Gastric MALT lymphoma and Helicobacter pylori.

Primary gastric low-grade B-cell lymphomas are neoplastic mimics of mucosa associated lymphoid tissue (MALT) as exemplified by Peyer''s patches in the terminal ileum. Architectural and immunophenotypic properties of the neoplastic cells suggest that they originate from MALT-derived marginal zone B-cells. Paradoxically, the normal human stomach is devoid of organized MALT within which a lymphoma can develop. Lymphoid tissue is acquired in the stomach in response to antigenic stimulation, predominantly associated with Helicobacter pylori infection. Studies of patients with low-grade MALT lymphoma have confirmed a high incidence of H. pylori infection and suggest that the infection predates neoplastic transformation. Certain morphological features of MALT lymphomas suggest that the tumor cells remain responsive to antigen drive. Given the close association between gastric MALT lymphoma and H. pylori, it is possible that this organism provides such a drive. In vitro studies have shown that the tumor cells proliferate in a T-cell-dependent way to the presence of H. pylori. Several studies have now demonstrated that eradication of the organism in patients with low-grade gastric MALT lymphoma can result in regression of the tumor. In cases with a high-grade component, the associated low-grade part may regress, but most high-grade gastric MALT lymphomas are unresponsive to this conservative therapy.     

Overexpression of miR-142-5p and miR-155 in Gastric Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma Resistant to Helicobacter pylori Eradication

microRNAs (miRNAs) are small non-coding RNAs that can function as endogenous silencers of target genes and play critical roles in human malignancies. To investigate the molecular pathogenesis of gastric mucosa-associated lymphoid tissue (MALT) lymphoma, the miRNA expression profile was analyzed. miRNA microarray analysis with tissue specimens from gastric MALT lymphomas and surrounding non-tumor mucosae revealed that a hematopoietic-specific miRNA miR-142 and an oncogenic miRNA miR-155 were overexpressed in MALT lymphoma lesions. The expression levels of miR-142-5p and miR-155 were significantly increased in MALT lymphomas which do not respond to Helicobacter pylori (H. pylori) eradication. The expression levels of miR-142-5p and miR-155 were associated with the clinical courses of gastric MALT lymphoma cases. Overexpression of miR-142-5p and miR-155 was also observed in Helicobacter heilmannii-infected C57BL/6 mice, an animal model of gastric MALT lymphoma. In addition, miR-142-5p and miR-155 suppress the proapoptotic gene TP53INP1 as their target. The results of this study indicate that overexpression of miR-142-5p and miR-155 plays a critical role in the pathogenesis of gastric MALT lymphoma. These miRNAs might have potential application as therapeutic targets and novel biomarkers for gastric MALT lymphoma.     

Immunoproliferative Small Intestinal Disease and B-Cell MALT Lymphoma of the Digestive Tract

Immunoproliferative small intestinal disease (originally called Mediterranean lymphoma and subsequently alpha chain disease) is a slowly progressive low grade primary small intestinal B-cell lymphoma characterized by the synthesis of a truncated alpha heavy chain without light chain by the neoplastic cells. The histological features of IPSID and low grade primary gastric B-cell lymphoma are closely similar and recapitulate the those of Peyer''s patches. This observation has led to the mucosa associated lymphoid tissue (MALT) lymphoma concept which encompasses a group of extranodal lymphomas including IPSID and primary gastric lymphoma. Unlike nodal low-grade B-cell lymphomas, IPSID and low grade gastric lymphoma remain localized to their sites of origin for prolonged periods. One possible explanation for this is that the growth of these lymphomas is influenced by a local antigen. This is supported by reports of clinical remissions induced in IPSID following sterilization of the small intestine using broad spectrum antibiotics. Similar findings have been reported in low grade gastric lymphoma following eradication of Helicobacter pylori which is almost invariably present in the patients'' stomachs. Laboratory experiments have shown that the growth of lymphomatous B-cells is stimulated via H. pylori specific T-cells. Further work is required to identify the antigen(s) operative in IPSID and, possibly, other low grade B-cell lymphomas.     

Model of angiogenesis in mice with severe combined immunodeficiency (SCID) and xenoengrafted with Epstein-Barr virus-transformed B cells

Xenoengraftment of human cells in mice with severe combined immunodeficiency (SCID) has been used as a model system to study the mechanisms of B-cell lymphomagenesis. In the study reported here, we determined that SCID mice can also be used as a model to study angiogenesis in B-cell lymphomas. The C.B-17 scid/scid mice were xenotransplanted with Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL), and we determined whether CD31, a marker found on endothelial cells, was detected in the human B-cell lymphomas that developed in these mice. Microvessel formation was identified by use of immunohistochemical staining for CD31. To assess possible mechanisms of angiogenic stimulus, we analyzed the expression of interleukin 8 (IL-8), a chemokine documented to promote angiogenesis, in non-small-cell lung cancer and bronchogenic carcinomas. We observed that a panel of LCL and LCL-lymphomas expressed IL-8 mRNA and protein. Neutralization of IL-8, however, did not inhibit lymphomagenesis, suggesting that IL-8 is not essential for angiogenesis in this model. To examine other parameters of angiogenesis, we identified expression of vascular endothelial growth factor in the lymphomas. These data suggest that angiogenesis accompanies EBV-associated B-cell lymphoma development, but IL-8 is not essential for this process. Thus, the SCID mouse model is amenable to testing of anti-angiogenic factors.     

Comparison of localized gastric mucosa-associated lymphoid tissue (MALT) lymphoma with and without Helicobacter pylori infection

BACKGROUND: The clinical features and clinical course of Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue (MALT) lymphoma are unclear and a treatment strategy has not yet been established. AIM: To clarify the clinical differences between H. pylori-positive and H. pylori-negative gastric MALT lymphoma, we compared these two types of gastric MALT lymphoma. MATERIALS AND METHODS: Fifty-seven patients with localized gastric MALT lymphoma were studied. H. pylori infection was present in 41 and absent in 16. Treatment consisted of antibiotic therapy and/or 30 Gy radiation therapy. Response assessment was performed every 3-6 months by esophagogastroduodenoscopy including gathering biopsy samples, endoscopic ultrasonography, clinical examination, and various imaging procedures. The median follow-up period was 37 months. RESULTS: There were no significant differences between H. pylori-positive and H. pylori-negative gastric MALT lymphoma patients in terms of sex, age, stage, gross phenotype, affected area of the stomach, or the presence of monoclonality. Complete regression was achieved with antibiotic therapy against H. pylori-negative gastric MALT lymphoma in one of nine patients (11.1%), compared to 28 of 38 patients (73.7%) with H. pylori-positive gastric MALT lymphoma (p < .001). Radiation therapy showed high effectiveness for the local control of H. pylori-negative or antibiotic-resistant gastric MALT lymphoma (92.9%), although distant recurrence was recognized in three of 14 patients (21.4%). Two of 16 patients (12.5%) with H. pylori-negative gastric MALT lymphoma died because of the transformation of the disease into diffuse large B-cell lymphoma. There was a significant difference in both the overall and cause-specific survival rate between the two groups (p = .038). CONCLUSION: Radiation therapy is the effective treatment for H. pylori-negative or antibiotic-resistant localized gastric MALT lymphoma. However, careful systemic follow-up for distant involvement should be required. Transformation into diffuse large B-cell lymphoma is thought to be the important cause of death in patients with gastric MALT lymphoma.     

Helicobacter pylori (H. pylori) molecular signature in conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma

Conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma is an extranodal marginal zone B-cell lymphoma that is characterized by an exaggerated clonal expansion of B cells, which implicate a pathological proliferative response to antigen(s) including bacteria. Helicobacter pylori (H. pylori) infection is recognized as one of the causative agents of gastric MALT lymphoma; however, it has not been reported in extra gastric MALT lymphoma. We studied 5 patients (4 adults and 1 child) with salmon-colored conjunctival lesions. One patient also had a history of abnormal bone marrow biopsy a year earlier with lymphoid aggregates involving 5% of the overall bone marrow. The conjunctival lesions of the 5 patients were biopsied. Histopathological diagnoses were consistent with conjunctival MALT lymphoma. Lymphoma and normal conjunctival cells were microdissected using laser capture microscopy or manual techniques. DNA was extracted and subjected to PCR amplification using H. pylori gene-specific primers from the urease B and vac/m2 gene. Cells from chronic conjunctivitis (normal lymphocytes), conjunctival human T-cell lymphotropic virus type-1/adult T-cell leukemia/lymphoma (HTLV-1/ATL), and orbital B-cell lymphoma were also microdissected, processed and analyzed. PCR amplification and Southern blot hybridization demonstrated H. pylori DNA in the conjunctival MALT lymphoma cells of 4/5 cases. The negative case was the one with a history of abnormal bone marrow. In contrast, H. pylori gene was not detected in normal conjunctival cells from the cases of MALT lymphoma or the lymphocytes, ATL and orbital B-lymphoma cells from the controls. These data suggest that H. pylori may play a role in conjunctival MALT lymphoma.     

Helicobacter pylori infection and gastrin and cyclooxygenase expression in gastric and colorectal malignancies

Helicobacter pylori, infecting more than 50% of the world population, results in gastritis, usually located in the antral portion of the stomach, accompanied by hypergastrinemia, the key factor in gastric and colorectal carcinogenesis. Excessive mucosal cell proliferation for many years may eventually result in gastric atrophy, cell mutation and transformation of gastric mucosal cells into gastrin-producing cells, which also express gastrin receptors serving to stimulate cell proliferation and tumor growth. These processes may be completed by the expression of cyclooxygenase-2 (COX-2) as an inflammation enzyme to release excessive amounts of PGE(2), leading to further proliferation, reduction in apoptosis, angiogenesis and tumor growth. H. pylori eradication results in complete regression of MALT lymphoma and subsequent normalisation of excessive gastrin release and COX-2 expression. Reduction of gastrin by active immunisation (gastrimmune), blocking of gastrin receptors with specific blockers and suppression of COX-2 might be helpful in inhibiting tumor growth and invasion.     

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.     

Calcitonin gene-related peptide facilitates revascularization during hindlimb ischemia in mice

It is known that the neural system plays a fundamental role in neovascularization. A neuropeptide, calcitonin gene-related peptide (CGRP), is widely distributed in the central and peripheral neuronal systems. However, it remains to be elucidated the role of CGRP in angiogenesis during ischemia. The present study examined whether endogenous CGRP released from neuronal systems facilitates revascularization in response to ischemia using CGRP knockout mice (CGRP-/-). CGRP-/- or their wild-type littermates (CGRP+/+) were subjected to unilateral hindlimb ischemia. CGRP-/- exhibited impaired blood flow recovery from ischemia and decreased capillary density expressed in terms of the number of CD-31-positive cells in the ischemic tissues compared with CGRP+/+. In vivo microscopic studies showed that the functional capillary density in CGRP-/- was reduced. Hindlimb ischemia increased the expression of pro-CGRP mRNA and of CGRP protein in the lumbar dorsal root ganglia. Lack of CGRP decreased mRNA expression of growth factors, including CD31, vascular endothelial growth factor-A, basic fibroblast growth factor, and transforming growth factor-β, in the ischemic limb tissue. The application of CGRP enhanced the mRNA expression of CD31 and VEGF-A in human umbilical vein endothelial cells (HUVECs) and fibroblasts. Subcutaneous infusion of CGRP8-37, a CGRP antagonist, using miniosmotic pumps delayed angiogenesis and reduced the expression of proangiogenic growth factors during hindlimb ischemia. These results indicate that endogenous CGRP facilitates angiogenesis in response to ischemia. Targeting CGRP may provide a promising approach for controlling angiogenesis related to pathophysiological conditions.     

Helicobacter felis and Helicobacter bizzozeronii induce gastric parietal cell loss in Mongolian gerbils

Non-pylori helicobacter infections are associated with gastritis, gastric ulcers and MALT lymphomas in man. Approximately 50% of these are caused by helicobacters commonly found in dogs and cats, including Helicobacter felis, Helicobacter bizzozeronii and H. salomonis. In contrast to Helicobacter pylori, the virulence mechanisms of these species are unknown. In this study the virulence of H. felis, H. bizzozeronii and H. salomonis was investigated in Mongolian gerbils. Female SPF gerbils were inoculated intragastrically with H. felis, H. bizzozeronii or H. salomonis and sacrificed 3 weeks later. Fundus and antrum samples were taken for bacterial detection by PCR. A longitudinal strip covering all stomach regions was taken for histology. Gastric colonization, inflammation, apoptosis, loss of parietal cells and cell proliferation were assessed. Controls and H. salomonis inoculated gerbils were negative in PCR. H. felis and H. bizzozeronii inoculated animals were positive. H. felis inoculated animals showed loss of parietal cells extending from the limiting ridge into the fundus. A high cell proliferation rate was noticed in the mucosal area devoid of parietal cells. A dense band of apoptotic cells and large numbers of Helicobacter bacteria were seen at the transition zone between affected and normal parietal cells. In H. bizzozeronii infected gerbils, this was less pronounced. Focal apoptotic loss of gastric epithelial cells was spatially associated with the presence of bacteria especially in H. felis and to a lesser extent in H. bizzozeronii infected gerbils. This loss of cells may lead to intestinal metaplasia.     

Variations in MALT1 Gene Disruptions Detected by FISH in 109 MALT Lymphomas Occurring in Different Primary Sites

Mucosa-associated lymphoid tissue (MALT) lymphoma is a type of B-cell non-Hodgkin lymphoma that can originate in the gastrointestinal (GI) tract, thyroid, breasts, lungs, and skin. The most common genetic abnormality occurring in MALT lymphomas involves t(11;18)(q21;q21) in the gene MALT1. This translocation results in a chimeric fusion product between the genes ATI2 and MALT1, which generates a survival advantage in the lymphoma cells. The MALT1 disruption is more common in some MALT lymphomas, distinguished by site, than others. If identified, this variation in frequency could affect treatment courses and outcomes for each type of MALT lymphoma. The study included 109 MALT lymphoma sample specimens. The sample paraffin-embedded slides were pretreated, hybridized for FISH using a MALT1 break-apart probe, post-washed, and viewed using a fluorescent microscope. On each slide, 100 individual cells were counted by two independent readers, totaling 200 cells per case, and the percentage of cells containing a translocation within each sample was recorded. A conservative threshold of 8% was used to make a positive call. There were a total of 18 positive results in the 109 samples tested. The tissue specimens tested that yielded positive results include the colon (62.5%), lung (57.14%), skin (25%), eyelid/lacrimal gland (16.67%), stomach (6.45%), kidney (50%), and thyroid (100%). The sites that yielded only negative results (0%) include the breast, salivary gland, salivary gland/parotid, soft tissue/skin, conjunctiva/orbital, small intestine, nasal, and epidural mass. As hypothesized, a variation in the MALT1 disruption was found. This is the first study to examine MALT1 disruption in the soft tissue, nasal, and epidural mass. The positive results of this study, specifically the results for the colon and lung, and the negative breast and salivary gland results are consistent with previous studies examining the genetic aberrations in MALT lymphomas. These results indicate that MALT lymphoma at different locations differentially display MALT1 disruption, and these disruptions may be responsible for the variance in patient response to therapy. Surgery, radiation therapy, and/or administration of cladribine (2CdA) result in the best outcomes in treating MALT lymphomas with MALT1 disruption.     

Shp-1 mediates the antiproliferative activity of tissue inhibitor of metalloproteinase-2 in human microvascular endothelial cells

The tissue inhibitors of metalloproteinases (TIMPs) regulate matrix metalloproteinase activity required for cell migration/invasion associated with cancer progression and angiogenesis. TIMPs also modulate cell proliferation in vitro and angiogenesis in vivo independent of their matrix metalloproteinase inhibitory activity. Here, we show that TIMP-2 mediates G1 growth arrest in human endothelial cells through de novo synthesis of the cyclin-dependent kinase inhibitor p27Kip1. TIMP-2-mediated inhibition of Cdk4 and Cdk2 activity is associated with increased binding of p27Kip1 to these complexes in vivo. Protein-tyrosine phosphatase inhibitors or expression of a dominant negative Shp-1 mutant ablates TIMP-2 induction of p27Kip1. Finally, angiogenic responses to fibroblast growth factor-2 and vascular endothelial growth factor-A in "motheaten viable" Shp-1-deficient mice are resistant to TIMP-2 inhibition, demonstrating that Shp-1 is an important negative regulator of angiogenesis in vivo.     

Semaphorin 4A exerts a proangiogenic effect by enhancing vascular endothelial growth factor-A expression in macrophages

The axon guidance cues semaphorins (Semas) and their receptors plexins have been shown to regulate both physiological and pathological angiogenesis. Sema4A plays an important role in the immune system by inducing T cell activation, but to date, the role of Sema4A in regulating the function of macrophages during the angiogenic and inflammatory processes remains unclear. In this study, we show that macrophage activation by TLR ligands LPS and polyinosinic-polycytidylic acid induced a time-dependent increase of Sema4A and its receptors PlexinB2 and PlexinD1. Moreover, in a thioglycollate-induced peritonitis mouse model, Sema4A was detected in circulating Ly6C(high) inflammatory monocytes and peritoneal macrophages. Acting via PlexinD1, exogenous Sema4A strongly increased macrophage migration. Of note, Sema4A-activated PlexinD1 enhanced the expression of vascular endothelial growth factor-A, but not of inflammatory chemokines. Sema4A-stimulated macrophages were able to activate vascular endothelial growth factor receptor-2 and the PI3K/serine/threonine kinase Akt pathway in endothelial cells and to sustain their migration and in vivo angiogenesis. Remarkably, in an in vivo cardiac ischemia/reperfusion mouse model, Sema4A was highly expressed in macrophages recruited at the injured area. We conclude that Sema4A activates a specialized and restricted genetic program in macrophages able to sustain angiogenesis and participates in their recruitment and activation in inflammatory injuries.     

Influence of polymorphisms in the NOD1/CARD4 and NOD2/CARD15 genes on the clinical outcome of Helicobacter pylori infection

Host immune response influences the clinical outcome of Helicobacter pylori infection leading to ulcer disease, gastric carcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. A genetic risk profile for gastric cancer has been identified, but genetic susceptibility to develop MALT lymphoma is still unclear. We investigated the role of NOD1 and NOD2 as intracellular recognition molecules for pathogen-associated molecules in H. pylori infection in vitro and analysed the influence of single nucleotide polymorphisms on susceptibility to ulcer disease and MALT lymphoma. Expression of NOD1 and NOD2 significantly sensitized HEK293 cells to H. pylori-induced NF-kappaB activation in a cag pathogenicity island (cagPAI)-dependent manner. In cells carrying the Crohn-associated NOD2 variant R702W the NF-kappaB response was significantly diminished. NOD1/NOD2 expression levels were induced in the gastric epithelium in H. pylori-positive patients. No mutations were found to be associated with gastritis or gastric ulcer development. However, the R702W mutation in the NOD2/CARD15 gene was significantly associated with gastric lymphoma. Carrier of the rare allele T had a more than doubled risk to develop lymphoma than controls [odds ratio (OR): 2.4, 95% confidence interval (CI): 1.2-4.6; P < 0.044]. H. pylori-induced upregulation of NOD1 and NOD2 in vivo may play a critical role in the recognition of this common pathogen. A missense mutation in the leucine-rich region of CARD15 is associated with gastric lymphoma.     

Immunohistochemical comparison of CD5, lambda,and kappa expression in primary and recurrent buccal Mucosa-associated lymphoid tissue (MALT) lymphomas

Mucosa-associated lymphoid tissue (MALT) lymphoma is a type of extranodal marginal zone B-cell lymphoma and is a distinct subtype of non-Hodgkin's lymphoma.Primary MALT lymphomas can also occur in the oral cavity, although their appearance in this location is rare. The neoplastic cells of which MALT lymphomas are composed express B-cell antigens and show monotypic immunoglobulin expression with light-chain restriction.Although neoplastic MALT lymphoma cells do not express CD5, previous studies have shown that CD5 positive MALT lymphomas are more prone to dissemination than those that do not express CD5. Moreover, there are some reports that describe kappa- and lambda- dual light chain expression in B cell malignant neoplasms.A 66-year-old Japanese woman with swelling of the right buccal mucosa was referred to our hospital. The lesion was excised and was pathologically diagnosed as a MALT lymphoma tumor with a t(11;18)(q21;q21) chromosome translocation.Swelling of the right buccal mucosa recurred 2 years later. The recurrent tumor was then excised and pathologically diagnosed as MALT lymphoma.Immunohistochemical examination of CD5, lambda, and kappa expressions revealed that the primary tumor was positive for CD5, kappa, and lambda, but the recurrent tumor was weakly positive for CD5 and kappa.With respect to lambda positivity, the recurrent tumor showed negativity.Our study suggests that immunohistochemical expression of CD5, kappa, and lambda in oral MALT lymphoma have the risk of recurrence.We first described the recurrence of CD5 positive MALT lymphoma in the oral cavity and compared the immunohistochemical expressions of CD5, lambda, and kappa between the primary and recurrent tumors.     

BCL-6 mutations in pulmonary lymphoproliferative disorders: demonstration of an aberrant immunological reaction in HIV-related lymphoid interstitial pneumonia

We used a PCR and sequence procedure to analyze the Ig V(H) gene and the mutations in the 5' regulatory regions of BCL-6 genes in pulmonary lymphoproliferative disorders (mucosa-associated lymphoid tissue (MALT) lymphoma, HIV-related, EBV-related, and virus-negative lymphocytic interstitial pneumonia (LIP)). Eight of 20 (40%) pulmonary MALT lymphoma and 10 of 20 LIP (5 of 5 (100%) HIV-related, 2 of 5 (40%) EBV-related, and 3 of 10 (30%) virus-negative LIP) cases showed BCL-6 gene mutations. Intraclonal heterogeneity of the BCL-6 mutations was observed only in pulmonary MALT lymphoma cases whose Ig V(H) genes also showed intraclonal heterogeneity. Ongoing BCL-6 mutations might reflect re-entry into a germinal center pathway to further mutations. BCL-6 mutations in pulmonary MALT lymphoma and HIV-negative LIP showed some features (high transition to transversion ratio, standard polarity, and RGYW/WRCY bias) of Ig V(H) gene hypermutation, leading to the view that pulmonary MALT lymphomas and HIV-negative LIP are under the influence of germinal center hypermutation mechanisms. Because BCL-6 mutations in HIV-related LIP cases did not demonstrate features of Ig V(H) gene hypermutation, immunological reactions in HIV-related LIP are the result of a process different from that found in HIV-negative pulmonary lymphoproliferative disorders.     

Angiogenesis and diabetes: different responses to pro-angiogenic factors in the chorioallantoic membrane assay

Hyperglycemia induces defects in angiogenesis without alteration in the expression of major vascular growth factors in the chicken chorioallantoic membrane (CAM) model. A direct negative effect of hyperglycemia on angiogenesis may participate in failures of "therapeutic angiogenesis" trials. Here, we tested the hypothesis that the response to pro-angiogenic molecules such as angiotensin-converting enzyme (ACE), endothelin-1 (ET-1), and vascular endothelial growth factor-A (VEGF) is altered by hyperglycemia. Transfected (Chinese hamster ovary [CHO] or human embryonic kidney [HEK]) cells overexpressing ACE, ET-1, or VEGF were deposed onto the CAM of hyperglycemic or control embryos. The proangiogenic effect was evaluated 3 d later by angiography and histological analyses. Gene expression in response to these factors was assessed by in situ hybridization. Only VEGF overexpression evoked a proangiogenic response in the CAM from hyperglycemic embryos, upregulating the expression of endogenous VEGF, VEGF-R2, and Tie-2, all of them related to activation of endothelial cells. In conclusion, in a model where hyperglycemia does not alter the major vascular growth factor expression, the negative effect of diabetes on capillary density was overcome only by VEGF overexpression, whereas responses to other vasoactive peptides were practically abolished under hyperglycemic conditions.     

To sprout or to split? VEGF, Notch and vascular morphogenesis

Therapeutic angiogenesis is an attractive strategy to treat patients suffering from peripheral or coronary artery disease. VEGF (vascular endothelial growth factor-A) is the fundamental factor controlling vascular growth in both development and postnatal life. The interplay between the VEGF and Notch signalling pathway has been recently found to regulate the morphogenic events leading to the growth of new vessels by sprouting. Angiogenesis can also take place by an alternative process, i.e. intussusception or vascular splitting. However, little is known about its role in therapeutic angiogenesis and its molecular regulation. In the present article, we briefly review how VEGF dose determines the induction of normal or aberrant angiogenesis and the molecular regulation of sprouting angiogenesis by Notch signalling, and compare this process with intussusception.     

Expression cloning of cholesterol alpha-glucosyltransferase, a unique enzyme that can be inhibited by natural antibiotic gastric mucin O-glycans, from Helicobacter pylori

Helicobacter pylori infects over half the world's population, but only 3% of those infected develop peptic ulcer, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma. In H. pylori, alpha-glucosyl cholesterol constitutes more than 25% of cell wall lipids, and it has been suggested that alpha-glucosyl cholesterol is essential for H. pylori viability. Here, we identified cholesterol alpha-glucosyltransferase (CHLalphaGcT) using an expression cloning strategy and showed that this enzyme is distinctively inhibited by mucin-type O-glycans similar to those present in deeper portions of the gastric mucosa. Moreover, inactivation of CHLalphaGcT by homologous recombination led to H. pylori lethality. These results indicate that H. pylori CHLalphaGcT is a unique enzyme targeted by a natural antibiotic mucin and constitutes an excellent therapeutic target to prevent H. pylori-induced peptic ulcer, gastric carcinoma, and MALT lymphoma.