Ulmus pumila Linné (Ulmi) Extract Attenuates Inflammatory Responses in Atopic Dermatitis by Modulating Lipid...

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by oxidative stress and impaired skin barrier function. These pathological features contribute to persistent inflammation and symptom exacerbation, highlighting the need for therapies that can both reduce oxidative stress and modulate inflammatory pathways.

Ulmus pumila Linné (Ulmi) was prepared via hot water extraction and tested for cytotoxicity, antioxidant activity, and anti-inflammatory effects in HaCaT keratinocytes stimulated with tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ). In vivo efficacy was assessed using a 2,4-dinitrochlorobenzene (DNCB)-induced AD model in SKH-1 hairless mice. Bioactive compounds were identified using liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS/MS), and molecular docking analysis was performed to evaluate the binding affinity of these compounds to aldehyde dehydrogenase 2 (ALDH2).

3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays confirmed that Ulmi was safe at concentrations up to 400 μg/mL. In TNF-α/IFN-γ-stimulated HaCaT cells, Ulmi significantly upregulated ALDH2 expression in a dose-dependent manner and reduced reactive oxygen species (ROS) production. The extract also suppressed pro-inflammatory mediators such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), while inhibiting the activation of nuclear factor kappa B (NF-κB) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathways. In the AD mouse model, Ulmi treatment improved clinical skin scores, reduced epidermal thickness, and decreased inflammatory markers compared to untreated controls. LC-QTOF-MS/MS analysis identified eight bioactive compounds, with procyanidin B2, catechin, and epicatechin as major constituents. Molecular docking revealed that procyanidin B2 had the strongest binding affinity to ALDH2 (-9.5 kcal/mol).

These findings demonstrate that Ulmi effectively ameliorates AD-like symptoms through ALDH2-mediated antioxidant mechanisms and anti-inflammatory effects. The results suggest that Ulmi may serve as a promising natural therapeutic agent for the management of atopic dermatitis.