Paneth cells: their role in innate immunity and inflammatory disease

Roles of Autophagy-Related Genes in the Pathogenesis of Inflammatory Bowel Disease

Autophagy is an intracellular catabolic process that is essential for a variety of cellular responses. Due to its role in the maintenance of biological homeostasis in conditions of stress, dysregulation or disruption of autophagy may be linked to human diseases such as inflammatory bowel disease (IBD). IBD is a complicated inflammatory colitis disorder; Crohn’s disease and ulcerative colitis are the principal types. Genetic studies have shown the clinical relevance of several autophagy-related genes (ATGs) in the pathogenesis of IBD. Additionally, recent studies using conditional knockout mice have led to a comprehensive understanding of ATGs that affect intestinal inflammation, Paneth cell abnormality and enteric pathogenic infection during colitis. In this review, we discuss the various ATGs involved in macroautophagy and selective autophagy, including ATG16L1, IRGM, LRRK2, ATG7, p62, optineurin and TFEB in the maintenance of intestinal homeostasis. Although advances have been made regarding the involvement of ATGs in maintaining intestinal homeostasis, determining the precise contribution of autophagy has remained elusive. Recent efforts based on direct targeting of ATGs and autophagy will further facilitate the development of new therapeutic opportunities for IBD.

Extensive Paneth cell metaplasia in an ovarian Krukenberg tumor: report of an unusual case and literature review

Paneth cells are classified as secretory cells which are normally found in the cecum and ascending colon. Their presence in other parts of the gastrointestinal tract is regarded as abnormal and indicates metaplasia. Paneth cells may also be rarely found in gastrointestinal, biliary and prostatic tumors. The presence of Paneth cells in ovarian Krukenberg tumors is rare and to the best of our knowledge is restricted to metastatic appendiceal goblet cells tumors. We report a rare case of unilateral metastatic gastric carcinoma to the ovary in a 23-year-old female. This tumor showed unusual extensive Paneth cells metaplasia with classical signet ring cell morphology.

Innate and adaptive immunity in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most frequent and devastating gastrointestinal disease of premature infants. Although the precise mechanisms are not fully understood, NEC is thought to develop following a combination of prematurity, formula feeding, and adverse microbial colonization. Within the last decade, studies increasingly support an important role of a heightened mucosal immune response initiating a pro-inflammatory signaling cascade, which can lead to the disruption of the intestinal epithelium and translocation of pathogenic species. In this review, we first describe the cellular composition of the intestinal epithelium and its critical role in maintaining epithelial integrity. We then discuss cell signaling during NEC, specifically, toll-like receptors and nucleotide oligomerization domain-like receptors. We further review cytokines and cellular components that characterize the innate and adaptive immune systems and how they interact to support or modulate NEC development.

Detection of α-defensin in eosinophils in helminth-infected mouse model

α-defensin is a potent antimicrobial peptide secreted from intestinal mucosal epithelial cells, such as Paneth cells, and affects not only bacteria but also parasites and fungi. Recently, human eosinophils have also been shown to produce α-defensin, but no studies have been done on other animals. In this study, we attempted to detect α-defensin protein in mouse eosinophils infiltrating the intestinal mucosa during a helminth infection using Zamboni fixation and immunohistochemistry. Most of the eosinophils infiltrating the intestinal mucosa during helminth infection were positive for α-defensin. The expression level of α-defensin mRNA was 50 fold that in the control. Meanwhile, the number of Paneth cells was doubled, and their α-defensin fluorescence intensity was increased. These results suggested that eosinophils are also important producers of α-defensin, such as Paneth cells in mice, and that α-defensin produced from eosinophils might be involved in defensive mechanisms against helminths. Moreover, the experimental system used in this study is a good model to study the generation of α-defensin by eosinophils.

Rutin and Its Combination With Inulin Attenuate Gut Dysbiosis, the Inflammatory Status and Endoplasmic Reticulum Stress in Paneth Cells of Obese Mice Induced by High-Fat Diet

Gut dysbiosis induced by high fat diet (HF) or obesity is a predisposing factor to develop diverse inflammatory diseases. Polyphenols and fibers, often eaten together, have been reported to have prebiotic actions, but their health promoting benefits still need to be further characterized and defined. This study attempted to understand how polyphenol rutin and polysaccharide inulin influence intestinal health in mouse model fed a HF (60 kcal%) diet. A total of 48 C57BL/6J mice were divided into four groups fed with a low fat (10% kcal%) control diet (LC), a high fat control diet (HC), a high-fat diet supplemented with rutin (HR), or a high-fat diet supplemented rutin and inulin (HRI) for 20 weeks. Rutin supplementation reduced the HF diet-induced increase of Firmicutes/Bacteroidetes (F/B) ratio, Deferribacteraceae population and plasma lipopolysaccharide (LPS) (p < 0.05); ameliorated inflammation as indicated by the decreased circulating inflammatory cytokines (p < 0.05) and the reduced expressions of intestinal inflammatory mediators (p < 0.05); and attenuated the endoplasmic reticulum (ER) stress in Paneth cells as indicated by the decreased expressions of the ER markers (p < 0.05). Compared to the rutin supplementation alone, the co-administration of rutin with inulin improved the utilization of rutin as indicated by its decreased excretion, suppressed a number of harmful bacteria including Deferribacteraceae and Desulfovibrionaceae (p < 0.05), and further reduced the expression of the key inflammatory cytokine TNF-α and increased the production of butyrate, despite the supplementation of inulin reversed the decrease of body weight induced by rutin supplementation due to an increased food intake. Taken together, our data demonstrated that rutin supplementation ameliorated the inflammatory status and ER stress in Paneth cells under a HF-induced obese state, and its co-administration with inulin further mitigated the inflammatory status, indicating the potential to combine polyphenol rutin and the polysaccharide inulin as a dietary strategy to ameliorate gut dysbiosis, to improve inflammatory status and thereby to reduce medical disorders associated with HF-induced obesity.

Genome-wide DNA Methylation in Treatment-naïve Ulcerative Colitis

BACKGROUND AND AIMS

The aim of this study was to investigate the genome-wide DNA methylation status in treatment-naïve ulcerative colitis [UC], and to explore the relationship between DNA methylation patterns and gene expression levels in tissue biopsies from a well-stratified treatment-naïve UC patient group.

METHODS

Mucosal biopsies from treatment-naïve patients [n = 10], and a healthy control group [n = 11] underwent genome-wide DNA bisulfite sequencing. Principal component analysis [PCA] and diverse statistical methods were applied to obtain a dataset of differentially methylated genes. DNA methylation annotation was investigated using the UCSC Genome Browser. Gene set enrichments were obtained using the Kyoto Encyclopaedia of Genes and Genomes [KEGG] and PANTHER.

RESULTS

Of all significantly differentially expressed genes [DEGs], 25% correlated with DNA methylation patterns; 30% of these genes were methylated at CpG sites near their transcription start site [TSS]. Hyper-methylation was observed for genes involved in homeostasis and defence, whereas hypo-methylation was observed for genes playing a role in immune response [i.e. chemokines and interleukins]. Of the differentially DNA methylated genes, 25 were identified as inflammatory bowel disease [IBD] susceptibility genes. Four genes [DEFFA6, REG1B, BTNL3, OLFM4] showed DNA methylation in the absence of known CpG islands.

CONCLUSIONS

Genome-wide DNA methylation analysis revealed distinctive functional patterns for hyper-and hypo-methylation in treatment-naïve UC. These distinct patterns could be of importance in the development and pathogenesis of UC. Further investigation of DNA methylation patterns may be useful in the development of the targeting of epigenetic processes, and may allow new treatment and target strategies for UC patients.

Two-photon microscopy of Paneth cells in the small intestine of live mice

Paneth cells are one of the principal epithelial cell types in the small intestine, located at the base of intestinal crypts. Paneth cells play key roles in intestinal host-microbe homeostasis via granule secretion, and their dysfunction is implicated in pathogenesis of several diseases including Crohn’s disease. Despite their physiological importance, study of Paneth cells has been hampered by the limited accessibility and lack of labeling methods. In this study, we developed a simple in vivo imaging method of Paneth cells in the intact mouse small intestine by using moxifloxacin and two-photon microscopy (TPM). Moxifloxacin, an FDA-approved antibiotic, was used for labeling cells and its fluorescence was strongly observed in Paneth cell granules by TPM. Moxifloxacin labeling of Paneth cell granules was confirmed by molecular counterstaining. Comparison of Paneth cells in wild type, genetically obese (ob/ob), and germ-free (GF) mice showed different granule distribution. Furthermore, Paneth cell degranulation was observed in vivo. Our study suggests that TPM with moxifloxacin labeling can serve as a useful tool for studying Paneth cell biology and related diseases.

Evolutionary conservation of the antimicrobial function of mucus: a first defence against infection

Mucus layers often provide a unique and multi-functional hydrogel interface between the epithelial cells of organisms and their external environment. Mucus has exceptional properties including elasticity, changeable rheology and an ability to self-repair by re-annealing, and is therefore an ideal medium for trapping and immobilising pathogens and serving as a barrier to microbial infection. The ability to produce a functional surface mucosa was an important evolutionary step, which evolved first in the Cnidaria, which includes corals, and the Ctenophora. This allowed the exclusion of non-commensal microbes and the subsequent development of the mucus-lined digestive cavity seen in higher metazoans. The fundamental architecture of the constituent glycoprotein mucins is also evolutionarily conserved. Although an understanding of the biochemical interactions between bacteria and the mucus layer are important to the goal of developing new antimicrobial strategies, they remain relatively poorly understood. This review summarises the physicochemical properties and evolutionary importance of mucus, which make it so successful in the prevention of bacterial infection. In addition, the strategies developed by bacteria to counteract the mucus layer are also explored.

Cytokine Tuning of Intestinal Epithelial Function

The intestine serves as both our largest single barrier to the external environment and the host of more immune cells than any other location in our bodies. Separating these potential combatants is a single layer of dynamic epithelium composed of heterogeneous epithelial subtypes, each uniquely adapted to carry out a subset of the intestine’s diverse functions. In addition to its obvious role in digestion, the intestinal epithelium is responsible for a wide array of critical tasks, including maintaining barrier integrity, preventing invasion by microbial commensals and pathogens, and modulating the intestinal immune system. Communication between these epithelial cells and resident immune cells is crucial for maintaining homeostasis and coordinating appropriate responses to disease and can occur through cell-to-cell contact or by the release or recognition of soluble mediators. The objective of this review is to highlight recent literature illuminating how cytokines and chemokines, both those made by and acting on the intestinal epithelium, orchestrate many of the diverse functions of the intestinal epithelium and its interactions with immune cells in health and disease. Areas of focus include cytokine control of intestinal epithelial proliferation, cell death, and barrier permeability. In addition, the modulation of epithelial-derived cytokines and chemokines by factors such as interactions with stromal and immune cells, pathogen and commensal exposure, and diet will be discussed.

Gastrointestinal mucosal development and injury in premature lambs supported by the artificial placenta

BACKGROUND

An Artificial Placenta (AP) utilizing extracorporeal life support (ECLS) could revolutionize care of extremely premature newborns, but its effects on gastrointestinal morphology and injury need investigation.

METHODS

Lambs (116-121days GA, term=145; n=5) were delivered by C-section, cannulated for ECLS, had total parenteral nutrition (TPN) provided, and were supported for 7days before euthanasia. Early and Late Tissue Controls (ETC, n=5 and LTC, n=5) delivered at 115-121days and 125-131days, respectively, were immediately sacrificed. Standardized jejunal samples were formalin-fixed for histology. Crypt depth (CD), villus height (VH), and VH:CD ratios were measured. Measurements also included enterocyte proliferation (Ki-67), Paneth cell count (Lysozyme), and injury scores (H&E). ANOVA and Chi Square were used with p<0.05 considered significant.

RESULTS

CD, VH, and VH:CD were similar between groups (p>0.05). AP demonstrated more enterocyte proliferation (95.7±21.8) than ETC (49.4±23.4; p=0.003) and LTC (66.1+11.8; p=0.04), and more Paneth cells (81.7±17.5) than ETC (41.6±7.0; p=0.0005) and LTC (40.7±8.2, p=0.0004). Presence of epithelial injury and congestion in the bowel of all groups were not statistically different. No villus atrophy or inflammation was present in any group.

CONCLUSIONS

This suggests preserved small bowel mucosal architecture, high cellular turnover, and minimal evidence of injury.

STUDY TYPE

Research paper/therapeutic potential.

LEVEL OF EVIDENCE

N/A.

Impact of Paneth Cell Autophagy on Inflammatory Bowel Disease

Intestinal mucosal barrier, mainly consisting of the mucus layer and epithelium, functions in absorbing nutrition as well as prevention of the invasion of pathogenic microorganisms. Paneth cell, an important component of mucosal barrier, plays a vital role in maintaining the intestinal homeostasis by producing antimicrobial materials and controlling the host-commensal balance. Current evidence shows that the dysfunction of intestinal mucosal barrier, especially Paneth cell, participates in the onset and progression of inflammatory bowel disease (IBD). Autophagy, a cellular stress response, involves various physiological processes, such as secretion of proteins, production of antimicrobial peptides, and degradation of aberrant organelles or proteins. In the recent years, the roles of autophagy in the pathogenesis of IBD have been increasingly studied. Here in this review, we mainly focus on describing the roles of Paneth cell autophagy in IBD as well as several popular autophagy-related genetic variants in Penath cell and the related therapeutic strategies against IBD.

The ubiquitin ligase ITCH coordinates small intestinal epithelial homeostasis by modulating cell proliferation, differentiation, and migration

Maintenance of the intestinal mucosa is driven by local signals that coordinate epithelial proliferation, differentiation, and turnover in order to separate antigenic luminal contents from the host's immune system. Breaches in this barrier promote gastrointestinal pathologies ranging from inflammatory bowel disease to cancer. The ubiquitin ligase ITCH is known to regulate immune responses, and loss of function of ITCH has been associated with gastrointestinal inflammatory disorders, particularly in the colon. However, the small intestine appears to be spared from this pathology. Here we explored the physiological mechanism that underlies the preservation of mucosal homeostasis in the small intestine in mice lacking ITCH (Itch^a18H/a18H). Histological analysis of the small intestines from young adult mice revealed architectural changes in animals deficient for ITCH, including villus blunting with cell crowding, crypt expansion, and thickening of the muscularis propria relative to age-matched mice sufficient for ITCH. These differences were more prominent in the distal part of the small intestine and were not dependent upon lymphoid cells. Underlying the observed changes in the epithelium were expansion of the Ki67⁺ proliferating transit amplifying progenitor population and increased numbers of terminally differentiated mucus-secreting goblet and anti-microbial producing Paneth cells, which are both important in controlling local inflammation in the small intestine and are known to be dysregulated in inflammatory bowel disease. Homeostasis in the small intestine of Itch^a18H/a18H animals was maintained by increased cell turnover, including accelerated migration of epithelial cells along the crypt-villus axis and increased apoptosis of epithelial cells at the crypt-villus junction. Consistent with this enhanced turnover, Itch^a18H/a18H mice carrying the Min mutation (Itch^a18H/a18H; Apc^Min/+) displayed a 76% reduction in tumor burden as compared to Apc^Min/+ littermates with normal levels of ITCH. These findings highlight the role of ITCH as an important modulator of intestinal epithelial homeostasis.

Effects of chestnut tannins on intestinal morphology, barrier function, pro-inflammatory cytokine expression, microflora and antioxidant capacity in heat-stressed broilers

A study was conducted to evaluate the effects of chestnut tannins (CT) on intestinal morphology, barrier function, pro-inflammatory cytokine expression, microflora and antioxidant capacity in heat-stressed broilers. Four hundred 28-day-old male Ross 308 broilers were randomly assigned into four groups, with 10 replicates per group and 10 broilers per replicate. The broilers in the normal (NOR) group were kept at 22 ± 1°C and fed the basal diet, and each of the other three groups were treated with cyclic heat (33 ± 1°C from 0800 to 1800 and 22 ± 1°C from 1800 to 0800) and fed the basal diet with 0 (HT), 1 (CT1) or 2 (CT2) g of CT/kg of diet. The experiment lasted for 14 days. Compared with the HT group, broilers in the NOR and CT2 groups had higher (p < .05) average daily gain and villus height in the jejunum and lower serum d-lactate (p < .001) and diamine oxidase (p < .01) levels. The addition of 2 g CT/kg of diet increased the total antioxidant capacity (p < .001) and superoxide dismutase activities (p < .05) and zonula occludens-1 mRNA expression level (p < .05) and decreased the malondialdehyde concentration (p < .01) and mRNA expression levels of interleukin-6 (p < .001) and nuclear factor kappa B (p < .001) in the jejunal mucosa of heat-stressed broilers. The populations of Escherichia coli and Clostridium in the jejunum (p < .01) and caecum (p < .05) of broilers in the HT group were higher than those in the NOR and CT2 groups. In conclusion, the addition of 2 g CT/kg of diet seemed to be a feasible means of alleviating the negative effects of heat stress on the growth performance and intestinal function of broilers.

Changes in protein serum levels during stem cell transplantation

BACKGROUND

GvHD is one of the major complication after stem cell transplantation affecting transplant-related mortality. Throughout the last years, many serum proteins were been proposed as possible biomarkers for GvHD.

AIMS

We studied the trend of five of the most studied serum proteins to evaluate whether a correlation exists between proteins concentration and post-HSCT outcomes.

MATERIALS AND METHODS

We measured serum concentration of REG3α, ST2, B-cell activating factor (BAFF), CXCL9 and elafin in a cohort of 77 patients submitted to Hematopoietic allogeneic stem cell transplantation (HSCT) in our department. Blood samples were been collected at baseline, day +30, GvHD onset and GvHD resolution.

RESULTS

REG3α levels showed an association only with acute GvHD. Elafin and ST2 levels varied according to both acute and chronic GvHD occurrence. BAFF concentration showed an inverse association with acute GvHD development. Interestingly, baseline BAFF and ST2 levels predicted post-HSCT survival. No associations were found for CXCL9.

CONCLUSIONS

Except for CXCL9, the protein levels seem to change according to GvHD development, independently from organ involvement and grading. Pretransplant ST2 and BAFF appeared to be predictors for survival after HSCT.

The association between acute graft-versus-host disease and antimicrobial peptide expression in the gastrointestinal tract after allogeneic stem cell transplantation

Intestinal microbiota disruption is associated with acute gastrointestinal (GI) Graft-versus-Host Disease (GvHD) and poor outcome after allogeneic stem cell transplantation (ASCT). Here, in a retrospective analysis of 200 patients undergoing ASCT at the Regensburg University Medical Center, we assessed the relative expression of Paneth cell antimicrobial peptides (AMPs), Human Defensins (HD) 5 and 6 and regenerating islet-derived 3α (Reg3α), in 292 human intestinal biopsies as well as Reg3α serum levels in relation to acute GI GvHD. In the absence of GI GvHD, the relative expression of Paneth cell AMPs was significantly higher in the small intestine (duodenum to ileum) than in the stomach and large intestine (cecum to rectum) for Reg3α (p≤0.001), HD5 (p≤0.002) and HD6 (p≤0.02). Acute stage 2-4 GI GvHD was associated with reduced expression of AMPs in the small intestine (p≤0.01) in comparison to stage 0-1 disease, accompanied by a decrease in Paneth cell count in case of severe acute GI GvHD (p<0.001). The opposite held true for the large intestine as we found stage 2-4 GI GvHD correlated with significantly higher expression of HD5, HD6, and Reg3α compared to mild or no acute GI GvHD (p≤0.002). Severe GI GvHD in both the lower and the upper GI tract also correlated with higher serum concentrations of Reg3α (p = 0.002). As indirect markers of intestinal microbiome diversity low levels of urinary 3-indoxyl sulfate levels were associated with severe stages of acute GI GvHD compared to mild stage or no acute GI GvHD (p = 0.05). In conclusion, acute GI GvHD correlates with intestinal expression of HD5, HD6 and Reg3α as well as Reg3α serum levels and is associated with intestinal dysbiosis.

The intestinal barrier function and its involvement in digestive disease

The gastrointestinal mucosal surface is lined with epithelial cells representing an effective barrier made up with intercellular junctions that separate the inner and the outer environments, and block the passage of potentially harmful substances. However, epithelial cells are also responsible for the absorption of nutrients and electrolytes, hence a semipermeable barrier is required that selectively allows a number of substances in while keeping others out. To this end, the intestine developed the "intestinal barrier function", a defensive system involving various elements, both intra- and extracellular, that work in a coordinated way to impede the passage of antigens, toxins, and microbial byproducts, and simultaneously preserves the correct development of the epithelial barrier, the immune system, and the acquisition of tolerance against dietary antigens and the intestinal microbiota. Disturbances in the mechanisms of the barrier function favor the development of exaggerated immune responses; while exact implications remain unknown, changes in intestinal barrier function have been associated with the development of inflammatory conditions in the gastrointestinal tract. This review details de various elements of the intestinal barrier function, and the key molecular and cellular changes described for gastrointestinal diseases associated with dysfunction in this defensive mechanism.

Mucosal Ecological Network of Epithelium and Immune Cells for Gut Homeostasis and Tissue Healing

The intestinal epithelial barrier includes columnar epithelial, Paneth, goblet, enteroendocrine, and tuft cells as well as other cell populations, all of which contribute properties essential for gastrointestinal homeostasis. The intestinal mucosa is covered by mucin, which contains antimicrobial peptides and secretory IgA and prevents luminal bacteria, fungi, and viruses from stimulating intestinal immune responses. Conversely, the transport of luminal microorganisms-mediated by M, dendritic, and goblet cells-into intestinal tissues facilitates the harmonization of active and quiescent mucosal immune responses. The bacterial population within gut-associated lymphoid tissues creates the intratissue cohabitations for harmonized mucosal immunity. Intermolecular and intercellular communication among epithelial, immune, and mesenchymal cells creates an environment conducive for epithelial regeneration and mucosal healing. This review summarizes the so-called intestinal mucosal ecological network-the complex but vital molecular and cellular interactions of epithelial mesenchymal cells, immune cells, and commensal microbiota that achieve intestinal homeostasis, regeneration, and healing.

Research Advance in Intestinal Mucosal Barrier and Pathogenesis of Crohn's Disease

To date, the etiology and pathogenesis of Crohn's disease (CD) have not been fully elucidated. It is widely accepted that genetic, immune, and environment factors are closely related to the development of CD. As an important defensive line for human body against the environment, intestinal mucosa is able to protect the homeostasis of gut bacteria and alleviate the intestinal inflammatory and immune response. It is evident that the dysfunction of intestinal mucosa barriers plays a crucial role in CD initiation and development. Yet researches are insufficient on intestinal mucosal barrier's action in the prevention of CD onset. This article summarizes the research advances about the correlations between the disorders of intestinal mucosal barriers and CD.

Intestinal FoxO signaling is required to survive oral infection in Drosophila

The intestinal immune system is tailored to fight pathogens effectively while tolerating the indigenous microbiota. Impairments of this homeostatic interaction may contribute to the etiology of various diseases including inflammatory bowel diseases. However, the molecular architecture underlying this complex regulatory interaction is not well understood. Here, we show that the fruit fly Drosophila melanogaster has a multilayered intestinal immune system that ensures strictly localized antimicrobial responses. Enterocytes, a major cell population of the intestine, produced antimicrobial peptides (AMPs) in a FoxO- but not NF-κB-dependent manner. Consequently, animals impaired in FoxO-mediated signaling had a significantly lowered resistance to intestinal infections; they were unable to increase the expression of AMP genes and males showed an increased bacterial load in response to an infection. Conventional innate immune signaling converging onto NF-κB activation was operative in only a few regions of the intestine, comprising the proventriculus, copper cells, and intestinal stem cells. Taken together, our results imply that danger-mediated as well as conventional innate immune signaling constitute modules that contribute to the fruit fly's intestinal immune system. We propose that this special architecture ensures localized and efficient antimicrobial responses against invasive pathogens while preserving the microbiota.

Characterization of paneth cells in alpacas (Vicugna pacos, Mammalia, Camelidae)

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We determinated Paneth Cells in fetus, offspring and adults alpacas.

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Studies of Paneth cells were done by cytochemistry, immunohistochemistry and lectinhistochemistry techniques.

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We describe Paneth Cell morphometry in fetal, young and adult alpacas.

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We founded Paneth cells in all the small intestinal sections from mid-gestation.

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PC location was similar to that described in other mammals, however they were more columnar than the conventional pyramidal shape.

Paneth cells are secretory epithelial cells of the innate immune system of the intestine of several mammals, including alpacas. Little is known about the latter; thus, in the present study we described the morphology and histochemical characteristics of Paneth cells in healthy fetuses, and young and adult alpacas. For this purpose, samples of duodenum, jejunum and ileum were taken from 6 fetuses at different days of pregnancy (between days 221–330), 66 offsprings (between 0 and 45-days-old) and 5 adult alpacas (>2-years-old). Samples were fixed in 10% buffered formalin and processed for histological and morphometrical analysis using HE and Masson Trichomićs technique. Immunohistochemistry was used to identify Paneth cells using anti-lysozyme antibody. In addition, the lectinhistochemichal binding-pattern of Paneth celĺs granules was evaluated. Lyzozyme was immunohistochemically detected in the granules of Paneth cells from day 283 of pregnancy in all the small intestinal sections of the studied fetuses. In newborn alpacas Paneth cells were initially found in the duodenum, but the following days (days 18–21 after birth) they were also found in the ileum. Their size gradually increased after birth, but then no significant differences were found. In adult alpacas the number was lower than offsprings. We suggest that Paneth cells early differentiate in the small intestine of alpacas, and the increase in their number during the first two weeks of life strongly support their possible involvement in the intestinal defensive functions against the enteric diseases that occur during the lactancy stage.

Activation of intestinal epithelial Stat3 orchestrates tissue defense during gastrointestinal infection

Gastrointestinal infections with EHEC and EPEC are responsible for outbreaks of diarrheal diseases and represent a global health problem. Innate first-line-defense mechanisms such as production of mucus and antimicrobial peptides by intestinal epithelial cells are of utmost importance for host control of gastrointestinal infections. For the first time, we directly demonstrate a critical role for Stat3 activation in intestinal epithelial cells upon infection of mice with Citrobacter rodentium – a murine pathogen that mimics human infections with attaching and effacing Escherichia coli. C. rodentium induced transcription of IL-6 and IL-22 in gut samples of mice and was associated with activation of the transcription factor Stat3 in intestinal epithelial cells. C. rodentium infection induced expression of several antimicrobial peptides such as RegIIIγ and Pla2g2a in the intestine which was critically dependent on Stat3 activation. Consequently, mice with specific deletion of Stat3 in intestinal epithelial cells showed increased susceptibility to C. rodentium infection as indicated by high bacterial load, severe gut inflammation, pronounced intestinal epithelial cell death and dissemination of bacteria to distant organs. Together, our data implicate an essential role for Stat3 activation in intestinal epithelial cells during C. rodentium infection. Stat3 concerts the host response to bacterial infection by controlling bacterial growth and suppression of apoptosis to maintain intestinal epithelial barrier function.

Down-regulation of human enteric antimicrobial peptides by NOD2 during differentiation of the paneth cell lineage

Ileal Crohn's disease (CD) arising from the alteration of intestinal homeostasis is characterized by two features, namely a decrease in Paneth cell-produced antimicrobial peptides that play a key role in maintaining this balance and an increase in NOD2, an intracellular sensor. Although mutations in NOD2 are highly correlated with the incidence of CD, the physiological role of NOD2 in intestinal immunity remains elusive. Here, we show that NOD2 can down-regulate the expression of human enteric antimicrobial peptides during differentiation of the Paneth cell lineage. This finding, which links the decrease of human enteric antimicrobial peptides to increased NOD2 in ileal CD patients, provides a new view into the pathogenesis of ileal CD.

Cancer stem cells: the promise and the potential

Despite the advancement of treatment modalities, many cancer patients experience tumor recurrence and metastasis at regional or distant sites. Evolving understanding of tumor biology has led to the hypothesis that tumors may possess a stem cell-like subpopulation known as cancer stem cells (CSCs) that may be involved in driving tumor propagation and pathogenesis. Like normal stem cells (NSCs), CSCs can be identified by markers such as CD133, CD44, and ALDH. CSCs have the ability to self-renew and differentiate into different tumor components through stemness pathways, such as Wnt, TGF-β, STAT, and Hippo-YAP/TAZ, among others. In NSCs, stemness pathways are strictly regulated and control many important biologic processes, including embryogenesis and intestinal crypt cellular regulation. In contrast, stemness pathways in CSCs are significantly dysregulated. Combining current drugs with the targeting of these stemness pathways may significantly improve patient prognosis. The aim of this supplement is to update clinicians on the accumulated evidence characterizing the role of CSCs in tumor initiation, heterogeneity, therapy resistance, and recurrence and metastasis, and the potential for effectively treating patients.

Regulation of human enteric α-defensins by NOD2 in the Paneth cell lineage

Human enteric α-defensins (HD5 and HD6), major antimicrobial peptides produced by Paneth cells in the intestine, play important roles in intestinal innate immunity. Since their expression is decreased in Crohn's disease (CD), with decreased expression being more pronounced in the presence of NOD2 mutations, it would be extremely interesting to investigate the mechanism by which NOD2 may regulate expression of human enteric α-defensins. Here we show that although NOD2 by itself can slightly up-regulate expression of enteric α-defensins mainly through activation of the NF-κB pathway, it can strongly down-regulates their expression during differentiation of the Paneth cell lineage mainly by inhibiting activation of the MAPK pathway. Since NOD2 is over-expressed in CD and mutant NOD2 cannot result in NF-κB activity, our finding can provide an explanation of the previous observation showing decreased expression of human enteric α-defensin in CD and even more so in the presence of NOD2 mutations. In addition, this finding provides a new view on the function of NOD2 in regulating intestinal innate immunity.

Prognostic biomarkers for acute graft-versus-host disease risk after cyclophosphamide-fludarabine nonmyeloablative allotransplantation

Five candidate plasma biomarkers (suppression of tumorogenesis 2 [ST2], regenerating islet-derived-3α [REG3α], elafin, tumor necrosis factor receptor 1 [TNFR1], and soluble IL-2 receptor-alpha [sIL2Rα]) were measured at specific time points after cyclophosphamide/fludarabine-based nonmyeloablative allotransplantation (NMAT) in patients who did or did not develop acute graft-versus-host disease (aGVHD). Plasma samples from 34 patients were analyzed at days +7, +14, +21, and +30. At a median follow-up of 358 days, 17 patients had experienced aGVHD with a median time to onset at day +36. Risk of aGVHD was associated with elevated plasma ST2 concentrations at day +7 (c-statistic = .72, P = .03), day +14 (c-statistic = .74, P = .02), and day +21 (c-statistic = .75, P = .02); elevated plasma REG3α concentrations at day +14 (c-statistic = .73, P = .03), day +21 (c-statistic = .76, P = .01), and day +30 (c-statistic = .73, P = .03); and elevated elafin at day +14 (c-statistic = .71, P = .04). Plasma concentrations of TNFR1 and sIL2Rα were not associated with aGVHD risk at any of the time points studied. This study identified ST2, REG3α, and elafin as prognostic biomarkers to evaluate risk of aGVHD after cyclophosphamide/fludarabine-based NMAT. These results need to be confirmed in an independent validation cohort.

ClC-3 chloride channel/antiporter defect contributes to inflammatory bowel disease in humans and mice

BACKGROUND

ClC-3 channel/antiporter plays a critical role in a variety of cellular activities. ClC-3 has been detected in the ileum and colon.

OBJECTIVE

To determine the functions of ClC-3 in the gastrointestinal tract.

DESIGN

After administration of dextran sulfate sodium (DSS) or 2,4,6-trinitrobenzenesulfonic acid (TNBS), intestines from ClC-3-/- and wild-type mice were examined by histological, cellular, molecular and biochemical approaches. ClC-3 expression was determined by western blot and immunostaining.

RESULTS

ClC-3 expression was reduced in intestinal tissues from patients with UC or Crohn's disease and from mice treated with DSS. Genetic deletion of ClC-3 increased the susceptibility of mice to DSS- or TNBS-induced experimental colitis and prevented intestinal recovery. ClC-3 deficiency promoted DSS-induced apoptosis of intestinal epithelial cells through the mitochondria pathway. ClC-3 interacts with voltage-dependent anion channel 1, a key player in regulation of mitochondria cytochrome c release, but DSS treatment decreased this interaction. In addition, lack of ClC-3 reduced the numbers of Paneth cells and impaired the expression of antimicrobial peptides. These alterations led to dysfunction of the epithelial barrier and invasion of commensal bacteria into the mucosa.

CONCLUSIONS

A defect in ClC-3 may contribute to the pathogenesis of IBD by promoting intestinal epithelial cell apoptosis and Paneth cell loss, suggesting that modulation of ClC-3 expression might be a new strategy for the treatment of IBD.

A20 controls intestinal homeostasis through cell-specific activities

The transcription factor NF-κB is indispensable for intestinal immune homeostasis, but contributes to chronic inflammation and inflammatory bowel disease (IBD). A20, an inhibitor of both NF-κB and apoptotic signalling, was identified as a susceptibility gene for multiple inflammatory diseases, including IBD. Despite absence of spontaneous intestinal inflammation in intestinal epithelial cell (IEC) specific A20 knockout mice, we found additional myeloid-specific A20 deletion to synergistically drive intestinal pathology through cell-specific mechanisms. A20 ensures intestinal barrier stability by preventing cytokine-induced IEC apoptosis, while A20 prevents excessive cytokine production in myeloid cells. Combining IEC and myeloid A20 deletion induces ileitis and severe colitis, characterized by IEC apoptosis, Paneth and goblet cell loss, epithelial hyperproliferation and intestinal microbiota dysbiosis. Continuous epithelial cell death and regeneration in an inflammatory environment sensitizes cells for neoplastic transformation and the development of colorectal tumours in aged mice.

Effect of a probiotic mixture on intestinal microflora, morphology, and barrier integrity of broilers subjected to heat stress

The current study investigated the efficacy of a probiotic mixture on ameliorating heat stress-induced impairment of intestinal microflora, morphology, and barrier integrity in broilers. The probiotic mixture contained Bacillus licheniformis, Bacillus subtilis, and Lactobacillus plantarum. Three hundred sixty 21-d-old Ross 308 male broilers were allocated in 4 experimental treatments, each of which was replicated 6 times with 15 broilers per replicate. A 2 × 2 factorial design was used in the study, and the main factors were composed of diet (basal diet or addition of 1.5 g/kg of probiotic mixture) and temperature (thermoneutral zone or heat stress). From d 22 to 42, birds were either raised in a thermoneutral zone (22°C) or subjected to cyclic heat stress by exposing them to 33°C for 10 h (from 0800 to 1800) and 22°C from 1800 to 0800. Compared with birds kept in the thermoneutral zone, birds subjected to heat stress had reduced ADG and ADFI; lower viable counts of Lactobacillus and Bifidobacterium and increased viable counts of coliforms and Clostridium in small intestinal contents; shorter jejunal villus height, deeper crypt depth, and lower ratio of villus height to crypt depth; decreased jejunal transepithelial electrical resistance and a higher level of jejunal paracellular permeability of fluorescein isothiocyanate dextran 4 kDa; and downregulated protein levels of occludin and zonula occludens-1 (P < 0.05). Supplemental probiotics increased (P < 0.05) small intestinal Lactobacillus and Bifidobacterium, jejunal villus height, protein level of occludin, and decreased (P < 0.05) feed to gain ratio and small intestinal coliforms. These results indicate that dietary addition of probiotic mixture was effective in partially ameliorating intestinal barrier function. But no temperature × diet interaction was observed in the present study, revealing that the supplemented probiotics had the same effect at both temperatures.

Intestinal IgA⁺ cell numbers as well as IgA, IgG, and IgM contents correlate with mucosal humoral immunity of broilers during supplementation with high fluorine in the diets

Fluoride (F), a well-recognized harmful substance, is easily absorbed by the intestinal mucosa. The intestinal mucosal immune system is equipped with unique innate and adaptive defense mechanisms that provide a first line of protection against infectious agents. Meanwhile, immunoglobulins are the major secretory products of the adaptive immune system and their levels can be a strong indicator of a disease or condition. In this study, therefore, we investigated the effects of high dietary fluorine on the numbers of immunoglobulin A-positive (IgA(+)) cells in the lamina propria of intestines (duodenum, jejunum and ileum) by immunohistochemistry as well as on the contents of immunoglobulin A (IgA), immunoglobulin G (IgG), and immunoglobulin M (IgM) in the mucosa of intestines (duodenum, jejunum, and ileum) by enzyme-linked immunosorbent assay (ELISA). A total of 280 1-day-old healthy avian broilers were randomly divided into four groups and fed on a corn-soybean basal diet as control diet (fluorine 22.6 mg/kg) or the same basal diet supplemented with 400, 800, and 1,200 mg/kg fluorine (high fluorine groups I, II, and III) in the form of sodium fluoride (NaF) for 42 days. The experimental data showed that the numbers of IgA(+) cells as well as the IgA, IgG, and IgM contents were significantly decreased (P < 0.01 or P < 0.05) in the high fluorine groups II and III when compared with those of the control group. It was concluded that dietary fluorine in the range of 800-1,200 mg/kg significantly reduced the numbers of the IgA(+) cells and the contents of aforementioned immunoglobulins in the intestines (duodenum, jejunum, and ileum) of broilers, which could finally impact the mucosal humoral immune function in the intestines by a way that reduces the lymphocyte population and/or lymphocyte activation.

Apoptosis, necrosis and necroptosis: cell death regulation in the intestinal epithelium

Intestinal epithelial cells (IEC) are organised as a single cell layer which covers the intestine. Their primary task is to absorb nutrients present in the intestinal lumen. However, IEC also play an important role in the immune defence of our body by building a barrier that separates the bowel wall from potentially hazardous bacteria present in the gut lumen. The life cycle of IEC is determined by the time span in which cells migrate from their place of origin at the crypt base to the villus tip, from where they are shed into the lumen. Cell death in the intestinal epithelium has to be tightly regulated and irregularities might cause pathologies. Excessive cell death has been associated with chronic inflammation as seen in patients with Crohn's disease and ulcerative colitis. While until recently apoptosis was discussed as being essential for epithelial turnover and tissue homeostasis in the intestinal epithelium, recent data using gene deficient mice have challenged this concept. Moreover, an apoptosis-independent mode of programmed cell death, termed necroptosis, has been identified and described in the intestinal epithelium. The following article reviews previous studies on cell death regulation in IEC and a potential role of necroptosis for gut homeostasis.

Impact of NOD2 polymorphisms on infectious complications following chemotherapy in patients with acute myeloid leukaemia

We sought to investigate the relationship between polymorphisms of the NOD2 gene and infectious complications following intensive induction chemotherapy in patients with acute myeloid leukaemia (AML). We hypothesised that single nucleotide polymorphisms (SNPs) of the NOD2 gene are associated with a higher rate of infections during the phase of severe neutropenia. In 131 AML patients receiving induction therapy, the presence of the three most frequent polymorphisms of NOD2 (Arg702Trp, Gly908Arg, Leu1007fsinsC) was analysed. SNP analyses by means of genomic PCR incorporating fluorescence-labelled probes with characteristic melting curves were performed using the LightCycler platform. Our data suggest a significantly lower probability of mucositis or enteritis in AML patients lacking any of the three evaluated NOD2 polymorphisms. Furthermore, bloodstream cultures of AML patients carrying either a missense or a frameshift mutation of NOD2 were significantly more frequently tested positive concerning Streptococcus spp. In contrast, the presence of NOD2 polymorphisms had no impact on such important infectious complications as systemic inflammatory response syndrome or sepsis, the rate of central venous catheter infections or the incidence of pneumonia including fungal infections. Our data represent one of the first reports investigating the impact of polymorphisms of the innate immune system on infectious complications in patients with neutropenia following chemotherapy. A correlation between NOD2 polymorphisms and infectious events in AML patients is demonstrated.

Have we made progress in the treatment of GVHD?

One reason for the lack of progress in the treatment of acute graft versus host disease (GVHD) is the lack of reliable biomarkers. GVHD of the gastrointestinal (GI) tract is closely associated with non-relapse mortality (NRM) following hematopoietic cell transplantation (HCT). Using an unbiased, large-scale, quantitative proteomic discovery approach, we identified candidate biomarkers that were increased in plasma from HCT patients with GI GVHD. We then validated the lead candidate, REG3α, by ELISA in samples from more than 1000 HCT patients from three transplant centers. Plasma REG3α concentrations were 3-fold higher in patients at GI GVHD onset than in all other patients. REG3α concentrations correlated most closely with lower GI GVHD at GVHD onset and predicted response to therapy at 4 weeks, 1-year NRM, and 1-year survival (P ≤ 0.001). Multivariate analysis showed that advanced clinical stage, severe histologic damage, and high REG3α concentrations at the diagnosis of GVHD independently predicted 1-year NRM, which progressively increased with higher numbers of onset risk factors present. We conclude that REG3α is a plasma biomarker of GI GVHD that can be combined with clinical stage and histologic grade to improve risk stratification of patients, perhaps providing a platform for advances in the treatment of high-risk GVHD.

Wnt signaling in gut organogenesis

Wnt signaling regulates some aspect of development of nearly all endoderm-derived organs and Wnts mediate both differentiation and proliferation at different steps during visceral organogenesis. Wnt2b induces liver formation in zebrafish 1 and may combine with other inducers, Fibroblast Growth Factors 1 & 4 and Bone Morphogenetic Protein 4, to specify the mammalian liver.2-5 Later in development, Wnts are critical for liver expansion and, finally, for terminal hepatocyte differentiation,6-12 as reviewed elsewhere in this issue (Monga). Likewise, in the pancreas, Wnts drive proliferation of exocrine and endocrine cells13,14 and promote acinar cell differentiation,13,15 as reviewed in the chapter by Murtaugh. Here we examine the intricate involvement of Wnt signaling in growth and differentiation of the digestive tract.

The mucosal response of hamsters exposed to weekly repeated infections with the hookworm Ancylostoma ceylanicum

An experiment was carried out to assess mucosal changes in hamsters exposed to weekly repeated low-intensity infections with the hookworm Ancylostoma ceylanicum. The experiment included control groups of naïve, uninfected hamsters and groups that received a single-pulse primary infection. Changes in the intestinal architecture and in the density of inflammatory cells in the mucosa, including mast cells, goblet cells, Paneth cells and eosinophils were examined in relation to changes in hookworm burdens. As in the single-pulse primary infection, hamsters exposed to repeated infections responded with marked changes in the intestinal architecture and in mucosal populations of inflammatory cells. However, there were distinct differences in the kinetics of the responses to these two types of infection (primary single-pulse and repeated). The reduction in villous height and the increase in crypt depth in animals exposed to repeated infections were both initially slower but eventually equalled and exceeded the responses in hamsters given a chronic primary infection, despite the presence of fewer adult worms in the former. Similarly, changes in the mitotic figures of epithelial cells in the mucosa and the mast cell response were both initially slower and less intense in repeatedly infected hamsters, but eventually exceeded the response to primary infection. Furthermore, the eosinophil response was found to be initially greater in repeated infections and overall more persistent. In contrast, both goblet and Paneth cell responses were less marked in repeatedly infected animals compared to those carrying a primary infection. These results are discussed in the context of host protective resistance to infection with A. ceylanicum.

Gastrointestinal pathology in celiac disease: a case series of 150 consecutive newly diagnosed patients

The main histologic feature of celiac disease is increased intraepithelial lymphocytes (IELs) with or without villous atrophy of the duodenal mucosa. The aim of this study was to document a broad range of additional morphologic changes in intestinal mucosa biopsy specimens from patients with celiac disease. Our cohort comprised 150 patients with positive tissue transglutaminase serologic findings; 7 were at Corazza stage A1, 58 at stage B1, and 85 at stage B2. IEL counts per 100 epithelial cells ranged from 34 to 156 (mean, 88.6); a significant neutrophilic infiltrate was present in 85 cases (56.7%); eosinophil count ranged from 3 to 50 per high-power field (mean, 14.6). Additional findings included morphologic changes in enterocytes in 68.7%, subepithelial collagen thickening in 45.3%, and associated lymphocytic gastritis in 30.4% of patients. We demonstrated that these underrecognized features, which can be misleading, are not uncommon in celiac disease and were positively associated with more advanced stages of the disease (P < .0001).

Regenerating islet-derived 3-alpha is a biomarker of gastrointestinal graft-versus-host disease

There are no plasma biomarkers specific for GVHD of the gastrointestinal (GI) tract, the GVHD target organ most associated with nonrelapse mortality (NRM) following hematopoietic cell transplantation (HCT). Using an unbiased, large-scale, quantitative proteomic discovery approach to identify candidate biomarkers that were increased in plasma from HCT patients with GI GVHD, 74 proteins were increased at least 2-fold; 5 were of GI origin. We validated the lead candidate, REG3α, by ELISA in samples from 1014 HCT patients from 3 transplantation centers. Plasma REG3α concentrations were 3-fold higher in patients at GI GVHD onset than in all other patients and correlated most closely with lower GI GVHD. REG3α concentrations at GVHD onset predicted response to therapy at 4 weeks, 1-year NRM, and 1-year survival (P ≤ .001). In a multivariate analysis, advanced clinical stage, severe histologic damage, and high REG3α concentrations at GVHD diagnosis independently predicted 1-year NRM, which progressively increased with higher numbers of onset risk factors present: 25% for patients with 0 risk factors to 86% with 3 risk factors present (P < .001). REG3α is a plasma biomarker of GI GVHD that can be combined with clinical stage and histologic grade to improve risk stratification of patients.

Caspase-8 regulates TNF-α-induced epithelial necroptosis and terminal ileitis

Dysfunction of the intestinal epithelium is believed to result in excessive translocation of commensal bacteria into the bowel wall that drives chronic mucosal inflammation in Crohn's disease; an incurable inflammatory bowel disease in humans characterized by inflammation of the terminal ileum¹. Beside the physical barrier established by the tight contact of cells, specialized epithelial cells such as Paneth cells and goblet cells provide innate immune defence functions by secreting mucus and antimicrobial peptides which hamper access and survival of bacteria adjacent to the epithelium². Epithelial cell death is a hallmark of intestinal inflammation and has been discussed as a pathogenic mechanism driving Crohn's disease (CD) in humans³. However, the regulation of epithelial cell death and its role in intestinal homeostasis remains poorly understood.

Here we demonstrate a critical role for caspase-8 in regulating necroptosis of intestinal epithelial cells (IEC) and terminal ileitis. Mice with a conditional deletion of caspase-8 in the intestinal epithelium (Casp8^ΔIEC) spontaneously developed inflammatory lesions in the terminal ileum and were highly susceptible to colitis. Casp8^ΔIEC mice lacked Paneth cells and showed reduced numbers of goblet cells suggesting dysregulated anti-microbial immune cell functions of the intestinal epithelium. Casp8^ΔIEC mice showed increased cell death in the Paneth cell area of small intestinal crypts. Epithelial cell death was induced by tumor necrosis factor (TNF) -α, was associated with increased expression of receptor-interacting protein 3 (RIP3) and could be inhibited upon blockade of necroptosis. Finally, we identified high levels of RIP3 in human Paneth cells and increased necroptosis in the terminal ileum of patients with Crohn's disease, suggesting a potential role of necroptosis in the pathogenesis of this disease. Taken together, our data demonstrate a critical function of caspase-8 in regulating intestinal homeostasis and in protecting IEC from TNF-α induced necroptotic cell death.

Inflammatory bowel disease

This review focuses on the prominent etiological and pathogenetic aspects of inflammatory bowel disease (IBD), with particular attention being paid to the mucosal immune response to commensal micro-organisms in health and disease. Pathogenetic implications for target therapy will also be discussed. The clinical presentation, diagnostic aspects, and currently recommended therapeutic options for the two main types of IBD are also taken into consideration, including manifestations of these conditions in the oral cavity.

Salmonella Interaction with and Passage through the Intestinal Mucosa: Through the Lens of the Organism

Salmonella enterica serotypes are invasive enteric pathogens spread through fecal contamination of food and water sources, and represent a constant public health threat around the world. The symptoms associated with salmonellosis and typhoid disease are largely due to the host response to invading Salmonella, and to the mechanisms these bacteria employ to survive in the presence of, and invade through the intestinal mucosal epithelia. Surmounting this barrier is required for survival within the host, as well as for further dissemination throughout the body, and subsequent systemic disease. In this review, we highlight some of the major hurdles Salmonella must overcome upon encountering the intestinal mucosal epithelial barrier, and examine how these bacteria surmount and exploit host defense mechanisms.

Response of crypt paneth cells in the small intestine following total-body gamma-irradiation

Ionizing irradiation causes damage and functional failure of irradiation-sensitive systems and tissues such as small intestine. The molecular mechanisms underlying inflammatory and adaptive responses to acute irradiation damage are poorly understood. Using a mouse model of total-body γ-irradiation, we assessed the irradiation response of crypt host-defense Paneth cells by measuring alpha-defensin 4 (AD4) expression and correlated the gathered data with activation of the caspase-1/IL-1β inflammatory signaling cascade. The irradiation injury was produced in CD2F1 mice exposed to 9.25 Gy γ-radiation. This dose resulted in 85-100 percent mortality at the 15(th) day post-irradiation. Small intestine tissue samples were collected at the 7th day post-irradiation. Assessment of irradiation-associated pro-inflammatory alterations in small intestine tissue and expression of AD4 in Paneth cells was conducted using confocal immunofluorescence imaging, transmission electron microscopy (TEM), light microscopy, and immunoblotting techniques. The small intestine analysis revealed an increase in the precursor form of IL-1β, the activated form of IL-1β, and the activated form of caspase-1 (p10 CASP-1) at the 7(th) day post-irradiation. Immunoprecipitation analysis showed increased interaction between IL-1β and p10 CASP-1 after irradiation. This effect was observed in the irradiated small intestine and CD15-positive Paneth cells using confocal imaging techniques. The pro-inflammatory alterations in Paneth cells were accompanied by increases in AD4 mRNA and its 8 kD peptide product. Paneth cell secretory activity was observed at the sites of bacterial translocation in the crypt lumens. These data suggest that Paneth cells can contribute to small intestine inflammatory remodeling during the post-irradiation period.

Shigella deploy multiple countermeasures against host innate immune responses

Although the intestinal epithelium is equipped with multiple defense systems that sense bacterial components, transmit alarms to the immune system, clear the bacteria, and renew the injured epithelial lining, mucosal bacterial pathogens are capable of efficiently colonizing the intestinal epithelium, because they have evolved systems that modulate the inflammatory and immune responses of the host and exploit the harmful environments as replicative niches. In this review we highlight current topics concerning Shigella's tactics that interfere with the innate immune systems.

KCNN4 gene variant is associated with ileal Crohn's Disease in the Australian and New Zealand population

OBJECTIVES

Crohn's disease (CD; MIM 266600) is one of the most common forms of inflammatory bowel disease (IBD), and represents a significant burden to health care in developed countries. Our aim was to determine whether a gene in the IBD linkage region on chromosome 19q13, with a role in Paneth cell secretion and T-cell activation, conferred genetic susceptibility to the development of CD.

METHODS

In total, 792 CD cases and 1,244 controls of Australian origin (Caucasian) were genotyped for seven single-nucleotide polymorphisms (SNPs) in the gene encoding the intermediate conductance calcium-activated potassium channel protein (KCNN4) at 19q13.2. CD cases were phenotyped using the Montreal classification. The replication set comprised an additional 326 CD cases and 951 population-based Caucasian controls. Analysis of the KCNN4 mRNA transcript was carried out using quantitative reverse transcriptase-PCR.

RESULTS

KCNN4 SNP rs2306801 was associated with CD (primary P=0.0008, odds ratio (OR) (95% confidence interval (CI)): 0.76 (0.65-0.89); replication P=0.01, OR (95% CI): 0.77 (0.61-0.97). Stratification by disease location identified the association between SNP rs2306801 and ileal CD (P=0.01). Non-inflamed ileal mucosa from CD patients carrying any of the common disease-predisposing NOD2 variants (R702W, G908R, 1007fs) had significantly reduced levels of KCNN4 mRNA expression (P=0.001). KCNN4 protein expression was detected in Paneth cells, and in T cells in inflamed lamina propria.

CONCLUSIONS

Our data implicate the role of KCNN4 in ileal CD. The dual roles of KCNN4 in Paneth cell secretion and T-cell activation and also its nature as a potassium channel make it an important and practical therapeutic target.

The role of the gut mucosal immunity in the development of tolerance against allergy to food

PURPOSE OF REVIEW

To provide an overview on the role of gut mucosal immunity in the development of tolerance against allergy to food.

RECENT FINDINGS

The gastrointestinal tract, through innate and specific immunologic factors, acts as a defense against ingested antigens. In addition to the mucous membrane integrity and digestion, numerous specific immunologic cells and mediators orchestrate such defensive mechanisms. In case of food antigens, the outcome is usually in favor of tolerance. Defects in that barrier, however, can lead to the development of aberrant immunologic responses, including hypersensitivity reactions.

SUMMARY

The prevailing evidence is that healthy mucosal immunity plus appropriate feeding regimen during early infancy are in favor of food tolerance. However, in addition to genetic predisposition, development of allergy is facilitated by defects in the gut barrier (immune or nonimmune) and the food allergen load.

Influence of alemtuzumab on the intestinal Paneth cells and microflora in macaques

Alemtuzumab has been recently introduced for induction therapy in organ transplantation. However, the pathogenesis and molecular mechanism of the impact of such induction therapy on bacterial infections remain to be clarified. We found the alterations of Paneth cells including abnormal Paneth cell granules and expression of lysozyme and defensin 5 in response to lymphocyte depletion by alemtuzumab. Lymphocyte depletion resulted in decreased expression of TNF-alpha, IFN-gamma, IL-10 and TGF-beta in the intestine. The diversity of gut bacteria varied significantly between different times of alemtuzumab treatment. Abnormal expression of granule peptides might result in impairment of host gut microflora. The alterations in bacterial microflora had almost reversed 56days after alemtuzumab treatment, which was consistent with our results that Paneth cells were recovered to secrete antimicrobial peptides to govern gut microflora. These findings indicated the associations between changes of Paneth cell function and gut microflora and supported the important role of Paneth cells to barrier impairment with the use of alemtuzumab in organ transplantation.

Stem cells as potential therapeutic targets for inflammatory bowel disease

The incidence and prevalence of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), are rising. According to some estimates >1 million new cases of IBD arise in the United States annually. The conventional therapies available for IBD range from anti-inflammatory drugs to immunosuppressive agents, but these therapies generally fail to achieve satisfactory results due to their side effects. Interest in a new therapeutic option, that is, biological therapy, has gained much momentum recently due to its focus on different stages of the inflammatory process. Stem cell (SC) research has become a new direction for IBD therapy due to our recent understanding of cell populations involved in the pathogenic process. To this end, hematopoietic and mesenchymal stem cells are receiving more attention from IBD investigators. The intestinal environment, with its crypts and niches, supports incoming embryonic and hematopoietic stem cells and allows them to engraft and differentiate. The above findings suggest that, in the future, SC-based therapy will be a promising alternative to conventional therapy for IBD. In this review, we discuss SCs as potential therapeutic targets for future treatment of IBD.

The mucosal response of hamsters to a low-intensity superimposed secondary infection with the hookworm Ancylostoma ceylanicum

An experiment was conducted to assess the mucosal response to low-dose superimposed challenge with Ancylostoma ceylanicum. Hamsters were assigned to five treatment groups (1–5 respectively): naïve controls; primary immunizing infection controls; challenge controls; immunized, anthelmintic–treated, challenged group; immunized, superimposed challenge group. Group 4 hamsters were resistant to challenge, whereas most of the challenge inoculum larvae established in Group 5. Villus height and crypt depth measurements were initially markedly divergent between these two groups but over time post-challenge (pc) values for both parameters drew nearer and by day 31 pc they were indistinguishable. The greatest change was experienced by Group 4 which showed increasing inflammation and gut pathology during the challenge infection. Mitotic activity in crypts and mast cell counts in the mucosa were highest in Group 5 on day 10 pc, but there was little to distinguish between Groups 4 and 5 by day 31 pc. Goblet cell, eosinophil and Paneth cell counts were very similar throughout in both groups but, in the case of Paneth cells, they were consistent with a possible role in protective immunity to challenge. Some adult worms survived throughout the period of intense inflammation, emphasizing their tremendous resilience and resistance to mucosal host protective responses.