Beneficial role of Pistacia lentiscus aqueous extract in experimental colitis: anti-inflammatory and potential therapeutic effects

Background: Pistacia lentiscus L. (PL) is a flowering plant traditionally used in the treatment of gastrointestinal disorders. The extracts of this plant are endowed with strong pharmacological activities. The aim of our current study was to investigate the anti-inflammatory and potential therapeutic effects of PL leaves aqueous extract (PLAE) against Dextran Sulfate Sodium (DSS)-induced acute colitis. Materials and methods: The therapeutic effect of PLAE was evaluated after orally administration of 3% DSS alone or concomitantly with PLAE (50, 100 or 200 mg/Kg). Mucosal lesions were assessed by macroscopic and histopathological examination. In this context, hemorrhage, diarrhea, weight loss, and disease activity index (DAI) were determined daily throughout the experiment. In the same way, hematoxylin–eosin and Alcian blue staining of colonic mucosal were used to evaluate, respectively, mucosal damages and mucus production. Furthermore, the levels of nitric oxide (NO), and pro-inflammatory cytokines [tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)] were measured in plasma, as well as in colonic explants and peritoneal macrophages cultures supernatants. Results: Administration of DSS + PLAE indicated a significant reduction in clinical score of acute colitis DAI compared to DSS alone administration. Interestingly, histological analysis of the mucosa showed that DSS + PLAE-treated groups exhibited almost normal histology evidenced by an intact epithelium structure and less inflammatory cell infiltration in the mucosa. Alcian bleu staining revealed that DSS + PLAE-treated groups displayed almost normal mucus production. Importantly, a significant decrease in pro-inflammatory mediators (NO, IL-6 and TNF-α) levels in dose-dependent manner was reported in plasma, and culture supernatants of colonic explants and peritoneal macrophages from DSS + PLAE-treated mice compared to the DSS group. Conclusion: Our results showed that the systemic and local anti-inflammatory activities of aqueous leaves extract of PL improve the clinical signs of acute colitis. Our data suggest that PLAE has beneficial effects and could constitute a promising approach against acute ulcerative colitis by targeting the deregulated immune response.