Neutrophil extracellular traps (NETs) have been implicated in the development of certain immune-mediated diseases, but their role in psoriasis has not been clearly defined. Human β-defensin-2 (HBD-2) is an important antimicrobial peptide overexpressed in psoriasis epidermis. We evaluated whether the amount of NETs is increased in psoriasis and determined the effect of NETs on HBD-2 production in epidermal keratinocytes. Using fluorescent microscopy, we found that patients with psoriasis (n = 48) had higher amount of NETotic cells in their peripheral blood compared to healthy controls (n = 48) and patients with eczema (n = 35). Psoriasis sera showed increased ability to induce NET formation in control neutrophils but normal NET degradation ability. The amount of NETs in the peripheral blood correlated with psoriasis disease severity. NETosis was also observed in the majority (18 of 20) of psoriasis skin specimens. Furthermore, NETs induced HBD-2 mRNA and protein production in keratinocytes, and immunohistochemical analysis confirmed strong expression of HBD-2 in psoriasis lesional skin. In summary, NET formation is increased in peripheral blood and lesional skin of psoriasis patients and correlates with disease severity. Additionally, NET-induced HBD-2 production may provide a novel mechanism for the decreased susceptibility of psoriasis plaques to microbial infections.

Pterostilbene is a methoxylated derivative of resveratrol originated from natural sources. We investigated the antibacterial activity of pterostilbene against drug-resistant Staphylococcus aureus and the feasibility of using it to treat cutaneous bacteria. The antimicrobial effect was evaluated using an in vitro culture model and an in vivo mouse model of cutaneous infection. The minimum inhibitory concentration (MIC) assay demonstrated a superior biocidal activity of pterostilbene compared to resveratrol (8~16-fold) against methicillin-resistant S. aureus (MRSA) and clinically isolated vancomycin-intermediate S. aureus (VISA). Pterostilbene was found to reduce MRSA biofilm thickness from 18 to 10 μm as detected by confocal microscopy. Pterostilbene showed minimal toxicity to THP-1 cells and was readily engulfed by the macrophages, facilitating the eradication of intracellular MRSA. Pterostilbene exhibited increased skin absorption over resveratrol by 6-fold. Topical pterostilbene application improved the abscess formation produced by MRSA by reducing the bacterial burden and ameliorating the skin architecture. The potent anti-MRSA capability of pterostilbene was related to bacterial membrane leakage, chaperone protein downregulation, and ribosomal protein upregulation. This mechanism of action was different from that of resveratrol according to proteomic analysis and molecular docking. Pterostilbene has the potential to serve as a novel class of topically applied agents for treating MRSA infection in the skin while demonstrating less toxicity to mammalian cells.

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Resveratrol (RES), a well-known antioxidant and anti-inflammatory compound, is abundant in red wine and exerts numerous pharmacological effects, including hepatoprotection and cadioprotection. Unfortunately, RES is restricted in clinical application due to poor dissolution property and adsorption. In addition, red wine as a supplement for preventing disease is not recommended for patients with alcohol-related disorders. To address these limitations, we successfully developed a novel RES nanoparticle system (RESN) and demonstrated that RESN could circumvent the physicochemical drawbacks of raw RES with respect to dissolution, such as the reduction of particle size, amorphous transformation, and hydrogen-bond formation. In addition, we employed an animal model of CCl₄-induced hepatotoxicity to estimate the potential of the nanoparticle formulation to improve the hepatoprotective effect of orally administered RES. Our results demonstrated that RESN can diminish liver function markers (aspartate aminotransferase and alanine aminotransferase) by decreasing hepatocyte death due to CCl₄-induced hepatotoxicity in rats, when compared with RES administration. The effect was achieved by reducing oxidative stress (decreased reactive oxygen species and lipid peroxidation) and lowering inflammatory cytokines (decreased tumor necrosis factor-α and interleukin 1β) and protein expression (cyclooxygenase-2, inducible nitric oxide synthase, cytosolic phospholipase A2, and caspase-3). In conclusion, enhancement of the dissolution of RES through a nanoparticle engineering process can result in increased hepatoprotective effects mediated by antioxidant and anti-inflammatory activities. Consequently, we suggest that RESN deserves further study, perhaps in prophylaxis of chronic liver diseases.

Kaempferol (KAE) is a strong antioxidant flavonoid compound, but its clinical application is limited by quantity and poor dissolution property. However, the dissolution mechanism of a kaempferol nanoparticle formulation (KAEN) has not yet been elucidated. The aim of the present study was therefore to use a nanoparticle engineering process to resolve the dissolution problem. Our data indicated that KAEN effectively increased the dissolution percentage by particle size reduction, high encapsulation efficiency, amorphous transformation, and hydrogen-bond formation with excipients. In addition, we used several different antioxidant activity assays to evaluate KAE and KAEN. The data indicated that KAEN retained potent antioxidant activity after the nanoparticle engineering process and showed better antioxidant activity than KAE dissolved in water (P < 0.05). According to these findings, we concluded that KAEN could be a low-dose alternative to KAE in health food and future clinical research.

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