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Paneth cells (PCs), a specialized secretory cell type in the small intestine, are increasingly recognized as having an essential role in host responses to microbiome and environmental stresses. Whether and how commensal and pathogenic microbes modify PC composition to modulate inflammation remain unclear. Using newly developed PC‐reporter mice under conventional and gnotobiotic conditions, we determined PC transcriptomic heterogeneity in response to commensal and invasive microbes at single cell level. Infection expands the pool of CD74+ PCs, whose number correlates with auto or allogeneic inflammatory disease progressions in mice. Similar correlation was found in human inflammatory disease tissues. Infection‐stimulated cytokines increase production of reactive oxygen species (ROS) and expression of a PC‐specific mucosal pentraxin (Mptx2) in activated PCs. A PC‐specific ablation of MyD88 reduced CD74+ PC population, thus ameliorating pathogen‐induced systemic disease. A similar phenotype was also observed in mice lacking Mptx2. Thus, infection stimulates expansion of a PC subset that influences disease progression. Synopsis: Changes in Paneth cell (PC) gene expression and function have been linked to various inflammatory intestinal diseases, such as Crohn's disease. Here, a single‐cell transcriptomic analysis of PC heterogeneity in mice identifies a CD74+ PC subset that is expanded upon inflammation or infection to secrete innate immune response molecules. Single‐cell transcriptome analysis reveals that PC heterogeneity can be modified by microbiota colonization in germ‐free mice.A CD74+ PC subset is expanded upon mouse infection with invasive pathogens, in mouse models of ileitis, and in inflammatory bowel disease–patient biopsies.Paneth cell‐specific ablation of MyD88 pathway dampens the expansion and secretory function of CD74+ PCs upon infection.Deletion of Mptx2, a mucosal pentraxin that is enriched in CD74+ PCs, reduces complement activation and inflammation upon infection. [ABSTRACT FROM AUTHOR]

Cross talk between immune cells and the intestinal crypt is critical in maintaining intestinal homeostasis. Recent studies highlight the direct impact of vitamin D receptor (VDR) signaling on intestinal and microbial homeostasis. However, the tissue‐specific role of immune VDR signaling is not fully understood. Here, we generated a myeloid‐specific VDR knockout (VDRΔLyz) mouse model and used a macrophage/enteroids coculture system to examine tissue‐specific VDR signaling in intestinal homeostasis. VDRΔLyz mice exhibited small intestine elongation and impaired Paneth cell in maturation and localization. Coculture of enteroids with VDR−/− macrophages increased the delocalization of Paneth cells. VDRΔLyz mice exhibited significant changes in the microbiota taxonomic and functional files, and susceptibility to Salmonella infection. Interestingly, loss of myeloid VDR impaired Wnt secretion in macrophages, thus inhibiting crypt β‐catenin signaling and disrupting Paneth cell differentiation in the epithelium. Taken together, our data have demonstrated that myeloid cells regulate crypt differentiation and the microbiota in a VDR‐dependent mechanism. Dysregulation of myeloid VDR led to high risks of colitis‐associated diseases. Our study provided insight into the mechanism of immune/Paneth cell cross talk in regulating intestinal homeostasis. [ABSTRACT FROM AUTHOR]

The small intestine mucosa is lined by specialized cells that form the crypt‐villus axis, which expands its surface. Among the six intestinal epithelial cell types, the Paneth cell is located at the base of the crypt, and it contains numerous granules in its cytoplasm, composed of antimicrobial peptides, such as defensins and lysozyme, and growth factors, such as epidermal growth factor, transforming growth factor‐α, and Wnt ligands. Together, these elements act in the defense against microorganisms, regulation of intestinal microbiota, maintenance, and regulation of stem cell identity. Pathologies that target Paneth cells can disturb such defense activity, but they also affect the maintenance of the stem cell niche. In that way, Crohn's disease, necrotizing enterocolitis, and graft‐versus‐host disease promote a reduction of Paneth cell population, and, consequently, secretion of their products into the lumen of the crypts, making the affected organism predisposed to infections and dysbiosis. Additionally, the emergence of new intestinal cells is also decreased. This review aims to address the main characteristics of Paneth cells, highlighting their multiple functions and the importance of their preservation to ensure bowel homeostasis. [ABSTRACT FROM AUTHOR]

Immune mediators affect multiple biological functions of intestinal epithelial cells (IECs) and, like Paneth and Paneth‐like cells, play an important role in intestinal epithelial homeostasis. IFN‐γ a prototypical proinflammatory cytokine disrupts intestinal epithelial homeostasis. However, the mechanism underlying the process remains unknown. In this study, using in vivo and in vitro models we demonstrate that IFN‐γ is spontaneously secreted in the small intestine. Furthermore, we observed that this cytokine stimulates mitochondrial activity, ROS production, and Paneth and Paneth‐like cell secretion. Paneth and Paneth‐like secretion downstream of IFN‐γ, as identified here, is mTORC1 and necroptosis‐dependent. Thus, our findings revealed that the pleiotropic function of IFN‐γ also includes the regulation of Paneth cell function in the homeostatic gut. [ABSTRACT FROM AUTHOR]

Paneth cells are versatile secretory cells located in the crypts of Lieberkühn of the small intestine. In normal conditions, they function as the cornerstones of intestinal health by preserving homeostasis. They perform this function by providing niche factors to the intestinal stem cell compartment, regulating the composition of the microbiome through the production and secretion of antimicrobial peptides, performing phagocytosis and efferocytosis, taking up heavy metals, and preserving barrier integrity. Disturbances in one or more of these functions can lead to intestinal as well as systemic inflammatory and infectious diseases. This review discusses the multiple functions of Paneth cells, and the mechanisms and consequences of Paneth cell dysfunction. It also provides an overview of the tools available for studying Paneth cells. [ABSTRACT FROM AUTHOR]

Intelectins (intestinal lectins) are highly conserved across chordate evolution and have been implicated in various human diseases, including Crohn's disease (CD). The human genome encodes two intelectin genes, intelectin‐1 (ITLN1) and intelectin‐2 (ITLN2). Other than its high sequence similarity with ITLN1, little is known about ITLN2. To address this void in knowledge, we report that ITLN2 exhibits discrete, yet notable differences from ITLN1 in primary structure, including a unique amino terminus, as well as changes in amino acid residues associated with the glycan‐binding activity of ITLN1. We identified that ITLN2 is a highly abundant Paneth cell‐specific product, which localizes to secretory granules, and is expressed as a multimeric protein in the small intestine. In surgical specimens of ileal CD, ITLN2 mRNA levels were reduced approximately five‐fold compared to control specimens. The ileal expression of ITLN2 was unaffected by previously reported disease‐associated variants in ITLN2 and CD‐associated variants in neighboring ITLN1 as well as NOD2 and ATG16L1. ITLN2 mRNA expression was undetectable in control colon tissue; however, in both ulcerative colitis (UC) and colonic CD, metaplastic Paneth cells were found to express ITLN2. Together, the data reported establish the groundwork for understanding ITLN2 function(s) in the intestine, including its possible role in CD. [ABSTRACT FROM AUTHOR]

The human intestines are constantly under the influence of numerous pathological factors: enteropathogenic microorganisms, food antigens, physico‐chemical stress associated with digestion and bacterial metabolism, therefore it must be provided with a system of protection against adverse impact. Recent studies have shown that Paneth cells play a crucial role in maintaining homeostasis of the small intestines. Paneth cells perform many vital functions aimed at maintaining a homeostatic balance between normal microbiota, infectious pathogens and the human body, regulate the qualitative composition and number of intestinal microorganisms, prevent the introduction of potentially pathogenic species, and protect stem cells from damage. Paneth cells take part in adaptive and protective‐inflammatory reactions. Paneth cells maintain dynamic balance between microbial populations, and the macroorganism, preventing the development of intestinal infections and cancer. They play a crucial role in gastrointestinal homeostasis and may be key factors in the etiopathological progression of intestinal diseases. [ABSTRACT FROM AUTHOR]

Although previous studies show that exogenous nutrients regulate the stem cell function, little is known about the effects of L‐arginine on intestinal stem cells (ISCs). In this study, we utilize mice, small intestinal (SI) organoids, and ISC‐Paneth cell co‐cultured models to clarify the role of L‐arginine in ISC function. We find that exogenous L‐arginine is essential for ISCs proliferation and intestinal epithelial renewal. Our data show that Paneth cells, a critical component of the ISCs niche, augment the ISCs function in response to L‐arginine. Moreover, enhanced the expression of Wnt3a in Paneth cells, which is a ligand of the Wnt/β‐catenin signaling pathway, mediates the effects of L‐arginine on ISCs function. Pre‐treatment with L‐arginine enhances the ISCs pool and protects the gut in response to injury provoked by murine tumor necrosis factor α (TNF‐α) and 5‐Fluorouracil (5‐FU). Our findings establish that the regulation of Wnt3a in the Paneth cell niche by exogenous L‐arginine couples ISCs function and favours a model in which the ISCs niche couples the nutrient levels to ISCs function. [ABSTRACT FROM AUTHOR]

Paneth cells (PCs) are located at the base of small intestinal crypts and secrete the α‐defensins, human α‐defensin 5 (HD‐5) and human α‐defensin 6 (HD‐6) in response to bacterial, cholinergic and other stimuli. The α‐defensins are broad‐spectrum microbicides that play critical roles in controlling gut microbiota and maintaining intestinal homeostasis. Inflammatory bowel disease, including ulcerative colitis and Crohn's disease (CD), is a complicated autoimmune disorder. The pathogenesis of CD involves genetic factors, environmental factors and microflora. Surprisingly, with regard to genetic factors, many susceptible genes and pathogenic pathways of CD, including nucleotide‐binding oligomerization domain 2 (NOD2), autophagy‐related 16‐like 1 (ATG16L1), immunity‐related guanosine triphosphatase family M (IRGM), wingless‐related integration site (Wnt), leucine‐rich repeat kinase 2 (LRRK2), histone deacetylases (HDACs), caspase‐8 (Casp8) and X‐box‐binding protein‐1 (XBP1), are relevant to PCs. As the underlying mechanisms are being unravelled, PCs are identified as the central element of CD pathogenesis, integrating factors among microbiota, intestinal epithelial barrier dysfunction and the immune system. In the present review, we demonstrate how these genes and pathways regulate CD pathogenesis via their action on PCs and what treatment modalities can be applied to deal with these PC‐mediated pathogenic processes. [ABSTRACT FROM AUTHOR]

Xian‐Yang Zhong, Tao Yu, Wa Zhong, Jie‐Yao Li, Zhong‐Sheng Xia, Yu‐Hong Yuan, Zhong Yu, Qi‐Kui Chen. Lgr5 positive stem cells sorted from small intestines of diabetic mice differentiate into higher proportion of absorptive cells and Paneth cells in vitro. Development, Growth & Differentiation 2015, 57 (6), pp. 453–465 (https://onlinelibrary.wiley.com/doi/10.1111/dgd.12226). The above article, published online on 30 June 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal's Editor in Chief Naoto Ueno and John Wiley and Sons Australia, Ltd. following concerns raised by a third party about figures within the article. During the journal's investigation into the concerns raised, the authors were not able to gather comprehensive original data for the relevant figures several years after publication. Accordingly, the editors consider that the results in the published article are unreliable and do not sufficiently support the conclusions. The co‐authors were not available to confirm the retraction. [ABSTRACT FROM AUTHOR]

Summary: Host genetics shape the gut microbiota, and gut dysbiosis increases the risk of acute graft‐versus‐host disease (aGVHD). Paneth cells and microbiota have interactions that contribute to immune regulation. α‐defensin‐5 (HD5) and regenerating islet‐derived protein 3 alpha (Reg3A) are the most abundant Paneth cell antimicrobial peptides (AMPs). We hypothesized that single nucleotide polymorphisms (SNPs) in the genes for HD5 (DEFA5) and Reg3A (REG3A) predict aGVHD risk. We analysed pre‐transplant recipient peripheral blood mononuclear cell samples from randomized Blood and Marrow Transplant Clinical Trials Network (BMT CTN) studies 0201 (94 patients with bone marrow and 93 with peripheral blood grafts) and 0901 (86 patients with myeloablative and 77 with reduced‐intensity conditioning; all using peripheral blood grafts). In multivariable analysis (with a SNP × graft source interaction term in CTN‐0201 and a SNP × conditioning intensity term in CTN‐0901), DEFA5 rs4415345 and rs4610776 were associated with altered incidence of aGVHD grade II–IV [rs4415345 G vs. C: hazard ratio (HR) 0·58, 95% confidence interval (95% CI) 0·37–0·92, P = 0·02; rs4610776 T vs. A: HR 1·53, 95% CI 1·01–2·32, P = 0·05] in CTN‐0201, but not CTN‐0901, suggesting a stronger effect in bone marrow allografts. REG3A SNP was not associated with aGVHD. Host genetics may influence aGVHD risk by modulating Paneth cell function. [ABSTRACT FROM AUTHOR]

Background: Parenteral nutrition (PN) leads to decreased production of Paneth cell-derived antimicrobial peptides and is accompanied by dysbiosis of the gut. The role of gut microbiota in regulating Paneth cell function during PN is unknown.Methods: Male C57BL/6 mice received either an antibiotic cocktail (Abx) or nothing (Normal) in their drinking water for 2 weeks before being fed either standard laboratory chow (Abx-Chow and Normal-Chow) or a continuous infusion of PN solution (Abx-PN and Normal-PN) for 7 days. In a separate experiment, the intestinal contents of mice having received 7 days of Chow or PN were transferred by gavage to germ-free (GF) mice.Results: Antibiotic treatment decreased the protein levels of lysozyme and RegIIIγ and the mRNA level of α-defensin 5, with no further effect by PN compared with chow. However, these measurements were higher in Abx-PN mice than in Normal-PN mice. When compared with Chow→GF, PN→GF mice demonstrated lower body weight, shorter intestinal length, severe atrophy of the ileum villus, and lower levels of lysozyme and RegIIIγ protein and α-defensin 5 mRNA. Interleukin (IL)-22 and IL-17 mRNA levels declined in the ileum. Principal component analysis revealed major differences between the metabolite compositions of the Chow and PN, as well as the Chow→GF and PN→GF groups that appears to indicate aberrant tryptophan metabolism.Conclusions: Gut microbiota plays a vital role in PN-related Paneth cell dysfunction. Dysbiosis during PN might alter the production of microbial metabolites, thereby influencing the production of Paneth cell-derived antimicrobial peptides. [ABSTRACT FROM AUTHOR]

The secretory activity of Paneth cells is related to the bacterial milieu in the small intestine; however, the molecules involved in inducing Paneth cell secretion of enzymes and antimicrobial peptides are not well-defined. Mice treated orally with CpG-oligodeoxynucleotide (ODN), an agonist of Toll-like receptor (TLR) 9, showed rapid and massive Paneth cell degranulation. CpG-ODN-induced degranulation was not observed in TLR9−/− mice or in chimeric TLR9−/− mice reconstituted with wild-type (WT) bone marrow, but was observed in WT mice reconstituted with TLR9−/− bone marrow, indicating a role for TLR9-expressing gastrointestinal cells in CpG recognition. The TLR3 agonist polyinosinic-polycytidylic acid also induced rapid degranulation, whereas the TLR4 and TLR5 agonists LPS and flagellin, respectively, induced late degranulation mediated by TNF-α. Our evidence that TLR9 and TLR3 agonists induce Paneth cell degranulation points to the need for further studies of the mechanisms underlying Paneth cell function as an avenue toward preventing infection and treating inflammatory bowel diseases. J. Cell. Physiol. 227: 1107-1113, 2012. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract Background and Aim: Colorectal Paneth cell metaplasia (PCM) is known to be a sign of idiopathic inflammatory bowel disease (IBD), although its distribution and histogenesis are not fully understood. Objectives of this research were to investigate the spatial distribution of PCM in IBD and other forms of colitis (non-IBD), and to find stimuli causing PCM. Methods: We studied multiple biopsy specimens from 181 patients with ulcerative colitis (UC), 159 with Crohn's disease (CD), 448 with non-IBD, and 78 normal controls. Paneth cell metaplasia frequency, at each colorectal site, was evaluated to find possible differences among diseases, phases of activity, and extents of disease. Results: In non-IBD and controls, PCM was rarely (0–1.9%) seen at distal sites, but frequently (up to 48.7%) found at the ascending colon and cecum (P < 0.001). Paneth cell metaplasia frequency was significantly higher in IBD than in non-IBD patients and controls at distal sites (P < 0.001), but did not differ significantly between UC and CD, or among active, resolving, and quiescent phases. In UC, proctitis and left-sided colitis rarely displayed PCM at unaffected sites. Multiple logistic regression analysis revealed that PCM was positively associated with crypt distortion and mononuclear cell infiltration (P < 0.005), but negatively or not significantly associated with crypt atrophy, mucin depletion, acute inflammation, or phase of activity. Conclusions: Paneth cell metaplasia is a non-specific phenomenon in the proximal colon, but distal PCM, which occurs exclusively in affected mucosa, is a useful marker indicating IBD, even in the inactive phase. Regression analysis suggests that repair and regeneration may be the most potent stimuli causing PCM. [ABSTRACT FROM AUTHOR]

Background. Necrotizing enterocolitis (NEC) is the most common gastrointestinal disorder in premature infants with a high morbidity and mortality. Paneth cell dysfunction has been suggested to be involved in the pathogenesis of NEC. Defensin alpha-6 (DEFA6) is a specific marker for Paneth cells acting as part of the innate immunity in the human intestines. The aim of this study was to investigate the expression of DEFA6 in infants with NEC. Materials and Methods. Infants who underwent bowel resection for NEC at level III NICU in Sweden between August 2004 and September 2013 were eligible for the study. Macroscopically vital tissues were selected for histopathological evaluation. All infants in the control group underwent laparotomy and had ileostomy due to dysmotility, and samples were taken from the site of the stoma. DEFA6 expression was studied by immunohistochemistry. Digital image analysis was used for an objective and precise description of the samples. Results. A total of 12 infants were included in the study, eight with NEC and four controls. The tissue samples were taken from the colon (n=1), jejunum (n=1), and ileum (n=10). Both the NEC and control groups consisted of extremely premature and term infants (control group: 25–40 gestational weeks, NEC group: 23–39 gestational weeks). The postnatal age at the time of surgery varied in both groups (control group: 4–47 days, NEC group: 4–50 days). DEFA6 expression in the NEC group was significantly lower than that in the control group and did not correlate with gestational age. Conclusion. The diminished DEFA6 expression in Paneth cells associated with NEC in this study supports the hypothesis that alpha-defensins are involved in the pathophysiology of NEC. Future studies are needed to elucidate the role of alpha-defensins in NEC aiming at finding preventive and therapeutic strategies against NEC. [ABSTRACT FROM AUTHOR]

We previously reported that acute necrotizing pancreatitis (ANP) after normal or high-fat diet is associated with a decreased number of Paneth cells in ileal crypts. Here, we ablated Paneth cells in a rat model of ANP after normal and high-fat diet to investigate the effects on disease symptoms. Adult male Sprague-Dawley rats received standard rat chow or a high-fat diet for 2 weeks, after which they were treated with dithizone to deplete Paneth cells. Six hours later, ANP was established by retrograde injection of sodium taurocholate into the biliopancreatic duct. Rats were sacrificed at 6, 12, and 24 h for assessment. We found dithizone aggravated ANP-associated pathological injuries to the pancreas and ileum in rats on high-fat or standard diets. Lysozyme expression in ileal crypts was decreased, while serum inflammatory cytokines (TNFα, IL-1β, and IL-17A) and intestinal permeability (serum DAO activity and D-lactate) were increased. Expression of tight junction proteins (claudin-1, zo-1, and occludin) was decreased. Using high-throughput 16S rRNA sequencing, we found dithizone reduced microbiota diversity and altered microbiota composition in rats on high-fat or standard diets. Dithizone decreased fecal short-chain fatty acids (SCFAs) in rats on high-fat or standard diets. Changes in intestinal microbiota correlated significantly with SCFAs, lysozyme, DAO activity, D-lactate, inflammatory cytokines, and pathological injury to the pancreas and ileum in rats on high-fat or standard diets. In conclusion, ablation of Paneth cells exacerbates pancreatic and intestinal injuries in ANP after normal and high-fat diet. These symptoms may be related to changes in the intestinal microbiota. [ABSTRACT FROM AUTHOR]

Background Intestinal microbial ecology is actively regulated by Paneth cell-derived antimicrobial peptides, α-defensins. Graft-versus-host disease ( GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation ( SCT). We previously demonstrated that Paneth cells are targeted by GVHD, and their expression of antimicrobial peptide α-defensins is impaired, leading to a loss of physiological diversity among the microflora and development of bloodstream infection. Herein, we evaluated whether fecal levels of α-defensins could be surrogate marker of intestinal dysbiosis. Methods We directly measured α-defensin cryptdin-1 (Crp1) in fecal pellets of mice with GVHD by using a novel enzyme-linked immunosorbent assay. Results Fecal levels of Crp1 were significantly decreased in mice with GVHD but unchanged in mice without GVHD after SCT. These were correlated with intestinal flora diversity. Conclusion We demonstrate a link between reduced secretion of Paneth cell α-defensins and dysbiosis of intestinal flora in GVHD. Fecal levels of α-defensins could be surrogate markers for intestinal microbial homeostasis. [ABSTRACT FROM AUTHOR]

Intestinal epithelial stem cells ( IESCs) can differentiate into all types of intestinal epithelial cells ( IECs) and Leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) is a marker for IESC. Previous studies reported enhanced proliferation of IECs in diabetic mice. In this study, the in vitro differentiation of Lgr5 positive IESCs sorted from diabetic mice was further investigated. The diabetic mouse model was induced by streptozotocin ( STZ), and crypt IECs were isolated from small intestines. Subsequently, Lgr5 positive IESCs were detected by flow cytometry ( FCM) and sorted by magnetic activated cell sorting ( MACS). Differentiation of the sorted IESCs was investigated by detecting the IEC markers in the diabetic mice using immunostaining, quantitative real-time reverse-transcription polymerase chain reaction ( qRT- PCR), and Western blot analysis, which was compared with normal mice. We found that the proportion of Lgr5 positive cells in the crypt IECs of diabetic mice was higher than that of control mice ( P < 0.05). Lgr5 positive IESCs could be significantly enriched in Lgr5 positive cell fraction sorted by MACS. Furthermore, the absorptive cell marker sucrase-isomaltase ( SI) and the Paneth cell marker lysozyme 1 (Lyz1) were more highly expressed in the differentiated cells derived from Lgr5 positive IESCs of diabetic mice in vitro ( P < 0.05). We demonstrate that the number of Lgr5 positive IESCs is significantly increased in the small intestines of STZ-induced diabetic mice. Lgr5 positive IESCs sorted from the diabetic mice can differentiate into a higher proportion of absorptive cells and Paneth cells in vitro. We characterized the expression of Lgr5 in the small intestine of diabetic mice, and sorted Lgr5 positive intestinal epithelial stem cells ( IESCs) for investigating their differentiation in vitro. We proved that the quantity of Lgr5 positive IESCs was significantly increased in the small intestines of diabetic mice. IESCs sorted from the diabetic mice can differentiate into a higher proportion of absorptive cells and Paneth cells in vitro. [ABSTRACT FROM AUTHOR]

The intestinal microbiota is increasingly acknowledged to play a crucial role in the development of obesity. A shift in intestinal microbiota composition favouring the presence of Firmicutes over Bacteroidetes has been observed in obese subjects. A similar shift has been reported in mice with deficiency of active Paneth cell α-defensins. We aimed at investigating changes in Paneth cell antimicrobial levels in the gut of obese subjects. Next, we studied activation of the unfolded protein response (UPR) as a possible mechanism involved in altered Paneth cell function. Paneth cell numbers were counted in jejunal sections of 15 severely obese (BMI > 35) and 15 normal weight subjects. Expression of Paneth cell antimicrobials human α-defensin 5 (HD5) and lysozyme were investigated using immunohistochemistry, qPCR, and western blot. Activation of the UPR was assessed with western blot. Severely obese subjects showed decreased protein levels of both HD5 and lysozyme, while Paneth cell numbers were unchanged. Lysozyme protein levels correlated inversely with BMI. Increased expression of HD5 ( DEFA5) and lysozyme ( LYZ) transcripts in the intestine of obese subjects prompted us to investigate a possible translational block caused by UPR activation. Binding protein (BiP) and activating transcription factor 4 (ATF4) levels were increased, confirming activation of the UPR in the gut of obese subjects. Furthermore, levels of both proteins correlated with BMI. Involvement of the UPR in the lowered antimicrobial protein levels in obese subjects was strongly suggested by a negative correlation between BiP levels and lysozyme levels. Additionally, indications of ER stress were apparent in Paneth cells of obese subjects. Our findings provide the first evidence for altered Paneth cell function in obesity, which may have important implications for the obesity-associated shift in microbiota composition. In addition, we show activation of the UPR in the intestine of obese subjects, which may underlie the observed Paneth cell compromise. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background and Aims: Chronic gastritis is caused by Helicobacter pylori infection, and gastritis is classified as inflammation, atrophy, and intestinal metaplasia. Detailed pathologic studies have shown that H. pylori settles on the surface of gastric mucosa, and that it is eliminated from metaplastic mucosa. However, its mechanism of natural protection is not well known. Methods: Antimicrobial human enteric defensin expression was determined in the RNA and protein levels. Recombinant enteric defensins were produced with a bacterial expression system and their anti- H. pylori activities were assessed by bactericidal assay. Results: Human enteric defensin (HD)-5 and HD-6 were detected in Paneth cells, which are observed in the gastric metaplastic mucosa as well as small intestinal epithelia. HD-5 protein was coexpressed with trypsin, which is considered to be an activating enzyme of HD-5. Less H. pylori was observed in the intestinal metaplasia with HD-5 expressing Paneth cells. The recombinant defensins showed killing activity against H. pylori at a low concentration in vitro. Conclusions: The human defensins that are expressed in the metaplastic Paneth cells eliminate H. pylori. Metaplastic change may be a purposive development of the human stomach. [ABSTRACT FROM AUTHOR]

R4075 --> 743.15 --> ErbB3 is a RTK family member known to regulate proliferation and growth in the intestinal epithelium. Previous work by our lab determined that targeted Erbb3 deletion from the intestinal epithelium resulted in precocious Paneth cell development and an expanded population in mice. This was associated with increased expression of intestinal stem cell (ISC) markers. Conversely, ileal enteroids treated with the ErbB3 ligand neuregulin (NRG)‐1β had significantly reduced expression of ISC markers, including Lgr5 and Bmi1. These data suggest that ErbB3 restricts secretory cell differentiation and stemness in the intestinal crypt. However, the underlying mechanisms are largely unknown. BMI1 is a proto‐oncogene and member of the PRC complex. Bmi1+ intestinal epithelial cells represent a slow‐cycling ISC population that can regenerate the epithelium following injury and loss of Lgr5+ ISCs. Recent evidence determined that Bmi1+ ISCs are enriched in enteroendocrine markers and can give rise to goblet cells, suggesting BMI1 may be critical for differentiation of secretory lineages. We hypothesized that ErbB3 restricts secretory cell differentiation through regulation of BMI1. Aims: To define ErbB3‐dependent regulation of Bmi1 and determine if ErbB3 restriction of Paneth cell development and differentiation is through suppression of Bmi1. Methods: Mucosal scrapings were collected from Vil‐Cre;Erbb3flox/flox mice and Erbb3flox/flox littermate controls for protein and gene expression analysis. Ileal enteroids and HT‐29 colorectal adenocarcinoma cells were treated with vehicle DMSO, the PI3K inhibitor LY294002 (10 μM), the MEK inhibitor U0126 (5 μM), the BMI1 inhibitor PTC‐209 (1 μM), and/or recombinant NRG‐1β (10 ng/mL). Enteroids and cell monolayers were harvested and prepared for gene expression analysis. RT‐qPCR for Bmi1 and Lyz1 was performed relative to Hprt as a loading control. Statistical analysis by one‐way ANOVA was conducted using Prism 9. Results: Consistent with previous data, BMI1 protein and gene expression were significantly increased in small and large intestinal mucosal scrapings from Vil‐Cre;Erbb3flox/flox mice versus littermate controls. To determine if Bmi1 expression is sensitive to PI3K/Akt or MAPK signaling downstream of ErbB3, HT‐29 cells were treated with inhibitors followed by NRG‐1β after 1 hour, then harvested 24 hours later. PI3K and MAPK inhibition significantly increased Bmi1 expression. NRG‐1β treatment was able to overcome MAPK inhibition to reduce BMI1 expression. Similarly, in ileal enteroids, PI3K and MAPK blockade increased Bmi1 expression and NRG‐1β treatment reversed this effect. To determine whether BMI1 regulates expression of the Paneth cell marker LYZ1, HT‐29 cells were treated with the BMI1 inhibitor PTC‐209. BMI1 inhibition decreased LYZ1 expression. Conclusions: Our data demonstrate that ErbB3 regulates Bmi1 expression through PI3K/Akt and MAPK signaling in both human and mouse intestinal cells. Furthermore, BMI1 activity promotes LYZ1 expression. Together, these results support our hypothesis that ErbB3 regulates secretory cell differentiation through BMI1 in the intestinal epithelium. [ABSTRACT FROM AUTHOR]

Dikov D, Vassilev I, Dimitrakov J. Nonspecific granulomatous prostatitis with calculous ductal ectasia and extensive Paneth cell-like epithelial metaplasia: a case report. APMIS 2005;113:564–7. We present a case of nonspecific granulomatous prostatitis in combination with calculous ductal ectasia and extensive epithelial Paneth cell-like metaplasia in a TURP-specimen. Our report highlights the importance of calculous ductal obstruction and stasis of secretions in the etiopathogenesis of this type of prostatitis. The observed extensive Paneth cell-like metaplastic change in adjacent epithelial cells most likely represents a phenotypic adaptive mechanism directed against foreign antigens and nondegradable lipids in the stagnant intraluminal debris. [ABSTRACT FROM AUTHOR]

Investigates the fine structural and histochemical study of paneth cells in horses. Preparations made for the light microscopic analysis of duodenum; Reactivity of paneth cells to lysosome; Reaction of secretory granules in the peripheral halo layer.

Abstract: Antimicrobial peptides and proteins are key effectors of innate immunity, expressed both by circulating phagocytic cells and by epithelial cells of mucosal tissues. In the human small intestine, Paneth cells are secretory epithelial cells that express the antimicrobials human α-defensin-5 (HD5), HD6, lysozyme and secretory phospholipase A2 (sPLA2), and recent studies have implicated reduced HD5 and HD6 expression levels in the pathogenesis of ileal Crohn’s disease. However, expression levels of these molecules have not been determined routinely by techniques that readily permit quantitative comparisons of their distribution between tissues and samples. Using quantitative real-time PCR with external standards and Northern blot analysis, we compared expression levels of mRNA encoding these four Paneth cell antimicrobial peptides, as well as circulating human neutrophil defensins in several different gastrointestinal tissues and the bone marrow. HD5 and HD6 were the most abundant antimicrobials expressed in the small intestine. The concentration of HD5 mRNA is approximately 5×105 copies per 10ng RNA in the jejunum and ileum; HD6 mRNA levels were about six times lower than those of HD5. With the exception of low levels in the pancreas (103 copies/10ng RNA), the expression of HD5 and HD6 in tissues other than small intestine was at or below detectable limits. The expression of sPLA2 and lysozyme mRNA was observed in the small intestine (approximately, 3×103 and 9×103 copies/10ng RNA, respectively), but also in several other tissues. Lysozyme expression was high in the duodenum (105 copies/10ng RNA), and the protein localized to both Brunner’s glands in the lamina propria and Paneth cells. By comparison, the hematopoietic α-defensins HNP1-3 mRNA were detected at 6×105 copies per 10ng RNA in the bone marrow. These quantitative RT-PCR data from healthy tissues represents the first quantitative topographical assessment of antimicrobial expression in the gastrointestinal tract and provides a means to directly compare expression levels between healthy tissues and disease specimens for multiple antimicrobial peptides. [Copyright &y& Elsevier]

Genetic polymorphisms of autophagy-related genes have been associated with an increased risk to develop inflammatory bowel disease (IBD). Autophagy is an elementary process participating in several cellular events such as cellular clearance and nonapoptotic programmed cell death. Furthermore, autophagy may be involved in intestinal immune homeostasis due to its participation in the digestion of intracellular pathogens and in antigen presentation. In the present study, the role of autophagy in the intestinal epithelial layer was investigated. The intestinal epithelium is essential to maintain gut homeostasis, and defects within this barrier have been associated with the pathogenesis of IBD. Therefore, mice with intestinal epithelial deletion of Atg7 were generated and investigated in differentmouse models. Knockoutmice showed reduced size of granules and decreased levels of lysozyme in Paneth cells. However, this was dispensable for gut immune homeostasis and had no effect on susceptibility in mouse models of experimentally induced colitis. [ABSTRACT FROM AUTHOR]

Intervention of the gut microbiome is a promising adjuvant strategy in cancer immunotherapy. Chemotherapeutic agents are recognized for their substantial impacts on the gut microbiome, yet their therapeutic potential as microbiome modulators remains uncertain, due to the complexity of microbiome‐host‐drug interactions. Here, it is showed that low‐dose chemotherapy preferentially shapes the ileal microbiome to augment the extraintestinal immune response to anti‐programmed death‐1 (anti‐PD‐1) therapy without causing intestinal toxicity. Mechanistically, low‐dose chemotherapy causes DNA damage restricted to highly‐proliferative ileal epithelial cells, resulting in the accumulation of cytosolic dsDNA and the activation of the absent in melanoma 2 (AIM2) inflammasome. AIM2‐dependent IL‐18 secretion triggers the interplay between proximal Th1 cells and Paneth cells in ileal crypts, impairing the local antimicrobial host defense and resulting in ileal microbiome change. Intestinal epithelium‐specific knockout of AIM2 in mice significantly attenuates CPT‐11‐caused IL‐18 secretion, Paneth cell dysfunction, and ileal microbiome alteration. Moreover, AIM2 deficiency in mice or antibiotic microbial depletion attenuates chemotherapy‐augmented antitumor responses to anti‐PD1 therapy. Collectively, these findings provide mechanistic insights into how chemotherapy‐induced genomic stress is transduced to gut microbiome change and support the rationale of applying low‐dose chemotherapy as a promising adjuvant strategy in cancer immunotherapy with minimal toxicity. [ABSTRACT FROM AUTHOR]