Fucose Ameliorates Tritrichomonas sp.-Associated Illness in Antibiotic-Treated Muc2-/- Mice.

The mucus layer in the intestine plays a critical role in regulation of host-microbe interactions and maintaining homeostasis. Disruptions of the mucus layer due to genetic, environmental, or immune factors may lead to inflammatory bowel diseases (IBD). IBD frequently are accompanied with infections, and therefore are treated with antibiotics. Hence, it is important to evaluate risks of antibiotic treatment in individuals with vulnerable gut barrier and chronic inflammation. Mice with a knockout of the Muc2 gene, encoding the main glycoprotein component of the mucus, demonstrate a close contact of the microbes with the gut epithelium which leads to chronic inflammation resembling IBD. Here we demonstrate that the Muc2-/- mice harboring a gut protozoan infection Tritrichomonas sp. are susceptible to an antibiotic-induced depletion of the bacterial microbiota. Suppression of the protozoan infection with efficient metronidazole dosage or L-fucose administration resulted in amelioration of an illness observed in antibiotic-treated Muc2-/- mice. Fucose is a monosaccharide presented abundantly in gut glycoproteins, including Mucin2, and is known to be involved in host-microbe interactions, in particular in microbe adhesion. We suppose that further investigation of the role of fucose in protozoan adhesion to host cells may be of great value.

Increased Listeria monocytogenes Dissemination and Altered Population Dynamics in Muc2-Deficient Mice.

The mucin Muc2 is a major constituent of the mucus layer that covers the intestinal epithelium and creates a barrier between epithelial cells and luminal commensal or pathogenic microorganisms. The Gram-positive foodborne pathogen Listeria monocytogenes can cause enteritis and also disseminate from the intestine to give rise to systemic disease. L. monocytogenes can bind to intestinal Muc2, but the influence of the Muc2 mucin barrier on L. monocytogenes intestinal colonization and systemic dissemination has not been explored. Here, we used an orogastric L. monocytogenes infection model to investigate the role of Muc2 in host defense against L. monocytogenes Compared to wild-type mice, we found that Muc2-/- mice exhibited heightened susceptibility to orogastric challenge with L. monocytogenes, with higher mortality, elevated colonic pathology, and increased pathogen burdens in both the intestinal tract and distal organs. In contrast, L. monocytogenes burdens were equivalent in wild-type and Muc2-/- animals when the pathogen was administered intraperitoneally, suggesting that systemic immune defects related to Muc2 deficiency do not explain the heightened pathogen dissemination observed in oral infections. Using a barcoded L. monocytogenes library to measure intrahost pathogen population dynamics, we found that Muc2-/- animals had larger pathogen founding population sizes in the intestine and distal sites than observed in wild-type animals. Comparisons of barcode frequencies suggested that the colon becomes the major source for seeding the internal organs in Muc2-/- animals. Together, our findings reveal that Muc2 mucin plays a key role in controlling L. monocytogenes colonization, dissemination, and population dynamics.

Increased intestinal permeability exacerbates sepsis through reduced hepatic SCD-1 activity and dysregulated iron recycling.

Inflammatory bowel disease is associated with changes in the mucosal barrier, increased intestinal permeability, and increased risk of infections and sepsis, but the underlying mechanisms are incompletely understood. Here, we show how continuous translocation of gut microbial components affects iron homeostasis and facilitates susceptibility to inflammation-associated sepsis. A sub-lethal dose of lipopolysaccharide results in higher mortality in Mucin 2 deficient (Muc2-/-) mice, and is associated with elevated circulatory iron load and increased bacterial translocation. Translocation of gut microbial components attenuates hepatic stearoyl CoA desaturase-1 activity, a key enzyme in hepatic de novo lipogenesis. The resulting reduction of hepatic saturated and unsaturated fatty acid levels compromises plasma membrane fluidity of red blood cells, thereby significantly reducing their life span. Inflammation in Muc2-/- mice alters erythrophagocytosis efficiency of splenic macrophages, resulting in an iron-rich milieu that promotes bacterial growth. Our study thus shows that increased intestinal permeability triggers a cascade of events resulting in increased bacterial growth and risk of sepsis.

Eradication of Helicobacter spp. in mucin2-deficient mice.

Infections with Helicobacter spp. are known to have serious effects on rodent health, especially in immunocompromised animals. In this study three approaches were used to eradicate Helicobacter spp. infection in mice with a deficiency in intestinal proteoglycan (mucin2), namely triple oral antibiotic therapy (amoxicillin, clarithromycin and metronidazole), cross-fostering of neonatal pups by surrogate mothers negative for Helicobacter spp., and in vitro fertilization (IVF) with embryo transfer into Helicobacter-free mothers. However, triple antibiotic therapy in mice with mucin2 deficiency was not effective and had negative effects on reproductive performance, and high susceptibility of mucin2-deficient mice to Helicobacter spp. during the first 12 h after birth rendered cross-fostering impossible. Only IVF with embryo transfer was effective in eradicating Helicobacter infection from transgenic mice with mucin2 deficiency.

The goblet cell-derived mediator RELM-ß drives spontaneous colitis in Muc2-deficient mice by promoting commensal microbial dysbiosis.

Intestinal goblet cells are potentially key players in controlling susceptibility to ulcerative colitis (UC). Although impaired mucin (Muc2) production by goblet cells increases microbial stimulation of the colonic mucosa, goblet cells secrete other mediators that may influence or promote UC development. Correspondingly, Muc2-deficient ((-/-)) mice develop spontaneous colitis, concurrent with the dramatic upregulation of the goblet cell mediator, resistin-like molecule-beta (RELM-ß). Testing RELM-ß's role, we generated Muc2(-/-)/Retnlb(-/-) mice, finding that RELM-ß deficiency significantly attenuated colitis development and symptoms compared with Muc2(-/-) mice. RELM-ß expression in Muc2(-/-) mice strongly induced the production/secretion of the antimicrobial lectin RegIIIß, that exerted its microbicidal effect predominantly on Gram-positive Lactobacillus species. Compared with Muc2(-/-)/Retnlb(-/-) mice, this worsened intestinal microbial dysbiosis with a selective loss of colonic Lactobacilli spp. in Muc2(-/-) mice. Orally replenishing Muc2(-/-) mice with murine Lactobacillus spp., but not with a probiotic formulation containing several human Lactobacillus spp. (VSL#3), ameliorated their spontaneous colitis in concert with increased production of short-chain fatty acids. These studies demonstrate that the goblet cell mediator RELM-ß drives colitis in Muc2(-/-) mice by depleting protective commensal microbes. The ability of selective commensal microbial replacement to ameliorate colitis suggests that personalized bacterial therapy may prove beneficial for treatment of UC.

Deficiency of intestinal mucin-2 protects mice from diet-induced fatty liver disease and obesity.

Nonalcoholic fatty liver disease (NAFLD) and obesity are characterized by altered gut microbiota, inflammation, and gut barrier dysfunction. Here, we investigated the role of mucin-2 (Muc2) as the major component of the intestinal mucus layer in the development of fatty liver disease and obesity. We studied experimental fatty liver disease and obesity induced by feeding wild-type and Muc2-knockout mice a high-fat diet (HFD) for 16 wk. Muc2 deficiency protected mice from HFD-induced fatty liver disease and obesity. Compared with wild-type mice, after a 16-wk HFD, Muc2-knockout mice exhibited better glucose homeostasis, reduced inflammation, and upregulated expression of genes involved in lipolysis and fatty acid ß-oxidation in white adipose tissue. Compared with wild-type mice that were fed the HFD as well, Muc2-knockout mice also displayed higher intestinal and plasma levels of IL-22 and higher intestinal levels of the IL-22 target genes Reg3b and Reg3g. Our findings indicate that absence of the intestinal mucus layer activates the mucosal immune system. Higher IL-22 levels protect mice from diet-induced features of the metabolic syndrome.

Mulberry fruit prevents LPS-induced NF-κB/pERK/MAPK signals in macrophages and suppresses acute colitis and colorectal tumorigenesis in mice.

Here, we investigated the impact of mulberry fruit (MBF) extracts on lipopolysaccharide (LPS)-induced inflammatory responses in RAW 264.7 macrophages, and the therapeutic efficacy of MBF diet in mice with dextran sulfate sodium (DSS)-induced acute colitis and MUC2(-/-) mice with colorectal cancer. In vitro, LPS-induced nitric oxide (NO) production was significantly inhibited by MBF extracts via suppressing the expression of proinflammatory molecules, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1 beta (IL-ß) and IL-6. Particularly, a dose-dependent inhibition on LPS-induced inflammatory responses was observed following treatment with MBF dichloromethane extract (MBF-DE), in which linoleic acid and ethyl linolenate were identified as two active compounds. Moreover, we elucidated that MBF-DE attenuated LPS-induced inflammatory responses by blocking activation of both NF-κB/p65 and pERK/MAPK pathways. In vivo, DSS-induced acute colitis was significantly ameliorated in MBF-fed mice as gauged by weight loss, colon morphology and histological damage. In addition, MBF-fed MUC2(-/-) mice displayed significant decrease in intestinal tumor and inflammation incidence compared to control diet-fed group. Overall, our results demonstrated that MBF suppressed the development of intestinal inflammation and tumorgenesis both in vitro and in vivo, and supports the potential of MBF as a therapeutic functional food for testing in human clinical trials.

CD103+ CD11b+ Dendritic Cells Induce Th17 T Cells in Muc2-Deficient Mice with Extensively Spread Colitis.

Mucus alterations are a feature of ulcerative colitis (UC) and can drive inflammation by compromising the mucosal barrier to luminal bacteria. The exact pathogenesis of UC remains unclear, but CD4+ T cells reacting to commensal antigens appear to contribute to pathology. Given the unique capacity of dendritic cells (DCs) to activate naive T cells, colon DCs may activate pathogenic T cells and contribute to disease. Using Muc2-/- mice, which lack a functional mucus barrier and develop spontaneous colitis, we show that colitic animals have reduced colon CD103+ CD11b- DCs and increased CD103- CD11b+ phagocytes. Moreover, changes in colonic DC subsets and distinct cytokine patterns distinguish mice with distally localized colitis from mice with colitis spread proximally. Specifically, mice with proximally spread, but not distally contained, colitis have increased IL-1ß, IL-6, IL-17, TNFα, and IFNγ combined with decreased IL-10 in the distal colon. These individuals also have increased numbers of CD103+ CD11b+ DCs in the distal colon. CD103+ CD11b+ DCs isolated from colitic but not noncolitic mice induced robust differentiation of Th17 cells but not Th1 cells ex vivo. In contrast, CD103- CD11b+ DCs from colitic Muc2-/- mice induced Th17 as well as Th1 differentiation. Thus, the local environment influences the capacity of intestinal DC subsets to induce T cell proliferation and differentiation, with CD103+ CD11b+ DCs inducing IL-17-producing T cells being a key feature of extensively spread colitis.

Spontaneous colitis in Muc2-deficient mice reflects clinical and cellular features of active ulcerative colitis.

BACKGROUND: The colonic mucus layer plays a critical role in intestinal homeostasis by limiting contact between luminal bacteria and the mucosal immune system. A defective mucus barrier in animal models allows bacterial contact with the intestinal epithelium and results in spontaneous colitis. A defective mucus barrier is also a key feature of active ulcerative colitis (UC). Alterations in the immune compartment due to intestinal bacterial breach in mice lacking the colon mucus barrier have not been characterized and correlated to active UC. AIMS: To characterize alterations in the immune compartment due to intestinal bacterial breach in Muc2-/- mice, which lack the colon mucus barrier, and correlate the findings to active UC. METHODS: Bacterial contact with colon epithelium and penetration into colon tissue was examined in Muc2-/- mice and colon biopsies from patients with active UC using fluorescence microscopy and qPCR. Neutrophils, lymphocytes, CD103+ dendritic cell subsets and macrophages in colon from Muc2-/- mice and biopsies from UC patients were quantitated by flow cytometry. RESULTS: Inflamed UC patients and Muc2-/- mice had bacteria in contact with the colon epithelium. Bacterial rRNA was present in colonic mucosa in humans and Muc2-/- mice and in the draining lymph nodes of mice. Inflamed Muc2-/- mice and UC patients had elevated colon neutrophils, T cells and macrophages while a reduced frequency of CD103+ DCs was present in the inflamed colon of both mice and humans. CONCLUSIONS: The parallel features of the colon immune cell compartment in Muc2-/- mice and UC patients supports the usefulness of this model to understand the early phase of spontaneous colitis and will provide insight into novel strategies to treat UC.

High beta-palmitate fat controls the intestinal inflammatory response and limits intestinal damage in mucin Muc2 deficient mice.

BACKGROUND: Palmitic-acid esterified to the sn-1,3 positions of the glycerol backbone (alpha, alpha'-palmitate), the predominant palmitate conformation in regular infant formula fat, is poorly absorbed and might cause abdominal discomfort. In contrast, palmitic-acid esterified to the sn-2 position (beta-palmitate), the main palmitate conformation in human milk fat, is well absorbed. The aim of the present study was to examine the influence of high alpha, alpha'-palmitate fat (HAPF) diet and high beta-palmitate fat (HBPF) diet on colitis development in Muc2 deficient (Muc2(-/-)) mice, a well-described animal model for spontaneous enterocolitis due to the lack of a protective mucus layer. METHODS: Muc2(-/-) mice received AIN-93G reference diet, HAPF diet or HBPF diet for 5 weeks after weaning. Clinical symptoms, intestinal morphology and inflammation in the distal colon were analyzed. RESULTS: Both HBPF diet and AIN-93G diet limited the extent of intestinal erosions and morphological damage in Muc2(-/-) mice compared with HAPF diet. In addition, the immunosuppressive regulatory T (Treg) cell response as demonstrated by the up-regulation of Foxp3, Tgfb1 and Ebi3 gene expression levels was enhanced by HBPF diet compared with AIN-93G and HAPF diets. HBPF diet also increased the gene expression of Pparg and enzymatic antioxidants (Sod1, Sod3 and Gpx1), genes all reported to be involved in promoting an immunosuppressive Treg cell response and to protect against colitis. CONCLUSIONS: This study shows for the first time that HBPF diet limits the intestinal mucosal damage and controls the inflammatory response in Muc2(-/-) mice by inducing an immunosuppressive Treg cell response.

Deficiency of intestinal mucin-2 ameliorates experimental alcoholic liver disease in mice.

UNLABELLED: The intestinal mucus layer protects the epithelium from noxious agents, viruses, and pathogenic bacteria present in the gastrointestinal tract. It is composed of mucins, predominantly mucin (Muc) 2, secreted by goblet cells of the intestine. Experimental alcoholic liver disease requires translocation of bacterial products across the intestinal barrier into the systemic circulation, which induces an inflammatory response in the liver and contributes to steatohepatitis. We investigated the roles of the intestinal mucus layer, and in particular Muc2, in development of experimental alcohol-associated liver disease in mice. We studied experimental alcohol-induced liver disease, induced by the Tsukamoto-French method (which involves continuous intragastric feeding of an isocaloric diet or alcohol) in wild-type and Muc2(-/-) mice. Muc2(-/-) mice showed less alcohol-induced liver injury and steatosis than developed in wild-type mice. Most notably, Muc2(-/-) mice had significantly lower plasma levels of lipopolysaccharide than wild-type mice after alcohol feeding. In contrast to wild-type mice, Muc2(-/-) mice were protected from alcohol-associated microbiome changes that are dependent on intestinal mucins. The antimicrobial proteins regenerating islet-derived 3 beta and gamma were expressed at significantly higher levels in the jejunum of Muc2(-/-) mice fed the isocaloric diet or alcohol compared with wild-type mice. Consequently, Muc2(-/-) mice showed increased killing of commensal bacteria and prevented intestinal bacterial overgrowth. CONCLUSION: Muc2(-/-) mice are protected from intestinal bacterial overgrowth and dysbiosis in response to alcohol feeding. Subsequently, lower amounts of bacterial products such as endotoxin translocate into the systemic circulation, decreasing liver disease.

Entamoeba histolytica exacerbates epithelial tight junction permeability and proinflammatory responses in Muc2(-/-) mice.

Human mucin-2 (MUC-2) is the first line of innate host defense in preventing pathogen-induced epithelial injury. Entamoeba histolytica (Eh) colonizes the mucus layer by binding of the parasite's surface galactose lectin to galactose and N-acetyl-d-galactosamine residues on colonic MUC-2, preventing parasite contact-dependent cytolysis of epithelial cells. We quantified early innate responses to Eh in wild-type and MUC-2-deficient mice (Muc2(-/-)) using closed colonic loops. Eh infection in wild-type but not Muc2(-/-) mice induced a time-dependent increase in (3)H-labeled mucin and nonmucin glycoprotein secretions. Immunohistochemical staining revealed intense MUC-2 secretion, which formed a thick, protective mucus plug overlying the surface epithelium, entrapping Eh. In Muc2(-/-) mice, Eh induced a pronounced time-dependent secretory exudate with increased gross pathology scores and serum albumin leakage. Colonic pathology, secretory responses, and increased proinflammatory cytokine secretions of TNF-α, IFN-γ, and IL-13 correlated with altered expression of the tight junction proteins claudin-2, occludin, and ZO-1. We identified the putative Eh virulence factor that elicits the proinflammatory responses and alters tight junction permeability as Eh cysteine protease A5 (EhCP-A5). The present findings demonstrate that colonic mucins confer both luminal and epithelial barrier functions and that, in the absence of MUC-2, mice are more susceptible to Eh-induced secretory and proinflammatory responses mediated by EhCP-A5.

Mucin Muc2 deficiency and weaning influences the expression of the innate defense genes Reg3ß, Reg3γ and angiogenin-4.

BACKGROUND: Mucin Muc2 is the structural component of the intestinal mucus layer. Absence of Muc2 leads to loss of this layer allowing direct bacterial-epithelial interactions. We hypothesized that absence of the mucus layer leads to increased expression of innate defense peptides. Specifically, we aimed to study the consequence of Muc2 deficiency (Muc2(-/-)) on the expression of regenerating islet-derived protein 3 beta (Reg3ß), regenerating islet-derived protein 3 gamma (Reg3γ), and angiogenin-4 (Ang4) in the intestine shortly before and after weaning. METHODS: Intestinal tissues of Muc2(-/-) and wild-type (WT) mice were collected at postnatal day 14 (P14, i.e. pre-weaning) and P28 (i.e. post-weaning). Reg3ß, Reg3γ, and Ang4 expression was studied by quantitative real-time PCR, Western-blot, in situ hybridization, and immunohistochemistry. RESULTS: Reg3ß and Reg3γ were expressed by diverging epithelial cell types; namely enterocytes, Paneth cells, and goblet cells. Additionally, Ang4 expression was confined to Paneth cells and goblet cells. Expression of Reg3ß, Reg3γ, and Ang4 differed between WT and Muc2(-/-) mice before and after weaning. Interestingly, absence of Muc2 strongly increased Reg3ß and Reg3γ expression in the small intestine and colon. Finally, morphological signs of colitis were only observed in the distal colon of Muc2(-/-) mice at P28, where and when expression levels of Reg3ß, Reg3γ, and Ang4 were the lowest. CONCLUSIONS: Expression of Reg3 proteins and Ang4 by goblet cells point to an important role for goblet cells in innate defense. Absence of Muc2 results in up-regulation of Reg3ß and Reg3γ expression, suggesting altered bacterial-epithelial signaling and an innate defense response in Muc2(-/-) mice. The inverse correlation between colitis development and Reg3ß, Reg3γ, and Ang4 expression levels might point toward a role for these innate defense peptides in regulating intestinal inflammation.

Mucin depleted foci, colonic preneoplastic lesions lacking Muc2, show up-regulation of Tlr2 but not bacterial infiltration.

Mucin depleted foci (MDF) are precancerous lesions of the colon in carcinogen-treated rodents and humans at high risk. Since MDF show signs of inflammation we hypothesized that the defective mucous production would expose them to the risk of being penetrated by intestinal bacteria, which can be sensed by Toll-like receptors (Tlrs) and activate inflammatory pathways. To verify this hypothesis we tested the expression of 84 genes coding for Tlrs and associated pathways using RT-qPCR in MDF (n = 7) from 1,2-dimethylhydrazine (DMH)-treated rats. Among the 84 tested genes, 26 were differentially expressed in MDF with 5 genes significantly up-regulated and 21 down-regulated when compared to the normal mucosa. Tlr2, as well as other downstream genes (Map4k4, Hspd1, Irak1, Ube2n), was significantly up-regulated. Among the genes regulating the NFkB pathway, only Map4k4 was significantly up-regulated, while 19 genes were not varied and 6 were down-regulated. Tlr2 protein was weakly expressed both in normal mucosa and MDF. To determine whether inflammation observed in MDF could be caused by bacteria contacting or infiltrating crypts, we performed fluorescence in situ hybridization (FISH) experiments with a rRNA universal bacterial probe. None of the 21 MDF tested, showed bacteria inside the crypts, while among the colonic tumors (n = 15), only one had very few bacteria on the surface and on the surrounding normal mucosa. In conclusion, the up-regulation of Tlr2 in MDF, suggests a link between this receptor and carcinogenesis, possibly related to a defective barrier function of these lesions. The data of FISH experiments do not support the hypothesis that inflammation in MDF and tumors is stimulated by bacterial infiltration.

Colitis development during the suckling-weaning transition in mucin Muc2-deficient mice.

The mucin Muc2 is the structural component of the colonic mucus layer. Adult Muc2 knockout (Muc2(-/-)) mice suffer from severe colitis. We hypothesized that Muc2 deficiency induces inflammation before weaning of mother's milk [postnatal day (P) 14] with aggravation of colitis after weaning (P28). Muc2(-/-) and wild-type mice were killed at embryonic day 18.5 and P1.5, P7.5, P14, P21, and P28. Colonic morphology, influx of T cells, and goblet cell-specific protein expression was investigated by (immuno)histochemistry. Cytokine and Toll-like receptor (TLR) profiles in the colon were analyzed by quantitative RT-PCR. Muc2(-/-) mice showed an increased and persistent influx of Cd3ε-positive T cells in the colonic mucosa as of P1.5. This was accompanied by mucosal damage at P28 in the distal colon but not in the proximal colon. At P14, the proinflammatory immune response [i.e., increased interleukin (IL)-12 p35, IL-12 p40, and tumor necrosis factor-α, expression] in the distal colon of Muc2(-/-) mice presented with an immune suppressive response [i.e., increased Foxp3, transforming growth factor (TGF)-ß1, IL-10, and Ebi3 expression]. In contrast, at P28, a proinflammatory response remained in the distal colon, whereas the immune suppressive response (i.e., Foxp3 and TGF-ß1 expression) declined. The proximal colon of Muc2(-/-) mice did not show morphological damage and was dominated by an immune suppressive response at P14 and P28. Interestingly, changes in expression of TLRs and TLR-related molecules were observed in the distal colon at P14 and P28 and in the proximal colon only at P28. Colitis in Muc2(-/-) mice is limited before weaning by immune suppressive responses and exacerbates in the distal colon after weaning because of the decline in the immune suppressive response.

Muc-2-deficient mice display a sex-specific, COX-2-related impairment of gastric mucosal repair.

Mucus is known to contribute significantly to the prevention and repair of mucosal damage throughout the gastrointestinal tract. Although not normally expressed in the stomach, mucin-2 (MUC-2, encoded by the MUC2 gene) is expressed in certain disease states. The aim of this study was to determine in a mouse model whether the absence of Muc-2 would result in impaired susceptibility to and healing of gastric mucosal injury. Acute gastric damage was induced in mice deficient in Muc-2 and in wild-type controls, through oral administration of indomethacin. Chronic gastric ulcers were induced by serosal application of acetic acid. The extent of injury and the extent of healing of the damage over time were examined in both models. Indomethacin administration caused similar levels of gastric damage in Muc-2-deficient and wild-type mice, but the erosions healed more slowly in the former. Acetic acid-induced gastric ulcers were initially similar in size in Muc-2-deficient and wild-type mice of both sexes, but ulcer healing was significantly impaired in male Muc-2-deficient mice. Induction of cyclooxygenase-2 in the stomach, in response to indomethacin- or acetic acid-induced ulceration, was significantly reduced in male Muc-2-deficient mice. This phenomenon, and the sex specificity, was also apparent in bone marrow-derived macrophages stimulated with endotoxin. These results demonstrate a marked impairment of gastric mucosal repair in male Muc-2-deficient mice that may be related to an insufficient induction of cyclooxygenase-2, an enzyme known to contribute to mucosal repair.

Mucin gene deficiency in mice impairs host resistance to an enteric parasitic infection.

BACKGROUND & AIMS: Hyperplasia of mucin-secreting intestinal goblet cells accompanies a number of enteric infections, including infections by nematode parasites. Nevertheless, the precise role of mucins in host defense in nematode infection is not known. We investigated the role of the mucin (Muc2) in worm expulsion and host immunity in a model of nematode infection. METHODS: Resistant (BALB/c, C57BL/6), susceptible (AKR), and Muc2-deficient mouse strains were infected with the nematode, Trichuris muris, and worm expulsion, energy status of the whipworms, changes in mucus/mucins, and inflammatory and immune responses were investigated after infection. RESULTS: The increase in Muc2 production, observed exclusively in resistant mice, correlated with worm expulsion. Moreover, expulsion of the worms from the intestine was significantly delayed in the Muc2-deficient mice. Although a marked impairment in the development of periodic acid Schiff (PAS)-stained intestinal goblet cells was observed in Muc2-deficient mice, as infection progressed a significant increase in the number of PAS-positive goblet cells was observed in these mice. Surprisingly, an increase in Muc5ac, a mucin normally expressed in the airways and stomach, was observed after infection of only the resistant animals. Overall, the mucus barrier in the resistant mice was less permeable than that of susceptible mice. Furthermore, the worms isolated from the resistant mice had a lower energy status. CONCLUSIONS: Mucins are an important component of innate defense in enteric infection; this is the first demonstration of the important functional contribution of mucins to host protection from nematode infection.

Inhibitory effects of high temperature- and pressure-treated garlic on formation of 1,2-dimethylhydrazine-induced mucin-depleted foci and O(6)-methylguanine DNA adducts in the rat colorectum.

High temperature- and pressure-treated garlic (HTPG) has been reported to have enhanced antioxidative and cytotoxic activities. However, there have been no reports on chemopreventive effects using animal cancer models. This study first examined the modifying effects of HTPG on 1,2-dimethylhydrazine (DMH)-induced mucin-depleted foci (MDF) and aberrant crypt foci (ACF), preneoplastic lesions in the rat colorectum. Male F344 rats (5 weeks old) were fed basal diet, or experimental diets containing 1% or 3% HTPG for 5 weeks. One week later, all rats were injected s.c.with DMH (40 mg/kg, once weekly for 2 weeks). At 10 weeks of age, all the rats were sacrificed, and the colorectum was evaluated for MDF and ACF. In rats given DMH and 3% HTPG, the numbers of MDF were decreased significantly as compared with those of rats given DMH alone (p< 0.01), and the numbers of ACF showed a tendency to decrease, although not significantly. Next, the effects of HTPG on the formation of DMH-induced O6-methylguanine (O6-MeG) DNA adducts in rats were studied. Male F344 rats (5 weeks old) were fed the basal diet or 10% HTPG diet for 5 weeks. All rats were injected i.p. once with 40 mg/kg DMH at the end of week 5. The animals were sacrificed 6 hours after DMH injection to analyze the O6-MeG DNA adducts in the colorectal mucosa and liver. Dietary administration of HTPG significantly reduced the adduct levels in the colorectal mucosa and liver, compared with the controls (both p< 0.01). The activities of some detoxification enzymes in the liver of DMH-treated rats were also measured. HTPG significantly reduced the activity of cytochrome P450 (CYP) 2E1, known to be responsible for activation of DMH in rat liver (p< 0.05). In contrast, HTPG significantly enhanced the activities of phase 2 enzymes, quinone reductase (QR) and glutathione S-transferase (GST), in rat liver (both p< 0.05). These results suggested that HTPG might have chemopreventive effects against colon carcinogenesis, at least in the initiation stage.