Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 17 5 2018 10 14 409 417 EN Elham Harati Iranian Center of Neurological Research, Neuroscience Institute, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran AND Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Maryam Bahrami Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Alireza Razavi Department of Pathobiology, Division of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran Mohammad Kamalinejad Department of Pharmacognosy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran Maryam Mohammadian Department of Physiology, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran Tayebeh Rastegar Department of Anatomy, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Hamid Reza Sadeghipour Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 2017 10 05 2017 12 23 Asthma is a chronic inflammatory disease of the lungs driven by T cell activation. Viola tricolor L. as a traditional medical herb could suppress activated T lymphocytes and has been used empirically for asthma remedy. In the present study, we investigated the anti-inflammatory effect of Viola tricolor and its underlying mechanism on asthma characteristics induced by ovalbumin (OVA) in mice. BALB/c mice were randomly divided into six groups: normal control, Ovalbumin (OVA) control, OVA mice treated with Viola tricolor (50, 100 and 200 mg/kg) and dexamethasone (3 mg/kg). All mice except normal controls were sensitized and challenged with OVA. Asthmatic mice were treated orally in the last 7 days of OVA challenge. The total and differential leukocyte counts, Interleukin (IL)-4 and interferon (IFN)-γ levels in bronchoalveolar lavage fluid (BALF) were determined. H and E staining for lung inflammation was performed. Viola tricolor treatment at 200 mg/kg significantly decreased IL-4 level but did not considerably affect the IFN-γ level. Therefore, it effectively reduced asthma characteristics including infiltration of leukocytes particularly eosinophil and peribronchial inflammation as compared to dexamethasone. However, Viola tricolor at 100 mg/kg had the most prominent inhibitory effect on the IL-4 level and also markedly increased IFN-γ level. As result, it prevented further reduction of inflammatory parameters in this group compared to the Viola tricolor-treated group at 200 mg/kg. Our study demonstrated that Viola tricolor has anti-inflammatory effects via inhibition of T-helper type 2 (Th2) cytokine production and validated its empirical usage in traditional medicine. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/1678 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/1678/1361