The transitional polyp of the colorectal mucosa

45 cases of small polypoid lesions occurring in the colorectal mucosa free of inflammatory or neoplastic disease are presented. The lesions were removed at colonoscopy and displayed neither features of hyperplastic (metaplastic) polyps nor features of a neoplastic proliferation. Morphologically these small lesions were characterized by elongated and widened crypts, enlarged goblet cells with an increase in mucous production. Histochemically there was a reversion of the usual pattern of mucin production in the colorectal mucosa: an increase in sialomucin production and a decrease in sulfomucins. Thus these lesions demonstrate the same morphological and histochemical features as the transitional mucosa surrounding carcinoma and adenoma in the large bowel. These "transitional" polyps could represent an early step in the development of neoplastic processes in the colorectal mucosa and precede adenomas.     

Concanavalin A binding sites in fetal, adult, transitional, and malignant rectosigmoid mucosa

We studied mucin histochemistry in 25 rectosigmoid adenocarcinomas and in the transitional mucosa adjacent to these tumors using standard techniques for the detection of neutral and acid sialomucins and sulfomucins and the paradoxical concanavalin A (Con A) stain. This histochemical procedure selectively detects residues of mannose in glycoproteins exposed to brief steps of oxidation and reduction. Those techniques were also used to study histologically normal mucosa of specimens with carcinoma, normal rectosigmoid mucosa of patients without inflammatory or neoplastic bowel disease, hyperplastic rectal polyps, and rectosigmoid mucosa of human fetuses. Normal mucosa and hyperplastic polyps mainly contained sulfomucins and did not display Con A binding activity with any of the variants of the stain. In contrast, fetal, transitional, and malignant mucosa predominantly showed sialomucins and although not reactive with the standard Con A sequence, displayed binding activity for the lectin after short oxidative-reductive steps. These results provide further evidence that transitional and malignant mucosa produce markedly abnormal mucins whose histochemical patterns represent a re-emergence of the fetal type found during development. The principles of the paradoxic Con A reaction may be applied to unmask lectin binding activity in apparently unreactive sites.     

Distribution and histochemical characterization of goblet cells in the nasal cavity of piglets

The present study was desiged to compare the distribution of goblet cells and the histochemical composition of mucosubstances produced by these cells in the nasal cavity of piglets aged from 1 to 28 days. Serial transverse sections were stained to demonstrate neutral, acidic, and sulfated mucosubstances. Sections located at eight reference levels rostrocaudally in the nasal cavity and defined regions on these sections were used for goblet-cell counting. There was a nonhomogeneous distribution of goblet cells in the nasal cavity of piglets. A rostrocaudal increase in goblet-cell density was observed with the highest densities found in the ventral meatus and on the septum. There was no difference in this pattern of distribution according to age of the piglets. However, age-related differences were observed in the prevalence of goblet cells containing sialomucins, sulfomucins, or both. While sialomucins were prevalent at 1 and 14 days, sulfomucins predominated in the rostral half of the cavity at 28 days. Our results indicate a maturation of the products of secretion with aging in piglets. The affinity of infectious agents for sialylated glycoconjugates and the predominance of sialomucins in the nasal cavity of newborn piglets could account for their greater susceptibility to bacterial infection.     

Abnormal patterns of colorectal mucin secretion after urinary diversion of different types: histochemical and lectin binding studies

Clinical and experimental evidence indicates that ureterosigmoidostomy is associated with a high risk for the development of colonic cancer, while there is no reported evidence of increased risk in patients who undergo urinary diversion of other types. In the present study the histochemical and lectin binding characteristics of goblet cell mucin were investigated in biopsy specimens from patients who had undergone ureterosigmoidostomy and from patients who had undergone rectal bladder surgery. Specimens from transitional mucosa surrounding colonic cancers and from normal rectal mucosa were also studied. For histochemical studies the high iron diamine-Alcian blue method was used. FITC-conjugated Dolichus biflorus agglutinin (FITC-DBA) and Arachis hypogaea agglutinin (FITC-PNA) were used for the study of lectin binding characteristics. In contrast to the striking increase in numbers of sialomucin-containing goblet cells found in the patients who had undergone ureterosigmoidostomy, the mucin proved to be histochemically normal in the rectal bladder surgery group. Abnormal lectin binding patterns were observed in colorectal mucosa after urinary diversion of both types, with the abnormalities consisting of dramatic decreases in FITC-DBA labeling (compared with controls) and the appearance of substantial numbers of FITC-PNA-labeled goblet cells. These findings indicate that the pattern of mucin secretion is definitely abnormal in patients who have undergone urinary diversion. Whether this abnormality is an indicator of premalignant changes remains to be established. These data, however, confirm that endoscopic and histologic follow-up studies may be of value in assessing the risk for the development of cancer in these patients.     

Patterns of mucin secretion in neoplastic and non-neoplastic diseases of the colon

Changes in the pattern of sulfomucin and sialomucin secretion and height of large bowel mucosa have been described adjacent to primary colonic adenocarcinomas and adenomas, and called “transitional” mucosa. These-changes were initially thought to be specific preneoplastic changes. In this study “transitional” changes in colonic and rectal mucosa were found in some cases overlying benign mesenchymal tumors, metastatic tumors from noncolonic sites, and sites of endometriosis, as well as adjacent to primary colonic and rectal neoplasms. These findings suggest that although these changes may be found adjacent to primary large bowel neoplasms, they are frequently secondary reactive rather than primary preneoplastic phenomena. In addition, the thickness of the mucosa and the accompanying pattern of mucin secretion usually seen in transitional mucosa may be dissociated.     

Structure of mucosa in continent ileal reservoirs 15 to 19 years after construction

Mucosa biopsy specimens were obtained from 12 patients with continent ileostomy reservoirs constructed 15 to 19 years previously. Biopsies from normal ileal mucosa, taken from six other patients with no apparent bowel disease, served as controls. The specimens were processed for light and electron microscopy. The reservoir mucosae showed an increased amount of inflammatory cells, but there were no signs of dysplasia. In the goblet cells, sialomucins dominated over sulfomucins; in this respect no difference was found between reservoirs and controls. Morphometric studies showed an increase of mucus-storing goblet cells in the reservoir mucosae, both with regard to relative number and to volume density. The mitotic index was higher than normal in the reservoirs, but the relative number of the Paneth cells and the height of the villus epithelial cells were similar in the reservoirs and the controls. In the reservoirs, the surface amplification factors due to villi and to microvilli (near the villus tips) were reduced by some 29% and 20%, respectively, indicating villus hypotrophy. It is concluded that only minor morphologic changes appear in the ileal reservoir mucosa 15 to 19 years after construction. Morphometry provides a sensitive tool to demonstrate such changes in intestinal morphology.     

Bacteria and the mucus blanket in experimental small bowel bacterial overgrowth.

Self-filling blind loops were created experimentally in jejunal segments of specific pathogen-free male Wistar rats, and the loop contents and mucosa were examined over an 8-week period for evaluation of the interaction between mucus and luminal bacteria. Corresponding jejunal segments from rats that did not undergo surgery were used as controls. Proliferation of anaerobic bacteria developed in the test animals by the first week after surgery. Despite anaerobic bacterial proliferation, no adherence by bacteria to the intestinal microvillus surface was observed by scanning or transmission electron microscopy. Rather, bacteria were present within the mucus layer overlying the intestinal mucosal surface. Immunoassay of goblet cell mucin demonstrated an increase in the proportion of mucin present in the intestinal lumen and a decrease in mucin levels in the jejunal mucosa. These results suggest that the interaction of bacteria with mucus is an important mechanism of protection of the mucosal surface in experimental small bowel bacterial overgrowth.     

Lectin-binding sites in neoplastic and non-neoplastic colonic mucosa of 1,2-dimethylhydrazine-treated rats

Qualitative changes of glycoconjugates in luminal surface and goblet cell mucin from colon mucosa of 1,2-dimethylhydrazine (DMH)-treated rats were studied. Eight fluoresceinated lectins were used: Dolichos biflorus (DBA), Glycine max (SBA), Triticum vulgare (WGA), Limax flavus (LFA), Arachis hypogaea (PNA), Griffonia simplicifolia-I (GS-I), Ulex europaeus-I (UEA-I) and Canavalia ensiformis (Con A). The lectin-binding patterns were studied in tumors arising in proximal and distal portions of the colon, in transitional mucosa (TM) and in mucosa distant from tumors. Lectin reactivity observed in mucosa of DMH-treated rats was compared with that obtained in colon mucosa of control rats. In tumors and non-neoplastic mucosa of DMH-treated rats the reactivity of DBA, SBA, WGA, LFA, GS-I and Con A were similar to that in the mucosa of control rats. In contrast, important changes were observed in the reactivity of UEA-I and PNA. Contrary to the staining in the control mucosa, UEA-I bound intensely to all carcinomas and PNA to 50% and 60% of carcinomas arising in proximal and distal colon, respectively. Moreover, in TM and mucosa distant from tumors, UEA-I and PNA also differed in their binding patterns to that obtained in the colonic mucosa of the control rats. UEA-I- and PNA-binding to luminal surface and UEA-I-binding to the mucin of distal colonic mucosa from DMH-treated rats was similar to that observed in rat fetal colon suggesting a reappearance of a fetal-type pattern. Contrarily, PNA-reactivity in goblet cell and carcinoma mucin is a unique feature of colonic carcinogenesis not present during fetal development.     

正常胃肠道上皮粘液性质及其显示方法

应用组织化学方法包括PAS,AB/PAS,HID/AB,OR/AB,PAPS,mPAS,PB/KOH/PAS,PAT/KOH/PAS,PATB/KOH/PAS观察正常胃肠道粘膜分泌粘液的成分.对各种组织化学方法进行了比较,并对国内尚无报告的新方法进行了介绍.在正常胃粘膜表面上皮及胃窦腺体以分泌中性粘液为主.小肠主要分泌氮乙酰化唾液酸粘液,大肠上皮分泌以硫酸粘液及氧乙酰化唾液酸粘液为主.     

Ultrastructure of goblet-cell metaplasia from Clara cell in the allergic asthmatic airway inflammation in a mouse model of asthma in vivo

Mucus overproduction from goblet cells, a characteristic feature of the allergic asthmatic inflammation induced by ovalbumin (OVA) in mice, was examined morphologically. In OVA-untreated (normal) mice, there were no goblet cells in intrapulmonary bronchus and bronchiole. However, goblet cells with or without hyperplasia in the mucosa of inflamed bronchus–bronchiole were recognized in the allergic asthmatic mice. The non-ciliated epithelium containing electron lucent granules (mucus) showed many similarities to Clara cells, which have characteristic secretory granules and many mitochondria, except for the less-developed smooth endoplasmic reticulum seen in normal mice. Ciliated Clara cells with or without mucus were rarely recognized. In addition, mucus was found in neither ciliated nor basal epithelium. The present study suggests that goblet-cell metaplasia in the bronchus and bronchiole of inflamed mucosa may be derived, at least in part, from Clara cells.     

Qualitative assessment and morphometry in the study of the ileal reservoir after restorative proctocolectomy

Little is known about the long-term effects on the reservoir mucosa in patients with ulcerative colitis and familial polyposis coli who undergo proctocolectomy with subsequent construction of ileal reservoir/pouch and ileoanal anastomosis. In these patients, questions regarding adaptation towards a more colon-like mucosa and/or development of (pre)malignant changes are of particular importance. With the aim of designing a method for reliable evaluation of the mucosa in the ileal pouch, biopsies from 10 patients were studied by semiquantitative assessment and morphometry. The findings were compared with those obtained from normal jejunum, ileum, and colon. The following parameters were found to be important: Villous surface density, quantity of goblet cells, number of mitoses, and the presence/absence of predominantly sulphated mucin+ goblet cells. The number of Paneth cells did not show significant changes. The villous surface density was determined by a cycloid test system applied to vertical sections. Semiquantitative assessment was a sufficiently precise method for the evaluation of the quantity of goblet cells. The counting of sulphated mucin+ goblet cells was not reproducible, instead a simple statement about the presence or absence of these cells was judged to be adequate. The number of mitoses and of Paneth cells were counted directly. During the first year of function the ileal pouch showed signs of adaptation towards a colon-like mucosa: Reduction of villous surface density, increased mitotic activity, and appearance of sulphated mucin+ goblet cells. The number of Paneth cells did not show significant changes. The amount of goblet cells was generally not increased, rather reduced in some patients.     

Mucins in Barrett's esophagus: a histochemical study

To define the mucin secretion of Barrett's esophagus, 132 biopsy specimens from 37 patients were studied with histochemical stains for mucins. Columnar mucous cells contained largely neutral mucins, but scattered cells in over 70% of the biopsies also produced sialomucins and sulfomucins. Goblet cells contained sialomucins, sulfomucins, or both. The distribution and relative proportions of mucins varied considerably among biopsies and among patients. Barrett's esophagus histochemically represents a heterogeneous, partially differentiated epithelium analogous to incomplete intestinal metaplasia of gastric mucosa.     

Characterization of monoclonal antihuman small bowel and colon specific mucin antibodies

Three human small bowel and colon mucosal specific monoclonal antibodies with distinct morphologic and electrophoretic characteristics were generated by fusion of immunized Balb/c spleen cells and murine plasmacytoma cells. Morphologic specificity by indirect immunofluorescence (IIF) revealed three antibody binding patterns corresponding to villus surface (TP-NG-43), goblet cell apical granules (TP-NG-2), and a combined surface/goblet cell apical granule antibody (TP-NG-20). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) produced three distinct electrophoretic migration patterns. These antibodies reacted with very high molecular weight determinants: TP-NG-2, one band greater than 400 kD; TP-NG-20, two bands corresponding to 370-400 kD; and TP-NG-43, two bands in the 350-400-kD range with smaller bands in the 50-94-kD range. Cross-reactivity with various other human organ systems was evaluated by indirect immunofluorescence and SDS-PAGE electrophoresis with Western blotting. By IIF, all three monoclonal antibodies reacted very strongly with components of gastric mucosa. Weak cross-reactivity was seen with colon, rectum and mucin-producing adenocarcinoma of the colon. No cross-reactivity was observed by IIF with other mucin-containing and non-mucin-containing tissues. However, cross-reactivity with gastric mucin was not detected by enzyme-linked immunosorbent assay (ELISA) and Western blotting. Antibody reactivity with mucin was confirmed by purifying various regional gastrointestinal mucins and by subsequent testing by ELISA. Monoclonal antibody affinity columns were prepared and evaluated. The utility of these methods will allow for further definition of important goblet cell mucin glycoprotein characteristics and isolation of mucin subpopulations.     

Characterization and heterogeneity of monoclonal antibodies directed to intestinal mucin derived from Crohn's disease small bowel

A panel of 12 monoclonal antibodies were produced by immunization of Balb/c mice with small bowel epithelial cells obtained from a patient with active well-documented Crohn's disease. The clones were derived by screening with immunofluorescence microscopy; those with staining patterns suggestive of mucin directed epitopes were chosen for study. Several distinct patterns of staining reactivity were noted, including reagents with homogeneous, luminal, heterogeneous and peripheral goblet cell activity. In addition, SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting analysis revealed reactivity to high molecular weight mucin. The reactive antigen was resistant to proteinase digestion. No endoneuraminidase activity was detected; however, one neuraminidase sensitive sialic acid epitope was demonstrated. Confirmation of glycoprotein epitopes was accomplished by testing purified mucins from several areas of the gastrointestinal tract by ELISA. Finally, individual small bowel goblet cell heterogeneity was demonstrated by immunofluorescence, Western blotting, and antibody affinity chromatography. These data demonstrate both by morphology and specific binding of antibody affinity chromatography a significant degree of small bowel goblet cell mucin heterogeneity.     

Expression of CDX2 and MUC2 in Barrett's mucosa

Barrett's mucosa is a risk factor for esophageal adenocarcinoma and should be detected at an early stage. It is defined by the presence of columnar epithelium with goblet cells in the lower esophagus, but histologic diagnosis can be uncertain in the absence of distinct goblet cells. We investigated 55 biopsies from 48 patients with endoscopically plain Barrett's esophagus and performed immunohistochemistry for CDX2 and MUC2. In addition, alcian blue (pH 2,5)/PAS staining was done. In histologically unequivocal Barrett's mucosa, nuclear expression of CDX2 in goblet cells and many columnar cells, as well as cytoplasmic positivity for MUC2 in goblet cells, could be observed. Alcian blue (pH 2,5)/PAS stained acidic mucins in goblet cells and in some non-goblet columnar cells. In six cases, no definite Barrett's mucosa was present, and no expression of MUC2 could be observed. In these biopsies, there was granular cytoplasmic and/or focal nuclear staining for CDX2 in non-goblet columnar epithelial cells, indicating their intestinal differentiation. We suggest that this peculiar mucosa is the precursor of unequivocal Barrett's mucosa and would designate it early Barrett's mucosa. Alcian blue for acidic mucins is inconsistent in this epithelium and does not reliably indicate early intestinal differentiation.     

Characterization of secretory cell glycoconjugates in the alimentary tract of the ruin lizard (Podarcis sicula campestris De Betta) by means of lectin histochemistry.

Secretory cell glycoconjugates of the alimentary canal of the ruin lizard (Podarcis sicula campestris De Betta) were characterized by traditional staining methods and by lectin histochemistry. The goblet cells of the upper esophagus produced sialo- and sulfomucins, while those of the lower esophagus mainly contained sulfomucins. Lectin histochemistry demonstrated the presence of N-acetyl-D-glucosamine and terminal sialic acid. The epithelial mucous cells lining the surface of the stomach and the gastric pits contained neutral glycoproteins with glycosidic residues of N-acetyl-D-galactosamine, D-glucose, D-mannose, D-galactose, and N-acetyl-D-glucosamine. The mucous cells of the gastric glands produced neutral glycoproteins that contained stable class-III mucosubstances, as revealed by Paradoxical Con A staining, with terminal residues of L-fucose and D-galactose. They can be similar to the true neck cells of the gastric pits of other vertebrates. The goblet cells of the small intestine produced acidic glycoproteins with glycosidic residues of N-acetyl-D-glucosamine, sulfated esters on internal residues and terminal sialic acid. In the large intestine, there is a predominance of sulfated mucosubstances with D-galactose, N-acetyl-D-glucosamine, and N-acetyl-D-galactosamine. The microheterogeneity of mucins of the digestive tract, as proved by lectin histochemistry, is probably connected to their different functions.     

Mucin isolated from rabbit colon inhibits in vitro binding of Escherichia coli RDEC-1.

The rabbit enteric pathogen Escherichia coli RDEC-1 (serotype O15:H-) mediates attaching and effacing binding to colonic epithelium in a manner morphologically identical to that observed in both human enteropathogenic E. coli and enterohemorrhagic E. coli infections. The aim of this study was to determine if colonic mucus and its constituents, including mucin derived from goblet cells, inhibited RDEC-1 adherence in vitro. Crude mucus was prepared from mucosal scrapings of rabbit colon and separated by buoyant density into eight fractions. Purified mucin was characterized by gel electrophoresis, dot immunoblotting, indirect immunofluorescence, and amino acid composition. RDEC-1 bacteria were grown to promote and suppress the expression of mannose-resistant, hydrophobic pili. A nonpiliated mutant, strain M34, was also used as a negative control. Binding of radiolabeled RDEC-1 expressing pili was quantitated in the presence of crude mucus, purified mucin, and nonmucin fractions. Binding of piliated RDEC-1 to hydrophobic polystyrene wells was greater than for both nonpiliated RDEC-1 and strain M34 (P less than 0.05). Both crude mucus and purified mucin mediated a concentration-dependent inhibition of piliated-RDEC-1 binding. Fractions of mucus without immunoreactive mucin did not inhibit the binding of RDEC-1 expressing hydrophobic pili. We conclude that colonic goblet cell-derived mucin mediates inhibition of piliated RDEC-1 attachment in vitro. Inhibition of bacterial adherence could prevent access of attaching and effacing E. coli enteric pathogens to the colonic mucosa in vivo.     

Mucin granule intraluminal organization

Mucus secretions have played a central role in the evolution of multicellular organisms, enabling adaptation to widely differing environments. In vertebrates, mucus covers and protects the epithelial cells in the respiratory, gastrointestinal, urogenital, visual, and auditory systems, amphibian's epidermis, and the gills in fishes. Deregulation of mucus production and/or composition has important consequences for human health. For example, mucus obstruction of small airways is observed in chronic airway diseases, including chronic obstructive pulmonary disease, asthma, and cystic fibrosis. The major protein component in the mucus is a family of large, disulfide-bonded glycoproteins known as gel-forming mucins. These proteins are accumulated in large, regulated secretory granules (the mucin granules) that occupy most of the apical cytoplasm of specialized cells known as mucous/goblet cells. Since mucin oligomers have contour dimensions larger than the mucin granule average diameter, the question arises how these highly hydrophilic macromolecules are organized within these organelles. I review here the intraluminal organization of the mucin granule in view of our knowledge on the structure, biosynthesis, and biophysical properties of gel-forming mucins, and novel imaging studies in living mucous/goblet cells. The emerging concept is that the mucin granule lumen comprises a partially condensed matrix meshwork embedded in a fluid phase where proteins slowly diffuse.     

Reciprocal control of colon-specific sulfomucin and sialosyl-Tn antigen expression in human colorectal neoplasia

 Histochemical reports claim that sulfomucins decrease and sialylated mucins increase during colon carcinogenesis. We examined the expression of colon-specific sulfomucins and sialosyl Tn antigen (STN) in normal small intestine, normal colorectal mucosa and colorectal tumours at different stages of progression immunohistochemically, using MAb 91.9H specific for colonic sulfomucins and MAb TKH-2 for STN. No expression of sulfomucins recognized by MAb 91.9H was found in normal small intestine, whereas STN staining was pronounced. The converse was the case in normal colorectal mucosa. Sulfomucins were still found in adenomas, but the amounts decreased with depth of invasion in cancers (P<0.001). In contrast, no STN could be detected in benign lesions, but staining became increasingly evident with invasion (P<0.001). This reciprocal control of expression of colon-specific sulfomucins and STN evident in tumour progression indicates that the mucous phenotype shifts from the colonic to the small intestinal type. Received: 10 September 1996 / Accepted: 4 February 1997