Paneth cell granule of mouse intestine

The Muc2 mucin coats murine Paneth cell granules and facilitates their content release and dispersion

Paneth cells are a key subset of secretory epithelial cells found at the base of small intestinal crypts. Unlike intestinal goblet cells, which secrete the mucin Muc2, Paneth cells are best known for producing an array of antimicrobial factors. We unexpectedly identified Muc2 staining localized around Paneth cell granules. Electron microscopy (EM) confirmed an electron lucent halo around these granules, which was lost in Paneth cells from Muc2-deficient (^-/-) mice. EM and immunostaining for lysozyme revealed that Muc2^-/- Paneth cells contained larger, more densely packed granules within their cytoplasm, and we detected defects in the transcription of key antimicrobial genes in the ileal tissues of Muc2^-/- mice. Enteroids derived from the small intestine of wild-type and Muc2^-/- mice revealed phenotypic differences in Paneth cells similar to those seen in vivo. Moreover, lysozyme-containing granule release from Muc2^-/- enteroid Paneth cells was shown to be impaired. Surprisingly, Paneth cells within human ileal and duodenal tissues were found to be Muc2 negative. Thus Muc2 plays an important role in murine Paneth cells, suggesting links in function with goblet cells; however human Paneth cells lack Muc2, highlighting that caution should be applied when linking murine to human Paneth cell functions. NEW & NOTEWORTHY We demonstrate for the first time that murine Paneth cell granules possess a halo comprised of the mucin Muc2. The presence of Muc2 exerts an impact on Paneth cell granule size and number and facilitates the release and dispersal of antimicrobials into the mucus layer. Interestingly, despite the importance of Muc2 in murine Paneth cell function, our analysis of Muc2 in human intestinal tissues revealed no trace of Muc2 expression by human Paneth cells.

Mice deficient in N-acetylgalactosamine 4-sulfate 6-o-sulfotransferase are unable to synthesize chondroitin/dermatan sulfate containing N-acetylgalactosamine 4,6-bissulfate residues and exhibit decreased protease activity in bone marrow-derived mast cells

Chondroitin sulfate (CS) and dermatan sulfate (DS) containing N-acetylgalactosamine 4,6-bissulfate (GalNAc(4,6-SO(4))) show various physiological activities through interacting with numerous functional proteins. N-Acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST) transfers sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 6 of N-acetylgalactosamine 4-sulfate in CS or DS to yield GalNAc(4,6-SO(4)) residues. We here report generation of transgenic mice that lack GalNAc4S-6ST. GalNAc4S-6ST-null mice were born normally and fertile. In GalNAc4S-6ST-null mice, GalNAc(4,6-SO(4)) residues in CS and DS disappeared completely, indicating that GalNAc4S-6ST should be a sole enzyme responsible for the synthesis of GalNAc(4,6-SO(4)) residues in both CS and DS. IdoA-GalNAc(4,6-SO(4)) units that account for approximately 40% of total disaccharide units of DS in the liver of the wild-type mice disappeared in the liver DS of GalNAc4S-6ST-null mice without reduction of IdoA content. Bone marrow-derived mast cells (BMMCs) derived from GalNAc4S-6ST-null mice contained CS without GlcA-GalNAc(4,6-SO(4)) units. Tryptase and carboxypeptidase A activities of BMMCs derived from GalNAc4S-6ST-null mice were lower than those activities of BMMCs derived from wild-type mice, although mRNA expression of these mast cell proteases was not altered. Disaccharide compositions of heparan sulfate/heparin contained in the mast cells derived from BMMCs in the presence of stem cell factor were much different from those of heparan sulfate/heparin in BMMCs but did not differ significantly between wild-type mice and GalNAc4S-6ST-null mice. These observations suggest that CS containing GalNAc(4,6-SO(4)) residues in BMMCs may contribute to retain the active proteases in the granules of BMMCs but not for the maturation of BMMCs into connective tissue-type mast cells.

Lkb1 deficiency alters goblet and paneth cell differentiation in the small intestine

The Lkb1 tumour suppressor is a multitasking kinase participating in a range of physiological processes. We have determined the impact of Lkb1 deficiency on intestinal homeostasis, particularly focussing on secretory cell differentiation and development since we observe strong expression of Lkb1 in normal small intestine Paneth and goblet cells. We crossed mice bearing an Lkb1 allele flanked with LoxP sites with those carrying a Cyp1a1-specific inducible Cre recombinase. Lkb1 was efficiently deleted from the epithelial cells of the mouse intestine after intraperitoneal injection of the inducing agent beta-naphthoflavone. Bi-allelic loss of Lkb1 led to the perturbed development of Paneth and goblet cell lineages. These changes were characterised by the lack of Delta ligand expression in Lkb1-deficient secretory cells and a significant increase in the levels of the downstream Notch signalling effector Hes5 but not Hes1. Our data show that Lkb1 is required for the normal differentiation of secretory cell lineages within the intestine, and that Lkb1 deficiency modulates Notch signalling modulation in post-mitotic cells.

Defensins and Paneth cells in inflammatory bowel disease

Defensins are antimicrobial peptides produced by professional phagocytes, Paneth cells, and intestinal epithelial cells. In addition to their potent antimicrobial activity, defensins can also modulate the function and movement of neutrophils, monocytes, T-lymphocytes, dendritic cells, and epithelial cells. Paneth cells are equipped with multiple defensins and antimicrobial proteins and usually reside in the small intestine. This review highlights the diverse functions of defensins and changes in defensin expression and Paneth cell proliferation in Crohn's disease, ulcerative colitis, and animal models of inflammatory bowel disease. Current data favor the hypothesis that defensins and Paneth cells may play important roles in the maintenance of intestinal immune homeostasis through 2 distinct mechanisms. The first mechanism is to act as effector molecules and cells against pathogenic microbes, while the second is to regulate host immune cell functions.

A morphological study of the enteric mucosal epithelium in the streptozotocin-diabetic mouse

In the acutely diabetic rat, the polyphagia-induced increase in the weight of the small intestine is associated with reported increases in mucosal mass. Whereas, some of the individual mucosal components in the rat have been studied, comparable information for the acutely streptozotocin-diabetic mouse is lacking. A detailed morphological comparison of the epithelium of the small intestinal mucosa in control and untreated streptozotocin-diabetic mice was therefore undertaken. Samples from three small intestinal sites were examined by light and scanning electron microscopy and quantitative data obtained from histological sections. Although the morphological appearance of the small intestine in acutely diabetic mice was similar in many respects to literature accounts for the diabetic rat, infestation with filamentous microorganisms was present in the jejunum and ileum. The quantitative data showed that these sites also contained distorted villi, fewer crypt profiles, more goblet and Paneth cell profiles and a smaller epithelial volume in comparison to controls. These findings may represent differences between the rat and mouse models of streptozotocin-induced diabetes mellitus.

N- and O-linked oligosaccharides in the secretory granules of rat Paneth cells: an ultrastructural cytochemical study

Paneth cells are located at the base of the intestinal glands. The origin, composition, and function of these cells have not been well established. The sharing of a common pathway of development with the goblet cells has been suggested. The aim of the present study was to explore the cytochemical composition of rat Paneth cells and to discuss a possible developmental relationship between goblet and Paneth cells. Lectins (WGA, LTA, UEA-1, AAA, and HPA) were used as a precise tool for the ultrastructural localization of carbohydrates. Several procedures were performed in combination with lectin cytochemistry: beta-elimination, a reaction that specifically removes O-linked oligosaccharides (typical of mucin-type glycoproteins of goblet cells); and treatment with peptide N-glycosidase F, an enzyme that removes N-linked oligosaccharides from glycoproteins. Secretory granules of Paneth cells showed a biphasic nature composed of an electron-lucent peripheral halo containing O-linked oligosaccharides with GalNAc and GlcNAc residues and N-linked oligosaccharides with GlcNAc residues (only sparse Fuc residues were scarcely identified in O-linked oligosaccharides), and an electron-dense core containing N- and O-linked oligosaccharides with Fuc residues. Neither GlcNAc nor GalNAc was identified. The occurrence of O-linked oligosaccharides in the Paneth cells and the biphasic nature of the secretory granules, similar to that of transitional cells intermediate between mucous and serous cells of other tissues, favor the hypothesis of a common lineage for goblet and Paneth cells.

AN ELECTRON MICROSCOPE STUDY OF MATURE AND DIFFERENTIATING PANETH CELLS IN THE RAT, ESPECIALLY OF THEIR ENDOPLASMIC RETICULUM AND LYSOSOMES

In an electron microsope study, the morphology of mature Paneth cells from the small intestine of adult rats is compared with that of differentiating Paneth cells from young rats 2 to 4 weeks old. All mature cells exhibit a marked polarity similar to that of other exocrine gland cells and contain a well developed endoplasmic reticulum, an elaborate Golgi complex, and numerous large secretory granules; they also possess an abundance of lysosomes. The most conspicuous occurrence in the process of differentiation is the development of the endoplasmic reticulum. The most immature Paneth cells possess an endoplasmic reticulum of the vesicular type, which, during maturation, is replaced by the characteristic lamellated ergastoplasm of the mature cell. At a certain stage of differentiation the cavities of the developing cisternae show numerous communications with the perinuclear space, suggesting an outgrowth of the ergastoplasm from the nuclear envelope. Furthermore, the cavities and the perinuclear space at this particular stage contain a material which shows a remarkable intrinsic periodicity. An identical periodicity was exhibited by material contained in Golgi cisternae and secretory granules. Lysosomes are also present in the differentiating cells.

Echinostoma caproni and E. trivolvis alter the binding of glycoconjugates in the intestinal mucosa of C3H mice as determined by lectin histochemistry

Mouse (C3H) mucosal glycoconjugates were examined in normal small intestines and intestines infected with Echinostoma caproni or E. trivolvis using six different fluorescein-conjugated lectins: Triticum vulgaris agglutinin (WGA), Ulex europaeus agglutinin I (UEA-I), Ricinus communis agglutinin I (RCA-I), Glycine max soybean agglutinin (SBA), Dolichos biflorus agglutinin (DBA), and Arachis hypogaea peanut agglutinin (PNA). The expression of lectin-binding sites and the intensity of the binding of lectins in the mouse small intestines were changed by infection with the echinostomes. Specific differences in the reaction to glycoproteins were clearly observed between the mouse intestines infected with E. caproni and those infected with E. trivolvis. In E. caproni infection, binding of most of the lectins to the villi was remarkably reduced in accord with the villous atrophy and loss of goblet cells. In contrast, in E. trivolvis infection, the binding of WGA, RCA-I and DBA was reduced in the microvillar surfaces, but binding of UEA-I and SBA were unchanged compared to the control intestines. The lectin binding to goblet cells in E. trivolvis-infected mice mostly increased. These observations may reflect the marked increase in goblet cells and the less severe damage in the villi of E. trivolvis infection compared to E. caproni infection. Most of the glycoconjugates were slightly reduced in the hyperplastic crypts except for N-acetyl glucosamine. It is possible that glucose metabolism in the host intestines infected with E. trivolvis was activated, resulting in an increase in the rate of mucin synthesis as well as qualitative changes in mucus, thereby mediating the expulsion of the worms.

Presence and ontogeny of intestinal and pancreatic phospholipase A2-like proteins in the Red Sea bream,Pagrus major. An immunocytochemical study

We have studied the location and the ontogeny of the digestive enzyme, phospholipase A2 (PLA2) immunohistochemically in the adult and larvae/juvenile of the red sea breamPagrus major by using an antiserum against theNaja naja venom PLA2. The antiserum reacts with at least one enzyme among the PLA2s purified from the fish hepatopancreas or intestine. Although the reactivities were comparatively low, it labelled zymogen granules of the pancreatic acinar cells and secretory materials of certain epithelial cells in the depths of epithelial crypts in the pyloric caeca of the adult. The immunoreactivities of PLA2s were investigated in the viscera of larvae and juveniles of the 0 to 85(th) day after hatch. In the larvae of the 13(th) day, accumulation of PLA2-positive zymogen granules in the pancreatic acinar cells were first recognized by the immunostaining. The intensity of the labelling subsequently became stronger and dramatically increased between the 20(th) and 30(th) day. This increase appeared to be one of the physiological changes associated with the transition to a new benthic life as juveniles. Lack of PLA2 in the pancreas before the 13(th) day may suggest the possibility that larvae utilized exogenous PLA2, inherent in their prey, to digest the phospholipids. On the other hand, no reactivity was found in the intestine until the 85(th) day.

Ultrastructure of Paneth cells in the intestine of various mammals

Paneth cells in the following species were observed under an electron microscope: human, rhesus monkey, hare, guinea pig, rat, nude rat, mouse, golden hamster, and insect feeder bat. Secretory granules containing homogeneous electron-dense materials were observed in the Paneth cells of humans, monkeys, hares, guinea pigs, and bats; mouse Paneth-cell granules were bipartite (central core and peripheral halo), and the Paneth cells in rats and golden hamsters had secretory granules showing various electron densities. In humans, monkeys, and bats, immature granules near the Golgi apparatus sometimes showed bipartite substructure. The number and size of secretory granules were also diverse among various animal species. Some lysosome-like bodies were commonly observed in peri- or supranuclear regions, though the size and shape of the bodies differed from cell to cell. In apical cytoplasm, small clear vesicles (100-200 nm diameter) were more-or-less observed in all species examined, and it was especially note that rat Paneth cells contained many clear vesicles. Small dense-cored vesicles (150-200 nm diameter) were rare. It is unlikely that the various ultrastructural features of Paneth cells correlate with the phylogenetical classification.

Effects of cholecystokinin and carbamylcholine on Paneth cell secretion in mice: a comparison with pancreatic acinar cells

To confirm whether the Paneth cells of mice (ICR, male, 10-12 weeks old) have the same secretory response to hormonal and cholinergic stimulation as do pancreatic acinar cells, ultrastructural changes of Paneth cells and pancreatic acinar cells 1 hr after administration of various doses of cholecystokinin (octapeptide, CCK-8) and carbamylcholine were morphometrically assessed. After maximal (1.5 micrograms/kg intraperitoneally [i.p.]) and supramaximal (15 micrograms/kg, i.p.) stimulation by CCK-8, pancreatic acinar cells showed, respectively, degranulation or disturbance of secretion (e.g., an increase in lysosome-like bodies, aggregation of zymogen granules). The Paneth cells, however, were almost unchanged in the parameters examined. After carbamylcholine injection (1,000 micrograms/kg, subcutaneously [s.c.]), both pancreatic acinar cells and Paneth cells showed degranulation. Paneth cells sometimes developed large vacuoles, probably formed after massive exocytosis; such vacuoles were not observed in pancreatic acinar cells. It is suggested that Paneth cells and pancreatic acinar cells have different secretory responses. Paneth cell secretion, which possibly plays a role in controlling the intestinal bacterial milieu, may be stimulated by cholinergic rather than hormonal mechanisms.

Atropine inhibits the degranulation of Paneth cells in ex-germ-free mice

Previous studies have shown that the secretory products of Paneth cells contain antibacterial agents (lysozyme, IgA) that are affected by the bacterial milieu in the intestine. To investigate whether Paneth-cell secretion is controlled via cholinergic mechanisms, the ultrastructure of Paneth cells was studied in four animal groups: (1) germ-free (GF) control mice (Jcl: ICR [GN], male, 13 weeks old), (2) GF mice injected subcutaneously with atropine sulfate (200 mg/kg body weight, dissolved in physiological saline 20 mg/ml), (3) ex-GF mice inoculated with feces from specific-pathogen-free (SPF) mice, and (4) ex-GF mice injected with atropine and inoculated with feces from SPF mice. In ex-GF mice inoculated with feces, 70-90% of the Paneth cells showed fewer secretory granules than those from GF mice (p less than 0.01). Approximately 30% of the Paneth cells had a large vacuole (3-10 micron diameter) in the apical cytoplasm. Exocytosed electron-dense material from secretory granules was observed in a few crypt lumens. In ex-GF mice inoculated with feces and given atropine, about 90% of the Paneth cells contained numerous secretory granules, like those in GF control mice, but vacuolated Paneth cells and exocytotic figures were rare; thus the secretion of Paneth cells was blocked by atropine. It is therefore possible that the bacterial milieu in the intestine affects the secretory activity of Paneth cells via cholinergic mechanisms.

Effect of live and heat-killed bacteria on the secretory activity of Paneth cells in germ-free mice

Germ-free mice were given live or heat-killed facultative anaerobes, and the ultrastructure of ileal Paneth cells was quantitatively examined with special reference to secretory granules showing a bipartite substructure (central core and peripheral halo). After administering live or heat-killed bacteria, there was a decrease in the area occupied by the cores of secretory granules in Paneth cells, and exocytosed core material was observed in the crypt lumen. There were no changes in the area occupied by the halo of secretory granules. None of the examined Paneth cells phagocytosed bacteria. It is concluded that certain bacteria may affect the secretion of antibacterial agents contained in the secretory granules of Paneth cells.

Immunohistochemical observations of lysozyme in the Paneth cells of specific-pathogen-free and germ-free mice

The localization of lysozyme, which may function as an antibacterial agent, was immunohistochemically studied on the mouse Paneth cell secretory granules showing bipartite substructures (central core and peripheral halo). The lysozyme immunoreactivity was observed in the core, but not in the halo. Even in germ-free mice, Paneth cells have many secretory granules and their cores show lysozyme immunoreactivity. It seems likely that mice Paneth cells possess the ability to produce secretory granules containing lysozyme in disregard of the intestinal bacterial milieu.

Ultrastructural changes in Paneth cells during hibernation in the ground squirrel Spermophilus lateralis

The ultrastructure of Paneth cells from jejuno-ileal segments of the small intestine of the ground squirrel, S. lateralis, was examined under normal euthermic conditions and during the profoundly depressed metabolic conditions of natural hibernation. Paneth cells obtained from hibernating animals gave evidence of markedly reduced activity when compared to Paneth cells from euthermic animals. In hibernating animals, the nuclei were smaller, with less prominent nucleoli and with an increased proportion of heterochromatin, In hibernating animals, the rough endoplasmic reticulum was fragmentary and poorly organized, in contrast to the typical arrangement of concentric lamellae seen in euthermic animals. Although the total number of ribosomes was decreased in hibernating animals, there were proportionally more free ribosomes than in euthermic animals. Paneth cells from hibernating animals also contained a greater number of apical secretory granules which were smaller and more variable in electron density than granules from control animals. These ultrastructural features indicate that during hibernation the Paneth cell is relatively quiescent.

New observations of rat airway epithelium: a quantitative and electron microscopic study

Epithelial thickness, depth of the ciliary layer and concentration of cells has been estimated at 5 levels of the rat airway (3 extrapulmonary and 2 intrapulmonary) and the ultrastructure of the cells described. Extrapulmonary airways have a pseudostratified epithelium, intrapulmonary airways a simple one. The epithelium thins progressively from upper to lower trachea while the epithelium of the lower trachea is thicker than at more peripheral airway levels, all of which are similar. The depth of the ciliary layer decreases peripherally. By electron microscopy 10 cell types could be identified - 8 epithelial and 2 'migratory'. A cell type not described previously has been found that resembles the serous cells of the submucosal glands. The salient features of each cell type are described. The upper trachea has a concentration of cells significantly higher than elsewhere, while the remaining four airway levels have about 230 cells per 10 high power fields (1-8 mm length epithelium). Ciliated cells are sparse proximally and increase in number progressively toward the periphery, while basal and migratory cells are most frequent proximally. At all levels of the airway, between 40% and 50% of cells are non-ciliated. In the upper trachea the most frequent cell type was the 'intermediate', elsewhere the 'epithelial serous' cell. Goblet cells were few at all levels, amounting to less than 1% of the total counted. The Clara cell was not restricted to the terminal bronchioles but was found as far proximally as the hilum.

Effects of glucagon and insulin on the Paneth cells of the mouse duodenum

The effect of glucagon and insulin on the paneth cells (PC) of the duodenum of the mouse was investigated using light microscopy. Both glucagon and insulin were able to increase significantly the number of the secretory granules of PC. This possibly means that these hormones are capable of inhibiting the secretion of PC.