Insights from advances in research of chemically induced experimental models of human inflammatory bowel disease

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

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

Butyrate Protects Myenteric Neurons Loss in Mice Following Experimental Ulcerative Colitis

The enteric nervous system is affected by inflammatory bowel diseases (IBD). Gut microbiota ferments dietary fibers and produces short-chain fatty acids, such as Butyrate, which bind to G protein-coupled receptors, such as GPR41, and contribute to maintaining intestinal health. This work aimed to study the GPR41 in myenteric neurons and analyze the effect of Butyrate in mice submitted to experimental ulcerative colitis. The 2, 4, 6 trinitrobenzene sulfonic acid (TNBS) was injected intrarectally in C57BL/6 mice (Colitis). Sham group received ethanol (vehicle). One group was treated with 100 mg/kg of Sodium Butyrate (Butyrate), and the other groups received saline. Animals were euthanized 7 days after colitis induction. Analyzes demonstrated colocalization of GPR41 with neurons immunoreactive (-ir) to nNOS and ChAT-ir and absence of colocalization of the GPR41 with GFAP-ir glia. Quantitative results demonstrated losses of nNOS-ir, ChAT-ir, and GPR41-ir neurons in the Colitis group and Butyrate treatment attenuated neuronal loss. The number of GFAP-ir glia increased in the Colitis group, whereas Butyrate reduced the number of these cells. In addition, morphological alterations observed in the Colitis group were attenuated in the Butyrate group. The presence of GPR41 in myenteric neurons was identified, and the treatment with Butyrate attenuated the damage caused by experimental ulcerative colitis.

Study of the roles of caspase-3 and nuclear factor kappa B in myenteric neurons in a P2X7 receptor knockout mouse model of ulcerative colitis

BACKGROUND

The literature indicates that the enteric nervous system is affected in inflammatory bowel diseases (IBDs) and that the P2X7 receptor triggers neuronal death. However, the mechanism by which enteric neurons are lost in IBDs is unknown.

AIM

To study the role of the caspase-3 and nuclear factor kappa B (NF-κB) pathways in myenteric neurons in a P2X7 receptor knockout (KO) mouse model of IBDs.

METHODS

Forty male wild-type (WT) C57BL/6 and P2X7 receptor KO mice were euthanized 24 h or 4 d after colitis induction by 2,4,6-trinitrobenzene sulfonic acid (colitis group). Mice in the sham groups were injected with vehicle. The mice were divided into eight groups (n = 5): The WT sham 24 h and 4 d groups, the WT colitis 24 h and 4 d groups, the KO sham 24 h and 4 d groups, and the KO colitis 24 h and 4 d groups. The disease activity index (DAI) was analyzed, the distal colon was collected for immunohistochemistry analyses, and immunofluorescence was performed to identify neurons immunoreactive (ir) for calretinin, P2X7 receptor, cleaved caspase-3, total caspase-3, phospho-NF-κB, and total NF-κB. We analyzed the number of calretinin-ir and P2X7 receptor-ir neurons per ganglion, the neuronal profile area (µm²), and corrected total cell fluorescence (CTCF).

RESULTS

Cells double labeled for calretinin and P2X7 receptor, cleaved caspase-3, total caspase-3, phospho-NF-κB, or total NF-κB were observed in the WT colitis 24 h and 4 d groups. The number of calretinin-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (2.10 ± 0.13 vs 3.33 ± 0.17, P < 0.001; 2.92 ± 0.12 vs 3.70 ± 0.11, P < 0.05), but was not significantly different between the KO groups. The calretinin-ir neuronal profile area was increased in the WT colitis 24 h group compared to the WT sham 24 h group (312.60 ± 7.85 vs 278.41 ± 6.65, P < 0.05), and the nuclear profile area was decreased in the WT colitis 4 d group compared to the WT sham 4 d group (104.63 ± 2.49 vs 117.41 ± 1.14, P < 0.01). The number of P2X7 receptor-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (19.49 ± 0.35 vs 22.21 ± 0.18, P < 0.001; 20.35 ± 0.14 vs 22.75 ± 0.51, P < 0.001), and no P2X7 receptor-ir neurons were observed in the KO groups. Myenteric neurons showed ultrastructural changes in the WT colitis 24 h and 4 d groups and in the KO colitis 24 h group. The cleaved caspase-3 CTCF was increased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (485949 ± 14140 vs 371371 ± 16426, P < 0.001; 480381 ± 11336 vs 378365 ± 4053, P < 0.001), but was not significantly different between the KO groups. The total caspase-3 CTCF, phospho-NF-κB CTCF, and total NF-κB CTCF were not significantly different among the groups. The DAI was recovered in the KO groups. Furthermore, we demonstrated that the absence of the P2X7 receptor attenuated inflammatory infiltration, tissue damage, collagen deposition, and the decrease in the number of goblet cells in the distal colon.

CONCLUSION

Ulcerative colitis affects myenteric neurons in WT mice but has a weaker effect in P2X7 receptor KO mice, and neuronal death may be associated with P2X7 receptor-mediated caspase-3 activation. The P2X7 receptor can be a therapeutic target for IBDs.

Study of tumor necrosis factor receptor in the inflammatory bowel disease

Ulcerative colitis (UC) and Crohn’s disease (CD) are part of Inflammatory Bowel Diseases (IBD) and have pathophysiological processes such as bowel necrosis and enteric neurons and enteric glial cells. In addition, the main inflammatory mediator is related to the tumor necrosis factor-alpha (TNF-α). TNF-α is a me-diator of the intestinal inflammatory processes, thus being one of the main cytokines involved in the pathogenesis of IBD, however, its levels, when measured, are present in the serum of patients with IBD. In addition, TNF-α plays an important role in promoting inflammation, such as the production of interleukins (IL), for instance IL-1β and IL-6. There are two receptors for TNF as following: The tumor necrosis factor 1 receptor (TNFR1); and the tumor necrosis factor 2 receptor (TNFR2). They are involved in the pathogenesis of IBD and their receptors have been detected in IBD and their expression is correlated with disease activity. The soluble TNF form binds to the TNFR1 receptor with, and its activation results in a signaling cascade effects such as apoptosis, cell proliferation and cytokine secretion. In contrast, the transmembrane TNF form can bind both to TNFR1 and TNFR2. Recent studies have suggested that TNF-α is one of the main pro-inflammatory cytokines involved in the pathogenesis of IBD, since TNF levels are present in the serum of both patients with UC and CD. Intravenous and subcutaneous biologics targeting TNF-α have revolutionized the treatment of IBD, thus becoming the best available agents to induce and maintain IBD remission. The application of antibodies aimed at neutralizing TNF-α in patients with IBD that induce a satisfactory clinical response in up to 60% of patients, and also induced long-term maintenance of disease remission in most patients. It has been suggested that anti-TNF-α agents inactivate the pro-inflammatory cytokine TNF-α by direct neutralization, i.e., resulting in suppression of inflammation. However, anti-TNF-α antibodies perform more complex functions than a simple blockade.

PR1P, a VEGF-stabilizing peptide, reduces injury and inflammation in acute lung injury and ulcerative colitis animal models

Acute Respiratory Distress Syndrome (ARDS) and Ulcerative Colitis (UC) are each characterized by tissue damage and uncontrolled inflammation. Neutrophils and other inflammatory cells play a primary role in disease progression by acutely responding to direct and indirect insults to tissue injury and by promoting inflammation through secretion of inflammatory cytokines and proteases. Vascular Endothelial Growth Factor (VEGF) is a ubiquitous signaling molecule that plays a key role in maintaining and promoting cell and tissue health, and is dysregulated in both ARDS and UC. Recent evidence suggests a role for VEGF in mediating inflammation, however, the molecular mechanism by which this occurs is not well understood. We recently showed that PR1P, a 12-amino acid peptide that binds to and upregulates VEGF, stabilizes VEGF from degradation by inflammatory proteases such as elastase and plasmin thereby limiting the production of VEGF degradation products (fragmented VEGF (fVEGF)). Here we show that fVEGF is a neutrophil chemoattractant in vitro and that PR1P can be used to reduce neutrophil migration in vitro by preventing the production of fVEGF during VEGF proteolysis. In addition, inhaled PR1P reduced neutrophil migration into airways following injury in three separate murine acute lung injury models including from lipopolysaccharide (LPS), bleomycin and acid. Reduced presence of neutrophils in the airways was associated with decreased pro-inflammatory cytokines (including TNF-α, IL-1β, IL-6) and Myeloperoxidase (MPO) in broncho-alveolar lavage fluid (BALF). Finally, PR1P prevented weight loss and tissue injury and reduced plasma levels of key inflammatory cytokines IL-1β and IL-6 in a rat TNBS-induced colitis model. Taken together, our data demonstrate that VEGF and fVEGF may each play separate and pivotal roles in mediating inflammation in ARDS and UC, and that PR1P, by preventing proteolytic degradation of VEGF and the production of fVEGF may represent a novel therapeutic approach to preserve VEGF signaling and inhibit inflammation in acute and chronic inflammatory diseases.

The therapeutic and preventive effects of a canine-origin VB12 -producing Lactobacillus on DSS-induced colitis in mice

Vitamin B12 (VB12 ) plays vital roles as a cofactor in reactions related to biosynthesis and metabolic regulation. Animals with diarrhoea from intestinal inflammation are susceptible to VB12 deficiency due to dysfunctional absorption. No current medications for canine intestinal inflammation can simultaneously act as VB12 supplements. Here we have tested a strain of VB12 -producing Lactobacillus, to investigate its safety in healthy dogs and test for hypothesized therapeutic and preventive effects on murine colitis. Results from enzyme-linked immunosorbent assay, histopathological analysis, and quantitative polymerase chain reaction showed normal physical conditions of healthy dogs given Lactobacillus, and blood biochemical indices showed no significant differences in markers, indicating safety of Lactobacillus to healthy dogs. The microbiota in animals receiving VB12 -producing Lactobacillus probiotic exhibited decreased abundance of Escherichia coli and concomitant increase in Lactobacillus. The probiotic supplement also resulted in downregulation of proinflammatory cytokines in murine colon tissues, reduced myeloperoxidase activity and malondialdehyde level, and significantly increased serum VB12 level and decreased homocysteine in therapeutic and preventive experiments. Moreover, Lactobacillus supplement decreased colonic inflammation and injury, improved gut microbiota, and ameliorated VB12 deficiency as an adjunctive therapy. We conclude this product is potentially beneficial for efficient therapy and prevention of VB12 deficiency form intestinal inflammation in canine clinical practice.

Chlorogenic Acid and Quercetin in a Diet with Fermentable Fiber Influence Multiple Processes Involved in DSS-Induced Ulcerative Colitis but Do Not Reduce Injury

Ulcerative colitis (UC) patients often avoid foods containing fermentable fibers as some can promote symptoms during active disease. Pectin has been identified as a more protective fermentable fiber, but little has been done to determine the interaction between pectin and bioactive compounds present in foods containing that fiber type. Quercetin and chlorogenic acid, two bioactives in stone fruits, may have anti-cancer, anti-oxidant, and anti-inflammatory properties. We hypothesized that quercetin and chlorogenic acid, in the presence of the fermentable fiber pectin, may suppress the expression of pro-inflammatory molecules, alter the luminal environment, and alter colonocyte proliferation, thereby protecting against recurring bouts of UC. Rats (n = 63) received one of three purified diets (control, 0.45% quercetin, 0.05% chlorogenic acid) containing 6% pectin for 3 weeks before exposure to dextran sodium sulfate (DSS, 3% for 48 h, 3x, 2 wk separation, n = 11/diet) in drinking water to initiate UC, or control (no DSS, n = 10/diet) treatments prior to termination at 9 weeks. DSS increased the fecal moisture content (p < 0.05) and SCFA concentrations (acetate, p < 0.05; butyrate, p < 0.05). Quercetin and chlorogenic acid diets maintained SLC5A8 (SCFA transporter) mRNA levels in DSS-treated rats at levels similar to those not exposed to DSS. DSS increased injury (p < 0.0001) and inflammation (p < 0.01) scores, with no differences noted due to diet. Compared to the control diet, chlorogenic acid decreased NF-κB activity in DSS-treated rats (p < 0.05). Quercetin and chlorogenic acid may contribute to the healthy regulation of NF-κB activation (via mRNA expression of IκΒα, Tollip, and IL-1). Quercetin enhanced injury-repair molecule FGF-2 expression (p < 0.01), but neither diet nor DSS treatment altered proliferation. Although quercetin and chlorogenic acid did not protect against overt indicators of injury and inflammation, or fecal SCFA concentrations, compared to the control diet, their influence on the expression of injury repair molecules, pro-inflammatory cytokines, SCFA transport proteins, and NF-κB inhibitory molecules suggests beneficial influences on major pathways involved in DSS-induced UC. Therefore, in healthy individuals or during periods of remission, quercetin and chlorogenic acid may promote a healthier colon, and may suppress some of the signaling involved in inflammation promotion during active disease.

Association between intestinal microbiota and inflammatory bowel disease

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), has emerged as a global disease with high incidence, long duration, devastating clinical symptoms, and low curability (relapsing immune response and barrier function defects). Mounting studies have been performed to investigate its pathogenesis to provide an ever‐expanding arsenal of therapeutic options, while the precise etiology of IBD is not completely understood yet. Recent advances in high‐throughput sequencing methods and animal models have provided new insights into the association between intestinal microbiota and IBD. In general, dysbiosis characterized by an imbalanced microbiota has been widely recognized as a pathology of IBD. However, intestinal microbiota alterations represent the cause or result of IBD process remains unclear. Therefore, more evidences are needed to identify the precise role of intestinal microbiota in the pathogenesis of IBD. Herein, this review aims to outline the current knowledge of commonly used, chemically induced, and infectious mouse models, gut microbiota alteration and how it contributes to IBD, and dysregulated metabolite production links to IBD pathogenesis.

Amelioratory Effect of Resistant Starch on Non-alcoholic Fatty Liver Disease via the Gut-Liver Axis

Non-alcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome with a global prevalence. Impaired gut barrier function caused by an unhealthy diet plays a key role in disrupting the immune-metabolic homeostasis of the gut-liver axis (GLA), leading to NAFLD. Therefore, dietary interventions have been studied as feasible alternative therapeutic approaches to ameliorate NAFLD. Resistant starches (RSs) are prebiotics that reduce systemic inflammation in patients with metabolic syndrome. The present review aimed to elucidate the mechanisms of the GLA in alleviating NAFLD and provide insights into how dietary RSs counteract diet-induced inflammation in the GLA. Emerging evidence suggests that RS intake alters gut microbiota structure, enhances mucosal immune tolerance, and promotes the production of microbial metabolites such as short-chain fatty acids (SCFAs) and secondary bile acids. These metabolites directly stimulate the growth of intestinal epithelial cells and elicit GPR41/GPR43, FXR, and TGR5 signaling cascades to sustain immune-metabolic homeostasis in the GLA. The literature also revealed the dietary-immune-metabolic interplay by which RSs exert their regulatory effect on the immune-metabolic crosstalk of the GLA and the related molecular basis, suggesting that dietary intervention with RSs may be a promising alternative therapeutic strategy against diet-induced dysfunction of the GLA and, ultimately, the risk of developing NAFLD.

The protective effect of safranal against intestinal tissue damage in Drosophila

Drosophila is often exposed to harmful environments, and the intestinal epithelium is the first line of defense against external infection. Intestinal stem cells (ISCs) in the Drosophila midgut play a crucial role in maintaining tissue homeostasis and compensating for cell loss caused by tissue damage. Crocus sativus L. (saffron) can protect against intestinal injury in response to inflammation; however, the specific protective components of saffron and the related mechanisms remain unclear. Safranal is one of the main components of saffron. Here, we used dextran sodium sulfate (DSS) or Erwinia carotovora carotovora 15 (Ecc15) to create an intestinal injury model and explored the protective effect of safranal against tissue damage. Excessive proliferation and differentiation of ISCs in the Drosophila midgut were observed after DSS or Ecc15 feeding; however, these phenotypes were rescued after safranal feeding. In addition, we found that this process occurred through inhibition of the c-Jun N-terminal kinase (JNK), epidermal growth factor receptor (EGFR) and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathways. Furthermore, safranal inhibited the Ecc15- and DSS-induced increases in antimicrobial peptide (AMP) and reactive oxygen species (ROS) levels and intestinal epithelial cell death, thereby protecting gut integrity. In summary, safranal was found to have a significant protective effect and maintain intestinal homeostasis in Drosophila; these findings provide a foundation for the application of safranal in clinical research and the treatment of intestinal injury.

Discovery of a Series of Pyrimidine Carboxamides as Inhibitors of Vanin-1

A diaryl ketone series was identified as vanin-1 inhibitors from a high-throughput screening campaign. While this novel scaffold provided valuable probe 2 that was used to build target confidence, concerns over the ketone moiety led to the replacement of this group. The successful replacement of this moiety was achieved with pyrimidine carboxamides derived from cyclic secondary amines that were extensively characterized using biophysical and crystallographic methods as competitive inhibitors of vanin-1. Through optimization of potency and physicochemical and ADME properties, and guided by co-crystal structures with vanin-1, 3 was identified with a suitable profile for advancement into preclinical development.

Enteric nervous system and inflammatory bowel diseases: Correlated impacts and therapeutic approaches through the P2X7 receptor

The enteric nervous system (ENS) consists of thousands of small ganglia arranged in the submucosal and myenteric plexuses, which can be negatively affected by Crohn's disease and ulcerative colitis - inflammatory bowel diseases (IBDs). IBDs are complex and multifactorial disorders characterized by chronic and recurrent inflammation of the intestine, and the symptoms of IBDs may include abdominal pain, diarrhea, rectal bleeding, and weight loss. The P2X7 receptor has become a promising therapeutic target for IBDs, especially owing to its wide expression and, in the case of other purinergic receptors, in both human and model animal enteric cells. However, little is known about the actual involvement between the activation of the P2X7 receptor and the cascade of subsequent events and how all these activities associated with chemical signals interfere with the functionality of the affected or treated intestine. In this review, an integrated view is provided, correlating the structural organization of the ENS and the effects of IBDs, focusing on cellular constituents and how therapeutic approaches through the P2X7 receptor can assist in both protection from damage and tissue preservation.

Effects of a P2X7 receptor antagonist on myenteric neurons in the distal colon of an experimental rat model of ulcerative colitis

Inflammatory bowel diseases (IBDs) are chronic diseases of the gastrointestinal tract that include ulcerative colitis and Crohn's disease and affect enteric neurons. Research has shown that Brilliant Blue G (BBG), a P2X7 receptor antagonist, restores enteric neurons following ischemia and reperfusion. This study aimed to evaluate the effect of BBG on myenteric neurons of the distal colon in an experimental rat model of ulcerative colitis. Colitis was induced by injection of 2,4,6-trinitrobenzene sulfonic acid (TNBS) into the large intestine. BBG was administered 1 h after colitis induction and for five consecutive days thereafter. Distal colons were collected 24 h or 7 days after TNBS injection. The animals were divided into 24-h and 7-day sham (vehicle injection rather than colitis induction), 24-h colitis, 24-h BBG, 7-day colitis and 7-day BBG groups. The disease activity index (DAI), neuronal density and profile of neuronal nitric oxide synthase (nNOS)-, choline acetyltransferase (ChAT)- and P2X7 receptor-immunoreactive enteric neurons were analyzed, and histological analysis was performed. The results showed recovery of the DAI and histological tissue integrity in the BBG groups compared to those in the colitis groups. In addition, the numbers of neurons positive for nNOS, ChAT and the P2X7 receptor per area were decreased in the colitis groups, and these measures were recovered in the BBG groups. Neuronal size was increased in the colitis groups and restored in the BBG groups. In conclusion, BBG is effective in improving experimental ulcerative colitis, and the P2X7 receptor may be a therapeutic target.

Dapagliflozin, an SGLT2 inhibitor, ameliorates acetic acid-induced colitis in rats by targeting NFκB/AMPK/NLRP3 axis

The development of effective treatment strategies has been hindered by the complex pathogenesis of ulcerative colitis (UC). UC patients treated with current therapeutic approaches experienced either treatment failure or suffered excessive adverse reactions. Overactivity of NLRP3 inflammasome enhances inflammation, resulting in aggravation of colonic damage. We were interested in exploring, for the first time, the potential coloprotective effect of dapagliflozin (DPZ) on acetic acid-induced UC in rats in comparison with 5-ASA. DPZ improved histologic and macroscopic features of colon tissues and prolonged survival of UC rats. DPZ also prevented colon shortening and declined disease activity. Additionally, DPZ lessened colon tissue neutrophil content and improved antioxidant defense machinery. Further, DPZ specifically declined the colonic inflammatory marker IL-6 and upregulated the anti-inflammatory cytokine IL-10. The pyroptosis process is constrained in consequence of the repressed caspase-1 activity and caspase-1-dependent release of the bioactive cytokines IL-1β and IL-18. These protective effects might be attributed to that DPZ on the one hand, prevented the priming step (signal 1) of NLRP3 inflammasome activation as revealed by modulating NFκB/AMPK interplay and on the other hand, inhibited the activation step (signal 2) as indicated by interrupting NLRP3/caspase-1 signaling. Since DPZ was found to be safe and well tolerated by healthy volunteers with no evidence of hypoglycemia, it might show promise in the future management of UC. However, further investigations are warranted to confirm the reversal of injury and that the coloprotective effect is substantial.

6-(methylsulfinyl)hexyl isothiocyanate (6-MITC) from Wasabia japonica alleviates inflammatory bowel disease (IBD) by potential inhibition of glycogen synthase kinase 3 beta (GSK-3β)

Inflammatory bowel disease (IBD) describes a set of disorders involving alterations to gastrointestinal physiology and mucosal immunity. Unravelling its complex pathophysiology is important since many IBD patients are refractory to or suffer adverse side effects from current treatments. Isothiocyanates (ITCs), such as 6-(methylsulfinyl)hexyl ITC (6-MITC) in Wasabia japonica, have potential anti-inflammatory activity. We aimed to elucidate the pathways through which 6-MITC alleviates inflammation by examining its role in the nuclear factor-kappa B (NF-κB) pathway through inhibition of glycogen synthase kinase 3 beta (GSK-3β) using a chemically induced murine model of IBD, cell-based and in silico techniques. The effects of 6-MITC and two NF-κB inhibitors, sulfasalazine (SS), pyrrolidine dithiolcarbamate (PDTC) were investigated on a dextran sulfate sodium (DSS)-induced murine mouse model of acute and chronic colitis using macroscopic measurements and pro-inflammatory markers. The effect of 6-MITC on NF-κB induction was assessed using a murine macrophage cell line. Complexes of GSK-3β-6-MITC and GSK-3β-ATP were generated in silico to elucidate the mechanism of 6-MITC's direct inhibition of GSK-3β. Changes in pro-inflammatory markers, inducible nitric oxide synthase (iNOS) (increased) and interleukin-6 (IL-6) (decreased) demonstrated that iNOS regulation occurred at the translational level. Intraperitoneal (ip) injection of 6-MITC to the colitis-induced mice ameliorated weight loss whereas oral administration had negligible effect. Fecal blood and colon weight/length ratio parameters improved on treatment with 6-MITC and the other NF-κB inhibitors. Levels of NF-κB decreased upon addition of 6-MITC in vitro while structural studies showed 6-MITC acts competitively to inhibit GSK-3β at the ATP binding site. In this study we demonstrated that 6-MITC inhibits NF-κB signaling via GSK-3β inhibition ameliorating fecal blood, colonic alterations and DSS-induced weight loss indirectly indicating reduced intestinal stress. Taken together these results suggest a role for 6-MITC in the treatment of IBD acting to alleviate inflammation through the GSK-3β/NF-κB pathway. Furthermore, the GSK-3β-6-MITC model can be utilized as a basis for development of novel therapeutics targeting GSK-3β for use in other disorders including cancer.

A Review of Selected IBD Biomarkers: From Animal Models to Bedside

Inflammatory bowel disease (IBD) is a dysregulated inflammatory condition induced by multiple factors. The etiology of IBD is largely unknown, and the disease progression and prognosis are variable and unpredictable with uncontrolled disease behavior. Monitoring the status of chronic colitis closely is challenging for physicians, because the assessment of disease activity and severity require invasive methods. Using laboratory biomarkers may provide a useful alternative to invasive methods in the diagnosis and management of IBD. Furthermore, patients with ulcerative colitis or Crohn’s disease are also at risk of developing cancer. Annual colonoscopies can help lower the risk for developing colorectal cancer. However, laboratory biomarkers may also be helpful as non-invasive indicators in predicting treatment responses, improving prognosis, and predicting possible tumors. This review addresses selected laboratory biomarkers (including ANCA, chitinase 3-like 1, S100A12/RAGE, calprotectin, and TNF/TNFR2), which are identified by utilizing two well-accepted animal models of colitis, dextran sodium sulfate-induced and T cell receptor alpha knockout colitis models. In addition to being useful for monitoring disease severity, these biomarkers are associated with therapeutic strategies. The factors may regulate the initiation and perpetuation of inflammatory factors in the gut.

Preventive Effect of Lactobacillus acidophilus XY27 on DSS-Induced Ulcerative Colitis in Mice

Introduction

Lactobacillus acidophilus is widely used as probiotic supplement in functional foods due to its beneficial regulatory effects on host, such as immune regulation, anti-inflammatory, and antioxidant activities.

Aim

This study aimed to determine the preventive effect of Lactobacillus acidophilus XY27 (L. acidophilus XY27) on colitis induced by dextran sodium.

Methods

The mice were randomly divided into five groups. Except for the control group, the other four groups were induced for ulcerative colitis (UC) with dextran sodium sulfate (DSS), and three groups in DSS-groups were treated with L. acidophilus XY27, L. bulgaricus, and salicylazosulfapyridine. The weight change, DAI score, colon length, and length to weight ratio were tested. The oxidation index and the levels of inflammatory cytokines in the serum were measured. Subsequently, the gene expression levels of inflammatory factors in the colon tissue were determined by the Real-Time quantitative polymerase chain reaction (qRT-PCR) method.

Results

The results showed that the mice in the L. acidophilus XY27 group performed better in terms of weight, DAI score, colon length, and length to weight ratio or colonic pathological sections compared with the DSS-induced group. Further, the levels of tumor necrosis factor α (TNF-α), Interleukin-6 (IL-6), Interleukin-12 (IL-12) and Interleukin-1β (IL-1β), malondialdehyde (MDA) content, and myeloperoxidase activity in the serum of UC mice treated with L. acidophilus XY27 significantly decreased, while the levels of Interferon-γ (IFN-γ), Interleukin-10 (IL-10), Catalase (CAT), and total superoxide dismutase (SOD) significantly increased. The gene expression levels of Ets-like transcription factor-1 (EIK-1), IL-12, IL-1β, Cyclooxygenase 2 (COX-2), TNF-α, Escherichia coli, Lipopolysaccharide (LPS), and p100 in the colon significantly decreased while those of tight junction protein 1 (ZO-1), nuclear factor kappa B (NF-kB), p53, and NF-kappa-B inhibitor alpha (IκB-α) increased in the L. acidophilus XY27 group.

Conclusion

The results of the experiment suggested that L. acidophilus XY27 prevented colitis and alleviated symptoms in mice with DSS-induced UC, and also repaired the intestinal barrier function.

Diet Rich in Simple Sugars Promotes Pro-Inflammatory Response via Gut Microbiota Alteration and TLR4 Signaling

Diet is a strong modifier of microbiome and mucosal microenvironment in the gut. Recently, components of western-type diets have been associated with metabolic and immune diseases. Here, we studied how high-sugar diet (HSD) consumption influences gut mucosal barrier and immune response under steady state conditions and in a mouse model of acute colitis. We found that HSD significantly increased gut permeability, spleen weight, and neutrophil levels in spleens of healthy mice. Subsequent dextran sodium sulfate administration led to severe colitis. In colon, HSD significantly promoted neutrophil infiltration and increased the levels of IL-6, IL-1β, and TNF-α. Moreover, HSD-fed mice had significantly higher abundance of pathobionts, such as Escherichia coli and Candida, in fecal samples. Although germ-free mice colonized with microbiota of conventionally reared mice that consumed different diets had equally severe colitis, mice colonized with HSD microbiota showed markedly increased infiltration of neutrophils to the gut. The induction of colitis in Toll-like receptor 4 (TLR4)-deficient HSD-fed mice led to significantly milder colitis than in wild-type mice. In conclusion, our results suggested a significant role of HSD in disruption of barrier integrity and balanced mucosal and systemic immune response. In addition, these processes seemed to be highly influenced by resident potentially pathogenic microbiota or metabolites via the TLR4 signaling pathway.

Prebiotics and Probiotics in Inflammatory Bowel Disease: Where are we now and where are we going?

The incidence, prevalence, and cost of care associated with diagnosis and management of inflammatory bowel disease are on the rise. The role of gut microbiota in the causation of Crohn's disease and ulcerative colitis has not been established yet. Nevertheless, several animal models and human studies point towards the association. Targeting intestinal dysbiosis for remission induction, maintenance, and relapse prevention is an attractive treatment approach with minimal adverse effects. However, the data is still conflicting. The purpose of this article is to provide the most comprehensive and updated review on the utility of prebiotics and probiotics in the management of active Crohn's disease and ulcerative colitis/pouchitis and their role in the remission induction, maintenance, and relapse prevention. A thorough literature review was performed on PubMed, Ovid Medline, and EMBASE using the terms "prebiotics AND ulcerative colitis", "probiotics AND ulcerative colitis", "prebiotics AND Crohn's disease", "probiotics AND Crohn's disease", "probiotics AND acute pouchitis", "probiotics AND chronic pouchitis" and "prebiotics AND pouchitis". Observational studies and clinical trials conducted on humans and published in the English language were included. A total of 71 clinical trials evaluating the utility of prebiotics and probiotics in the management of inflammatory bowel disease were reviewed and the findings were summarized. Most of these studies on probiotics evaluated lactobacillus, De Simone Formulation or Escherichia coli Nissle 1917 and there is some evidence supporting these agents for induction and maintenance of remission in ulcerative colitis and prevention of pouchitis relapse with minimal adverse effects. The efficacy of prebiotics such as fructooligosaccharides and Plantago ovata seeds in ulcerative colitis are inconclusive and the data regarding the utility of prebiotics in pouchitis is limited. The results of the clinical trials for remission induction and maintenance in active Crohn's disease or post-operative relapse with probiotics and prebiotics are inadequate and not very convincing. Prebiotics and probiotics are safe, effective and have great therapeutic potential. However, better designed clinical trials in the multicenter setting with a large sample and long duration of intervention are needed to identify the specific strain or combination of probiotics and prebiotics which will be more beneficial and effective in patients with inflammatory bowel disease.

Composites of yeast glucan particles and curcumin lead to improvement of dextran sulfate sodium-induced acute bowel inflammation in rats

The goal of this work was to assess the usability of yeast glucan particles (GPs) as carriers for curcumin and determine the beneficial effect of a pharmacological composite of curcumin in GPs on dextran sulfate sodium induced colitis in rats. The assessment of the anti-inflammatory effect of particular substances was evaluated on the basis of the calculated disease activity index and by assessment of cytokines and enzymes from the gut tissue - tumor necrosis factor α (TNF-α), transforming growth factor β1, interleukin (IL)-1β, IL-6, IL-10, IL-17, catalase, superoxide dismutase 2, myeloperoxidase (MPO), and matrix metalloproteinase 9. Composites of GPs with incorporated curcumin showed promising results with the capability to lower symptoms of colitis and significantly decrease the production of pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and the activity of MPO, as well. The anti-inflammatory effect of the composites was greater than those of pure GPs or curcumin.

Anti-inflammatory Activity of <i>Etlingera elatior</i> (Jack) R.M. Smith Flower on Gastric Ulceration-induced Wistar Rats

BACKGROUND AND OBJECTIVE

Etlingera elatior (Jack) R.M. Smith rhizome, which has been traditionally used to reduce stomach discomfort, was reported to possess anti-inflammatory activity, however, there is a lack of such a study on the flower.

MATERIALS AND METHODS

To investigate the anti-inflammatory activity of the E. elatior flower extract on gastric ulceration-induced Wistar rats. The Wistar rats were divided into 6 groups. Group 1 was the normal control, group 2 was the negative control (Arabic gum suspension 2%), group 3 was the positive control (quercetin), group 4-6 were treated with E. elatior flower extract dose of 500, 1000 and 2000 mg kg-1 of b.wt., respectively. The rats were conditioned to gastric ulceration. The stomach weight, microscopic and macroscopic evaluation of gastric mucosal damage was examined. Subsequently, the nuclear factor-kappaB-p65 (NF-kappaB-p65) expression in the fundus was Western-blotted by employing β-actin and GAPDH as the loading controls.

RESULTS

Etlingera elatior flower extract dose of 1000 mg kg-1 b.wt., reduces the ulceration index and the infiltration of inflammatory cells. Western blot analysis showed inhibition of NF-kappaB-p65 expression by E. elatior flower extract dose of 1000 mg kg-1 of b.wt.

CONCLUSION

Etlingera elatior flower might possess anti-inflammatory activity by downregulating the expression of NF-kappaB-p65 in the fundus of gastric ulceration-induced Wistar rats.

Galectin-1 reduces the severity of dextran sulfate sodium (DSS)-induced ulcerative colitis by suppressing inflammatory and oxidative stress response

Ulcerative colitis is an inflammatory bowel disease that affects a large number of people around the world. Galectin-1 is a β-galactoside-binding lectin with a broad range of biological activities. The effects of galectin-1 on dextran sulfate sodium (DSS)-induced ulcerative colitis in vivo is not clear. We investigated the effect of galectin-1 on colon morphology, cell proliferation, oxidative stress, antioxidant system, and proinflammatory/antiinflammatory cytokines in a DSS-induced mouse model of ulcerative colitis. Thirty-two C57BL/6 mice were randomly assigned to one of the four groups: control, acute colitis, galectin-1, and DSS+galectin-1. Controls were treated with phosphate-buffered saline (PBS) for seven days. Acute colitis was induced by 3% DSS in drinking water administered orally for five days. Mice in galectin-1 groups were treated with 1 mg/kg recombinant human galectin-1 in PBS for seven consecutive days. Oral DSS administration resulted in acute colitis by causing histopathological changes; an increase in disease activity index (DAI), lipid peroxidation (malondialdehyde [MDA]), myeloperoxidase (MPO), and tumor necrosis factor (TNF)-α levels; a decrease in body weight, colon length, cell proliferation index, catalase, glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities, and GSH and interleukin (IL)-10 levels. The treatment with galectin-1 attenuated DSS-induced acute colitis by reducing DAI, MDA, MPO, and TNF-α levels and by increasing body weight, colon length, cell proliferation, antioxidant enzyme activity, GSH, and IL-10 levels. These findings suggest that galectin-1 has proliferative, antioxidant, antiinflammatory, and cytoprotective effects against DSS-induced ulcerative colitis in mice. Due to its antiinflammatory and antioxidant activity galectin-1 may be effective in preventing and treating ulcerative colitis.

P2X7 receptor antagonist recovers ileum myenteric neurons after experimental ulcerative colitis

BACKGROUND

The P2X7 receptor is expressed by enteric neurons and enteric glial cells. Studies have demonstrated that administration of a P2X7 receptor antagonist, brilliant blue G (BBG), prevents neuronal loss.

AIM

To report the effects of BBG in ileum enteric neurons immunoreactive (ir) following experimental ulcerative colitis in Rattus norvegicus albinus.

METHODS

2,4,6-trinitrobenzene sulfonic acid (TNBS group, n = 5) was injected into the distal colon. BBG (50 mg/kg, BBG group, n = 5) or vehicle (sham group, n = 5) was given subcutaneously 1 h after TNBS. The animals were euthanized after 24 h, and the ileum was removed. Immunohistochemistry was performed on the myenteric plexus to evaluate immunoreactivity for P2X7 receptor, neuronal nitric oxide synthase (nNOS), choline acetyltransferase (ChAT), HuC/D and glial fibrillary acidic protein.

RESULTS

The numbers of nNOS-, ChAT-, HuC/D-ir neurons and glial fibrillary acidic protein-ir glial cells were decreased in the TNBS group and recovered in the BBG group. The neuronal profile area (μm²) demonstrated that nNOS-ir neurons decreased in the TNBS group and recovered in the BBG group. There were no differences in the profile areas of ChAT- and HuC/D-ir neurons.

CONCLUSION

Our data conclude that ileum myenteric neurons and glial cells were affected by ulcerative colitis and that treatment with BBG had a neuroprotective effect. Thus, these results demonstrate that the P2X7 receptor may be an important target in therapeutic strategies.

Dietary Red Meat Adversely Affects Disease Severity in a Pig Model of DSS-Induced Colitis Despite Reduction in Colonic Pro-Inflammatory Gene Expression

Diet plays a substantial role in the pathogenesis and management of ulcerative colitis (UC), and epidemiologic studies indicate an association between red meat intake and increased risk of UC development. Therefore, we evaluated the effect of a red meat diet on dextran sulfate sodium (DSS)-induced colitis in pigs. Weaned pigs (42 days old) were fed either a control diet or a diet substituted with 15% minced, cooked and dried beef from experimental day 0 to 14. From day 14 to 18, half of the pigs on each diet received a daily oral dose of DSS. Dietary red meat aggravated the severity of colitis based on clinical signs of disease (negative performance score) and histopathological parameters in the colon such as erosion/ulceration and the overall inflammation score but no negative effects were observed on systemic health or small intestinal permeability. Importantly, dietary meat also caused a potential beneficial reduction in the colonic expression of the pro-inflammatory cytokines IL-17A and IL-6, the pro-inflammatory enzyme PTGS2 and in the chemokine IL-8. The present study emphasizes the potential of diet to modulate mucosal inflammation and that a red meat diet might be a risk factor for the development of inflammatory bowel disease.

Optical coherent tomography to evaluate the degree of inflammation in a mouse model of colitis

Background

There is an urgent need to develop a noninvasive imaging technique for the diagnosis of early inflammatory lesions or early and real-time microscopic assessment before selecting the most representative biopsy sites.

Methods

In this study, a dextran sulfate sodium colitis model was developed, and intestinal histological damage scores measured the degree of inflammation in colitis. According to these scores, 6 parameters were designed for hematoxylin and eosin (HE) sections based on morphological changes, and 2 parameters were designed for optical coherence tomography (OCT) images to measure submucosal edema by morphological changes to evaluate inflammation degrees in the colon. Spearman's rank correlation method was used to compare the correlation between the submucosal morphological changes and the different degrees of inflammation. One-way analysis of variance (ANOVA) was used for comparisons among groups, while receiver operating characteristic (ROC) curves of the indicators in HE sections and OCT images were plotted.

Results

In HE sections, angle of mucosal folds (r=0.853, P<0.01), length of basilar parts (r=0.915, P<0.01), submucosal area (r=0.819, P<0.01), and height between submucosal and muscular layers (r=0.451, P=0.001) were correlated with the degree of inflammation in colitis. In OCT images, length of basilar parts (r=0.800, P<0.01) and height of submucosa + thickness of muscularis (r=0.648, P=0.001) were correlated with the degree of inflammation and aided the measurement of inflammation in the colon.

Conclusions

Parameters based on morphological changes in OCT images and HE sections were significant indexes for evaluating the degree of inflammation in colitis. OCT images have advantages for future clinical applications in situ, including noninvasiveness and real-time imaging.

Recent updates on the basic mechanisms and pathogenesis of inflammatory bowel diseases in experimental animal models

The specific pathogenesis underlining inflammatory bowel disease (IBD) is very complicated, and it is further more difficult to clearly explain the pathophysiology of 2 major forms of IBD, Crohn’s disease (CD) and ulcerative colitis (UC), and both disorders affect individuals throughout life. Despite every extensive effort, the interplay among genetic factors, immunological factors, environmental factors and intestinal microbes is still completely unrevealed. Animal models are indispensable to find out mechanistic details that will facilitate better preclinical setting to target specific components involved in the pathogenesis of IBD. Based on many recent reports, dysbiosis of the commensal microbiota is implicated in the pathogenesis of several diseases, not only IBD but also colon cancer, obesity, psoriasis as well as allergic disorders, in both human and animal models. Advanced technologies including cell-specific and inducible knockout systems, which are recently employed to mouse IBD models, have further enhanced the ability of developing new therapeutic strategies for IBD. Furthermore, data from these mouse models highlight the critical involvement of dysregulated immune responses and impaired colonic epithelial defense system in the pathogenesis of IBD. In this review, we will explain from the history of animal models of IBD to the recent reports of the latest compounds, therapeutic strategies, and approaches tested on IBD animal models.

Mouse models of colorectal cancer: Past, present and future perspectives

Colorectal cancer (CRC) is the third most common diagnosed malignancy among both sexes in the United States as well as in the European Union. While the incidence and mortality rates in western, high developed countries are declining, reflecting the success of screening programs and improved treatment regimen, a rise of the overall global CRC burden can be observed due to lifestyle changes paralleling an increasing human development index. Despite a growing insight into the biology of CRC and many therapeutic improvements in the recent decades, preclinical in vivo models are still indispensable for the development of new treatment approaches. Since the development of carcinogen-induced rodent models for CRC more than 80 years ago, a plethora of animal models has been established to study colon cancer biology. Despite tenuous invasiveness and metastatic behavior, these models are useful for chemoprevention studies and to evaluate colitis-related carcinogenesis. Genetically engineered mouse models (GEMM) mirror the pathogenesis of sporadic as well as inherited CRC depending on the specific molecular pathways activated or inhibited. Although the vast majority of CRC GEMM lack invasiveness, metastasis and tumor heterogeneity, they still have proven useful for examination of the tumor microenvironment as well as systemic immune responses; thus, supporting development of new therapeutic avenues. Induction of metastatic disease by orthotopic injection of CRC cell lines is possible, but the so generated models lack genetic diversity and the number of suited cell lines is very limited. Patient-derived xenografts, in contrast, maintain the pathological and molecular characteristics of the individual patient’s CRC after subcutaneous implantation into immunodeficient mice and are therefore most reliable for preclinical drug development – even in comparison to GEMM or cell line-based analyses. However, subcutaneous patient-derived xenograft models are less suitable for studying most aspects of the tumor microenvironment and anti-tumoral immune responses. The authors review the distinct mouse models of CRC with an emphasis on their clinical relevance and shed light on the latest developments in the field of preclinical CRC models.

Unexpected effect of probiotics by Lactococcus lactis subsp. lactis against colitis induced by dextran sulfate sodium in mice

Ulcerative colitis (UC) is a representative intestinal chronic inflammatory disease whose incidence is rapidly increasing worldwide. It was previously shown that some specific probiotics help to guard against UC. In this study, we analyzed the effect of Lactococcus lactis subsp. lactis JCM5805 (L. lactis), which has been put to practical use as a probiotic, on the pathogenesis of UC using a dextran sulfate sodium-induced colitis mouse model. Survival rate, length, and histopathological parameters of the colon were elucidated. Further, the concentrations of inflammatory cytokines in serum were measured. As a result, the oral administration of high-dose L. lactis showed significant decreases in survival rate and colon length. Histopathological analysis showed that a bleeding appearance was observed in the L. lactis group, and the histology scores in the L. lactis group were significantly higher than those in the normal saline group. Furthermore, the levels of interferon gamma, tumor necrosis factor alpha, and interleukin-6 were significantly elevated in the L. lactis group. These results support that high-dose administration of L. lactis deteriorates intestinal inflammation and suggest that the careful selection of probiotics strains and administration dose is important for improving colitis including UC.

Consumption of a baked corn and bean snack reduced chronic colitis inflammation in CD-1 mice via downregulation of IL-1 receptor, TLR, and TNF-α associated pathways

Ulcerative colitis (UC) is a condition that has been rising in the number of cases around the world. Food products made from natural ingredients such as corn and common bean might serve as alternatives for the treatment of UC. This study aimed to assess the anti-inflammatory effect of the consumption of a baked corn and bean snack (CBS) in an in vivo model of UC using 2% dextran sodium sulfate (DSS) as inductor of colitis. CD-1 mice (45, n = 9/group) were randomly separated into 5 groups, treated for 6-weeks as follows: G1 (basal diet, BD), G2 (2% DSS), G3 (20 g CBS/body weight BW/day + BD), G4 (40 g CBS/BW/day + BD) and G5 (60 g CBS/BW/day + BD). BW, Disease Activity Index (DAI), and feces were collected throughout the treatment. After euthanasia, organs (spleen, liver, and colon) were excised and weighed. Feces were analyzed for β-glucuronidase (β-GLUC) activity and gas-chromatography. The colons were analyzed for histopathology, myeloperoxidase (MPO) activity, and gene analysis. At the end of treatments, among the DSS-induced groups, G3 exhibited the lowest BW losses (11.5%), MPO activity (10.4%) and β-GLUC (8.6%). G4 presented the lowest DAI (0.88), relative spleen weight, and histological inflammation score (p < 0.05). Compared to G2, CBS consumption significantly (p < 0.05) reduced serum TNF-α, IL-10, and MCP-1 levels. The fecal metabolome analysis ranked 9-decenoic acid, decane, and butyric acid as the main contributors of pathways associated with the β-oxidation of fatty acids. G4 showed the highest fecal/cecal contents of short-chain fatty acids among all the DSS-induced groups. For the gene expression, G4 was clustered with G1, showing a differential inhibition of the pro-inflammatory genes Il1r1, Il1a, Tlr4, Tlr2, and Tnfrsf1b. In conclusion, CBS consumption decreased the inflammatory state and reduced the expression of the IL-1 receptor, TLR, and TNF-α-associated pathways in DSS-induced UC in CD-1 mice.

A Review of the Effects of Pain and Analgesia on Immune System Function and Inflammation: Relevance for Preclinical Studies

One of the most significant challenges facing investigators, laboratory animal veterinarians, and IACUCs, is how to balance appropriate analgesic use, animal welfare, and analgesic impact on experimental results. This is particularly true for in vivo studies on immune system function and inflammatory disease. Often times the effects of analgesic drugs on a particular immune function or model are incomplete or don't exist. Further complicating the picture is evidence of the very tight integration and bidirectional functionality between the immune system and branches of the nervous system involved in nociception and pain. These relationships have advanced the concept of understanding pain as a protective neuroimmune function and recognizing pathologic pain as a neuroimmune disease. This review strives to summarize extant literature on the effects of pain and analgesia on immune system function and inflammation in the context of preclinical in vivo studies. The authors hope this work will help to guide selection of analgesics for preclinical studies of inflammatory disease and immune system function.

Comparative Analysis of Midgut Regeneration Capacity and Resistance to Oral Infection in Three Disease-Vector Mosquitoes

Mosquitoes acquire the pathogens they transmit through ingestion, and the insects' gut constitutes the first line of defense against invading pathogens. Indeed the gut epithelium acts as a physical barrier, activates local antimicrobial peptides production and triggers the systemic immune response. Consequently, gut epithelium is constantly confronted to stress and often suffers cellular damage. We have previously shown that regenerative cells are present in the guts of adult Aedes albopictus, and that chemical damage or bacterial infection leads to the proliferation of these regenerative cells in the midgut. In this study, we extended the analysis of gut cells response to stress to two other important disease vector mosquitoes: Culex pipiens and Anopheles gambiae. We fed mosquitoes on sucrose solutions or on sucrose supplemented with pathogenic bacteria or with damage-inducing chemicals. We also assayed the survival of mosquitoes following the ingestion of pathogenic bacteria. We found that in adult C. pipiens, dividing cells exist in the digestive tract and that these cells proliferate in the midgut after bacterial or chemical damage, similarly to what we previously observed in A. albopictus. In sharp contrast, we did not detect any mitotic cell in the midguts of A. gambiae mosquitoes, neither in normal situation nor after the induction of gut damage. In agreement with this observation, A. gambiae mosquitoes were more sensitive to oral bacterial infections compared to A. albopictus and C. pipiens. This work provides evidence that major differences in gut physiological responses exist between different mosquitoes. The presence of regenerative cells in the mosquito guts and their ability to multiply after gut damage affect the mosquito survival to oral infections, and is also likely to affect its vectorial capacity.

Vanin 1: Its Physiological Function and Role in Diseases

The enzyme vascular non-inflammatory molecule-1 (vanin 1) is highly expressed at gene and protein level in many organs, such as the liver, intestine, and kidney. Its major function is related to its pantetheinase activity; vanin 1 breaks down pantetheine in cysteamine and pantothenic acid, a precursor of coenzyme A. Indeed, its physiological role seems strictly related to coenzyme A metabolism, lipid metabolism, and energy production. In recent years, many studies have elucidated the role of vanin 1 under physiological conditions in relation to oxidative stress and inflammation. Vanin’s enzymatic activity was found to be of key importance in certain diseases, either for its protective effect or as a sensitizer, depending on the diseased organ. In this review, we discuss the role of vanin 1 in the liver, kidney, intestine, and lung under physiological as well as pathophysiological conditions. Thus, we provide a more complete understanding and overview of its complex function and contribution to some specific pathologies.

Effects of dietary exposure to chlorpyrifos on immune cell populations and inflammatory responses in mice with dextran sulfate sodium-induced colitis

This study investigated the effects of chlorpyrifos (CPF) on immune-cell populations and intestinal inflammation using a mouse model of inflammatory bowel disease induced by dextran sulfate sodium (DSS). C57BL/6 mice were randomly assigned to five groups with one normal control (NC) and four DSS-treated groups. Mice in the NC group were given distilled water, whereas the DSS-treated groups received distilled water containing 3% DSS for 6 days to induce colitis. The NC and disease control (DC) groups were fed a control semipurified diet, while the remaining groups were exposed to CPF in the AIN-93 diet at doses of 1, 2.5, or 5 mg/kg/day throughout the study. Results showed that dietary exposure to CPF in colitic mice significantly increased circulating classical monocytes and upregulated gene expressions of chemokines in the colon compared to the NC group. Meanwhile, CPF exposure groups had lower plasma cholinesterase activities and higher percentages of circulating neutrophils than those of the DC group. A shorten length, tissue edema, and lipid peroxidation of the colon were also observed in all CPF-exposed mice. These findings suggest that dietary exposure to CPF affected immune-cell populations and inflammatory responses, which led to more severe tissue injury in mice with DSS-induced colitis.

Role of TRPV1 and TRPA1 Ion Channels in Inflammatory Bowel Diseases: Potential Therapeutic Targets?

Inflammatory bowel diseases (IBD) have long been recognized to be accompanied by pain resulting in high morbidity. Transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) ion channels located predominantly on the capsaicin-sensitive sensory neurons play a complex role in hyperalgesia and neurogenic inflammation. This review provides an overview of their expression and role in intestinal inflammation, in particular colitis, that appears to be virtually inconsistent based on the thorough investigations of the last twenty years. However, preclinical results with pharmacological interventions, as well as scarcely available human studies, more convincingly point out the potential therapeutic value of TRPV1 and TRPA1 antagonists in colitis and visceral hypersensitivity providing future therapeutical perspectives through a complex, unique mechanism of action for drug development in IBD.

The conserved protective cyclic AMP-phosphodiesterase function PDE4B is expressed in the adenoma and adjacent normal colonic epithelium of mammals and silenced in colorectal cancer

Conservation over three mammalian genera-the mouse, rat, and human-has been found for a subset of the transcripts whose level differs between the adenoma and normal epithelium of the colon. Pde4b is one of the triply conserved transcripts whose level is enhanced both in the colonic adenoma and in the normal colonic epithelium, especially adjacent to adenomas. It encodes the phosphodiesterase PDE4B, specific for cAMP. Loss of PDE4B function in the ApcMin/+ mouse leads to a significant increase in the number of colonic adenomas. Similarly, Pde4b-deficient ApcMin/+ mice are hypersensitive to treatment by the inflammatory agent DSS, becoming moribund soon after treatment. These observations imply that the PDE4B function protects against ApcMin-induced adenomagenesis and inflammatory lethality. The paradoxical enhancement of the Pde4b transcript in the adenoma versus this inferred protective function of PDE4B can be rationalized by a feedback model in which PDE4B is first activated by early oncogenic stress involving cAMP and then, as reported for frank human colon cancer, inactivated by epigenetic silencing.

Intake of Protein Hydrolysates and Phenolic Fractions Isolated from Flaxseed Ameliorates TNBS-Induced Colitis

SCOPE

In the attempt to develop new therapeutic treatments for colitis, fractions containing phenolic compound isolate (Phi) and phenolic reduced-flaxseed protein hydrolysate (phr-FPH) from flaxseed are evaluated for their effects on the in vitro production of pro-inflammatory mediators and on the course of experimental colitis.

METHODS AND RESULTS

The anti-inflammatory effects of Phi and phr-FPH from flaxseeds are studied in RAW264.7 cells and in trinitrobenzene sulphonic acid (TNBS) colitis model. It is observed that the incubation with Phi or phr-FPH result in lower levels of tumor necrosis factor α and nitric oxide in macrophages stimulated with bacterial lipopolysaccharide + interferon-γ. Prophylactic and therapeutic treatments with Phi and phr-FPH, respectively, greatly contribute to the prevention of weight loss and colon inflammation in colitic BALB/c mice. T cell proliferation, expansion of TH1 and TH17 cells, and pro-inflammatory cytokines are lower, whereas Treg cells are higher in spleen cell cultures from Phi-treated mice. In addition, therapeutic phr-FPH treatment is able to reduce the expansion of TH17 in splenic cell cultures.

CONCLUSION

The consumption of phenolic and protein compounds extracted from flaxseeds has a protective effect on TNBS-induced colitis, and may be useful in the control of other inflammatory disorders.

Treatment with Obestatin-A Ghrelin Gene-Encoded Peptide-Reduces the Severity of Experimental Colitis Evoked by Trinitrobenzene Sulfonic Acid

Obestatin is a 23-amino acid peptide derived from proghrelin, a common prohormone for ghrelin and obestatin. Previous studies showed that obestatin exhibited some protective and therapeutic effects in the gut. The aim of our presented study was to examine the effect of treatment with obestatin on trinitrobenzene sulfonic acid (TNBS)-induced colitis. In rats anesthetized with ketamine, colitis was induced through intrarectal administration of 25 mg of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Obestatin was administered intraperitoneally at doses of 4, 8, or 16 nmol/kg, twice per day for four consecutive days. The first dose of obestatin was given one day before the induction of colitis, and the last one was given two days after administration of TNBS. Fourteen days after the induction of colitis, rats were anesthetized again with ketamine, and the severity of colitis was determined. The administration of obestatin had no effect on the parameters tested in rats without the induction of colitis. In rats with colitis, administration of obestatin at doses of 8 or 16 nmol/kg reduced the area of colonic damage, and improved mucosal blood flow in the colon. These effects were accompanied by a reduction in the colitis-evoked increase in the level of blood leukocytes, and mucosal concentration of pro-inflammatory interleukin-1β. Moreover, obestatin administered at doses of 8 or 16 nmol/kg reduced histological signs of colonic damage. The administration of obestatin at a dose of 4 nmol/kg failed to significantly affect the parameters tested. Overall, treatment with obestatin reduced the severity of TNBS-induced colitis in rats. This effect was associated with an improvement in mucosal blood flow in the colon, and a decrease in local and systemic inflammatory processes.

Oral administration of curcumin attenuates visceral hyperalgesia through inhibiting phosphorylation of TRPV1 in rat model of ulcerative colitis

Background Curcumin has been reported to have anti-inflammatory and anti-nociceptive effects. The present study was designed to explore the potential therapeutic effects of curcumin on visceral hyperalgesia and inflammation in a rat model of ulcerative colitis. We observed the effects of orally administered curcumin on the disease activity index, histological change in colon, colorectal distension-induced abdominal withdrawal reflex, the expression of transient receptor potential vanilloid 1 (TRPV1) and phosphorylated TRPV1 in dextran sulfate sodium-induced colitis rats. In addition, a HEK293 cell line stably expressing human TRPV1 (hTRPV1) was used to examine the effects of curcumin on the change in membrane expression of TRPV1 induced by phorbol myristate acetate (a protein kinase C activator). Results Repeated oral administration of curcumin inhibited the increase in abdominal withdrawal reflex score induced by dextran sulfate sodium without affecting dextran sulfate sodium-induced histological change of colon and the disease activity index. A significant increase in colonic expression of TRPV1 and pTRPV1 was observed in dextran sulfate sodium-treated rats and this was reversed by oral administration of curcumin. TRPV1 expression in L6-S1 dorsal root ganglion was increased in the small- to medium-sized isolectin B4-positive non-peptidergic and calcitonin gene-related peptide-positive peptidergic neurons in dextran sulfate sodium-treated rats and oral administration of curcumin mitigated such changes. In the HEK293 cell line stably expressing hTRPV1, curcumin (1, 3 µm) inhibited phorbol myristate acetate-induced upregulation of membrane TRPV1. Conclusion Oral administration of curcumin alleviates visceral hyperalgesia in dextran sulfate sodium-induced colitis rats. The anti-hyperalgesic effect is partially through downregulating the colonic expression and phosphorylation of TRPV1 on the afferent fibers projected from peptidergic and non-peptidergic nociceptive neurons of dorsal root ganglion.

Fluorescence-mediated Tomography for the Detection and Quantification of Macrophage-related Murine Intestinal Inflammation

Murine models of disease are indispensable to scientific research. However, many diagnostic tools such as endoscopy or tomographic imaging are not routinely employed in animal models. Conventional experimental readouts often rely on post mortem and ex vivo analyses, which prevent intra-individual follow-up examinations and increase the number of study animals needed. Fluorescence-mediated tomography enables the non-invasive, repetitive, quantitative, three-dimensional assessment of fluorescent probes. It is highly sensitive and permits the use of molecular makers, which allows for the specific detection and characterization of distinct molecular targets. In particular, targeted probes represent an innovative tool for analyzing gene activation and protein expression in inflammation, autoimmune disease, infection, vascular disease, cell migration, tumorigenesis, etc. In this article, we provide step-by-step instructions on this sophisticated imaging technology for the in vivo detection and characterization of inflammation (i.e., F4/80-positive macrophage infiltration) in a widely used murine model of intestinal inflammation. This technique might also be used in other research areas, such as immune cell or stem cell tracking.

Exogenous murine antimicrobial peptide CRAMP significantly exacerbates Ovalbumin-induced airway inflammation but ameliorates oxazolone-induced intestinal colitis in BALB/c mice

Cathelicidin has been reported to be multifunctional. The current study aimed to investigate the influences of exogenous cathelicidin-related antimicrobial peptide (CRAMP) on inflammatory responses in different disease models. In OVA-induced allergic airway inflammation, CRAMP significantly enhanced the infiltration of inflammatory cells and accumulation of proinflammatory Th2 cytokine IL-13 and IL-33 in bronchial alveolar lavage fluid (BALF), exacerbated lung tissue inflammation and airway goblet cell hyperplasia, and elevated OVA-specific IgE level in serum. In oxazolone-induced intestinal colitis, the expression levels of CRAMP and its receptor FPR2 significantly increased in comparison with those of TNBS-induced mice, vesicle and normal controls. Exogenous CRAMP significantly prevented the development of ulcerative colitis, evidenced by improved body weight regain, decreased colons weight/length ratio, elevated epithelial integrity, and ameliorated colon tissue inflammation. In addition, pro-inflammatory cytokines TNF-α, IL-1β, IL-4 and IL-13, as well as chemokines CXCL2 and CXCL5 for neutrophils recruitment were significantly decreased in CRAMP-treated mice, and epithelial repair-related factors MUC2 and Claudin1 were increased, determined by real time-PCR and ELISAs. The results indicated that although CRAMP has pro-inflammatory effects in airway, local application of exogenous CRAMP might be a potential approach for the treatment of ulcerative colitis.

Effect of roxithromycin on mucosal damage, oxidative stress and pro-inflammatory markers in experimental model of colitis

OBJECTIVE AND DESIGN

Roxithromycin, a macrolide antibiotic, exhibits anti-inflammatory property. The present study was designed to evaluate its protective effect in a rat model of colitis.

METHODS

The anti-inflammatory property of roxithromycin was first validated in rat paw edema model at 5 and 20 mg/kg doses where it produced 19 and 51% inhibition of paw swelling induced by carrageenan. The efficacy of roxithromycin was evaluated at these doses in a rat model where colitis was induced by intra-colonic instillation of acetic acid. Rats were divided into six groups viz. normal control, experimental control and drug-treated groups: roxithromycin 5 and 20 mg/kg, diclofenac 10 mg/kg and mesalazine 300 mg/kg. All drugs were given orally 1 h before induction of colitis. The macro and microscopic changes, mean ulcer score, mucus content and markers of oxidative stress and inflammation were evaluated in all the groups after 24 h.

RESULTS

Pretreatment with roxithromycin markedly decreased hyperemia, ulceration, edema and restored histological architecture. The protection afforded by roxithromycin was substantiated by dose-dependent increase in mucus content, normalization of markers of oxidative stress (GSH and TBARS) and levels of TNF-α, PGE₂ and nitrite along with marked decrease in expression of NFκB (p65), IL-1β and COX-2. The protective effect of roxithromycin was found to be comparable to mesalazine while diclofenac was found ineffective.

CONCLUSION

Our study demonstrates that roxithromycin ameliorates experimental colitis by maintaining redox homeostasis, preserving mucosal integrity and downregulating NFκB-mediated pro-inflammatory signaling and suggests that it has a therapeutic potential in inflammatory conditions of the colon.

Dextran sodium sulfate colitis murine model: An indispensable tool for advancing our understanding of inflammatory bowel diseases pathogenesis

Inflammatory bowel diseases (IBD), including Crohn’s disease and ulcerative colitis, are complex diseases that result from the chronic dysregulated immune response in the gastrointestinal tract. The exact etiology is not fully understood, but it is accepted that it occurs when an inappropriate aggressive inflammatory response in a genetically susceptible host due to inciting environmental factors occurs. To investigate the pathogenesis and etiology of human IBD, various animal models of IBD have been developed that provided indispensable insights into the histopathological and morphological changes as well as factors associated with the pathogenesis of IBD and evaluation of therapeutic options in the last few decades. The most widely used experimental model employs dextran sodium sulfate (DSS) to induce epithelial damage. The DSS colitis model in IBD research has advantages over other various chemically induced experimental models due to its rapidity, simplicity, reproducibility and controllability. In this manuscript, we review the newer publicized advances of research in murine colitis models that focus upon the disruption of the barrier function of the intestine, effects of mucin on the development of colitis, alterations found in microbial balance and resultant changes in the metabolome specifically in the DSS colitis murine model and its relation to the pathogenesis of IBD.

Brassica-Derived Plant Bioactives as Modulators of Chemopreventive and Inflammatory Signaling Pathways

A high consumption of vegetables belonging to the Brassicaceae family has been related to a lower incidence of chronic diseases including different kinds of cancer. These beneficial effects of, e.g., broccoli, cabbage or rocket (arugula) intake have been mainly dedicated to the sulfur-containing glucosinolates (GLSs)-secondary plant compounds nearly exclusively present in Brassicaceae-and in particular to their bioactive breakdown products including isothiocyanates (ITCs). Overall, the current literature indicate that selected Brassica-derived ITCs exhibit health-promoting effects in vitro, as well as in laboratory mice in vivo. Some studies suggest anti-carcinogenic and anti-inflammatory properties for ITCs which may be communicated through an activation of the redox-sensitive transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) that controls the expression of antioxidant and phase II enzymes. Furthermore, it has been shown that ITCs are able to significantly ameliorate a severe inflammatory phenotype in colitic mice in vivo. As there are studies available suggesting an epigenetic mode of action for Brassica-derived phytochemicals, the conduction of further studies would be recommendable to investigate if the beneficial effects of these compounds also persist during an irregular consumption pattern.

The PSMP-CCR2 interactions trigger monocyte/macrophage-dependent colitis

Monocytes/macrophages have been found to be an important component of colitis. However, the key chemokine that initiates the CCR2⁺ monocytes migration from circulation to colitis tissue remains to be undiscovered. PC3-secreted microprotein (PSMP) is a novel chemokine whose receptor is CCR2. The physiological and pathological functions of PSMP have not yet been reported. In this study, PSMP was found to be expressed in colitis and colonic tumor tissues from patients and significantly up-regulated in mouse DSS-induced colitis tissues. PSMP overexpression in the colon aggravated the DSS-induced colitis and the anti-PSMP neutralizing antibody mollified the colitis by reducing macrophage infiltration and inhibiting the expression of IL-6, TNF-α and CCL2. Furthermore, we demonstrated that lipopolysaccharide and muramyl dipeptide induced PSMP expression in the colonic epithelial cells. PSMP was up-regulated in the initial stage prior to IL-6, TNF-α and CCL2 up-regulated expression in DSS colitis and promoted the M1 macrophages to produce CCL2. PSMP chemo-attracted Ly6C^hi monocytes in a CCR2 dependent manner via in situ chemotaxis and adoptive transfer assays. Our data identify PSMP as a key molecule in ulcerative colitis, which provides a novel mechanism of monocyte/macrophage migration that affects gut innate immunity and makes PSMP a potential target for controlling colitis.

Submucosal neurons and enteric glial cells expressing the P2X7 receptor in rat experimental colitis

The aim of this study was to evaluate the effect of ulcerative colitis on the submucosal neurons and glial cells of the submucosal ganglia of rats. 2,4,6-Trinitrobenzene sulfonic acid (TNBS; colitis group) was administered in the colon to induce ulcerative colitis, and distal colons were collected after 24h. The colitis rats were compared with those in the sham and control groups. Double labelling of the P2X7 receptor with calbindin (marker for intrinsic primary afferent neurons, IPANs, submucosal plexus), calretinin (marker for secretory and vasodilator neurons of the submucosal plexus), HuC/D and S100β was performed in the submucosal plexus. The density (neurons per area) of submucosal neurons positive for the P2X7 receptor, calbindin, calretinin and HuC/D decreased by 21%, 34%, 8.2% and 28%, respectively, in the treated group. In addition, the density of enteric glial cells in the submucosal plexus decreased by 33%. The profile areas of calbindin-immunoreactive neurons decreased by 25%. Histological analysis revealed increased lamina propria and decreased collagen in the colitis group. This study demonstrated that ulcerative colitis affected secretory and vasodilatory neurons, IPANs and enteric glia of the submucosal plexus expressing the P2X7 receptor.