in China and other Asian counties. Essential oil is the main active fraction of Artemisia argyi H. Lév. and Vaniot, and its anti-inflammatory potential has been observed in vitro and in vivo. Here, we found that the essential oil of Artemisia argyi H. Lév. and Vaniot (EOAA) inhibited monosodium urate (MSU)- and nigericin-induced NLRP3 inflammasome activation. EOAA suppressed caspase-1 and IL-1β processing and pyroptosis. NF-κB p65 phosphorylation and translocation were also inhibited. In addition, EOAA suppressed nigericin-induced NLRP3 inflammasome activation without blocking ASC oligomerization, suggesting that it may inhibit NLRP3 inflammasome activation by preventing caspase-1 processing. Our study thus indicates that EOAA inhibits NLRP3 inflammasome activation and has therapeutic potential against NLRP3-driven diseases.

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Stavudine Reduces NLRP3 Inflammasome Activation and Upregulates Aβ-Autophagy

10.1101/377945 ◽

2018 ◽

Cited By ~ 2

Author(s):

Francesca La Rosa ◽

Marina Saresella ◽

Ivana Marventano ◽

Federica Piancone ◽

Enrico Ripamonti ◽

...

Keyword(s):

Nlrp3 Inflammasome ◽

Inflammasome Activation ◽

Clinical Scenario ◽

Rt Pcr ◽

Reverse Transcriptase Inhibitors ◽

Beneficial Effects ◽

Caspase 1 ◽

Nlrp3 Inflammasome Activation ◽

Aβ Clearance

AbstractAlzheimer’s disease (AD) is associated with amyloid-beta (Aβ) deposition and neuroinflammation, possibly driven by activation of the NLRP3 inflammasome. Nucleoside reverse transcriptase inhibitors (NRTI) hamper the assembly of the NLRP3 inflammasome; we analyzed whether stavudine (D4T), a prototypical NRTI, modulates Aβ-mediated inflammasome activation; because neuroinflammation impairs Aβ clearance by phagocytes, phagocytosis and autophagy were examined as well. THP-1-derived macrophages were stimulated in vitro with Aβ42 alone or after LPS priming with/without D4T. NLRP3 and TREM2 expression was analyzed by RT-PCR, phagocytosis and ASC-Speck by AmnisFlowSight, NLRP3-produced cytokines by ELISA, authophagy by P-ELISA evaluation of P-ERK and P-AKT. Results showed that IL1β, IL18 and caspase-1 were increased whereas Aβ-phagocytosis and TREM2 were reduced in LPS+Aβ42-stimulated cells. D4T reduced NLRP3 assembly as well as IL18 and caspase-1 production, but not IL1β, phagocytosis, and TREM2. P-AKT expression was augmented and P-ERK was reduced by D4T, suggesting a stimulatory effect on autophagy. D4T reduces NLRP3 inflammasome-associated inflammation, possibly restoring autophagy, in an in vitro model of AD; it will be interesting to verify its possibly beneficial effects in the clinical scenario.

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Riboflavin, vitamin B2, attenuates NLRP3, NLRC4, AIM2, and non-canonical inflammasomes by the inhibition of caspase-1 activity

Scientific Reports ◽

10.1038/s41598-020-76251-7 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Huijeong Ahn ◽

Geun-Shik Lee

Keyword(s):

Nlrp3 Inflammasome ◽

Energy Production ◽

Antioxidant Properties ◽

Nutritional Supplement ◽

Antioxidant Effect ◽

Inflammasome Activation ◽

Caspase 1 ◽

Mitochondrial Ros ◽

Nlrp3 Inflammasome Activation ◽

Dna Release

Abstract Riboflavin is commonly taken as a nutritional supplement, and it converts to coenzymes during the process of energy production from carbohydrates, fats, and proteins. Although riboflavin is considered to be an anti-inflammatory vitamin because of its antioxidant properties, the effects of riboflavin on inflammasome have been not reported. Inflammasome, a cytosolic surveillance protein complex, leads to the activation of caspase-1, cytokine maturation, and pyroptosis. In the present study, riboflavin attenuated the indicators of NLRP3 inflammasome activation in macrophages, such as the maturation and secretion of interleukin (IL)-1β, IL-18, and caspase-1; the formation of Asc pyroptosome; and the cleavage of gasdermin D. In addition, the oral and peritoneal administration of riboflavin inhibited the peritoneal production of IL-1β and IL-18 in a mouse model. Mechanistically, riboflavin prevented mitochondrial perturbations, such as mitochondrial ROS production and mitochondrial DNA release, which trigger the NLRP3 inflammasome assembly. Riboflavin was further confirmed to disrupt the activity of caspase-1, and it also inhibited the AIM2, NLRC4, and non-canonical inflammasomes. Therefore, riboflavin has both an antioxidant effect and an anti-inflammasome property that regulates the inflammatory response.

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Rhein, An Anthraquinone Drug, Suppresses the NLRP3 Inflammasome and Macrophage Activation in Urate Crystal-Induced Gouty Inflammation

The American Journal of Chinese Medicine ◽

10.1142/s0192415x19500071 ◽

2019 ◽

Vol 47 (01) ◽

pp. 135-151 ◽

Cited By ~ 8

Author(s):

Wan-Chun Chang ◽

Mu-Tzu Chu ◽

Chih-Yuan Hsu ◽

Yeong-Jian Jan Wu ◽

Jing-Yi Lee ◽

...

Keyword(s):

Nlrp3 Inflammasome ◽

Therapeutic Potential ◽

Inflammatory Diseases ◽

Gouty Arthritis ◽

Inflammasome Activation ◽

Mrna Levels ◽

Caspase 1 ◽

Text Production ◽

Nlrp3 Inflammasome Activation ◽

Urate Crystal

Rhein, an anthraquinone drug, is a widely used traditional Chinese medicine. Rhein is a major bioactive metabolite of diacerein which has been approved for treating osteoarthritis with a good safety profile in humans. Gouty arthritis is an inflammatory disease characterized by urate crystal-induced NLRP3 inflammasome activation with up-regulated caspase-1 protease and IL-1[Formula: see text] in macrophages. Inhibition of the NLRP3 inflammasome formation has been considered as a potential therapeutic avenue for treating or preventing many inflammatory diseases. This study aimed to evaluate the anti-inflammatory effects of rhein on gouty arthritis. Rhein within the physiological levels of humans showed no toxicity on the cell viability and differentiation, but significantly decreased the production of IL-1[Formula: see text], TNF-[Formula: see text] and caspase-1 protease in urate crystal-activated macrophages. Compared to medium controls, rhein at the therapeutic concentration (2.5[Formula: see text][Formula: see text]g/mL) effectively inhibited IL-1[Formula: see text] production by 47% ([Formula: see text]). Rhein did not affect the mRNA levels of CASP1, NLRP3 and ASC, but suppressed the protein expression and enzyme activity of caspase-1. Immunofluorescence confocal microscopy further revealed that rhein suppressed the aggregation of ASC speck and inhibited the formation of NLRP3 inflammasome. Rhein of 5[Formula: see text][Formula: see text]g/mL significantly decreased the ASC speck to 36% ([Formula: see text]), and reduced the NLRP3 aggregates to 37.5% ([Formula: see text]). Our data demonstrate that rhein possesses pharmacological activity to suppress caspase-1 protease activity and IL-1[Formula: see text] production by interfering with the formation of NLRP3 multiprotein complex. These results suggest that rhein has therapeutic potential for treating NLRP3 inflammasome-mediated diseases such as gouty arthritis.

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Gallic Acid Alleviates Gouty Arthritis by Inhibiting NLRP3 Inflammasome Activation and Pyroptosis Through Enhancing Nrf2 Signaling

Frontiers in Immunology ◽

10.3389/fimmu.2020.580593 ◽

2020 ◽

Vol 11 ◽

Author(s):

Yuqing Lin ◽

Tianyu Luo ◽

Anli Weng ◽

Xiaodi Huang ◽

Yanqing Yao ◽

...

Keyword(s):

Gallic Acid ◽

Nlrp3 Inflammasome ◽

Therapeutic Potential ◽

Gouty Arthritis ◽

Inhibitory Effect ◽

Ros Generation ◽

Inflammasome Activation ◽

Related Factor ◽

Caspase 1 ◽

Nlrp3 Inflammasome Activation

Gallic acid is an active phenolic acid widely distributed in plants, and there is compelling evidence to prove its anti-inflammatory effects. NLRP3 inflammasome dysregulation is closely linked to many inflammatory diseases. However, how gallic acid affects the NLRP3 inflammasome remains unclear. Therefore, in the present study, we investigated the mechanisms underlying the effects of gallic acid on the NLRP3 inflammasome and pyroptosis, as well as its effect on gouty arthritis in mice. The results showed that gallic acid inhibited lactate dehydrogenase (LDH) release and pyroptosis in lipopolysaccharide (LPS)-primed and ATP-, nigericin-, or monosodium urate (MSU) crystal-stimulated macrophages. Additionally, gallic acid blocked NLRP3 inflammasome activation and inhibited the subsequent activation of caspase-1 and secretion of IL-1β. Gallic acid exerted its inhibitory effect by blocking NLRP3-NEK7 interaction and ASC oligomerization, thereby limiting inflammasome assembly. Moreover, gallic acid promoted the expression of nuclear factor E2-related factor 2 (Nrf2) and reduced the production of mitochondrial ROS (mtROS). Importantly, the inhibitory effect of gallic acid could be reversed by treatment with the Nrf2 inhibitor ML385. NRF2 siRNA also abolished the inhibitory effect of gallic acid on IL-1β secretion. The results further showed that gallic acid could mitigate MSU-induced joint swelling and inhibit IL-1β and caspase 1 (p20) production in mice. Moreover, gallic acid could moderate MSU-induced macrophages and neutrophils migration into joint synovitis. In summary, we found that gallic acid suppresses ROS generation, thereby limiting NLRP3 inflammasome activation and pyroptosis dependent on Nrf2 signaling, suggesting that gallic acid possesses therapeutic potential for the treatment of gouty arthritis.

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LRRFIP2 negatively regulates NLRP3 inflammasome activation in macrophages by promoting Flightless-I-mediated caspase-1 inhibition

Nature Communications ◽

10.1038/ncomms3075 ◽

2013 ◽

Vol 4 (1) ◽

Cited By ~ 49

Author(s):

Jing Jin ◽

Qian Yu ◽

Chaofeng Han ◽

Xiang Hu ◽

Sheng Xu ◽

...

Keyword(s):

Nlrp3 Inflammasome ◽

Inflammasome Activation ◽

Caspase 1 ◽

Nlrp3 Inflammasome Activation

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Pharmacological Blocker of NF-κb and Mitochondrial Ros Restrict NLRP3 Inflammasome Activation and Rescue Dopaminergic Neurons in Vitro and in Vivo Parkinson’s Disease

10.21203/rs.3.rs-260478/v1 ◽

2021 ◽

Author(s):

Sahabuddin Ahmed ◽

Samir Ranjan Panda ◽

Mohit Kwatra ◽

Bidya Dhar Sahu ◽

VGM Naidu

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Free Radicals ◽

Nlrp3 Inflammasome ◽

Nuclear Translocation ◽

Inflammasome Activation ◽

Mitochondrial Ros ◽

Nlrp3 Inflammasome Activation

Abstract Several activators of NLRP3 inflammasome have been described; however, the central mechanisms of NLRP3 inflammasome activation in brain microglia, especially at the activating step through free radical generation, still require further clarification. Hence the present study aimed to investigate the role of free radicals in activating NLRP3 inflammasome driven neurodegeneration and elucidated the neuroprotective role of perillyl alcohol (PA) in vitro and in vivo models of Parkinson’s disease. Initial priming of microglial cells with lipopolysaccharide (LPS) following treatment with hydrogen peroxide (H2O2) induces NF-κB translocation to nucleus with robust generation of free radicals that act as Signal 2 in augmenting NLRP3 inflammasome assembly and its downstream targets. PA treatment suppresses nuclear translocation of NF-κB and maintains cellular redox homeostasis in microglia that limits NLRP3 inflammasome activation along with processing active caspase-1, IL-1β and IL-18. To further correlates the in vitro study with in vivo MPTP model, treatment with PA also inhibits the nuclear translocation of NF-κB and downregulates the NLRP3 inflammasome activation. PA administration upregulates various antioxidant enzymes levels and restored the level of dopamine and other neurotransmitters in the striatum of the mice brain with improved behavioural activities. Additionally, treatment with Mito-TEMPO (a mitochondrial ROS inhibitor) was also seen to inhibit NLRP3 inflammasome and rescue dopaminergic neuron loss in the mice brain. Therefore, we conclude that NLRP3 inflammasome activation requires a signal from damaged mitochondria for its activation. Further pharmacological scavenging of free radicals restricts microglia activation and simultaneously supports neuronal survival via targeting NLRP3 inflammasome pathway in Parkinson’s disease.

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ASC deglutathionylation is a checkpoint for NLRP3 inflammasome activation

Journal of Experimental Medicine ◽

10.1084/jem.20202637 ◽

2021 ◽

Vol 218 (9) ◽

Author(s):

Shuhang Li ◽

Linlin Wang ◽

Zhihao Xu ◽

Yuanyuan Huang ◽

Rufeng Xue ◽

...

Keyword(s):

Metabolic Control ◽

Nlrp3 Inflammasome ◽

Inflammasome Activation ◽

Mitochondrial Ros ◽

Nlrp3 Inflammasome Activation ◽

Multiple Molecules ◽

Excessive Activation

Activation of NLRP3 inflammasome is precisely controlled to avoid excessive activation. Although multiple molecules regulating NLRP3 inflammasome activation have been revealed, the checkpoints governing NLRP3 inflammasome activation remain elusive. Here, we show that activation of NLRP3 inflammasome is governed by GSTO1-promoted ASC deglutathionylation in macrophages. Glutathionylation of ASC inhibits ASC oligomerization and thus represses activation of NLRP3 inflammasome in macrophages, unless GSTO1 binds ASC and deglutathionylates ASC at ER, under control of mitochondrial ROS and triacylglyceride synthesis. In macrophages expressing ASCC171A, a mutant ASC without glutathionylation site, activation of NLRP3 inflammasome is GSTO1 independent, ROS independent, and signal 2 less dependent. Moreover, AscC171A mice exhibit NLRP3-dependent hyperinflammation in vivo. Our results demonstrate that glutathionylation of ASC represses NLRP3 inflammasome activation, and GSTO1-promoted ASC deglutathionylation at ER, under metabolic control, is a checkpoint for activating NLRP3 inflammasome.

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