Ergolide covalently binds NLRP3 and inhibits NLRP3 inflammasome-mediated pyroptosis.

BACKGROUND: NLR family pyrin domain-containing 3 (NLRP3)-mediated pyroptosis plays a key role in various acute and chronic inflammatory diseases. Targeted inhibition of NLRP3-mediated pyroptosis may be a potential therapeutic strategy for various inflammatory diseases. Ergolide (ERG) is a sesquiterpene lactone natural product derived from the traditional Chinese medicinal herb, Inula britannica. ERG has been shown to have anti-inflammatory and anti-cancer activities, but the target is remains unknown. HYPOTHESIS/PURPOSE: This study performed an in-depth investigation of the anti-inflammatory mechanism of ERG in NLRP3-mediated pyroptosis and NLPR3 inflammasome related sepsis and acute lung injury model. METHODS: ELISA and Western blot were used to determine the IL-1ß and P20 levels. Co-immunoprecipitation assays were used to detect the interaction between proteins. Drug affinity response target stability (DARTS) assays were used to explore the potential target of ERG. C57BL/6J mice were intraperitoneally injected with E. coli DH5α (2 × 109 CFU/mouse) to establish a sepsis model. Acute lung injury was induced by intratracheal administrationof lipopolysaccharide in wild-type mice and NLRP3 knockout mice with or without ERG treatment. RESULTS: We showed that ERG is an efficient inhibitor of NLRP3-mediated pyroptosis in the first and second signals of NLRP3 inflammasome activation. Furthermore, we demonstrated that ERG irreversibly bound to the NACHT domain of NLRP3 to prevent the assembly and activation of the NLRP3 inflammasome. ERG remarkably improved the survival rate of wild-type septic mice. In lipopolysaccharide-induced acute lung injury model, ERG alleviated acute lung injury of wild-type mice but not NLRP3 knockout mice. CONCLUSION: Our results revealed that the anti-pyroptosis effect of ERG are dependent on NLRP3 and NLRP3 NACHT domain is ERG's direct target. Therefore, ERG can serve as a precursor drug for the development of novel NLRP3 inhibitors to treat NLRP3 inflammasome mediated inflammatory diseases.

Costunolide covalently targets NACHT domain of NLRP3 to inhibit inflammasome activation and alleviate NLRP3-driven inflammatory diseases.

The NLRP3 inflammasome's core and most specific protein, NLRP3, has a variety of functions in inflammation-driven diseases. Costunolide (COS) is the major active ingredient of the traditional Chinese medicinal herb Saussurea lappa and has anti-inflammatory activity, but the principal mechanism and molecular target of COS remain unclear. Here, we show that COS covalently binds to cysteine 598 in NACHT domain of NLRP3, altering the ATPase activity and assembly of NLRP3 inflammasome. We declare COS's great anti-inflammasome efficacy in macrophages and disease models of gouty arthritis and ulcerative colitis via inhibiting NLRP3 inflammasome activation. We also reveal that the α-methylene-γ-butyrolactone motif in sesquiterpene lactone is the certain active group in inhibiting NLRP3 activation. Taken together, NLRP3 is identified as a direct target of COS for its anti-inflammasome activity. COS, especially the α-methylene-γ-butyrolactone motif in COS structure, might be used to design and produce novel NLRP3 inhibitors as a lead compound.

Discovery of alantolactone as a naturally occurring NLRP3 inhibitor to alleviate NLRP3-driven inflammatory diseases in mice.

BACKGROUND AND PURPOSE: The NLR family pyrin domain-containing 3 (NLRP3) inflammasome is activated in many inflammatory conditions. So far, no low MW compounds inhibiting NLRP3 have entered clinical use. Identification of naturally occurring NLRP3 inhibitors may be beneficial to the design and development of compounds targeting NLRP3. Alantolactone is a phytochemical from a traditional Chinese medicinal plant with anti-inflammatory activity, but its precise target remains unclear. EXPERIMENTAL APPROACH: A bank of phytochemicals was screened for inhibitors of NLRP3-driven production of IL-1ß in cultures of bone-marrow-derived macrophages from female C57BL/6 mice. Models of gouty arthritis and acute lung injury in male C57BL/6J mice were used to determine the in vivo effects of the most potent compound. KEY RESULTS: Among the 150 compounds screened in vitro, alantolactone exhibited the highest inhibitory activity against LPS + ATP-induced production of IL-1ß in macrophages, suppressing IL-1ß secretion, caspase-1 activation and pyroptosis. Alantolactone directly bound to the NACHT domain of NLRP3 to inhibit activation and assembly of NLRP3 inflammasomes. Molecular simulation analysis suggested that Arg335 in NLRP3 was a critical residue for alantolactone binding, leading to suppression of NLRP3-NEK7 interaction. In vivo studies confirmed significant alleviation by alantolactone of two NLRP3-driven inflammatory conditions, acute lung injury and gouty arthritis. CONCLUSION AND IMPLICATIONS: The phytochemical alantolactone inhibited activity of NLRP3 inflammasomes by directly targeting the NACHT domain of NLRP3. Alantolactone shows great potential in the treatment of NLRP3-driven diseases and could lead to the development of novel NLRP3 inhibitors.

[Effect of the oil from ganoderma lucidum spores on pathological changes in the substantia nigra and behaviors of MPTP-treated mice].

OBJECTIVE: To investigate the oil from the spores of ganoderma lucidum, a rare Chinese herb, on the behaviors and pathological changes in the substantia nigra pars compacta (SNpc) in mouse models of Parkinson's disease (PD) induced by MPTP. METHODS: C57BL mice were divided into 3 groups, and the ganoderma spores oil + MPTP group were treated with ganoderma spores oil for 8 days, together with subcutaneous injection of MPTP (30 mg/kg) starting on the third day for 6 days; MPTP group were pretreated with normal saline before subcutaneous MPTP injection, and the normal control group received pretreatment with normal saline before subcutaneous normal saline injection. The behavioral changes of the mice in different groups were observed by pole test, dopamine and its metabolic products in the striatum determined by HPLC, tyrosine hydroxylase (TH) positive cells detected by immunofluorescence method, and expression of TH protein by Western blotting. RESULTS: The mice in the ganoderma spores oil + MPTP group presented significantly less involuntary movement of the limbs in the pole test than the mice in MPTP group. The levels of dopamine and DOPAC in the striatum of ganoderma spores oil-treated mice were increased as compared with those in MPTP group. The number of surviving TH-positive neurons in SNpc of mice in ganoderma spores oil + MPTP group was significantly greater than that in MPTP group, with also significantly increased TH protein expression. CONCLUSION: Ganoderma spores oil has neuroprotective effect for preventing doparminergic neuron from impairment by MPTP.