Human intestinal development in a severe-combined immunodeficient xenograft model

The present work describes a severe-combined immunodeficient murine xenograft model used to investigate human gastrointestinal ontogenesis. Specifically, the study has tested whether carefully selected regions of human fetal gut are able to undergo region-specific morphogenesis and epithelial cytodifferentiation when transplanted subcutaneously into immunodeficient mice. In addition, double-label in situ hybridisation techniques, utilising specific human and mouse DNA probes, have been adopted to characterise host and donor cell types and to investigate the potential developmental roles for non-epithelial cells in the regulation of epithelial differentiation pathways in vivo. Human fetal small and large bowel developed to form a characteristic mucosa 10 weeks after transplantation, which displayed clear region-specific structural and functional gradients. The initial phase of xenograft epithelialisation closely resembled the stratified type of epithelium which is present during early fetal gastrointestinal development. Idiosyncratic epithelial differentiation pathways were recorded during xenograft regeneration, with an absence of Paneth cells and an abundance of enteroendocrine cells when compared with developed xenograft and paediatric intestine. Such differences may, therefore, be important in ensuring rapid and region-specific development in the absence of conventional luminal stimuli and hormonal changes that occur normally during pregnancy. In situ hybridisation demonstrated an exclusively human origin for the intestinal xenograft epithelium and muscularis mucosa and externa. Although the submucosa and lamina propria were comprised of a chimeric mixture, murine cells were rarely seen to contact with the epithelium, which interacted primarily with human myofibroblasts and human intraepithelial lymphocytes. It is proposed that a 'selection' process operates to maintain species-specific cellular interactions, and this mechanism may subsequently play an important role in regulating epithelial cell differentiation, orchestrated in part by juxtaposed non-epithelial cell types.

Application of a polymorphic Y microsatellite to the detection of post bone marrow transplantation chimaerism

A highly sensitive Y-microsatellite amplification system was developed for the detection of post bone marrow transplantation (BMT) chimaerism. The system is able to detect the DNA equivalent of a single male cell in a background of 10(5) female cells. For clinical applications it has the distinct advantage that the polymorphic nature of the PCR product allows the checking of the genuineness of a positive PCR signal by reference to its allelic type. This extra degree of precision enhances the accuracy of Y-PCR for clinical diagnosis.

High prevalence of pancreatic islet amyloid in patients with end-stage renal failure on dialysis treatment

Islet amyloid polypeptide (IAPP) is the main proteinaceous component of pancreatic islet amyloid, which is a characteristic feature of type 2 diabetes. The factors responsible for amyloid deposition are unclear. Patients with end-stage renal failure (ESRF) on dialysis treatment have increased insulin resistance which is associated with hypersecretion of beta-cell products. Furthermore, elevated concentrations of circulating IAPP are found in these patients due to reduced renal clearance of IAPP. To determine the prevalence of islet amyloid in this group of patients, pancreas was examined from 23 non-diabetic [aged 62 (29-79) years, median and range] and four type 2 diabetic [aged 67 (56-72) years] patients with ESRF on dialysis treatment. Pancreatic specimens from 30 non-diabetic control subjects [aged 67.5 (56-86) years] and 14 type 2 diabetic subjects without renal disease [aged 69 (48-86) years] were used as control groups. Islet amyloid was present in all type 2 diabetic patients with ESRF and in 12 out of 14 type 2 diabetic control subjects (86 per cent). Amyloid deposits were found in 8 out of 23 non-diabetic patients with ESRF (35 per cent), which was a higher prevalence than that found in non-diabetic control subjects (3 per cent) (P < 0.01). This may be related to undiagnosed (pre)diabetes. Elevated secretion rates of IAPP due to insulin resistance and high circulating IAPP concentrations as a result of severely reduced renal clearance of IAPP will cause high pericellular concentrations of IAPP. This condition is likely to enhance amyloid fibril formation in pancreatic islets similar to that observed in type 2 diabetes.

Acute hepatitis C infection after sexual exposure

A case is described of a woman with acute hepatitis C infection whose partner had chronic hepatitis C infection and where heterosexual contact was the only major risk factor. Infection of both partners was confirmed serologically and by the finding of virus RNA by reverse transcription and polymerase chain reaction amplification. Nucleotide sequence analysis of the NS5 region (RNA polymerase) was used to show that both partners were infected with virus of the same genotype (1a). The nucleotide sequence of virus RNA found in the female patient is closest to variants cocirculating in the male contact, consistent with transmission having occurred between the two.

Combined immunocytochemistry and non-isotopic in situ hybridization for the ultrastructural investigation of human parvovirus B19 infection

Parvovirus B19 is a single-stranded DNA virus with a specific tropism for human erythroid precursor cells. The virus codes for two overlapping structural (capsid) proteins and one non-structural protein which is thought to perform essential functions in viral replication, transcription and packaging. The ultrastructural localization of these proteins was achieved in cultured haemopoietic cells derived from fetal liver which had been infected in vitro and subsequently embedded in LR White acrylic resin. Postembedding immunogold detection of B19 structural and non-structural proteins was combined with localization of viral nucleic acid by in situ hybridization using a digoxigenin-labelled probe and different sized gold labels. The majority of the B19 capsid protein and DNA present in cells harvested 48 hours post-infection co-localized within the centri-nuclear region of erythroid cells demonstrating characteristic chromatin margination. Relatively little DNA hybridization signal was present over paracrystalline inclusions strongly labelled with anti-capsid protein monoclonal antibody R92F6. Viral DNA and capsid protein were co-localized in apparent egress from the nucleus through nuclear pores. B19 non-structural protein was detected in association with both nuclear and cytoplasmic arrays of capsids, supporting the view that this protein plays an important role in viral packaging and remains associated with the complete viral particle until its release from the cell. Co-localization of viral nucleic acid and proteins at the ultrastructural level is a flexible, rapid and highly specific tool for examination of viral life-cycles within cells.

Role of human papillomavirus in determining the HLA associated risk of cervical carcinogenesis

AIMS

To investigate the role of human papillomavirus (HPV) in the association between HLA DQw3 and squamous cell cancer of the cervix (SCCC).

METHODS

Tissue from 194 cervical samples, ranging from normal, through cervical intraepithelial neoplasia, to SCCC, were typed for HPV by amplification of the L1 gene using degenerate consensus primers, followed by oligonucleotide probing. HLA DQw3 typing was undertaken in the same samples using a new PCR amplification system using primers common to all DQ loci, followed by restriction digestion with Mlu 1 to differentiate HLA DQw3 types--null, heterozygous, and homozygous. The data were analysed using chi 2 analysis and by calculating relative risks with the 95% confidence interval.

RESULTS

Samples (n = 188) were successfully typed for HPV and 177 were typed for HLA DQw3. There was a nonsignificant rise in the prevalence of HLA DQw3 in SCCC (64.3%) compared with the group with normal histology (53.2%). Analysis of the prevalence of HLA DQw3 on the basis of HPV infection rather than histology showed that 63 of 95 (66.3%) of the HPV positive samples contained HLA DQw3 alleles, compared with 39 of 78 (50.0%) of the HPV negative samples (chi 2 4.06; p < 0.05).

CONCLUSIONS

There was a significant association between HLA DQw3 and cervical HPV infection. This may be because people with HLA DQw3 are less able to mount an effective immune response to HPV, which predisposes them to the development of SCCC.

A 2-year follow-up study of anti-neutrophil antibody in primary sclerosing cholangitis: relationship to clinical activity, liver biochemistry and ursodeoxycholic acid treatment

A specific anti-neutrophil antibody was recently described in primary sclerosing cholangitis and was detected using an indirect immunoalkaline phosphatase method. The present study examined the relationship of this antibody with respect to time, clinical activity, liver biochemistry, histology and ursodeoxycholic acid treatment. Fourteen patients with primary sclerosing cholangitis were followed up at regular intervals for 2 years. Clinical activity, liver biochemistry, histology and anti-neutrophil antibody titre were determined during the study period. A fluctuating course of the anti-neutrophil antibody was noted in both untreated patients and in those who were on ursodeoxycholic acid. This finding will have clinical implications if anti-neutrophil antibody is used to screen for potential primary sclerosing cholangitis in the future. The results suggest that several determinations of the antibody would need to be carried out over a period of time. No correlation was found between the antibody titre, clinical activity, liver biochemistry or histology. Anti-neutrophil antibody in primary sclerosing cholangitis probably has no pathogenic significance and is an epiphenomenon.

Defining the immunogenetic susceptibility to primary biliary cirrhosis

Primary biliary cirrhosis is a chronic cholestatic disease, thought to be immune-mediated with genetic susceptibility encoded in the major histocompatibility complex. In northern Europeans, the best established associations are with HLA-DR8 and the complement allele, C4B2. These associations could be due to a single susceptibility locus on an extended haplotype linking HLA-DR8 and C4B2 or to both HLA-DR8 and C4B2 independently conferring disease susceptibility. C4B2 genotyping was performed on 64 patients with primary biliary cirrhosis and 61 controls matched for ethnic background and frequency of HLA-DR8. C4B2 was associated with HLA-DR8 (p < 0.05) in PBC. No difference in the frequency of C4B2 was detected between control and disease populations, suggesting that HLA-DR8 and C4B2 are in linkage disequilibrium and that C4B2 is not a susceptibility locus for PBC. Taq I polymorphisms were screened in the disease and control populations with the cosmid probe G91, located midway between the HLA-DR and complement loci. One G91 restriction fragment (G91A) was found to be associated with both HLA-DR8 and C4B2, at equal frequency in health and disease, providing evidence of an HLA-DR8-G91A-C4B2 extended haplotype. The frequency of G91A was the same in the disease and control populations, suggesting that G91A does not confer disease susceptibility. These findings establish G91 as the telomeric boundary for disease susceptibility associated with HLA-DR8, encoded on chromosome six. These studies help define the immunogenetic susceptibility locus for primary biliary cirrhosis.

Prenatal determination of fetal rhesus D status by DNA amplification of peripheral blood of rhesus-negative mothers

We have developed a sensitive PCR-based assay for the RhD gene and used it to detect circulating fetal cells from RhD-positive fetuses from peripheral blood of RhD-negative mothers. With further improvement in diagnostic accuracy, this assay may have implications in the management of RhD-sensitized pregnancies in women whose partners are heterozygous for the RhD gene. Further studies are required to determine the relationship between maternal anti-D levels and circulating fetal cell numbers.

Superficial thrombophlebitis, dysplasia, and cholangiocarcinoma in primary sclerosing cholangitis

Cholangiocarcinoma occurs in approximately 10% of patients with primary sclerosing cholangitis. Usually, liver failure, rapidly progressing jaundice, and an increase in alkaline phosphatase levels are suggestive diagnostic features. We report two cases of patients with primary sclerosing cholangitis who developed cholangiocarcinoma without jaundice and with no changes in their serum biochemistry. Both patients were taking ursodeoxycholic acid at the time of tumor diagnosis. Initial suspicion of malignancy was based on the development of superficial thrombophlebitis. Liver histology showed evidence of bile duct epithelial dysplasia in areas free from tumor in one patient, and in the other, bile duct epithelial dysplasia preceded the appearance of cholangiocarcinoma by at least 18 months. In one of the cases, the dysplastic epithelium stained positively for carcinoembryonic antigen. The histological finding of bile duct epithelial dysplasia in patients with primary sclerosing cholangitis may suggest either imminent or actual development of cholangiocarcinoma and may thus affect consideration of orthotopic liver transplantation. In addition, the development of superficial thrombophlebitis in patients with primary sclerosing cholangitis should arouse suspicion of the presence of cholangiocarcinoma even if there is no evidence of deterioration of the liver function or a dominant stricture on endoscopic retrograde cholangiography.

Detection of fetal RhD sequence from peripheral blood of sensitized RhD-negative pregnant women

A sensitive PCR-based assay was developed to amplify fetal-derived rhesus D (RhD) sequence from peripheral blood of RhD-negative pregnant women with circulating anti-D. RhD-PCR positivity was detected in 7/22 samples from women bearing RhD-positive fetuses, despite the presence of varying levels of anti-D. Evidence is presented which suggests that rising maternal anti-D levels might reduce circulating fetal cell numbers. Further development of this assay may have implications in the clinical management of RhD-sensitized pregnancies and aid the understanding of the physiology of feto-maternal cell trafficking.

HLA DR4 is a marker for rapid disease progression in primary sclerosing cholangitis

BACKGROUND/AIMS

Primary sclerosing cholangitis (PSC) is an inflammatory disease of the biliary tree associated with an increase in the HLA alleles DR3, DR52a, DR2, Dw2, and a decrease in DR4. However, it is not certain which of these alleles provides the primary associations. Our aim was to establish the primary HLA associations with PSC and to assess the ability of HLA alleles to mark for disease progression.

METHODS

By applying molecular techniques to archival tissue, we have genotyped 83 PSC patients from two populations and 131 controls for the alleles HLA DR2, DR3, DR4, DRw12, DR52a, and Dw2.

RESULTS

HLA DR3, DR52a, DR2, and Dw2 were all significantly increased in PSC, with the relative risk for DR52a and Dw2 being greater than for DR3 and DR2, respectively. HLA DR4 was significantly decreased, but this may be artifactual to the DR3, DR2 increase. HLA DR4 and not DR52a marks for rapid disease progression in both our PSC populations.

CONCLUSIONS

HLA DR52a and Dw2 are the best candidate alleles for providing the known HLA association with PSC. HLA DR4 and not DR52a marks for rapid disease progression in our two PSC populations.

Role of respiratory viral infection in SIDS: detection of viral nucleic acid by in situ hybridization

There is considerable evidence suggesting that respiratory viral infection is involved in the genesis of the sudden infant death syndrome (SIDS), with rates of about 20 per cent of SIDS victims compared to about 13 per cent of controls. Since the techniques used previously are prone to under-reporting from autopsy material, non-isotopic in situ hybridization (NISH) has been used to detect viral nucleic acid in lung in SIDS. Forty-five SIDS cases (30 males) were examined (age range 3 weeks-14 months, mean age 3.9 months). Thirty non-SIDS cases (15 males) were also examined (age range 5 weeks-24 months, mean age 9.0 months). Eleven of 45 (24.4 per cent) SIDS cases were positive by NISH compared to 1 of 30 (3.3 per cent) non-SIDS cases (P = 0.012). There were eight cases of adenovirus type 5, two cases of respiratory syncytial virus (RSV), and one case of parainfluenza virus type 2. The one positive control case was adenovirus type 5. Only lung parenchyma was examined here. Additional examination of the upper respiratory tract may increase the number of positive cases.

Detection of chimaerism after bone marrow transplantation using the double amplification refractory mutation system

We have developed a highly sensitive double amplification refractory mutation system (double ARMS) for the detection of extremely low levels of mixed chimaerism after bone marrow transplantation. The system we chose for double ARMS analysis is a highly polymorphic region 5' to the human delta-globin gene. Double ARMS analysis was found to correlate well with an established minisatellite system and was shown to demonstrate a very low level of mixed chimaerism in cases undetectable by the latter method.

Detection of reactivation and size variation in the regulatory region of JC virus in brain tissue

AIMS

To develop a sensitive and specific polymerase chain reaction (PCR) based system for detecting genomic variation in JC virus. To apply this system to formalin fixed, paraffin wax embedded brain tissue from patients with and without progressive multifocal leucoencephalopathy (PML).

METHODS

A pair of primers (JC1 and JC2) were designed to be complementary to the early and late regions of JC and BK polyomaviruses, respectively. A third primer (JC3), internal to JC1 and JC2, was designed to be specific for JC virus. The specificity of JC3 was investigated by amplifying plasmids with BK or JC virus genomes. Sensitivity was estimated by titration of a plasmid containing JC virus genome. Seven brains from patients with PML (PMLB) and 30 from patients without PML (non-PMLB) were amplified using JC1 and JC2, followed by JC1 and JC3. Amplification of the beta globin gene was used as an amplification control.

RESULTS

Amplification with JC1 and JC2 was common for JC and BK viruses, but with JC1 and JC3 it was specific for JC virus. The sensitivity of the system was 25 copies of JC plasmid per 10 microliters of digested tissue. Five out of seven PMLB and 28 of the 30 non-PMLB amplified for beta globin, but only the PMLB gave a signal with polyoma primers. Hypervariation of the length of the regulatory region of the JC isolates in the PML tissues was consistent with the presence of multiple strains of JC.

CONCLUSIONS

Variation in the regulatory region of JC virus can be specifically and sensitively detected from routinely processed, paraffin wax embedded brain tissue. Variation in the regulatory region is common in PML derived JC strains, but JC virus was not detectable in non-PMLB tissue.

Intracellular localization of parvovirus B19 nucleic acid at the ultrastructural level by in situ hybridization with digoxigenin-labelled probes

Conditions suitable for immunogold detection of digoxigenin-labelled DNA probes hybridized to parvovirus B19-infected erythroid cells embedded in Lowicryl K4M and LR White acrylic resins were established at the electron microscope level. The protocol was initially optimized using a positive control probe for whole human DNA which produced signal over the heterochromatin of all nucleated cells. In cultures harvested 2 days postinfection, B19 nucleic acid was detected mainly within the centrinuclear region of erythroid cells exhibiting characteristic margination of the chromatin. The B19 hybridization signal was largely unaffected by denaturation and was resistant to RNase digestion but sensitive to DNase digestion, indicating that it was mainly single-stranded B19 DNA. Relatively few gold particles were found over crystalline arrays of viral capsids, consistent with the observation that they are composed of mainly 'empty' capsids. B19 nucleic acid was detected in apparent transit from nucleus to cytoplasm through pores in the nuclear membrane. While the sensitivity of this system is limited by the fact that hybridization occurs only at the surface of the section, it is a rapid and specific means of localizing viral nucleic acids with a high degree of resolution.

Primary biliary cirrhosis: contribution of HLA class II allele DR8

Primary biliary cirrhosis is a chronic cholestatic disease of unknown aetiology which predominantly affects middle-aged women. It is thought to be autoimmune in nature, but unlike many autoimmune diseases no clear HLA association has been described. Several studies have suggested conflicting associations with HLA class II, although a DR8 association is most frequently described. To test the hypothesis that primary biliary cirrhosis is associated with a certain HLA class II locus we genotyped 130 patients with the disease from the north-east region of England and 363 local healthy controls. HLA-DRB1 and confirmatory DQA and DQB genotypes were determined by TaqI restriction fragment DNA length polymorphism analysis. In addition, a polymerase chain reaction technique (double ARMS) was used to investigate the DRB3 locus (DR52) in 98 primary biliary cirrhosis patients and 107 local controls. We found an increased frequency of HLA-DR8 (18.5% vs 9.2%, p < 0.005, relative risk of 2.0 [1.3-3.1]) in the primary biliary cirrhosis group. HLA-DR8-positive primary biliary cirrhosis patients had a higher serum bilirubin level (p = 0.03) than DR8-negative patients. There was no difference in the DR52 frequencies and no association with markers of disease severity. These results support earlier serological findings, although the association between primary biliary cirrhosis and DR8 is weaker than previously described. In addition, DR8-positivity may identify a clinical subgroup with a worse prognosis.