Protective effect of angiotensin II receptor blocker against oxidative stress and inflammation in an oral mucositis experimental model

Background The aim of this study was to evaluate the effect of olmesartan medoxomil (Olme), an angiotensin II receptor antagonist, on oral mucositis ( OM ) experimental model. Methods Oral mucositis was induced in hamsters with 5‐fluorouracil (5‐ FU ; 60 mg/kg day 1 and 40 mg/kg day 2). Animals (n = 10/group) were pretreated with oral Olme (1, 5, or 10 mg/kg) or vehicle 30 minutes before 5‐ FU injection and daily, until day 10. Cheek pouch samples were subjected to histopathological and immunostaining analysis of IL ‐1β, TNF ‐α, IL ‐10, TGF ‐β, macrophage migration inhibitory factor ( MIF ), SOD , MMP ‐2 and FGF ‐2. In addition, IL ‐1β and TNF ‐α levels were evaluated by ELISA . Myeloperoxidase activity ( MPO ), glutathione ( GSH ) and malondialdehyde ( MDA ) levels were investigated by spectroscopic UV / VIS analysis. Reverse transcriptase polymerase chain reactions ( RT ‐ PCR s) were used to quantify the expression of IL ‐1 β , TNF ‐ α , NF ‐ κ Bp65 , MKP 1 and ACE 2 . Inducible nitric oxide synthase ( iNOS ) and extracellular regulated kinase ( ERK )1/2 protein levels were analysed by Western blot. Results Treatment with 10 mg/kg Olme reduced ulceration, inflammatory cell infiltration, MPO activity, MDA levels, iNOS and ERK 1/2 proteins levels, MIF expression and TNF ‐α and IL ‐1β of levels and gene expression. These findings were associated with a significant increase in the immunostaining of IL ‐10, FGF ‐2 and TGF ‐β. In addition, gene expression of IL ‐1 β , TNF‐ α , NF ‐ κBp65 MKP1 and ACE2 was decreased. Conclusion Olmesartan at a dose of 10 mg/kg prevented the mucosal damage and inflammation associated with 5‐ FU ‐induced OM , increasing granulation and tissue repair.