Use of immunohistologic and in situ hybridization techniques in the examination of sacroiliac joint biopsy specimens from patients with ankylosing spondylitis

OBJECTIVE

To investigate mechanisms involved in inflammation and new bone formation in the sacroiliac (SI) joints of patients with ankylosing spondylitis (AS).

PATIENTS AND METHODS

Computed tomography-assisted biopsy of the SI joint was performed in 5 patients with AS with a mean disease duration of 4.5 years and radiographic stage 2-3 disease. Immunohistologic studies were performed with the alkaline phosphatase-anti-alkaline phosphatase technique, and cytokine messenger RNA (mRNA) was detected by in situ hybridization.

RESULTS

Dense cellular infiltrates with varying amounts of CD3+ cells (mean +/- SD 53.3 +/- 24.1%), CD4+ cells (29.7 +/- 17.6%), CD8+ cells (15.8 +/- 11.4%), CD14+ cells (23.6 +/- 16.9%), CD45RO+ cells (48.4 +/- 23.6%), and CD45RA+ cells (4.5 +/- 2.9%) were found in the synovial portion of the SI joints of all 5 patients. In these infiltrates a high amount of tumor necrosis factor alpha (TNF alpha) mRNA and, near the site of new bone formation, a lower amount of transforming growth factor beta (TGF beta) mRNA, were detected, while no message for interleukin-1 was found in the 3 patients examined by this technique.

CONCLUSION

The presence of T cells and macrophages was demonstrated in cellular infiltrates in the SI joints of 5 patients with active AS. The finding of abundant TNF alpha message in these joints could have implications regarding potential immunotherapeutic approaches to this disease. TGF beta might be involved in new bone formation in AS.

Epstein-Barr virus latent membrane protein expression in Hodgkin and Reed-Sternberg cells

Cryostat sections from lymph nodes of 47 Hodgkin disease patients were examined by immunohistology for the Epstein-Barr virus (EBV)-encoded latent membrane protein (LMP), nuclear antigen 2, and late viral glycoprotein gp350/250. A distinct LMP-specific membrane and cytoplasmic staining was detected exclusively in Hodgkin and Reed-Sternberg cells in 18 patients (38%); EBV nuclear antigen 2 and gp350/250 immunoreactivity was absent in all instances. Thirty-two of 47 (68%) cases contained EBV-specific DNA sequences as detected by PCR, all LMP-positive cases being in this category. Our results confirm previous studies establishing the presence of EBV genomes in Hodgkin and Reed-Sternberg cells by demonstrating expression of an EBV-encoded protein in the tumor-cell population. The finding of LMP expression in the absence of EBV nuclear antigen 2 suggests a pattern of EBV gene expression different from that of B-lymphoblastoid cell lines and Burkitt lymphoma, whereas this finding shows similarities with that seen in undifferentiated nasopharyngeal carcinoma. Because the LMP gene has transforming potential, our findings support the concept of a pathoetiological role of EBV in many cases of Hodgkin disease.

In situ hybridization for procollagen types I, III and IV mRNA in normal and fibrotic rat liver: evidence for predominant expression in nonparenchymal liver cells

The expression of alpha 2(I), alpha 1(III) and alpha 1(IV) procollagen mRNA was analyzed in normal and CCl4-induced fibrotic rat liver by in situ hybridization using RNA probes. In normal liver, moderate amounts of alpha 2(I) and alpha 1(III) procollagen transcripts were found in sinusoidal cells, in stromal cells of the portal tracts and in the vicinity of central veins, whereas a1(IV) procollagen gene expression was below the threshold of detection. After 2 weeks of CCl4 treatment, increased transcription of alpha 2(I) and alpha 1(III) procollagen genes was observed in sinusoidal cells. At this stage, alpha 1(IV) procollagen mRNA was detectable in the same cell types and localization as alpha 2(I) and alpha 1(III) procollagen transcripts, although with a weaker signal. After 4 weeks, newly formed fibrous septa showed many cells intensely labeled by alpha 2(I), alpha 1(III) and alpha 1(IV) procollagen probes. Neither in normal liver nor at any stage of fibrosis was any hybridization signal above background observed in hepatocytes. These patterns suggest that in the liver Type I, Type III and Type IV procollagen expression takes place predominantly in nonparenchymal cells. Therefore, hepatocytes do not appear to be significantly involved in procollagen production in this experimental model of liver fibrosis.

Silymarin retards collagen accumulation in early and advanced biliary fibrosis secondary to complete bile duct obliteration in rats

Silymarin (SIL), a standardized plant extract containing about 60% polyphenole silibinin, is used as a hepatoprotective agent. Its antifibrotic potential in chronic liver diseases has not been explored. Therefore, we applied SIL to adult Wistar rats that were subjected to complete bile duct occlusion (BDO) by injection of sodium amidotrizoate (Ethibloc). This treatment induces progressive portal fibrosis without significant inflammation. Rats with sham-operation that received SIL at 50 mg/kg/d (n = 10) and rats with BDO alone (n = 20) served as controls, whereas groups of 20 animals were fed SIL at a dose of 25 and 50 mg/kg/d during weeks 1 through 6 or doses of 50 mg/kg/d during weeks 4 through 6 of BDO. Animals were sacrificed after 6 weeks for determination of blood chemistries, total and relative liver collagen (as hydroxyproline [HYP]), and the serum aminoterminal propeptide of procollagen type III (PIIINP). BDO in untreated rats caused an almost ninefold increase in total liver collagen (16.1 +/- 3.1 vs. 1.8 +/- 0.4 mg HYP, P < .001). SIL at 50 mg/kg/d reduced total HYP by 30% to 35%, either when given from week 1 through 6 or from week 4 through 6 after BDO (10.6 +/- 2.7 and 10.2 +/- 3.9 mg HYP, both P < .01 vs. BDO alone), whereas 25 mg/kg/d were ineffective. Because SIL at 50 mg/kg/d also reduced the collagen content per gram of liver tissue, it acted as a true antifibrotic agent. The single value of PIIINP at killing paralleled the antifibrotic activity of SIL with 11.6 +/- 3.8 and 9.9 +/- 3.7 vs. 15.3 +/- 5.2 microg/L in both high-dose groups (P < .05 and P < .01, respectively, vs. rats with BDO alone). Except for a decreased alkaline phosphatase and a lower histological fibrosis score in the groups that received SIL, clinical-chemical parameters were not different among all groups with BDO. We therefore conclude that 1) BDO with Ethibloc is a suitable model to test for pure antifibrotic drugs because it induces progressive rat secondary biliary fibrosis without major inflammation; 2) oral SIL can ameliorate hepatic collagen accumulation even in advanced (biliary) fibrosis; and 3) PIIINP appears to be a suitable serum marker to monitor the inhibition of hepatic fibrogenesis in this model of biliary fibrosis.

Powerful strategy for polymerase chain reaction-based clonality assessment in T-cell malignancies Report of the BIOMED-2 Concerted Action BHM4 CT98-3936

Polymerase chain reaction (PCR) assessment of clonal T-cell receptor (TCR) and immunoglobulin (Ig) gene rearrangements is an important diagnostic tool in mature T-cell neoplasms. However, lack of standardized primers and PCR protocols has hampered comparability of data in previous clonality studies. To obtain reference values for Ig/TCR rearrangement patterns, 19 European laboratories investigated 188 T-cell malignancies belonging to five World Health Organization-defined entities. The TCR/Ig spectrum of each sample was analyzed in duplicate in two different laboratories using the standardized BIOMED-2 PCR multiplex tubes accompanied by international pathology panel review. TCR clonality was detected in 99% (143/145) of all definite cases of T-cell prolymphocytic leukemia, T-cell large granular lymphocytic leukemia, peripheral T-cell lymphoma (unspecified) and angioimmunoblastic T-cell lymphoma (AILT), whereas nine of 43 anaplastic large cell lymphomas did not show clonal TCR rearrangements. Combined use of TCRB and TCRG genes revealed two or more clonal signals in 95% of all TCR clonal cases. Ig clonality was mostly restricted to AILT. Our study indicates that the BIOMED-2 multiplex PCR tubes provide a powerful strategy for clonality assessment in T-cell malignancies assisting the firm diagnosis of T-cell neoplasms. The detected TCR gene rearrangements can also be used as PCR targets for monitoring of minimal residual disease.

Phosphatidylinositol 3-kinase is required for platelet-derived growth factor's actions on hepatic stellate cells

BACKGROUND & AIMS

Platelet-derived growth factor (PDGF) is the most potent mitogen for hepatic stellate cells (HSCs) in vitro. The aim of this study was to investigate the role of phosphatidylinositol 3-kinase (PI 3-K) activation in mediating the biological effects of PDGF on cultured HSCs and its involvement in vivo.

METHODS

HSCs were isolated from normal human livers. PI 3-K was assayed on phosphotyrosine or PDGF-receptor immunoprecipitates by in vitro kinase assay.

RESULTS

Incubation of HSCs with PDGF caused a time-dependent increase in PI 3-K activity. Immunoprecipitation of PDGF-alpha and -beta receptors showed that both subunits associate with active PI 3-K in PDGF-stimulated HSCs. Wortmannin, a specific PI 3-K inhibitor, dose-dependently blocked PI 3-K activity induced by PDGF and inhibited DNA synthesis. PDGF (homodimer)-BB also stimulated HSC chemotaxis, which was inhibited by pretreatment with wortmannin. To explore the potential role of PI 3-K in vivo, liver homogenates from rats treated with CCl4 and from control rats were immunoprecipitated with anti-PDGF-beta-receptor antibodies. Liver injury was associated with increased PDGF-beta-receptor autophosphorylation, and greater PI 3-K activity associated with the receptor itself.

CONCLUSIONS

This study shows that in cultured HSCs, PI 3-K activation is necessary for both mitogenesis and chemotaxis induced by PDGF and that this pathway is up-regulated during liver injury in vivo.

Epstein-Barr virus-infected T lymphocytes in Epstein-Barr virus-associated hemophagocytic syndrome

The clonal composition of EBV-infected cells was examined in three cases of EBV-associated hemophagocytic syndrome by analysis of the heterogeneity of terminal repetitive sequences in the EBV genome, indicating monoclonal expansion of EBV-infected cells in all cases. Involvement of T lymphoid cells was determined by in situ hybridization using 35S-labeled RNA probes specific for the small EBV-encoded nuclear RNAs, EBER1 and EBER2, in combination with immunostaining for the TCR-beta chain, CD45RO, CD20, CD30 and CD68 antigens in these three cases. The majority of lymphoid cells showing EBER transcripts were stained by antibodies against CD45RO and T cell receptor-beta. In contrast, EBER-specific signals were not detectable on B cells or hemophagocytic cells. These data support the concept that EBV-associated T cell proliferation is a primary feature of EBV-AHS.

Procollagen expression by nonparenchymal rat liver cells in experimental biliary fibrosis

To localize the cellular sources of the collagens excessively deposited in the liver in the course of secondary biliary fibrosis, we have analyzed by in situ hybridization the distribution of alpha 2(I), alpha 1(III), and alpha 1(IV) procollagen and albumin RNA transcripts in rat livers up to 6 wk following common bile duct ligation and scission. In normal liver, moderate amounts of alpha 2(I) and alpha 1(III) procollagen RNA were found in nonparenchymal cells, while alpha 1(IV) procollagen gene expression was at the threshold of detection. Following bile duct obstruction, increasing amounts of alpha 2(I), alpha 1(III), and alpha 1(IV) procollagen gene transcripts were observed in cells of the expanding portal tracts and in perisinusoidal cells in areas of excessive collagen deposition. Procollagen gene expressing perisinusoidal cells were colocalized with desmin-immunoreactive cells, suggesting that Ito cells and transitional cells were among the collagen-expressing cell types. Only alpha 1(IV) procollagen transcripts were found in epithelial cells of newly formed bile ducts. Neither normal nor fibrotic liver showed any hybridization signal above background over hepatocytes, indicating that hepatocytes are unlikely to be a major source of hepatic collagen.

Epstein-Barr virus (EBV) infection in infectious mononucleosis: virus latency, replication and phenotype of EBV-infected cells

Primary Epstein-Barr virus (EBV) infection may manifest itself as a benign lymphoproliferative disorder, infections mononucleosis (IM). EBV infection has been characterized in lymphoreticular tissues from nine patients with IM using the abundantly expressed EBV-encoded nuclear RNAs (EBERs) as a marker of latent infection. Expression of the virus-encoded nuclear antigen (EBNA) 2 and of the latent membrane protein (LMP) 1 was seen in variable proportions of cells in all cases. Double labelling revealed heterogeneous expression patterns of these proteins. Thus, in addition to cells revealing phenotypes consistent with latencies I (EBNA2-/LMP1-) and III (EBNA2+/LMP1+), cells displaying a latency II pattern (EBNA2-/LMP1+) were observed. Cells expressing EBNA2 but not LMP1 were also detected; whilst this may represent a transitory phenomenon, the exact significance of this observation is at present uncertain. EBER-specific in situ hybridization in conjunction with immunohistochemistry revealed expression of the EBERs mainly in B-lymphocytes, many of which showed features of plasma cell differentiation. By contrast, convincing evidence of latent EBV infection was not found in T-cells, epithelial or endothelial cells. Double-labelling immunohistochemistry revealed expression of the replication-associated BZLF1 protein in small lymphoid cells, often showing plasmacytoid differentiation. There was no unambiguous expression of this protein in other cell types. These results suggest that B-cells are the primary target of EBV infection and that plasma cells may be a source of infectious virus found in the saliva of IM patients.

Immunoglobulin and T-cell receptor gene rearrangements in Hodgkin's disease and Ki-1-positive anaplastic large cell lymphoma: dissociation between phenotype and genotype

We have determined the tumor cell immunophenotype and the rearrangement configuration of immunoglobulin and T-cell receptor genes in 39 cases of Hodgkin's disease (HD), six HD-derived cell lines and 22 cases of Ki-1-positive anaplastic large cell lymphomas (Ki-1-ALC). Rearrangements were observed in 11/39 HD cases, 15/22 Ki-1-ALC, and all cell lines. Epstein-Barr virus DNA was found in five HD cases, one cell line, and one Ki-1-ALC. Both HD and Ki-1-ALC frequently displayed a dissociated genotypic and phenotypic maturation status, i.e. an immature genotype in association with late activation markers. We postulate that the tumor cells in many cases of HD and some cases of Ki-1-ALC may be derived from immature lymphoid cells by a transformation process that superimposes characteristics of mature activated lymphocytes on these cells.

Epstein-Barr virus and carcinomas: undifferentiated carcinomas but not squamous cell carcinomas of the nasopharynx are regularly associated with the virus

The Epstein-Barr virus (EBV) is consistently associated with undifferentiated nasopharyngeal carcinoma (NPC). There is, however, conflicting evidence as to whether squamous cell NPCs are also EBV-associated. Moreover, it has been proposed that other epithelial tumours, particularly thymomas and thymic carcinomas, should be included in the group of EBV-associated neoplasias. However, since the viral DNA in these studies was demonstrated only in extracted DNA, the cellular origin of the viral DNA is uncertain. We have therefore investigated 152 epithelial tumours from various sites for the presence of EBV-DNA by in situ hybridization with 35S-labelled probes. Sixty-eight of 77 undifferentiated NPCs showed an EBV-specific autoradiographic signal, thus confirming the strong association of this tumour type with EBV even in geographical areas where undifferentiated NPC is not endemic. None of eight squamous cell NPCs showed an EBV-specific signal. All of 15 carcinomas with a similar morphology to undifferentiated NPC but from different anatomic sites (thymus, tonsil, breast) were EBV-negative as were 9 thymomas, 26 squamous cell carcinomas of the palatine tonsil, and 14 cervical carcinomas. Our results therefore suggest a unique association of EBV with undifferentiated NPC and support concepts assigning different biological properties to undifferentiated NPC as compared with squamous cell NPC.

Proliferating bile duct epithelial cells are a major source of connective tissue growth factor in rat biliary fibrosis

Connective tissue growth factor (CTGF) is a downstream mediator of transforming growth factor-beta1 (TGF-beta1) and thus a potential target for antifibrotic treatment strategies. CTGF is up-regulated in disorders such as atherosclerosis, scleroderma, and fibrosis of kidneys and lungs. We investigated the temporospatial expression patterns of CTGF and TGF-beta1 mRNA in rat livers with acute fibrogenesis (after a single dose of CCl(4)) and with advanced fibrosis (6 weeks after complete bile duct occlusion). Multiprobe ribonuclease protection assay revealed increasing TGF-beta1 and CTGF mRNA levels 6 hours after injection of CCl(4), with peak levels after 72 hours. In biliary fibrosis TGF-beta1 and CTGF mRNA levels increased fourfold and sevenfold, respectively (P: < 0.001). In situ hybridization combined with cell-specific markers revealed CTGF transcripts in desmin-positive cells after a single dose of carbon tetrachloride, whereas no transcripts were found in normal livers. In biliary fibrosis, however, proliferating bile duct epithelial cells were the predominant source of CTGF mRNA. We conclude that in rat liver fibrogenesis CTGF is up-regulated in close association with TGF-beta1 and that, contrary to a previous report, not solely hepatic stellate cells but activated bile duct epithelial cells are the main source of this profibrogenic factor.

An oral endothelin-A receptor antagonist blocks collagen synthesis and deposition in advanced rat liver fibrosis

BACKGROUND & AIMS

Endothelin 1 induces contraction, proliferation, and collagen synthesis of hepatic stellate cells in vitro, which may be mediated via the endothelin A receptor. It is unknown if specific blockade of the endothelin A receptor inhibits hepatic fibrosis in vivo.

METHODS

Groups of 10-20 rats with bile duct occlusion were treated with the nonpeptide endothelin-A receptor antagonist LU 135252 at 80 mg. kg(-1). day(-1) from week 1-6 or from week 4-6, or with LU at 10 mg. kg(-1). day(-1) from week 1-6. Animals with bile duct occlusion alone and sham-operated rats without or with LU at 80 mg. kg(-1). day(-1) over 6 weeks served as controls. After 6 weeks, parameters of fibrogenesis were determined.

RESULTS

LU treatment led to improved histology, paralleled by a dose-dependence up to 60% reduction of liver collagen, even when administered at an advanced fibrosis stage. This was accompanied by a decreased messenger RNA of hepatic procollagen alpha1(I) and tissue inhibitor of metalloproteinase 1, 2 major effectors of fibrosis, and of serum procollagen type III, a surrogate marker of liver fibrogenesis.

CONCLUSIONS

Selective endothelin-A receptor blockade can dramatically reduce collagen accumulation in rat secondary biliary fibrosis, a model refractory to most potential antifibrotic agents. Endothelin-A receptor antagonists are promising antifibrotic agents in chronic liver disease.

Expression of platelet-derived growth factor in newly formed cholangiocytes during experimental biliary fibrosis in rats

BACKGROUND/AIMS

Chronic cholestasis stimulates a fibroductular reaction which may progress to secondary biliary fibrosis and cirrhosis. Since platelet-derived growth factor has been indicated as a major fibrogenic factor in chronic liver disease, we analyzed its expression and that of its receptor beta subunit in a rat model of chronic cholestasis.

METHODS

Liver tissue samples collected at 7, 10, 21, and 28 days after induction of cholestasis obtained by bile duct ligation, were analyzed by immunohistochemistry, in situ hybridization and RNase protection assay for the expression of platelet-derived growth factor (PDGF)-B chain and receptor beta subunit. Furthermore, the expression of PDGF-B chain mRNA was analyzed in highly purified cholangiocytes from normal and cholestatic rat liver.

RESULTS

In cholestatic liver, platelet-derived growth factor-BB and B chain mRNA expression increased up to 4 weeks in epithelial cells of proliferating bile ducts, and periductular mesenchymal cells. The increased expression of PDGF-B chain mRNA was confirmed in highly purified cholangiocytes obtained from normal and cholestatic rat liver. The expression of the receptor beta subunit progressively increased after induction of cholestasis and was mainly localized to desmin-positive periductular hepatic stellate cells.

CONCLUSIONS

These data suggest that platelet-derived growth factor-B chain can be synthesized by cholangiocytes during chronic cholestasis. The presence of its receptor on periductular hepatic stellate cells raises the possibility that, in this experimental setting, this cytokine might contribute to fibrogenesis in vivo.

Human endogenous retrovirus protein cORF supports cell transformation and associates with the promyelocytic leukemia zinc finger protein

Human endogenous retrovirus sequences (HERVs) reside in the genomes of primates and humans for several million years. The majority of HERVs is non-coding but a limited set is intact and can express proteins. We have recently identified an almost intact HERV-K(HML-2) provirus on chromosome 7 and have documented that most patients with germ cell tumors (GCTs) display antibodies directed against proteins of HERV-K(HML-2). To address whether these proteins merely represent tumor markers or contribute to neoplastic transformation, we examined the transforming potential of various HERV sequences and studied physical interactions between HERV and cellular proteins by yeast two-hybrid and biochemical assays. cORF, a protein encoded by the C-terminal open reading frame within the env gene, supports tumor growth in nude mice and associates with the promyelocytic leukemia zinc finger protein (PLZF). The interaction domains map between amino acid residues 21 and 87 of cORF, and between residues 245 and 543 of PLZF. PLZF is critical for spermatogenesis in mice. Abnormal spermatogenesis or maturation of gonocytes is thought to predispose humans to the development of germ cell tumors. Thus, cORF of human endogenous retroviruses may contribute to tumor development by interfering with processes during spermatogenesis that involve PLZF.

Demystified...tissue microarray technology

Several "high throughput methods" have been introduced into research and routine laboratories during the past decade. Providing a new approach to the analysis of genomic alterations and RNA or protein expression patterns, these new techniques generate a plethora of new data in a relatively short time, and promise to deliver clues to the diagnosis and treatment of human cancer. Along with these revolutionary developments, new tools for the interpretation of these large sets of data became necessary and are now widely available. Tissue microarray (TMA) technology is one of these new tools. It is based on the idea of applying miniaturisation and a high throughput approach to the analysis of intact tissues. The potential and the scientific value of TMAs in modern research have been demonstrated in a logarithmically increasing number of studies. The spectrum for additional applications is widening rapidly, and comprises quality control in histotechnology, longterm tissue banking, and the continuing education of pathologists. This review covers the basic technical aspects of TMA production and discusses the current and potential future applications of TMA technology.

Ductal epithelial proliferations of the breast: a biological continuum? Comparative genomic hybridization and high-molecular-weight cytokeratin expression patterns

According to current concepts, benign proliferative breast disease (BPBD) is a direct precursor of breast cancer, in a spectrum ranging from ductal hyperplasia to overtly invasive carcinoma. In this study, comparative genomic hybridization (CGH) was used to screen ductal hyperplasia and other BPBD lesions and ductal carcinoma in situ (DCIS) for common genomic abnormalities, to test the relationship between these hyperplastic and neoplastic lesions. Immunohistochemistry for cytokeratin 5/6 was used as a diagnostic adjunct to distinguish ductal hyperplasia from DCIS. A total of 42 cases of BPBD comprising ductal hyperplasia of the usual type (n=14), papilloma (n=22), tubular adenoma (n=3), and adenosis (n=3), as well as 52 cases of DCIS, were studied. All cases of BPBD consistently displayed the presence of a subpopulation of cytokeratin 5/6-expressing basal-type cells within the proliferative lesion, whereas all of the non-high-grade and most of the high-grade DCIS lesions lacked cytokeratin 5/6-positive cells. Whereas gross genomic alterations, as determined by CGH, were undetectable in BPBD, distinct genetic changes characterized all cases of DCIS, with one exception. These results confirm the usefulness of cytokeratin 5/6 immunohistology in the diagnosis of BPBD and neoplastic breast lesions and support the view that BPBD and DCIS are not closely related entities and that BPBD is not an obligate direct precursor of DCIS.

Long-term differentiated function of heterotopically transplanted hepatocytes on three-dimensional polymer matrices

Hepatocyte transplantation using porous matrices is under investigation as an alternative therapy for certain liver diseases. For this purpose, long-term function of transplanted hepatocytes is mandatory. This problem has not been sufficiently investigated yet. In this study Lewis rats were used as donors and recipients. Stimulated (group A, portocaval shunt) or unstimulated (group B) hepatocytes were transplanted into prevascularized polyvinyl-alcohol matrices. Cell-free matrices served as controls (group C). Matrices were harvested between 1 h and 1 year after implantation and analyzed by morphometry; albumin RNA in situ hybridization; and cytokeratin-, actin-, desmin-, and macrophage-specific antigen immunohistology. The hepatocyte number significantly decreased within the first week following implantation. Between 1 month and 1 year after transplantation a significant increase in hepatocyte number was noted in groups A and B. Albumin transcripts of transplanted hepatocytes were at normal levels at all times except for group B after 1 year. The immunohistology suggested engraftment of nonparenchymal liver cells. We conclude that 3-dimensional matrices provide a sufficient environment for long-term engraftment of transplanted liver cells. The hepatocytes are able, despite suboptimal initial engraftment, to repopulate the scaffold for at least half of the recipient's life span and maintain cell-specific function after sufficient stimulation.

Matrix-metalloproteinases 1, 2, and 3 and their tissue inhibitors 1 and 2 in benign and malignant breast lesions: an in situ hybridization study

Invasive growth requires degradation of extracellular matrix. Altered expression of matrix degrading enzymes may indicate an increased potential for invasive growth. We determined the expression patterns of matrix-metalloproteinases (MMP)-1, -2, and -3 and of the tissue inhibitors of metalloproteinases (TIMP)-1 and -2 by in situ hybridization with isotopically labeled RNA probes in normal breast tissue (n=6), fibrocystic disease (n=20), five cases of which contained radial scars, lobular carcinoma in situ (CLIS; n=5), ductal carcinoma in situ (DCIS; n=9) and invasive carcinomas (n=24). Only a few cells displayed MMP-1- and MMP-2-specific labeling in normal breast tissue and fibrocystic disease. Noninvasive ductal carcinomas showed elevated MMP-2 transcript levels in peritumor stromal cells in the absence of significant MMP-1 specific signals. In general, compared with adjacent normal breast tissue, a gradual increase of MMP-2 was found in noninvasive to invasive cancers. Invasive ductal and lobular carcinomas displayed co-expression of MMP-1 and MMP-2 by stromal cells, mainly of the invasion front, with high signal intensity particularly in high-grade invasive carcinomas. Tumor cells and peritumor stroma showed low MMP-3 transcript levels, especially in medullary carcinomas. TIMP-1 and -2 transcript levels were increased in invasive carcinomas correlating with the histological grade. These RNA expression patterns suggest an increased invasive potential in breast carcinomas even prior to histologically overt invasive growth.

Detection of human papillomavirus type 16 DNA in carcinomas of the palatine tonsil

Twenty eight tonsillar carcinomas of various histological types were investigated for the presence of Epstein-Barr virus (EBV), cytomegalovirus (CMV), and human papillomavirus (HPV) types 6, 11, and 16 by in situ hybridisation using highly stringent procedures. In six cases an autoradiographic signal was obtained in the tumour cell nuclei with the HPV type 16 specific probe. No signal was obtained with any of the other probes. Immunohistochemical investigations with mouse monoclonal antibodies directed against the L1 protein of HPV type and a rabbit antiserum that detects common protein determinants of HPV gave negative results, thus indicating latent infection. Furthermore, a series of tonsils from controls with comparable age distribution was negative by both in situ hybridisation and immunohistology. These results indicate a possible role for HPV 16 in the aetiology of a proportion of tonsillar carcinomas.

Epstein-Barr virus and carcinomas: rare association of the virus with gastric adenocarcinomas

We have analysed 174 gastric carcinomas from the United Kingdom and from Japan for the presence of Epstein-Barr virus (EBV) using in situ hybridisation for the small EBV-encoded nuclear RNAs (EBERs). EBV was detected in the tumour cells in all of six undifferentiated gastric carcinomas with prominent lymphoid stroma (undifferentiated carcinomas of nasopharyngeal type, UCNT) but only in three of the remaining 168 typical gastric adenocarcinomas (1.8%). No differences were observed between the British and the Japanese cases. One case with an EBV-positive UCNT showed adjacent areas of EBV-negative typical adenocarcinoma. It is uncertain whether these patterns represent two independent carcinomas or whether they are the result of heterogeneous EBV infection in a single tumour. In the remaining EBV-positive carcinomas, viral transcripts were detected in virtually all tumour cells, indicating that EBV infection must have taken place early in the neoplastic process and suggesting that the virus is likely to be of pathogenetic significance for the virus-associated tumours. Immunohistology demonstrated absence of detectable levels of the EBV-encoded latent membrane protein, LMP1, and nuclear antigen, EBNA2. The BZLF1 protein which induces the switch from latent to lytic infection was demonstrated in a small proportion of the tumour cells in three cases. The close association of EBV with undifferentiated gastric carcinomas compared to the variable association with gastric adenocarcinomas suggests fundamentally different roles for the virus in the aetiology of these two malignancies.

Identification of Epstein-Barr virus-infected cells in tonsils of acute infectious mononucleosis by in situ hybridization

In situ hybridization with 35S-labeled Epstein-Barr virus (EBV) probes was applied to paraffin sections of tonsils from seven patients with clinical, serologic, and morphologic evidence of acute infectious mononucleosis. EBV genomes were demonstrated in activated lymphoid B blasts in the interfollicular and perifollicular zones in all these cases. However, in no case could EBV be identified in epithelial cells. These results are at variance with the current concept which attributes a central role to the tonsillar epithelium in primary EBV infection.

Comparable expression of matrix metalloproteinases 1 and 2 in pouchitis and ulcerative colitis

BACKGROUND AND AIMS

Matrix metalloproteinases (MMPs) are implicated in the tissue destruction associated with inflammatory diseases. Proctocolectomy with ileo-anal pouch (IAP) anastomosis is associated with pouchitis, particularly in patients with ulcerative colitis (UC). The aim of this study was to quantify MMP-1 and MMP-2 in inflamed and uninflamed pouches of patients with UC compared with those with active UC. IAP patients with familial adenomatous polyposis (FAP) served as controls.

METHODS

Biopsies were taken from 33 patients with IAP (UC, n=25; FAP, n=8) and from 10 UC patients. MMP-1 and MMP-2 were quantified using sandwich enzyme linked immunosorbent assays. In addition, northern and western blotting and in situ hybridisation experiments were performed.

RESULTS

In pouchitis (n=11), MMP-1 and MMP-2 concentrations were increased compared with uninflamed pouches of patients with UC (n=14) or FAP (n=8) (MMP-1 17.7 ng/mg protein v 7.8 (UC) v 7.6 (FAP), p</=0.05; MMP-2 16.4 v 9.5 (UC) v 6.3 (FAP), p</=0.05). Western and northern blots revealed increased MMP-1 and MMP-2 protein and transcript concentrations in inflamed pouches. Mesenchymal cells were identified as major producers of MMP-1 and MMP-2 in pouchitis. A similar increase in MMPs was observed in tissues of patients with active UC.

CONCLUSIONS

Our results support the hypothesis that MMPs are involved in mucosal destruction and crypt hyperplasia, as seen in pouchitis.

Lymphotoxin, tumour necrosis factor and interleukin-6 gene transcripts are present in Hodgkin and Reed-Sternberg cells of most Hodgkin's disease cases

Tissue specimens from 26 cases of Hodgkin's disease (HD) and six HD-derived cell lines were analysed for tumour necrosis factor (TNF), lymphotoxin (LT), and interleukin (IL)-6 RNA transcripts by in situ hybridization, in some cases subsequent to immunohistology for CD30 antigen. LT and TNF transcripts were found in tumour cells of all cases; IL-6 gene transcripts were detectable in 19/23 cases. Presence of RNA specific for these cytokines was not correlated with any of the following parameters: sex, symptoms and histotype, as well as immunophenotype and association of the tumour cells with Epstein-Barr virus. Rather, the presence of LT, TNF and IL-6 transcripts appeared to characterize Hodgkin and Reed-Sternberg cells in general, supporting concepts which suggest that HD represents a malignancy of cytokine secreting activated cells, and that many of the features distinguishing HD from other malignant lymphomas may ultimately be due to expression of cytokines. LT and TNF RNA transcripts were also found in five HD-derived cell lines, whereas supernatants of these cell lines contained high levels of LT, but low or undetectable levels of TNF activity. This suggests that, although not detectable at the level of RNA transcripts, differences between HD cases may exist on the level of cytokine gene transcript processing, translation and polypeptide secretion.

Cellular localization of procollagen gene transcripts in inflammatory bowel diseases

The cellular localization of procollagen types I, III, IV, and V gene transcripts was determined in tissues from 12 patients with either Crohn's disease (CD) or ulcerative colitis (UC) and nine controls by in situ hybridization with 35S-labeled RNA probes. In CD, the signal intensity and number of labeled cells were significantly increased, particularly in deeper intestinal layers. In contrast, the labeled cells in UC were concentrated in the subepithelial intestinal layers, with an overexpression of procollagen III RNA transcripts. Immunohistological stainings for procollagen types I, III, and IV showed a weaker staining in UC than in CD, indicating that increased transcript levels in UC are unrelated to the enhanced collagen protein deposition, although the increase of procollagen messenger RNA levels correlated with the density of the inflammatory infiltrate. It was concluded that both CD and UC show highly increased procollagen RNA transcript levels but differ in collagen deposition. Thus, different posttranscriptional or posttranslational regulatory mechanisms, such as collagen degradation, may account for the observed differences.