Mechanisms involved in Helicobacter pylori-induced inflammation

BACKGROUND

Helicobacter pylori infection is associated with mucosal inflammation. The aims of the present study were to assess whether a water extract of H. pylori promotes neutrophil (polymorphonuclear leukocyte [PMN]) adherence to endothelial cells and define the molecular basis of this adhesive interaction.

METHODS

Intravital microscopy was used to study leukocyte adhesive interactions in rat mesenteric venules in situ. PMN-endothelial cell adhesive interactions were studied in vitro using human PMNs and monolayers of human umbilical vein endothelial cells (HUVEC).

RESULTS

In vivo, superfusion of rat mesentery with the H. pylori extract increased leukocyte adhesion and emigration in venules. In vitro, adhesion of human PMNs to HUVEC was increased by the H. pylori extract in a concentration-dependent manner. Pretreatment of HUVEC alone with H. pylori extract had no effect on PMN adherence, whereas pretreatment of PMN alone significantly increased their adherence to HUVEC. The extract-induced adhesion was significantly diminished by monoclonal antibodies (MAb) directed against either CD11a, CD11b, or CD18 on neutrophils, and by MAbs against intercellular adhesion molecule-1 (ICAM-1), but not E- or P-selectin, on endothelial cells.

CONCLUSIONS

These studies suggest that products of H. pylori elicit gastrointestinal inflammation by promoting PMN adhesion to endothelial cells via CD11a/CD18- and CD11b/CD18-dependent interactions with ICAM-1.

Non-penetrance and late appearance of polyps in families with familial adenomatous polyposis

One case of non-penetrance of the familial adenomatous polyposis (FAP) gene at 59 years of age and late onset of polyps on endoscopy and biopsy in this and two other families is described. Screening protocols should include dental screening as well as indirect ophthalmoscopy and endoscopy to detect minimal manifestations of the gene. In the absence of a specific DNA predictive test, bowel screening should continue well beyond 30 years of age.

Assessment of relative risk of second primary tumors after ovarian cancer and of the usefulness of double primary cases as a source of material for genetic studies with a cancer registry

BACKGROUND

It now is accepted that a small proportion of people with certain forms of cancer have a dominantly inherited gene fault that predisposes them to it. This is more likely with an early age at onset or when the person has had multiple primary tumors.

METHODS

Population-based data from the North West Regional Cancer Registry of England regarding 4157 ovarian cancer cases diagnosed between 1980 and 1989 were analyzed to determine the relative risks (RR) of second primary breast and colorectal carcinomas.

RESULTS

Elevated risks approaching significance were observed for breast and colorectal carcinoma subsequent to ovarian cancer. After stratification into groups for ovarian histopathologic characteristics and age at onset, significantly elevated risks were obtained for both breast and colorectal tumors after ovarian carcinoma for women younger than 60 years of age at onset and with serous histopathologic characteristics (breast RR, 2.68, P < 0.05; colorectal RR, 4.25, P < 0.05).

CONCLUSIONS

These results emphasize the need for greater awareness of the possibility of development of additional cancer after ovarian carcinoma in high-risk groups. Overall, the study supports the theory that breast, colorectal, and ovarian tumors are related genetically.

DNA-DNA hybridization demonstrates apparent genetic differences between Helicobacter pylori from patients with duodenal ulcer and asymptomatic gastritis

We asked whether different clinical outcomes of Helicobacter pylori infection might be a reflection of genetic differences in infecting organisms. Using DNA-DNA hybridization we examined whether hybridization levels grouped H. pylori isolates corresponding to the type of disease (gastric ulcer, duodenal ulcer, asymptomatic gastritis) from which they were recovered. Target DNAs were prepared from H. pylori strains cultured from gastric biopsy specimens of 25 patients; 5 with gastric ulcers, 9 with duodenal ulcers, and 11 from asymptomatic volunteers endoscopically proven not to have peptic ulcer disease. DNA-DNA hybridization was performed with whole genomic probes made from an isolate from each of the three disease categories. Using a DNA probe from an isolate from a duodenal ulcer patient, we found that isolates from patients with duodenal ulcer and nonulcer gastritis yielded significant differences in levels of hybridization. The levels of hybridization of DNA from H. pylori isolates from duodenal ulcer patients, gastric ulcer patients, and nonulcer gastritis controls were 85.5% +/- 7%, 83% +/- 3%, and 78.3% +/- 5%, respectively (mean +/- SD), and the difference between the hybridization levels obtained with duodenal ulcer and nonulcer control target DNAs was statistically significant (P = 0.025). These data suggest that the outcome of infection (eg, ulcer or no ulcer) may be due to virulence factors encoded by genomic DNA. If such differences exist, it should be possible to produce probes that would identify the ulcer virulence gene(s) and clearly distinguish between ulcerogenic and nonulcerogenic strains of H. pylori.

Complications of the naevoid basal cell carcinoma syndrome: results of a population based study

There are many potential complications which have been reported in association with the naevoid basal cell carcinoma syndrome. We have been able to show the relative frequencies of these problems in a population based study of 84 cases in the north west of England. The major complications of basal cell carcinomas and jaw cysts occur in over 90% of patients by 40 years of age, but may both occur before 10 years of age. Less well described complications are ovarian calcification or fibroma (24%), medulloblastoma (5%), cardiac fibroma (3%), cleft palate (5%), and ophthalmic abnormalities such as squint or cataract (26%). This study more clearly defines the possible complications of the syndrome and gives clearer guidelines for counselling and screening affected and at risk persons.

Type 2 neurofibromatosis: the need for supraregional care?

The results of a U.K. study of 145 cases of type 2 neurofibromatosis has shown generally very poor operative results in terms of hearing and facial nerve preservation. Only 9 out of 118 vestibular schwannoma (acoustic neuroma) operations resulted in any clinically detectable hearing preservation and only 32 left the patient with good or normal (House grade I or II) ipsilateral facial nerve function. Although operation is still the definitive treatment of vestibular schwannoma (acoustic neuroma) and may be a lifesaving procedure, it appears that the evidence in favour of early operation is only valid when carried out in highly specialized centres. The special problems of NF2 cases who may go on to develop multiple spinal and cranial tumours making them wheelchair bound and blind as well as deaf warrants a careful experienced approach. Timing of operations may be critical for the enhancement of useful years of quality life. We therefore propose the setting up of a national NF2 register, with the management of cases at a few supraregional centres.

A linkage study in seven breast cancer families

Seven breast cancer families are examined for evidence of linkage to a site in the region of 17q12-q21, by using five markers. The families constitute a subset of a larger series of familial breast cancer; the seven families were selected because constitutional DNA was available on informative members, either from clinical samples or extracted from paraffin blocks. Two-point lod scores are reported. The maximum lod score, 0.8824, is obtained with marker NM23 at theta = 0. This is clearly not significant in itself; however, when taken in context with evidence from existing reports, it provides support for linkage to this region.

Perception of risk in women with a family history of breast cancer

We present the findings of a pilot study to assess the perception of risk in 155 women with a family history of breast cancer by questionnaire. Only 11% of women were able to identify the correct population risk and more than half were unable to assess their own lifetime risk within 50% of the clinicians' estimate. Although it is probable that women are helped by genetic counselling and if at substantial risk, annual mammography, the psychological impact of assigning true risk and the value of mammography need to be evaluated.

Cloning, nucleotide sequence, and expression of a gene encoding an adhesin subunit protein of Helicobacter pylori

Gene hpaA, which codes for the receptor-binding subunit of the N-acetylneuraminyllactose-binding fibrillar hemagglutinin (NLBH) of Helicobacter pylori, was cloned and sequenced. The protein expressed by hpaA, designated HpaA, was identified as the adhesin subunit on the basis of its fetuin-binding activity and its reactivity with a polyclonal, monospecific rabbit serum prepared against NLBH purified from H. pylori. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and Western blots (immunoblots) showed that the cloned adhesin has the same molecular weight (20,000) as that found on H. pylori. Also, HpaA contains a short sequence of amino acids (KRTIQK) which are all either identical or functionally similar to those which compose the sialic acid-binding motif of Escherichia coli SfaS, K99, and CFA/I. Affinity-purified antibody specific for a 12-residue synthetic peptide that included this sequence blocked the hemagglutinating activity of H. pylori and was shown by immuno-gold electron microscopy to react with almost transparent material on unstained H. pylori cells, which is consistent with previous observations concerning the location and morphology of the NLBH.

A clinical, genetic and audiological study of patients and families with bilateral acoustic neurofibromatosis

The neurofibromatoses consist of at least two distinct autosomal dominant hereditary disorders. Neurofibromatosis type 1 (NF1) is due to a lesion on chromosome 17q. Neurofibromatosis type 2 (NF2) is caused by a defect on chromosome 22q. The hallmark of NF2 is the development, in the second and third decades, of bilateral acoustic neuromas. NF1 is characterized by the appearance of café-au-lait spots and neurofibromas in addition to iris hamartomas, or Lisch nodules, of the eye, during the first and second decades. Ten families were personally studied. A total of 16 members were found to be affected with NF2. A protocol for evaluation and review of subjects and relatives of NF2 families is proposed. A team approach, coordinating the expertise of multiple specialties is recommended.

Helicobacter pylori infection in dental workers: a seroepidemiology study

The finding of Helicobacter pylori in dental plaque suggested that dental workers may be at increased risk of acquiring H. pylori infection from occupational exposure. A cross-sectional survey of 239 dental workers from 37 Texas cities (including 89 dentists, 44 dental hygienists, 98 dental assistants, and eight dental students) was conducted. H. pylori infection was determined by the presence of IgG antibodies to H. pylori, using a specific and sensitive ELISA. Participants ranged in age from 19 to 72 yr (mean 34 yr) and the duration of dental practice ranged from 1 to 48 yr (mean 12 yr). Type of dental occupation, duration of practice, type of practice (public or private), instrument used for cleaning teeth (ultrasonic scaler or curette), and prevalence of upper gastrointestinal symptoms were determined by self-administered questionnaires and interviews. Eighty-two percent had no symptoms referable to the upper gastrointestinal tract. The overall prevalence of H. pylori infection was 24%: 17% in dentists, 18% in dental hygienists, 34% in dental assistants, and 25% in dental students. The prevalence increased significantly with age (p < 0.05). The prevalence of H. pylori infection was significantly higher in non-whites, 29 of 63 (46%), than whites, 29 of 176 (16%) (p < 0.001). Logistic regression analysis (dependent variable H. pylori) revealed no significant association between H. pylori infection and the type, duration, or volume of practice, or the type of cleaning instrument used. We conclude that dental workers are not at increased risk to H. pylori infection.

A genetic study of type 2 neurofibromatosis in the United Kingdom. II. Guidelines for genetic counselling

The major defining features, age at onset of symptoms, and survival in 150 patients with type 2 neurofibromatosis (NF2) have been studied. The mean age at onset was 21.57 years (n = 110) and no cases presented after 55 years of age. Patients presented with symptoms attributable to vestibular schwannomas (acoustic neuroma), cranial meningiomas, and spinal tumours. In 97 cases studied personally by the authors, skin and eye examination were found to be useful to detect early signs of the condition. Examination of the skin is likely to assist in early diagnosis in at least 10% of cases and examination of the eye for a lens opacity or cataract in at least as many again. There are marked interfamilial differences in disease severity and tumour susceptibility. Vestibular schwannomas are not fully penetrant, but the condition is usually expressed in another way. Alteration to the current diagnostic criteria is advocated to cover the lack of provision for new mutations. A screening protocol is proposed and the effect of disease heterogeneity on management is discussed.

A genetic study of type 2 neurofibromatosis in the United Kingdom. I. Prevalence, mutation rate, fitness, and confirmation of maternal transmission effect on severity

A clinical and genetic study of type 2 neurofibromatosis (NF2) has been carried out in the United Kingdom. Virtually complete ascertainment of cases in the north-west of England was achieved and suggests a population incidence of 1 in 33,000 to 40,000. In the UK as a whole, 150 cases have been identified and been used to study the clinical and genetic features of NF2. The autosomal dominant inheritance of NF2 was confirmed, 49% of cases were assessed as representing new mutations, and the mutation rate was estimated to be 6.5 x 10(-6). Evidence to support a maternal gene effect was found in that age at onset was 18.17 years in 36 maternally inherited cases and 24.5 in 20 paternally inherited cases (p = 0.027). The preponderance of maternally inherited cases was also significant (p = 0.03). Data are presented which suggest that there are two types of NF2, one with later onset and bilateral vestibular schwannomas as the only usual feature, and the other with earlier onset and multiple other tumours. A considerable number of cases did not fall easily into one or other group and other factors such as maternal effect on severity and anticipation need to be considered.

Allele losses in the region 17q12-21 in familial breast and ovarian cancer involve the wild-type chromosome

A predisposing gene for breast and ovarian cancer has recently been mapped to chromosome 17q12-21. If this gene is a tumour suppressor gene, allele losses would be expected in the tumours of affected family members and the losses should affect the wild-type chromosome, reflecting the need for inactivation of the wild-type allele at the predisposing locus. In four multiple case breast-ovarian cancer families, we have found that in each of nine tumours which showed allele losses, the losses were from the wild-type chromosome. This suggests that the putative 'breast-ovarian' cancer gene is indeed a tumour suppressor gene.

Helicobacter pylori in Hispanics: comparison with blacks and whites of similar age and socioeconomic class

Helicobacter pylori infection is twice as frequent in blacks as in whites. It has been postulated that the apparent increase in susceptibility to H. pylori infection in blacks might have a genetic basis. A case-control seroepidemiologic study of H. pylori prevalence was performed in 108 healthy Hispanic volunteers. Eighty-nine Hispanics were matched (1:1:1) with blacks and whites for age and socioeconomic status. There was an inverse correlation between H. pylori infection and educational level that remained after logistic regression analysis adjusting for age and sex. The adjusted prevalence of H. pylori infection was almost identical in Hispanics and blacks and significantly higher than in whites. Because Hispanics do not constitute a race, the increased prevalence of H. pylori in Hispanics and blacks is unlikely to be genetic. It is speculated that the unrecognized bias is a reflection of a generation cohort phenomenon related to the generational distance from very low socioeconomic status, i.e., the prevalence of H. pylori in Hispanics and blacks is currently lower than that of their parents but higher than that of the white population, which has experienced higher socioeconomic status for several generations.

Selection of the chimpanzee over the baboon as a model for Helicobacter pylori infection

Baboons (Papio sp.) and chimpanzees (Pan troglodytes) were screened for the presence of Helicobacter pylori. The gastric mucosae of the baboons were colonized by large spiral bacteria. However, a group of adult chimpanzees were identified that were free of spiral gastric bacteria, with five animals being recruited into an H. pylori challenge study. These animals were inoculated orogastrically with one of four strains of H. pylori and followed for up to 26 weeks. H. pylori was established in one of these animals during a primary challenge and in two other animals on secondary challenge. It was shown that the chimpanzee can be infected with H. pylori and that the inflammatory response in these animals mimics that seen in humans. Infection was marked by an antibody response to H. pylori-specific antigens in two animals. It was observed that H. pylori antibody-negative chimpanzees had no apparent infection by H. pylori or related bacteria. Thus serological screening of chimpanzees can be used to identify candidate animals for further evaluation.

A clinical study of type 2 neurofibromatosis

The clinical features, age at onset of symptoms and survival of 150 patients with type 2 neurofibromatosis were studied. The mean age at onset was 21.57 years (n = 110) and no patients presented after 55 years of age. Patients presented with symptoms attributable to vestibular schwannomas (acoustic neuroma), cranial meningiomas and spinal tumours. In 100 patients studied personally by the authors 44 per cent presented with deafness and this was unilateral in the majority (35/44). Deafness was accompanied by tinnitus in a further 10 per cent and muscle weakness or wasting was the first symptom in 12 per cent. Less common presenting symptoms were seizures (8 per cent), vertigo (8 per cent) numbness and tingling (2 per cent) and blindness (1 per cent). Eleven patients were diagnosed asymptomatically through screening. Café au lait spots occurred in 43 per cent (n = 43) but only one case had six. Skin tumours were detected in 68 per cent (68/100) and 38 per cent (34/90) had an identifiable lens opacity or cataract. The mean age at death in 40 cases was 36.25 years and all but one death was a result of a complication of neurofibromatosis. There are marked inter-family differences in disease severity and tumour susceptibility.

Ovarian cancer family and prophylactic choices

A subject from a family with ovarian cancer who has developed bilateral medullary carcinoma of the breast at the age of 40 is presented. The family is consistent with dominant inheritance of ovarian cancer and 12 female family members at 12.5%, 25%, and 50% risk, including our case, have undergone bilateral prophylactic oophorectomy and been given hormone replacement therapy. Despite the risk of further primary tumours of the breast our patient chose to have treatment with wide excision and radiotherapy. The implications for screening, prophylaxis, and hormone replacement therapy for this family are discussed.

Urease-associated heat shock protein of Helicobacter pylori

Helicobacter pylori urease is an extracellular, cell-bound enzyme with a molecular weight of approximately 600,000 (600K enzyme) comprising six 66K and six 31K subunits. A 62K protein is closely associated with the H. pylori urease, both in crude preparations and after gel filtration; this protein can be removed from the urease by ion-exchange chromatography without inactivating the enzyme. We purified this urease-associated protein and determined its N-terminal amino acid sequence. The sequence is 80% homologous (identical plus conserved amino acid residues) to the Escherichia coli GroEL heat shock protein (HSP), 75% homologous to the human homolog, and 84% homologous to the HSP homolog found in species of Chlamydia. Thus, the 62K urease-associated protein of H. pylori belongs to the HSP60 family of stress proteins known as chaperonins. Evidently this protein, HSP62, participates in the extracellular assembly and/or protection of the urease against inactivation in the hostile environment of the stomach.

Effect of treatment of Helicobacter pylori infection on the long-term recurrence of gastric or duodenal ulcer. A randomized, controlled study

OBJECTIVE

To determine the effect of treating Helicobacter pylori infection on the recurrence of gastric and duodenal ulcer disease.

DESIGN

Follow-up of up to 2 years in patients with healed ulcers who had participated in randomized, controlled trials.

SETTING

A Veterans Affairs hospital.

PARTICIPANTS

A total of 109 patients infected with H. pylori who had a recently healed duodenal (83 patients) or gastric ulcer (26 patients) as confirmed by endoscopy.

INTERVENTION

Patients received ranitidine, 300 mg, or ranitidine plus triple therapy. Triple therapy consisted of tetracycline, 2 g; metronidazole, 750 mg; and bismuth subsalicylate, 5 or 8 tablets (151 mg bismuth per tablet) and was administered for the first 2 weeks of treatment; ranitidine therapy was continued until the ulcer had healed or 16 weeks had elapsed. After ulcer healing, no maintenance antiulcer therapy was given.

MEASUREMENTS

Endoscopy to assess ulcer recurrence was done at 3-month intervals or when a patient developed symptoms, for a maximum of 2 years.

RESULTS

The probability of recurrence for patients who received triple therapy plus ranitidine was significantly lower than that for patients who received ranitidine alone: for patients with duodenal ulcer, 12% (95% CI, 1% to 24%) compared with 95% (CI, 84% to 100%); for patients with gastric ulcer, 13% (CI, 4% to 31%) compared with 74% (44% to 100%). Fifty percent of patients who received ranitidine alone for healing of duodenal or gastric ulcer had a relapse within 12 weeks of healing. Ulcer recurrence in the triple therapy group was related to the failure to eradicate H. pylori and to the use of nonsteroidal anti-inflammatory drugs.

CONCLUSIONS

Eradication of H. pylori infection markedly changes the natural history of peptic ulcer in patients with duodenal or gastric ulcer. Most peptic ulcers associated with H. pylori infection are curable.

Adherence and internalization of Helicobacter pylori by HEp-2 cells

Helicobacter pylori colonizes the mucous layer of the stomach and the surface of gastric mucous cells. Although H. pylori is not generally thought of as invasive, it has been observed in the lamina propria and within vacuoles in the cytoplasm of epithelial cells. The authors report that isolates of H. pylori can enter into the cytoplasm of tissue culture epithelial cell lines such as HEp-2 cells. Intracellular uptake of H. pylori by HEp-2 cells is rapid and appears to require both the N-acetylneuraminyllactose-binding adhesin and another factor present only in living bacteria. Uptake of H. pylori was inhibited by ammonium chloride and chloroquine at concentrations that did not effect either adherence or bacterial viability. Dansylcadaverine, an inhibitor of receptor clustering and internalization, also inhibited uptake but not adherence of H. pylori. Uptake was completely inhibited when H. pylori and HEp-2 cells were incubated at 4 degrees C under conditions that did not effect bacterial adherence. Cytochalasin B, an inhibitor of phagocytosis, did not inhibit uptake. It is concluded that H. pylori is internalized either by receptor-mediated endocytosis or by a closely related pathway.

Location of gene for Gorlin syndrome

The Gorlin (naevoid-basal-cell-carcinoma) syndrome is an autosomal dominant disorder characterised by multiple naevoid basal-cell carcinomas, recurrent odontogenic keratocysts, skeletal anomalies, intracranial calcification, and developmental malformations. Characterisation of the gene that causes the syndrome may improve our understanding of the pathogenesis of other basal-cell carcinomas. By linkage analysis, we have shown that the gene is located on chromosome 9q22.3-q31; the most likely position is between DNA markers D9S12 and D9S53. Location of the gene for Gorlin syndrome offers the possibility that DNA markers can be used in risk estimation and presymptomatic identification of patients for surveillance.