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The cytokine tumor necrosis factor (TNF) plays important roles in limiting infection but is also linked to sepsis. The mechanisms underlying these paradoxical roles are unclear. Here, we show that TNF limits the antimicrobial activity of Paneth cells (PCs), causing bacterial translocation from the gut to various organs. This TNF-induced lethality does not occur in mice with a PC-specific deletion in the TNF receptor, P55. In PCs, TNF stimulates the IFN pathway and ablates the steady-state unfolded protein response (UPR), effects not observed in mice lacking P55 or IFNAR1. TNF triggers the transcriptional downregulation of IRE1 key genes Ern1 and Ern2 , which are key mediators of the UPR. This UPR deficiency causes a significant reduction in antimicrobial peptide production and PC antimicrobial activity, causing bacterial translocation to organs and subsequent polymicrobial sepsis, organ failure, and death. This study highlights the roles of PCs in bacterial control and therapeutic targets for sepsis. [Display omitted] • PC-specific TNFR1 (P55) mutant mice are protected against lethal TNF effects • PC-P55 signaling triggers an interferon signature and UPR failure in these cells • This UPR failure in PCs is IFNAR1 and P55 dependent but microbiome independent • PC-P55 UPR failure reduces AMP activity, causing bacterial escape and sepsis Wallaeys et al. studied Paneth cells (PCs) during TNF-induced inflammation. TNF signaling through its P55 receptor on PCs triggers an interferon signature and disrupts the unfolded protein response, causing reduced production of antimicrobial peptides and decreased antimicrobial activity. This PC dysfunction causes gut bacterial translocation and sepsis. [ABSTRACT FROM AUTHOR]

Paneth cells located within intestinal crypts support epithelial stem cells and immunity through growth factors and antimicrobial peptides. In this issue of Cell Host & Microbe , Wallaeys et al. report that TNF sensing by Paneth cells disrupts the unfolded protein response and decreases antimicrobial peptides, causing bacterial translocation and sepsis. [ABSTRACT FROM AUTHOR]

Vitamin D exerts a regulatory role over mucosal immunity via the vitamin D receptor (VDR). Although Paneth cells and their products are known to regulate the commensal and pathogenic microbiota, the role that VDRs in Paneth cells play in these responses is unknown. We identified the decreased intestinal VDR significantly correlated with reduction of an inflammatory bowel disease risk gene ATG16L1 and Paneth cell lysozymes in patients with Crohn's disease. We generated Paneth cell–specific VDR knockout (VDRΔPC) mice to investigate the molecular mechanisms. Lysozymes in the Paneth cells were significantly decreased in the VDRΔPC mice. Isolated VDRΔPC Paneth cells exhibited weakened inhibition of pathogenic bacterial growth and displayed reduced autophagic responses. VDRΔPC mice had significantly higher inflammation after Salmonella infections. VDRΔPC mice also showed high susceptibility to small intestinal injury induced by indomethacin, a nonsteroidal anti-inflammatory drug. Co-housing of VDRΔPC and VDRlox mice made the VDRΔPC less vulnerable to dextran sulfate sodium colitis, suggesting the transmission of protective bacterial from the VDRlox mice. Thus, a lack of VDR in Paneth cells leads to impaired antibacterial activities and consequently increased inflammatory responses. Genetically and environmentally regulated VDRs in the Paneth cells may set the threshold for the development of chronic inflammation, as observed in inflammatory bowel diseases. We provide new insights into the tissue-specific functions of VDRs in maintaining Paneth cell alertness to pathogens in intestinal disorders. Targeting the VDR affects multiple downstream events within Paneth cells that inhibit intestinal inflammation and establish host defense against enteropathogens. [Display omitted] [ABSTRACT FROM AUTHOR]

• Colonic Paneth adenocarcinoma is a rare entity with only a few reports in the world literature. • The pathologist must be aware of the existence of this histological subtype. • A specific pathogen pathway is incriminated. • The treatment remains equal to other classic types of colorectal adenocarcinoma. Amongst the morphotypes of colorectal adenocarcinomas, the rich cell type of Paneth constitutes a rare histopathologic variant of adenocarcinoma, which can be observed all along the digestive tract but also in other organs such as the prostate or the breast. About 24 cases were found in the literature, with only 7 cases within the colon and appendix. We report the case of a 50-year-old man, without past medical history, complaining of abdominal pain and constipation for 3 months. Biological tests were normal. Radiological investigations and endoscopy revealed a sessile polyp in the right colonic angle measuring 4 cm in greatest diameter. Biopsy concluded to a tubular adenoma with low-grade dysplasia. The patient underwent right hemicolectomy. Microscopically, an invasive adenocarcinoma was identified occupying the colonic mucosal with an invasion of the submucosa. The tumor showed a tubulovillous pattern on the surface and was made mostly of jagged crowded glands in the depth. Some areas exhibit Paneth cell differentiation. No metastatic lymph node was found, and the tumor was staged T1N0. The postoperative course was uneventful. The patient remained free of symptoms at the 6-month follow-up and had no evidence of recurrence. We reported a Tunisian case of Paneth cell colonic adenocarcinoma. The diagnosis is challenging in biopsies when only well-differentiated areas are sampled. Lysozyme immune-histochemical stain may be helpful when diagnosis difficulty arises. The beta-catenin pathway seems to be activated. More studies are needed for the etiology, pathogenesis, clinical course, prognosis and treatment of Paneth cell carcinoma. [ABSTRACT FROM AUTHOR]

Necrotizing enterocolitis is associated with decreased intestinal perfusion and ischemia. Paneth cells, specialized epithelial cells, have been shown to regulate the intestinal vasculature and disruption of these cells has been associated with NEC. We hypothesized that Paneth cell disruption in immature mice intestine would decrease the perfusion of the intestinal microvasculature. Paneth cells were disrupted in P14–16 mice using chemical (dithizone) and transgenic (diphtheria toxin) methodology. Six hours after Paneth cell disruption, Dylight 488 was injected directly into the left ventricle and allowed to perfuse for 5 minutes prior to intestinal harvesting. Tissue samples were evaluated with confocal fluorescence microscopy to quantify intestinal perfusion and samples were quantified by real time RT-PCR for gene expression. Dithizone treatment significantly decreased intestinal perfusion compared to controls (p < 0.01). However, diphtheria toxin treatment demonstrated no significant difference in perfusion (p > 0.21). Intestines from all treatment groups had similar PECAM staining, but intestines treated with dithizone had significantly decreased nNOS and iNOS gene expression compared to controls (p < 0.007). Paneth cell disruption significantly decreases the perfusion of the small intestinal microvasculature in a dithizone-specific manner. Dithizone has no effect on the amount of microvasculature, but does impact genes critical to nitric oxide signaling likely contributing to mesenteric vasoconstriction. [ABSTRACT FROM AUTHOR]

Paneth cells secrete antimicrobial proteins including lysozyme via secretory autophagy as part of the mucosal protective response. The ELAV like RNA-binding protein 1 (ELAVL1, also called HuR) regulates stability and translation of messenger RNAs (mRNAs) and many aspects of mucosal physiology. We studied the posttranscriptional mechanisms by which HuR regulates Paneth cell function. Intestinal mucosal tissues were collected from mice with intestinal epithelium (IE)-specific disruption of HuR (IE- HuR –/–), HuR fl/fl-Cre– mice (controls), and patients with inflammatory bowel diseases and analyzed by histology and immunohistochemistry. Paneth cell functions were determined by lysozyme-immunostaining assays. We isolated primary enterocytes from IE- HuR –/– and control mice and derived intestinal organoids. HuR and the chaperone CNPY3 were overexpressed from transgenes in intestinal epithelial cells (IECs) or knocked down with small interfering RNAs. We performed RNA pulldown assays to investigate interactions between HuR and its target mRNAs. Intestinal tissues from IE- HuR –/– mice had reduced numbers of Paneth cells, and Paneth cells had fewer lysozyme granules per cell, compared with tissues from control mice, but there were no effects on Goblet cells or enterocytes. Intestinal mucosa from patients with inflammatory bowel diseases had reduced levels of HuR and fewer Paneth cells. IE- HuR –/– mice did not have the apical distribution of TLR2 in the intestinal mucosa as observed in control mice. IECs from IE- HuR –/– mice expressed lower levels of CNPY3. Intestinal organoids from IE- HuR –/– mice were smaller and contained fewer buds compared with those generated from controls, and had fewer lysozyme-positive cells. In IECs, knockdown of HuR decreased levels of the autophagy proteins LC3-I and LC3-II, compared with control cells, and prevented rapamycin-induced autophagy. We found HuR to interact directly with the Cnpy3 mRNA coding region and increase levels of CNPY3 by increasing the stability and translation of Cnpy3 mRNA. CNPY3 bound TLR2, and cells with knockdown of CNPY3 or HuR lost membrane localization of TLR2, but increased cytoplasmic levels of TLR2. In studies of mice, IECs, and human tissues, we found HuR to increase expression of CNPY3 at the posttranscriptional level. CNPY3 is required for membrane localization of TLR2 and Paneth cell function. [ABSTRACT FROM AUTHOR]

Clear cell renal cell carcinoma (CRCC) is well known for its intratumoral heterogeneity. Paneth-like cells (PLC) have been reported in variable organs (i.e., hepatobiliary, genitourinary, and female genital tract). In genitourinary system, it is possible to find PLCs in epididymis, urinary bladder and prostate. The objective of this study was to assess PLC in CRCCs 13 CRCCs with prominent PLC (CRCCPLC) were selected out of 1378 CRCCs in our registry. The tumors were analyzed using morphologic, immunohistochemical, ultrastructural, and molecular genetic methods. CRCCPLCs were mostly of low histologic grade (12/13). Immunohistochemical profile was compatible with classic CRCC. PLC constituted 10 to–70% of the tumor volume (mean 17.7%, median 10%). PLCs did not express neuroendocrine markers (chromogranin, synaptophysin, CD56, INSM-1). Ultrastructurally, PLCs were filled by membrane bounded vesicles of various sizes and were compatible with secretory type of cells. VHL mutation was found in 9/9 cases, and LOH3p was found in 6/8 analyzable cases. Conclusions: PLC morphology can variably be present in "classic" CRCC, even in a substantial proportion. Ultrastructurally, PLCs have all attributes of secretory cells. Preliminary follow up data showed that these tumors may not be associated with aggressive clinical behavior. • Paneth-like cells were reported in variable organs. • We assessed PLC in clear cell renal cell carcinomas. • 13 CRCCs with prominent PLC were selected. • Ultrastructurally, PLCs have attributes of secretory cells. • Follow up data indicated non-aggressive behavior. [ABSTRACT FROM AUTHOR]

Deoxynivalenol (DON) is a common toxin in grains and feeds, and DON exposure triggers severe small intestinal injury and inflammation, which harms the health of humans and livestock. DON treatment leads to a decrease in Paneth cells, whereas the role of Paneth cells in DON-induced intestinal injury is poorly understood. We utilized dithizone (40 mg/kg) to keep murine Paneth cell number at a low level. The results showed that dithizone-mediated long-term disruption of Paneth cells aggravated intestinal injury, intestinal stem cell (ISC) loss, and microbiota disorder in DON (2 mg/kg)-treated mice. Unexpectedly, the number of goblet cells and proliferative cells was boosted in mice treated with dithizone and DON. After dithizone and DON treatments, the Firmicutes / Bacteroidetes (F/B) ratio was reduced, and the increased abundance of Dubosiella and the decreased abundance of Lactobacillus were observed in mice. The functional recovery of Paneth cells by lysozyme (200 U/day) supplementation improved intestinal injury and ISC loss in mice after DON challenge. In addition, lysozyme also promoted the growth and ISC activity of intestinal organoids. Taken together, these results demonstrate the protective role of Paneth cells in DON-induced intestinal injury. Our study raises a novel target, Paneth cell, for the treatment of DON exposure. [Display omitted] • Dithizone-induced Paneth cell disruption aggravates DON-induced jejunal injury. • Paneth cell disruption aggravates DON-induced stem cell loss and microbiota disorder. • Lysozyme ameliorates dithizone + DON-induced jejunal injury and inflammation. • Lysozyme protects stem cell niche from DON challenge in intestinal organoids. [ABSTRACT FROM AUTHOR]

Pathogenesis of Crohn’s disease (CD) involves immune and microbial dysregulation, induced by environmental factors in genetically susceptible individuals. There are believed to be multiple subtypes of CD, which contributes to its observed clinical heterogeneity. This concept has been reinforced by recognition of the complexity of the genetic, microbial, immune, and environmental factors that affect risk for CD. Paneth cells mediate immunity and maintain the small intestinal epithelium; defects in activities of these cells have been observed in high proportions of patients with CD, and are associated with a more aggressive CD phenotype. Paneth cells integrate complex genetic, immune, and environmental signals, therefore alterations in their function could lead to different subtypes of CD, as observed in studies in cohorts of primarily European descent. Subtypes of CD associated with Paneth cell function have been observed even among patients from different genetic backgrounds. We discuss genetic susceptibility loci for CD and how these affect Paneth cell activity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Gastrointestinal mucositis (GIM), induced by chemotherapy, is associated with alterations in the function of the intestinal barrier due to the potential damage induced by anti-cancer drugs on the epithelial cells. The Paneth cells, an important epithelial lineage in the intestine, contribute to the innate immunity by releasing antimicrobial proteins onto the mucosal surfaces. Polysaccharide, as a widely used immunomodulatory nutrient, was reported to have an effect of modulating the intestinal immune system. However, the effect of dietary polysaccharides in protecting the Paneth cells from injuries induced by chemotherapy was poorly investigated. In the current study, with a mouse model of cyclophosphamide (Cy)-induced gastrointestinal injury, the polysaccharide extracted from the ink of Ommastrephes bartrami (OBP) were found to protect the mouse Paneth cells from chemotherapeutic injury. Ommastrephes bartrami polysaccharide (OBP) treatment could enhance the mRNA expression of antimicrobial proteins in the Paneth cells, such as lysozyme, Ang4, Defa-5, and sPLA 2 . The increased production of the microbicidal proteins in the Paneth cells was dependent on the relatively highly developed endoplasmic reticulum (ER) structure but was not dependent on the increase in the quantity of the ER. The Ommastrephes bartrami polysaccharide (OBP) activated the IRE-1 mediated XBP-1s pathway to cope with antimicrobial protein secretion. Our results may have important implications with regard to the role of OBP in chemotherapy-induced Paneth cell injury in intestinal disorders involving inflammation and infection. [ABSTRACT FROM AUTHOR]

Background & Aims: Genetic susceptibility loci for Crohn's disease (CD) are numerous, complex, and likely interact with undefined components of the environment. It has been a challenge to link the effects of particular loci to phenotypes of cells associated with pathogenesis of CD, such as Paneth cells. We investigated whether specific phenotypes of Paneth cells associated with particular genetic susceptibility loci can be used to define specific subtypes of CD. Methods: We performed a retrospective analysis of 119 resection specimens collected from patients with CD at 2 separate medical centers. Paneth cell phenotypes were classified as normal or abnormal (with disordered, diminished, diffuse, or excluded granule phenotypes) based on lysozyme-positive secretory granule morphology. To uncover the molecular basis of the Paneth cell phenotypes, we developed methods to determine transcriptional profiles from whole-thickness and laser-capture microdissected, formalin-fixed, paraffin-embedded tissue sections. Results: The proportion of abnormal Paneth cells was associated with the number of CD-associated NOD2 risk alleles. The cumulative number of NOD2 and ATG16L1 risk alleles had an additive effect on the proportion of abnormal Paneth cells. Unsupervised clustering analysis of demographic and Paneth cell data divided patients into 2 principal subgroups, defined by high and low proportions of abnormal Paneth cells. The disordered and diffuse abnormal Paneth cell phenotypes were associated with an altered transcriptional signature of immune system activation. We observed an inverse correlation between abnormal Paneth cells and presence of granuloma. In addition, high proportions of abnormal Paneth cells were associated with shorter time to disease recurrence after surgery. Conclusions: Histologic analysis of Paneth cell phenotypes can be used to divide patients with CD into subgroups with distinct pathognomonic and clinical features. [Copyright &y& Elsevier]

Paneth cells in the small intestine are able to sense luminal bacteria and secrete granules that contain antibacterial peptides. Human defensin (HD)-5 and -6 are antimicrobial peptides found in human Paneth cell granules, and are major bactericidal components. We investigated whether any constituents in the Paneth cell secretions showed chemotactic activity or stimulated cytokine secretion from intestinal epithelial cells, and assessed to what extent HD-5 and -6 were responsible for these activities. The secretions from human Paneth cells and recombinant HD-5 and -6 were evaluated to elucidate their effects on the chemotaxis of dendritic cells (DCs) in a migration assay. The Paneth cell secretions were chemotactic for immature DCs at concentrations ranging from 10 to 1,000 µg/ml. HD-6 was active at 100 ng/ml, but HD-5 was not. Next, the stimulation of cytokine production by the T84 intestinal cell line was assessed using ELISA and/or an antibody array. The secretions more strongly stimulated interleukin (IL)-8 production than did the defensin peptides, and induced production of various cytokines by the antibody array. The secretions were also analyzed by high performance liquid chromatography (HPLC) and mass spectrometry (MS) in order to determine the components. A large number of molecules was found in the secretions, and HD-5 was identified as an immature propeptide. In conclusion, some constituents other than defensin in human Paneth cell secretions activated the migration of DCs and induced the production of inflammatory cytokines. Therefore, Paneth cells may play a role in the innate immunity associated with adaptive immune responses. [ABSTRACT FROM AUTHOR]

Summary: Paneth cell differentiation may occur in colonic epithelial neoplasms. However, its significance and mechanism of development remains unclear. Human defensin 5 is a specific marker of Paneth cells and has been shown to represent one of the target genes of the Apc/β-catenin/Tcf pathway. The aim of this study was to evaluate the frequency of Paneth cell differentiation in a variety of colonic neoplasms, and to investigate the role of human defensin 5 and β-catenin in this process. The clinical and pathologic findings, including histologic evidence of Paneth cell differentiation and immunostaining for human defensin 5 and β-catenin, were evaluated in 29 samples of nonneoplastic colonic mucosa, 18 hyperplastic polyps, 10 sessile serrated adenomas, 12 traditional serrated adenomas, 21 mixed polyps, 39 conventional adenomas, and 40 adenocarcinomas. Human defensin-5 and β-catenin expression were evaluated for the location and degree of staining in all cell types (dysplastic and nondysplastic) and correlated with histologic areas of Paneth cell differentiation in all types of polyps. Histologic evidence of Paneth cell differentiation was observed in 15 conventional adenomas (38.5%) and 1 adenocarcinoma (2.5%) but not in other types of polyps. Human defensin-5 immunostaining was positive in the cytoplasm of all nonneoplastic Paneth cells and all neoplastic cells with Paneth cell differentiation. Human defensin-5 expression was noted in 0% of hyperplastic polyps, 10% of sessile serrated adenomas, 25% of traditional serrated adenomas, 33.3% of mixed polyps, 82.1% of conventional adenomas, and 17.5% of adenocarcinomas: human defensin 5 expression was significantly higher in conventional adenomas compared to all other groups (P < .01). Seventeen (53.1%) of 32 human defensin 5 positive conventional adenomas, 6 (86%) of 7 of human defensin 5 positive adenocarcinomas, and all human defensin 5–positive sessile serrated adenomas, traditional serrated adenomas, and mixed polyps did not show histologic evidence of Paneth cell differentiation. All mixed polyps (100%) that revealed human defensin 5 expression (7; 33.3%) revealed conventional dysplasia. In the positive mixed polyp cases, human defensin 5 was only positive in areas of conventional dysplasia. Of the 31 conventional adenomas with nuclear β-catenin staining, 15 (48.4%) revealed histologic evidence of Paneth cell differentiation, and all of the neoplastic cells with Paneth cell differentiation showed nuclear β-catenin staining, whereas nonneoplastic Paneth cells consistently showed a normal pattern of membranous β-catenin staining. A strong topographical correlation was noted between human defensin 5 expression and nuclear β-catenin expression in conventional adenomas and in conventional dysplastic epithelium of mixed polyps. Paneth cell differentiation is common in early colonic neoplasms that develop via the conventional adenoma-carcinoma carcinogenic pathway. Activation of Apc/β-catenin/Tcf pathway may play a role in Paneth cell differentiation in human colonic neoplasms. [Copyright &y& Elsevier]