Indole-3-carbinol ameliorates necroptosis and inflammation of intestinal epithelial cells in mice with ulcerative colitis by activating aryl hydrocarbon receptor

Synergic Role of Dietary Bioactive Compounds in Breast Cancer Chemoprevention and Combination Therapies

Breast cancer is the most common tumor in women. Chemotherapy is the gold standard for cancer treatment; however, severe side effects and tumor resistance are the major obstacles to chemotherapy success. Numerous dietary components and phytochemicals have been found to inhibit the molecular and signaling pathways associated with different stages of breast cancer development. In particular, this review is focused on the antitumor effects of PUFAs, dietary enzymes, and glucosinolates against breast cancer. The major databases were consulted to search in vitro and preclinical studies; only those with solid scientific evidence and reporting protective effects on breast cancer treatment were included. A consistent number of studies highlighted that dietary components and phytochemicals can have remarkable therapeutic effects as single agents or in combination with other anticancer agents, administered at different concentrations and via different routes of administration. These provide a natural strategy for chemoprevention, reduce the risk of breast cancer recurrence, impair cell proliferation and viability, and induce apoptosis. Some of these bioactive compounds of dietary origin, however, show poor solubility and low bioavailability; hence, encapsulation in nanoformulations are promising tools able to increase clinical efficiency.

Targeting programmed cell death in inflammatory bowel disease through natural products: New insights from molecular mechanisms to targeted therapies

Inflammatory bowel disease (IBD) is an autoimmune disorder primarily characterized by intestinal inflammation and recurrent ulceration, leading to a compromised intestinal barrier and inflammatory infiltration. This disorder's pathogenesis is mainly attributed to extensive damage or death of intestinal epithelial cells, along with abnormal activation or impaired death regulation of immune cells and the release of various inflammatory factors, which contribute to the inflammatory environment in the intestines. Thus, maintaining intestinal homeostasis hinges on balancing the survival and functionality of various cell types. Programmed cell death (PCD) pathways, including apoptosis, pyroptosis, autophagy, ferroptosis, necroptosis, and neutrophil extracellular traps, are integral in the pathogenesis of IBD by mediating the death of intestinal epithelial and immune cells. Natural products derived from plants, fruits, and vegetables have shown potential in regulating PCD, offering preventive and therapeutic avenues for IBD. This article reviews the role of natural products in IBD treatment by focusing on targeting PCD pathways, opening new avenues for clinical IBD management.

The gut microbiota-aromatic hydrocarbon receptor (AhR) axis mediates the anticolitic effect of polyphenol-rich extracts from Sanghuangporus

Inflammatory bowel disease (IBD) is a significant global health concern. The gut microbiota plays an essential role in the onset and development of IBD. Sanghuangporus (SH), a traditional Chinese medicinal mushroom, has excellent anti-inflammatory effects and is effective at modulating the gut microbiota. Despite these attributes, the specific anticolitic effects of SH and the mechanisms through which the gut microbiota mediates its benefits remain unclear. Herein, we demonstrated that polyphenol-rich extract from SH effectively alleviated the pathological symptoms of dextran sodium sulfate (DSS)-induced colitis in mice by modulating the gut microbiota. Treatment with SH distinctly enriched Alistipes, especially Alistipes onderdonkii, and its metabolite 5-hydroxyindole-3-acetic acid (5HIAA). Oral gavage of live A. onderdonkii or 5HIAA potently mitigated DSS-induced colitis in mice. Moreover, both 5HIAA and SH significantly activated the aromatic hydrocarbon receptor (AhR), and the administration of an AhR antagonist abrogated their protective effects against colitis. These results underscore the potent efficacy of SH in diminishing DSS-induced colitis through the promotion of A. onderdonkii and 5HIAA, ultimately activating AhR signaling. This study unveils potential avenues for developing therapeutic strategies for colitis based on the interplay between SH and the gut microbiota.

Formation of DNA Adducts by 1-Methoxy-3-indolylmethylalcohol, a Breakdown Product of a Glucosinolate, in the Mouse: Impact of the SULT1A1 Status-Wild-Type, Knockout or Humanised

We previously found that feeding rats with broccoli or cauliflower leads to the formation of characteristic DNA adducts in the liver, intestine and various other tissues. We identified the critical substances in the plants as 1-methoxy-3-indolylmethyl (1-MIM) glucosinolate and its degradation product 1-MIM-OH. DNA adduct formation and the mutagenicity of 1-MIM-OH in cell models were drastically enhanced when human sulfotransferase (SULT) 1A1 was expressed. The aim of this study was to clarify the role of SULT1A1 in DNA adduct formation by 1-MIM-OH in mouse tissues in vivo. Furthermore, we compared the endogenous mouse Sult1a1 and transgenic human SULT1A1 in the activation of 1-MIM-OH using genetically modified mouse strains. We orally treated male wild-type (wt) and Sult1a1-knockout (ko) mice, as well as corresponding lines carrying the human SULT1A1-SULT1A2 gene cluster (tg and ko-tg), with 1-MIM-OH. N2-(1-MIM)-dG and N6-(1-MIM)-dA adducts in DNA were analysed using isotope-dilution UPLC-MS/MS. In the liver, caecum and colon adducts were abundant in mice expressing mouse and/or human SULT1A1, but were drastically reduced in ko mice (1.2-10.6% of wt). In the kidney and small intestine, adduct levels were high in mice carrying human SULT1A1-SULT1A2 genes, but low in wt and ko mice (1.8-6.3% of tg-ko). In bone marrow, adduct levels were very low, independently of the SULT1A1 status. In the stomach, they were high in all four lines. Thus, adduct formation was primarily controlled by SULT1A1 in five out of seven tissues studied, with a strong impact of differences in the tissue distribution of mouse and human SULT1A1. The behaviour of 1-MIM-OH in these models (levels and tissue distribution of DNA adducts; impact of SULTs) was similar to that of methyleugenol, classified as "probably carcinogenic to humans". Thus, there is a need to test 1-MIM-OH for carcinogenicity in animal models and to study its adduct formation in humans consuming brassicaceous foodstuff.

Aryl Hydrocarbon Receptor Regulates Muc2 Production Independently of IL-22 during Colitis

We previously reported that an aryl hydrocarbon receptor (AhR) ligand, indole-3-carbinol (I3C), was effective at reducing colitis severity through immune cell-mediated interleukin-22 (IL-22) production. Intestinal epithelial cells (IECs) are also involved in regulating colitis, so we investigated their AhR-mediated mechanisms in the current report. A transcriptome analysis of IECs in wildtype (WT) mice revealed that during colitis, I3C regulated select mucin proteins, which could be attributed to goblet cell development. To address this, experiments under in vivo colitis (mice) or in vitro colon organoid conditions were undertaken to determine how select mucin proteins were altered in the absence or presence of AhR in IECs during I3C treatment. Comparing WT to IEC-specific AhR knockout mice (AhRΔIEC), the results showed that AhR expression was essential in IECs for I3C-mediated protection during colitis. AhR-deficiency also impaired mucin protein expression, particularly mucin 2 (Muc2), independently of IL-22. Collectively, this report highlights the important role of AhR in direct regulation of Muc2. These results provide justification for future studies aimed at determining how AhR might regulate select mucins through mechanisms such as direct transcription binding to enhance production.

RIPK1 inhibitors: A key to unlocking the potential of necroptosis in drug development

Within the field of medical science, there is a great deal of interest in investigating cell death pathways in the hopes of discovering new drugs. Over the past two decades, pharmacological research has focused on necroptosis, a cell death process that has just been discovered. Receptor-interacting protein kinase 1 (RIPK1), an essential regulator in the cell death receptor signalling pathway, has been shown to be involved in the regulation of important events, including necrosis, inflammation, and apoptosis. Therefore, researching necroptosis inhibitors offers novel ways to treat a variety of disorders that are not well-treated by the therapeutic medications now on the market. The research and medicinal potential of RIPK1 inhibitors, a promising class of drugs, are thoroughly examined in this study. The journey from the discovery of Necrostatin-1 (Nec-1) to the recent advancements in RIPK1 inhibitors is marked by significant progress, highlighting the integration of traditional medicinal chemistry approaches with modern technologies like high-throughput screening and DNA-encoded library technology. This review presents a thorough exploration of the development and therapeutic potential of RIPK1 inhibitors, a promising class of compounds. Simultaneously, this review highlights the complex roles of RIPK1 in various pathological conditions and discusses potential inhibitors discovered through diverse pathways, emphasizing their efficacy against multiple disease models, providing significant guidance for the expansion of knowledge about RIPK1 and its inhibitors to develop more selective, potent, and safe therapeutic agents.

Indirubin mediates adverse intestinal reactions in guinea pigs by downregulating the expression of AchE through AhR

Indirubin is the main component of the traditional Chinese medicine Indigo naturalis (IN), a potent agonist of aryl hydrocarbon receptors (AhRs). In China, IN is used to treat psoriasis and ulcerative colitis, and indirubin is used for the treatment of chronic myelogenous leukaemia. However, IN and indirubin have adverse reactions, such as abdominal pain, diarrhoea, and intussusception, and their specific mechanism is unclear.The purpose of our research was to determine the specific mechanism underlying the adverse effects of IN and indirubin. By tracking the modifications in guinea pigs after the intragastric administration of indirubin for 28 days.The results demonstrate that indirubin could accelerate bowel movements and decrease intestinal acetylcholinesterase (AchE) expression. Experiments with NCM460 cells revealed that indirubin significantly reduced the expression of AchE, and the AchE levels were increased after the silencing of AhR and re-exposure to indirubin.This study showed that the inhibition of AchE expression by indirubin plays a key role in the occurrence of adverse reactions to indirubin and that the underlying mechanism is related to AhR-mediated AchE downregulation.

Discovery of indole analogues from Periplaneta americana extract and their activities on cell proliferation and recovery of ulcerative colitis in mice

Background: As an important medicinal insect, Periplaneta americana (PA) has been applied for the treatment of wounds, burns, and ulcers with fewer side effects and a reduced recurrence rate, which provides great potential for developing new drugs based on its active constituents. Materials and methods: The main chromatographic peaks determined by high performance liquid chromatography (HPLC) in the PA concentrated ethanol-extract liquid (PACEL) were separated, purified, and identified by semi-preparative LC, mass spectrum, and 1H NMR spectroscopic analysis. The biological activities of the identified compounds were investigated by methylthiazolyldiphenyl-tetrazolium bromide (MTT) method based on in vitro human skin fibroblasts (HSF) and in vivo experiments based on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mouse model. Furthermore, RT-qPCR of six genes related to inflammation or intestinal epithelial cell proliferation was employed to investigate the molecular mechanism of the indole analogues recovering UC in mice. Results: Five indole analogues were purified and identified from PACEL, including tryptophan (Trp), tryptamine (pa01), 1,2,3,4-tetrahydrogen-β-carboline-3-carboxylic acid (pa02), (1S, 3S)-1-methyl-1,2,3,4-tetrahydrogen-β-carboline-3-carboxylic acid (pa03), and (1R, 3S)-1-methyl-1,2,3,4-tetrahydrogen-β-carboline-3-carboxylic acid (pa04), among which the pa02 and pa04 were reported in PA for the first time. In vitro and in vivo experiments showed that PACEL, Trp, and pa02 had promoting HSF proliferation activity and intragastric administration of them could alleviate symptoms of weight loss and colon length shortening in the UC mice. Although recovery activity of the compound pa01 on the colon length was not as obvious as other compounds, it showed anti-inflammatory activity in histological analysis. In addition, The RT-qPCR results indicated that the three indole analogues could alleviate DSS-induced intestinal inflammation in mice by inhibiting pro-inflammatory cytokines (MMP7, IL1α) and down-regulating BMP8B expression. Conclusion: This study reported the isolation, purification, structure identification, and biological activity of the active indole analogues in PACEL. It was found for the first time that the PA extract contained many indole analogues and Trp, which exhibited good proliferation activity on HSF fibroblasts as well as anti-UC activity in mice. These indole analogues probably are important components related to the pharmacological activity in PA.

Precision modulation of dysbiotic adult microbiomes with a human-milk-derived synbiotic reshapes gut microbial composition and metabolites

Manipulation of the gut microbiome using live biotherapeutic products shows promise for clinical applications but remains challenging to achieve. Here, we induced dysbiosis in 56 healthy volunteers using antibiotics to test a synbiotic comprising the infant gut microbe, Bifidobacterium longum subspecies infantis (B. infantis), and human milk oligosaccharides (HMOs). B. infantis engrafted in 76% of subjects in an HMO-dependent manner, reaching a relative abundance of up to 81%. Changes in microbiome composition and gut metabolites reflect altered recovery of engrafted subjects compared with controls. Engraftment associates with increases in lactate-consuming Veillonella, faster acetate recovery, and changes in indolelactate and p-cresol sulfate, metabolites that impact host inflammatory status. Furthermore, Veillonella co-cultured in vitro and in vivo with B. infantis and HMO converts lactate produced by B. infantis to propionate, an important mediator of host physiology. These results suggest that the synbiotic reproducibly and predictably modulates recovery of a dysbiotic microbiome.

Protective effects of salvianolic acid B on intestinal ischemia/reperfusion injury in rats by regulating the AhR/IL-22/STAT6 axis

PURPOSE

Intestinal ischemia/reperfusion (I/R) injury (IIRI) is associated with high morbidity and mortality. Salvianolic acid B (Sal-B) could exert neuroprotective effects on reperfusion injury after cerebral vascular occlusion, but its effect on IIRI remains unclear. This study set out to investigate the protective effects of Sal-B on IIRI in rats.

METHODS

The rat IIRI model was established by occluding the superior mesenteric artery and reperfusion, and they were pretreated with Sal-B and aryl hydrocarbon receptor (AhR) antagonist CH-223191 before surgery. Pathological changes in rat ileum, IIRI degree, and intestinal cell apoptosis were evaluated through hematoxylin-eosin staining, Chiu's score scale, and TUNEL staining, together with the determination of caspase-3, AhR protein level in the nucleus, and STAT6 phosphorylation by Western blotting. The levels of inflammatory cytokines (IL-1β/IL-6/TNF-α) and IL-22 were determined by ELISA and RT-qPCR. The contents of superoxide dismutase (SOD), glutathione (GSH), and malondialdehyde (MDA) in intestinal tissues were determined by spectrophotometry.

RESULTS

Sal-B alleviated IIRI in rats, evidenced by slight villi shedding and villi edema, reduced Chiu's score, and diminished the number of TUNEL-positive cells and caspase-3 expression. SAL-B alleviated inflammation and oxidative stress (OS) responses induced by IIRI. Sal-B promoted IL-22 secretion by activating AhR in intestinal tissue after IIRI. Inhibition of AhR activation partially reversed the protective effect of Sal-B on IIRI. Sal-B promoted STAT6 phosphorylation by activating the AhR/IL-22 axis.

CONCLUSION

Sal-B plays a protective role against IIRI in rats by activating the AhR/IL-22/STAT6 axis, which may be achieved by reducing the intestinal inflammatory response and OS responses.

Modulating AHR function offers exciting therapeutic potential in gut immunity and inflammation

Aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a classical exogenous synthetic ligand of AHR that has significant immunotoxic effects. Activation of AHR has beneficial effects on intestinal immune responses, but inactivation or overactivation of AHR can lead to intestinal immune dysregulation and even intestinal diseases. Sustained potent activation of AHR by TCDD results in impairment of the intestinal epithelial barrier. However, currently, AHR research has been more focused on elucidating physiologic AHR function than on dioxin toxicity. The appropriate level of AHR activation plays a role in maintaining gut health and protecting against intestinal inflammation. Therefore, AHR offers a crucial target to modulate intestinal immunity and inflammation. Herein, we summarize our current understanding of the relationship between AHR and intestinal immunity, the ways in which AHR affects intestinal immunity and inflammation, the effects of AHR activity on intestinal immunity and inflammation, and the effect of dietary habits on intestinal health through AHR. Finally, we discuss the therapeutic role of AHR in maintaining gut homeostasis and relieving inflammation.

Indole-3-Carbinol: Occurrence, Health-Beneficial Properties, and Cellular/Molecular Mechanisms

Indole-3-carbinol (I3C) is a bioactive phytochemical abundant in cruciferous vegetables. One of its main in vivo metabolites is 3,3'-diindolylmethane (DIM), formed by the condensation of two molecules of I3C. Both I3C and DIM alter multiple signaling pathways and related molecules controlling diverse cellular events, including oxidation, inflammation, proliferation, differentiation, apoptosis, angiogenesis, and immunity. There is a growing body of evidence from both in vitro and in vivo models that these compounds possess strong potential to prevent several forms of chronic disease such as inflammation, obesity, diabetes, cardiovascular disease, cancer, hypertension, neurodegenerative diseases, and osteoporosis. This article reviews current knowledge of the occurrence of I3C in nature and foods, along with the beneficial effects of I3C and DIM concerning prevention and treatment of human chronic diseases, focusing on preclinical studies and their mechanisms of action at cellular and molecular levels.

A microbiota and dietary metabolite integrates DNA repair and cell death to regulate embryo viability and aneuploidy during aging

During aging, environmental stressors and mutations along with reduced DNA repair cause germ cell aneuploidy and genome instability, which limits fertility and embryo development. Benevolent commensal microbiota and dietary plants secrete indoles, which improve healthspan and reproductive success, suggesting regulation of germ cell quality. We show that indoles prevent aneuploidy and promote DNA repair and embryo viability, which depends on age and genotoxic stress levels and affects embryo quality across generations. In young animals or with low doses of radiation, indoles promote DNA repair and embryo viability; however, in older animals or with high doses of radiation, indoles promote death of the embryo. These studies reveal a previously unknown quality control mechanism by which indole integrates DNA repair and cell death responses to preclude germ cell aneuploidy and ensure transgenerational genome integrity. Such regulation affects healthy aging, reproductive senescence, cancer, and the evolution of genetic diversity in invertebrates and vertebrates.

Curative effects of fucoidan on acetic acid induced ulcerative colitis in rats via modulating aryl hydrocarbon receptor and phosphodiesterase-4

Background

Ulcerative colitis (UC) is an inflammatory bowel disease. Fucoidan, sulfated polysaccharide of brown seaweed, demonstrates various pharmacological actions as anti-inflammatory, anti-tumor and anti-bacterial effects. Therefore, we opt to investigate the potential curative effects of fucoidan in experimentally induced UC in rats through modulating aryl hydrocarbon receptor (AhR), phosphodiesterase-4 (PDE4), nuclear factor erythroid 2-related factor 2 (Nrf2) and Heme Oxygenase-1 (HO-1).

Methods

UC was induced in rats using intracolonic 2 ml of 4% acetic acid. Some rats were treated with 150 mg/kg fucoidan. Samples of colon were used to investigate gene and protein expression of AhR, PDE4, Nrf2, HO-1 and cyclic adenosine monophosphate (cAMP). Sections of colon were stained with hematoxylin/eosin, Alcian blue or immune-stained with anti-PDE4 antibodies.

Results

Investigation of hematoxylin/eosin stained micro-images of UC rats revealed damaged intestinal glands, severe hemorrhage and inflammatory cell infiltration, while sections stained with Alcian Blue revealed damaged and almost absent intestinal glands. UC results in elevated gene and protein expression of PDE4 associated with reduced gene and protein expression of AhR, IL-22, cAMP, Nrf2 and HO-1. Finally, UC increased the oxidative stress and reduced antioxidant activity in colon tissues. All morphological changes as well as gene and protein expressions were ameliorated by fucoidan.

Conclusion

Fucoidan could treat UC induced in rats. It restored the normal weight and length of colon associated with morphological improvement as found by examining sections stained with hematoxylin/eosin and Alcian Blue. The curative effects could be explained by enhancing antioxidant activity, reducing the expression of PDE4 and increasing the expression of AhR, IL-22 and cAMP.

Role of AHR Ligands in Skin Homeostasis and Cutaneous Inflammation

Aryl hydrocarbon receptor (AHR) is an important regulator of skin barrier function. It also controls immune-mediated skin responses. The AHR modulates various physiological functions by acting as a sensor that mediates environment–cell interactions, particularly during immune and inflammatory responses. Diverse experimental systems have been used to assess the AHR’s role in skin inflammation, including in vitro assays of keratinocyte stimulation and murine models of psoriasis and atopic dermatitis. Similar approaches have addressed the role of AHR ligands, e.g., TCDD, FICZ, and microbiota-derived metabolites, in skin homeostasis and pathology. Tapinarof is a novel AHR-modulating agent that inhibits skin inflammation and enhances skin barrier function. The topical application of tapinarof is being evaluated in clinical trials to treat psoriasis and atopic dermatitis. In the present review, we summarize the effects of natural and synthetic AHR ligands in keratinocytes and inflammatory cells, and their relevance in normal skin homeostasis and cutaneous inflammatory diseases.