Anti-psoriatic Effects of Wannachawee Recipe on TNF-α- and IFN-γ-Induced Inflammatory Cytokine production in HaCaT Human Keratinocytes

Psoriasis is a common immune-mediated chronic inflammatory skin disease characterised by thick, erythema and scales. The psoriasis pathogenesis involves T cells activated via the IL-23/Th17 axis. Conventional treatments of psoriasis have adverse events that influence patients' adherence. Wannachawee Recipe (WCR) is known to be an effective folk remedy for psoriasis patients, however, preclinical evidence defining how WCR works is still lacking. This study investigated specific mechanisms underlying the therapeutic potential of WCR on anti-proliferation and anti-inflammatory effects in HaCaT human keratinocytes.

An anti-proliferative activity of WCR was measured by using SRB and WST-8 assays. The distribution of cell cycle phases was determined by cell cycle analysis. The TNF-α and IFN-γ induced mRNA expression of anti-inflammatory cytokines was detected by qRT-PCR, whereas the protein production of IL-17, IL-22 and IL-23 was confirmed by ELISA.

WCR exhibited a significant anti-proliferative effect (IC₅₀ 600 µg/mL). Three non-toxic concentrations of WCR (25, 50 and 75 µg/mL) and acitretin had no effect on the induction of cell cycle arrest, while methotrexate significantly induced S-phase arrest. The expression of IL-1b, IL-6, IL-8, IL-17, IL-22, IL-23 and TNF-α was dramatically decreased by acitretin and WCR treatment in TNF-α and IFN-γ-induced HaCaT cells. At the protein level, the treatment with 100 µg/mL of WCR and 6.5 µg/mL of acitretin significantly reduced the TNF-α and IFN-γ-stimulated cytokine production compared with only TNF-α and IFN-γ treatment group (p < 0.05).

WCR at low concentration (< 100 µg/mL) was proved to possess potent anti-inflammatory effects without toxicity or cell cycle arrest on the keratinocyte cells. This makes WCR a promising candidate for further investigation and development for psoriasis therapy. More sophisticated studies need to be verified to evaluate the precise mechanisms of action in relevant animal models to be certain that WCR is safe and effective for use in psoriasis patients.