Helicobacter pylori infection and gastric lymphoma

High incidence of other neoplasms in patients with low-grade gastric MALT lymphoma

BACKGROUND

Low-grade gastric MALT lymphoma is an uncommon tumour for which a close association with chronic Helicobacter pylori infection has been suggested. However, given the rarity of MALT lymphoma of the stomach despite the high prevalence of H. pylori infection, it seems plausible that genetic host factors might play a fundamental role in gastric lymphomagenesis.

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 83 patients with low-grade gastric MALT, all of whom resided in a geographic area (southern Switzerland and northern Italy) where the incidence of gastric tumours appears to be uncommonly high.

RESULTS

One or more additional cancers were observed in 17 of 83 patients (20%, 95% CI 12% to 31%) for a total of 23 tumours. Of these, 5 were diagnosed prior to, 12 concomitantly with, and 7 after the gastric MALT lymphoma. Eleven patients had a single additional solid tumour (13%, 95% CI 7% to 22%); 3 patients had non-Hodgkin's lymphoma and one had Hodgkin's disease. Multiple additional cancers were present in 3 cases. Nine of 83 patients have died and 8 of them of a second cancer.

CONCLUSIONS

Unexpectedly an extraordinarily large number of patients with other malignancies was observed in this series. The reasons for this finding are still unknown, but genetic alterations are speculated to play an important role.

Low-grade lymphomas: new entities and treatment concepts

Therapy for patients with low-grade lymphomas has never been standardized. Recently, new entities have been described which are included in the REAL classification, and whether these entities should be regarded as separate diseases is not yet clear. Regardless, three new developments in the management of patients with low-grade lymphomas deserve special attention for treatment programs in the future. First, it appears that patients with stage I, II, and III low-grade lymphomas may enjoy very prolonged disease-free intervals after treatment with combination chemotherapy and radiation therapy programs. Although investigators disagree on prognostic factors, new features, such as beta 2-microglobulin appear to predict results better than any other feature, and future studies should address this prognostic factor in assessing their results. Second, for patients with advanced stage disease, administration of interferon as maintenance therapy prolongs the disease-free interval, and use of this drug should be further investigated. Finally, molecular studies using PCR for bcl-2 may be clinically relevant in detecting residual disease in patients with follicular lymphomas, and future studies should focus on the value of eliminating the residual disease from blood and marrow.

Resolution of Helicobacter pylori-associated gastric lymphoproliferative disease in a child

A possible causative association between Helicobacter pylori infection and gastric lymphoproliferative disorders has recently been recognized. The case of a 14-year-old girl who was diagnosed with H. pylori gastritis and associated gastric lymphoproliferative disease of the low-grade mucosa-associated lymphoid tissue type is reported. The patient was treated only for the H. pylori infection (amoxicillin, bismuth, and metronidazole) without any adjuvant chemotherapy or surgery for her lymphoproliferative disorder. This treatment not only resulted in the eradication of the microorganism but also complete resolution of her lymphoproliferative disease. The patient was subsequently followed up for a period of 7 years. There has been no histological recurrence of H. pylori gastritis or gastric lymphoproliferative disease. It is believed that this is the first report to describe a long-term follow-up of an H. pylori-associated gastric lymphoproliferative disorder in a pediatric patient who was exclusively treated for H. pylori infection. The observations in this report suggest that H. pylori-associated low-grade gastric lymphoproliferative disease can be completely cured by eradicating the organism. Therefore, this therapeutic approach, combined with close follow-up, should be the treatment of choice in children with this associated condition before attempting more aggressive treatments, thus potentially avoiding chemotherapy and/or (partial) gastrectomy.

Helicobacter pylori as a risk factor for cancer

In 1985, gastric cancer was the second most common cause of cancer death in the world. The rapid decline in gastric cancer rates over the last few decades has been attributed to a decline in the prevalence of environmental risk factors for gastric cancer and/or an increase in the prevalence of protective factors. One such risk factor could be the bacterium Helicobacter pylori. Epidemiological studies have shown that areas with high gastric cancer rates often have a correspondingly high prevalence of H. pylori and prospective studies have shown that subjects with serological evidence of H. pylori infection were significantly more likely to go on to develop gastric cancer than those who did not. Helicobacter pylori itself does not appear to be either genotoxic or mutagenic. Infection is, however, associated with increased cell turnover, a chronic immune response accompanied by increased levels of reactive oxygen metabolites and a reduction in gastric levels of ascorbic acid, all conditions that could favour the development of cancer. Nonetheless, the majority of those who are infected with H. pylori do not go on to develop gastric cancer and other factors, such as the strain of the infecting organism or consumption of dietary antioxidants including vitamin C, could also affect the risk of cancer. Finally, it has been estimated that more than one third, and possibly as many as 90% of gastric cancers might be attributable to infection with H. pylori. Prevention and treatment of infection are, therefore, possible approaches to reducing gastric cancer rates. It is, however, unclear what, if any, effect eradication of the infection would have on an individual's risk of gastric cancer and, to date, anti-Helicobacter therapy has only been shown to be of potential benefit in the treatment of low grade gastric MALT lymphomas.

Protein Hpn: cloning and characterization of a histidine-rich metal-binding polypeptide in Helicobacter pylori and Helicobacter mustelae

Helicobacter pylori is a human gastrointestinal pathogen involved in gastritis, duodenal ulcers, and gastric neoplasia. This microorganism produces large amounts of a urease which, like all known ureases, has nickel in the active site. We have identified a protein in clinical isolates of H. pylori and an identical protein in the ferret pathogen Helicobacter mustelae that strongly binds Ni2+ and Zn2+. This protein has been named Hpn to emphasize its origins in H. pylori and its affinity for nickel. The encoding hpn gene, cloned and expressed in Escherichia coli ER1793, has an open reading frame (180 bp) that specifies a protein with a calculated molecular mass of 7,077 Da and with the same amino-terminal sequence as that of wild-type Hpn. The deduced sequence of Hpn consists of 60 amino acids, of which 28 (47%) are histidines. The hpn gene does not map with the urease gene cluster on the H. pylori chromosome. An Hpn-negative, isogenic H. pylori strain, generated by hpn gene deletion and grown on blood agar, had the same urease activity that wild-type cells did. Thus, the role of Hpn in helicobacters is unknown.

Helicobacter pylori-induced gastritis in the domestic cat

Helicobacter pylori has been cultured from the inflamed gastric mucosae of naturally infected cats; the lesions in H. pylori-infected cat stomachs mimic many of the features seen in H. pylori-infected human stomachs. To determine whether H. pylori-negative specific-pathogen-free cats with normal gastric mucosae were susceptible to colonization by this bacterium and whether gastritis developed after infections, four H. pylori-negative cats treated with cimetidine were orally dosed three times with 3 ml (1.5 x 10(8) CFU/ml) of H. pylori every 4 days. All four cats became persistently colonized as determined by gastric cultures and PCRs from serial gastric biopsy samples and necropsy samples at 7 months postinfection. H. pylori was not isolated from the two control cats, nor were their gastric tissues positive by PCR; one of the two cats had a few focal lymphocytic aggregates in the body submucosa, whereas the second cat had a normal gastric mucosa. All four H. pylori-infected cats had multifocal gastritis consisting of lymphoid aggregates plus multiple large lymphoid nodules, which were most noticeable in the antral mucosa. In addition, one H. pylori-infected cat had a moderate diffuse infiltration of polymorphonuclear leukocytes in the subglandular region of the antrum. H. pylori-like organisms were focally distributed in glandular crypts of the antrum. Two of the H. pylori-infected cats had significant (eightfold) increases over baseline in levels of immunoglobulin G H. pylori serum antibody. The H. pylori isolates from the four experimentally infected cats had restriction fragment length polymorphism patterns specific for the flaA gene that were identical to those of the inoculating strain. H. pylori readily colonizes the cat stomach and produces persistent gastritis.

Regression of primary gastric lymphoma of mucosa-associated lymphoid tissue type after cure of Helicobacter pylori infection. MALT Lymphoma Study Group

Lymphoma of gastric-mucosa-associated lymphatic tissue (MALT) type has been linked to infection with Helicobacter pylori. We investigated the effect on MALT lymphoma of eradicating H pylori infection. 33 patients with primary gastric low-grade MALT lymphoma associated with H pylori gastritis were treated with omeprazole (120 mg daily) and amoxycillin (2.25 g daily) for 14 days to eradicate H pylori. In addition to histology, PCR was used to examine proliferation of monoclonal B cells before treatment and during follow-up. All patients had at least two post-treatment examinations, and all became negative for H pylori, 2 after a second treatment course. On histology, 23 (70%) patients showed complete regression and 4 (12%) partial regression of lymphoma. 6 (18%) patients had no change after cure of H pylori infection. 1 was treated with chemotherapy. Of 5 treated surgically, 4 were found to have high-grade B-cell lymphoma on histology of the resected stomach and 1 a high-grade T-cell lymphoma. PCR showed complete disappearance of monoclonal B cells after cure of H pylori infection in 13 of 16 patients investigated. During median follow-up of 1 year no relapse of MALT lymphoma occurred. Low-grade primary gastric MALT lymphoma can completely regress after eradication of H pylori infection. However, longer follow-up is needed to clarify whether the remission is lasting.

[Helicobacter pylori infection in children]

Helicobacter pylori (Hp) is a pathogen of human gastric mucosa and is considered as the major cause of chronic gastritis and duodenal ulcer disease recurrence. The prevalence rate of Hp infection increases with age and is related to low socioeconomic status in childhood. Childhood appears to be a high-risk period for Hp infection. Clinical and histological features of Hp infection are variable and often moderate in children. This is probably due to both genetic and environmental factors. Abdominal pain is the most frequent symptom and is usually associated with a mild chronic gastritis. Serology, 13C-urea breath test, bacterial culture and histological examination of biopsy specimen can be used for the diagnosis of Hp infection. Eradication of Hp infection is difficult and indications and modalities of treatment need to be specified in children. A better knowledge of epidemiology and natural history of Hp infection in childhood should permit to answer these questions.

Rapid large-scale growth of Helicobacter pylori in flasks and fermentors

We developed procedures for large-scale cultivation of Helicobacter pylori in flasks and fermentors. Flasks incubated closed under a microaerophilic gas phase with a cotton plug covered by a plastic bag, followed by removal of the bag after 8 h, gave excellent growth. Growth in a 10-liter fermentor led to excessive foaming if the medium was sparged with gas; silicone- or polyglycol-based antifoaming agents were severely inhibitory. Use of fermentor surface gassing, first with a microaerophilic 6% oxygen gas mixture, then with air, and then with 95% oxygen, allowed the culture to grow to an A600 of 2.5 in < 24 h. This method was modified for scale-up to a 100-liter fermentor.

Primary renal non-Hodgkin's lymphoma. An unusual extranodal site

BACKGROUND

Primary renal non-Hodgkin's lymphoma (NHL) is rare. Because the renal parenchyma does not have lymphatics, the existence of this entity has been questioned. The goal of this study was to determine the clinical presentation, pathologic features, and disease course of patients with primary renal NHL and review the pertinent literature on this unusual extranodal NHL.

METHODS

All medical records from the Mayo Clinic from 1976 to 1992 with the diagnosis of renal NHL were retrospectively reviewed. One-hundred seventy-six cases were identified, five of which met the criteria for primary renal NHL. The clinical, pathologic, and radiographic features were reviewed in detail and are the basis of this report.

RESULTS

The median age at diagnosis of the five patients with primary renal NHL was 60 years (range, 52-63 years) with a male-to-female ratio of 2:3. All patients had flank pain as their initial presentation. Urinalysis was abnormal in only one patient. In three patients, the serum creatinine was elevated. Tumor histology was diffuse large cell in four cases; and small noncleaved non-Burkitt's in one. All five were B-cell immunophenotype. All patients received combination chemotherapy. Although the median survival for the group was only eight months, two remain in complete remission longer than 80 months from therapy. These two had total removal of macroscopic lymphoma and received combination chemotherapy and consolidation radiotherapy.

CONCLUSIONS

Primary renal non-Hodgkin's lymphoma does exist. Patients whose lymphomas were completely resected macroscopically and who received combination chemotherapy with consolidation radiation therapy had long disease free survival. Patients with bilateral renal involvement or no debulking of the renal lymphoma tended to have poorer survival.

Primary gastric lymphoma in clinical practice 1973-1992

This study assessed the presentation, treatment, and prognosis of primary gastric lymphoma in general hospital practice and its relation to infection with Helicobacter pylori. The number of patients that would on the current recommendations have been suitable for H pylori eradication therapy was also examined. All lymphomas were graded according to a standard classification of gut lymphoma into high and low grade disease. Forty five patients (mean age 65 years) were identified. The overall five year survival was 40% with a trend in favour of an improved prognosis for low grade and stage I disease. H pylori was present in 80%. Only one of 18 patients with a low grade mucosa associated lymphoid tissue tumour had mucosal disease alone, which responded to omeprazole and amoxycillin. All other patients had bulk disease. These patients were treated by surgery, chemotherapy or radiotherapy or a combination of these treatments. In district hospital practice, most cases of primary gastric lymphoma have bulk disease at presentation. Even in patients with low grade gastric lymphoma on histological examination, many on the current evidence would not be suitable for anti-H pylori therapy alone.

Gastric B-cell mucosa-associated lymphoid tissue (MALT) lymphoma. Clinicopathological study and evaluation of the prognostic factors in 143 patients

BACKGROUND

Gastric MALT lymphoma can be histologically classified into two groups, low-grade (LG) and high-grade (HG); however, their natural history is poorly understood. We have studied a large retrospective series aiming to confirm whether the histological groups confer different clinical features and behavior and to analyze the prognostic factors in these patients.

PATIENTS AND METHODS

A series of 143 gastric B-cell MALT lymphomas is reported. Eighty-four were low-grade lymphomas (LG) and 59 were high-grade lymphomas (HG). Median follow-up was 36 months. The clinical and analytical parameters of the 84 LG patients were compared with those of the 59 HG patients. In the patients who had been operated on, the pathological features (macroscopical patterns, tumor size, involvement of resection margins, degree of parietal invasion and involvement of abdominal lymph nodes and adjacent viscera) of the LG patients were compared with those of the HG patients. The sites of relapses were studied. In the 132 treated and followed-up patients the influence of the treatment and that of clinical, analytical and pathological features on survival were investigated with the Kaplan and Meier and log-rank tests. To identify the factors with independent influence on survival, a Cox model was fitted for the whole series and separately for 53 HG patients.

RESULTS

HG group differed from the LG group by a significantly higher frequency of weight loss at presentation, palpable abdominal mass, hepatomegaly, peripheral lymphadenopathy, elevated serum LDH, higher incidence of stage III-IV and tumor/mass patterns in the endoscopy and in the gastrectomy specimen. The tumor was significantly larger in the HG group than in the LG and the deeper invasion of the gastric wall, the higher frequency of infiltration of the abdominal lymph nodes and the visceral extension were also significant in the HG group. Complete remission (CR) was achieved in 91% of the patients of the LG group, but was significantly lower, 70%, in the HG group. Relapses occurred in the stomach and also in non-MALT sites. In 132 treated and followed-up patients, elevated serum LDH, absence of CR, HG group and stage III-IV were associated with a worse survival. In the Cox multivariate model, stage was the only variable influencing survival, although stage was related to the histological grade. In the HG group, stage was also an independent significant risk factor, whereas treatment with surgery, chemotherapy or both was not. In the 103 patients treated with surgery, a worse survival was associated with the involvement of the resection borders, depth of the infiltration of the gastric wall, dissemination to distant abdominal nodes and adjacent organs, but not with the addition of chemotherapy.

CONCLUSIONS

Histological classification into LG and HG separates distinctive groups of gastric MALT lymphoma that show striking clinical and prognostic differences. Besides histological grade, stage is the most important prognostic feature.

Development of a mouse model of Helicobacter pylori infection that mimics human disease

The human pathogen Helicobacter pylori is associated with gastritis, peptic ulcer disease, and gastric cancer. The pathogenesis of H. pylori infection in vivo was studied by adapting fresh clinical isolates of bacteria to colonize the stomachs of mice. A gastric pathology resembling human disease was observed in infections with cytotoxin-producing strains but not with noncytotoxic strains. Oral immunization with purified H. pylori antigens protected mice from bacterial infection. This mouse model will allow the development of therapeutic agents and vaccines against H. pylori infection in humans.

Mucosal IgA antibody against Helicobacter pylori in chronic gastritis and intestinal metaplasia detected by the Tes-Tape method in resection specimens after gastrectomy for gastric cancer

BACKGROUND

Subjects with atrophic body gastritis have a high prevalence of Helicobacter pylori seropositivity and a low prevalence of H. pylori infection. Disappearance of the organism appears to correlate with the development of intestinal metaplasia. To investigate this point, intestinal metaplasia was biochemically subclassified into complete and incomplete types by the Tes-Tape method, and tissue IgA and IgG antibodies against H. pylori were measured by enzyme-linked immunosorbent assay (ELISA).

METHODS

Twenty-five stomachs resected for gastric cancer were examined using the Tes-Tape method. Serum H. pylori IgA and IgG antibodies and tissue IgA and IgG antibodies against H. pylori and tissue secretory IgA (sc-IgA) were examined in areas of intestinal metaplasia, nonmetaplastic gastric mucosa, and gastric carcinoma by ELISA:

RESULTS

Tissue H. pylori IgA antibody was positive in 6 of 19 (32%) specimens taken from complete and 2 of 7 (29%) incomplete types of intestinal metaplasia and was positive in 6 of 14 (43%) nonmetaplastic gastric mucosa from the antrum and 14 of 23 (61%) from the body. Duodenal mucosa and cancer tissue were positive for tissue IgA antibody in 1 of 6 (17%) and 0 of 17 (0%), respectively. Tissue H. pylori IgG antibody was negative in all the tissues examined. sc-IgA in the areas of intestinal metaplasia was 120 +/- 65 (mean +/- standard error; ng/mg wet weight) and in the nonmetaplastic gastric mucosa was 113 +/- 72, showing no difference. Positivity and negativity of serum IgA and IgG antibodies against H. pylori coincided with presence or absence of tissue IgA antibody in nonmetaplastic gastric mucosa in 15 of 19 (79%) and 16 of 19 (84%) patients examined, respectively.

CONCLUSION

Positivity rates of tissue IgA antibody against H. pylori were lower in the mucosa of intestinal metaplasia than in nonmetaplastic gastric mucosa and were negative in carcinoma. No significant difference in levels of sc-IgA between intestinal metaplasia and non-metaplastic gastric mucosa was found.

Sequence and expression of a candidate for the human Secretor blood group alpha(1,2)fucosyltransferase gene (FUT2). Homozygosity for an enzyme-inactivating nonsense mutation commonly correlates with the non-secretor phenotype

Synthesis of soluble A, B, H, and Lewis b blood group antigens in humans is determined by the Secretor (Se) (FUT2) blood group locus. Genetic, biochemical, and molecular analyses indicate that this locus corresponds to an alpha(1,2)fucosyltransferase gene distinct from the genetically-linked H blood group alpha(1,2)fucosyltransferase locus. The accompanying paper (Rouquier, S., Lowe, J. B., Kelly, R. J., Fertitta, A. L., Lennon, G. G., and Giorgi, D. (1995) J. Biol. Chem. 270, 4632-4639) describes the molecular cloning and mapping of two human DNA segments that are physically linked to, and cross-hybridize with, the H locus. We present here an analysis of these two new DNA segments. One of these, termed Sec1, is a pseudogene, because translational frameshifts and termination codons interrupt potential open reading frames that would otherwise share primary sequence similarity with the H alpha(1,2)fucosyltransferase. The other DNA segment, termed Sec2, predicts a 332-amino acid-long polypeptide, and a longer isoform, that share 68% sequence identity with the COOH-terminal 292 residues of the human H blood group alpha(1,2)fucosyltransferase. Sec2 encodes an alpha(1,2)fucosyltransferase with catalytic properties that mirror those ascribed to the Secretor locus-encoded alpha(1,2)fucosyltransferase. Approximately 20% of randomly-selected individuals were found to be apparently homozygous for an enzyme-inactivating nonsense allele (Trp143-->ter) at this locus, in correspondence to the frequency of the non-secretor phenotype in most human populations. Furthermore, each of six unrelated non-secretor individuals are also apparently homozygous for this null allele. These results indicate that Sec2 corresponds to the human Secretor blood group locus (FUT2) and indicate that homozygosity for a common nonsense allele is responsible for the nonsecretor phenotype in many non-secretor individuals.

Improvement of gastric inflammation and resolution of epithelial damage one year after eradication of Helicobacter pylori

AIMS

To investigate the effect of eradication of Helicobacter pylori infection on gastric epithelial damage and gastritis, scored according to the Sydney system.

METHODS

Gastritis scores and epithelial damage were assessed in gastric biopsy specimens before, and five weeks and one year after anti-H pylori therapy in 66 patients with H pylori related gastritis.

RESULTS

The mean initial levels of activity, inflammation, atrophy, intestinal metaplasia, and H pylori scores were higher in the antrum than in the corpus or fundus. Eradication of H pylori resulted in an improvement in the mean inflammatory score in antral biopsy specimens from 2.23 before treatment to 1.32 and 1.06, respectively, five weeks and one year after treatment. Corresponding values for fundic biopsy specimens were 1.30, 0.36 and 0.35. Activity scores improved from 1.41 before treatment to 0.13 and zero, respectively, five weeks and one year after treatment in antral biopsy specimens and from 0.60 before treatment to zero in fundic biopsy specimens. Before treatment, epithelial damage was present in 51% of biopsy specimens taken from the antrum and 23% of those from the corpus. Five weeks after eradication of H pylori none of the biopsy specimens revealed evidence of epithelial damage.

CONCLUSION

Eradication of H pylori is followed by a rapid, significant improvement in the gastritis score and resolution of epithelial damage in antral and fundic mucosa.