Extract of Polygala tenuifolia Alleviates Stress-Exacerbated Atopy-Like Skin Dermatitis through the Modulation of Protein Kinase A and p38 Mitogen-Activated Protein Kinase Signaling Pathway

Int J Mol Sci. 2017 Jan 18;18(1):190. doi: 10.3390/ijms18010190.

Abstract

Atopic dermatitis (AD) and stress create a vicious cycle: stress exacerbates atopic symptoms, and atopic disease elicits stress and anxiety. Targeting multiple pathways including stress and allergic inflammation is, therefore, important for treating AD. In this study, we investigated the remedial value of Polygala tenuifolia Willd. (PTW) for treating immobilization (IMO) stress-exacerbated atopy-like skin dermatitis and its underlying mechanism. Trimellitic anhydride (TMA) was applied to dorsal skin for sensitization and subsequently both ears for eliciting T-cell-dependent contact hypersensitivity in mice, which underwent 2 h-IMO stress and PTW administration for the latter 6 and 9 days in the ear exposure period of TMA, respectively. To elicit in vitro degranulation of human mast cell line-1 (HMC-1), 10 µM substance P (SP) and 200 nM corticotrophin-releasing factor (CRF) were sequentially added with 48 h-interval. PTW extract (500 µg/mL) was added 30 min before CRF treatment. IMO stress exacerbated TMA-induced scratching behavior by 252%, and increased their blood corticosterone levels by two-fold. Treatment with 250 mg/kg PTW significantly restored IMO stress-exacerbated scratching behavior and other indicators such as skin inflammation and water content, lymph node weights, and serum histamine and immunoglobulin E (lgE) levels. Furthermore, it also reversed TMA-stimulated expression of tumor necrosis factor (TNF)-α and interleukin (IL)-4 mRNAs in ear tissues. PTW significantly inhibited SP/CRF-stimulated degranulation of HMC-1 cells, subsequent tryptase secretion, and protein kinase A (PKA) activity. PTW also selectively inhibited p38 mitogen-activated protein kinase (MAPK) phosphorylation in SP/CRF-treated HMC-1 cells. PTW significantly inhibited HMC-1 cell degranulation and alleviated IMO stress-exacerbated atopic dermatitis symptoms by modulating the PKA/p38 MAPK signaling pathway.

Keywords: Polygala tenuifolia Willd.; atopic dermatitis; corticotrophin-releasing factor; immobilization stress; trimellitic anhydride.

MeSH terms

  • Animals
  • Behavior, Animal
  • Cell Line
  • Chromatography, High Pressure Liquid
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Dermatitis, Atopic / blood
  • Dermatitis, Atopic / complications
  • Dermatitis, Atopic / drug therapy*
  • Ear / pathology
  • Humans
  • Immobilization
  • Immunoglobulin E / blood
  • Interleukin-4 / genetics
  • Interleukin-4 / metabolism
  • MAP Kinase Signaling System* / drug effects
  • Male
  • Mast Cells / metabolism
  • Mice
  • Mice, Inbred BALB C
  • Phytochemicals / analysis
  • Phytotherapy
  • Plant Extracts / pharmacology
  • Plant Extracts / therapeutic use*
  • Polygala / chemistry*
  • Protein Kinase C / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Skin / pathology
  • Spectrometry, Mass, Electrospray Ionization
  • Stress, Psychological / blood
  • Stress, Psychological / complications
  • Stress, Psychological / drug therapy*
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism
  • Water
  • p38 Mitogen-Activated Protein Kinases / metabolism*

Substances

  • Phytochemicals
  • Plant Extracts
  • RNA, Messenger
  • Tumor Necrosis Factor-alpha
  • Water
  • Interleukin-4
  • Immunoglobulin E
  • Cyclic AMP-Dependent Protein Kinases
  • Protein Kinase C
  • p38 Mitogen-Activated Protein Kinases