Neutrophil extracellular traps (NETs) formation is a key process in inflammatory diseases like gout, but the underlying molecular mechanisms remain incompletely understood. This study aimed to establish a model to examine the formation of NETs induced by monosodium urate (MSU) and phorbol 12-myristate 13-acetate (PMA) and to elucidate their molecular pathways. Laser confocal microscopy was used to visualize NET formation, while flow cytometry was employed to detect reactive oxygen species (ROS) production. The microstructure of neutrophils was observed by transmission electron microscopy, and the expression of key proteins was determined by Western blotting. Additionally, the effect of various inhibitors targeting the MAPK signaling pathway on NET formation was evaluated. They include the Ras inhibitor Salirasib, Raf inhibitor Vemurafenib, ERK inhibitor PD98059, and p38 MAPK inhibitor SB203580, as well as NADPH oxidase inhibitor DPI and neutrophil elastase inhibitor Alvelestat. The results showed that MSU and PMA triggered significant NET formation, which was accompanied by increased ROS levels, lactate dehydrogenase release, dsDNA, and IL-8. Notably, selective MAPK pathway inhibitors and DPI and Alvelestat, except for SB203580, effectively down-regulated these indicators. These data indicated that the activation of a signaling pathway involving Ras-Raf-ERK, which is dependent on ROS, is crucial for the induction of NET formation by MSU and PMA. Given the involvement of NETs in multiple pathologies, our findings could potentially serve as molecular targets for the intervention and treatment of crystal-related diseases, especially for gout.

Gouty arthritis (GA) is a frequent inflammatory disease characterized by pain, swelling, and stiffness of joints. Neoastilbin is a flavonoid isolated from the rhizome of Smilax glabra, which possesses various anti-inflammatory effects. However, the mechanism of neoastilbin in treating GA has not yet been clarified. Thus, this study was to investigate the protective effects of neoastilbin in both monosodium urate (MSU) stimulated THP-1-derived macrophages and the animal model of GA by injecting MSU into the ankle joints of mice. The levels of key inflammatory cytokines in MSU stimulated THP-1-derived macrophages were detected by enzyme-linked immunosorbent assay (ELISA) kits. Protein expressions of nuclear factor kappa B (NF-κB) and NOD-like receptor protein 3 (NLRP3) inflammasome pathways were further detected by Western blotting. In addition, swelling degree of ankle joints, the levels of inflammatory factors, infiltration of inflammatory cells and the expressions of related proteins were determined. Swelling degree and histopathological injury in ankle joints of MSU-injected mice were significantly decreased after being treated with neoastilbin. Moreover, neoastilbin significantly diminished the secretion of interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), suppressing the activation of NF-κB and NLRP3 inflammasome pathways in both MSU stimulated THP-1-derived macrophages and the mouse model of GA. In summary, neoastilbin could alleviate GA by inhibiting the NF-κB and NLRP3 inflammasome pathways, which provided some evidence for neoastilbin as a promising therapeutic agent for GA treatment.

Myricetin (Myr) is a phytochemical with many functional properties. However, its hydrophobicity, low bioavailability, and stability limit its application. In this study, octadecanoate oat β-glucan (OGE) was synthesized and gained recognition as a self-assembled micelle forming a polymer with a critical micelle concentration (CMC) of 59.4 μg/mL. The Myr-loaded OGE micelle was then prepared and characterized by dynamic light scattering (DLS), transmission electron microscope (TEM), X-ray diffractometer (XRD), and Fourier-transform infrared spectroscopy (FT-IR) spectra. The water solubility of Myr was greatly enhanced by forming the Myr/OGE inclusion complex. Consequently, compared to free Myr, the retention of Myr in Myr-loaded OGE micelle was effectively increased during the intestinal digestion phase, and its antioxidant activity was also improved. Overall, our findings demonstrated the potential applications of OGE polymer for the development of prospective micelle in health food, cosmetics, and pharmaceutical fields because they can aid in the delivery of hydrophobic functional compounds like Myr.

Background: Polygonatum sibiricum (PS), a perennial herbaceous plant belonging to the Liliaceae family, is widely distributed in China and other East Asian countries. PS has been used as food and medicine for thousands of years, and its rhizomes are rich in Polygonatum sibiricum polysaccharides (PSP), which exhibit various bioactivities, yet their structural features and therapeutic mechanisms against ulcerative colitis (UC) remain unclear. Methods: A homogeneous polysaccharide, PSP-1b (57.45 kDa), was isolated from the rhizomes of PS via ion-exchange and gel filtration chromatography and structurally characterized using chromatographic and spectroscopic methods. In vivo, its effects were evaluated in a dextran sulfate sodium (DSS)-induced mouse model of UC, while in vitro mechanisms were explored using macrophages stimulated with lipopolysaccharide (LPS) and neutrophil extracellular traps (NETs). Results: PSP-1b was identified as a neutral polysaccharide with minimal branching. Its primary structural backbone was largely composed of →4)-β-D-Galp-(1→ residues. A portion of these backbone residues was substituted at the O-6 position by side chains primarily composed of β-D-Galp-(1→ units. In vivo, PSP-1b significantly alleviated DSS-induced colitis by reducing inflammatory cytokine secretion, suppressing colonic macrophage infiltration, and reversing neutrophil extracellular traps (NETs) deposition. In vitro, PSP-1b directly interacted with TLR4, inhibited the MAPK/NF-κB signaling pathway, and attenuated LPS- and NET-induced macrophage polarization and inflammation. Conclusions: PSP-1b as a promising candidate for functional foods or therapeutic agents targeting inflammatory bowel disease.

Background/Objectives: Gouty arthritis (GA) is an inflammatory disease caused by increased purine metabolism. The limitations of current anti-GA therapies remain a major challenge. Astilbin, the main flavonoid in Smilax glabra Roxb., was found to exert potential anti-GA effects in our previous study. Methods: In this study, a mouse model of monosodium urate (MSU)-induced arthritis and an inflammatory model using mouse bone marrow-derived macrophages (BMDMs) were established. Results: Our data showed that astilbin reduced MSU-induced joint swelling and inflammatory infiltration in mice, restored lipopolysaccharide (LPS)/MSU-induced reductions in cell viability, and inhibited the expression levels of inflammatory factors IL-1β, IL-6 and TNF-α. Further studies showed that astilbin significantly reduced MSU-induced increases in NLRP3 and P-p65 protein levels, as well as the expression of ASC, P-IKKα, P-IκBα, and cleaved-caspase-1. Conclusions: This study suggests that astilbin may be a promising natural product for the treatment of GA by inhibiting the activation of the NLRP3 inflammasome and NF-κB signaling pathway.