1-3-dimethylthiourea and Asthma

Oxidative stress in allergic asthma may result from oxidase activity or proinflammatory molecules in pollens. Signaling via TLR4 and its adaptor Toll-IL-1R domain-containing adapter inducing IFN-β (TRIF) has been implicated in reactive oxygen species-mediated acute lung injury and in Th2 immune responses. We investigated the contributions of oxidative stress and TLR4/TRIF signaling to experimental asthma induced by birch pollen exposure exclusively via the airways. Mice were exposed to native or heat-inactivated white birch pollen extract (BPEx) intratracheally and injected with the antioxidants, N-acetyl-L-cysteine or dimethylthiourea, prior to sensitization, challenge, or all allergen exposures, to assess the role of oxidative stress and pollen-intrinsic NADPH oxidase activity in allergic sensitization, inflammation, and airway hyperresponsiveness (AHR). Additionally, TLR4 signaling was antagonized concomitantly with allergen exposure, or the development of allergic airway disease was evaluated in TLR4 or TRIF knockout mice. N-acetyl-L-cysteine inhibited BPEx-induced eosinophilic airway inflammation and AHR except when given exclusively during sensitization, whereas dimethylthiourea was inhibitory even when administered with the sensitization alone. Heat inactivation of BPEx had no effect on the development of allergic airway disease. Oxidative stress-mediated AHR was also TLR4 and TRIF independent; however, TLR4 deficiency decreased, whereas TRIF deficiency increased BPEx-induced airway inflammation. In conclusion, oxidative stress plays a significant role in allergic sensitization to pollen via the airway mucosa, but the pollen-intrinsic NADPH oxidase activity and TLR4 or TRIF signaling are unnecessary for the induction of allergic airway disease and AHR. Pollen extract does, however, activate TLR4, thereby enhancing airway inflammation, which is restrained by the TRIF-dependent pathway.

Topics: Acetylcysteine; Adaptor Proteins, Vesicular Transport; Animals; Asthma; Betula; Female; Interferon-beta; Mice; Mice, Inbred BALB C; Mice, Knockout; NADPH Oxidases; Oxidative Stress; Pollen; Reactive Oxygen Species; Th2 Cells; Thiourea; Toll-Like Receptor 4

Exposure to chlorine (Cl2) causes airway injury, characterized by oxidative damage, an influx of inflammatory cells and airway hyperresponsiveness. We hypothesized that Cl2-induced airway injury may be attenuated by antioxidant treatment, even after the initial injury.. Balb/C mice were exposed to Cl2 gas (100 ppm) for 5 mins, an exposure that was established to alter airway function with minimal histological disruption of the epithelium. Twenty-four hours after exposure to Cl2, airway responsiveness to aerosolized methacholine (MCh) was measured. Bronchoalveolar lavage (BAL) was performed to determine inflammatory cell profiles, total protein, and glutathione levels. Dimethylthiourea (DMTU;100 mg/kg) was administered one hour before or one hour following Cl2 exposure.. Mice exposed to Cl2 had airway hyperresponsiveness to MCh compared to control animals pre-treated and post-treated with DMTU. Total cell counts in BAL fluid were elevated by Cl2 exposure and were not affected by DMTU treatment. However, DMTU-treated mice had lower protein levels in the BAL than the Cl2-only treated animals. 4-Hydroxynonenal analysis showed that DMTU given pre- or post-Cl2 prevented lipid peroxidation in the lung. Following Cl2 exposure glutathione (GSH) was elevated immediately following exposure both in BAL cells and in fluid and this change was prevented by DMTU. GSSG was depleted in Cl2 exposed mice at later time points. However, the GSH/GSSG ratio remained high in chlorine exposed mice, an effect attenuated by DMTU.. Our data show that the anti-oxidant DMTU is effective in attenuating Cl2 induced increase in airway responsiveness, inflammation and biomarkers of oxidative stress.

Topics: Animals; Asthma; Chlorine; Dose-Response Relationship, Drug; Inhalation Exposure; Irritants; Lung; Male; Mice; Mice, Inbred BALB C; Respiratory Function Tests; Thiourea

Asthma and its exacerbation by air pollution are major public health problems. This investigation sought to more precisely model this disorder, which primarily affects children, by using very young mice. The study first attempted to create allergic airway hypersensitivity in neonatal mice and to determine if physiologic testing of airway function was possible in these small animals. Neonatal mice were sensitized by i.p. injection of ovalbumin (OVA, 5 microg) and alum (1 mg) at 3 and 7 d of age. One week later, mice were challenged by allergen nebulization (3% OVA in PBS, 10 min/d, d 14-16). OVA-exposed mice showed: (1) increased airway hyperresponsiveness (AHR) to methacholine by whole-body plethysmography; (2) eosinophilia in bronchoalveolar lavage (BAL) fluid; (3) airway inflammation using histopathology techniques; and (4) elevated serum anti-OVA immunoglobulin E. Hence, these neonatal mice were successfully sensitized and manifested "asthmatic" responses after allergen challenge. Experiments were conducted to investigate the effect of one surrogate for ambient air particles, residual oil fly ash (ROFA), on this juvenile asthma model. Aerosolized ROFA leachate (supernatant of 50 mg/ml, 30 min, on d 15) had no marked effect alone, but caused a significant increase in AHR and airway inflammation in OVA-sensitized and challenged mice. This synergistic effect was abrogated by the antioxidant dimethylthiourea (DMTU, 3 mg/kg mouse, i.p.). This model may be useful to study air pollution-mediated exacerbation of asthma in children.

Topics: Aerosols; Air Pollutants; Allergens; Animals; Animals, Newborn; Asthma; Bronchial Hyperreactivity; Bronchitis; Carbon; Coal Ash; Enzyme-Linked Immunosorbent Assay; Free Radical Scavengers; Immunoglobulin E; Mice; Mice, Inbred BALB C; Ovalbumin; Particulate Matter; Phenotype; Plethysmography; Serine Proteinase Inhibitors; Thiourea