Changing pattern of cytokeratin 7 and 20 expression from normal epithelium to intestinal metaplasia of the gastric mucosa and gastroesophageal junction.

It is currently unclear whether intestinal metaplasia at the esophagogastric junction and in the distal esophagus represent a continuum of the same underlying disease process, i.e., gastroesophageal reflux, or constitute different entities with a different pathogenesis. Biopsies below the Z line might show specialized epithelium in some patients and the question is whether this is another form of short segment Barrett's esophagus or whether it is related to a generalized atrophic process of the stomach. Data from recent studies regarding the expression of cytokeratin CK7 and CK20 in intestinal metaplasia (IM) found at the gastroesophageal junction are conflicting. Prompted by these data we undertook the present study: a) to evaluate the expression of CK7 and CK20 in IM of the gastric cardia and to compare the findings with those in patients with Barrett's esophagus and IM of the gastric corpus and antrum mucosa; and b) to evaluate the immunophenotype of non-intestinalized cardiac mucosa and to compare it with that of normal gastric epithelium. We studied the expression of CK7 and CK20 on biopsy specimens from patients with long-segment Barrett's esophagus (n=17) and surgical resection and biopsy specimens of gastric cardia (n=15), corpus (n=14) and antrum (n=22) from patients with histological evidence of IM. Eighty-four biopsy specimens from 42 patients (antrum n=15, corpus n=20, cardia n=7) without evidence of IM were studied as a control group. We observed an immunophenotype characterised by diffuse moderate to strong CK7 staining on the surface and crypt epithelium combined with strong CK20 staining on the surface and superficial part of the crypts in 94.1% (16/17) of the cases with long-segment Barrett's esophagus, but in none of the 36 cases with IM in distal stomach (antrum and corpus). IM in the gastric cardia expressed the immunophenotype seen in IM of the gastric mucosa in 93.3% (14/15) of the cases. On the other hand, normal cardiac epithelium expressed patchy strong CK7 staining on the surface epithelium and on both, superficial and deep parts of the pits combined with patchy strong CK20 staining on the surface epithelium and superficial pits, a feature permitting distinction of the normal cardiac epithelium from those of the normal gastric antrum and corpus epithelium. We conclude that the expression of cytokeratins 7 and 20 can be used to distinguish the origin of IM of the gastroesophageal junction. The CK7/20 immunophenotype of IM in the gastric cardia closely resembles that of the IM in the gastric antrum and corpus and is different from IM in long-segment Barrett's esophagus. In contrast, the CK7/20 immunophenotype of the cardiac epithelium is different from that of the gastric antrum and corpus mucosa, suggesting that cardiac epithelium might not be a native normal gastric epithelium but one that is acquired as a consequence of longstanding inflammation. Changing pattern of CK7 and CK20 expression from normal to intestinalized epithelium suggests that IM arising from cardiac epithelium might have distinctive features.

Cytotoxic protein expression in non-Hodgkin's lymphomas and Hodgkin's disease.

Recent studies have shown that some peripheral T-cell lymphomas (PTCL) could be derived from lymphocytes with cytotoxic potential. Therefore, we have investigated by immunohistochemistry 34 cases of PTCL including 2 cases of hepatosplenic gamma delta PTCL and 5 cases of sinonasal NK-cell lymphomas as well as 7 cases of T-lymphoblastic lymphomas (T-LBL) for the expression of the cytotoxic proteins TIA-1 and granzyme B. In addition, 50 cases of Hodgkin's disease (HD) were investigated in order to see if these cytotoxic proteins are expressed by Hodgkin and Reed-Sternberg (HRS) cells. Expression of the TIA-1 is characteristic of cytotoxic cells regardless of their activation status whereas expression of granzymes is highly increased in activated cytotoxic cells. All the five cases of sinonasal NK-cell lymphomas expressed TIA-1 and granzyme B in most tumour cells. The two gamma delta PTCL cases expressed TIA-1 protein in most tumour cells but not granzyme B. Of the 32 other PTCL, 9 cases showed cytotoxic protein expression in tumour cells. These cases comprised 2 pleomorphic medium large cell (PML) (1 nodal and 1 intestinal) and 7 CD30 positive anaplastic large cell lymphomas (ALCL) (5 nodal and 2 cutaneous). Cytotoxic protein expression in our series appeared to be related to the location since 10/18 (55%) extranodal PTCL and NK-NHL and only 6/21 (28%) nodal PTCL expressed TIA-1, and related to histology since, in nodal PTCL, this pattern was observed in most anaplastic (5/6 cases) and in a few pleomorphic (1/9 cases) lymphomas, but not in AILD-type NHL (0/6 cases). The 7 cases of T-LBL did not express cytotoxic proteins in tumour cells. EBV was detected by EBER RNA in situ hybridization (RISH) in tumour cells in all 5 sinonasal NK-NHL and in scattered atypical cells in all 6 cases of AILD. Two of the 50 cases of HD weakly expressed TIA-1 and granzyme B in a proportion of HRS cells. EBV was detected by RISH in 19/50 cases of HD but no correlation was found between EBV status and expression of cytotoxic proteins in HRS cells. However, the finding that granzyme B positive cells were found very rarely in close vicinity of HRS cells suggests that the function of activated cytotoxic cells is locally inhibited by the HRS cells and/or the reactive cells in the vicinity of HRS cells. Taken together our data suggest that: a) sinonasal NK-cell NHL represent tumours of activated cytotoxic NK-cells, b) the hepatosplenic gamma delta PTCL represent tumours of nonactivated cytotoxic gamma delta T-cells, c) a small proportion of other PTCL, mostly anaplastic large cell lymphomas represent tumours of cytotoxic T-cells and d) only very few cases of HD expressing cytotoxic proteins in a proportion of tumour cells, could be derived from activated cytotoxic cells.

Expression of p53, p21, mdm2, Rb, bax and Ki67 proteins in lymphomas of the mucosa-associated lymphoid (MALT) tissue.

We have investigated by immunohistochemistry 38 cases of B-cell MALT-NHL comprising 23 high grade (HG) and 15 low grade-(LG) tumours for the expression of p53, mdm2, p21, Rb, Ki67, bcl2 and Bax proteins. P53, mdm2 and p21 proteins were found in at least 5% of the tumour cells in 13/23, 2/23 and 11/23 HG tumours, respectively. These proteins were detected in very rare tumour cells in LG tumours. The following patterns were recorded in HG tumours: p53+/p21+/mdm2+ (2 cases), p53+/p21+/mdm2- (7 cases), p53+/p21-/mdm2- (4 cases), p53-/p21-/mdm2- (18 cases) and p53-/p21+/mdm2-(2 cases). Proliferative Ki67 index and Rb protein expression were higher in HG than in LG MALT-NHL. Bcl2 protein was expressed in all LG MALT-NHL, whereas only 2/23 HG MALT-NHL were bcl2 positive in most tumour cells. Bax protein was expressed in all MALT-NHL with HG tumours being positive in higher proportion of tumour cells than LG tumours. These findings show that significant expression of p53, mdm2, p21,Ki67 and Rb proteins occurs more frequently in aggressive histotypes of MALT-NHL. The parallel Rb/Ki67 expression suggests that Rb protein expression in MALT-NHL is normally regulated in relation to the proliferative growth fraction of the tumours. The pattern p53+/p21+/mdm2 +/- may represent MALT-NHL with wild type (wt) p53 gene since mdm2 and p21 proteins are inducible by wt p53 gene. The pattern p53+/mdm2-/p21-may represent MALT-NHL with p53 gene mutations unable to activate expression of mdm2 and p21 proteins. MALT-NHL with the p53-/mdm2-/p21 + pattern may be consistent with p53-independent p21 expression. Bax protein expression in all MALT-NHL suggests a role for this protein in the pathogenesis of these tumours.

Expression of p53 and mdm-2 proteins in Hodgkin's Disease. Absence of correlation with the presence of Epstein-Barr virus.

The expression of p53 and mdm-2 proteins was analysed in parrafin sections from 39 cases of Hodgkin's disease (HD) and compared to the presence of Epstein-Barr Virus (EBV). P53 protein was found in Hodgkin and Reed-Sternberg (HRS) cells in 12/39 cases. Mdm-2 protein was found in HRS cells in 10/39 cases. EBV-encoded EBER1-2 mRNAs and LMP-1 protein expression were found in HRS cells in 16/39 cases. In view of the LMP-1 oncogenic potential in vitro, these findings suggest that EBV may be involved in the pathogenesis of a proportion of HD cases. The coexpression of mdm-2 and p53 proteins was found in HRS cells in 10 cases, whereas in 27 cases neither was identified and in 2 cases there was no coexpression of mdm-2/p53. The simultaneous p53/mdm-2 protein expression, in view of previous findings which showed that most cases of HD display no p53 gene mutations, suggests that mdm-2 protein expression may be one of the factors responsible for the stabilisation of p53 protein in these cases. This could be important, in the pathogenesis of these cases of HD, since mdm-2 may deregulate the p53 dependent growth suppressive pathway. Mdm-2-/ p53+ protein expression may reflect the stabilisation of p53 protein by proteins other than mdm-2, mutations in the p53 gene making it unable to activate mdm-2, or the deregulation of the mdm-2 gene. No relationship was found between the presence of EBV and the expression of p53 and/or mdm-2 proteins.