Evidence-based pathogenesis and treatment of ulcerative colitis: A causal role for colonic epithelial hydrogen peroxide

Lizhong decoction ameliorates ulcerative colitis by inhibiting ferroptosis of enterocytes via the Nrf2/SLC7A11/GPX4 pathway

ETHNOPHARMACOLOGY RELEVANCE

Traditional herbal medicines have been considered as a novel and effective way to treat many diseases. Lizhong decoction (LZD), a classical prescription composed of Zingiber officinale Rosc., Panax ginseng C. A. Mey., Atractylodes macrocephala Koidz., and Glycyrrhiza uralensis Fisch., has been used to treat gastrointestinal disorders in clinical practices for thousands of years. However, the mechanism of LZD in alleviating ulcerative colitis (UC) is still unclear.

AIM OF THE STUDY

The purpose of this study was to clarify the potential molecular mechanism of LZD in improving UC.

MATERIALS AND METHODS

The amelioration of LZD on dextran sodium sulfate (DSS)-induced UC mice was evaluated by body weight, colon length, pathology of colon tissues, pro-inflammatory cytokines, and intestinal tight junction (TJ) proteins. Moreover, the gene expression profiles of UC patients were extracted to investigate potential pathological mechanisms of UC. The influence of LZD on ferroptosis was analyzed by iron load, malondialdehyde (MDA), and the expression of ferroptosis-associated proteins. Meanwhile, the inhibition of LZD on oxidative stress (OS) was assessed by the superoxide dismutase (SOD) activity, as well as the expression levels of glutathione (GSH) and glutathione disulfide (GSSG). Furthermore, the influence of LZD on ferroptosis was assessed by inhibiting nuclear factor (erythroid-derived-2)-like 2 (Nrf2).

RESULTS

LZD showed significant therapeutic effects in UC mice, including reduction of intestinal injury and inflammation. Moreover, LZD treatment notably upregulated the expression of TJ proteins. Further investigation indicated that LZD significantly inhibited the ferroptosis of enterocytes by decreasing iron load and MDA, and increasing the expression levels of solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) in colon tissues. Furthermore, the decreased activity of SOD, reduced level of GSH, and increased content of GSSG in UC mice were notably reversed by LZD. Consistent with in vivo results, LZD could markedly inhibit ferroptosis and OS in RSL3-induced Caco-2 cells. Mechanistically, LZD alleviated ferroptosis by suppressing OS through the activation of Nrf2 signaling.

CONCLUSIONS

Collectively, LZD remarkably improved intestinal pathological injury in UC mice, and its potential mechanism was the suppression of ferroptosis in enterocytes by the Nrf2/SLC7A11/GPX4 pathway.

Transient gestational hypothyroxinemia accelerates and enhances ulcerative colitis-like disorder in the male offspring

Introduction

Gestational hypothyroxinemia (HTX) is a condition that occurs frequently at the beginning of pregnancy, and it correlates with cognitive impairment, autism, and attentional deficit in the offspring. Evidence in animal models suggests that gestational HTX can increase the susceptibility of the offspring to develop strong inflammation in immune-mediated inflammatory diseases. Ulcerative colitis (UC) is a frequent inflammatory bowel disease with unknown causes. Therefore, the intensity of ulcerative colitis-like disorder (UCLD) and the cellular and molecular factors involved in proinflammatory or anti-inflammatory responses were analyzed in the offspring gestated in HTX (HTX-offspring) and compared with the offspring gestated in euthyroidism (Control-offspring).

Methods

Gestational HTX was induced by the administration of 2-mercapto-1-methylimidazole in drinking water to pregnant mice during E10-E14. The HTX-offspring were induced with UCLD by the acute administration of dextran sodium sulfate (DSS). The score of UCLD symptomatology was registered every day, and colon histopathology, immune cells, and molecular factors involved in the inflammatory or anti-inflammatory response were analyzed on day 6 of DSS treatment.

Results

The HTX-offspring displayed earlier UCLD pathological symptoms compared with the Control-offspring. After 6 days of DSS treatment, the HTX-offspring almost doubled the score of the Control-offspring. The histopathological analyses of the colon samples showed signs of inflammation at the distal and medial colon for both the HTX-offspring and Control-offspring. However, significantly more inflammatory features were detected in the proximal colon of the HTX-offspring induced with UCLD compared with the Control-offspring induced with UCLD. Significantly reduced mRNA contents encoding for protective molecules like glutamate-cysteine ligase catalytic subunit (GCLC) and mucin-2 (MUC-2) were found in the colon of the HTX-offspring as compared with the Control-offspring. Higher percentages of Th17 lymphocytes were detected in the colon tissues of the HTX-offspring induced or not with UCLD as compared with the Control-offspring.

Discussion

Gestational HTX accelerates the onset and increases the intensity of UCLD in the offspring. The low expression of MUC-2 and GCLC together with high levels of Th17 Lymphocytes in the colon tissue suggests that the HTX-offspring has molecular and cellular features that favor inflammation and tissue damage. These results are important evidence to be aware of the impact of gestational HTX as a risk factor for UCLD development in offspring.

Iron chelation and supplementation: A comparison in the management of inflammatory bowel disease using drosophila

AIMS

Inflammatory Bowel Disease (IBD) is associated with systemic iron deficiency and has been managed with iron supplements which cause adverse side effects. Conversely, some reports highlight iron depletion to ameliorate IBD. The underlying intestinal response and comparative benefit of iron depletion and supplementation in IBD is unknown. The aims of this work were to characterize and compare the effects of iron supplementation and iron depletion in IBD.

MAIN METHODS

IBD was induced in Drosophila melanogaster using 3 % dextran sodium sulfate (DSS) in diet for 7 days. Using this model, we investigated the impacts of acute iron depletion (using bathophenanthroline disulfonate, BPS) and supplementation (using ferrous sulphate, FS), before and after IBD induction, on gut iron homeostasis, cell death, gut permeability, inflammation, antioxidant defence, antimicrobial response and several fly phenotypes.

KEY FINDINGS

DSS decreased fly mass (p < 0.001), increased gut permeability (p < 0.001) and shortened lifespan (p = 0.035) compared to control. The DSS-fed flies also showed significantly elevated lipid peroxidation (p < 0.001), and the upregulated expression of apoptotic marker- drice (p < 0.001), tight junction protein - bbg (p < 0.001), antimicrobial peptide - dpta (p = 0.002) and proinflammatory cytokine - upd2 (p < 0.001). BPS significantly (p < 0.05) increased fly mass and lifespan, decreased gut permeability, decreased lipid peroxidation and decreased levels of drice, bbg, dpta and upd2 in IBD flies. This iron chelation (using BPS) showed better protection from DSS-induced IBD than iron supplementation (using FS). Preventive and curative interventions, by BPS or FS, also differed in outcomes.

SIGNIFICANCE

This may inform precise management strategies aimed at tackling IBD and its recurrence.

Synthesis of Bis-Chalcones and Evaluation of Its Effect on Peroxide-Induced Cell Death and Lipopolysaccharide-Induced Cytokine Production

Plant secondary metabolites are important sources of biologically active compounds with wide pharmacological potentials. Among the different classes, the chalcones form integral pharmacologically active agents. Natural chalcones and bis-chalcones exhibit high antioxidant and anti-inflammatory properties in various experiments. Studies are also underway to explore more biologically active bis-chalcones by chemical synthesis of these compounds. In this study, the effects of six synthetic bis-chalcones were evaluated in intestinal epithelial cells (IEC-6); further, the anti-inflammatory potentials were studied in lipopolysaccharide-induced cytokine production in macrophages. The synthesized bis-chalcones differ from each other first of all by the nature of the aromatic cores (functional group substitution, and their position) and by the size of a central alicycle. The exposure of IEC-6 cells to peroxide radicals reduced the cell viability; however, pre-treatment with the bis-chalcones improved the cell viability in these cells. The mechanism of action was observed to be the increased levels of glutathione and antioxidant enzyme activities. Further, these bis-chalcones also inhibited the LPS-stimulation-induced inflammatory cytokine production in RAW 264.7 macrophages. Overall, the present study indicated the cytoprotective and anti-inflammatory abilities of synthetic bis-chalcones.

Toll-like Receptors and Cytokine Modulation by Goat Milk Extracellular Vesicles in a Model of Intestinal Inflammation

Extracellular vesicles (EVs) are nanometric spherical structures, enclosed in a lipid bilayer membrane and secreted by multiple cell types under specific physiologic and pathologic conditions. Their complex cargo modulates immune cells within an inflammatory microenvironment. Milk is one of the most promising sources of EVs in terms of massive recovery, and milk extracellular vesicles (mEVs) have immunomodulatory and anti-inflammatory effects. The aim of this study was to characterize goat mEVs' immunomodulating activities on Toll-like receptors (TLRs) and related immune genes, including cytokines, using a porcine intestinal epithelial cell line (IPEC-J2) after the establishment of a pro-inflammatory environment. IPEC-J2 was exposed for 2 h to pro-inflammatory stimuli as a model of inflammatory bowel disease (IBD), namely LPS for Crohn's disease (CD) and H₂O₂ for ulcerative colitis (UC); then, cells were treated with goat mEVs for 48 h. RT-qPCR and ELISA data showed that cell exposure to LPS or H₂O₂ caused a pro-inflammatory response, with increased gene expression of CXCL8, TNFA, NOS2 and the release of pro-inflammatory cytokines. In the LPS model, the treatment with mEVs after LPS determined the down-regulation of NOS2, MMP9, TLR5, TGFB1, IFNB, IL18 and IL12A gene expressions, as well as lower release of IL-18 in culture supernatants. At the same time, we observed the increased expression of TLR1, TLR2, TLR8 and EBI3. On the contrary, the treatment with mEVs after H₂O₂ exposure, the model of UC, determined the increased expression of MMP9 alongside the decrease in TGFB1, TLR8 and DEFB1, with a lower release of IL-1Ra in culture supernatants. Overall, our data showed that a 48 h treatment with mEVs after a pro-inflammatory stimulus significantly modulated the expression of several TLRs and cytokines in swine intestinal cells, in association with a decreased inflammation. These results further highlight the immunomodulatory potential of these nanosized structures and suggest their potential application in vivo.