Study on Anti-Inflammatory Effect and Major Anti-Inflammatory Components of PSORI-CM02 by Zebrafish Model

Astilbin inhibited neutrophil extracellular traps in gouty arthritis through suppression of purinergic P2Y6 receptor

BACKGROUND

Gouty arthritis (GA), a common inflammatory condition triggered by monosodium urate crystal accumulation, often necessitates safer treatment alternatives due to the limitations of current therapies. Astilbin, a flavonoid from Smilax glabra Roxb, has demonstrated potential in traditional Chinese medicine for its anti-inflammatory properties. However, the anti-GA effect and its underlying mechanism have not been fully elucidated.

PURPOSE

This study aimed to investigate the therapeutic potential of astilbin in GA, focusing on its effects on neutrophil extracellular traps (NETs), as well as the potential molecular target of GA both in vitro and in vivo.

STUDY DESIGN

Firstly, astilbin inhibited the citrullinated histone H3 (Cit h3) protein levels and reduced the NETs formation in neutrophils stimulated by monosodium urate (MSU). Secondly, we wondered the effect of astilbin on migration of neutrophils and dimethyl-sulfoxide (DMSO)-differentiated HL-60 (dHL-60) cells under the stimulation of MSU. Then, the effect of astilbin on suppressing NETs through purinergic P2Y6 receptor (P2Y6R) and Interlukin-8 (IL-8)/ CXC chemokine receptor 2 (CXCR2) pathway was investigated. Also, the relationship between P2Y6R and IL-8/CXCR2 was explored in dHL-60 cells under stimulation of MSU. Finally, we testified the effect of astilbin on reducing NETs in GA through suppressing P2Y6R and then down-regulating IL-8/CXCR2 pathway.

METHODS

MSU was used to induce NETs in neutrophils and dHL-60 cells. Real-time formation of NETs and migration of neutrophils were monitored by cell living imaging with or without MSU. Then, the effect of astilbin on NETs formation, P2Y6R and IL-8/CXCR2 pathway were detected by immunofluorescence (IF) and western blotting. P2Y6R knockdown dHL-60 cells were established by small interfering RNA to investigate the association between P2Y6R and IL-8/CXCR2 pathway. Also, plasmid of P2Y6R was used to overexpress P2Y6R in dHL-60 cells, which was employed to explore the role of P2Y6R in astilbin inhibiting NETs. Within the conditions of knockdown and overexpression of P2Y6R, migration and NETs formation were assessed by transmigration assay and IF staining, respectively. In vivo, MSU-induced GA mice model was established to assess the effect of astilbin on inflammation by haematoxylin-eosin and ELISA. Additionally, the effects of astilbin on neutrophils infiltration, NETs, P2Y6R and IL-8/CXCR2 pathway were analyzed by IF, ELISA, immunohistochemistry (IHC) and western blotting.

RESULTS

Under MSU stimulation, astilbin significantly suppressed the level of Cit h3 and NETs formation including the fluorescent expressions of Cit h3, neutrophils elastase, myeloperoxidase, and intra/extracellular DNA. Also, results showed that MSU caused NETs release in neutrophils as well as a trend towards recruitment of dHL-60 cells to MSU. Astilbin could markedly decrease expressions of P2Y6R and IL-8/CXCR2 pathway which were upregulated by MSU. By silencing P2Y6R, the expression of IL-8/CXCR2 pathway and migration of dHL-60 cells were inhibited, leading to the suppression of NETs. These findings indicated the upstream role of P2Y6R in the IL-8/CXCR2 pathway. Moreover, overexpression of P2Y6R was evidently inhibited by astilbin, causing a downregulation in IL-8/CXCR2 pathway, migration of dHL-60 cells and NETs formation. These results emphasized that astilbin inhibited the IL-8/CXCR2 pathway primarily through P2Y6R. In vivo, astilbin administration led to marked reductions in ankle swelling, inflammatory infiltration as well as neutrophils infiltration. Expressions of P2Y6R and IL-8/CXCR2 pathway were evidently decreased by astilbin and P2Y6R inhibitor MRS2578 either alone or in combination. Also, astilbin and MRS2578 showed notable effect on reducing MSU-induced NETs formation and IL-8/CXCR2 pathway whether used alone or in combination, parallelly demonstrating that astilbin decreased NETs formation mainly through P2Y6R.

CONCLUSION

This study revealed that astilbin suppressed NETs formation via downregulating P2Y6R and subsequently the IL-8/CXCR2 pathway, which evidently mitigated GA induced by MSU. It also highlighted the potential of astilbin as a promising natural therapeutic for GA.

Molecular Networking-Driven Discovery of Antibacterial Perinadines, New Tetracyclic Alkaloids from the Marine Sponge-Derived Fungus Aspergillus sp

Two rare tetracyclic skeleton alkaloids named perinadines B and C (1 and 2) were isolated as mixtures of epimers from the marine-derived Aspergillus sp. LS116 driven by molecular networking. The planar structures of 1 and 2 were characterized by comprehensive spectroscopic data. Additionally, compounds 1 and 2 showed moderate in vitro antibacterial activity against Bacillus subtilis with minimum inhibitory concentration values of 32 and 64 μg/mL, respectively. Besides, both of the compounds were evaluated for anti-inflammatory activities in an in vivo zebra fish model.

Kaempferol-3-O-Glucuronide Ameliorates Non-Alcoholic Steatohepatitis in High-Cholesterol-Diet-Induced Larval Zebrafish and HepG2 Cell Models via Regulating Oxidation Stress

NAFLD (non-alcoholic fatty liver disease) is one of the most prominent liver diseases in the world. As a metabolic-related disease, the development of NAFLD is closely associated with various degrees of lipid accumulation, oxidation, inflammation, and fibrosis. Ilex chinensis Sims is a form of traditional Chinese medicine which is used to treat bronchitis, burns, pneumonia, ulceration, and chilblains. Kaempferol-3-O-glucuronide (K3O) is a natural chemical present in Ilex chinensis Sims. This study was designed to investigate the antioxidative, fat metabolism-regulating, and anti-inflammatory potential of K3O. A high-cholesterol diet (HCD) was used to establish steatosis in larval zebrafish, whereby 1mM free fatty acid (FFA) was used to induce lipid accumulation in HepG2 cells, while H₂O₂ was used to induce oxidative stress in HepG2. The results of this experiment showed that K3O reduced lipid accumulation and the level of reactive oxygen species (ROS) both in vivo (K3O, 40 μM) and in vitro (K3O, 20 μM). Additionally, K3O (40 μM) reduced neutrophil aggregation in vivo. K3O (20 μM) also decreased the level of malondialdehyde (MDA) and significantly increased the level of glutathione peroxidase (GSH-px) in both the HCD-induced larval zebrafish model and H₂O₂-exposed HepG2 cells. In the mechanism study, keap1, nrf2, tnf-α, and il-6 mRNA were all significantly reversed by K3O (20 μM) in zebrafish. Changes in Keap1 and Nrf2 mRNA expression were also detected in H₂O₂-exposed HepG2 cells after they were treated with K3O (20 μM). In conclusion, K3O exhibited a reduction in oxidative stress and lipid peroxidation, and this may be related to the Nrf2/Keap1 pathway in the NAFLD larval zebrafish model.