Molecular analysis of B-cell clonality in Helicobacter pylori gastritis

T Cell-Dependent Maturation of Pathogen-Specific Igs in the Antrum of Chronically Helicobacter pylori-Infected Patients

Mucosal plasma cells (PC) and Ig production are essential to fend pathogens and to maintain mucosal homeostasis. In human Helicobacter pylori infection, mucosal PC express inducible NO synthase (iNOS), which positively correlates with clearance of experimental human infection. To characterize Ig genes and specificities of antral mucosal iNOS⁺ and iNOS^- PC in H. pylori infection, we sequenced rearranged Ig genes from single cell-sorted PC from biopsy specimens of chronically infected patients and analyzed them with respect to their molecular features. The binding specificity of individual PC's Ig was determined following recombinant expression. We identified high rates of somatic hypermutations, especially targeting RGYW/WRCY hotspot motifs in the individual Ig genes, indicating T cell-dependent maturation. For seven of 14 recombinantly expressed Ig, Ag specificity could be determined. Two clones reacted to H. pylori proteins, and five were found to be polyreactive against LPSs, dsDNA, and ssDNA. All specific Ig originated from iNOS⁺ PC. H. pylori-specific Ig are encoded by V and J family genes previously shown to be also used in rearranged Ig loci of MALT B cell lymphomas. In summary, mucosal iNOS⁺ PC producing H. pylori-specific Ig accumulate in infection and appear to be a product of T cell-dependent B cell maturation. Moreover, the Ig's molecular features partly resembled that of MALT B cell lymphoma Ig genes, suggestive of a mechanism in which a progressive molecular evolution of pathogen-specific B cells to MALT B cell lymphoma occurs.

Enzyme-labeled Antigen Method: Development and Application of the Novel Approach for Identifying Plasma Cells Locally Producing Disease-specific Antibodies in Inflammatory Lesions

In chronic inflammatory lesions of autoimmune and infectious diseases, plasma cells are frequently observed. Antigens recognized by antibodies produced by the plasma cells mostly remain unclear. A new technique identifying these corresponding antigens may give us a breakthrough for understanding the disease from a pathophysiological viewpoint, simply because the immunocytes are seen within the lesion. We have developed an enzyme-labeled antigen method for microscopic identification of the antigen recognized by specific antibodies locally produced in plasma cells in inflammatory lesions. Firstly, target biotinylated antigens were constructed by the wheat germ cell-free protein synthesis system or through chemical biotinylation. Next, proteins reactive to antibodies in tissue extracts were screened and antibody titers were evaluated by the AlphaScreen method. Finally, with the enzyme-labeled antigen method using the biotinylated antigens as probes, plasma cells producing specific antibodies were microscopically localized in fixed frozen sections. Our novel approach visualized tissue plasma cells that produced 1) autoantibodies in rheumatoid arthritis, 2) antibodies against major antigens of Porphyromonas gingivalis in periodontitis or radicular cyst, and 3) antibodies against a carbohydrate antigen, Strep A, of Streptococcus pyogenes in recurrent tonsillitis. Evaluation of local specific antibody responses expectedly contributes to clarifying previously unknown processes in inflammatory disorders.

Russell body gastritis/duodenitis: a case series and description of immunoglobulin light chain restriction

Russell body esophago-gastro-duodenitis is an unusual form of chronic inflammation, with only 22 cases being reported in PubMed. However, the prevalence and clinical significance remain unknown. This report describes the clinico-pathological characteristics of nine cases of Russell body gastritis (RBG) and one case of Russell body duodentitis (RBD), with nonspecific endoscopic appearance. The Mott cells (plasma cells with Russell bodies) showed κ light chain restriction in eight gastritis cases and λ light chain restriction in the duodentitis case, and there were no histological features that suggested lymphoma. Thus, a diagnosis of monoclonal RBG/RBD was made. Helicobacter pylori infection was found in 55.6% of RBG cases and in the RBD case. And, the clinical follow-up evaluations were uneventful. This report is the first study to describe this benign disease entity with monoclonality on a large-scale basis. In addition, the monoclonality of Mott cells cannot be used as evidence of an existing neoplastic lesion, and taken together, these findings may indicate a reactive process.

Immunoglobulin gene repertoire diversification and selection in the stomach - from gastritis to gastric lymphomas

Chronic gastritis is characterized by gastric mucosal inflammation due to autoimmune responses or infection, frequently with Helicobacter pylori. Gastritis with H. pylori background can cause gastric mucosa-associated lymphoid tissue lymphoma (MALT-L), which sometimes further transforms into diffuse large B-cell lymphoma (DLBCL). However, gastric DLBCL can also be initiated de novo. The mechanisms underlying transformation into DLBCL are not completely understood. We analyzed immunoglobulin repertoires and clonal trees to investigate whether and how immunoglobulin gene repertoires, clonal diversification, and selection in gastritis, gastric MALT-L, and DLBCL differ from each other and from normal responses. The two gastritis types (positive or negative for H. pylori) had similarly diverse repertoires. MALT-L dominant clones (defined as the largest clones in each sample) presented higher diversification and longer mutational histories compared with all other conditions. DLBCL dominant clones displayed lower clonal diversification, suggesting the transforming events are triggered by similar responses in different patients. These results are surprising, as we expected to find similarities between the dominant clones of gastritis and MALT-L and between those of MALT-L and DLBCL.

Screening for gastric premalignant lesions with narrow band imaging, white light and updated Sydney protocol or both?

BACKGROUND

Narrow band imaging (NBI) can accurately discriminate gastritis but premalignant lesions (PMLs) are difficult to detect.

AIMS

The purpose of this study was to compare white light endoscopy (WLE) and histopathologic findings using the updated Sydney protocol (USP) with NBI and targeted biopsies (TB).

METHODS

One hundred nineteen symptomatic patients referred for upper GI endoscopy were included in this prospective open study. All patients were assessed for gastritis and PMLs using WLE and NBI by two endoscopists selected in a random manner. Biopsies were taken according to USP and targeted from any area suspicious for PML. Imaging and histological findings between protocols were compared.

RESULTS

In total 45 patients (38 %) had atrophy of whom 39 (32.7 %) were detected with WLE-USP and 28 (23.5 %) with NBI-TB (p = 0.03), 25 (21 %) had intestinal metaplasia (IM) of whom 19 (16 %) were detected with WLE-USP and 18 (15.1 %) with NBI-TB (p = 0.7) and 14 (12 %) had dysplasia of whom 12 (10 %) were detected with WLE-USP and 7 (7 %) with NBI-TB (p = 0.5), and 1 (0.8 %) case of gastric cancer only detected with WLE-USP. Accuracies for atrophy and IM were 93 and 90 % for the WLE-USP and 80 and 82 % for NBI-TB. The NBI-TB detected six cases of atrophy (13 %), 5 (20 %) of IM, and 2 (14 %) of dysplasia missed by WLE-USP as agreement was moderate. Accuracies of the NBI patterns for body and antral gastritis were 80 and 84 %.

CONCLUSIONS

In a non high-risk population NBI-TB has less accuracy in detecting premalignant lesions compared to WLE-USP. However, it may be used as an important and easy-to-use complementary method which increases overall detectability for gastric premalignant lesions.

Molecular Aspects of H. pylori-Related MALT Lymphoma

Helicobacter pylori-related extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue is a paradigm for malignancy arising in an inflammatory background. While the diagnosis of H. pylori gastritis is often straightforward, distinction between severe gastritis and early lymphoma can be difficult and requires careful assessment of clinical findings in addition to histological features and immunohistochemical results. A number of cytogenetic abnormalities have been discovered in H. pylori-related lymphomas and several have clinical importance, related to the responsiveness of lymphoma to H. pylori eradication therapy, but routine molecular studies are not widely utilized. While molecular methods may be used in equivocal cases, a trial of conservative therapy is warranted given the propensity for these lymphomas to regress with eradication of the organism. Once therapy is initiated, care must be taken to avoid a premature assignment of disease refractoriness because complete response can take several months to more than a year. Cases truly refractory to H. pylori eradication therapy may be treated with adjuvant chemoradiation with a high response rate.

Helicobacter pylori infection and chronic immune thrombocytopenic purpura: long-term results of bacterium eradication and association with bacterium virulence profiles

Eradication of Helicobacter pylori may lead to improvement of chronic immune thrombocytopenic purpura (ITP), although its efficacy over time is uncertain. We report the results of H pylori screening and eradication in 75 consecutive adult patients with ITP. We also used molecular methods to investigate lymphocyte clonality and H pylori genotypes in the gastric biopsies from 10 H pylori-positive patients with ITP and 19 H pylori-positive patients without ITP with chronic gastritis. Active H pylori infection was documented in 38 (51%) patients and successfully eradicated in 34 (89%) patients. After a median follow-up of 60 months, a persistent platelet response in 23 (68%) of patients with eradicated infection was observed; 1 relapse occurred. No differences in mucosal B- or T-cell clonalities were observed between patients with ITP and control participants. Of note, the frequency of the H pylori cagA gene (P = .02) and the frequency of concomitant H pylori cagA, vacAs1, and iceA genes (triple-positive strains; P = .015) resulted statistically higher in patients with ITP than in control participants. All asymptomatic H pylori-positive patients with ITP were suffering from chronic gastritis. Our data suggest a sustained platelet recovery in a proportion of patients with ITP by H pylori eradication alone. Overrepresentation of specific H pylori genotypes in ITP suggests a possible role for bacterium-related factors in the disease pathogenesis.