Inhibitory effects of l-theanine on airway inflammation in ovalbumin-induced allergic asthma

Food Chem Toxicol. 2017 Jan;99:162-169. doi: 10.1016/j.fct.2016.11.032. Epub 2016 Nov 29.

Abstract

l-theanine, a water-soluble amino acid isolated from green tea (Camellia sinensis), has anti-inflammatory activity, antioxidative properties, and hepatoprotective effects. However, the anti-allergic effect of l-theanine and its underlying molecular mechanisms have not been elucidated. In this study, we investigated the protective effects of l-theanine on asthmatic responses, particularly airway inflammation and oxidative stress modulation in an ovalbumin (OVA)-induced murine model of asthma. Treatment with l-theanine dramatically attenuated the extensive trafficking of inflammatory cells into bronchoalveolar lavage fluid (BALF). Histological studies revealed that l-theanine significantly inhibited OVA-induced mucus production and inflammatory cell infiltration in the respiratory tract and blood vessels. l-theanine administration also significantly decreased the production of IgE, monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-4, IL-5, IL-13, tumor necrosis factor-alpha (TNF-α), and interferon-gamma in BALF. The lung weight decreased with l-theanine administration. l-theanine also markedly attenuated the OVA-induced generation of reactive oxygen species and the activation of nuclear factor kappa B (NF-κB) and matrix metalloprotease-9 in BALF. Moreover, l-theanine reduced the TNF-α-induced NF-κB activation in A549 cells. Together, these results suggest that l-theanine alleviates airway inflammation in asthma, which likely occurs via the oxidative stress-responsive NF-κB pathway, highlighting its potential as a useful therapeutic agent for asthma management.

Keywords: Airway inflammation; Cytokine; L-theanine; NF-κB; Ovalbumin.

MeSH terms

  • Animals
  • Anti-Allergic Agents / pharmacology*
  • Anti-Asthmatic Agents / pharmacology*
  • Anti-Inflammatory Agents / pharmacology
  • Asthma / chemically induced
  • Asthma / drug therapy*
  • Asthma / immunology
  • Blotting, Western
  • Cytokines / metabolism
  • Female
  • Glutamates / pharmacology*
  • Inflammation / chemically induced
  • Inflammation / drug therapy*
  • Inflammation / immunology
  • Mice
  • Mice, Inbred ICR
  • Ovalbumin / toxicity*
  • Respiratory System / drug effects*

Substances

  • Anti-Allergic Agents
  • Anti-Asthmatic Agents
  • Anti-Inflammatory Agents
  • Cytokines
  • Glutamates
  • theanine
  • Ovalbumin