BML-111 Modulates and Alleviates p38/MAPK Signaling Pathway and Th1/Th2/Th17 Cytokine Response in Murine Psoriasis-Like Dermatitis.

Background: Psoriasis is a prevalent cutaneous inflammatory disorder characterized by elevated keratinocyte inflammation. 5(S)-6(R)-7-trihydroxyheptanoic-acid-methyl-ester (BML-111), an established analogue of lipoxin A4, is known for its potent anti-inflammatory properties. However, the precise role of BML-111 within a murine psoriasis-like dermatitis model requires further clarification. This research aims to investigate the modulatory effects of BML-111 on inflammatory responses, the p38/mitogen-activated protein kinase (MAPK) signaling cascade, and T helper type 1 (Th1), Th2, and Th17 cell responses within the context of a murine psoriasis-like dermatitis model.

Methods: A psoriasis-like dermatitis model was established by applying 5% imiquimod (IMQ) cream to the backs of C57BL/6 mice, which were pretreated intraperitoneally with or without BML-111 prior to IMQ application. Hematoxylin-eosin staining was utilized to detect the pathological alterations of the murine dorsal skin tissue. Furthermore, the psoriasis area and severity index (PASI) scoring system was used to assess the dynamic cutaneous alterations in the mice. The levels of tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin (IL)-1β, IL-6, IL-4, and IL-17A in the murine serum samples were quantified by means of enzyme-linked immunosorbent assays (ELISA). Western blotting was conducted to detect the proteins of TNF-α, IL-1β, IL-6, phospho-p38 (p-p38), and p38 in murine skin tissues. Lastly, a flow cytometry analysis was executed to evaluate the expression of peripheral blood Th1/Th2/Th17 cell subsets.

Results: BML-111 attenuated IMQ-induced pathological changes in skin tissue of psoriasis-like dermatitis mice. BML-111 treatment substantially reduced TNF-α, IL-1β, IL-6, IFN-γ and IL-17A levels and elevated IL-4 levels in serum and skin lesion tissues of IMQ-induced mice (p < 0.01, p < 0.01, p < 0.01, p < 0.05, p < 0.05, p < 0.05, respectively). The ratio of Th1/Th17 cells in the peripheral blood of BML-111-treated mice was substantially diminished and the ratio of Th2 cells was substantially augmented (p < 0.05, p < 0.01, p < 0.001, respectively). Mechanistically, p-p38 protein level was substantially reduced in the skin tissues of BML-111-treated mice (p < 0.05). While, dehydrocorydaline (DHC, a p38/MAPK pathway agonists) reversed the reduction of p-p38 protein level induced by BML-111 treatment in psoriasis-like mice (p < 0.05).

Conclusion: BML-111 modulates the p38/MAPK signaling pathway and Th1/Th2/Th17 cytokine response, and alleviates psoriasis-like dermatitis in mice.