Sodium arsenite reduces severity of dextran sulfate sodium-induced ulcerative colitis in rats

The synbiotic mixture of Bacillus licheniformis and Saccharomyces cerevisiae extract aggravates dextran sulfate sodium induced colitis in rats

BACKGROUND

Uncertain effects of probiotics and/or prebiotics have been reported in experimental and clinical colitis. This study aims to examine the effects of a synbiotic combination comprising Bacillus licheniformis DSM 17236 and Saccharomyces cerevisiae cell wall extract on dextran sulfate sodium (DSS)-induced colitis in Sprague Dawley rats.

METHODS

Acute colitis was induced in rats by oral administration of DSS 3.5% for 7 days. Fifty rats were divided equally into five groups; one control group and the other groups were induced with colitis and treated with or without the tested synbiotic, mixed with diet, for 28 days and sulfasalazine (100 mg/kg) via intragastric tube once daily for 14 days.

RESULTS

Symptomatically, the synbiotic administration raised the disease activity index (DAI) to comparable scores of the DSS group, specially from the 2nd to 7th days post DSS intoxication. It also induced a significant (p < 0.05) amplification of WBCs, myeloperoxidase (MPO), malondialdehyde (MDA), nuclear factor kappa B (NF-kB) expression and proinflammatory cytokines tumor necrosis factor alpha (TNFα), interferon gamma (INFγ), and interleukin-1 beta (IL-1β) while depressed the antioxidant enzymes glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) when compared with the DSS and control groups. The DSS intoxicated and Synbiotic+DSS groups showed desquamations of the covering epithelium, noticeable diffuse leukocytic infiltrations, sever catarrhal enteritis, ischemic colitis with diffuse coagulative necrosis of the entire colonic mucosa. Contrarily, sulfasalazine proved to be effective in the reduction of the tested inflammatory markers and the pathological degenerative changes of the DSS ulcerative colitis.

CONCLUSION

The examined synbiotic did not ameliorate but aggravated the DSS-induced colitis, so it should be subjected to intensive experimental and clinical testing before their use in animals and human.

Animal Models and Pathogenesis of Ulcerative Colitis

Background

Ulcerative colitis (UC) is a kind of inflammatory bowel disease which is needed to be predicted.

Objective

To analyze various animal models of UC conditions and summarizes the animal selection, model progression, and pathogenic mechanisms of UC animal models.

Methods

We surveyed the research papers published in PubMed, Google Scholar, Baidu Scholar, CNKI, SciFinder, and Web of Science in the past 5 years and discussed the experimental animals, modeling methods, and pathogenic mechanisms.

Results

In the selection of experimental animals, rats are considered the best experimental animals. The mainstream modeling methods can be categorized into the chemical stimulation method, immune stimulation method, and compound method, among which the compound method is the most successful. In the study of the pathogenesis of UC, the pathogenesis of UC is due to various pathogenic factors, such as nitric oxide (NO), prostaglandins (PG), proinflammatory factors (IL, TNF-α), and intestinal flora.

Conclusion

The method of building an animal model of UC is well-established, providing a more targeted selection of animal models for future related experiments.

Fingolimod ameliorates acetic acid-induced ulcerative colitis: An insight into its modulatory impact on pro/anti-inflammatory cytokines and AKT/mTOR signalling

BACKGROUND

Because of the approved immunomodulatory activities of fingolimod, the current study aimed at studying the curative potential of fingolimod against experimentally induced ulcerative colitis (UC) via modulating pro/anti-inflammatory cytokines release and AKT/mTOR signalling.

METHODS

UC was induced in rats by intracolonic instillation of acetic acid. Fingo (0.5 mg/kg/day, p.o.) was given for 8 consecutive days that started 48 h after UC induction.

RESULTS

Fingolimod increased body weight growth rate and colon body/weight and colon weight/length indices compared to the UC group. Fingolimod significantly decreased clinical evaluation score and macroscopic score compared to the UC group. The curative potential of fingolimod was further confirmed by histopathological examination revealing marked attenuation of mucosal injury and inflammatory cells infiltration. Fingolimod significantly decreased colon malondialdehyde content and increased colon glutathione contents compared to the UC group. Fingolimod also significantly decreased the expressions of pro-inflammatory cytokines interleukin-9 and T-helper 17 along with increasing the expression of anti-inflammatory interleukin-10 and transforming growth factor-β compared to the UC group. In addition, fingolimod decreased the expressions of AKT and mTOR compared to the UC group.

CONCLUSION

Fingolimod attenuated acetic acid-induced UC through its immunomodulatory effect by shifting the balance to favour anti-inflammatory cytokine production rather than pro-inflammatory cytokines and modulating the AKT/mTOR signalling.

Gegen Qinlian Decoction Relieves Ulcerative Colitis via Adjusting Dysregulated Nrf2/ARE Signaling

Objective

Oxidative stress has been proven to be essential in the pathogenesis of ulcerative colitis (UC). Therefore, this study was designed to investigate the effect of Gegen Qinlian decoction (GQ) on the Nrf2 pathway in the treatment of UC and explore the potential mechanism.

Methods

The UC rat model was induced by 5% dextran sodium sulfate (DSS) aqueous solution, and UC rats were treated with GQ orally. The effect of GQ on UC rats was recorded. Human clonal colon adenocarcinoma cells (Caco-2) stimulated by tumor necrosis factor-α (TNF-α) were employed in this study. After being stimulated with TNF-α for 2 hours, Caco-2 cells were cultured with GQ or its major components (puerarin, baicalin, berberine, and liquiritin) for 22 hours. In addition, the Nrf2 gene of Caco-2 cells was silenced and then cultured with GQ for 22 hours. The contents of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) in colonic tissues and Caco-2 cells were detected by assay kits. Reactive oxygen species (ROS) in Caco-2 cells were analyzed by flow cytometry. Quantitative real-time PCR and western blot were employed to detect the mRNA and protein expression of Nrf2 and its related target genes in colon tissues and Caco-2 cells.

Results

GQ alleviated the injured colonic mucosa and activated the expression of Nrf2 in UC rats. In TNF-α stimulated Caco-2 cells and Nrf2 silenced Caco-2 cells, GQ also reversed the inhibitory effect of Nrf2. Furthermore, the major components of GQ could activate Nrf2 signaling in TNF-α stimulated cells as well. Moreover, the contents of SOD, GSH, MDA, and ROS were restored to normal after treatment with GQ or its major components. Among these components, puerarin, berberine, and liquiritin appear to have a better effect on activating Nrf2 in vitro. Overall, GQ can alleviate UC by increasing the activity of Nrf2/ARE signaling and enhancing the effect of antioxidant stress.

A Novel Role of Dapagliflozin in Mitigation of Acetic Acid-Induced Ulcerative Colitis by Modulation of Monocyte Chemoattractant Protein 1 (MCP-1)/Nuclear Factor-Kappa B (NF-κB)/Interleukin-18 (IL-18)

Colon illnesses, particularly ulcerative colitis, are considered a major cause of death in both men and women around the world. The present study investigated the underlying molecular mechanisms for the potential anti-inflammatory effect of Dapagliflozin (DAPA) against ulcerative colitis (UC) induced by intracolonic instillation of 3% v/v acetic acid (AA). DAPA was administered to rats (1 mg/kg, orally) for two weeks during the treatment regimen. Interestingly, compared to the normal group, a marked increase in the index of colon/body weight, colon weight/colon length ratio, serum lactate dehydrogenase (LDH), and C-reactive protein (CRP), besides decrease in the serum total antioxidant capacity (TAC), were reported in the AA control group (p ˂ 0.05). Elevation in colon monocyte chemoattractant protein (MCP1), Interleukin 18 (IL-18), and inflammasome contents were also reported in the AA control group in comparison with the normal group. In addition, colon-specimen immunohistochemical staining revealed increased expression of nuclear factor-kappa B (NF-κB) and Caspase-3 with histopathological changes. Moreover, DAPA significantly (p ˂ 0.05) reduced the colon/body weight index, colon weight/colon length ratio, clinical evaluation, and macroscopic scoring of UC, and preserved the histopathological architecture of tissues. The inflammatory biomarkers, including colon MCP1, IL-18, inflammasome, Caspase-3, and NF-κB, were suppressed following DAPA treatment and oxidants/antioxidants hemostasis was also restored. Collectively, the present data demonstrate that DAPA represents an attractive approach to ameliorating ulcerative colitis through inhibiting MCP1/NF-κB/IL-18 pathways, thus preserving colon function. Antioxidant, anti-inflammatory, and anti-apoptotic properties of DAPA are implicated in its observed therapeutic benefits.

A novel role of pirfenidone in attenuation acetic acid induced ulcerative colitis by modulation of TGF-β1 / JNK1 pathway

Colon diseases are a major health burden, particularly ulcerative colitis, in both men and women worldwide. Environmental and genetic factors in various colonic pathologies influence the onset and outcome of diseases. As the evidence from recent research is considered, the importance of inflammation in the onset, progression, and outcome is gaining more traction. The goal of this study was to see if pirfenidone could treat ulcerative colitis (UC) and if so, what mechanisms were involved. By intracolonic instillation [2 ml, 3 percent v/v acetic acid (AA)], ulcerative colitis was induced. Pirfenidone was administered to rats in different experimental groups (125 or 250 and 500 mg/kg, orally) for two weeks. Compared to normal group, the AA group showed an increase in colon weight, length, body weight, clinical evaluation, and macroscopic scoring of UC, serum lactate dehydrogenase, C-reactive protein, malondialdehyde, while decreasing serum total antioxidant capacity. Significant increases in colon Jun N terminal kinase1 (JNK1), transforming growth factor-beta (TGF-β1), interleukin 1 beta (IL1β), and Caspase-3 content. Furthermore, immunohistochemical staining revealed increased nuclear factor kappa B (NF-κB) expression along with histopathological changes. Pirfenidone inhibited inflammatory biomarkers release and restored oxidants/antioxidants hemostasis. In a dose-dependent manner, pirfenidone treatment showed a significantly decrease in all of these parameters. In addition, pirfenidone has significantly preserved the histopathological architecture of tissues. Current data demonstrate that Pirfenidone protects against AA-induced UC by modulating the TGF-β1/JNK1 and Caspase-3 pathways. Pirfenidone's antioxidant, anti-inflammatory, and anti-apoptotic properties are thought to be responsible for its therapeutic benefit.

Evaluation of the therapeutic effects of mycophenolate mofetil targeting Nrf-2 and NLRP3 inflammasome in acetic acid induced ulcerative colitis in rats

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that increases the risk of colorectal cancer. UC is highly associated with the disturbance of the immune system leading to oxidative stress and chronic inflammation of intestine. Therefore, the current study was conducted to investigate the potential anti-oxidant and anti-inflammatory effects of MMF against acetic acid-induced UC that might be associated with the regulation of Nrf-2 and NLRP3 inflammasome signaling. UC was induced in Sprague-Dawley rats by intracolonic instillation of acetic acid. Forty-eight hours post UC induction, MMF (50 mg/kg/day, orally) was given for 8 consecutive days. Then, colon tissues and blood samples were collected. Results showed that MMF significantly attenuated the acetic acid-induced functional, biochemical, and inflammatory injuries in colon. MMF significantly decreased oxidative stress as indicated by the decreased malondialdehyde concentration and the increased total antioxidant capacity, glutathione, catalase, and superoxide dismutase concentrations in colon tissues. MMF also significantly increased Nrf-2 and decreased NLRP3 inflammasome expressions. Moreover, MMF decreased expression of interferon-gamma and increased expression of interferon-alpha. MMF also significantly decreased expression of pro-inflammatory cytokines, interleukin (IL)-1β and IL-18. These results suggest that MMF has antioxidant and anti-inflammatory effects against acetic acid-induced UC through the upregulation of Nrf-2, and INF-α expression in addition to the suppression of NLRP3 inflammasome and subsequent release of IL1β, IL-18 and INF-γ.

The protective effect of Lactobacillus versus 5-aminosalicylic acid in ulcerative colitis model by modulation of gut microbiota and Nrf2/Ho-1 pathway

AIMS

Ulcerative colitis (UC) has many complications, from colonic damage to colorectal cancer. The mystery of both etiology and effective treatment of UC still challenging process. The role of gut microbiota in UC is still unclear. In the current study we compare the difference in gut microbiota abundance in both UC and normal colon besides the therapeutic effect of Lactobacillus spp. in treating UC versus the standard drug.

MATERIALS AND METHODS

The experimental panel included five group of rats; normal control, UC diseased rats, sterilizing rats, ASA treated and Lactobacillus treated. The change in the microbiota abundance was investigated using conventional and real time PCR. In parallel, clinical evaluation of UC and macroscopic examination scoring was also done. Colonic oxidants/antioxidant stress biomarkers; MDA, GSH, catalase, myeloperoxidase activity, and SOD activity were assessed. Colon Nrf2, HO-1 contents and TNF-α was evaluated.

KEY FINDINGS

The current study revealed a significant difference in the relative abundance of microbiota where, UC is associated with massive increase of E. coli and Fusobacterium spp., while enormous decrease in Bifidobacteria spp. in contrast with negative control. Both 5-ASA and Lactobacillus show a significant amelioration of all antioxidant enzymes and marked decline of inflammatory and oxidative stress markers. Both Lactobacillus and 5-ASA show significant increase of NrF2 and HO-1 and marked decrease of TNF-α.

SIGNIFICANCE

Lactobacillus spp. exerted a beneficial effect on the inflammation, oxidative stress and the symbiosis of gut microbiota that improve structural intestinal defect and promote healing in UC.

Mitigation of Radiation-induced Gastrointestinal System Injury using Resveratrol or Alpha-lipoic Acid: A Pilot Histopathological Study

AIM

In this study, we aimed to determine possible mitigation of radiationinduced toxicities in the duodenum, jejunum and colon using post-exposure treatment with resveratrol and alpha-lipoic acid.

BACKGROUND

After the bone marrow, gastrointestinal system toxicity is the second critical cause of death following whole-body exposure to radiation. Its side effects reduce the quality of life of patients who have undergone radiotherapy. Resveratrol has an antioxidant effect and stimulates DNA damage responses (DDRs). Alpha-lipoic acid neutralizes free radicals via the recycling of ascorbic acid and alpha-tocopherol.

OBJECTIVE

This study is a pilot investigation of the mitigation of enteritis using resveratrol and alpha-lipoic acid following histopathological study.

METHODS

60 male mice were randomly assigned to six groups; control, resveratrol treatment, alpha-lipoic acid treatment, whole-body irradiation, irradiation plus resveratrol, and irradiation plus alpha-lipoic acid. The mice were irradiated with a single dose of 7 Gy from a cobalt-60 gamma-ray source. Treatment with resveratrol or alpha-lipoic acid started 24 h after irradiation and continued for 4 weeks. All mice were sacrificed after 30 days for histopathological evaluation of radiation-induced toxicities in the duodenum, jejunum and colon.

RESULTS AND DISCUSSION

Exposure to radiation caused mild to severe damages to vessels, goblet cells and villous. It also led to significant infiltration of macrophages and leukocytes, especially in the colon. Both resveratrol and alpha-lipoic acid were able to mitigate morphological changes. However, they could not mitigate vascular injury.

CONCLUSION

Resveratrol and alpha-lipoic acid could mitigate radiation-induced injuries in the small and large intestine. A comparison between these agents showed that resveratrol may be a more effective mitigator compared to alpha-lipoic acid.

Activation of integrated stress response pathway regulates IL-1β production through posttranscriptional and translational reprogramming in macrophages

Immune cells sense and programme its cellular machinery appropriately to the environmental changes through the activation of cytoprotective adaptive pathway so-called the "integrated stress response (ISR)". However, the mechanisms implicated in ISR-induced protective responses are poorly understood. Here, we show that ISR activation by arsenite (Ar) results in suppression of IL-1β production in macrophages and inhibition of DSS-induced colitis in a murine model through a novel posttranscriptional and translation regulatory (PTR) mechanism. Ar triggers PTR events through eIF2α-phosphorylation, which results in the attenuation of active polysome formation leading to the accumulation of translationally stalled IL-1β mRNAs. Translationally stalled IL-1β mRNAs recruit RNA-binding proteins (TIA-1/TIAR), resulting in the formation of RBP-RNA complexes known as stress granules (SGs). The SGs bound IL-1β mRNAs might undergo degradation through induction of autophagy. Also, we show that Ar posttranslationally impairs processing and secretion of IL-1β by diminishing inflammasome activation. Altogether, this study unveils a novel mechanism of IL-1β regulation and further suggests that pharmacological activation of cytoprotective ISR pathway might provide an effective therapeutic intervention against inflammatory diseases.

Effect of a probiotic beverage consumption (Enterococcus faecium CRL 183 and Bifidobacterium longum ATCC 15707) in rats with chemically induced colitis

Background

Some probiotic strains have the potential to assist in relieving the symptoms of inflammatory bowel disease. The impact of daily ingestion of a soy-based product fermented by Enterococcus faecium CRL 183 and Lactobacillus helveticus 416 with the addition of Bifidobacterium longum ATCC 15707 on chemically induced colitis has been investigated thereof within a period of 30 days.

Methods

Colitis was induced by dextran sulfate sodium. The animals were randomly assigned into five groups: Group C: negative control; Group CL: positive control; Group CLF: DSS with the fermented product; Group CLP: DSS with the non-fermented product (placebo); Group CLS: DSS with sulfasalazine. The following parameters were monitored: disease activity index, fecal microbial analyses, gastrointestinal survival of probiotic microorganisms and short-chain fatty acids concentration in the feces. At the end of the protocol the animals’ colons were removed so as to conduct a macroscopical and histopathological analysis, cytokines and nitrite quantification.

Results

Animals belonging to the CLF group showed fewer symptoms of colitis during the induction period and a lower degree of inflammation and ulceration in their colon compared to the CL, CLS and CLP groups (p<0.05). The colon of the animals in groups CL and CLS presented severe crypt damage, which was absent in CLF and CLP groups. A significant increase in the population of Lactobacillus spp. and Bifidobacterium spp. at the end of the protocol was verified only in the CLF animals (p<0.05). This group also showed an increase in short-chain fatty acids (propionate and acetate). Furthermore, the intestinal survival of E. faecium CRL 183 and B. longum ATCC 15707 in the CLF group has been confirmed by biochemical and molecular analyzes.

Conclusions

The obtained results suggest that a regular intake of the probiotic product, and placebo to a lesser extent, can reduce the severity of DSS-induced colitis on rats.

Does oral exposure to cadmium and lead mediate susceptibility to colitis? The dark-and-bright sides of heavy metals in gut ecology

Although the heavy metals cadmium (Cd) and lead (Pb) are known environmental health concerns, their long-term impacts on gut ecology and susceptibility to gastrointestinal autoimmune diseases have not been extensively investigated. We sought to determine whether subchronic oral exposure to Cd or Pb is a risk factor for the development and progression of inflammatory bowel disease (IBD). Mice were exposed to various doses of CdCl2 or PbCl2 in drinking water for 1, 4 or 6 weeks prior to infection with Salmonella, the induction of colitis with dextran sodium sulfate (DSS) or trinitrobenzene sulfonic acid (TNBS). In human cell-based models, exposure to Cd and Pb is associated with reduced transepithelial electric resistance and changes in bacteria-induced cytokine responses. Although 1- and 6-week exposures did not have clear effects on the response to Salmonella infectious challenges, 1-week short-term treatments with CdCl2 tended to enhance intestinal inflammation in mice. Unexpectedly, subchronic exposure to Cd and (to a lesser extent) Pb significantly mitigated some of the symptoms of DSS-induced colitis and reduced the severity of TNBS colitis in a dose-dependent manner. The possible adaptive and immunosuppressive mechanisms by which heavy metals might reduce intestinal inflammation are explored and discussed.

Intraperitoneal administration of butyrate prevents the severity of acetic acid colitis in rats

Intrarectal infusion of butyrate improves colorectal disorders including ulcerative colitis (UC). However, it is not established whether systemically administered butyrate benefits such patients. The current study aimed at exploring and comparing the potential of intraperitoneally, intrarectally, and orally administered butyrate against acetic acid (AA)-induced UC in rats. Intrarectal administration of 2 ml of 50% AA was done after or without prior treatment of rats for 7 consecutive days with 100 mg/kg sodium butyrate (SB) intraperitoneally, intrarectally, or orally. Rats were sacrificed after 48 h of AA-treatment. Subsequently, colon sections were processed routinely for histopathological examination. We clinically observed diarrhea, loose stools, and hemoccult-positive stools, and histologically, epithelial loss and ulceration, crypt damage, goblet cell depletion, hemorrhage, and mucosal infiltration of inflammatory cells. The changes were significantly reduced by intraperitoneal, intrarectal, or oral butyrate, with intraperitoneal butyrate exhibiting the highest potency. It is concluded that intraperitoneal administration of butyrate abrogates the lesions of AA-induced UC and its potency surpasses that of intrarectal or oral butyrate.

Increased susceptibility to dextran sulfate sodium induced colitis in the T cell protein tyrosine phosphatase heterozygous mouse

T cell protein tyrosine phosphatase (TC-PTP / PTPN2) is an enzyme that is essential for the proper functioning of the immune system and that participates in the control of cell proliferation, and inflammation. We previously observed that TC-PTP^−/− mice display various immunodeficiencies, hypersensitivity to LPS and die within three weeks of birth due to anemia and widespread inflammation. A recent analysis of the Wellcome Trust Case Control Consortium (WTCC) genome wide scan data, reported in 2007, indicated a potential role for TC-PTP in inflammatory bowel disease (IBD). To further investigate the potential role of TC-PTP in IBD, we studied heterozygous TC-PTP mutant mice challenged with dextran sulfate sodium (DSS) in their drinking water. In comparison to control animals, we observed significant changes in the colon mucosa of DSS-treated TC-PTP^+/− mice, in the ratio of colon to body weight, as well as an up-regulation of mRNA transcripts for IL-6, IL-23, 1L-12β, IFN-γ, TNF-α. Moreover, up-regulation of serum IL-6 levels in DSS-treated TC-PTP^+/− mice confirms that mice with a single copy of the TC-PTP gene display increased susceptibility to systemic inflammation due to bowel epithelial erosion resulting from DSS challenge. Our findings support the lack of modulation of Janus kinases 1 and 3 (Jak1, Jak3), and the downstream signal transducer and activator of transcription 1,3 and 5 (Stat1, Stat3, Stat 5) by PTPN2 in the development of IBD like condition. Pathological and molecular analysis reveal that the deficiency of TC-PTP results in pro-inflammatory condition in the bowel of heterozygous TC-PTP^+/− mice. These novel findings in TC-PTP hemi-deficiency support the hypothesis that TC-PTP is an important regulator of inflammatory cytokine signaling and that it may be implicated in the pathophysiology of IBD.