Alcohol Extract of Angelicae Pubescentis Radix Treats Gouty Arthritis Induced by MSU via NLRP3/ASC/Caspase-1 Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the efficacy and mechanism of the alcohol extract DH50 of Angelicae Pubescentis Radix in treating gouty arthritis induced by monosodium urate （MSU） crystals in vivo and in vitro. MethodFifty male SD rats were randomly assigned into five groups （n=10）： a normal group， a model group， a dexamethasone （DXMS， 0.07 mg·kg-1） group， and low- （DH50-D， 9 mg·kg-1） and high-dose （DH50-G， 18 mg·kg-1） DH50 groups. The rats in the normal group and model group were administrated with the same amount of pure water. On day 5， the gouty arthritis model was established by injecting MSU into the right ankle joint of rats. The toe volume and joint inflammation index were measured 4， 8， 24， and 48 h after modeling. The pathological changes of the synovial tissue were detected by hematoxylin-eosin （HE） staining. Enzyme-linked immunosorbent assay （ELISA） was employed to measure the levels of tumor necrosis factor-alpha （TNF-α）， interleukin （IL）-1β， and IL-6 in the synovial tissue. Western blot was employed to measure the protein levels of NOD-like receptor protein 3 （NLRP3）， cysteine-aspartic protease-1 （Caspase-1）， apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain （ASC）， IL-1β， and cyclooxygenase-2 （COX-2） in the synovial tissue. Furthermore， the cell inflammation model was established with RAW264.7 cells stimulated with MSU （75 mg·L-1）. The cell experiments were carried out with 6 groups： a normal group， a model group， a positive drug （DXMS， 100 μmol·L-1） group， and low- （DH50-D， 25 mg·L-1）， medium- （DH50-Z， 50 mg·L-1）， and high-dose （DH50-G， 100 mg·L-1） DH50 groups. Methyl thiazolyl tetrazolium （MTT） assay was employed to determine the cell viability， ELISA to determine the content of TNF-α in the supernatant of cell culture， and Western blot to determine the protein levels of NLRP3， cleaved Caspase-1， IL-1β， TNF-α， and COX-2. ResultCompared with the normal group， the rat model group showed increased toe swelling degree and joint inflammatory index （P<0.01）， serious infiltration of the synovium， elevated levels of inflammatory cytokines in the tissue homogenate （P<0.01）， and up-regulated protein levels of NLRP3， Caspase-1， ASC， IL-1β， and COX-2 （P<0.05， P<0.01）. Compared with the rat model group， low- and high-dose DH50 mitigated the toe swelling degree， decreased the joint inflammatory index， alleviated the inflammatory infiltration， lowered the levels of inflammatory cytokines in the tissue homogenate （P<0.01）， and down-regulated the expression of related proteins （P<0.05， P<0.01）. Compared with the normal group， the cell model group showed elevated level of TNF-α in the supernatant （P<0.01） and up-regulated protein levels of NLRP3， cleaved Caspase-1， IL-1β， TNF-α， and COX-2 （P<0.05）. Compared with the model group， low， medium， and high doses of DH50 lowered the level of TNF-α in the supernatant of cell culture in a dose-dependent manner and down-regulated the expression of related proteins （P<0.05， P<0.01）. ConclusionDH50 can mitigate gouty arthritis both in vitro and in vivo by inhibiting the activation of NLRP3 inflammasomes and the production of inflammatory cytokines.