Silymarin exerts antipsoriatic effects against imiquimod-induced psoriasis in mice via NF-kB/TLR4 signaling pathway

Abstract

Objectives: Psoriasis is an autoimmune disease that mainly affects the skin and joints, which is mediated via T-cells. Several factors contribute to its pathogenesis, including genetic and environmental triggers, as well as intrinsic immune processes that lead to an autoimmune response. Silymarin, a flavonoid complex extracted from Silybum marianum, exhibits anti-inflammatory, immunostimulatory, and anti-oxidant properties, rendering it a viable candidate for treating psoriasis. This study aimed to investigate the effect of silymarin on imiquimod (IMQ) induced psoriasis-like skin lesions in male mice applied as a cream for seven consecutive days (1 mg per mouse).

Materials and methods: Thirty-five male mice were assigned to seven groups (n=5 per group): (I) control group, (II) IMQ group, (III-V) oral silymarin groups (30, 60, and 120 mg/kg), (VI) topical betamethasone group, and (VII) topical silymarin 2% group.

Results: Silymarin, both orally and topically, significantly reduces erythema, thickness, and scaling induced by IMQ after seven days of treatment. The treatment also reversed the increase in spleen weight/body weight ratio. Immunofluorescence analysis revealed that silymarin reduced the expression of nuclear factor κB (NF-κB) (P<0.01) and toll-like receptor 4 (TLR4) (P<0.01) compared to the IMQ group.

Conclusion: These findings suggest that silymarin effectively alleviates psoriasis lesions by reducing inflammation and modulating the TLR4/ NF-κB signaling pathway.

Keywords: Imiquimodm; Inflammation; Male mice; Psoriasis; Silymarin.

Figure 1

Results of topical and oral silymarin effect on (A) erythema; (B) thickness; (C) scales; (D) PASI score of each group following IMQ-induced psoriasis in mice

Figure 2.

Clinical phenotypic characteristics changes after 7 days in mice

Figure 3

Oral and topical silymarin effect on spleen/body weight and spleen morphology of each group following IMQ-induced psoriasis in mice

Figure 4

(A) TLR4 fluorescence immunostaining of the skin (× 40) of the mice, B) the optical intensity of IHC assay results using image

Figure 5

(A) p65 NF-κB fluorescence immunohistochemistry staining (IHC) (× 40) of the skin of the mice, (B) Optical intensity of IHC assay results using image