Browsing by Subject "NLRP3"

Now showing 1 - 9 of 9
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    Danger signals released during cold ischemia storage activate NLRP3 inflammasome in myeloid cells and influence early allograft function in liver transplantation
    (Elsevier, 2022-12-19) Lucas-Ruiz, Fernando; Mateo, Sandra V.; Jover-Aguilar, Marta; Alconchel, Felipe; Martínez-Alarcón, Laura; Torre-Minguela, Carlos de; Vidal-Correoso, Daniel; Villalva-López, Francisco; López-López, Víctor; Rios-Zambudio, Antonio; Pons Miñano, José Antonio; Ramírez, Pablo; Baroja-Mazo, Alberto; Pelegrín Vivancos, Pablo; Medicina
    Background Innate immunity plays a fundamental role in solid organ transplantation. Myeloid cells can sense danger signals or DAMPs released after tissue or cell damage, such as during ischemia processes. This study aimed to identify DAMPs released during cold ischemia storage of human liver and analyze their ability to activate the inflammasome in myeloid cells and the possible implications in terms of short-term outcomes of liver transplantation. Methods 79 samples of organ preservation solution (OPS) from 79 deceased donors were collected after cold static storage. We used different analytical methods to measure DAMPs in these end-ischemic OPS (eiOPS) samples. We also used eiOPS in the human macrophage THP-1 cell line and primary monocyte cultures to study inflammasome activation. Findings Different DAMPs were identified in eiOPS, several of which induced both priming and activation of the NLRP3 inflammasome in human myeloid cells. Cold ischemia time and donation after circulatory death negatively influenced the DAMP signature. Moreover, the presence of oligomeric inflammasomes and interleukin-18 in eiOPS correlated with early allograft dysfunction in liver transplant patients. Interpretation DAMPs released during cold ischemia storage prime and activate the NLRP3 inflammasome in liver macrophages after transplantation, inducing a pro-inflammatory environment that will complicate the outcome of the graft. The use of pharmacological blockers targeting DAMPs or the NLRP3 inflammasome in liver ischemia during static cold storage or through extracorporeal organ support could be a suitable strategy to increase the success of liver transplantation.
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    Decreased survival in patients with pancreatic cancer may be associated with an increase in histopathological expression of inflammasome marker NLRP3
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2024) Fraile Martínez, Oscar; García Montero, Cielo; Pekarek, Leonel; Saz, Jose V.; Álvarez Mon, Miguel Ángel; Barrena Blázquez, Silvestra; García Honduvilla, Natalio; Buján, Julia; Asúnsolo, Ángel; Coca, Santiago; Álvarez Mon, Melchor; Guijarro, Luis G.; Saez, Miguel A.; Ortega, Miguel A.
    Pancreatic cancer is a malignant neoplasm that, despite its low frequency, has a 5-year survival rate of less than 10%. The study of different histopathological markers has allowed a better understanding of the onset and development of this type of tumor as well as facilitating an approach to clinical variables based on their diagnostic, prognostic, and predictive value. In this sense, the NLRP3 protein of the inflammasome has been shown to be a component of great relevance in the initiation and progression of pancreatic cancer, although the value of this biomarker in patients has not yet been clarified. In this study, we selected 41 patients with pancreatic cancer and followed them for 60 months (5 years), evaluating their NLRP3 expression using immunohistochemical techniques. Furthermore, by performing Kaplan-Meier curves, we evaluated the survival of these patients in relation to their NLRP3 expression. Our results show that a significant percentage of our cohort had high expression of this component (90.74%) and that there is an inverse relationship between the expression of NLRP3 and patient survival. High levels of NLRP3 expression are related to lower survival and worse prognosis in these patients, possibly due to an ineffective immune system response and increased tumor-promoted inflammation. Future studies should be aimed at confirming these results in larger groups and evaluating various clinical strategies based on this knowledge.
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    Dynamics of macrophage polarization reveal new mechanism to inhibit IL-1beta release through pyrophosphates
    (EMBO Press, 2009) Pelegrin, Pablo; Surprenant, Annmarie; Bioquímica y Biología Molecular B e Inmunología
    In acute inflammation extracellular ATP activates P2X7 ion channel receptors (P2X7R) on M1 polarized macrophages to release pro-inflammatory IL-1bvia activation of the caspase-1/Nucleotide-binding domain and Leucine-rich repeat receptor containing Pyrin domain 3 (NLRP3) inflammasome. In contrast, M2 polarized macrophages are critical to the resolution of inflammation but neither actions of P2X7R on these macrophages, nor mechanisms by which macrophages switch from pro-inflammatory to anti-inflammatory phenotypes, are known. Here we investigated extracellular ATP signaling over a dynamic macrophage polarity gradient from M1 through M2 phenotypes. In macrophages polarized towards, but not at, M2 phenotype, where intracellular IL-1b remains high and the inflammasome is intact, P2X7R activation selectively uncouples to the NLRP3-inflammasome activation but not to upstream ion channel activation. In these intermediate M1/M2 polarized macrophages, extracellular ATP now acts via its pyrophosphate chains, independently of other purine receptors, to inhibit IL-1b release by other stimuli via two independent mechanisms: inhibition of ROS production and trapping of the inflammasome complex via intracellular clustering of actin filaments.
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    Inflammatory suppression and immunity regulation benefits of honokiol in a rat model of acute peritonitis via the regulation of NLRP3 inflammasome and Sirt1/autophagy axis
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2024) Pan, Ximing; Hua, Zhou; Fan, Guocai; Feng, Qinglong
    Background. NLRP3 inflammasome and Sirt1/autophagy axis are potential targets for advancing acute peritonitis (AP). Honokiol (HNK), a bioactive substance, has the potential to improve AP. Materials and methods. The AP model rats were established by cecal ligation and puncture (CLP). Rats were randomized into the Sham, Sham+HNK, CLP, and CLP+HNK groups. The therapeutic effects of HNK on organ infection, inflammation and immunity were observed in AP rats. The inflammation of RAW 264.7 cells was induced by lipopolysaccharide (LPS) and divided into the Control, HNK, LPS, and LPS+HNK groups. The effects of HNK on immunity and inflammation were observed. Moreover, the inflammatory cell model was further transfected with NLRP3 overexpressing plasmid, and the regulatory effect of HNK on NLRP3 in AP cells was detected. Results. HNK treatment improved survival, biochemical indexes, and lung and kidney injury and inhibited inflammatory cytokine release and bacterial infection in CLP rats. In CLP rats and RAW 264.7 cells, HNK treatment improved the release of the CD4+ and CD8+ T cells, decreased the associated proteins’ levels of the NLRP3 inflammasome, and activated the expression of proteins in the Sirt1/autophagy axis. It improved viability and reduced apoptosis and the degrees of TNF-α, IL-1β, and IL-6 mRNA in RAW 264.7 cells. In addition, HNK treatment antagonized the effect of NLRP3-overexpressed on inflammation and immunity. Conclusions. HNK improved AP by inhibiting NLRP3 inflammasome and activating the Sirt1 autophagy axis in vivo and in vitro.
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    METTL1 aggravates sepsis-acute kidney injury by promoting m7G methylation of NLRP3-mediated pyroptosis
    (2025) Yuexuan Chen; Ming Fang; Jingjing Hu; Lu Wang; Biología Celular e Histología
    Sepsis is a major cause of acute kidney injury (AKI). Dysregulation of N7-methyladenosine (m7G) methylation is a pathogenic mechanism of sepsis. However, the role of m7G methylation in renal damage remains poorly understood. In this study, we investigated the regulation of METTL1, an m7G "writer", on pyroptosis in sepsis-induced AKI. HK-2 cells were treated with lipopolysaccharide (LPS), and pyroptosis was assessed using enzyme-linked immunosorbent assays and western blotting. The m7G methylation status of NLRP3 was analyzed through methylated-RNA immunoprecipitation (Me-RIP), RNA immuno-precipitation (RIP), and dual-luciferase reporter assays. Renal injury in mice subjected to cecal ligation and puncture (CLP) was evaluated using hematoxylin and eosin (H&E) staining. Our results demonstrated that METTL1 expression was significantly upregulated in both LPS-treated HK-2 cells and the CLP-induced mouse model. Interfering with METTL1 suppressed LPS-induced pyroptosis in vitro and attenuated kidney damage and pyroptosis in vivo. Furthermore, METTL1 knockdown inhibited m7G methylation of NLRP3, thereby reducing its stability. Overexpression of NLRP3 abrogated the inhibition of pyroptosis caused by METTL1 knockdown. In conclusion, silencing of METTL1 alleviates sepsis-induced AKI by inhibiting m7G methylated NLRP3-mediated pyroptosis in renal tubular epithelial cells. These findings suggest that targeting METTL1 may represent a promising therapeutic strategy for managing sepsis-associated AKI.
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    Penning decoction ameliorated pyroptosis in mice with lipopolysaccharide-induced endometritis through inhibition of the TLR4/NF-κB/NLRP3 pathway
    (2026) Chen Chen; Yuqiong Yuan; Zhihui Liu; Qianru Zhou; Jiani Shi; Biología Celular e Histología; Universidad de Murcia, Departamento de Biología Celular e Histología
    Objectives. Endometritis, stemming from bacterial infection, manifests as persistent inflammation and may cause infertility. Penning decoction (PND) has been approved for clinical treatment of patients with endometritis. However, the mechanism by which it prevents endometritis remains unknown. This study aimed to examine the impact of PND on lipopoly saccharide (LPS)-induced endometritis and elucidate the underlying mechanisms involved. Methods. Firstly, ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS) analysis, in which both positive and negative ion modes were used to identify the chemical compounds in PND, was performed. The antipyroptotic effects of PND were validated in LPS-induced endometritis mice. Additionally, mouse endometrial epithelial cells (MEECs) were used to explore the molecular mechanism of PND in serum in vitro. Results. A total of 145 chemical compounds, including flavones, saponins, polysaccharides, alkaloids, and glycosides, were identified in positive and negative ion modes. The results showed that LPS could induce pyroptosis in endometritis in vivo and in vitro. Treatment with PND or serum containing PND could significantly ameliorate LPS-induced pyroptosis by inhibiting the activation of the TLR4/NF-κB/NLRP3 signaling pathway. Conclusion. Our results demonstrated that PND may improve LPS-induced endometritis by inhibiting the TLR4/NF-κB/NLRP3 pathway, which provides a potentially effective drug for the clinical treatment of endometritis.
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    Priming is dispensable for NLRP3 inflammasome activation in human monocytes in vitro
    (Frontiers Media, 2020-09-30) Martín Sánchez, María Rosario Fátima; Gritsenko, Anna; Yu, Shi; Díaz del Olmo, Inés; Nichols, Eva María; Davis, Daniel M.; Brough, David; López Castejón, Gloria; Farmacología
    Interleukin (IL)-18 and IL-1b are potent pro-inflammatory cytokines that contribute toinflammatory conditions such as rheumatoid arthritis and Alzheimer’s disease. They areproduced as inactive precursors that are activated by large macromolecular complexescalled inflammasomes upon sensing damage or pathogenic signals. NLRP3inflammasome activation is regarded to require a priming step that causes NLRP3 andIL-1b gene upregulation, and also NLRP3 post-translational licencing. A subsequentactivation step leads to the assembly of the complex and the cleavage of pro-IL-18 andpro-IL-1b by caspase-1 into their mature forms, allowing their release. Here we show thathuman monocytes, but not monocyte derived macrophages, are able to form canonicalNLRP3 inflammasomes in the absence of priming. NLRP3 activator nigericin caused theprocessing and release of constitutively expressed IL-18 in an unprimed setting. This wasmediated by the canonical NLRP3 inflammasome that was dependent on K + and Cl−efflux and led to ASC oligomerization, caspase-1 and Gasdermin-D (GSDMD) cleavage.IL-18 release was impaired by the NLRP3 inhibitor MCC950 and by the absence ofNLRP3, but also by deficiency of GSDMD, suggesting that pyroptosis is the mechanism ofrelease. This work highlights the readiness of the NLRP3 inflammasome to assemble inthe absence of priming in human monocytes and hence contribute to the very early stagesof the inflammatory response when IL-1b has not yet been produced. It is important toconsider the unprimed setting when researching the mechanisms of NLRP3 activation, asto not overshadow the pathways that occur in the absence of priming stimuli, which mightonly enhance this response.
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    Sensing low intracellular potassium by NLRP3 results in a stable open structure that promotes inflammasome activation
    (American Association for the Advancement of Science, 2021-09-15) Angosto-Bazarra, Diego; Alarcón-Vila, Cristina; Baños, Maria C; Hafner-Bratkovič, Iva; Oliva, Baldomero; Pelegrín Vivancos, Pablo; Tapia Abellán, Ana; Bioquímica y Biología Molecular B e Inmunología
    The NLRP3 inflammasome is activated in response to a wide range of stimuli and drives diverse inflammatory diseases. The decrease of intracellular K+ concentration is a minimal upstream signal to most of the different NLRP3 activation models. Here we found that cellular K+ efflux induces a stable structural change in the inactive NLRP3 promoting an open conformation as a step preceding activation. This conformational change is facilitated by the presence of the specific NLRP3 FISNA domain and a unique flexible linker sequence between the PYD and FISNA domains. This linker is also important to facilitate the ensemble of NLRP3PYD into a seed structure for ASC oligomerization. The introduction of the NLRP3 PYD-linker-FISNA sequence into NLRP6 resulted in a chimeric receptor able to be activated by K+ efflux-specific NLRP3 activators and promoted an in vivo inflammatory response to uric acid crystals. Our results establish that the N-terminal sequence between PYD and NACHT domain of NLRP3 is key for inflammasome activation.
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    Sphingosine Kinase-1 (SPHK1) promotes inflammation in infantile pneumonia by regulating NLRP3 inflammasome and SIRT1 expression
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2022) Ding, Niu; Meng, Yanni; Liu, Lianhong; Ma, Song; Chen, Yanping
    Background. Infantile pneumonia is an acute inflammatory disorder of the lung caused by mycoplasma pneumonia. SPHK1 (sphingosine kinase-1) signaling pathway is involved in the process of inflammatory diseases. However, whether SphK1 regulates inflammatory responses in infantile pneumonia remains unclear. In this study, we investigated the role of SPHK1 in infantile pneumonia and its underlying mechanisms. Methods. Serum samples of 12 patients with infantile pneumonia and healthy controls were obtained from Hunan Children's Hospital. To induce pneumonia, mice were administrated with LPS (lipopolysaccharide) into the lung. RAW264.7 cells were used as an in vitro macrophage model stimulated with LPS or PBS for 4 h. Results. SPHK1 mRNA level and protein level in the LPS-treated mice and patients with infantile pneumonia were significantly increased. SPHK1 promoted inflammation and lung injury in mice with infantile pneumonia. The knockdown of SPHK1 expression inhibited inflammation and restrained lung injury in mice with infantile pneumonia. SPHK1 overexpression also exacerbated inflammation in RAW264.7 cells stimulated by LPS, and SPHK1 silencing reduced inflammatory responses. We further showed that SPHK1 induced NLRP3 (NLR Family Pyrin Domain Containing 3) activity by inhibiting SIRT1 expression. Conclusion. Our study demonstrated that SPHK1 promotes inflammation of infantile pneumonia by modulating NLRP3 inflammasome via the regulation of SIRT1 expression and mitochondrial permeability transition