Bioaccessible Sulforaphane Drives Macrophage Migration and Differentiation by Reprogramming the Interleukin Profile in Intestinal Inflammation

Abstract

Inflammatory bowel disease (IBD) arises from dysregulated interactions between the immune system and the intestinal microenvironment. Finding new therapeutic targets could help to develop treatments that attenuate its severity. The present study investigated the immunomodulatory potential of bioaccessible sulforaphane (SFN, 0.100 μg/mL) from broccoli by-products. Interestingly, the main results evidenced that at this physiological concentration, SFN contributed to reducing the secretion of pro-inflammatory interleukins (IL-1β, IL-6, IL-17, IL-18, IL-23, TNF-α) by intestinal epithelium up to ~56%, whereas enhancing anti-inflammatory cytokines (IL-10, IL-4, IL-13) between ~24% and ~71%. These changes adjusted the proportion of CD86⁺ and CD206⁺ during macrophage differentiation, associated with the prevention of immune-mediated IBD. In addition, a reduction in the expression of macrophage-dependent pro-inflammatory cytokines and an augmentation of the tolerogenic classes were observed. The combined use of intestinal epithelial (Caco-2) and monocytic (THP-1) cell lines established an in vitro model of the epithelium-macrophage crosstalk, thereby enhancing the physiological relevance of our findings. These results were confirmed using a pure SFN-based model system, which demonstrated SFN's contribution to the anti-inflammatory properties of broccoli stalk and bridged the gap between in vitro findings and potential dietary/therapeutic applications. Thereby, this work demonstrated that dietary SFN contributes to a large extent to the reshaping capacity of the phytochemical burden of broccoli stalks, on the interleukin profile secreted by epithelium and macrophages, as well as the macrophage differentiation, thus supporting the valorisation of broccoli by-products for preventing and managing inflammatory conditions, such as IBD.

Keywords: bioaccessibility; broccoli by‐products; interleukin modulation; intestinal inflammation; macrophage polarization; sulforaphane.