Anti-CD40L therapy prevents the formation of precursor lesions to gastric B-cell MALT lymphoma in a mouse model

Mucosa-associated lymphoid tissue (MALT) lymphoma is a B-cell tumour that develops over many decades in the stomachs of individuals with chronic Helicobacter pylori infection. We developed a new mouse model of human gastric MALT lymphoma in which mice with a myeloid-specific deletion of the innate immune molecule, Nlrc5, develop precursor B-cell lesions to MALT lymphoma at only 3 months post-Helicobacter infection versus 9-24 months in existing models. The gastric B-cell lesions in the Nlrc5 knockout mice had the histopathological features of the human disease, notably lymphoepithelial-like lesions, centrocyte-like cells, and were infiltrated by dendritic cells (DCs), macrophages, and T-cells (CD4+ , CD8+ and Foxp3+ ). Mouse and human gastric tissues contained immune cells expressing immune checkpoint receptor programmed death 1 (PD-1) and its ligand PD-L1, indicating an immunosuppressive tissue microenvironment. We next determined whether CD40L, overexpressed in a range of B-cell malignancies, may be a potential drug target for the treatment of gastric MALT lymphoma. Importantly, we showed that the administration of anti-CD40L antibody either coincident with or after establishment of Helicobacter infection prevented gastric B-cell lesions in mice, when compared with the control antibody treatment. Mice administered the CD40L antibody also had significantly reduced numbers of gastric DCs, CD8+ and Foxp3+ T-cells, as well as decreased gastric expression of B-cell lymphoma genes. These findings validate the potential of CD40L as a therapeutic target in the treatment of human gastric B-cell MALT lymphoma. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Helicobacter pylori as a class I carcinogen: physiopathology and management strategies

The gram-negative bacterium Helicobacter pylori is known as a persistent colonizer of the human stomach, and probably less known is that it is also involved in extraintestinal diseases. Public awareness of its contribution in the development of gastric cancer is less than 15 years old. The efficacy of the current therapies based on antibiotics against H. pylori has been limited by difficulties such as antibiotic resistance and recurrence. As a consequence, the development of promising vaccines was prompted as the best preventive measure. Unfortunately, so far vaccines failed the transition from animal models to human trials. This keynote presentation is to provide a bird's eye view of H. pylori-related gastric diseases, including gastric cancer, with a synthesis of the molecular mechanisms involved, and an exhaustive presentation and discussion of the current therapeutic guidelines and future strategies for prevention or therapy.

Helicobacter pylori eradication for low-grade gastric mucosa-associated lymphoid tissue lymphoma is more successful in inducing remission in distal compared to proximal disease

A series of studies has shown that Helicobacter pylori eradication induces remission in most patients with low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma. However, there have been few reports about the effect of bacterial treatment on the gastric MALT lymphoma in Korea, a well-known H. pylori endemic area. A total of 111 H. pylori-infected patients were prospectively enrolled in Seoul National University Hospital and 99 among them were completely followed up according to our protocol. After H. pylori eradication, tumoural response was evaluated by endoscopy and histopathology every 2–3 months till complete remission (CR) and every 6 months after achieving CR. Median follow-up period was 41 months (range, 11–125 months). Helicobacter pylori was successfully eradicated in all 99 patients and CR was obtained in 84 (84.8%) of 99 patients. The median time to reach CR was 3 months and 94% of CR is in continuous complete remission. Five patients with CR relapsed after 10–22 months without the evidence of H. pylori reinfection. Cumulative recurrence rate was 2.3, 7.7 and 9.3% at 1, 2 and 3 years, respectively. Tumours were mainly located in distal stomach (67.7%) and tumours in distal stomach were associated with more favourable response than those in proximal stomach (P=0.001). Majority of patients with low-grade gastric MALT lymphoma treated by exclusive H. pylori eradication have a favourable long-term outcome, offering a real chance of cure. Tumour location could be a predictive factor for remission following H. pylori eradication.

Rituximab in patients with mucosal-associated lymphoid tissue-type lymphoma of the ocular adnexa

Eight patients with ocular adnexal mucosal-associated lymphpid tissue (MALT) lymphoma were treated with rituximab, at diagnosis (n=5) or relapse (n=3). All untreated patients achieved lymphoma regression, while relapsing patients had no benefit. Four responding patients experienced early relapse. The median time to progression was 5 months. The efficacy of rituximab in ocular adnexal lymphoma is lower than that reported for gastric MALT lymphomas.

Helicobacter pylori and Gastric Malignancy

Last year there were a few important clinical data on long-term prognosis of mucosa-associated lymphoid tissue (MALT) lymphoma after eradication of Helicobacter pylori. Similarly, there were clinical data to support the role of eradication of H. pylori in the primary prevention of gastric cancer. We understand more about the host susceptibility as well as the pathogenetic mechanisms of the bacteria in the gastric mucosa. This article summarizes the important breakthroughs in H. pylori and gastric malignancies last year.

[Helicobacter pylori: reasons for eradication]

Helicobacter pylori infection has been recognized as the most important pathogenetic principal of peptic ulcer disease, atrophic gastritis, gastric adenocarcinoma and MALT lymphoma. At the moment efforts are made to clarify it's role in functional dyspepsia, and gastro-esophageal reflux disease. The complex interactions between H. pylori infection and NSAIDs is another field of ongoing research. Diagnosis and eradication therapy are standardized. Established indications are peptic ulcer disease, low-grade gastric MALT lymphoma, early gastric cancer treated by mucosal resection and partial gastrectomy for gastric cancer. Atrophic gastritis, known to be a precancerous lesion, as well as first degree relatives of patients with gastric cancer is another widely accepted indication for eradication therapy. The recommended eradication regimens combine a proton pump inhibitor with clarithromycin and either amoxicillin or metronidazole--for a week.

Immunisation against Helicobacter felis infection protects against the development of gastric MALT Lymphoma

The formation of mucosa-associated lymphoid tissue (MALT) in response to Helicobacter pylori infection is closely associated with the development of primary gastric MALT lymphoma.

AIM

To examine whether immunisation against Helicobacter felis can protect against development of MALT lymphoma.

RESULTS

The majority of control infected mice demonstrated MALT formation (13/15) and five developed lymphoma. Fifteen immunised mice were protected against bacterial challenge, of which only five had evidence of MALT formation and none developed lymphoma. Interestingly, of the four mice in which immunisation failed, all developed MALT and two of these had lymphoma.

CONCLUSION

Effective immunisation against Helicobacter infection can protect against gastric MALT lymphoma. To our knowledge this is the first demonstration of vaccination protecting against a bacteria-induced malignancy.

[Guidelines for the diagnosis and treatment of H. pylori infection]

In accordance with our current understanding, infection with the pathogen Helicobacter pylori is an important, but readily diagnosable and treatable cause of various gastroduodenal diseases. A lasting cure is achieved when the bacterium is eradicated with the aid of an established therapeutic regimen. Furthermore, eradication is a rational preventive measure even in asymptomatic patients, since current clinical data show that it offers protection, in particular to high-risk groups, from gastric carcinoma, but also from other complications (e.g. peptic ulcer). The upgraded European Guidelines on the diagnosis and treatment of H. pylori infection put out by the European Helicobacter Pylori Study Group (EHPSG) in Maastricht take account of the present state of our knowledge of the significance of H. pylori eradication.

[Could Helicobacter pylori treatment reduce stomach cancer risk?]

Despite its dramatic decline in incidence in developed countries, gastric cancer is a major public health issue in the world. Accumulating evidence for considering H. pylori as a causal factor for gastric cancer comes from recent epidemiologic studies, the advent of an animal model of gastric cancer and from new insights into the biological mechanisms for gastric carcinogenesis. The stomach cancer risk for people infected with H. pylori is rather low, inferior to 1%. It depends on genotypic polymorphisms of both the bacterium and the host. Environmental risk factors such as smoking habits, salt intake, and the amount of antioxidants in diet may interfere with H. pylori and modify the cancer risk. There is no definite clinical evidence of the benefit of eradication on cancer risk in humans due to the lack of randomized controlled studies in large populations. The occurrence of gastric adenocarcinomas in patients after complete remission of gastric MALT lymphoma induced by H. pylori eradication suggests also the limits of the preventive strategy against gastric cancer. Furthermore, the effectiveness of eradication to reverse precancerous gastric lesions such as severe atrophy and intestinal metaplasia is questionable. For many reasons discussed in our review, population-based screening and routine eradication of H. pylori infection seem to be an unrealistic goal and cannot be recommended in France. By waiting for effective anti-H. pylori vaccine, public health measures such as dietary modification should be promoted to further decrease the gastric cancer incidence. On the individual basis the specialist has a role in the diagnosis of gastric precancerous lesions by endoscopy and also in the prevention of gastric cancer by selecting indications for H. pylori therapy.

Gastric neoplasia

This review summarizes the significant recent advances in our understanding of the clinical, epidemiologic, and pathologic aspects of gastric adenocarcinoma, gastrointestinal stromal tumors (GISTs), and mucosa-associated lymphoid tissue (MALT) lymphoma. Most of the advances in distal gastric adenocarcinoma are in its etiology and pathogenesis. The modulation of the inflammatory response to Helicobacter pylori organisms has been determined to be at the center of the precancerous process. These advances in the understanding of the pathogenesis of H. pylori-related carcinogenesis are relevant to the design of prevention strategies in high-risk populations. New markers of GISTs have focused on the cell of origin and have made possible the development and monitoring of new drugs that are effective even in metastatic tumors. MALT lymphomas have been causally associated with H. pylori infection. Molecular markers are useful to distinguish tumors that respond to H. pylori eradication from those requiring classic chemotherapy.

Gastric MALT-lymphoma, gastrin and cyclooxygenases

Malt-lymphoma, gastrin and COX-2 interaction. Low grade, mucosal associated lymphoid tissue (MALT)-lymphoma is an unique among gastric malignancies where causal involvement of Helicobacter pylori (H. pylori) infection has been proposed based on complete regression of the tumor following the eradication therapy. In this report ten primary, low-grade MALT-lymphomas have been examined before and 6 months after one week of successful eradication therapy (clarithromycin + amoxicillin + omeprazole). Gastric biopsy samples from tumor and intact antrum and corpus mucosa were obtained during endoscopy before and after eradication for assessment of expression of gastrin and gastrin receptor (CCKB-R) as well as cyclooxygenase (COX)-1 and COX-2 using RT-PCR. The gastric lumen and serum gastrin and mucosal and tumor tissue PGE2 biosynthesis were determined by RIA before and after H. pylori eradication. Eradication of H. pylori resulted in complete endoscopic and histological remission of MALT-lymphoma in 9 out of 10 patients as assessed 6 months after this eradication. Before eradication, the mRNA expression for gastrin and CCKB-R as well as mRNA expression for COX-1 and COX-2 were observed in tumor tissue and infected mucosa, while corpus mucosa expressed only CCKB-R and antrum mucosa only gastrin. Six months upon the eradication when MALT-lymphoma completely regressed both endoscopically and histologically in 9 of 10 tested subjects, the expression of gastrin and COX-2 disappeared from the former area of MALT-lymphoma tumor. Gastrin mRNA remained detectable only in antrum mucosa, CCKB-R mRNA in corpus mucosa and COX-1 mRNA both in antrum and corpus mucosa. Gastric luminal and serum gastrin levels and gastric mucosa and tumor PGE2, which were greatly elevated before eradication, became normalized after this procedure. This study demonstrates that low-grade MALT-lymphoma is linked to H. pylori infection which may promote the expression and excessive release of gastrin and COX-2 expression that could be involved in the pathogenesis of MALT-lymphoma.

[Helicobacter pylori eradication. Therapeutic evolution, value of complementary studies]

INDICATIONS

Eradication of Helicobacter pylori is needed for patients with a gastroduodenal ulcer associated with H. pylori gastritis. Eradication modifies the natural history of the disease and greatly reduces the risk of recurrence. Eradication is also indicated for patients with MALT lymphoma with a low degree of malignancy. Systematic eradication of H. pylori would not be necessary for patients with dyspepsia associated with H. pylori gastritis since a beneficial effect is achieved in only 5% of the treated patients. Systematic eradication in order to reduce the incidence of gastric adenocarcinoma is not recommended.

DIAGNOSIS

Direct tests (urease, pathology) provide the diagnosis of H. pylori gastritis. Indirect tests (13C-labeled urea respiratory test) can be most useful to determine the efficacy of eradication treatments.

THERAPY

A tri-therapy regimen given for 7 days combining a double-dosed proton pump inhibitor, amoxicillin (2 g/d), and clarithromycin (0.5 g b.i.d) is used to eradicate H. pylori. With this regimen, the mean rate of eradication achieved in France is 67%. The principal causes of failure are poor compliance and bacterial resistance to clarithromycin. Metronidazole (1 g/d) can be used for patients allergic to penicillin. A second cycle can be prescribed in case of failure, substituting metronidazole for clarithromycin.

FOLLOW-UP

Eradication treatment is prescribed for patients with an ulcer after confirmation of infection by one or two direct tests. Treatment efficacy can be assessed by the respiratory test for patients with a duodenal ulcer but is not systematically needed. Biopsy of a gastric ulcer can also provide an assessment of treatment efficacy. For patients with a non-complicated duodenal ulcer, antisecretion treatment is not required in addition to eradication treatment.

Review article: would eradication of Helicobacter pylori infection reduce the risk of gastric cancer?

This article reviews the data on the epidemiology of gastric cancer, to determine if treatment of an asymptomatic individual can be justified. It reviews retrospective and prospective case-control studies of gastric cancer in Italy and other countries. Mucosa-associated lymphoid tissue lymphoma is associated with Helicobacter pylori infection. The risk of noncardia gastric cancer is higher (4-fold or greater) in those with H. pylori infection. Although no studies have shown prevention following treatment, eradication of asymptomatic H. pylori infection in an individual in the age group 40 or lower may be expected to reduce the risk of gastric cancer.

Gastrointestinal lymphoma: prevention and treatment of early lesions

Gastrointestinal lymphomas comprise a group of distinct clinicopathological entities. Differences in lifestyle and environmental factors between countries could account for the variety in the distribution of the main subtypes: low-grade B-cell lymphomas of the mucosa-associated lymphoid tissue type, alpha-chain disease and enteropathy (coeliac disease)-associated T-cell lymphoma (EATL). The possibility of preventing these lymphomas implies a knowledge of their natural history together with an identification of potential predisposing factors. The development of the lymphoid hyperplasia and subsequently low-grade lymphoma with the possibility of high-grade transformation is a multifactorial process involving both antigenic and host-related factors. The pathogenic role of Helicobacter pylori and gluten has been demonstrated in gastric lymphoma and enteropathy-associated T-cell lymphoma respectively, while environmental factors, especially non-specific bacterial ones, may play a major role in the pathogenesis of alpha-chain disease. The most difficult task in preventing these lymphomas is the recognition of early lesions likely to regress after the removal of the exogenous stimulus.

[Stomach lymphomas: minimum diagnostic requirements for gastrointestinal histopathological diagnosis]

Gastric lymphomas have been the subject of intensive studies in the last years and important progress has been made regarding their etiopathogenesis and therapy. Diagnosis of gastric lymphoma is usually made on bioptic material taken at endoscopy. Histopathologic diagnosis is frequently difficult. This paper summarizes the main diagnostic criteria of this setting. It analyses the morphological, immunohistochemical and molecular features to be considered for the differential diagnosis between: reactive process vs low grade B-cell gastric MALT lymphoma, B-cell MALT lymphoma vs other low grade lymphomas involving the stomach and low grade vs high grade gastric lymphoma. The histopathological aspects of gastric biopsies after antibiotic treatment for Helicobacter pylori eradication and the role of molecular analysis in the follow-up of these patients are also considered.

[The association between Helicobacter pylori and gastric neoplasia. Epidemiologic evidence]

Helicobacter pylori (HP) causes chronic gastritis and, together with non-steroidal anti-inflammatory drugs, is considered the most frequent etiologic agent of peptic ulcer. Since there are numerous epidemiologic and pathogenesis studies that demonstrate an association between infection by HP and gastric neoplasias, the World Health Organization declared, in 1994, HP infection a Group 1 carcinogen (a definitive cause of human neoplasias, similar to tobacco). This article reviews the epidemiological evidence supporting the association between HP infection and two gastric neoplasias: adenocarcinoma and B cell lymphoma associated to mucosas (MALT). This article also presents preliminary results of a project performed in the mountainous region of Chiapas, Mexico, in which the decrease of precancerous gastric lesions were studied one year after treatment for HP infection.

[Relevance of Helicobacter pylori infection in the development of gastric tumors]

Helicobacter pylori plays an important role in the pathogenesis of peptic ulcer disease. Besides, epidemiological studies indicate that helicobacter may be involved in the development of gastric cancer and MALT-lymphoma by inducing gastritis and accumulation of lymph follicles in the gastric mucosa. The carcinogenic effect of helicobacter pylori can be explained by various pathogenetic factors which are produced by the bacterium itself. Furthermore, influences of helicobacter pylori on the vitamin C content of gastric mucosa might play a role. Currently, Hp-eradication therapies for the treatment of gastric MALT lymphomas are already under investigation in controlled studies. Concerning gastric cancer prevention, however, the available data are not sufficient to warrant a general recommendation for eradication-therapies of all Hp-infected persons. However, further studies must show whether Hp-eradication of high-risk subjects, i.e. members of gastric cancer families, young patients with chronic-active gastritis or with chronic-atrophic gastritis and intestinal metaplasia, are effective in reducing gastric cancer risk.

Gastric lymphoma of mucosa-associated lymphoid tissue and Helicobacter pylori

Although the majority of primary gastric lymphomas are of high-grade non-Hodgkin's type, a significant number are low-grade B cell lymphomas. The recognition that the majority of the latter have characteristic clinicopathological features that are different from those of their nodal counterparts has led to the suggestion that these lymphomas arise specifically from within organized extranodal lymphoid tissue; this tissue resembles that seen constitutively in the intestine (mostly located in the terminal ileum as Peyer's patches) and is termed mucosa-associated lymphoid tissue (MALT). The paradox of this proposal is that there is no MALT in the gastric mucosa in normal individuals from which a primary lymphoma can arise. However, it has been shown that organized lymphoid tissue with all the features of MALT can be acquired in the gastric mucosa, and this is seen most frequently, but not exclusively, in association with infection by Helicobacter pylori (H. pylori). Subsequent studies have confirmed a close association between H. pylori infection and gastric MALT lymphoma with the infection preceding the development of the lymphoma. In vitro studies have demonstrated that there is an immunologically based drive to tumor cell proliferation in low-grade gastric MALT lymphomas associated with the presence of H. pylori. Clinical studies have shown that, at least in early lesions, eradication of the organism can result in tumor regression in 60 to 92% of cases.

Prevention and treatment of low-grade B-cell primary gastric lymphoma by anti-H. pylori therapy

Mucosa-associated lymphoid tissue (MALT) showing a follicular structure can develop in the gastric mucosa as a response to Helicobacter pylori infection. We emphasize the importance of anti-H. pylori antibiotic therapy in the elimination of acquired MALT. Of the 200 patients studied, acquired MALT was found in 70 of the 151 H. pylori-positive patients, whereas it was present in only five of the 49 H. pylori-negative patients. Thirty-eight H. pylori-positive and MALT-positive patients were treated with antibiotic therapy and reevaluated after 6 months: 21 patients were H. pylori negative/MALT negative, 12 were H. pylori positive/MALT positive, four were H. pylori negative/MALT positive, one was H. pylori positive/MALT negative. In the control group (n = 20), H. pylori and acquired MALT were still present at follow-up. One patient with histological and immunohistochemical evidence of low-grade B-cell gastric MALT lymphoma underwent antibiotic treatment and was reexamined after 8, 12, and 24 weeks: histological examination of biopsy samples showed regression of the MALT lymphoma in tandem with the disappearance of H. pylori colonization. Our data confirm the correlation between H. pylori infection and acquired MALT, as documented by the ability of antibiotic therapy to induce the disappearance of acquired MALT and regression of MALT lymphoma. Considering the potential evolution of MALT into low-grade B-cell MALT lymphoma, H. pylori eradication should play a role in the prevention of this tumor.

[MALT lymphoma, stomach carcinoma--role of Helicobacter pylori. Are chances for prevention on the horizon?]

The pathogenesis of gastric carcinoma developing after infection with Helicobacter pylori now seems to be clear. The release of urease, alcohol dehydrogenase, enzymes and cytotoxin on the one hand, and chemotactic factors, PAF and heat-shock proteins on the other trigger chronic inflammation and epithelial metaplasia and dysplasia in the stomach. Under the influence of additional carcinogens, the epithelial changes progress to severe dysplasia and finally carcinoma. As a result of chronic inflammation, MALT lymphomas can also be induced. These can be made to regress by eradicating Hp. The possibility of being able to prevent up to 80% of the carcinomas of the stomach by eradicating Hp holds out good prospects, over the long-term, for the prevention of these tumors. Accurate identification of the patient groups carrying a high risk is now necessary.