Carvalho, AN; Annoni, R; Hebeda, CB; Torres, LHL; Durao, ACS; Almeida, FM; Dolhnikoff, M; Marcourakis, T; Farsky, SHP; Saldiva, PHN; Trevisan, MS; Mauad, T
Rationale: Annacardium occidentale L. (cashew) is a tropical tree indigenous to Brazil. Products from cashew have been used for industrial application (juice, jams, syrups, paints, gasoline stabilization) as well as in folk medicine to treat gastrointestinal disorders, mouth ulcers, and throat problems. Anacardic acids extracted from the cashew nut-shell liquid present several biological activities such inhibition of the lipooxigenases and of the NF-κB, antioxidant properties, antibacterial and gastroprotective activities. However, there are no data on its effects on the respiratory system. The aim of this study was to investigate the effects of anacardic acids on diesel exhaust particles (DEP)-induced lung inflammation in a mice model.
Methods: Lung inflammation in male BALB/c mice was induced by 20 days intranasal instillation of 50 µg DEP collected from pipe of circulating buses in São Paulo City, control group received 10 µL of saline solution (Ctrl). Ten days before DEP instillation, animals were treated orally by 30 days with 50 mg/Kg (A50), 150 mg/Kg (A150) or 250 mg/Kg (A250) of anacardic acids from cashew nut-shell oil. Negative control received 100 µL cashew nut oil (CNO) and positive control received 600 mg/Kg of N-acetylcisteine (N). Mice were randomly distributed in six groups (n=8 in each group): C (Ctrl+CNO), D (DEP+CNO), DA50 (DEP+A50), DA150 (DEP+A150), DA250 (DEP+A250), DN (DEP+N). We evaluated IL-1β, TNF-α, IL-6 and IL-10 cytokines (pg/mL) in bronchoalveolar lavage fluid and lungs were removed for histological analysis. We determined the number of neutrophils in the alveolar parenchyma (cells/mm^2).
Results: D group showed significantly increased TNF-α compared to C group (118.8±54.2 and 19.8±10.8, p<0.001). There was decreased of TNF-α levels in DA50 and DN (25.8±6.4 and 65.8±29.1, p<0.05) when compared with D group. IL-6 and IL-10 did not show any statistically significant difference, but IL-1β showed increased levels in DA150 and DA250 (451.4±138.1 and 459.7±175.8) compared with D (228.52±66.25), p<0.05. D group compared with C showed increased influx of neutrophils (359.5±46.9 and 131.2±33.6, p<0.001). There was a decreased neutrophils in DA50 and DA150 related to D group (155.07±71.38 and 121.13±54.36, p<0.001).
Conclusion: Our data suggest that animals that received 50 mg/kg dose of anacardic acids were less susceptible to lung inflammation in this model. Treatment with anacardic acids may protect the lung against diesel exhaust induced lung inflammation.
