Resveratrol alleviates DSS-induced IBD in mice by regulating the intestinal microbiota-macrophage-arginine metabolism axis

Xu et al. European Journal of Medical Research (2023) 28:319 https://doi.org/10.1186/s40001-023-01257-6 European Journal of Medical Research Open Access RESEARCH Resveratrol alleviates DSS‑induced IBD in mice by regulating the intestinal microbiota‑macrophage‑arginine metabolism axis Xinwei Xu1†, Dickson Kofi Wiredu Ocansey1,2†, Bing Pei3†, Yaqin Zhang1, Naijian Wang1, Zengxu Wang4* and Fei Mao1* Abstract Background Inflammatory bowel disease (IBD) is a global disease with a growing public health concern and is associated with a complex interplay of factors, including the microbiota and immune system. Resveratrol, a natural antiinflammatory and antioxidant agent, is known to relieve IBD but the mechanism involved is largely unexplored. Methods This study examines the modulatory effect of resveratrol on intestinal immunity, microbiota, metabolites, and related functions and pathways in the BALB/c mice model of IBD. Mouse RAW264.7 macrophage cell line was used to further explore the involvement of the macrophage-arginine metabolism axis. The treatment outcome was assessed through qRT-PCR, western blot, immunofluorescence, immunohistochemistry, and fecal 16S rDNA sequencing and UHPLC/Q-TOF–MS. Results Results showed that resveratrol treatment significantly reduced disease activity index (DAI), retained mice weight, repaired colon and spleen tissues, upregulated IL-10 and the tight junction proteins Occludin and Claudin 1, and decreased pro-inflammatory cytokines IL-1β, IL-6, and TNF-α. Resveratrol reduced the number of dysregulated metabolites and improved the gut microbial community structure and diversity, including reversing changes in the phyla Bacteroidetes, Proteobacteria, and Firmicutes, increasing ‘beneficial’ genera, and decreasing potential pathogens such as Lachnoclostridium, Acinobacter, and Serratia. Arginine–proline metabolism was significantly different between the colitis-treated and untreated groups. In the colon mucosa and RAW264.7 macrophage, resveratrol regulated arginine metabolism towards colon protection by increasing Arg1 and Slc6a8 and decreasing iNOS. Conclusion This uncovers a previously unknown mechanism of resveratrol treatment in IBD and provides the microbiota-macrophage-arginine metabolism axis as a potential therapeutic target for intestinal inflammation. Keywords Inflammatory bowel disease, Resveratrol, Microbiota, Arginine metabolism, Macrophage † Xinwei Xu, Dickson Kofi Wiredu Ocansey and Bing Pei contributed equally to this work. *Correspondence: Zengxu Wang Fei Mao Full list of author information is available at the end of the article © The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Xu et al. European Journal of Medical Research (2023) 28:319 Background Inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn’s disease (CD), is a global disease with growing public health concerns due to increasing incidence. In 2020, it was asserted that developing countries are in the emergence stage of IBD evolution, newly industrialized countries are in the Acceleration in Incidence stage, while Western countries are in the Compounding Prevalence stage [1]. Although the exact cause of IBD is unknown, it is believed to be associated with a complex interplay of microbiota, immune system, environmental, and genetic factors [2, 3]. IBD is linked with compositional and metabolic alterations in the intestinal microbiota (dysbiosis) coupled with immune dysregulation, where chronic inflammation shapes the gut microbiota and vice versa, contributing to the development and progression of IBD [4]. Therefore, the restoration of microbial composition and diversity, and their derived metabolites in the gut is a promising therapeutic approach in IBD. Macrophages are the gatekeepers of intestinal immune homeostasis as they discriminate between innocuous antigens and potential pathogens to maintain tolerogenic immunity, thus, their impairment leads to chronic relapsing immune dysregulation and pathologies of the gastrointestinal tract, including IBD [5]. Large numbers of macrophages are found in the colon mucosa of IBD patients and animal models, participating in the initiation and resolution of inflammation. Macrophages are polarized into either pro-inflammatory M1 phenotypes via induction by interferon γ (IFN-γ), tumor necrosis factor-alpha (TNF-α), and bacterial lipopolysaccharide (LPS) to produce a wide range of proinflammatory cytokines such as interleukin (IL)-1β and IL-6, or antiinflammatory M2 phonotypes via induction by IL-4 and IL-13 to express arginase 1 (Arg1) and anti-inflammatory cytokines, including IL-10 [6, 7]. In effect, M2 macrophages promote intestinal tissue repair and inflammation resolution and are found to also interact with the microbiota [8, 9]. The anti-inflammatory effect of macrophages is linked with arginine metabolism, as the two arginine catalytic enzymes, inducible nitric oxide synthase (iNOS) and Arg1, are well-characterized hallmark molecules of the classically and alternatively activated macrophages, respectively [10, 11]. In a related process, the depletion of intracellular creatine by downregulating the creatine transporter Slc6a8 (solute carrier family 6 member 8) alters macrophage-mediated immune responses since creatine inhibits iNOS by suppressing IFN-γ-JAK-STAT1 signaling and promotes IL-4-STAT6activated Arg1 expression [11]. Because macrophages also express Arg1 and Slc6a8, a therapeutic substance Page 2 of 18 that modulates arginine metabolism towards increases in Arg1 and Slc6a8, would be promising in the treatment of IBD. As a potential therapy for IBD, resveratrol, a type of natural phenol and phytoalexin that acts against pathogens and possesses anti-inflammatory and antioxidant activity, has been widely studied [12, 13]. Resveratrol has been reported to relieve IBD in animal models by regulating immune responses and signaling pathways [14, 15] as well as the (...truncated)