Abstract
BackgroundComplementary and alternative medicine (CAM) is becoming a popular treatment for modulating diverse immune disorders. Phellinus linteus (P. linteus) as one of the CAMs has been used to modulate cancers, inflammation and allergic activities. However, little evidence has been shown about its underlying mechanism of action by which it exerts a beneficial role in dermatological disease in vivo. In this study, we examined the immunomodulatory effects of P. linteus on experimental atopic dermatitis (AD) and elucidated its action mechanism.MethodsThe immunomodulatory effect of total extract of P. linteus on IgE production by human myeloma U266B1 cells was measured by ELISA. To further identify the effective components, P. linteus was fractionated into methanol soluble, water soluble and boiling water soluble extracts. Each extract was treated to U266B1 cells and primary B cells to compare their inhibitory effects on IgE secretion. To test the in vivo efficacy, experimental atopic dermatitis (AD) was established by alternative treatment of DNCB and house dust mite extract into BALB/c mice. Water soluble extract of P. linteus (WA) or ceramide as a positive control were topically applied to ears of atopic mouse every day for 2 weeks and progression of the disease was estimated by the following criteria: (a) ear thickness, clinical score, (b) serum total IgE, IgG and mite specific IgE level by ELSIA, (c) histological examination of ear tissue by H&E staining and (d) cytokine profile of total ear cells and CD4+ T cells by real time PCR and ELSIA.ResultsTreatment of total extracts of P. linteus to U266B1 inhibited IgE secretion. Among the diverse extracts of P. linteus, water soluble extract of P. linteus (WA) significantly reduced the IgE production in primary B cells and B cell line U266B1. Moreover, treatment of WA reduced AD symptoms such as ear swelling, erythema, and dryness and decreased recruitment of lymphocyte into the inflamed site. Interestingly WA treatment significantly reduced IgE level without affecting IgG levels and also down-regulated the levels of pathogenic cytokines (IL-4, IL-13, IL-12 and IFN-γ) and chemokines (CCL17 and CCL22) involved in AD development.ConclusionsOur study indicates that protective effect of water soluble extract of P. linteus in atopic dermatitis is mediated by inhibiting IgE production and expression of AD associated pathogenic cytokines as well as chemokines, suggesting the beneficial effect of P. linteus to modulate allergic skin disease.
Highlights
Complementary and alternative medicine (CAM) is becoming a popular treatment for modulating diverse immune disorders
Human U266B1 multiple myeloma cells were cultured in the presence of various concentrations of P. linteus extract for 72 hrs relative viable cells were measured by WST-1 assay (Figure 1A)
Cells were stimulated with LPS (10 μg/ml) and Interleukin 4 (IL-4) (5 ng/ml) in the presence of P. linteus extract or Phosphate buffer saline (PBS) as a control for 72 hrs and the levels of IgE production in the culture supernatant were measured by enzymelinked immunosorbent assay (ELISA)
Summary
Complementary and alternative medicine (CAM) is becoming a popular treatment for modulating diverse immune disorders. We examined the immunomodulatory effects of P. linteus on experimental atopic dermatitis (AD) and elucidated its action mechanism. Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by pruritic and eczematous skin lesions. IFN-γ increases the sensitivity of Fas-mediated apoptosis of keratinocytes, which is considered to be a key pathogenic event in eczematous dermatitis [5]. This immunological complexity associated with Th1/Th2 immune dysregulation makes it hard to properly modulate the AD symptoms. Topical steroid therapy is widely used for the treatment of AD patients, diverse side effects limits its application. Development of new treatment methods is being initiated with herbal medicine with similar effectiveness but less side effects [6]
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