Background and aims: Recent studies have shown that daily use of NSAIDs, frequently causes small intestinal ulcers and erosions. However, effective drugs to prevent aspirin/NSAIDs-induced small intestinal lesions have not been developed. In the present study, we examined the effects of sulforaphane (SFN), a substance rich in broccoli sprouts, on aspirin/NSAIDs-induced small intestinal injury.
Methods: 1. In vitro study: IEC6 cells, derived from rat small intestinal mucosae, were incubated with or without SFN. The cells were subsequently exposed to aspirin. In some experiments, the effect of zinc protoporphyrin-IX (ZnPP), 0.1 μM, an inhibitor of heme oxygenase- 1 (HO-1), was also examined. 2. In vivo study: IND-induced small intestinal mucosal injury was induced in male ddY mice. SFN glucosinolates (SGS), which is glucosinolates precursor of SFN, was orally administered to the mice, at dose of 17 mg/mouse, before and after the injection of IND. Vascular permeability was assessed by measuring the amount of exudated Evans Blue in the mucosa, which had been injected intravenously. Neutrophil activation was evaluated by myeloperoxidase (MPO) activity. Amount of mucosal anaerobic bacteria was also measured.
Results: 1. In vitro study: (1) SFN, 5 μM, significantly attenuated aspirin (20 mM)-induced cell injury. (2) SFN enhanced HO-1 expression in IEC-6 cells. The protective effect of SFN against aspirin-induced injury was attenuated by 0.1 μM ZnPP. 2. In vivo study: (1) IND treatment caused mucosal injury in small intestine, increased vascular permeability, enhanced MPO activity, and augmented mucosal invasion of anaerobic enterobacteria. (2) SGS attenuated the IND-induced small intestinal injury. (3) SGS prevented the IND-induced increase in mucosal invasion of anaerobic enterobacteria.
Conclusions: These results suggest that SFN protects small intestine from aspirin / NSAIDs-induced injury, presumably by up-regulating nrf2-keap1 dependent antioxidant system and by inhibiting invasion of anaerobic bacteria into the mucosa.