NLRP3 inflammasome as a target of berberine in experimental murine liver injury: interference with P2X7 signalling.

Berberine (BRB) is commonly used in herbal medicine, but its mechanisms of action are poorly understood. In the present study, we tested BRB in steatohepatitis induced by a methionine- and choline-deficient (MCD) diet, in acute acetaminophen intoxication and in cultured murine macrophages. BRB markedly improved parameters of liver injury and necroinflammation induced by the MCD diet, although increased mortality was observed by mechanisms independent of bacterial infections or plasma levels of BRB. The MCD diet induced up-regulation of all components of the NLRP3 (NACHT, LRR and PYD domain-containing protein 3) inflammasome, and increased hepatic levels of mature IL-1β (interleukin 1β). All of these parameters were significantly reduced in mice treated with BRB. In mice administered an acetaminophen overdose, a model dependent on inflammasome activation, BRB reduced mortality and ALT (alanine aminotransferase) elevation, and limited the expression of inflammasome components. In vitro, LPS (lipopolysaccharide)-induced activation of NLRP3 inflammasome in RAW264.7 murine macrophages was markedly decreased by pre-incubation with BRB. BRB significantly limited the activation of the purinergic receptor P2X7, involved in the late phases of inflammasome activation. Upon P2X7 knockdown, the ability of BRB to block LPS-induced secretion of IL-1β was lost. These data indicate that administration of BRB ameliorates inflammation and injury in two unrelated murine models of liver damage. We demonstrate for the first time that BRB interferes with activation of the NLRP3 inflammasome pathway in vivo and in vitro, through a mechanism based on interference with activation of P2X7, a purinergic receptor involved in inflammasome activation.

Vivoli E ，Cappon A ，Milani S ，Piombanti B ，Provenzano A ，Novo E ，Masi A ，Navari N ，Narducci R ，Mannaioni G ，Moneti G ，Oliveira CP ，Parola M ，Marra F ... -  《-》

P2X(7) receptor inhibition attenuated sympathetic nerve sprouting after myocardial infarction via the NLRP3/IL-1β pathway.

Mounting evidence supports the hypothesis that inflammation modulates sympathetic sprouting after myocardial infarction (MI). The myeloid P2X7 signal has been shown to activate the nucleotide-binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, a master regulator of inflammation. We investigated whether P2X7 signal participated in the pathogenesis of sympathetic reinnervation after MI, and whether NLRP3/interleukin-1β (IL-1β) axis is involved in the process. We explored the relationship between P2X7 receptor (P2X7 R) and IL-1β in the heart tissue of lipopolysaccharide (LPS)-primed naive rats. 3'-O-(4-benzoyl) benzoyl adenosine 5'-triphosphate (BzATP), a P2X7 R agonist, induced caspase-1 activation and mature IL-1β release, which was further neutralized by a NLRP3 inhibitor (16673-34-0). MI was induced by coronary artery ligation. Following infarction, a marked increase in P2X7 R was localized within infiltrated macrophages and observed in parallel with an up-regulation of NLRP3 inflammasome levels and the release of IL-1β in the left ventricle. The administration of A-740003 (a P2X7 R antagonist) significantly prevented the NLRP3/IL-1β increase. A-740003 and/or Anakinra (an IL-1 receptor antagonist) significantly reduced macrophage infiltration as well as macrophage-based IL-1β and NGF (nerve growth factor) production and eventually blunted sympathetic hyperinnervation, as assessed by the immunofluorescence of tyrosine hydroxylase (TH) and growth-associated protein 43 (GAP 43). Moreover, the use of Anakinra partly attenuated sympathetic sprouting. This indicated that the effect of P2X7 on neural remodelling was mediated at least partially by IL-1β. The arrhythmia score of programmed electric stimulation was in accordance with the degree of sympathetic hyperinnervation. In vitro studies showed that BzATP up-regulated secretion of nerve growth factor (NGF) in M1 macrophages via IL-1β. Together, these data indicate that P2X7 R contributes to neural and cardiac remodelling, at least partly mediated by NLRP3/IL-1β axis. Therapeutic interventions targeting P2X7 signal may be a novel approach to ameliorate arrhythmia following MI.

Yin J ，Wang Y ，Hu H ，Li X ，Xue M ，Cheng W ，Wang Y ，Li X ，Yang N ，Shi Y ，Yan S ... -  《-》

The purinergic 2X7 receptor participates in renal inflammation and injury induced by high-fat diet: possible role of NLRP3 inflammasome activation.

Renal disease associated with type 2 diabetes and the metabolic syndrome is characterized by a distinct inflammatory phenotype. The purinergic 2X7 receptor (P2X7 R) and the nucleotide-binding and oligomerization domain-like receptor containing a pyrin domain 3 (NLRP3) inflammasome have been separately shown to play a role in two models of non-metabolic chronic kidney disease. Moreover, the NLRP3 inflammasome has been implicated in chronic low-grade sterile inflammation characterizing metabolic disorders, though the mechanism(s) involved in inflammasome activation under these conditions are still unknown. We investigated the role of P2X7 R (through activation of the NLRP3 inflammasome) in renal inflammation and injury induced by a high-fat diet, an established model of the metabolic syndrome. On a high-fat diet, mice lacking P2X7 R developed attenuated renal functional and structural alterations as well as reduced inflammation, fibrosis, and oxidative/carbonyl stress, as compared with wild-type animals, in the absence of significant differences in metabolic parameters. This was associated with blunted up-regulation of the NLRP3 inflammasome components NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), pro-caspase 1, pro-interleukin (IL)-1β, and pro-IL-18, as well as reduced inflammasome activation, as evidenced by decreased formation of mature caspase 1, whereas mature IL-1β and IL-18 were not detected. Up-regulated expression of NLRP3 and pro-caspase 1, post-translational processing of pro-caspase-1, and release of IL-18 in response to lipopolysaccharide + 2'(3')-O-(4-benzoylbenzoyl)ATP were attenuated by P2X7 R silencing in cultured mouse podocytes. Protein and mRNA expression of P2X7 R, NLRP3, and ASC were also increased in kidneys from subjects with type 2 diabetes and the metabolic syndrome, showing histologically documented renal disease. These data provide evidence of a major role for the purinergic system, at least in part through activation of the NLRP3 inflammasome, in the process driving 'metabolic' renal inflammation and injury and identify P2X7 R and NLRP3 as novel therapeutic targets.

Solini A ，Menini S ，Rossi C ，Ricci C ，Santini E ，Blasetti Fantauzzi C ，Iacobini C ，Pugliese G ... -  《-》

Serum amyloid A activates the NLRP3 inflammasome via P2X7 receptor and a cathepsin B-sensitive pathway.

Niemi K ，Teirilä L ，Lappalainen J ，Rajamäki K ，Baumann MH ，Öörni K ，Wolff H ，Kovanen PT ，Matikainen S ，Eklund KK ... -  《-》

Aloe vera downregulates LPS-induced inflammatory cytokine production and expression of NLRP3 inflammasome in human macrophages.

Budai MM ，Varga A ，Milesz S ，Tőzsér J ，Benkő S ... -  《-》