Propolis suppresses atopic dermatitis through targeting the MKK4 pathway.

Area of Science:

• Immunology
• Dermatology
• Natural Products Chemistry

Background:

• Propolis, a bee-derived resin, is recognized for its bioactivities.
• Its therapeutic potential for atopic dermatitis (AD) is largely unexplored.
• AD is a chronic inflammatory skin condition with impaired skin barrier function.

Purpose of the Study:

• To investigate the efficacy of propolis in treating atopic dermatitis (AD).
• To identify the active compound in propolis responsible for therapeutic effects.
• To elucidate the molecular mechanisms underlying propolis action in AD.

Main Methods:

• In vitro studies using HaCaT keratinocytes to assess cytokine and chemokine secretion, and barrier protein expression.
• Ex vivo analysis on AD-like human skin samples.
• In vivo studies using DNCB-induced AD mouse models to evaluate clinical symptoms, barrier function, and gene expression.
• Chemical analysis to identify active compounds, followed by mechanistic studies targeting MKK4.

Main Results:

• Propolis inhibited key inflammatory mediators (IL-6, IL-8, MCP-1, MDC) and restored skin barrier proteins (filaggrin, involucrin) in vitro and in ex vivo skin models.
• Oral propolis administration in mice attenuated AD symptoms, improved skin barrier, reduced scratching, and normalized AD-related gene expression.
• Caffeic acid phenethyl ester (CAPE) was identified as the active compound.
• Both propolis and CAPE directly targeted MKK4.

Conclusions:

• Propolis demonstrates significant therapeutic potential for atopic dermatitis (AD).
• The mechanism involves inhibition of inflammatory pathways and restoration of skin barrier function, mediated by CAPE targeting MKK4.
• Propolis can be considered a functional food agent for AD management.