Protective effects of Sulphorhane against injury of endocrine pancreas in diabetic mice include antiferroptotic action

Abstract

Sulforaphane (SFN) is a natural sulphur-containing compound with various beneficial biological effects that is found in cruciferous vegetables. Among others, these effects include the activation of Nrf2, a transcription factor that plays an important role in the prevention of ferroptosis, a cell death characterized by the accumulation of labile iron, glutathione (GSH) depletion and lipid peroxidation. Recently, we have demonstrated the antiferroptotic hepatoprotective effect of SFN in diabetic mice. Since ferroptosis has also been confirmed by us and others as one of the causes of β-cell destruction in diabetes, we aimed to investigate the potential of SFN treatment in preventing/eliminating injury of pancreatic islets during diabetes development in vivo. For this purpose, male C57BL/6 mice were divided into four groups (n=8): Control (Crtl), SFN-treated (SFN, 2.5 mg/kg), diabetic (DM, treated with 40 mg/kg streptozotocin from day 1-5) and diabetic SFN-treated (DM+SFN) group. All animals received an intraperitoneal injection of SFN or vehicle for 42 days and were sacrificed on day 43. Pancreata were isolated and prepared for histologic analysis and determination of GSH content. Glycemia was measured once a week during the experiment. Consistent with the improved glycemia, we observed histologic evidence of improvement in the endocrine pancreas of the DM+SFN animals: pancreatic GSH content was restored, average islet size and insulin immunopositivity returned to control values, and there was less insulitis than in the DM group. Lipid peroxidation, which was greatly increased in the DM islets as shown by 4-HNE immunopositivity, also decreased in the DM+SFN animals, while Nrf2 increased. As a sign of improved islet regeneration, PDX-1 immunoexpression strongly increased in this group. To investigate whether SFN as a natural H2S donor affects the endogenous production of this gasotransmitter in islet cells, immunoexpression of cystathionine-β- synthase (CBS) and cystathionine gamma-lyase (CSE) was also analyzed. The results showed that SFN increased CBS expression in islets under diabetogenic insults. In summary, we have shown that SFN prevents diabetogenic islet damage by activating antiferroptotic signaling pathways. Moreover, our results indicate the importance of the H2S/CBS signaling pathway in protecting islet cells from DM insult, indicating this pathway as a potential antidiabetic target.