Efficacy and Potential Mechanisms of Naringin in Atopic Dermatitis

Abstract

Atopic dermatitis (AD) is one of the most prevalent chronic inflammatory skin diseases. Topical treatments are recommended for all patients regardless of severity, making it essential to develop an effective topical AD treatment with minimal side effects; We investigated the efficacy of topical application of naringin in AD and explored the possible mechanisms using an AD mouse model induced by 1-chloro-2,4-dinitrobenzene (DNCB). Clinical, histological, and immunological changes related to AD and Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling proteins in the skin tissues were measured as outcomes; Naringin treatment resulted in a significant improvement in dermatitis severity score and reduced epidermal thickness and mast cell count in the skin (p < 0.05). Naringin also demonstrated the ability to inhibit DNCB-induced changes in interleukin (IL) 4, chemokine (C-C motif) ligand (CCL) 17, CCL22, IL1β, interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α) levels by quantitative real-time polymerase chain reaction (qRT-PCR) and IL13 by enzyme-linked immunosorbent assay (ELISA) (p < 0.05). Western blot results exhibited the decreased JAK1, JAK2, STAT1, STAT3, phospho-STAT3, and STAT6 expression in the naringin-treated groups (p < 0.05); The findings of this study suggest that topical naringin may effectively improve the symptoms of AD and could be used as a therapeutic agent for AD.

Keywords: atopic dermatitis; flavonoids; inflammation; naringin.

Figure 1

Chemical structures of (A) flavonoid and (B) naringin.

Figure 2

Schematic description of the experiment (n = 6 per group). DNCB, 1-chloro-2,4-dinitrobenzene.

Figure 3

(A) Clinical images of the ear and back at the end of the challenge period (day 16). (B) Graphs representing dermatitis severity and ear thickness assessment results. Values represent the mean ± SEM (n = 6). Data compared among multiple groups were analyzed using one-way analysis of variance. * p < 0.05, ** p < 0.01, *** p < 0.001 compared to the NC or DNCB-only group. DNCB, 1-chloro-2,4-dinitrobenzene; NC, normal control.

Figure 4

(A) Pathology images of H&E and toluidine blue staining in dorsal skin tissue samples. Mast cells are stained purple with toluidine blue. Original magnification = ×200, scale bar = 100 μm. (B) Graphs representing the epidermal thickness and the number of mast cells. Values are mean ± SEM (n = 6). Data compared among multiple groups were analyzed using one-way analysis of variance. *** p < 0.001 compared to the NC or DNCB-only group. H&E, hematoxylin and eosin; NC, normal control; DNCB, 1-chloro-2,4-dinitrobenzene.

Figure 5

Expressed mRNA level of (A) TNF-α, (B) IFN-γ, (C) IL4, (D) CCL17, (E) CCL22, (F) IL1β, (G) IL31, and (H) TSLP quantified by qRT-PCR and (I) IL13 by ELISA in dorsal skin tissues. The expression of each gene was normalized to that of Actb. Each qRT-PCR reaction was performed in triplicate. Values are mean ± SEM (n = 6). Data compared among multiple groups were analyzed using one-way analysis of variance. * p < 0.05, ** p < 0.01, *** p < 0.001 compared to the NC or DNCB-only group. CCL, chemokine C-C motif ligand; DNCB, 1-chloro-2,4-dinitrobenzene; IL, interleukin; INF-γ, interferon-gamma; NC, normal control; TNF-α, tumor necrosis factor-alpha; TSLP, thymic stromal lymphopoietin.

Figure 6

Expression of JAK–STAT proteins in dorsal skin tissues. Immunoblotting intensities were calculated with ImageJ software (version 1.8.0). Values are mean ± SEM (n = 6). Data compared among multiple groups were analyzed using one-way analysis of variance. * p < 0.05, ** p < 0.01, *** p < 0.001 compared to the NC or DNCB-only group. DNCB, 1-chloro-2,4-dinitrobenzene; JAK-STAT, Janus kinase-signal transducer and activator of transcription; NC, normal control; P-STAT3, phospho-STAT3.