Immunoglobulin G1 antibody response to Helicobacter pylori heat shock protein 60 is closely associated with low-grade gastric mucosa-associated lymphoid tissue lymphoma

Helicobacter pylori Virulence Factors-Mechanisms of Bacterial Pathogenicity in the Gastric Microenvironment

Gastric cancer constitutes one of the most prevalent malignancies in both sexes; it is currently the fourth major cause of cancer-related deaths worldwide. The pathogenesis of gastric cancer is associated with the interaction between genetic and environmental factors, among which infection by Helicobacter pylori (H. pylori) is of major importance. The invasion, survival, colonization, and stimulation of further inflammation within the gastric mucosa are possible due to several evasive mechanisms induced by the virulence factors that are expressed by the bacterium. The knowledge concerning the mechanisms of H. pylori pathogenicity is crucial to ameliorate eradication strategies preventing the possible induction of carcinogenesis. This review highlights the current state of knowledge and the most recent findings regarding H. pylori virulence factors and their relationship with gastric premalignant lesions and further carcinogenesis.

Helicobacter pylori-an infectious risk factor for atherosclerosis?

Accumulating evidence implicates Helicobacter pylori (H. pylori) infection in the pathogenesis of certain diseases localized outside the stomach, particularly those characterized by persistent and low-grade systematic inflammation. Recently, the role of H. pylori infection in the development of atherosclerosis and its clinical complications has received attention. Atherosclerosis is a high-cost disease, and acute events resulting from this condition rank first among morbidity and mortality statistics in most industrialized countries. Atherosclerosis is a multifactorial disorder, and traditional risk factors explain only 50% of its etiology. Therefore, identifying new risk factors for atherosclerosis is necessary. Serological studies indicate that chronic H. pylori infection, especially that with more virulent strains, may predispose patients to the onset of atherosclerosis and related adverse clinical events, and PCR studies have detected H. pylori DNA in atherosclerotic plaques, although this finding remains controversial. If this association were to be confirmed, its importance to public health would be substantial, as the eradication of H. pylori is more straightforward and less costly than the long-term treatment of other risk factors. This review investigates the potential relationship between H. pylori infection and atherosclerosis from both epidemiological and pathogenic perspectives and characterizes the potential mechanisms underlying this correlation.

Marginal zone lymphomas and infectious agents

A link with infectious agents, bacteria and viruses in particular, has been reported for many lymphoma entities. Marginal zone lymphomas (extranodal, nodal and splenic forms) are frequently associated with chronic infections, with important clinical, molecular, biological, and therapeutic implications. The well-known correlation between Helicobacter pylori and gastric MALT-lymphoma, the recently reported links between Chlamydophila psittaci and ocular adnexal MALT-lymphoma and Borrelia burgdorferi and cutaneous MALT lymphoma constitute the best studied examples of lymphomagenic activity of bacteria, while the hepatitis C virus represents the most extensively investigated virus associated with marginal zone lymphomas. Biological and clinical features, therapeutic implications and future perspectives of these lymphoma-microbial associations are discussed in this review.

Immunization with the immunodominant Helicobacter suis urease subunit B induces partial protection against H. suis infection in a mouse model

Helicobacter (H.) suis is a porcine and human gastric pathogen. Previous studies in mice showed that an H. suis infection does not result in protective immunity, whereas immunization with H. suis whole-cell lysate (lysate) protects against a subsequent experimental infection. Therefore, two-dimensional gel electrophoresis of H. suis proteins was performed followed by immunoblotting with pooled sera from H. suis- infected mice or mice immunized with lysate. Weak reactivity against H. suis proteins was observed in post-infection sera. Sera from lysate-immunized mice, however, showed immunoreactivity against a total of 19 protein spots which were identified using LC-MS/MS. The H. suis urease subunit B (UreB) showed most pronounced reactivity against sera from lysate-immunized mice and was not detected with sera from infected mice. None of the pooled sera detected H. suis neutrophil-activating protein A (NapA). The protective efficacy of intranasal vaccination of BALB/c mice with H. suis UreB and NapA, both recombinantly expressed in Escherichia coli (rUreB and rNapA, respectively), was compared with that of H. suis lysate. All vaccines contained choleratoxin as adjuvant. Immunization of mice with rUreB and lysate induced a significant reduction of H. suis colonization compared to non-vaccinated H. suis-infected controls, whereas rNapA had no significant protective effect. Probably, a combination of local Th1 and Th17 responses, complemented by antibody responses play a role in the protective immunity against H. suis infections.

Chlamydia psittaci in ocular adnexa MALT lymphoma: a possible role in lymphomagenesis and a different geographical distribution

Ocular adnexa MALT-lymphomas represent approximatively 5-15% of all extranodal lymphomas. Almost 75% of OAMLs are localized in orbital fat, while 25% of cases involves conjunctive. MALT-lymphomas often recognize specific environmental factors responsible of lymphoma development and progression. In particular as Helicobacter pylori in gastric MALT lymphomas, other bacterial infections have been recognized related to MALT lymphomas in specific site. Recently Chlamydia psittaci has been identified in Ocular Adnexa MALT lymphomas, with variable frequence dependently from geographic areas. Thus bacterial infection is responsible of clonal selection on induced MALT with subsequent lymphoma development. Moreover Chlamydia psittaci could promote chromosomal aberration either through genetic instability as a consequence of induced proliferation and probably through DNA oxidative damage. The most common translocation described in MALT lymphomas affects NF-kB pathway with a substantial antiapoptotic effect. Several therapeutic approaches are now available, but the use of antibiotic-therapy in specific cases, although with conflicting results, could improve the treatment of ocular adnexa MALT lymphomas. In this review we analyse the most relevant features of Ocular adnexa MALT lymphomas, underlining specific biological characteristics mainly related to the potential role of Chlamydia psittaci in lymphomagenesis.

Antibodies against Helicobacter pylori heat shock protein 60 aggravate HSP60-mediated proinflammatory responses

Anti-Helicobacter pylori heat shock protein 60 (HpHSP60) antibodies are usually found in H. pylori-infected patients and are known to be associated with the progression of gastric diseases. However, the effects of these antibodies on the functions of HpHSP60 have not been identified. This study aims to investigate the effects of the interaction between anti-HSP60 antibodies and HpHSP60 on inflammatory responses. Anti-HpHSP60 polyclonal sera and monoclonal antibodies (mAbs) were produced to evaluate their effects on HpHSP60-induced IL-8 and TNF-α activity. The results indicated that anti-HpHSP60 polyclonal sera collected from patients infected with H. pylori or from rabbit and mice immunized with HpHSP60 could significantly enhance HpHSP60-mediated IL-8 and TNF-α secretion from monocytic THP-1 cells. Similar effects were also found with anti-HpHSP60 mAbs. Further analysis revealed that this phenomenon was only carried out by anti-HpHSP60 antibody but not by other non-specific mAbs. Moreover, the non-specific mAbs decreased the synergism of HpHSP60 and anti-HpHSP60 mAbs in proinflammatory cytokine induction. Herein, we have examined the role of anti-HpHSP60 antibody in host immune responses for the first time. This study demonstrated that H. pylori HSP60/mAbs could modulate helicobacterial pathogenesis by increasing IL-8 and TNF-α production. The pathogen-specific antibodies may execute potential immune functions rather than recognize or neutralize microbes.

Autoimmunity, infectious immunity, and atherosclerosis

INTRODUCTION

Vascular inflammation is common in certain systemic autoimmune diseases and contributes to the oxidation of low-density lipoprotein (oxLDL) and oxLDL/beta2-glycoprotein I (beta2GPI) complex formation. These complexes have been implicated as proatherogenic autoantigens that participate in the development of atherosclerotic disease.

DISCUSSION

We have demonstrated that the in vitro macrophage uptake of oxLDL/beta2GPI complexes increases in the presence of IgG anti-beta2GPI antibodies and that IgG immune complexes containing oxLDL/beta2GPI upregulate the expression of both scavenger and Fcgamma receptors to activate beta2GPI specific T cells. Some persistent infections may cause immune responses that promote atherogenesis. Cellular immunity (Th1) against Helicobacter pylori (H. pylori) derived heat shock protein 60 (Hp-HSP60) cross-reacts with endogenous HSP60 to cause cardiovascular disease likely by molecular mimicry.

CONCLUSION

Infectious cellular response may be proatherogenic,while the humoral response (antibody production) maybe protective. We review the recent progress in our understanding of autoimmunity and infectious immunity that promote atherosclerosis.

Regulation of cellular immunity prevents Helicobacter pylori-induced atherosclerosis

Helicobacter pylori (H. pylori) is a predominant pathogen that causes not only gastroduodenal diseases but also extra-alimentary tract diseases. In this study, we demonstrated that H. pylori infection promoted atherogenesis in heterozygous apoe(+/ --) ldlr(+/--) mice. The male mice were fed with high fat diet from the age of 6 weeks. At the age of 16 weeks, development of atherosclerotic lesions was observed in the H. pylori-infected mice, and it seemed to be associated with an elevation of Th1-immune response against H. pylori origin-heat shock protein 60 (Hp-HSP60) and an increment of transendothelial migration of T cells. Subcutaneous immunisation with Hp-HSP60 or H. pylori eradication with antibiotics significantly reduced the progression of atherosclerosis, accompanied by a decline of Th1 differentiation and reduction of their chemotaxis beyond the endothelium. Thus, oral infection with H. pylori accelerates atherosclerosis in mice and the active immunisation with Hp-HSP60 or the eradication of H. pylori with antibiotics can moderate/prevent cellular immunity, resulting in a reduction of atherosclerosis.

Chlamydial infection: the link with ocular adnexal lymphomas

Chlamydiae are obligate intracellular bacteria that grow in eukaryotic cells and cause a wide spectrum of diseases. They can establish persistent infections, are mitogenic in vitro, promote polyclonal cell proliferation in vivo and induce resistance to apoptosis in infected cells-properties that might contribute to tumorigenesis. In fact, Chlamydophila psittaci (Cp) has been linked to the development and maintenance of ocular adnexal marginal zone B-cell lymphoma (OAMZL). In this indolent malignancy, Cp is transported by monocytes and macrophages and causes both local and systemic infection. Cp elementary bodies are viable and infectious in the conjunctiva and peripheral blood of patients with OAMZL. Bacterial eradication with antibiotic therapy is often followed by lymphoma regression. Despite recent advances in the understanding of this bacterium-lymphoma association, several questions remain unanswered. For instance, prevalence variations among different geographical areas and related diagnostic and therapeutic implications remain a major investigational issue. We will focus on clinical and therapeutic implications of chlamydial infections in patients with lymphomas and summarize the current knowledge on the association between Cp infection and OAMZL. Available data on the epidemiology, biology and pathogenesis of this association are analyzed and new investigative and clinical approaches are discussed.

Eradication therapy for Helicobacter pylori in patients with gastric MALT lymphoma: a pooled data analysis

OBJECTIVES

Helicobacter pylori eradication is recognized as the initial therapy for gastric low-grade, B-cell, mucosa-associated lymphoid tissue (MALT) lymphoma. This study assesses (i) the H. pylori eradication rates for various first- and second-line and rescue therapies and (ii) the associated reinfection rates in patients.

METHODS

Pooled data analysis of systematic review of the literature was performed in this study.

RESULTS

Data from 34 studies with 1,271 treated patients were used. After first-line therapy, the infection was cured in 91% (95% confidence interval (CI)=89.4-92.5) of cases, the eradication rate being higher after dual therapy compared with the 7- or 14-day triple therapies (P=0.0525). After second-line therapy, the eradication rate was 80.8% (95% CI=82.7-95.1), being higher after triple rather than quadruple therapy. Further therapies (from three to five attempts) cured the infection in 75% of patients. H. pylori infection was ultimately cured in 1,250 patients, resulting in eradication rates of 98.3% (95% CI=97.6-99) and 99.8% (95% CI=99.6-100) at intention-to-treat and per-protocol analysis levels, respectively. Bacterial reinfection occurred in 18 (2.7%; 95% CI=1.4-3.9) of 676 patients who were followed-up (0.7% yearly). Overall, gastric lymphoma remission was achieved in 973 (77.8%) of 1,250 patients successfully cured of H. pylori infection.

CONCLUSIONS

This was the first comprehensive ( approximately 1,300 patients) analysis of the therapeutic management of H. pylori in gastric lymphoma patients. Data suggest that this infection is easily managed in these patients, being cured in nearly all cases.

Immune reactions against elongation factor 2 kinase: specific pathogenesis of gastric ulcer from Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection is a definite causative factor for gastric ulcers (GUs). In the present study we detected a specific antigen of gastric epithelial cells (HGC-27) using cell ELISA, which was recognized by the sera of GU patients (n = 20) but not in patients with chronic gastritis (CG; n = 20) or in healthy volunteers (HC; n = 10). This antigen was over-expressed by a stressful (heat-stressed) environment, and was identified as elongation factor 2 kinase (EF-2K) by western blotting. The GU patients' lymphocytes stimulated by H. pylori specifically disrupted heat-stressed HGC-27 cells in a cytotoxic assay. In flow cytometry, the effector cells (lymphocytes) from GU patients were significantly differentiated to T helper type 1 lymphocyte (Th1) and cytotoxic T lymphocyte (CTL) as opposed to those from CG patients. The target cells (HGC-27) expressed EF-2K and MHC-class I together with costimulatory molecules from heat stress. This antigen specific immune mechanism could have a prominent role in the pathogenesis of GU.

Infectious agents and lymphoma development: molecular and clinical aspects

This review is focused on the role of infectious agents in the development of some lymphoma entities. Associations involving bacterial infections mostly regard marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT)-type. Some paradigmatic examples of these associations include the Helicobacter pylori-related gastric MALT lymphoma and the more recently reported links between Chlamydophila psittaci and ocular adnexal MALT lymphomas and Borrelia burgdorferi and cutaneous MALT lymphomas. The well-documented association between Epstein-Barr virus infection and related lymphoproliferative disorders are analysed as an example of lymphotropic virus with tumourigenic activity. Molecular, biological and clinical features as well as therapeutic implications of these associations are analysed and future perspectives in this field are discussed.

Treatment of low-grade gastric MALT-lymphoma unresponsive to Helicobacter pylori therapy: a pooled-data analysis

The most favourable therapeutic strategy for gastric MALT-lymphoma not responding to Helicobacter pylori eradication still remains unclear, neither official guidelines nor randomised studies being available. We therefore performed a systematic review of the literature to evaluate the efficacy of different therapeutic approaches in these patients. Data regarding 315 patients were valuable, and lymphoma remission following the first therapeutic attempt was achieved in 90.1% cases. The most used therapy was radiotherapy (112 patients), followed by surgery (80 patients) and chemotherapy (68 patients), whilst a combination therapy was less frequent. Radiotherapy achieved a higher remission rate as compared to chemotherapy (97.3 vs. 85.3%; P = 0.007), being similar to surgery (97.3 vs. 92.5%; P = 0.2). No difference emerged when comparing lymphoma remission rate achieved by a single therapy with that of combined treatments (89.6 vs. 96.4%; P = 0.6). This is the first pooled-data analysis assessing the efficacy of different oncologic therapeutic approaches to treat gastric MALT-lymphoma unresponsive to H. pylori eradication. Radiotherapy seems to be the most suitable treatment in these patients.

Ocular adnexal MALT lymphoma: an intriguing model for antigen-driven lymphomagenesis and microbial-targeted therapy

Non-Hodgkin's lymphomas constitute one half of malignancies arising in the orbit and the ocular adnexae. Mucosa-associated lymphoid tissue (MALT)-type lymphoma is the most common histological category in this anatomic region. The incidence of ocular adnexal lymphoma of mucosa-associated lymphoid tissue-type (OAML) is increasing and recent studies offered new relevant insights in molecular, pathogenetic and therapeutic issues on these neoplasms. A pathogenetic model of antigen-driven lymphoproliferation similar to that reported for Helicobacter pylori-related gastric MALT lymphomas has been hypothesized for OAML. This notion is supported by the association between OAML and Chlamydophila psittaci infection, an association that is of likely pathogenetic relevance and may influence both the biological behavior and the therapeutic management of these neoplasms. However, this association displays evident geographical variability indicating that other etiopathogenic agents could be involved. These recent acquisitions coupled with the occurrence of chromosomal translocations and other genetic alterations, as well as additional risk factors like autoimmune disorders have contributed to render OAML an exciting challenge for a broad group of physicians and scientists. OAML is an indolent and rarely lethal malignancy that, in selected patients, can be managed with observation alone. Lymphomatous lesions are frequently responsible for symptoms affecting patient's quality of life, requiring, therefore, immediate treatment. Several therapeutic strategies are available, often associated with relevant side-effects. However, the therapeutic choice in OAML is not supported by consolidated evidence due to the lack of prospective trials. In this review, we analyze the most relevant biological, molecular, pathological and clinical features of OAML and propose some therapeutic guidelines for patients affected by this malignancy.

Antibodies against heat shock protein 60 derived from Helicobacter pylori: diagnostic implications in cardiovascular disease

Immune responses against heat shock protein 60 (HSP60) of pathogen-origin are thought to be defensive events which, due to molecular mimicry, misdirect to a human counterpart. Therefore, atherosclerosis may be serologically predicted by anti-HSP60 antibodies (Abs). In the present study, we analyzed the clinical prevalence of the serum IgG Abs against Helicobacter pylori (Hp)-derived HSP60 (Hp-HSP60) or its peptide fragments in patients with cardiovascular disease (CVD; n=250), as compared to those in age- and gender-matched non-CVD patients (n=293). Anti-Hp cell lysate Abs frequently appeared in Hp-infected patients who were not associated with CVD. In contrast, Abs against the particular amino acid sequence Hp-HSP60(II3) (II3 region, Glu(141)-Leu(160), in Hp-HSP60) predominantly appeared in CVD patients, as well as IgG anti-human HSP60 (Hu-HSP60(w)). Furthermore, neither titer of anti-Hp-HSP60(II3) nor anti-Hu-HSP60(w) Abs was correlated with the levels of high sensitivity C-reactive protein (hsCRP). This data strongly suggested that IgG anti-Hp-HSP60(II3) Abs cross-reacted with Hu-HSP60(w) were independent diagnostic markers relevant to CVD. Further, the 20 amino acid residues (Glu(141)-Leu(160)) might be predominant CVD-associated epitopes that induce anti-Hu-HSP60 auto-Abs, whose location was predicted in the tertiary structure of Hu-HSP60.

Helicobacter pylori heat-shock protein 60 induces interleukin-8 via a Toll-like receptor (TLR)2 and mitogen-activated protein (MAP) kinase pathway in human monocytes

Previous reports have indicated that Helicobacter pylori heat-shock protein 60 (H. pylori-HSP60), as an immunodominant antigen, induces interleukin (IL)-8 production in human monocytes. The exact mechanism by which H. pylori-HSP60 induces IL-8 production in monocytes has not been fully elucidated. In the present study, the downstream pathway by which H. pylori-HSP60 induces IL-8 secretion in human monocytic cell lines was investigated. Intact H. pylori, heat-killed H. pylori and H. pylori recombinant HSP60 (rHpHSP60) all induced the secretion of IL-8 and the activation of mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK) and p38, but not c-Jun N-terminal kinase (JNK), up to 24 h in NOMO1 cells. The specific inhibitors PD98059 and U0126 (for ERK1/2 signalling) and SB203580 (for p38 MAPK signalling) down-regulated IL-8 secretion from rHpHSP60-treated NOMO1 cells. An anti-Toll-like receptor (TLR)2 antibody or TLR2 small interfering RNA (siRNA) partially inhibited the secretion of IL-8, and anti-TLR2 antibody also suppressed activation of ERK and p38 MAPK in rHpHSP60-treated NOMO1 cells. These reactions were associated with nuclear factor-kappaB (NF-kappaB)-mediated transcriptional activation, since U0126, SB203580 and the anti-TLR2 antibody decreased NF-kappaB activation. Taken together, the results suggest that ERK and p38 MAPK signalling linked to the TLR2 recognition receptor in human monocytes may be an important pathway in H. pylori-HSP60-induced IL-8 secretion.

Clinical outcome of patients with Helicobacter pylori infection: the bug, the host, or the environment?

It is well established that only a minority of patients with Helicobacter pylori infection develop severe inflammation leading to peptic ulcer or gastric cancer. Recent evidence suggests that the virulence factors of the organism do not seem crucial in the progression of inflammation towards a more severe disease. It seems probable that other host derived and environmental factors are more significant in determining clinical outcome but additional studies are needed to clarify the underlying mechanisms involved in the pathogenesis of infection.

Infectious agents in mucosa-associated lymphoid tissue-type lymphomas: pathogenic role and therapeutic perspectives

Mucosa-associated lymphoid tissue (MALT) lymphoma probably constitutes the best in vivo model showing how complex interplay between B lymphocytes and the surrounding microenvironment may lead to a neoplastic disorder. After the seminal discovery of the pathogenic association between Helicobacter pylori and gastric MALT lymphomas, evidence suggests the possible involvement of other infectious agents in the development of MALT lymphomas arising at different body sites. Although several other bacteria (Borrelia burgdorferi, Campylobacter jejuni, and Chlamydia psittaci) and viruses (Hepatitis C virus) seem to play a role in lymphomas presenting at different locations, a possible common pathogenic mechanism is emerging. Several lines of evidence suggest that different infectious agents might provide a chronic antigenic stimulation that elicits host immune responses able to promote clonal B-cell expansion. This model is also substantiated by the increasing number of patients with MALT lymphomas who exhibit objective clinical responses after antimicrobial therapy. A multidisciplinary approach is critical to better understand the complex etiopathogenesis of MALT lymphomas with the final goal to dissect the clinicopathologic heterogeneity of these disorders and design more tailored preventive and therapeutic approaches.

Serum antibodies to Helicobacter pylori and its heat-shock protein 60 correlate with the response of gastric mucosa-associated lymphoid tissue lymphoma to eradication of H. pylori

BACKGROUND AND AIMS

Eradication of Helicobacter pylori leads to regression of mucosa-associated lymphoid tissue (MALT) lymphomas. In this study, we measured serum antibodies to H. pylori and H. pylori-recombinant heat-shock protein 60 (rHSP60) in patients with gastric MALT lymphoma to determine whether humoral immune responses to the bacterial antigens correlate with the efficacy of eradication therapy.

METHODS

Serum samples were obtained from 33 patients with H. pylori-positive gastric MALT lymphoma before undergoing therapy to eradicate the bacteria. Anti-H. pylori antibodies were measured in a commercial assay and in immunoassays to lysates and rHSP60 which were prepared from ATCC 43504 strain.

RESULTS

Helicobacter pylori were eradicated in all 33 patients, and the lymphoma completely regressed histologically in 26 patients (79%). Pre-treatment titers of serum antibody to H. pylori and to rHSP60 in the patients whose tumor regressed were significantly higher than titers in patients whose tumors did not regress (p =.0011 and.035, respectively). By logistic regression analysis, age (odds ratio = 0.88, 95% confidence interval = 0.80-0.99), endoscopic appearance (0.053, 0.004-0.65), titers of anti-H. pylori antibodies (67.6, 2.5-1800), and titers of anti-rHSP60 antibody (6.4, 1.2-36) were identified as significantly associated factors with the outcome of MALT lymphoma.

CONCLUSIONS

Measurement of serum antibodies to H. pylori and HSP60 might be useful for predicting the response of gastric MALT lymphoma to eradication of H. pylori.

Ten kilodalton heat shock protein (HSP10) is overexpressed during carcinogenesis of large bowel and uterine exocervix

In the present study, we evaluated the presence and the level of expression of HSP10 in two carcinogenetic models: the 'adenoma-carcinoma sequence' of large bowel and the 'dysplasia-carcinoma sequence' of uterine exocervix. We found HSP10 was overexpressed during the carcinogenesis of both organs. In particular, HSP10 was overexpressed early in large bowel carcinogenesis, while the expression of this protein in exocervical carcinogenesis gradually increased from normal through dysplastic to neoplastic tissues. The quantitative analysis of immunohistochemistry and the Western blotting confirmed these results. Our previous observations showed overexpression of HSP60 in the same carcinogenetic models. This report correlates the overexpression of HSP10 with that of HSP60 during carcinogenesis in vivo. These results could stimulate further studies on the pathogenetic role of these proteins during the carcinogenesis as well as their use as diagnostic and prognostic tools in oncology.