Dextran Sulfate Sodium Challenge Research Articles

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

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

Ganoderma Lucidum Extract Modulates Cecal Microbiota Community in Broilers under Dextran Sulfate Sodium Challenge During the Starter Phase

Ganoderma Lucidum Extract Modulates Cecal Microbiota Community in Broilers under Dextran Sulfate Sodium Challenge During the Starter Phase

Treatment with Extracellular Vesicles from Giardia lamblia Alleviates Dextran Sulfate Sodium-Induced Colitis in C57BL/6 Mice.

Inflammatory bowel disease (IBD) is a chronic and recurrent illness of the gastrointestinal tract. Treatment of IBD traditionally involves the use of aminosalicylic acid and steroids, while these drugs has been associated with untoward effects and refractoriness. The absence of effective treatment regimen against IBD has led to the exploration of new targets. Parasites are promising as an alternative therapy for IBD. Recent studies have highlighted the use of parasite-derived substances, such as excretory secretory products, extracellular vesicles (EVs), and exosomes, for the treatment of IBD. In this report, we examined whether EVs secreted by Giardia lamblia could prevent colitis in a mouse model. G. lamblia EVs (GlEVs) were prepared from in vitro cultures of Giardia trophozoites. Clinical signs, microscopic colon tissue inflammation, and cytokine expression levels were detected to assess the effect of GlEV treatment on dextran sulfate sodium (DSS)-induced experimental murine colitis. The administration of GlEVs prior to DSS challenge reduced the expression levels of pro-inflammatory cytokines, including tumor necrosis factor alpha, interleukin 1 beta, and interferon gamma. Our results indicate that GlEV can exert preventive effects and possess therapeutic properties against DSS-induced colitis.

Spirulina platensis aqueous extracts ameliorate colonic mucosal damage and modulate gut microbiota disorder in mice with ulcerative colitis by inhibiting inflammation and oxidative stress.

Ulcerative colitis (UC) is a chronic and recurrent inflammatory bowel disease (IBD) that has become a major gastroenterologic problem during recent decades. Numerous complicating factors are involved in UC development such as oxidative stress, inflammation, and microbiota disorder. These factors exacerbate damage to the intestinal mucosal barrier. Spirulina platensis is a commercial alga with various biological activity that is widely used as a functional ingredient in food and beverage products. However, there have been few studies on the treatment of UC using S. platensis aqueous extracts (SP), and the underlying mechanism of action of SP against UC has not yet been elucidated. Herein, we aimed to investigate the modulatory effect of SP on microbiota disorders in UC mice and clarify the underlying mechanisms by which SP alleviates damage to the intestinal mucosal barrier. Dextran sulfate sodium (DSS) was used to establish a normal human colonic epithelial cell (NCM460) injury model and UC animal model. The mitochondrial membrane potential assay 3-‍‍(4,5-dimethylthiazol-2-yl)-2,‍5-diphenyltetrazolium bromide (MTT) and staining with Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) and Hoechst 33258 were carried out to determine the effects of SP on the NCM460 cell injury model. Moreover, hematoxylin and eosin (H&E) staining, transmission electron microscopy (TEM), enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qPCR), western blot, and 16S ribosomal DNA (rDNA) sequencing were used to explore the effects and underlying mechanisms of action of SP on UC in C57BL/6 mice. In vitro studies showed that SP alleviated DSS-induced NCM460 cell injury. SP also significantly reduced the excessive generation of intracellular reactive oxygen species (ROS) and prevented mitochondrial membrane potential reduction after DSS challenge. In vivo studies indicated that SP administration could alleviate the severity of DSS-induced colonic mucosal damage compared with the control group. Inhibition of inflammation and oxidative stress was associated with increases in the activity of antioxidant enzymes and the expression of tight junction proteins (TJs) post-SP treatment. SP improved gut microbiota disorder mainly by increasing antioxidant enzyme activity and the expression of TJs in the colon. Our findings demonstrate that the protective effect of SP against UC is based on its inhibition of pro-inflammatory cytokine overproduction, inhibition of DSS-induced ROS production, and enhanced expression of antioxidant enzymes and TJs in the colonic mucosal barrier.

L-Isoleucine Administration Alleviates DSS-Induced Colitis by Regulating TLR4/MyD88/NF-κB Pathway in Rats.

Inflammatory bowel disease (namely, colitis) severely impairs human health. Isoleucine is reported to regulate immune function (such as the production of immunoreactive substances). The aim of this study was to investigate whether l-isoleucine administration might alleviate dextran sulfate sodium (DSS)-induced colitis in rats. In the in vitro trial, IEC-18 cells were treated by 4 mmol/L l-isoleucine for 12 h, which relieved the decrease of cell viability that was induced by TNF-α (10 ng/ml) challenge for 24 h (P <0.05). Then, in the in vivo experiment, a total of 44 Wistar rats were allotted into 2 groups that were fed l-isoleucine-supplemented diet and control diet for 35 d. From 15 to 35 d, half of the rats in the 2 groups drank the 4% DSS-adding water. Average daily gain, average daily feed intake and feed conversion of rats were impaired by DSS challenge (P <0.05). Drinking the DSS-supplementing water also increased disease activity index (DAI) and serum urea nitrogen level (P <0.05), shortened colonic length (P <0.05), impaired colonic enterocyte apoptosis, cell cycle, and the ZO-1 mRNA expression (P <0.05), increased the ratio of CD11c-, CD64-, and CD169-positive cells in colon (P <0.05), and induced extensive ulcer, infiltration of inflammatory cells, and collagenous fiber hyperplasia in colon. However, dietary l-isoleucine supplementation attenuated the negative effect of DSS challenge on growth performance (P <0.05), DAI (P <0.05), colonic length and enterocyte apoptosis (P <0.05), and dysfunction of colonic histology, and downregulated the ratio of CD11c-, CD64-, and CD169-positive cells, pro-inflammation cytokines and the mRNA expression of TLR4, MyD88, and NF-κB in the colon of rats (P <0.05). These results suggest that supplementing l-isoleucine in diet improved the DSS-induced growth stunting and colonic damage in rats, which could be associated with the downregulation of inflammation via regulating TLR4/MyD88/NF-κB pathway in colon.

Bacillus subtilis-Fermented Products Ameliorate the Growth Performance, Alleviate Intestinal Inflammatory Gene Expression, and Modulate Cecal Microbiota Community in Broilers during the Starter Phase under Dextran Sulfate Sodium Challenge.

The aim of this study was to evaluate the effects of B. subtilis-fermented products (BSFP) on growth performance, intestinal inflammatory gene expression, and cecal microbiota community in broilers challenged with dextran sulfate sodium (DSS) in a 14-day experiment. A total of 32, 1-day-old male broiler chickens (Ross 308), were randomly divided into four groups of eight birds per group and reared individually (n=8). The treatments consisted of a control diet without supplementation and DSS challenge, control diet plus 1.5% DSS, control diet plus 1 g/kg BSFP in combination with 1.5% DSS, and control diet plus 3 g/kg of BSFP in combination with 1.5% DSS. The results showed that BSFP supplementation (1 and 3 g/kg) partially improved body weight and average daily gain in broilers under DSS challenge. Relative to DSS treatment alone, BSFP supplementation dose-dependently increased the body weight of broilers at 7 days of age, with the average daily gain being at 1 to 7 days of age. BSFP supplementation (1 and 3 g/kg) alleviated intestinal inflammatory gene expression in broilers under DSS challenge. The richness and evenness of bacterial species in cecal digesta increased in a dose-dependent manner in the groups treated with BSFP (1 and 3 g/kg) in combination with DSS challenge, compared with the control group. Unweighted principal coordinate analysis indicated distinct clusters separating the group treated with 3 g/kg of BSFP in combination with DSS challenge from the other three groups. The abundance of short-chain fatty acid-producing bacteria (genus Ruminococcaceae_unclassified) increased and that of mucindegrading bacteria (genus Ruminococcus torques group) decreased in the cecal digesta of broilers fed 3 g/kg of BSFP, compared with the control group. In conclusion, BSFP supplementation dose-dependently improved growth performance, reduced gut inflammation, and regulated the cecal microbiota of broilers exposed to DSS challenge during the starter phase.

Fibrin(ogen) Promotes Immune Cell Infiltration, Dysbiosis and ROS Production in Experimental Colitis

Elevated stool fibrinogen has recently been shown to predict disease course in ulcerative colitis (UC), suggesting that fibrin(ogen) in the colitis microenvironment promotes UC pathogenesis. This conclusion is consistent with previous studies from our laboratory showing that fibrin(ogen)/leukocyte interactions mediated by the integrin receptor α Mβ 2 promote experimental colitis and colitis-associated cancer, but the mechanisms are not well defined. To delineate the mechanism coupling fibrinogen to colitis pathogenesis, we induced colitis in Fib WT and mice carrying a mutant fibrinogen lacking the α Mβ 2 binding motif (Fibg 390-396A) with Dextran Sulfate Sodium (DSS). We performed flow cytometric, protein analyses of colons and fecal microbiome and metabolomics analyses after DSS exposure. Five days after DSS challenge, a timepoint prior to significant epithelial damage, we observed significantly diminished infiltration of natural killer cells, T cells, dendritic cells, macrophages and neutrophils in colons harvested from DSS-challenged Fibg 390-396A mice relative to Fib WT mice. We also observed significantly diminished proinflammatory cytokine production by NK cells, macrophages and dendritic cells isolated from DSS-challenged Fibg 390-396A colons. It is well-established that the microbiome composition is a major determinant of colitis in humans and mice. One mechanism by which microbiome contents alter the course of colitis is by the elaboration of certain fecal metabolites. NMR-based fecal metabolomics analyses demonstrated no significant changes in short-chain fatty acids (acetate, propionate, and butyrate) and various amino acids (valine, proline, alanine) however we found significantly less uracil in fecal from Fibg 390-296A relative to Fib WT mice following DSS exposure. Uracil is a key ligand for Duox2 (dual NADPH oxidase), a gut epithelial specific enzyme, that drives reactive oxygen species production by gut epithelial in response to dysbiosis. Notably, Duox2 is the highest induced gene in inflammatory bowel disease (IBD) and has been identified as a risk gene. Our molecular analyses showed no difference in colonic Duox2 expression between genotypes at baseline, but Duox2 expression significantly increased in Fib WT relative to Fibg 390-296A after just 5 days of DSS exposure. Further western blot analyses revealed that Duox2 expression only in the colonic epithelial cells and not in the lamina propria cells. To determine if fibrinogen cause dysbiosis in DSS-induced colitis model, we performed shotgun sequencing on fecal samples from Fib WT and Fibg 390-396A mice at baseline and after 7 days of DSS challenge. Interesting shotgun sequencing analyses revealed major fibrin genotype dependent significant differences in the microbiomes of Fib WT and Fibg 390-396A mice at baseline as well as following DSS challenge. Our studies are the first to show that fibrin(ogen) is a major determinant of the gut-microbiome in the context of experimental colitis. Altogether, these studies demonstrate that fibrin(ogen) in the colitis microenvironment promotes the infiltration and activation of multiple leukocyte subsets that drive colitis pathogenesis. These results also suggest that fibrin(ogen) promotes colitis-associated dysbiosis and Duox2 expression, leading to ROS production that contributes to colitis pathogenesis and possibley tumorigenesis. Overall, these studies suggest that fibrin(ogen)-α Mβ 2 interactions represent an attractive therapeutic target for IBD without incurring the potential bleeding risks associated with anticoagulants or other modalities targeting fibrin deposition. DisclosuresNo relevant conflicts of interest to declare.

Kaempferol Alleviates Murine Experimental Colitis by Restoring Gut Microbiota and Inhibiting the LPS-TLR4-NF-κB Axis.

Intestinal microbiota dysbiosis is an established characteristic of ulcerative colitis (UC). Regulating the gut microbiota is an attractive alternative UC treatment strategy, considering the potential adverse effects of synthetic drugs used to treat UC. Kaempferol (Kae) is an anti-inflammatory and antioxidant flavonoid derived from a variety of medicinal plants. In this study, we determined the efficacy and mechanism of action of Kae as an anti-UC agent in dextran sulfate sodium (DSS)-induced colitis mice. DSS challenge in a mouse model of UC led to weight loss, diarrhea accompanied by mucous and blood, histological abnormalities, and shortening of the colon, all of which were significantly alleviated by pretreatment with Kae. In addition, intestinal permeability was shown to improve using fluorescein isothiocyanate (FITC)–dextran administration. DSS-induced destruction of the intestinal barrier was also significantly prevented by Kae administration via increases in the levels of ZO-1, occludin, and claudin-1. Furthermore, Kae pretreatment decreased the levels of IL-1β, IL-6, and TNF-α and downregulated transcription of an array of inflammatory signaling molecules, while it increased IL-10 mRNA expression. Notably, Kae reshaped the intestinal microbiome by elevating the Firmicutes to Bacteroidetes ratio; increasing the linear discriminant analysis scores of beneficial bacteria, such as Prevotellaceae and Ruminococcaceae; and reducing the richness of Proteobacteria in DSS-challenged mice. There was also an evident shift in the profile of fecal metabolites in the Kae treatment group. Serum LPS levels and downstream TLR4-NF-κB signaling were downregulated by Kae supplementation. Moreover, fecal microbiota transplantation from Kae-treated mice to the DSS-induced mice confirmed the effects of Kae on modulating the gut microbiota to alleviate UC. Therefore, Kae may exert protective effects against colitis mice through regulating the gut microbiota and TLR4-related signaling pathways. This study demonstrates the anti-UC effects of Kae and its potential therapeutic mechanisms, and offers novel insights into the prevention of inflammatory diseases using natural products.

Ripened Pu-erh Tea Extract Promotes Gut Microbiota Resilience against Dextran Sulfate Sodium Induced Colitis.

Ripened Pu-erh tea (RPT) has been shown to be an effective natural ingredient to defend against experimentally induced colitis. We hypothesized that RPT would alleviate dextran sulfate sodium (DSS) induced colitis via modulating intestinal microbiota. The effect of RPT on mice gut microbiota was evaluated using 16S rRNA gene amplicon sequencing, broad-spectrum antibiotic (ABX) treatment, and fecal microbiota transplantation (FMT). Pretreatment with RPT enhanced intestinal barrier function, reduced colonic and serum proinflammatory cytokine and macrophage infiltration, and preserved the resilience of gut microbiota in mice during a DSS challenge. Administration of either RPT-regulated or healthy control-derived gut microbiota showed similar protection against colitis, and such protection could not be recapitulated with fecal microbiota from ABX-treated mice, suggesting a key role of protective consortium in the disease protection. Mechanistically, cecal contents of short-chain fatty acids (SCFAs) and colonic peroxisome proliferator activated receptor-γ (PPAR-γ) expression in colitis mice increased significantly by RPT intervention. Collectively, RPT treatment improved DSS-induced colitis by partially reversing the dysbiosis state of gut microbiota, which might be associated with an increase in SCFA level and PPAR-γ expression.

Potential role of Lactobacillus plantarum in colitis induced by dextran sulfate sodium through altering gut microbiota and host metabolism in murine model.

Inflammatory bowel disease (IBD) is a chronic lifelong disease characterized by inflammation of the gastrointestinal tract. Although more and more treatment options serve IBD, there is still no cure. It is important to find an effective treatment for IBD. This study aims to investigate whether Lactobacillus plantarum (L. plantarum) could alleviate colitis induced by dextran sulfate sodium (DSS). Following the DSS challenge, L. plantarum on DSS-mediated inflammatory colon lesions in mice, and L. plantarum therapy heightened the relative abundance of the colon-resident Actinobacteria. Analysis of serum metabolomics also indicated that the content of MG (18:4 (6Z, 9Z, 12Z, 15Z)/0:0/0:0) was increased in response to L. plantarum therapy, and this was also the case for indolepyruvate and 1-hydroxyibuprofen. However, 13-oxooctadecadienoic acid (13-oxoODE) and indolylacryloylglycine content fell following the DSS challenge. Based on these results, the study elucidates the mitigatory effects of L. plantarum in colitis, which depend on its regulation of the colonic microbial community and its modification of serum metabolites. The results revealed that L. plantarum mitigated inflammatory colon lesions, reprogrammed the microbial community and altered the level of serum metabolites in a murine model challenged with DSS. The study may present a potential therapeutic strategy for colitis.

Ethanol extract of Centella asiatica alleviated dextran sulfate sodium-induced colitis: Restoration on mucosa barrier and gut microbiota homeostasis

Ethnopharmacological relevanceUlcerative colitis (UC) is a relapsing inflammatory disease that still demands for effective remedies due to various adverse effects of the current principal treatments. Centella asiatica is a traditional medical herb with long application history in anti-inflammation. Aim of the studyTo explore the anti-inflammatory effect and possible mechanism of C. asiatica ethanol extract (CA) in a murine colitis model induced by dextran sulfate sodium (DSS). Materials and methodsCA was analyzed by high performance liquid chromatograph (HPLC). The colitis model was induced by free access to 3% DSS in distilled water for 7 days. CA (100, 200, and 400 mg/kg) and 5-aminosalicylic acid (5-ASA, 400 mg/kg) were administrated by gavage during the 7-day DSS challenge. At the end of experiment, mice were sacrificed and the brain, colon and cecum contents were harvested for analysis. Colitis was evaluated by disease activity index (DAI), colon length and colon lesion macroscopic score with hematoxylin-eosin staining. Myeloperoxidase (MPO) activity in colon and 5-hydroxytryptamine (5-HT) in brain were determined by ELISA. Tight junction protein expressions (ZO-1, E-Cadherin, Claudin-1) and c-Kit in colon were assessed by western blot and immunohistochemistry, respectively. Microbiota of cecum content was analyzed by 16S rRNA sequencing. ResultsData showed that with recovery on the colon length and histological structure, CA prominently decreased DAI and macroscopic score for lesion in the suffering mice. CA relieved the colitis by suppressing inflammatory cell infiltration with decreased MPO activity in the colon, and up-regulated the expression of tight junction protein (ZO-1, E-cadherin) to enhance the permeability of intestinal mucosa. Moreover, CA restored intestinal motility by promoting c-Kit expression in the colon and 5-HT in the brain. Moreover, CA was able to reshape the gut microbiota in the suffering mice. It increased the α-diversity and shifted the community by depleting the colitis-associated genera, Helicobacter, Jeotgalicoccus and Staphylococcus, with impact on several metabolism signaling pathways, which possibly contributes to the renovation on the impaired intestinal mucosal barrier. ConclusionsCA displayed the anti-inflammatory activity against the DSS-induced colitis, which would possibly rely on the restoration on mucosa barrier and gut microbiota homeostasis, highlights a promising application of C. asiatica in the clinical treatment of UC.

MK2 Is Required for Neutrophil-Derived ROS Production and Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic disease that is commonly accompanied by increased inflammatory responses and elevated reactive oxygen species (ROS) of the gastrointestinal tract. Here, we found that MAPK-activated protein kinase 2 (MK2) modulates ROS production and is required for dextran sulfate sodium (DSS)-induced IBD in the mouse model. Genetic ablation of MK2 in the myeloid lineage cells (MK2Lyz2−KO) protected against DSS-induced colitis injury. In response to DSS challenge, compared to MK2lyz2−WT mice, MK2Lyz2−KO mice exhibited less damage of epithelial and goblet cells, decreased generation of interleukin (IL)-6, tumor necrosis factor (TNF)-α, and ROS, as well as reduced Ki67-positive cells and concentrations of myeloperoxidase (MPO) in the intestinal epithelium. Furthermore, upon treatment with formylated peptide N-formyl-methionyl-leucyl-phenylalanine (fMLF), the generation of ROS was attenuated in MK2-deficient neutrophils, in which the phosphorylation of Akt and p38 MAPK was also reduced. Collectively, these findings indicated that MK2 is required for neutrophil-derived ROS production and IBD, and MK2 and ROS are promising therapeutic targets for IBD.

Platelet activating factor receptor acts to limit colitis-induced liver inflammation.

Liver inflammation is a common extraintestinal manifestation in inflammatory bowel disease (IBD), yet, the mechanisms driving gut-liver axis inflammation remain poorly understood. IBD leads to a breakdown in the integrity of the intestinal barrier causing an increase in portal and systemic gut-derived antigens, which challenge the liver. Here, we examined the role of platelet activating factor receptor (PAFR) in colitis-associated liver damage using dextran sulfate sodium (DSS) and anti-CD40-induced colitis models. Both DSS and anti-CD40 models exhibited liver inflammation associated with colitis. Colitis reduced global PAFR protein expression in mouse livers causing an exclusive re-localization of PAFR to the portal triad. The global decrease in liver PAFR was associated with increased sirtuin 1 while relocalized PAFR expression was limited to Kupffer cells (KCs) and co-localized with toll-like receptor 4. DSS activated the NLRP3-inflammasome and increased interleukin (IL)-1β in the liver. Antagonism of PAFR amplified the inflammasome response by increasing NLRP3, caspase-1, and IL-1β protein levels in the liver. LPS also increased NLRP3 response in human hepatocytes, however, overexpression of PAFR restored the levels of NLPR3 and caspase-1 proteins. Interestingly, KCs depletion also increased IL-1β protein in mouse liver after DSS challenge. These data suggest a protective role for PAFR-expressing KCs during colitis and that regulation of PAFR is important for gut-liver axis homeostasis.

Aging Increases the Severity of Colitis and the Related Changes to the Gut Barrier and Gut Microbiota in Humans and Mice.

This study aims to compare intestinal mucosal barrier function in older and young ulcerative colitis (UC) patients and the healthy population, and to explore the possible mechanisms through which aging increases the severity of colitis in mice. The old healthy group showed discontinued tight junction (TJ) strand. The E-cadherin and occludin protein expressions in the colonic tissue of the old healthy subjects were lower than those in the younger healthy people. The protein expressions of E-cadherin and occludin were lower in the old UC patients than in the younger UC patients. In mice, disease activity indexes induced by inflammatory stimulus differed as a function of age. Weight loss level, histological scores, and expression of proinflammatory factors were higher in the dextran sulfate sodium (DSS)-induced group of aged mice than in the young DSS-induced mice. Compared with the results observed in the young DSS-induced mice, the protein expressions of E-cadherin and occludin in the aged DSS-induced mice were lower. Furthermore, significant differences were observed in the composition of the gut microbiota between the young and aged mice. In the aged mice, the fraction of beneficial bacteria (Lactobacillus) was lower before the DSS treatment, while the fraction of the harmful bacteria (Turicibacter, Parasutterella) was higher than that observed in the young mice. After the DSS treatment in the aged mice, the fraction of beneficial bacteria (Odoribacter and Alistipes) was lower, while the fraction of harmful bacteria (Turicibacter) was higher than in the young mice. We demonstrate that the aging of the human colon is characterized by an impairment of the intestinal barrier. Aging leads to more severe disease following DSS challenge. Age-related deterioration of gastrointestinal barrier function and gut microbial dysbiosis may be involved in the pathogenesis of colitis in the aged mice.

Oral delivery of pancreatitis-associated protein by Lactococcus lactis displays protective effects in dinitro-benzenesulfonic-acid-induced colitis model and is able to modulate the composition of the microbiota.

SummaryAntimicrobial peptides secreted by intestinal immune and epithelial cells are important effectors of innate immunity. They play an essential role in the maintenance of intestinal homeostasis by limiting microbial epithelium interactions and preventing unnecessary microbe‐driven inflammation. Pancreatitis‐associated protein (PAP) belongs to Regenerating islet‐derived III proteins family and is a C‐type (Ca+2 dependent) lectin. PAP protein plays a protective effect presenting anti‐inflammatory properties able to reduce the severity of colitis, preserving gut barrier and epithelial inflammation. Here, we sought to determine whether PAP delivered at intestinal lumen by recombinant Lactococcus lactis strain (LL‐PAP) before and after chemically induced colitis is able to reduce the severity in two models of colitis. After construction and characterization of our recombinant strains, we tested their effects in dinitro‐benzenesulfonic‐acid (DNBS) and Dextran sulfate sodium (DSS) colitis model. After the DNBS challenge, mice treated with LL‐PAP presented less severe colitis compared with PBS and LL‐empty‐treated mice groups. After the DSS challenge, no protective effects of LL‐PAP could be detected. We determined that after 5 days administration, LL‐PAP increase butyrate producer's bacteria, especially Eubacterium plexicaudatum. Based on our findings, we hypothesize that a treatment with LL‐PAP shifts the microbiota preventing the severity of colon inflammation in DNBS colitis model. These protective roles of LL‐PAP in DNBS colitis model might be through intestinal microbiota modulation.

A characterization of pro-inflammatory cytokines in dextran sulfate sodium-induced chronic relapsing colitis mice model

Repeated cycles of dextran sulfate sodium (DSS) administration in mice, inducing chronic relapsing colitis, have been used to mimic human ulcerative colitis (UC). However, no systematic characterization of pro-inflammatory cytokines in these DSS mice has been reported. In this study, the development of colitis was examined by assessment of the disease severity and inflammation in the colon of C57BL/6 mice that received DSS. ELISA was used to analyze the levels of pro-inflammatory cytokines in serum, colon, spleen and supernatant of cultured splenocytes. mRNA levels of the above cytokines in colon and mesenteric lymph node (MLN) were measured with RT-PCR. The mice receiving three cycles of 2% DSS over a 43-day period showed a fluctuating appearance of diarrhea and bloody feces, and a significant reduction in body weight and colon length. When compared with normal control mice, an increase in TNF-α level in serum was detected in the DSS mice, along with a decrease in the amounts of TNF-α, IL-17, IL-1β and IL-6 in the colonic tissue. However, mRNA levels of these cytokines were found to be significantly increased in the colon while decreased in the MLN of the colitis mice. Further, the ELISA assay suggested a pronounced increase of TNF-α production by cultured splenocytes with PMA/ionomycin re-stimulation but no increase in its presence in spleen tissue upon DSS challenge. In conclusion, we have systematically demonstrated the dysregulation of pro-inflammatory cytokines in the DSS-induced chronic relapsing colitis model, which will provide markers to test emerging therapeutic strategies by this model.

Platelet Activating Factor Receptor (PAFR) Regulates Colitis‐induced Pulmonary Inflammation

Inflammatory bowel disease (IBD) is a progressive disease that includes Crohn's diseases and ulcerative colitis. Over one third of IBD patients have secondary organ pathologies and pulmonary manifestations are common. The platelet activating factor receptor (PAFR) plays a critical role in regulating inflammation and it is expressed on epithelial cells and neutrophils in both colon and lung. Having identified increased expression of PAFR in both the gastrointestinal (GI) tract and lungs of mice with dextran sulfate sodium (DSS) colitis, we hypothesised that PAFR was a mediator of the pulmonary inflammation associated with colitis. We aimed to elucidate the role of PAFR in gut‐lung inflammatory cross‐talk using of the DSS‐induced experimental model of colitis (7 days). DSS mice were treated with PAFR antagonist CV6209 both intranasally and intravenously and lung, colon and blood were assessed for inflammatory cells and mediators by qPCR, immunoblot, immunohistochemistry and flow cytometry. We demonstrated that DSS‐induced colitis resulted in inflammation in mouse bronchoalveolar lavage fluid (BALF) and lungs, as well as increased PAFR protein levels in lungs and colons. Pulmonary neutrophils in DSS animals showed increased PAFR staining. Bacterial 16S mRNA expression were also increased in mouse lungs after 7 days DSS challenge. Both intravenous and intranasal inhibition of PAFR by CV6209 reduced colitis‐induced numbers of neutrophils, but not macrophages, in mouse lungs. Inhibition of PAFR also reduced levels of TNF and IL‐1b proteins and bacterial 16S expression in mouse lungs. Importantly, intravenous administration of CV6209 reduced colitis pathology, TNF and IL‐1b protein levels in mouse colons after 7 days DSS challenge. In the DSS model, increased PAFR protein expression was associated with inflammasome activation, characterized by increased NLRP3 and mature caspase‐1 proteins, however inhibition of PAFR by CV6209 reduced NLRP3 and caspase‐1 levels after DSS challenge in mouse lungs. In vitro, NLRP3, activated caspase‐1 and secreted IL‐1b protein levels were increased in human alveolar epithelial cell culture (A549) after 24h LPS stimulation, and this was inhibited by treatment with CV6209. These data suggest that PAFR regulates colitis‐induced lung inflammation by IL‐1b protein activation via the NLRP3 inflammasome signalling pathway. PAFR may act as an inflammasome‐activating pattern recognition receptor during mucosal inflammation thus is a potential therapeutic target for lung inflammation associated with colitis and bacteraemia.Support or Funding InformationThis study was supported by a grant from National Health Medical Research Council (NHMRC) AustraliaThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Intestinal Epithelial AMPK Does Not Protect Against High Dose DSS‐Induced Colitis in Mice

AMP‐Activated Protein Kinase (AMPK) is a master regulator of cellular energy status whose activity requires α1 and α2 isoforms of the catalytic subunit. Recent evidence suggested AMPK protects against DSS‐induced colitis using villin‐Cre AMPKα1 knockout mice and nonspecific pharmacological activators. However, previous studies have not tested if both AMPKα isoforms are required for protection as α1/α2 double‐knockout is embryonic lethal in mice. Moreover, we previously showed AMPKα1 protein is increased in AMPKα2−/− mice, potentially confounding conclusions. Furthermore, the role of intestinal epithelial AMPK in inflammatory responses remains poorly understood. The goals of this study were to determine if AMPK is necessary for intestinal homeostasis and to confirm if intestinal epithelial AMPK is required for protection against colitis in a mouse model.MethodsIntestinal epithelial‐specific deletion of both AMPK catalytic isoforms (AMPKαΔIEC KO) was generated by crossing villin‐Cre recombinase mice with Prkaa1 and Prkaa2 floxed mice (AMPKαfl/fl). Barrier integrity and function were assessed histologically, by 40 kDa FITC‐dextran (FD4) intestinal permeability assay and by agonist stimulation of chloride secretion ex vivo in Ussing chambers. Colitis was induced with 5% dextran sulfate sodium (DSS) in drinking water for 5 days, followed by 3 days of water. Body weight, stool consistency and hemoccult were recorded daily to determine disease activity index scores. Intestinal permeability during colitis was determined by FD4 permeability. Mice were euthanized according to institutional IACUC protocols. Tissues were fixed in 4% paraformaldehyde for imaging or flash frozen for protein and RNA analysis.ResultsUnchallenged AMPKαΔIEC KO mice showed no histologic changes in intestinal integrity, nor any significant change in intestinal permeability or agonist‐stimulated chloride secretion. Mice administered 5% DSS developed severe colitis indicated by dramatic weight loss and increased disease activity index score compared to untreated controls. Colitis induced similar levels of colonic shortening and increased intestinal permeability in both floxed and AMPKαΔIEC KO mice, however AMPK‐regulated pro‐inflammatory gene expression was unchanged compared to untreated controls. Despite the lack of an overt phenotypic difference in AMPKαΔIEC KO mice compared to AMPKαfl/fl mice, we did observe significant differences in protein expression. The tight junction protein claudin 2 was significantly decreased in proximal colon of AMPKαΔIEC KO mice compared to AMPKαfl/fl mice without DSS challenge. Untreated and DSS‐treated AMPKαΔIEC KO mice had decreased levels of the apoptosis markers cleaved caspase 3 in ileum, and PARP in proximal colon respectively, while cleaved caspase 3 was increased in distal colon compared to matched AMPKαfl/fl mice.ConclusionLoss of AMPK alone altered levels of claudin 2 and apoptotic markers in intestinal epithelial cells but did not alter DSS‐induced colitis severity.Support or Funding InformationNIH 2R01DK091281 (DFM)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Xanthohumol prevents dextran sulfate sodium-induced colitis via inhibition of IKKβ/NF-κB signaling in mice.

Xanthohumol (XN), a prenylated chalcone isolated from the hop plant, has been reported to exhibit multiple biological functions including anti-inflammation. However, the pharmacological function of XN on colitis remains unknown. In this study, we investigated the anti-inflammatory effect of synthesized XN and molecular mechanism on dextran sulfate sodium (DSS)-induced experimental colitis. XN attenuated the colitis symptoms along with the prevention of colonic lesions after DSS challenge. XN inhibited the production of pro-inflammatory cytokines, oxidative stress and cyclooxygenase-2 expression in DSS-treated mice. Moreover, XN inhibited the phosphorylation of IκBα, the nuclear translocation of NF-κB subunits and the transcriptional activity of NF-κB in vivo and in vitro. In contrast to XN, isoXN showed much less effects on the kinase activity of IKKβ and IκBα phosphorylation induced by XN in this study, suggesting that an electrophilic carbon center present in XN is critical for the anti-inflammation in colitis, especially inhibition of IKKβ/NF-κB signaling pathway. Consistently, our docking analysis revealed that XN could bind to the active site, presumably at the Cys99 of IKKβ. Taken together, these findings demonstrate a new function of XN to inhibit IKKβ/NF-κB signaling, suggesting XN could be the potential therapeutic agent for the prevention of colitis.

Angiopoietin-like 4 Mediates Colonic Inflammation by Regulating Chemokine Transcript Stability via Tristetraprolin

Many gastrointestinal diseases exhibit a protracted and aggravated inflammatory response that can lead to hypercytokinaemia, culminating in extensive tissue damage. Recently, angiopoietin-like 4 (ANGPTL4) has been implicated in many inflammation-associated diseases. However, how ANGPTL4 regulates colonic inflammation remains unclear. Herein, we show that ANGPTL4 deficiency in mice (ANGPTL4−/−) exacerbated colonic inflammation induced by dextran sulfate sodium (DSS) or stearic acid. Microbiota was similar between the two genotypes prior DSS challenge. A microarray gene expression profile of the colon from DSS-treated ANGPTL4−/− mice was enriched for genes involved in leukocyte migration and infiltration, and showed a close association to inflamed ulcerative colitis (UC), whereas the profile from ANGPTL4+/+ littermates resembled that of non-inflamed UC biopsies. Bone marrow transplantation demonstrates the intrinsic role of colonic ANGPTL4 in regulating leukocyte infiltration during DSS-induced inflammation. Using immortalized human colon epithelial cells, we revealed that the ANGPTL4-mediated upregulation of tristetraprolin expression operates through CREB and NF-κB transcription factors, which in turn, regulates the stability of chemokines. Together, our findings suggest that ANGPTL4 protects against acute colonic inflammation and that its absence exacerbates the severity of inflammation. Our findings emphasize the importance of ANGPTL4 as a novel target for therapy in regulating and attenuating inflammation.