Curcumin Alleviates Epidermal Psoriasis-Like Dermatitis and IL-6/STAT3 Pathway of Mice

Abstract

Background: To further investigate why curcumin (CUR) can attenuate psoriasis-like dermatitis of mice.

Methods and results: Sixteen mice were randomized into four groups. The control group used carrier cream, and the model and the CUR group were applied with topical 5% imiquimod in the naked mice skin once a day for 6 days (62.5 mg/day/mice). Meanwhile, the control and model mice were given the same dose of saline by oral means, while mice in the CUR groups received oral drug doses of 50 and 100 mg/kg once a day for 6 days, respectively. CUR could largely improve imiquimod-induced lesions of mice. By using the ELISA and qPCR, we found that the protein and mRNA levels of epidermal TNF-α and IL-6 were inhibited by CUR. The phosphorylation levels of STAT3 and its downstream associated protein levels (eg, Cyclin D1, Bcl-2 and Pim1) in skin tissues of different groups were also inhibited by CUR. Furthermore, the results of immunohistochemistry also showed the repressed effect of CUR for the expression of TNF-α, IL-6 and p-STAT3 in psoriasis-like lesions of mice.

Conclusion: CUR can effectively ameliorate the featured lesions of psoriasis mice, which may be closely associated with the involvement of IL-6/STAT3 signaling.

Keywords: IL-6/STAT3; curcumin; inflammation; psoriasis.

Figure 1

(A) The morphology changes of the lesion skin in psoriasis mice. I, Control; II, Model; III, Cur 50 mg/kg; IV, Cur 100 mg/kg. The selected pictures were typical skin lesions in each group, N=4 per group.

Figure 2

PASI score of the lesion skin in psoriasis mice. (A–D) PASI score comparison between different groups, IMQ vs Cur, *P< 0.05, **P<0.01.

Figure 3

The histopathological changes of the lesion skin in psoriasis mice, and effect of CUR on the protein expression of TNF-α and IL-6 in lesion skin of the psoriasis mice. (A) Results of HE staining between groups. (B) IHC staining of TNF-α. (C) IHC staining of IL-6. I, Control; II, Model; III, CUR 50 mg/kg; IV, CUR 100 mg/kg. Scale bar, 50μm. The selected pictures were typical in each group, N=4 per group.

Figure 4

The epidermal protein and mRNA levels of TNF-α and IL-6 in psoriasis mice. (A and B) The harvested skin tissues were subjected to the ELISA kits for detecting protein levels of IL-6 and TNF-α. (C and D) The epidermal mRNA levels of mice were measured by qPCR. N=4 per group. *P< 0.05, **P<0.01, ***P<0.001.

Figure 5

Effect of CUR on the signaling pathway of STAT 3 in lesion skin of the psoriasis mice. (A) The protein levels of p-STAT3, T-STAT3, Cyclin D1, Bcl-2 and Pim1 were determined by Western blotting. (B–F) Gray statistics for each protein. p, phosphorylation; T, total. *P< 0.05, **P<0.01, ***P<0.01.

Figure 6

(A) The effect of CUR on the protein expression of p-STAT3 in lesion skin of the psoriasis mice. I, Control; II, Model; III, CUR 50 mg/kg; IV, CUR 100 mg/kg. Scale bar, 50μm. The selected images were typical skin lesions in each group, N=4 per group. (B) The structure of curcumin.