Acute colitis induced by dextran sulfate sodium progresses to chronicity in C57BL/6 but not in BALB/c mice: correlation between symptoms and inflammation

FGF1ΔHBS ameliorates DSS-induced ulcerative colitis by reducing neutrophil recruitment through the MAPK pathway

BACKGROUND AND PURPOSE

Inflammatory bowel diseases (IBDs) constitute chronic inflammatory disease of the gastrointestinal tract, with escalating global prevalence. There is a pressing demand for safe and effective treatments for IBDs. Fibroblast growth factor 1 (FGF1) variant FGF1ΔHBS, characterised by reduced mitogenic capacity, has shown promising therapeutic potential in various inflammatory conditions, including obesity and diabetic nephropathy. Hence, exploring the therapeutic impact of FGF1ΔHBS on colitis is warranted.

EXPERIMENTAL APPROACH

The protective role of FGF1ΔHBS was evaluated using a dextran sulphate sodium (DSS)-induced colitis model in mice. RNA-seq analysis was performed on colonic tissues. Inflammatory factor expression was examined by quantitative real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay. Flow cytometry and immunofluorescence staining were employed to confirm the inhibitory effect of FGF1ΔHBS on neutrophil recruitment. Western blotting was performed to explore the mitogen-activated protein kinase (MAPK) signalling pathway.

KEY RESULTS

FGF1ΔHBS significantly alleviated DSS-induced colitis, as indicated by reduced Disease Activity Index scores and less histological injury to the colon. Additionally, FGF1ΔHBS decreased the expression of pro-inflammatory factors. Mechanistically, FGF1ΔHBS inhibited neutrophil-associated chemokine expression in intestinal epithelial cells by suppressing the MAPK signalling pathway, thereby reducing neutrophil recruitment and attenuating neutrophil-mediated intestinal inflammation.

CONCLUSION AND IMPLICATIONS

FGF1ΔHBS protects against DSS-induced colitis in mice by inhibiting neutrophil recruitment through MAPK activity suppression, suggesting a potential therapeutic strategy for preventing IBDs.

Atractylodes macrocephala Koidz polysaccharide ameliorates DSS-induced colitis in mice by regulating the gut microbiota and tryptophan metabolism

BACKGROUND AND PURPOSE

Ulcerative colitis (UC) is an idiopathic inflammatory bowel disease, and the range of current clinical treatments is not ideal. We previously found that polysaccharide of Atractylodes macrocephala Koidz (PAMK) is beneficial in DSS-induced colitis, and we aimed to investigate the underlying mechanisms in this study.

EXPERIMENTAL APPROACH

PAMK was used to treat DSS-induced colitis in mice, 16S rRNA sequencing analysis was used to detect changes in the intestinal microbiota, targeted metabolomics analysis was used to determine the content of tryptophan-metabolizing bacteria, and western blotting was used to determine aryl hydrocarbon receptor (AhR) and pregnane X receptor (PXR) levels. Furthermore, antibiotic-mediated depletion of gut microbiota and faecal microbiota transplantation were performed to assess the role of the gut microbiota in PAMK alleviation of colitis.

KEY RESULTS

PAMK treatment relieved intestinal microbiota dysbiosis in mice with colitis, contributed to the proliferation of tryptophan-metabolizing bacteria, and increased the levels of tryptophan metabolites, resulting in a significant increase in the nuclear translocation of PXR and expression of PXR and its target genes, but not AhR. The gut microbiota is important in PAMK treatment of colitis, including in the alleviation of symptoms, inhibition of inflammation, maintenance of the integrity of the intestinal barrier, and the regulation of the Th17/Treg cell balance.

CONCLUSION AND IMPLICATIONS

Based on our findings, we elucidate a novel mechanism by which PAMK alleviates DSS-induced colitis and thus provides evidence to support the potential development of PAMK as a new clinical drug against UC.

Morphofunctional changes in the immune system in colitis-associated colorectal cancer in tolerant and susceptible to hypoxia mice

Background

One of the effective strategies for the treatment of tumor diseases, including colitis-associated colorectal cancer (CAC), is immunotherapy. During inflammation, NF-κB is activated, which is connected with the hypoxia-inducible factor-HIF, regulating the immune cells functioning and influences the CAC development. Organisms differ according to their hypoxia resistance and HIF expression. Therefore, the aim of the study was to characterize the thymus, spleen and mesenteric lymph nodes morphofunctional features, as well as changes in the subpopulation composition of peripheral blood cells and mesenteric lymph nodes in tolerant and susceptible to hypoxia C57Bl/6 mice in CAC.

Methods

Hypoxia tolerance was assessed by gasping time measurement in hypobaric decompression chamber. Based on the outcome, the mice were assigned to three groups characterized as 'tolerant to hypoxia', 'normal', and 'susceptible to hypoxia'. A month after determining hypoxia resistance CAC was modeled by intraperitoneal azoxymethane (AOM) administration and three cycles of dextran sulfate sodium consumption. Mice were sacrificed on the 141st day after the AOM administration, a morphological, morphometric and immunohistochemical study of tumors, morphological and morphometric study of thymus and spleen, and subpopulation composition of peripheral blood cells and mesenteric lymph nodes assessment were carried out.

Results

Tumors in tolerant and susceptible to hypoxia mice were represented by glandular intraepithelial neoplasia and adenocarcinomas, the area of which was larger in susceptible mice. Immunohistochemical study revealed a more pronounced Ki-67+ staining in tumors of susceptible mice. In CAC, only in tolerant mice, expansion of the thymic cortex was observed relative to the control group, while in susceptible ones, no changes were detected. Only in susceptible to hypoxia mice, spleen germinal centers of lymphoid follicles enlargement were observed. Only in susceptible mice during CAC, in comparison to the control group, the relative and absolute number of B-lymphocytes and relative-cytotoxic T-lymphocytes in blood increased. The relative cytotoxic T-lymphocytes and NK cells number in peripheral blood during CAC was higher in susceptible to hypoxia mice compared to tolerant ones. In susceptible to hypoxia mice, more pronounced changes in the mesenteric lymph nodes subpopulation composition of cells were revealed-only in them the absolute and relative number of B-lymphocytes and NK cells, the absolute number of cytotoxic T-lymphocytes increased, and the relative number of macrophages decreased.

Conclusions

Morphofunctional differences in the thymus, spleen, mesenteric lymph nodes and blood immune cells reactions indicated the more pronounced immune response to the CAC development in susceptible to hypoxia mice, which should be taken into account in experimental studies.

Microencapsulation and Probiotic Characterization of Lactiplantibacillus plantarum LM-20: Therapeutic Application in a Murine Model of Ulcerative Colitis

BACKGROUND

Microencapsulation improves the storage, handling, and administration of probiotics by protecting them from environmental factors and adverse conditions in the gastrointestinal tract. This process facilitates their controlled delivery in the body, which can simplify their use in therapies without compromising their therapeutic efficacy.

OBJECTIVES

This study investigates the microencapsulation of Lactiplantibacillus plantarum LM-20, its probiotic properties, and its effects in a murine model of ulcerative colitis.

METHODS/RESULTS

Synbiotic microencapsulation was carried out using spray drying with maltodextrin, gum Arabic, and inulin, achieving an encapsulation efficiency of 90.76%. The resulting microcapsules exhibited remarkable resistance to simulated gastrointestinal conditions in vitro, maintaining a survival rate of 90%. The drying process did not compromise the probiotic characteristics of the bacteria, as they demonstrated enhanced auto-aggregation, hydrophobicity, and phenol tolerance. The therapeutic potential of the microencapsulated synbiotic was evaluated in a murine model of dextran sodium sulfate-induced ulcerative colitis. The results revealed that mice treated with microencapsulated Lactiplantibacillus plantarum LM-20 showed an 83.3% reduction in the disease activity index (DAI) compared to the ulcerative colitis control group. Moreover, a significant decrease was observed in pro-inflammatory cytokine levels (IL-1β and TNF-α) and myeloperoxidase activity, with values comparable to those of the healthy control group.

CONCLUSIONS

These findings suggest that microencapsulated Lactiplantibacillus plantarum LM-20 could be a promising candidate for therapeutic applications in the prevention and management of ulcerative colitis.

A pH-sensitive opioid does not exhibit analgesic tolerance in a mouse model of colonic inflammation

BACKGROUND AND PURPOSE

Tolerance to the analgesic effects of opioids and resultant dose escalation is associated with worsening of side effects and greater addiction risk. Here, we compare the development of tolerance to the conventional opioid fentanyl with a novel pH-sensitive μ-opioid receptor (MOR) agonist, (±)-N-(3-fluoro-1-phenethylpiperidine-4-yl)-N-phenyl propionamide (NFEPP) that is active only in acidic inflammatory microenvironments.

EXPERIMENTAL APPROACH

An opioid tolerance model was developed in male C57BL/6 mice, with and without dextran sulphate sodium colitis, using increasing doses of either fentanyl or NFEPP over 5 days. Visceral nociception was assessed in vivo by measuring visceromotor responses (VMRs) to noxious colorectal distensions and in vitro measuring colonic afferent nerve activity of mesenteric nerves and performing patch-clamp recordings from isolated dorsal root ganglia neurons. Somatic thermal nociception was tested using a tail immersion assay. Cardiorespiratory effects were analysed by pulse oximeter experiments.

KEY RESULTS

VMRs and tail immersion tests demonstrated tolerance to fentanyl, but not to NFEPP in colitis mice. Cross-tolerance also occurred to fentanyl, but not to NFEPP. The MOR agonist DAMGO inhibited colonic afferent nerve activity in colitis mice exposed to chronic NFEPP, but not those from fentanyl-treated mice. Similarly, in patch-clamp recordings from isolated dorsal root ganglia neurons, DAMGO inhibited neurons from NFEPP-, but not fentanyl-treated mice.

CONCLUSION AND IMPLICATIONS

NFEPP did not exhibit tolerance in an inflammatory pain model, unlike fentanyl. Consequently, dose escalation to maintain analgesia during an evolving inflammation could be avoided, mitigating the potential risk of side effects.

DAMP-ing IBD: Extinguish the Fire and Prevent Smoldering

In inflammatory bowel diseases (IBD), the most promising therapies targeting cytokines or immune cell trafficking demonstrate around 40% efficacy. As IBD is a multifactorial inflammation of the intestinal tract, a single-target approach is unlikely to solve this problem, necessitating an alternative strategy that addresses its variability. One approach often overlooked by the pharmaceutically driven therapeutic options is to address the impact of environmental factors. This is somewhat surprising considering that IBD is increasingly viewed as a condition heavily influenced by such factors, including diet, stress, and environmental pollution-often referred to as the "Western lifestyle". In IBD, intestinal responses result from a complex interplay among the genetic background of the patient, molecules, cells, and the local inflammatory microenvironment where danger- and microbe-associated molecular patterns (D/MAMPs) provide an adjuvant-rich environment. Through activating DAMP receptors, this array of pro-inflammatory factors can stimulate, for example, the NLRP3 inflammasome-a major amplifier of the inflammatory response in IBD, and various immune cells via non-specific bystander activation of myeloid cells (e.g., macrophages) and lymphocytes (e.g., tissue-resident memory T cells). Current single-target biological treatment approaches can dampen the immune response, but without reducing exposure to environmental factors of IBD, e.g., by changing diet (reducing ultra-processed foods), the adjuvant-rich landscape is never resolved and continues to drive intestinal mucosal dysregulation. Thus, such treatment approaches are not enough to put out the inflammatory fire. The resultant smoldering, low-grade inflammation diminishes physiological resilience of the intestinal (micro)environment, perpetuating the state of chronic disease. Therefore, our hypothesis posits that successful interventions for IBD must address the complexity of the disease by simultaneously targeting all modifiable aspects: innate immunity cytokines and microbiota, adaptive immunity cells and cytokines, and factors that relate to the (micro)environment. Thus the disease can be comprehensively treated across the nano-, meso-, and microscales, rather than with a focus on single targets. A broader perspective on IBD treatment that also includes options to adapt the DAMPing (micro)environment is warranted.

Anti-inflammatory effects of heat-killed Lactiplantibacillus argentoratensis BBLB001 on a gut inflammation co-culture cell model and dextran sulfate sodium-induced colitis mouse model

Dysbiosis caused by dietary changes can alter the intestinal bacterial species and is closely associated with inflammatory bowel disease (IBD). Among the possible treatment options, postbiotics, which act to balance the constituent intestinal microflora, have gained substantial attention. Herein, we investigated the anti-inflammatory effects of heat-killed Lactiplantibacillus argentoratensis (hk-LA) BBLB001 isolated from a marine environment using both cell (Caco2/RAW264.7 cell co-culture) and animal (dextran sodium sulfate [DSS]-induced colitis in mice) models. hk-LA BBLB001 markedly reduced IL-8 secretion in Caco-2 cell culture medium after lipopolysaccharide-mediated stimulation of RAW264.7 cells by enhancing the expression of cell adhesion factors.The body weight loss, reduced inflammatory cytokine levels in the serum and colon tissues, colon shortening, and myeloperoxidase activation caused by DSS in mice were alleviated by hk-LA BBLB001. Similar to that in the intestinal cell model, the gene and protein expressions of cell adhesion molecules in the colon tissue were increased upon hk-LA BBLB001 treatment in DSS-induced colitis mice. We observed increased mucin expression and secretory IgA concentration in colon tissues, suggesting that hk-LA BBLB001 intake may benefit pathogen defense and the regulation of intestinal commensal bacteria. Thus, hk-LA BBLB001 may serve as an instrumental postbiotic material in IBD treatment.

Exploring the efficacy of Transcutaneous Auricular Vagus nerve stimulation (taVNS) in modulating local and systemic inflammation in experimental models of colitis

BACKGROUND

Current inflammatory bowel disease (IBD) treatments often fail to achieve lasting remission and have adverse effects. Vagus nerve stimulation (VNS) offers a promising therapy due to its anti-inflammatory effects. Its invasive nature, however, has led to the development of non-invasive methods like transcutaneous auricular VNS (taVNS). This study assesses taVNS's impact on acute colitis progression, inflammatory, anti-inflammatory, and apoptosis-related markers.

METHODS

Male C57BL/6 mice (11-12 weeks) were used for dextran sulfate sodium (DSS)- and dinitrobenzene sulfonic acid (DNBS)-induced colitis studies. The administration of taVNS or no stimulation (anesthesia without stimulation) for 10 min per mouse began one day before colitis induction and continued daily until sacrifice. Ulcerative colitis (UC)-like colitis was induced by administering 5% DSS in drinking water for 5 days, after which the mice were sacrificed. Crohn's disease (CD)-like colitis was induced through a single intrarectal injection of DNBS/ethanol, with the mice sacrificed after 3 days. Disease activity index (DAI), macroscopic evaluations, and histological damage were assessed. Colon, spleen, and blood samples were analyzed via qRT-PCR and ELISA. One-way or two-way ANOVA with Bonferroni and Šídák tests were applied.

RESULTS

taVNS improved DAI, macroscopic, and histological scores in DSS colitis mice, but only partially mitigated weight loss and DAI in DNBS colitis mice. In DSS colitis, taVNS locally decreased colonic inflammation by downregulating pro-inflammatory markers (IL-1β, TNF-α, Mip1β, MMP 9, MMP 2, and Nos2) at the mRNA level and upregulating anti-inflammatory TGF-β in non-colitic conditions at both mRNA and protein levels and IL-10 mRNA levels in both non-colitic and colitic conditions. Systemically, taVNS decreased splenic TNF-α in non-colitic mice and increased serum levels of TGF-β in colitic mice and splenic levels in non-colitic and colitic mice. Effects were absent in DNBS-induced colitis. Additionally, taVNS decreased pro-apoptotic markers (Bax, Bak1, and caspase 8) in non-colitic and colitic conditions and increased the pro-survival molecule Bad in non-colitic mice.

CONCLUSIONS

This study demonstrates that taVNS has model-dependent local and systemic effects, reducing inflammation and apoptosis in UC-like colitis while offering protective benefits in non-colitic conditions. These findings encourage further research into underlying mechanisms and developing adjunct therapies for UC.

Anorectal Remodeling in the Transitional Zone with Increased Expression of LGR5, SOX9, SOX2, and Keratin 13 and 5 in a Dextran Sodium Sulfate-Induced Mouse Model of Ulcerative Colitis

Although hyperplasia of the anorectal transitional zone (TZ) has been reported in mouse models of ulcerative colitis, the mechanisms underlying this phenomenon are not fully understood. We characterized keratin subtypes and examined the expression of stem cell markers in the TZ. Dextran sodium sulfate-treated mice showed abnormal repair of the anorectal region, which consisted of mixed hyperplastic TZ and regenerating crypts. Liquid chromatography-tandem mass spectrometry from the paraffin-embedded TZ in the treated mice revealed that the major keratins were type I cytokeratin (CK)13 and type II CK5, but notable expression of type I CK10 and CK42 and type II CK1, CK4, CK6a, CK8, and CK15 was also detected. Hyperplastic TZ was characterized by the expression of tumor protein 63, sex-determining region Y-box 2 (SOX2), SOX9, and leucine-rich repeat-containing G-protein coupled receptor 5 (Lgr5). Lgr5 was highly expressed in the TZ in the early stages of colitis, followed by higher expression levels of SOX2. The TZ-derived organoids expressed LGR5, SOX2, and SOX9. The present study suggests that transitional zones showing abnormal keratin assembly and stem cell activation may interfere with rectal crypt regeneration, leading to pathological anorectal remodeling in severe colitis.

Lack of ATP2B1 in CD4+ T Cells Causes Colitis

BACKGROUND

The ATP2B1 gene encodes for a calcium pump, which plays a role in removing Ca2+ from cells and maintaining intracellular Ca2+ homeostasis. Reduction of the intracellular Ca2+ concentration in CD4+ T cells is thought to reduce the severity of colitis, while elevation of Ca2+ in CD4+ T cells induces T cell hyperactivity. Our aim was to clarify the role of ATP2B1 in CD4+ T cells and in inflammatory bowel disease development.

METHODS

A murine CD4+ T cell-specific knockout (KO) of ATP2B1 was created using a Cre-loxP system. CD4+ T cells were isolated from thymus, spleen, and blood using fluorescence-activated cell sorting. To quantify messenger RNA levels, quantitative real-time polymerase chain reaction was performed.

RESULTS

Although the percentages of CD4+ T cells in both KO mouse spleen and blood decreased compared with those of the control samples, both T-bet (a T helper 1 [Th1] activity marker) and GATA3 (a Th2 activity marker) expression levels were further increased in KO mouse blood CD4+ T cells (vs control blood). Diarrhea and colonic wall thickening (with mucosal changes, including crypt distortion) were seen in KO mice but not in control mice. Prior to diarrhea onset, the KO mouse colon length was already noted to be shorter, and the KO mouse stool water and lipid content were higher than that of the control mice. Tumor necrosis factor α and gp91 expressions were increased in KO mouse colon.

CONCLUSIONS

Lack of ATP2B1 in CD4+ T cells leads to Th1 and Th2 activation, which contributes to colitis via elevation of tumor necrosis factor α and oxidative stress.

The Role of Claudins in the Pathogenesis of Dextran Sulfate Sodium-Induced Experimental Colitis: The Effects of Nobiletin

BACKGROUND

The pathogenesis of inflammatory bowel diseases such as ulcerative colitis and Crohn's disease is not well understood. This study investigated the roles and regulation of the claudin-1, -2, -3, and -4 isoforms in the pathogenesis of ulcerative colitis, and the potential therapeutic effects of nobiletin.

METHODS

Colitis was induced in rats by administering dextran sulfate sodium [DSS] in drinking water for seven days. Animals were treated daily with nobiletin [oral, 60 mg/Kg body weight] and studied in four groups, C [non-colitis control], D [DSS-induced colitis], CN [nobiletin-treated non-colitis control], and DN [nobiletin-treated DSS-induced colitis]. On day seven, the animals were sacrificed, and colonic tissues were collected and analyzed.

RESULTS

Both macroscopic and microscopic findings suggest the progression of colitis. In the inflamed colon, claudin-1 and -4 proteins were decreased, claudin-2 increased, while the claudin-3 protein remained unchanged. Except for claudin-1, these changes were not paralleled by mRNA expression, indicating a complex regulatory mechanism. Uniform β-actin expression along with consistent quality and yield of total RNA indicated selectivity of these changes. Nobiletin treatment reversed these changes.

CONCLUSIONS

Altered expression of the claudin isoforms -1, -2, and -4 disrupts tight junctions, exposing the lamina propria to microflora, leading to electrolyte disturbance and the development of ulcerative colitis. Nobiletin with its anti-inflammatory properties may be useful in IBD.

The Immunosuppressive Properties of Cyclo-[D-Pro-Pro-β3-HoPhe-Phe-] Tetrapeptide Selected from Stereochemical Variants of Cyclo-[Pro-Pro-β3-HoPhe-Phe-] Peptide

The anti-inflammatory, antiviral, and anti-cancer properties, as well as the mechanism of action of cyclo-[Pro-Pro-β3-HoPhe-Phe-] tetrapeptide (denoted as 4B8M), were recently described. The aim of this work was to synthesize and evaluate the immunosuppressive actions of the stereochemical variants of 4B8M by sequential substitution of L-amino acids by D-amino acids (a series of peptides denoted as P01-P07) using parent 4B8M as a reference compound. In addition, diverse available bioinformatics tools using machine learning and artificial intelligence were tested to find the bio-pharmacokinetic and polypharmacological attributes of analyzed stereomers. All peptides were non-toxic to human peripheral blood mononuclear cells (PBMCs) and only cyclo-[D-Pro-Pro-β3-HoPhe-Phe-] peptide (P03) was capable of inhibiting mitogen-induced PBMC proliferation. The peptides inhibited the lipopolysaccharide (LPS)-induced production of tumor necrosis factor-alpha (TNF-α) to various degrees, with P04 (cyclo-[Pro-Pro-D-β3-HoPhe-Phe-]) and P03 being the most potent. For further in vivo studies, P03 was selected because it had the combined properties of inhibiting cell proliferation and TNF-α production. P03 demonstrated a comparable ability to 4B8M in the inhibition of auricle edema and lymph node cell number and in the normalization of a distorted blood cell composition in contact sensitivity to the oxazolone mouse model. In the mouse model of carrageenan-induced inflammation of the air pouch, P03 exhibited a similar inhibition of the cell number in the air pouches as 4B8M, but its inhibitory effects on the percentage of neutrophils and eosinophils in the air pouches and blood, as well as on mastocyte degranulation in the air pouches, were stronger in comparison to 4B8M. Lastly, in a mouse model of dextran sulfate-induced colitis, similar effects to 4B8M regarding thymocyte number restoration and normalization of the blood cell pictures by P03 were observed. In summary, depending on either experimental findings or in silico predictions, P03 demonstrated comparable, or even better, anti-inflammatory and bio-pharmacokinetic properties to 4B8M and may be considered as a potential therapeutic. The possibility of P00 and P03 identification by circular dichroism measurements was tested by quantum-chemical calculations.

Utility of pemafibrate in nonalcoholic steatohepatitis model mice induced by a choline-deficient, high-fat diet and dextran sulfate sodium

Aim

The purpose of this study was to examine the effect of pemafibrate in a murine model of non-alcoholic steatohepatitis (NASH).

Methods

Forty-two, 19-week-old, male, C57BL/6J mice were divided into three groups: a Control group (n = 14), a dextran sulfate sodium (DSS) group (n = 14), and a DSS + PEM group (n = 14). All mice were given a standard rodent diet for the first week, followed by a choline-deficient, high-fat diet (CDHF) for the next 12 weeks. The 22nd day after the animals arrived was taken as Day 1 of the experiment. The Control group continued the CDHF diet and MilliQ water. The DSS group continued the CDHF diet, but starting on Day 1, the group received 0.8 % DSS to drink for 7 consecutive days, followed by MilliQ water for 10 days; this was taken as one course, and it was repeated on the same schedule until autopsy. The DSS + PEM group received the CDHF diet with PEM 0.1 mg/kg/day. Their drinking water was the same as that of the DSS group. On Seven animals from each group were autopsied on each of Day 50 and Day 120, and histopathological and immunohistochemical examinations, as well as quantitative RNA and cytokine measurements, of autopsied mice were performed.

Results

Pemafibrate improved hepatic steatosis (decreased steatosis area), improved liver inflammation enhanced by DSS (decreased aspartate transaminase and alanine aminotransferase), improved hepatic fibrosis promoted by DSS (decreased fibrotic areas and a marker of fibrosis), inhibited tumorigenesis, and decreased intestinal inflammation in the NASH model mice.

Conclusions

In a murine model of NASH, mixing PEM 0.1 mg/kg/day into the diet inhibited disease progression and tumor formation.

An overview on the cellular mechanisms of anthocyanins in maintaining intestinal integrity and function

Structural and functional changes of the intestinal barrier, as a consequence of a number of (epi)genetic and environmental causes, have a main role in penetrations of pathogens and toxic agents, and lead to the development of inflammation-related pathological conditions, not only at the level of the GI tract but also in other extra-digestive tissues and organs. Anthocyanins (ACNs), a subclass of polyphenols belonging to the flavonoid group, are well known for their health-promoting properties and are widely distributed in the human diet. There is large evidence about the correlation between the human intake of ACN-rich products and a reduction of intestinal inflammation and dysfunction. Our review describes the more recent advances in the knowledge of cellular and molecular mechanisms through which ACNs can modulate the main mechanisms involved in intestinal dysfunction and inflammation, in particular the inhibition of the NF-κB, JNK, MAPK, STAT3, and TLR4 proinflammatory pathways, the upregulation of the Nrf2 transcription factor and the expression of tight junction proteins and mucins.

Artificial intelligence generated clinical score sheets: looking at the two faces of Janus

In vivo experiments are increasingly using clinical score sheets to ensure minimal distress to the animals. A score sheet is a document that includes a list of specific symptoms, behaviours and intervention guidelines, all balanced to for an objective clinical assessment of experimental animals. Artificial Intelligence (AI) technologies are increasingly being applied in the field of preclinical research, not only in analysis but also in documentation processes, reflecting a significant shift towards more technologically advanced research methodologies. The present study explores the application of Large Language Models (LLM) in generating score sheets for an animal welfare assessment in a preclinical research setting. Focusing on a mouse model of inflammatory bowel disease, the study evaluates the performance of three LLM - ChatGPT-4, ChatGPT-3.5, and Google Bard - in creating clinical score sheets based on specified criteria such as weight loss, stool consistency, and visible fecal blood. Key parameters evaluated include the consistency of structure, accuracy in representing severity levels, and appropriateness of intervention thresholds. The findings reveal a duality in LLM-generated score sheets: while some LLM consistently structure their outputs effectively, all models exhibit notable variations in assigning numerical values to symptoms and defining intervention thresholds accurately. This emphasizes the dual nature of AI performance in this field-its potential to create useful foundational drafts and the critical need for professional review to ensure precision and reliability. The results highlight the significance of balancing AI-generated tools with expert oversight in preclinical research.

Unveiling Colitis: A Journey through the Dextran Sodium Sulfate-induced Model

Animal models of inflammatory bowel disease (IBD) are valuable tools for investigating the factors involved in IBD pathogenesis and evaluating new therapeutic options. The dextran sodium sulfate (DSS)-induced model of colitis is arguably the most widely used animal model for studying the pathogenesis of and potential treatments for ulcerative colitis (UC), which is a primary form of IBD. This model offers several advantages as a research tool: it is highly reproducible, relatively easy to generate and maintain, and mimics many critical features of human IBD. Recently, it has also been used to study the role of gut microbiota in the development and progression of IBD and to investigate the effects of other factors, such as diet and genetics, on colitis severity. However, although DSS-induced colitis is the most popular and flexible model for preclinical IBD research, it is not an exact replica of human colitis, and some results obtained from this model cannot be directly applied to humans. This review aims to comprehensively discuss different factors that may be involved in the pathogenesis of DSS-induced colitis and the issues that should be considered when using this model for translational purposes.

Engaging natural antibody responses for the treatment of inflammatory bowel disease via phosphorylcholine-presenting nanofibres

Inflammatory bowel disease lacks a long-lasting and broadly effective therapy. Here, by taking advantage of the anti-infection and anti-inflammatory properties of natural antibodies against the small-molecule epitope phosphorylcholine (PC), we show in multiple mouse models of colitis that immunization of the animals with self-assembling supramolecular peptide nanofibres bearing PC epitopes induced sustained levels of anti-PC antibodies that were both protective and therapeutic. The strength and type of immune responses elicited by the nanofibres could be controlled through the relative valency of PC epitopes and exogenous T-cell epitopes on the nanofibres and via the addition of the adjuvant CpG. The nanomaterial-assisted induction of the production of therapeutic antibodies may represent a durable therapy for inflammatory bowel disease.

Ketogenic Diet Protects from Experimental Colitis in a Mouse Model Regardless of Dietary Fat Source

While ketogenic diets (KDs) may have potential as adjunct treatments for gastrointestinal diseases, there is little knowledge on how the fat source of these diets impacts intestinal health. The objective of this study was to investigate how the source of dietary fat of KD influences experimental colitis. We fed nine-week-old male C57BL/6J mice (n = 36) with a low-fat control diet or KD high either in saturated fatty acids (SFA-KD) or polyunsaturated linoleic acid (LA-KD) for four weeks and then induced colitis with dextran sodium sulfate (DSS). To compare the diets, we analyzed macroscopic and histological changes in the colon, intestinal permeability to fluorescein isothiocyanate-dextran (FITC-dextran), and the colonic expression of tight junction proteins and inflammatory markers. While the effects were more pronounced with LA-KD, both KDs markedly alleviated DSS-induced histological lesions. LA-KD prevented inflammation-related weight loss and the shortening of the colon, as well as preserved Il1b and Tnf expression at a healthy level. Despite no significant between-group differences in permeability to FITC-dextran, LA-KD mitigated changes in tight junction protein expression. Thus, KDs may have preventive potential against intestinal inflammation, with the level of the effect being dependent on the dietary fat source.

Selection of Fermentation Supernatant from Probiotic Strains Exhibiting Intestinal Epithelial Barrier Protective Ability and Evaluation of Their Effects on Colitis Mouse and Weaned Piglet Models

The intestinal epithelial barrier can prevent the invasion of pathogenic microorganisms and food antigens to maintain a consistent intestinal homeostasis. However, an imbalance in this barrier can result in various diseases, such as inflammatory bowel disease, malnutrition, and metabolic disease. Thus, the aim of this study was to select probiotic strains with epithelial barrier-enhancing ability in cell-based model and further investigate them for their improving effects on colitis mouse and weaned piglet models. The results showed that selected specific cell-free fermentation supernatants (CFSs) from Ligilactobacillus salivarius P1, Lactobacillus gasseri P12, and Limosilactobacillus reuteri G7 promoted intestinal epithelial cell growth and proliferation, strengthening the intestinal barrier in an intestinal epithelial cell line Caco-2 model. Further, the administration of CFSs of L. salivarius P1, L. gasseri P12, and L. reuteri G7 were found to ameliorate DSS-induced colitis in mice. Additionally, spray-dried powders of CFS from the three strains were examined in a weaned piglet model, only CFS powder of L. reuteri G7 could ameliorate the feed/gain ratio and serum levels of D-lactate and endotoxin. In conclusion, a new potential probiotic strain, L. reuteri G7, was selected and showed ameliorating effects in both colitis mouse and weaned piglet models.

Early Growth Response Protein 1 Exacerbates Murine Inflammatory Bowel Disease by Transcriptional Activation of Matrix Metalloproteinase 12

Inflammatory bowel disease (IBD) is an inflammatory condition affecting the colon and small intestine, with Crohn's disease and ulcerative colitis being the major types. Individuals with long-term IBD are at an increased risk of developing colorectal cancer. Early growth response protein 1 (Egr1) is a nuclear protein that functions as a transcriptional regulator. Egr1 is known to control the expression of numerous genes and play a role in cell growth, proliferation, and differentiation. While IBD has been associated with severe inflammation, the precise mechanisms underlying its pathogenesis remain unclear. This study aimed to investigate the role of Egr1 in the development of IBD. High levels of Egr1 expression were observed in a mouse model of colitis induced by dextran sulfate sodium (DSS), as determined by immunohistochemical (IHC) staining. Chronic DSS treatment showed that Egr1 knockout (KO) mice exhibited resistance to the development of IBD, as determined by changes in their body weight and disease scores. Additionally, enzyme-linked immunosorbent assay (ELISA) and IHC staining demonstrated decreased expression levels of proinflammatory cytokines such as IL-1β, IL-6, and TNF-α, as well as matrix metalloproteinase 12 (MMP12). Putative Egr1 binding sites were identified within the MMP12 promoter region. Through reporter assays and chromatin immunoprecipitation (ChIP) analysis, it was shown that Egr1 binds to the MMP12 promoter and regulates MMP12 expression. In conclusion, we found that Egr1 plays a role in the inflammation process of IBD through transcriptionally activating MMP12.

Sterols in Inflammatory Diseases: Implications and Clinical Utility

The characteristic steroid skeleton, with its 4-ringed 17-carbon structure, is one of the most recognizable organic compounds in biochemistry. In the presence of a hydroxyl ion bound to the third carbon, this structure is defined as a "sterol" (chemical formula: C17H28O). The hydroxyl group provides a hydrophilic site for the otherwise hydrophobic molecule, yielding an amphipathic lipid, which is a vital property for cellular function. It is crucial to remark that the term "steroid" describes a larger group of compounds that often retain the hydroxyl group but are primarily characterized by methyl groups, double bonds in the rings, and an aliphatic side-chain extending from the 17th carbon. In addition to serving various structural roles in the cellular membrane, sterols and steroids contribute to cellular and systemic functions as messengers, hormones, and regulators of several critical metabolic pathways.Sterol nomenclature is often confusing, partly due to structural complexity and partly due to the sheer number of different compounds that fall under the definition. Fortunately, the foremost sterols of interest in biochemistry are much fewer, and therefore, these lipids have been defined and studied vigorously. With the renaissance of lipid research during the 1990s and 2000s, many different metabolites of sterols, and more specifically phytosterols, were found to be associated with various diseases and conditions, including cardiovascular disease, hypercholesterolemia, cancer, obesity, inflammation, diabetes, and inborn errors of metabolism; thus, it is evident that the ever-evolving research in this field has been, and will continue to be, exceedingly productive.With respect to inflammation and inflammatory diseases, plant-based sterols (i.e., phytosterols) have gained considerable fame due to their anti-inflammatory and cholesterol-lowering effects demonstrated by experimental and clinical research. Besides, the exceptional pharmacological benefits of these sterols, which operate as antioxidant, antidiabetic, and anti-atherosclerotic agents, have been the subject of various investigations. While the underlying mechanisms necessitate further research, the possible function of phytosterols in improving health outcomes is an important topic to explore.In this regard, the current review aims to offer comprehensive information on the therapeutic potential of plant-based sterols in the context of human health, with a focus on preclinical effects, bioavailability, and clinical use.

Fermented rice bran supplementation attenuates colonic injury through modulating intestinal aryl hydrocarbon receptor and innate lymphoid cells in mice with dextran sodium sulfate-induced acute colitis

This study investigated the effects of fermented rice bran (FRB) on modulating intestinal aryl hydrocarbon receptor (AhR) expression, innate lymphoid cell (ILC)3 populations, the fecal microbiota distribution, and their associations with dextran sodium sulfate (DSS)-induced acute colitis. C57BL/6 mice were assigned to four groups: 1) NC group, normal mice fed the AIN-93M diet; 2) FRB group, normal mice fed a diet supplemented with 5% FRB; 3) NCD group, DSS-treated mice fed AIN-93M; 4) FRBD group, DSS-treated mice fed a 5% FRB-supplemented diet. DSS was administered for 5 d and followed by 5 d for recovery. At the end of the experiment, mice were sacrificed. Their blood and intestinal tissues were collected. Results showed that there were no differences in colonic biological parameters and function between the NC and FRB groups. Similar fecal microbiota diversity was noted between these two groups. Compared to the non-DSS-treated groups, DSS administration led to increased intestinal permeability, enhanced inflammatory cytokine production and disease severity, whereas tight junctions and AhR, interleukin (IL)-22 expressions were downregulated, and the ILC3 population had decreased. Also, gut microbiota diversity differs from the non-DSS-treated groups and more detrimental bacterial populations exist when compared to the FRBD group. FRB supplementation in DSS-treated mice attenuated fecal microbial dysbiosis, decreased intestinal permeability, improved the barrier integrity, upregulated AhR and IL-22 expression, maintained the ILC3 population, and pathologically mitigated colonic injury. These findings suggest enhanced ILC3- and AhR-mediated functions may be partly responsible for the anti-colitis effects of FRB supplementation in DSS-induced colitis.

DSS treatment does not affect murine colonic microbiota in absence of the host

The prevalence of inflammatory bowel disease (IBD) is rising globally; however, its etiology is still not fully understood. Patient genetics, immune system, and intestinal microbiota are considered critical factors contributing to IBD. Preclinical animal models are crucial to better understand the importance of individual contributing factors. Among these, the dextran sodium sulfate (DSS) colitis model is the most widely used. DSS treatment induces gut inflammation and dysbiosis. However, its exact mode of action remains unclear. To determine whether DSS treatment induces pathogenic changes in the microbiota, we investigated the microbiota-modulating effects of DSS on murine microbiota in vitro. For this purpose, we cultured murine microbiota from the colon in six replicate continuous bioreactors. Three bioreactors were supplemented with 1% DSS and compared with the remaining PBS-treated control bioreactors by means of microbiota taxonomy and functionality. Using metaproteomics, we did not identify significant changes in microbial taxonomy, either at the phylum or genus levels. No differences in the metabolic pathways were observed. Furthermore, the global metabolome and targeted short-chain fatty acid (SCFA) quantification did not reveal any DSS-related changes. DSS had negligible effects on microbial functionality and taxonomy in vitro in the absence of the host environment. Our results underline that the DSS colitis mouse model is a suitable model to study host-microbiota interactions, which may help to understand how intestinal inflammation modulates the microbiota at the taxonomic and functional levels.

Utility of ultrasonography in a mouse model of non-alcoholic steatohepatitis induced by a choline-deficient, high-fat diet and dextran sulfate sodium

Background

Nonalcoholic steatohepatitis (NASH) is a chronic progressive liver disease that can progress to cirrhosis and hepatocellular carcinoma. The prevalence of NASH is increasing year by year. However, the etiology and progression of NASH, along with the processes leading to carcinogenesis, remain poorly understood. A range of animal models are used in research, but investigators have been unable to establish a model that results in tumorigenesis from a stable disease state. The present study aimed to create a stable, low-mortality model of NASH using abdominal ultrasonography (US) to assess NASH stage and diagnose liver tumors.

Methods

Thirty-four 19-week-old male C57BL/6J mice were fed a choline-deficient, high-fat (CDHF) diet. Twenty animals were given seven courses of 0.8 % dextran sulfate sodium (DSS) for 7 days followed by 10 days of MilliQ water (CDHF+DSS group). The remaining 14 animals drank only MilliQ water (CDHF group). All animals were weighed weekly and US was performed on Days 35 and 120. After necropsy, samples were taken for biochemical analysis and histopathological evaluation.

Results

The CDHF+DSS group had significantly lower body weight on Days 35 and 120, and significantly higher liver/body weight (%) on Day 35 compared to the CDHF group. US on Days 35 and 120 revealed significantly shorter long intestine and higher colonic histological score in the CDHF+DSS group compared to the CDHF group. IL-1β and IL-6 levels in the large intestinal tissue were significantly higher in the CDHF+DSS group.

Conclusions

A stable, low-mortality model of NASH was created with a CDHF diet and intermittent 0.8 % DSS. Abdominal US can assess the degree of fatty degeneration and evaluate liver tumorigenesis without necropsy. This assessment procedure will reduce the number of mice killed unnecessarily during experiments, thereby contributing to animal welfare.

C4BP(β-)-mediated immunomodulation attenuates inflammation in DSS-induced murine colitis and in myeloid cells from IBD patients

The most recent and promising therapeutic strategies for inflammatory bowel disease (IBD) have engaged biologics targeting single effector components involved in major steps of the immune-inflammatory processes, such as tumor necrosis factor, interleukins or integrins. Nevertheless, these molecules have not yet met expectations regarding efficacy and safety, resulting in a significant percentage of refractory or relapsing patients. Thus, novel treatment options are urgently needed. The minor isoform of the complement inhibitor C4b-binding protein, C4BP(β-), has been shown to confer a robust anti-inflammatory and immunomodulatory phenotype over inflammatory myeloid cells. Here we show that C4BP(β-)-mediated immunomodulation can significantly attenuate the histopathological traits and preserve the intestinal epithelial integrity in dextran sulfate sodium (DSS)-induced murine colitis. C4BP(β-) downregulated inflammatory transcripts, notably those related to neutrophil activity, mitigated circulating inflammatory effector cytokines and chemokines such as CXCL13, key in generating ectopic lymphoid structures, and, overall, prevented inflammatory immune cell infiltration in the colon of colitic mice. PRP6-HO7, a recombinant curtailed analogue with only immunomodulatory activity, achieved a similar outcome as C4BP(β-), indicating that the therapeutic effect is not due to the complement inhibitory activity. Furthermore, both C4BP(β-) and PRP6-HO7 significantly reduced, with comparable efficacy, the intrinsic and TLR-induced inflammatory markers in myeloid cells from both ulcerative colitis and Crohn's disease patients, regardless of their medication. Thus, the pleiotropic anti-inflammatory and immunomodulatory activity of PRP6-HO7, able to "reprogram" myeloid cells from the complex inflammatory bowel environment and to restore immune homeostasis, might constitute a promising therapeutic option for IBD.

Genetic and Pharmacological Blockade of Sigma-1 Receptors Attenuates Inflammation-Associated Hypersensitivity during Acute Colitis in CD1 Mice

Sigma-1 receptors (σ1Rs) are implicated in nociception, including pain sensitization, and inflammation. We assessed the role of σ1Rs on acute colitis-associated hypersensitivity using both genetic (constitutive knockout) and pharmacological blockade of the receptor. Colitis was induced in CD1 wild-type (WT) and σ1R KO mice (exposure to dextran sodium sulfate, 3%). A von Frey test was used to assess referred mechanosensitivity (abdominal and plantar withdrawal responses). The effects of the selective σ1R antagonists BD1063 and E-52862 were also assessed in WT animals. The expression of immune and sensory-related markers (RT-qPCR, Western blot) was assessed in the colon and lumbosacral spinal cord. The genetic ablation or pharmacological blockade of σ1Rs attenuated acute colonic inflammation in a similar manner. Mechanosensitivity was similar in WT and σ1R KO mice before colitis. In WT mice, but not in σ1R KO, colitis was associated with the development of referred mechanical hypersensitivity, manifested as a reduction in the withdrawal thresholds to mechanical probing (paw and abdominal wall). In WT mice, BD1063 and E-52862 blocked colitis-associated hypersensitivity. A genotype- and treatment-related differential regulation of sensory-related markers was detected locally (colon) and within the spinal cord. σ1Rs are involved in the development of acute intestinal inflammation and its associated referred mechanical hypersensitivity. The selective modulation of sensory-related pathways within the colon and spinal cord might be part of the underlying mechanisms. These observations support the pharmacological use of σ1R antagonists for the treatment of intestinal inflammation-induced hypersensitivity.

Evaluation of a Standardized Extract Obtained from Cashew Apple (Anacardium occidentale L.) Bagasse in DSS-Induced Mouse Colitis

Inflammatory bowel diseases (IBD) include Crohn's disease and ulcerative colitis. Several studies relate eating habits to different aspects of IBD, such as progression and worsening of the clinical condition. Therefore, many natural products (NPs) such as polyphenols and carotenoids have been identified as promising agents in supporting IBD. An interesting source for obtaining bioactive NPs is the by-products of the food industry. The present study evaluated the potential beneficial effect of a standardized extract (CAE) obtained from cashew apple bagasse in the dextran sulfate sodium (DSS)-induced ulcerative colitis model in mice. This was the first time that CAE had been evaluated in this experimental model. Chemical evaluation of CAE identified carotenoids (96.28 ± 0.15 mg/100 g), phenolic compounds (37.49 ± 0.64 mg/100 g), and a mixture of anacardic acids (C15:3 = 94.2 ± 0.6 mg/100 g; C15:2 = 108.4 ± 0.1 mg/100 g; C15:1 = 214.8 ± 0.2 mg/100 g). Administration of CAE (500 mg/kg, 4 days, p.o.) after DSS challenge was more effective in delaying disease progression compared with prior treatment (500 mg/kg, 30 days, p.o.), according to the disease activity index. However, no treatment strategy with CAE was able to prevent or inhibit disease progression, since all parameters evaluated (macroscopic, biochemical, and histopathological) in CAE-treated animals were similar to those observed in DSS-challenged animals. Despite the high dose (500 mg/kg), the standardized extract (CAE) did not result in an effective concentration of carotenoids. Furthermore, as some anacardic acids have been reported as histone acetyltransferases inhibitors, there could be a possible antagonistic relationship between carotenoids and anacardic acids. Complementary research will be necessary to test the hypothesis of antagonism. Thus, an optimized extract, with an even higher concentration of carotenoids, obtained from cashew apple bagasse, can be developed as a possible adjuvant food supplement for inflammatory bowel diseases.

Investigations of the gingerol oil colon targeting pellets for the treatment of ulcerative colitis

The clinical treatment of ulcerative colitis (UC) faces great challenges due to lifetime medication. In this study, Gingerol oil was extracted and purified by the process easily scale-up and cost effective, with productivity 2.72 ± 0.38% (w/w, versus crude drugs). The quality control of gingerol oil was fully established by HPLC fingerprint with 4 common peaks identified as 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol. The similarities of 6 batches of gingerol oil are within 0.931-0.999. The protective effects of gingerol oil are equivalent to or even stronger than that of 6-gingerol on inflammation and oxidative stress of HT-29 cells induced by lipopolysaccharide and H2O2, as well as on UC in mice caused by dextran sulfate sodium salt (DSS). Our research conclusions coincide well with the holistic view of Traditional Chinese Medicine and network pharmacology. The absorption kinetics of gingerol oil were conducted using the in situ intestinal perfusion in rats and comparable absorption were achieved in the jejunum, ileum and colon segments within 2 h. Thus, gingerol oil colon targeting pellets were prepared by extrusion-spherization technique. The cumulative dissolution behaviors and mechanisms were observed and analyzed by fitting to dissolution model. Our studies provided reliable theoretical and experimental support for the gingerol oil as reliable therapeutic choice of UC.

Adverse effects of an aldosterone synthase (CYP11B2) inhibitor, fadrozole (FAD286), on inflamed rat colon

Recently, we described local aldosterone production in the murine large intestine. Upregulated local aldosterone synthesis in different tissues has been linked with inflammatory conditions, which have been attenuated by the aldosterone synthase (CYP11B2) inhibitor, fadrozole (FAD286). Therefore, we investigated the effect of inhibition of intestinal aldosterone synthesis on the development of intestinal inflammation. Sprague-Dawley rats were administered 5% (v/w) dextran sodium sulphate (DSS) for 7 days with or without daily FAD286 (30 mg/kg/d) subcutaneous injections on 3 days before, during and one day after DSS. Tissue aldosterone concentrations were evaluated by ELISA, CYP11B2 by Western blot and RT-qPCR. FAD286 halved adrenal aldosterone production but, intriguingly, increased the colonic aldosterone concentration. The lack of inhibitory effect of FAD286 in the colon might have been affected by the smaller size of colonic vs. adrenal CYP11B2, as seen in Western blot. When combined with DSS, FAD286 aggravated the macroscopic and histological signs of intestinal inflammation, lowered the animals' body weight gain and increased the incidence of gastrointestinal bleeding and the permeability to iohexol in comparison to DSS-animals. To conclude, FAD286 exerted harmful effects during intestinal inflammation. Local intestinal aldosterone did not seem to play any role in the inflammatory pathogenesis occurring in the intestine.

An oral cholera vaccine in the prevention and/or treatment of inflammatory bowel disease

The oral cholera vaccine WC-rBS consists of 4 different inactivated strains of Vibrio cholerae (LPS source) admixed with recombinant cholera toxin B subunit. Because of its unique composition and anti-inflammatory properties reported for both CTB and low doses of LPS from other Gram-negative bacteria, we speculated that WC-rBS might have anti-inflammatory potential in a chronic autoimmune disease such as inflammatory bowel diseases. First in vitro endotoxin tolerance experiments showed the surprising WC-rBS potential in the modulation of inflammatory responses on both PBMCs and THP1 cells. WC-rBS was further evaluated in the Dextran Sodium Sulfate colitis mouse model. Administrated orally at different dosages, WC-rBS vaccine was safe and showed immunomodulatory properties when administered in a preventive mode (before and during the induction of DSS colitis) as well as in a curative mode (after colitis induction); with improvement of disease activity index (from 27 to 73%) and histological score (from 65 to 88%). Interestingly, the highest therapeutic effect of WC-rBS vaccine was observed with the lowest dosage, showing even better anti-inflammatory properties than mesalamine; an approved 5-aminosalicylic acid drug for treating IBD patients. In summary, this is the first time that a prophylactic medicine, safe and approved for prevention of an infectious disease, showed a benefit in an inflammatory bowel disease model, potentially offering a novel therapeutic modality for IBD patients.

Hydroethanolic Extract of Fritillariae thunbergii Bulbus Alleviates Dextran Sulfate Sodium-Induced Ulcerative Colitis by Enhancing Intestinal Barrier Integrity

The incidence of ulcerative colitis (UC), an inflammatory disorder of the gastrointestinal tract, has rapidly increased in Asian countries over several decades. To overcome the limitations of conventional drug therapies, including biologics for UC management, the development of herbal medicine-derived products has received continuous attention. In this study, we evaluated the beneficial effects of a hydroethanolic extract of Fritillariae thunbergii Bulbus (FTB) in a mouse model of DSS-induced UC. The DSS treatment successfully induced severe colonic inflammation and ulceration. However, the severity of colitis was reduced by the oral administration of FTB. Histopathological examination showed that FTB alleviated the infiltration of inflammatory cells (e.g., neutrophils and macrophages), damage to epithelial and goblet cells in the colonic mucosal layer, and fibrotic lesions. Additionally, FTB markedly reduced the gene expression of proinflammatory cytokines and extracellular matrix remodeling. Immunohistochemical analysis showed that FTB alleviated the decrease in occludin and zonula occludens-1 expression induced by DSS. In a Caco-2 monolayer system, FTB treatment improved intestinal barrier permeability in a dose-dependent manner and increased tight junction expression. Overall, FTB has potential as a therapeutic agent through the improvement of tissue damage and inflammation severity through the modulation of intestinal barrier integrity.

Amelioration of Murine Colitis by Attenuated Salmonella choleraesuis Encoding Interleukin-19

The imbalance of mucosal immunity in the lower gastrointestinal tract can lead to chronic inflammatory bowel diseases (IBDs), including Crohn's disease and ulcerative colitis. IBD is a chronic inflammatory disorder that causes small and/or large intestines ulceration. According to previous studies, recombinant interleukin (IL)-10 protein and genetically modified bacteria secreting IL-10 ameliorate dextran sulfate sodium (DSS)-induced colitis in mice. IL-19 is a transcriptional activator of IL-10 and can alter the balance of T helper 1 (Th)1/Th2 cells in favor of Th2. In this study, we aimed to investigate whether the expression of the murine IL-19 gene carried by Salmonella choleraesuis (S. choleraesuis) could ameliorate murine IBD. Our results showed that the attenuated S. choleraesuis could carry and express the IL-19 gene-containing plasmid for IBD gene therapy by reducing the mortality and clinical signs in DSS-induced acute colitis mice as compared to the untreated ones. We also found that IL-10 expression was induced in IL-19-treated colitis mice and prevented inflammatory infiltrates and proinflammatory cytokine expression in these mice. We suggest that S. choleraesuis encoding IL-19 provides a new strategy for treating IBD in the future.

Immunomodulatory effects of different strains of Lactococcus lactis in DSS-induced colitis

Inflammatory bowel diseases (IBD) are gastrointestinal disorders characterized by a breakdown in intestinal homeostasis by inflammatory immune responses to luminal antigens. Novel strategies for ameliorating IBD have been proposed in many studies using animal models. Our group has demonstrated that administration of Lactococcus lactis NCDO 2118 can improve clinical parameters of colitis induced by oral administration of dextran sulphate sodium (DSS). However, it is not clear whether other strains of L. lactis can yield the same effect. The objective of present study was to analyze the effects of three different L. lactis strains (NCDO2118, IL1403 and MG1363) in the development of DSS-induced colitis in C57BL/6 mice. Acute colitis was induced in C57/BL6 mice by the administration of 2% DSS during 7 consecutive days. Body weight loss and shortening of colon length were observed in DSS-treated mice, and none of L. lactis strains had an impact in these clinical signs of colitis. On the other hand, all strains improved the global macroscopical disease index and prevented goblet cells depletion as well as the increase of intestinal permeability. TNF-α production was reduced in gut mucosa of L. lactis DSS-treated mice indicating a modulation of a critical pro-inflammatory response by all strains tested. However, only L. lactis NCDO2118 and MG1363 induced a higher frequency of CD11c+CD11b-CD103+ tolerogenic dendritic cells in lymphoid organs of mice at steady state. We conclude that all tested strains of L. lactis improved the clinical scores and parameters of colitis, which confirm their anti-inflammatory properties in this model of colitis.

Slc11a1 gene polymorphism influences dextran sulfate sodium (DSS)-induced colitis in a murine model of acute inflammation

Ulcerative Colitis (UC) is an inflammatory disease characterized by colonic mucosal lesions associated with an increased risk of carcinogenesis. UC pathogenesis involves environmental and genetic factors. Genetic studies have indicated the association of gene variants coding for the divalent metal ion transporter SLC11A1 protein (formerly NRAMP1) with UC susceptibility in several animal species. Two mouse lines were genetically selected for high (AIRmax) or low (AIRmin) acute inflammatory responses (AIR). AIRmax is susceptible, and AIRmin is resistant to DSS-induced colitis and colon carcinogenesis. Furthermore, AIRmin mice present polymorphism of the Slc11a1 gene. Here we investigated the possible modulating effect of the Slc11a1 R and S variants in DSS-induced colitis by using AIRmin mice homozygous for Slc11a1 R (AIRmin^RR) or S (AIRmin^SS) alleles. We evaluated UC by the disease activity index (DAI), considering weight loss, diarrhea, blood in the anus or feces, cytokines, histopathology, and cell populations in the distal colon epithelium. AIRmin^SS mice have become susceptible to DSS effects, with higher DAI, IL6, G-CSF, and MCP-1 production and morphological and colon histopathological alterations than AIRmin^RR mice. The results point to a role of the Slc11a1 S allele in DSS colitis induction in the genetic background of AIRmin mice.

Akkermansia muciniphila plays critical roles in host health

Akkermansia muciniphila, an intestinal microorganism, belongs to Verrucomicrobia, one of the most abundant microorganisms in the mammalian gut. It is a mucin-degrading bacterium that can colonise intestines of mammals such as humans and mice by utilising mucin as the only nitrogen and carbon source. When A. muciniphila colonises the intestine, its metabolites interact with the intestinal barrier, affecting host health by consolidating the intestinal barrier, regulating metabolic functions of the intestinal and circulatory systems, and regulating immune functions. This review summarised the mechanisms of A. muciniphila-host interactions that are relevant to host health. We focussed on characteristics of A. muciniphila in relation to its metabolites to provide a comprehensive understanding of A. muciniphila and its effects on host health and disease processes.

Mitotic spindle positioning protein (MISP) deficiency exacerbates dextran sulfate sodium (DSS)-induced colitis in mice

Inflammatory bowel disease (IBD) is classified into two types: Crohn's disease and ulcerative colitis. In IBD, the imbalance between the pro-inflammatory and anti-inflammatory cytokines prevents recovery from the inflammatory state, resulting in chronic inflammation in the colon. The mitotic spindle positioning protein (MISP) is localized to the apical membrane in the colon. In this study, we observed increased expression of MISP in the intestinal epithelial cells in dextran sulfate sodium (DSS)-induced colitis in mice. MISP-deficient mice receiving DSS showed significant exacerbation of colitis (e.g., weight loss, loss of the crypts). The intestinal epithelial cells of the MISP-deficient mice showed a trend towards decreased cell proliferation after DSS treatment. Reverse transcription followed by quantitative polymerase chain reaction revealed that the expression levels of Tgfb1, an anti-inflammatory cytokine, were significantly reduced in the colon of MISP-deficient mice compared with the wild-type mice regardless of DSS treatment. These findings indicate that MISP may play a role in the recovery of the colon after inflammation through its anti-inflammatory and proliferative activities, suggesting that MISP may be a new therapeutic target for IBD.

Transgenerational impacts of oral probiotic administration in pregnant mice on offspring gut immune cells and colitis susceptibility

BACKGROUND AND AIM

The study of the impact of environmental factors during pregnancy on fetal development has so far been focused primarily on those negatively affecting human health; however, little is known about the effects of probiotic treatment during pregnancy on inflammatory bowel diseases (IBD). In this study, we investigated whether oral administration of heat-killed probiotics isolated from fermented foods decreased the vulnerability of offspring to IBD.

METHODS

Probiotics were administered to the pregnant mice until the birth of pups, after which the parent mice were maintained with autoclaved water. Partial pups were evaluated for dextran sodium sulfate-induced colitis. The influence of CD11c⁺ CD103⁺ dendritic cells (DCs) and regulatory T cells (Tregs) in mesenteric lymph nodes of parent mice and their pups was analyzed.

RESULTS

Oral administration of heat-killed probiotics to pregnant dams significantly decreased inflammation induced by dextran sodium sulfate in pups. Probiotic treatment increased the number of CD103⁺ DCs, and the expression of β8-integrin in CD103⁺ DCs and Tregs in mesenteric lymph nodes, not only in dams themselves but also in their offspring.

CONCLUSIONS

Oral administration of probiotics during gestation induced transgenerational immunomodulatory effects on the gut-associated immune system and resilience to experimental colitis in the offspring. Our results suggest that consumption of fermented foods during pregnancy can be effective in preventing inflammatory diseases such as IBD beyond generation.

Nematode-Induced Growth Factors Related to Angiogenesis in Autoimmune Disease Attenuation

Accumulating data suggest an important role of growth factors in autoimmune diseases and parasitic nematode infections. Nematodes are used in clinical studies of autoimmune diseases and parasite-derived molecules are widely studied for their therapeutic potential in various types of disorders. However, the effect of nematode infection on growth factors in autoimmune disorders has not been studied. The objective of this study was to evaluate the influence of infection with the intestinal nematode Heligmosomoides polygyrus in murine autoimmune models on the production of growth factors. Here, the level of a variety of growth factors related mainly to angiogenesis was evaluated by protein array in the intestinal mucosa of C57BL/6 dextran sodium sulfate-induced colitic mice and in cerebral spinal fluid of experimental autoimmune encephalomyelitis (EAE) mice infected with nematodes. In addition, vessel formation was evaluated in the brains of EAE mice infected with H. polygyrus. A significant influence of nematode infection on the level of angiogenic factors was observed. Parasitic infection of colitic mice resulted in upregulation of mucosal AREG, EGF, FGF-2, and IGFBP-3 in the intestine of the host and better adaptation (infectivity). In EAE mice, infection increased the level of FGF-2 and FGF-7 in CSF. In addition, remodeling of brain vessels was observed, with a higher density of long vessels. Nematode-derived factors are promising tools to fight autoimmune diseases and to study angiogenesis.

Algal oil alleviates antibiotic-induced intestinal inflammation by regulating gut microbiota and repairing intestinal barrier

Introduction

Taking antibiotics would interfere with gut microbiota and increase the risk of opportunistic pathogen infection and inflammation.

Methods

In this study, 36 male C57BL/6 mice were divided into 4 groups (n = 9) to investigate whether two kinds of algal oil could alleviate the intestinal damage induced by CS (Ceftriaxone sodium). These algal oils were obtained from Schizochytrium sp. cultures using Yeast extract (YE) and Rapeseed meal (RSM) as substrate, respectively. All tested mice were administrated with CS for 8 days and then the colon pathological morphology, the expression levels of inflammatory factors and the gut microbial profile were analyzed in mice supplemented with or without algal oil.

Results

The results showed that both YE and RSM algal oils markedly reduced mucosal damage and intestinal inflammatory response in CS-treated mice by inhibiting the pro-inflammatory cytokine tumor necrosis factor (TNF)-α, interleukin (IL)-6 and myeloperoxidase (MPO) activity. In addition, fluorescence immunohistochemistry showed that the tight junction protein ZO-1 was increased in mice supplemented with YE and RSM algal oil. Furthermore, YE algal oil promoted the beneficial intestinal bacteria such as Lachnospiraceae and S24_7 compared with the CS group, while supplementation with RSM algal oil enriched the Robinsoniella. Spearman's correlation analysis exhibited that Melissococcus and Parabacteroides were positively correlated with IL-6 but negatively correlated with IL-10.

Discussion

This study suggested that supplementation with algal oil could alleviate intestinal inflammation by regulating gut microbiota and had a protective effect on maintaining intestinal barrier against antibiotic-induced damage in mice.

An IBD-associated pathobiont synergises with NSAID to promote colitis which is blocked by NLRP3 inflammasome and Caspase-8 inhibitors

Conflicting evidence exists on the association between consumption of non-steroidal anti-inflammatory drugs (NSAIDs) and symptomatic worsening of inflammatory bowel disease (IBD). We hypothesized that the heterogeneous prevalence of pathobionts [e.g., adherent-invasive Escherichia coli (AIEC)], might explain this inconsistent NSAIDs/IBD correlation. Using IL10^-/- mice, we found that NSAID aggravated colitis in AIEC-colonized animals. This was accompanied by activation of the NLRP3 inflammasome, Caspase-8, apoptosis, and pyroptosis, features not seen in mice exposed to AIEC or NSAID alone, revealing an AIEC/NSAID synergistic effect. Inhibition of NLRP3 or Caspase-8 activity ameliorated colitis, with reduction in NLRP3 inflammasome activation, cell death markers, activated T-cells and macrophages, improved histology, and increased abundance of Clostridium cluster XIVa species. Our findings provide new insights into how NSAIDs and an opportunistic gut-pathobiont can synergize to worsen IBD symptoms. Targeting the NLRP3 inflammasome or Caspase-8 could be a potential therapeutic strategy in IBD patients with gut inflammation, which is worsened by NSAIDs.

Long-lasting visceral hypersensitivity in a model of DSS-induced colitis in rats

BACKGROUND

Persistent visceral hypersensitivity is a key component of functional and inflammatory gastrointestinal diseases. Current animal models fail to fully reproduce the characteristics of visceral pain in humans, particularly as it relates to persistent hypersensitivity. This work explores the validity of DSS-induced colitis in rats as a model to mimic chronic intestinal hypersensitivity.

METHODS

Exposure to DSS (5% for 7 days) was used to induce colitis in rats. Thereafter, changes in viscerosensitivity (visceromotor responses to colorectal distension-CRD), the presence of somatic referred pain (mechanosensitivity of the hind paws, von Frey test) and the expression (qRT-PCR) of sensory-related markers (colon, lumbosacral DRGs, and lumbosacral spinal cord) were assessed at different times during the 35 days period after colitis induction.

RESULTS

Following colitis, a sustained increase in visceromotor responses to CRD were observed, indicative of the presence of visceral hypersensitivity. Responses in animals without colitis remained stable over time. In colitic animals, somatic referred hypersensitivity was also detected. DSS-induced colitis was associated to a differential expression of sensory-related markers (with both pro- and anti-nociceptive action) in the colon, lumbosacral DRGs and lumbosacral spinal cord; indicating the presence of peripheral and central sensitization.

CONCLUSIONS AND INFERENCES

DSS-induced colitis in rats is associated to the generation of a long-lasting state of visceral (colonic) hypersensitivity, despite clinical colitis resolution. This model reproduces the changes in intestinal sensitivity characteristics of inflammatory and functional gastrointestinal disorders in humans and can be used in the characterization of new pharmacological treatments against visceral pain.

Impact of administration route on nanocarrier biodistribution in a murine colitis model

The incidence of inflammatory bowel disease (IBD) is increasing worldwide. Although current diagnostic and disease monitoring tests for IBD sensitively detect gut inflammation, they lack the molecular and cellular specificity of positron emission tomography (PET). In this proof-of-concept study, we use a radiolabeled macrophage-targeted nanocarrier probe (64Cu-NOTA-D500) administered by oral, enema, and intraperitoneal routes to evaluate the delivery route dependence of biodistribution across healthy and diseased tissues in a murine model of dextran sodium sulfate (DSS)-induced colitis. High inter-subject variability of probe uptake in intestinal tissue was reduced by normalization to uptake in liver or total intestines. Differences in normalized uptake between healthy and DSS colitis animal intestines were highest for oral and IP routes. Differences in absolute liver uptake reflected a possible secondary diagnostic metric of IBD pathology. These results should inform the preclinical development of inflammation-targeted contrast agents for IBD and related gut disorders to improve diagnostic accuracy.

Intestinal immune responses to commensal and pathogenic protozoa

The physical barrier of the intestine and associated mucosal immunity maintains a delicate homeostatic balance between the host and the external environment by regulating immune responses to commensals, as well as functioning as the first line of defense against pathogenic microorganisms. Understanding the orchestration and characteristics of the intestinal mucosal immune response during commensal or pathological conditions may provide novel insights into the mechanisms underlying microbe-induced immunological tolerance, protection, and/or pathogenesis. Over the last decade, our knowledge about the interface between the host intestinal mucosa and the gut microbiome has been dominated by studies focused on bacterial communities, helminth parasites, and intestinal viruses. In contrast, specifically how commensal and pathogenic protozoa regulate intestinal immunity is less well studied. In this review, we provide an overview of mucosal immune responses induced by intestinal protozoa, with a major focus on the role of different cell types and immune mediators triggered by commensal (Blastocystis spp. and Tritrichomonas spp.) and pathogenic (Toxoplasma gondii, Giardia intestinalis, Cryptosporidium parvum) protozoa. We will discuss how these various protozoa modulate innate and adaptive immune responses induced in experimental models of infection that benefit or harm the host.

Pla2g2a promotes innate Th2-type immunity lymphocytes to increase B1a cells

Newborns require early generation of effective innate immunity as a primary physiological mechanism for survival. The neonatal Lin28⁺Let7^– developmental pathway allows increased generation of Th2-type cells and B1a (B-1 B) cells compared to adult cells and long-term maintenance of these initially generated innate cells. For initial B1a cell growth from the neonatal to adult stage, Th2-type IL-5 production from ILC2s and NKT2 cells is important to increase B1a cells. The Th17 increase is dependent on extracellular bacteria, and increased bacteria leads to lower Th2-type generation. Secreted group IIA-phospholipase A2 (sPLA2-IIA) from the Pla2g2a gene can bind to gram-positive bacteria and degrade bacterial membranes, controlling microbiota in the intestine. BALB/c mice are Pla2g2a⁺, and express high numbers of Th2-type cells and B1a cells. C57BL/6 mice are Pla2g2a-deficient and distinct from the SLAM family, and exhibit fewer NKT2 cells and fewer B1a cells from the neonatal to adult stage. We found that loss of Pla2g2a in the BALB/c background decreased IL-5 from Th2-type ILC2s and NKT2s but increased bacterial-reactive NKT17 cells and MAIT cells, and decreased the number of early-generated B1a cells and MZ B cells and the CD4/CD8 T cell ratio. Low IL-5 by decreased Th2-type cells in Pla2g2a loss led to low early-generated B1a cell growth from the neonatal to adult stage. In anti-thymocyte/Thy-1 autoreactive μκ transgenic (ATAμκ Tg) Pla2g2a⁺ BALB/c background C.B17 mice generated NKT2 cells that continuously control CD1d⁺ B1 B cells through old aging and lost CD1d in B1 B cells generating strong B1 ATA B cell leukemia/lymphoma. Pla2g2a-deficient ATAμκTg C57BL/6 mice suppressed the initial B1a cell increase, with low/negative spontaneous leukemia/lymphoma generation. These data confirmed that the presence of Pla2g2a to control bacteria is important to allow the neonatal to adult stage. Pla2g2a promotes innate Th2-type immunity lymphocytes to increase early generated B1a cells.

Inflammatory Bowel Disease: A Review of Pre-Clinical Murine Models of Human Disease

Crohn’s disease (CD) and ulcerative colitis (UC) are both highly inflammatory diseases of the gastrointestinal tract, collectively known as inflammatory bowel disease (IBD). Although the cause of IBD is still unclear, several experimental IBD murine models have enabled researchers to make great inroads into understanding human IBD pathology. Here, we discuss the current pre-clinical experimental murine models for human IBD, including the chemical-induced trinitrobenzene sulfonic acid (TNBS) model, oxazolone and dextran sulphate sodium (DSS) models, the gene-deficient I-kappa-B kinase gamma (Iκκ-γ) and interleukin(IL)-10 models, and the CD4⁺ T-cell transfer model. We offer a comprehensive review of how these models have been used to dissect the etiopathogenesis of disease, alongside their limitations. Furthermore, the way in which this knowledge has led to the translation of experimental findings into novel clinical therapeutics is also discussed.

Smad4-deficient T cells promote colitis-associated colon cancer via an IFN-γ-dependent suppression of 15-hydroxyprostaglandin dehydrogenase

Immune cells and the cytokines they produce are important mediators of the transition from colitis to colon cancer, but the mechanisms mediating this disease progression are poorly understood. Interferon gamma (IFN-γ) is known to contribute to the pathogenesis of colitis through immune modulatory mechanisms, and through direct effects on endothelial and epithelial homeostasis. Here we explore whether IFN-γ influences tumor progression by expanding the effector memory T cells (T_EM) population and restricting the expression of tumor suppressors in a preclinical model of spontaneous colitis-associated colorectal cancer (CAC). We show that IFN-γ expression is significantly increased both in the T cells and the colonic mucosal epithelia of mice with a T cell-restricted deletion of the TGF-β intermediate, SMAD4 (Smad4^TKO). The increase of IFN-γ expression correlates with the onset of spontaneous CAC in Smad4^TKO mice by 6 months of age. This phenotype is greatly ameliorated by the introduction of a germline deletion of IFN-γ in Smad4^TKO mice (Smad4^TKO/IFN-γ^KO, DKO). DKO mice had a significantly reduced incidence and progression of CAC, and a decrease in the number of mucosal CD4⁺ T_EM cells, when compared to those of Smad4^TKO mice. Similarly, the colon epithelia of DKO mice exhibited a non-oncogenic signature with a decrease in the expression of iNOS and p-STAT1, and a restoration of the tumor suppressor gene, 15-hydroxyprostaglandin dehydrogenase (15-PGDH). In vitro, treatment of human colon cancer cells with IFN-γ decreased the expression of 15-PGDH. Our data suggest that Smad4-deficient T cells promote CAC through mechanisms that include an IFN-γ-dependent suppression of the tumor suppressor 15-PGDH.

TNF-α enhances sensory DRG neuron excitability through modulation of P2X3 receptors in an acute colitis model

Previous studies have demonstrated that acute colonic inflammation leads to an increase in dorsal root ganglia (DRG) neuronal excitability. However, the signaling elements implicated in this hyperexcitability have yet to be fully unraveled. Extracellular adenosine 5’-triphosphate (ATP) is a well-recognized sensory signaling molecule that enhances the nociceptive response after inflammation through activation of P2X3 receptors, which are expressed mainly by peripheral sensory neurons. The aim of this study is to continue investigating how P2X3 affects neuronal hypersensitivity in an acute colitis animal model. To achieve this, DNBS (Dinitrobenzene sulfonic acid; 200 mg/kg) was intrarectally administered to C57BL/6 mice, and inflammation severity was assessed according to the following parameters: weight loss, macroscopic and microscopic scores. Perforated patch clamp technique was used to evaluate neuronal excitability via measuring changes in rheobase and action potential firing in T8-L1 DRG neurons. A-317491, a well-established potent and selective P2X3 receptor antagonist, served to dissect their contribution to recorded responses. Protein expression of P2X3 receptors in DRG was evaluated by western blotting and immunofluorescence. Four days post-DNBS administration, colons were processed for histological analyses of ulceration, crypt morphology, goblet cell density, and immune cell infiltration. DRG neurons from DNBS-treated mice were significantly more excitable compared with controls; these changes correlated with increased P2X3 receptor expression. Furthermore, TNF-α mRNA expression was also significantly higher in inflamed colons compared to controls. Incubation of control DRG neurons with TNF-α resulted in similar cell hyperexcitability as measured in DNBS-derived neurons. The selective P2X3 receptor antagonist, A-317491, blocked the TNF-α-induced effect. These results support the hypothesis that TNF-α enhances colon-innervating DRG neuron excitability via modulation of P2X3 receptor activity.

Lycium barbarum Glycopeptide prevents the development and progression of acute colitis by regulating the composition and diversity of the gut microbiota in mice

In most cases, recurrent chronic colitis is caused by the recurrence of acute colitis after incomplete recovery and re-exposure to irritating factors, and the gut microbiome, which is the largest micro-ecosystem in the human body, plays a crucial role in the development of colitis. Plant polysaccharides have always been reported to have the ability for anti-inflammation, and they are closely related to the gut microbiome. Lycium barbarum Glycopeptide (LbGP), the most potent component obtained by further isolation and purification from Lycium barbarum fruit, has been shown to inhibit inflammation in animal models. However, its therapeutic efficacy in colitis and its mechanism in gut microbiota regulation have not been fully studied. In our study, the dextran sulfate sodium (DSS)-induced mouse model was used to dynamically evaluate the effect of LbGP in the treatment of acute colitis and the mechanism from the perspective of the gut microbiome through the 16S rDNA sequence. The results showed that LbGP treatment significantly alleviated acute colitis and improved the gut microbiome compared with that in the model group. Harmful bacteria, such as Lachnoclostridium spp. and Parabacteroides_distasonis, were inhibited and probiotics, such as Bacteroides_acidifaciens, Lactobacillus spp., Turicibacter spp., and Alistipes spp., were increased by LbGP treatment. Further, a Random Forest analysis with 10-fold cross-validation identified a family named Muribaculaceae representing colitis development and recovery upon LbGP treatment. In conclusion, our study demonstrated the capability of LbGP to prevent the development of acute colitis by regulating the composition and diversity of the gut microbiota and highlighted the dynamic process of gut microbiota with the colitis progression. Further, it provides evidence to develop LbGP as a functional food supplement and future drug acting on intestinal disease.

Characterization of Maladaptive Processes in Acute, Chronic and Remission Phases of Experimental Colitis in C57BL/6 Mice

Inflammatory bowel disease (IBD) is a chronic recurrent inflammatory disease with unknown etiology. Dextran sulfate sodium (DSS) induced colitis is a widely used mouse model in IBD research. DSS colitis involves activation of the submucosal immune system and can be used to study IBD-like disease characteristics in acute, chronic, remission and transition phases. Insight into colon inflammatory parameters is needed to understand potentially irreversible adaptations to the chronification of colitis, determining the baseline and impact of further inflammatory episodes. We performed analyses of non-invasive and invasive colitis parameters in acute, chronic and remission phases of the DSS colitis in C57BL/6 mice. Non-invasive colitis parameters poorly reflected inflammatory aspects of colitis in chronic remission phase. We found invasive inflammatory parameters, positively linked to repeated DSS-episodes, such as specific colon weight, inflamed colon area, spleen weight, absolute cell numbers of CD4+ and CD8+ T cells as well as B cells, blood IFN-γ level, colonic chemokines BLC and MDC as well as the prevalence of Turicibacter species in feces. Moreover, microbial Lactobacillus species decreased with chronification of disease. Our data point out indicative parameters of recurrent gut inflammation in context of DSS colitis.