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Histol Hi stopathol (2001 ) 16: 1021 -1029 Histology and 001: 10.14670/HH-16.1021 Histopathology http://www.hh.um.es Cellular and Molecular Biology

Differential expression of laminin isoform (a2), (a3B1 and a6B4) and 20 in H. pylori gastritis

M.G.F. Salesl, L.E. Nasciuttil, D.E. Lorena1, M. Muzzi4 and L.C. Porto3,4 1 Departm ent of Histology and Embryology, UFRJ, Rio de Janeiro, 2School of Medicine Souza Marques, Rio de Janeiro, 3Department of Histology and Embryology, UERJ, Rio de Janeiro and 4Labs. Patol ogia Clinica e Investigacao Ltda, Rio de Janeiro, Brazil

Summary. The expression of laminin-l chain s (13J and speciali zed, sheet-like, ex tracellular matrix structures y1), laminin-2 (merosin ), integ rin recept ors to laminin th at separate the connective from epithelia, mu scl e (a3131 and a6(34) and cy tokeratin (CK20) were studi ed fib ers, blood vessels and nerves (Foid art et aI. , 1980; by immunohi stochemi ca l meth ods in gastric bi opsies Li ss itzky et aI. , 1986; Edds, 1997). In recent yea rs, the from antrum of 25 pati ents. H. pylori gastritis was fo und impo rt ance of e xtracellul ar matri x compone nt s, in 19 cases and int estinal metaplasia (1M) in four fr om especi all y th ose located at th e epitheli al-mesenchymal th ese 19. A noth e r 13 bi ops ies, all w ith 1M we re interface, has bee n illustrated in th e developing human immunostain ed to laminin-2. Laminin-I cha in s in small intes tin e (Haffen et aI. , 1989; Bea uli eu et aI. , norm al and gastritis areas without 1M were ex pressed as 1991). Laminins are th e major BM glycoprote in s a strong, linea r and continuous deposit in the basement throughout th e body, composed by 3 chains (al -5; 131 -3; membranes of the superfi cial and glandular epithelium . y1-2) assembled into heterotrimeric isoforms (Chung et In metapl as ti c glands the reacti vit y to laminin-l chains aI. , 1979; Timpl et aI. , 1979; Burgeson et aI. , J 994; was decreased. Merosin was di scontinuous when a Min er et aI. , 1997). Laminins ari se very ea rl y during th e mode rate to accentu ated H. pylori glandular coloni za ti on deve lopme nt , a nd pl ay an import a nt ro le in th e was present. Sa mpl es with 1M we re negative to Iaminin- interacti ons and in th e maintena nce of g la nd a nd 2. The a3f31 and a6f34 s were nega ti ve onl y in epitheli a adult state (Beauli eu and Vac hon, 1994; Simon­ 1M gastri c bi opsies. The CK20 immunoreacti vit y was Ass mann et a I. , 1994; Pe rr eault et aI. , 1995). In stro ng and homogeneous in th e s at th e tip and the particul ar, merosin , or laminin a2 chain , is restricted to upper porti on of foveo lae in normal areas and in gastritis developing th e pit-gland structure of the forming glands with 1M th e reacti vit y to CK 20 was heterogeneous. A during gastric deve lopm ent up 20 weeks of gestati on di ffe renti al ex pression of laminin isoform s is related to (Trembl ay and Menard , 1996), and in the normal adult infl amm ati on and subsequ ent 1M caused by H. pylori. state is co nfin ed to the gastric and intestin al glandular T he a lt e rati ons o f a313 1 and a613 4 pa rall el both basement membranes (Simo et aI. , 199 1; Virtanen et aI. , modifications in merosin and CK2 0 expression in H. 1995; Trembl ay and Menard , 1996). However, little is pylori chro ni c gastritis. kn ow about th e compositi on and di stri buti on of th e di fferent BM component s associated with th e developing gastric mucosa and mature gastric glands (Tremblay and Key words: Laminins chain s, Cy tokeratin , Helicobacter Menard , 1995, 1996). pylori gastritis, Integrins Integrin s are he te rodime ri c cell surface glycopro tein s th at medi ate divalent cati on-depend ent ce ll-cell and ce ll -matri x interactions (Buck and Horwitz, Introduction 1987; Hynes, 1987). They are composed of a single a subunit associated with a sin gle 13 subunit and thi s The processes of deve lopm ent, cell growth and cell associati on is required for cell sur fa ce expression. The differenti ati on are cl osely related with the interacti ons interacti ons medi ated by integrins arc responsible fo r between cell s and th e ex trace llular matrix , whi ch is cert ain typi ca l properti es of adhesive ce ll s, such as composed by int erstiti al component s and basement attachment and migrati on, but these molecules are also membrane (BM ) (E kbl o m e t a I. , 1986). BM s are recogni zed to contribute to intrace llular signaling processes (Hynes, 1992; Humphries, 1999). Amongst Offprint requests to: Prof. LUIS Cri stovao Porto, Depa rtm ent of Histology th e laminin binding integrins, the a3f31 integrin binds and Embryology, IBRAG, UERJ, Av. Prof. Manoel de Abreu, 444 30 in 2, 4 and 5 (Rousse lle and Aumaill ey, 1994) and andar, 20551·170 Rio de Janeiro, Brazi. Fax: 55 21 5876511. e-mail : ca nn ot pl aya major ro le in to laminin-I Icporto@uerj. br (Aum ailley et aI. , 1990). The integrin a6f34 has bee n 1022 Laminins and CK20 in H. pylori gastritis

studied by immunoelectron microscopy and its enanthematous areas in which the histopathology distribution has been described at the basal side of revealed only minimal gastritis; the samples collected several epithelial cell types, suggesting that this integrin from normal endoscopic adjacent areas exhibited normal plays a role in polarity and adhesion of epithelial cells to histology. From each sample area (n = 29), one fragment the BM (Marchisio et al., 1991). Several works was immediately frozen in liquid nitrogen and stored at demonstrated that a6J34 polarization is lost upon -70 °C, the other being embedded in paraffin. Diagnoses tumorigenic transformation of epithelial cells were confirmed from standard hematoxylin-eosin, (Rabinovitz and Mercurio, 1996). Alcian-Blue-PAS and Waysson method for H. pylori. is the most complex of intermediate Another 13 antral biopsies in which chronic gastritis filaments and belongs to a great family of related with intestinal metaplasia without dysplasia was that vary in molecular weight and are coded by histologically detected, were randomly selected from a complex set of genes, expressed in different types of paraffin-embedded samples of the Labs Patologia epithelium that contain distinct keratin profiles (Franke Clfnica e Investiga~ao Laboratorial pathology service. et aI., 1981). Cytokeratin 20 (CK20), was specifically Gastritis was evaluated based on the criteria of the detected as a component of intestinal and gastric Sydney score (Sipponen et aI., 1991). foveolar epithelium (Moll et aI., 1990, 1993) and remains unchanged even during intestinal metaplasia or Antibodies malignant progression (Moll et aI., 1993; Schwerer and Baczako, 1996). The monoclonal antibodies used in this study were H. pylori has been considered as a causal agent of against laminin chains: a2 (Mab1922 diluted 1:1000), chronic gastritis in humans and may be associated with /31 (Mabl928 diluted 1:500), yl (Mab1920 diluted gastric cancer (Valkonen et aI., 1994; SoIcia et aI., 1996). 1 :500), from Chemicon International Inc, against Several works have emphasized that the adhesion of H. integrin to laminins: a6B4 (Mab1982 diluted pylori to laminin disorganizes the gastric epithelium 1:100) from Chemicon International Inc. and a3B I altering the interactions between laminin and laminin (M0608 diluted 1:200) from Dako Corporation. All receptor in gastric epithelial cells (Slomiany et aI., 1991; antibodies were used for immunofluorescence staining Valkonen et aI., 1994; Sales et aI., 1998). The mucosal on frozen sections and merosin (a2 laminin chain) was BM has been considered to playa role in the high also applied in paraffin sections. For the cytoskeleton, capacity of mucosal repair after injury (Mikami et aI., the monoclonal antibody anti-cytokeratin 20 (CK 20) 1994), but the way gastric BM component expression from Dako Corporation was used on the paraffin occurs during injury, remains unknown. sections. We decided to detect, by immunohistochemical methods, the expression of 131, y1, and a2 laminin Immunohistochemistry chains, their integrin receptors a6J34 and a3J31 and cytokeratin 20 (CK20) in the gastric mucosa with H. The frozen tissue specimens from normal and pylori chronic gastritis. Aim: to investigate whether the chronic gastritis areas, were sectioned at 5 ,urn and fixed inflammatory and metaplastic process caused by H. in acetone precooled to -20 °C. After washing in pylori alters the expression of BM extracellular phosphate buffer saline/ serum bovine albumin molecules and CK20 intermediate filament. (PBS/BSA), pH 7.4, the frozen sections were incubated with the primary antibody (anti-a2, 131 , yl laminin Materials and methods chains, anti-a3/31 or a6/34 integrin) for one hour. The procedure was continued by incubating the sections with Gastric samples a fluorescein-isothiocyanate-conjugated goat anti-mouse, for 30 minutes, followed by three washes in PBS and Samples of antral gastric mucosa from 25 patients mounting in buffered glycerol. The specimens were with chronic gastritis were obtained by endoscopic examined in a Zeiss microscope with epi-illumination means at the University Hospital of UFRJ, Rio de and the appropriate filter. Janeiro. Patients ranged from 37 to 67 years old, being For the immunoperoxidase staining, the paraffin­ 18 male and 9 female. The principal symptoms reported embedded specimens were sectioned at 4 ,urn on were: abdominal pain, epigastric burning and distension, silanized slides to avoid damage to the sections during periodic nausea, flatulence and halitosis. The criteria of the procedure. A duet kit (Dako Corporation) was used selection were: a) H. pylori negative cases were included according to the protocols provided by the distributor. To based on no previous eradication therapy; b) patients detect CK20, the sections were dewaxed in xylene and with neoplasia, especially in the gastrointestinal tract, rehydrated with graded alcohol to distilled water. were excluded; c) all the patients had not a specific drug Antigen retrieval was carried out in conjunction with intake, especially non-steroid anti-inflammatory drugs, microwave oven heating. Following washing for 10 at least 2 weeks before the endoscopy; d) cases with minutes in PBS at pH 7.4, the endogenous peroxidase previous gastric surgery were also excluded. Control activity was blocked with 0.6% H20 2 in methanol for 15 fragments were obtained from four patients with focal minutes. The sections were then washed in PBS for 10

I' 1023 Laminins and CK20 in H. pylori gastritis

mi nutes and incubated with non-immune sheep serum at substrate solu tio n conta ining H20 2 a nd 3,3 ' 1 % to reduce the background . After this, the primary dia minobenzidine (DAB) in PBS, pH 7.4. The sections antibody was applied (anti-a2 laminin chain or anti-CK were then coun terstain ed with Mayer's hematoxylin 20), diluted with non-immune sheep-serum at 1 %, and (Merck) diluted with distilled water 1:2, washed in inc ubated fo r one hou r. For the eva lu ati on of water, de hyd rated in alcohol, clea red in xy lene and im munostaining, the prim ary antibody was replaced by moun ted with En tell an (Merck). non-immune serum to provide a negati ve contro l. This was fo ll owed by three washes in PBS and a second Results in cuba ti on with biotinylated goat anti-mouse antibody fo r 30 minu tes. Foll ow in g thi s, the sections were From the 25 samples of chroni c antral gastntls, 19 incubated with streptav idin-perox id ase complex fo r 30 (76%) were positive to H. pylori , hav ing qu antities that minutes . All the incub ati ons were carried out at room ra nged from minimal (36%) to moderate (36%) and temperature. The immunoreacti vity was detected by a accentuated (4%). In addition, fro m the total number of

Fig. 1. Immunofluorescence to laminin-1 chains of normal gastric mucosa areas and of H. pylori ch ron ic gastritis with intestinal metaplasia. A and B. FITC indirect immunofluorescence with anti-B1 chain antibody. C and D. FITC indirect immunofluorescence with anti -y 1 chain antibody. A. Superficial epithelium (*) from normal antrum area showing an intense, linear and continuous reaction to B1 chain (arrow-heads). of capillaries (thin arrows) in the stroma also exhibit intense staining. B. Chronic gastritis with intestinal metaplasia. Weak to moderate and irregular reaction to B1 chain in the basement membrane (arrow-heads) underneath the glandular portion with three goblet cells (*) . Basal lamina of a capillar (thin arrow) in the stroma exhibit intense staining. C. Superficial epithelium (*) basement membrane from normal antrum area showing an intense and continuous reaction to y1 chain (arrow-heads). D. Chronic gastritis with intestinal metaplasia. Irregular and discontinuous reaction to y1 chain in the basement membrane (arrow-heads) of a intestinalized gland portion. x 860 1024 Laminins and CK20 in H. pylori gastritis

samples, 4 showed intestinal metaplasia: 2 complete, accentuated, the reactivity was less intense and staining exhibiting all the cellular components of the intestin al di scontinuity of the BMs was seen both with anti-Wi mucosa, and 2 incomplete. (Fig. IB) a nd yl (Fig. ] D) a ntibo di es in these m e ta plastic cases . R eactivity to basal la mina of Expression of f31 and y1 laminin chains capillaries was intense with both antibodies.

Laminin 131 chain was observed o n the BM of Expression of a2 laminin chain (merosin) superficial (Fig. lA) and g landular epithelium, from normal areas, as a linear and continuous deposit. Those In th e no rmal a reas, the BMs of the g landula r areas, histologicall y diagnosed as gastritis, showed that, epithelium showed a linear and continuous deposit of a2 independently of whether or not H. pylori was detected, chain (Fig. 2A). However, in the gastritis areas, the and independently of gastritis activity and th e extent of expression of a2 chain was not uniform . The glandular inflammation, the BMs were also stain ed with a linear epithelium BMs showed staining patterns varying from and continuous deposit of 131 c hain (not shown). The linear continuous to discontinuous. In the samples with expression of la minin yl was s imila r to 131 c hain gastritis where no H. pylori was detected, the BMs s howing the sa m e p a tte rn of staining (Fig. IC). showed a linear and continuous deposit of a2 chain and However, in the four cases of gastritis with metapl asia, discontinuity was seen in those samples exhibiting whe re the infl a mmatio n ranged from moderate to moderate and accentuated presence of H. py lori and

Table 1. Immunoreactivity of pyloric glands to basement membrane laminin isoforms, to integrin receptors, and of superficial epithelium to cy10keratin 20 (CK20) in gastri C fragments of patients with chronic gastritis.

LAMININS LAMININ a2 INTEGRINS CK20 SUPERFICIAL 13 1 AND y1 a 3131 and a 6134 EPITHELIUM

Normal antrum and ch ronic gastritis Intense, continuous Intense, continuous Intense baso lateral Intense baso-apical without H. pylori and lin ear and linear deposit. Moderate cytoplasmatic filaments (no inflammatory activity) in chronic gastritis Chronic gastritis Y,\'ith moderate or Intense, continuous Intense, discontinuous a3131 - moderate to Intense basal accentuated H. pylori colonization and li near and li near intense basolateral deposit cytoplasmatic (moderate and accentuated a 6134 - irregular some filaments inflammatory activity) glands with basal others with lateral deposits Intestinal metaplasia areas of Weak to moderate, Non-reactive Non-reactive Goblet cells - H. pylori chronic gastritis continuous and linear non-reactive (moderate and accentuated Absorptive columnar inflammatory activity) cell - apical pole

Fig. 2. Immunostaining to laminin a2 chain of H. pylori chronic gastritis with or wi thout intestinal metaplasia. A. FITC indirect immunofluorescence on frozen section. Chronic gastritis without intestinal metaplasia. The glandular basement membranes show an intense, linear and continuous deposit. x 215. B. Immunoperoxidase method on paraffin embedded section. No reaction is seen in the ch ron ic gastritis with intestinal metaplasia. x 860 1025 Laminins and CK20 in H. pylori gastritis

inflammatory activity. No reaction was seen in the four cases of intestinalized glands, but in all the 25 samples, strong stromal reactivity was found. The sections of paraffin-embedded samples were also stained by peroxidase method with anti-merosin antibody. The results were similar to those with the immunofluorescence method (not shown). No reactivity of gastric BM areas with intestinal metaplasia to merosin was confirmed on a further 13 paraffin-e mbedded samples. The intestinalized glands from complete or incomplete forms were always negative to merosin. In contrast, the normal glands had a linear reaction to a2 (Fig.2B).

Expression of cytokeratin 20

Paraffin-embedded sections were stained to CK20, in order to ascertain whether any alteration would be see n in the cytoskeleton. Immunoreactivity was restricted to the superficial epithelium, upper foveolae A and to a variable numbe r of single CK20-positive epithelial cells in the upper zone of the normal pyloric g lands (Fig. 3A). In normal areas, the strong reactivity was basal, with a filamentous pattern with a predominantly baso-apical orientation. Near the lateral and basa l me mbranes, a re inforce me nt of immunoreactivity was observed (Fig. 3B). The same staining was seen in the cases with gastritis without metaplas ia. Intestinal metaplasia areas exhibited a different pattern of staining. The reactivity was irregul ar and heterogeneous, i. e., some cells showed an intense reaction while others were negative. Goblet cells did not react with the CK20 antibody and or absorptive columnar cell s, the reactivity was restricted to the apical cell pole and basal reinforcement was seen, as in the samples without metaplasia (Fig. 3C).

Expression of a3f31 and a6f34 integrins receptors to laminin

In order to investigate the presence of integ rin receptors to laminin in chronic gastritis, antibodies against a3/31 and a6/34 were utilized in cryosections stained by indirect immunofluorescence. The a3/31 integrin was detected in all the normal gastric samples as an intense basolateral deposit of the pyloric glands and also in endothelial and interstitial cells (Fig. 4A). In the sections with chronic gastritis and H . pylori colonization, the reaction ranged from negative in the metaplastic glands to a moderate to strong reactivity in non-intestinalized epithelium, independently of th e inflammatory activity. The absence of reactivity in intestinalized glands was not associated with the type of

Fig. 3. Immunoperoxidase to CK20 on paraffin embedded section. A. Pyloric glands showing few positive CK20 cells (arrows). B. Superficial epithelium of normal area with a regular distribution of CK20. C. Chronic gastritis with intestinal metaplasia exhibiting a irregular aspect of CK20 distribution. Globet cell did not react with CK20 antibody (*). x 860 1026 Laminins and CK20 in H. pylori gastritis

intestin al metaplasia. The expression of a613 4, although s imilar to that seen in a3131 staining, in some cases showed a lateral reaction and while in others, a basal localizati on (Fig. 4B). Areas w ith intestinal metaplasia di d not react with the a6134 antibody (Fig. 4C). The results were summari zed on Table 1.

Discussion

In this report, we a na lyzed the expressio n a nd di stribution of a2, [31 and y1 laminin chains, their a313 1 and a613 4 integrin receptors and the cytokeratin 20 of antral biops ies with gastritis w ith or without H. pylori cell s, a nd corre la te d th e ir d ist ri b uti o n w it h morphological changes during this di sease. The patterns of 131 and y1 expression in normal areas are similar to those report ed for the human fe tal and adult gastric mucosa (Virtanen et aI. , 1995; Tremblay a nd Menard, 1996). S ince the baseme nt me mbranes were also stain ed with a linear and continuous deposit of 13 1 and y1 laminin chains, gastritis w ith H. pylori and subsequent in flammati on not change the expression of th ese two laminin chains. However, the intestin ali zati on p rocess a nd the degree of infl a mm atio n s uggest a modi ficatio n of the expression of these two laminin chain s. In contrast, in areas from gastritis, the merosin reacti vity ranged from continuous to discontinuous, and the discontinuity was always H. pylori associated, thus indicating that a2 chain expression can be modulated by H. pylo ri co lo nizatio n a nd b y t he a m o unt of inflammatory cells present in the lamina propria. The results of this s tudy also s howed that w he n gastri c g la nds lose the ir typi cal appearance and acquire an intestinal pattern , the expression of merosin is removed from the BMs. Moreover, even in absence of merosin in the 8M intestinalized glands, the stroma stain ed to it. Then, in gastritis with complete or incomplete intestinal metapl asia, merosin expression may not be regulated by heterologous cell -cell interacti on as suggested by Sim on­ Assman et al. (1994). T he interacti ons w ith epi theli al and mesenc hyma-derived cell s, on producing merosin , m ay b e depe nde n t o n the m a intenance of the differentiated state of both cellular types (Parker et aI. , 1974; Neal and Potten, 1981; Kedinger, 1994). Merosin is not o nl y in volved with glandular development, but also with the maintenance of adult glandular structures of all gastro intestinal tract (Simo et aI. , 1991; Simon­ Assman et a I. , 1994; Perrault et aI. , 1995; Virtanen et aI. , 1995; Lohi et aI. , 1996; Tremblay and Menard , 1996).

Fig. 4. Immunofluorescence to integ rins receptors to laminin of normal gastric mucosa areas and of H pylori chronic gastritis with and without intestinal metaplasia. A. a 3B 1 integrin in glandular epithelium from normal area showing a strong basolateral reaction (arrows) . Endothelial and some interstitial cells in the stroma exhibit intense staining. B. a6B4 in ch ron ic gastritis. Moderate reaction is seen in the basolateral portion of the glandular epithelium (arrow-heads) . C. a6B4 in chronic gastritis with intestinal metaplasia. No staining in the glandular basement membrane is observed. x 860 1027 Laminins and CK20 in H. pylori gastritis

Although intestinal metaplasia develops after H. pylori (Moll et a I. , 1990). Schwerer and Baczako (1996) infection, it may also appear for other reasons. The fact reported an intense and uniform reactivity to CK20 in that a mucosal colonization by H. pylori may change the enterocytes and goblet cells in the same disease. We did merosin expression (discontinuity), suggests that the not find a positive reaction in goblet cells, probably by binding of J-/. pylori to surface epithelial cells and the density of intermediate filaments is low in central subsequent inflammatory response playa role in the portions of these cells, due to mucin accumulation, as modulation of this molecule during the process of reported by Specian and Neutra (1984). Moreover, the glandular renewal. pattern of expression of CK20 in association with CK7 Intestinal metaplasia is a different tissue to the non­ was recently used to distinguish Barret's esophagus from metaplast ic gastric glands and expresses different intestinal metaplasia (Ormsby et aI., 1999). In the antigens to non-metaplastic epithelium. Several works intestinal metaplasia, cells positive for CK20, alternating have suggested that the development of gastric with negative cells, probably differ functionally from adenocarcinoma is related to intes tinal metaplasia each other. (Lauren, 1991). Furthermore, intestinal-type dysplasias, Taken together, these findings suggest that a adenomas and also adenocarcinomas arise from thi s differential expression of laminin isoforms is related to region, suggesting that they share a common origin inflammation and subsequent intestinal metaplas ia (Hattori and Sugihara, 1996). It seems to us that in the caused by J-/. pylori. In conclusion, the alterations of absence of merosin during the intestinalization process, integrins (a3B1 and a6B4) parallel both modifications in the stem cell loses its pathways of differentiation and laminin isoform (a2) and CK20 expression in H. pylori this loss may leave the glandular cell in a determined chronic gastritis. tubule to a preneoplastic state. The integrins a6B4 and a3f31 have been related to an References anchorage process between the and the actin or keratin-based cytoskeleton (Carter et aI., Aumailley M., Timpl R. and Sonnenberg A. (1990) . Antibody to integrin 1991; Niessen et aI., 1997). The a6f34 integrin mediates a6 subunit specifically inhibits cell-binding to laminin fragment 8. stable anchorage of cells to laminins (Niessen et aI., Exp. Cell Res. 188, 55-60. 1997) while the a3B1 integrin plays a role in matrix Beaulieu J-F. and Vachon P.H. (1994). Reciprocal expression of laminin assembly (DiPersio et aI., 1997). In addition, studies A-chain isoforms along the crypt-villus axis in the human small relate the loss of polarization (Tennenbaum et aI., 1993) intestine. Gastroenterology 106, 829-839. or its absence (Downer et aI., 1993; Gui et aI., 1995) in Beaulieu J-F., Vachon P.H. and Chartrand S. (1991). Immuno­ the tumoral process. In this work a6B4 was detected at localization of extracellular matrix components during organogenesis basal localization and also at the lateral membranes in of the human small intestine. Anal. Embryo l. 183, 363-369. glands colonized by J-/. pylori. In intestinalized glands, Buck C. and Horwitz A.F. (1987). Cell surface receptors for extracellular no reaction to a6B4 and a3B1 integrins was observed, as matrix molecules. Annu. Rev. Cell BioI. 3, 179-205. in the merosin staining. Previously described as a Burgeson R.E., Chiquet M., Deutzmann R. , Ekblom P. , Engel J., laminin-1 receptor (Lee et aI., 1992) it has now been Kleiman H., Martin G.R. , Meneguzzi G .. Pau lsson M., Sanes J., confirmed that a6B4 is a receptor not only for laminin-l, Timpl R. , Tryggvason K., Yamada Y. and Yurchenco P.D. (1994), A but also for several laminin isoforms (Mercurio, 1995; new nomenclature for the laminins. Matrix BioI. 14, 209-211 . Spinard et aI., ] 995). No reactivity of either merosin or Carter W.G. , Ryan M.C. and Gahr P.J. (1991) . Epiligrin, a new cell a6B4 in the glands displaying intestinal metaplasia, adhesion ligand for integrin Cl3fl , in epithelial basement membranes. suggests that this integrin is also a merosin receptor. The Cell 65, 599-610. results of this work are partially different that those Chung A.E., Jaffe R., Freeman I.L., Vergnes J.P., Braginski J.E. and found by Tani et al. (1996), in which a6B4 was detected Carlin B. (1979). Properties of a basement membrane-related in glands with intestinal metaplasia, although like this synthesized in culture by a mouse embryonal study, no merosin was observed in intestinalized glands carcinoma-derived cell line. Cell 16, 277-287. neither in the complete or incomplete forms. DiPersio C.M. , Hodivala-Dilke K.M., Jaenisch R. , Kreidberg J.A. and The results of CK20 showed that in normal areas Hynes R.O. (1997). 03fl, integrin is required for normal development and in gastritis without metaplasia the immunoreactivity of the epidermal basement membrane. J. Cell BioI. 137, 729-742. was strong and homogeneous in the cells at the tip and Downer C.S. , Watt F.M. and Speight P.M. (1993). Loss of CIS and fl4 the upper portion of the foveolae. In the lamina propria, integrin subunits coincides with the loss of basement membrane pyloric glands, few cells positive to CK20 were components in oral squamous cell carcinomas. J. Pathol. 171 , 183- exhibited that were probably endocrine cells, as reported 190. by Moll et al. (1993). However, in gastritis with Edds L.L. (1997) . Laminin and the mechanism of neuronal outgrowth. intestinal metaplasia, the reactivity to CK 20 was not Brai n Res. Rev. 23,1-27. homoge n eous, showing some cells with intense Ekblom p " Vestweber D. and Kem ler R. (1986). Cell matrix interactions immunolabeling while others were negative. This and cell adhesion during development. Annu. Rev. Cell BioI. 2, 27- difference can be explained by the mosaic-like patterns 47. of positive and negative cells, which is a feature of the Foidart J-M. , Bere E.w., Yaar Jr M., Rennard S.I., Gullino M., Martin distribution of CK20 in normal and transformed tissues G.R. and Katz S, 1. (1980) . Distribution and immunoelectron 1028 Laminins and CK20 in H. pylori gastritis

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