Bruna Maria Roesler

Virulence Factors of Helicobacter pylori: A Review

Helicobacter pylori is a spiral-shaped Gram-negative bacterium that colonizes the human stomach and can establish a long-term infection of the gastric mucosa, a condition that affects the relative risk of developing various clinical disorders of the upper gastrointestinal tract, such as chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma. H. pylori presents a high-level of genetic diversity, which can be an important factor in its adaptation to the host stomach and also for the clinical outcome of infection. There are important H. pylori virulence factors that, along with host characteristics and the external environment, have been associated with the different occurrences of diseases. This review is aimed to analyzing and summarizing the main of them and possible associations with the clinical outcome.

Extragastric manifestations of Helicobacter pylori infection: Possible role of bacterium in liver and pancreas diseases

Helicobacter pylori (H. pylori) is an ancient microorganism that has co-evolved with humans for over 60000 years. This bacterium typically colonizes the human stomach and it is currently recognized as the most common infectious pathogen of the gastroduodenal tract. Although its chronic infection is associated with gastritis, peptic ulcer, dysplasia, neoplasia, MALT lymphoma and gastric adenocarcinoma, it has been suggested the possible association of H. pylori infection with several extragastric effects including hepatobiliary and pancreatic diseases. Since a microorganism resembling H. pylori was detected in samples from patients with hepatobiliary disorders, several reports have been discussed the possible role of bacteria in hepatic diseases as hepatocellular carcinoma, cirrhosis and hepatic encephalopathy, nonalcoholic fatty liver disease and fibrosis. Additionally, studies have reported the possible association between H. pylori infection and pancreatic diseases, especially because it has been suggested that this infection could change the pancreatic physiology. Some of them have related a possible association between the microorganism and pancreatic cancer. H. pylori infection has also been suggested to play a role in the acute and chronic pancreatitis pathogenesis, autoimmune pancreatitis, diabetes mellitus and metabolic syndrome. Considering that association of H. pylori to liver and pancreas diseases needs further clarification, our work offers a review about the results of some investigations related to the potential pathogenicity of H. pylori in these extragastric diseases.

Evaluation of five DNA extraction methods for detection of H. pylori in formalin-fixed paraffin-embedded (FFPE) liver tissue from patients with hepatocellular carcinoma

Since Helicobacter spp. DNA was identified in liver tissue resected from patients with hepatocelullar carcinoma (HCC), researchers have suggested a role of this bacterium in hepatic carcinogenesis. Archives of formalin-fixed, paraffin-embedded (FFPE) tissues represent an extraordinary source for clinical studies providing many advantages. However, DNA extraction from FFPE tissues is laborious, time-consuming and still remains a challenge. The aim of this study was to evaluate five protocols for DNA extraction from FFPE liver obtained from patients with HCC in order to detect Helicobacter pylori DNA. These methods were: (1) QIAamp FFPE Tissue Kit, (2) QIAamp DNA Mini Kit, (3) Wizard SV Genomic DNA Purification System, (4) RealiaPrep FFPE gDNA Miniprep System and (5) phenol-chloroform. H. pylori detection was performed using 16S rRNA gene amplification by PCR. The highest total amount of DNA was obtained using the phenol-chloroform method. Analyses of 16S rRNA gene amplification did not show statistically significant differences among the methods (p=0.466), although the highest percentage of positive cases (70%) was found in samples extracted with phenol-chloroform. We suggest that of the five methods evaluated, phenol/chloroform is the most suitable for detection of H. pylori in FFPE liver from patients with HCC.

Eradication Treatment of Helicobacter pylori Infection: Its Importance and Possible Relationship in Preventing the Development of Gastric Cancer

Helicobacter pylori is the most important carcinogen for gastric adenocarcinoma. Bacterial virulence factors are essential players in modulating the immune response involved in the initiation of carcinogenesis in the stomach; host genetic factors contribute to the regulation of the inflammatory response and to the aggravation of mucosal damage. In terms of environmental factors, salt intake and smoking contribute to the development of lesions. Various therapeutic schemes are proposed to eradicate H. pylori infection, which could potentially prevent gastric cancer, offering the greatest benefit if performed before premalignant changes of the gastric mucosa have occurred.

Virulence Factors of Helicobacter pylori and Their Relationship with the Development of Early and Advanced Distal Intestinal Type Gastric Adenocarcinoma

The first isolation of Helicobacter pylori (H. pylori) in 1980s by Marshall and Warren (Marshall & Warren, 1984) ushered in a new era in gastric microbiology, and, in conjunction with increased interest in the pathogenesis of gastroduodenal diseases, has led to important breakthroughs in medical care (Dunn et al., 1997). H. pylori is a spiral-shaped gram-negative flagellate bacterium that demonstrates bluntly rounded ends in gastric biopsy specimens (Goodwin et al., 1987). H. pylori organisms are 2.5 to 5.0 μm long and 0.5 to 1.0 μm wide, with four to six polar sheathed flagellas, which are essential for bacterial motility (Goodwin & Armstrong, 1990). H. pylori was the first pathogenic microorganism that had its genome sequenced in two different strains. In 1997, H. pylori strain 26695 was firstly isolated from an English patient with chronic gastritis and then sequenced. It had a circular chromosome composed of 1.667.867 base pairs (Tomb et al., 1997). In 1999, strain J99 was isolated from an American patient with duodenal ulcer and then sequenced. This presented a similar, overall genomic organization, gene order and prediction of proteomes when compared to strain 26695 (Alm et al., 1999). In 2006, a chronic atrophic gastritis strain, HPAG1, was isolated and sequenced from a Swedish old patient (Oh et al., 2006). More recently, strain G27 was isolated from an Italian patient and had a similar size to the other three strains (Baltrus et al., 2009). Finally, other strains were sequenced, such as Shi470, B128 and 98-10 (McClain et al., 2009; Thiberge et al., 2010). The finding of strain-specific genes from the comparison of the sequenced strains is in agreement with the earlier studies which demonstrated the high diversity of the H. pylori genome (Akopyanz et al., 1992; Han et al., 2003). Consequently, this high level of genetic diversity can be an important factor in its adaptation to the host stomach and also for the clinical outcome of the infection, an aspect that remains unclear. However, it is thought to involve an interplay between the virulence of the infecting strain, host genetics and environmental factors (Kabir, 2009) and experience with other bacterial pathogens suggests that H. pylori-specific factors may exist that influence the microorganism pathogenicity.

Molecular Epidemiology of Helicobacter pylori in Brazilian Patients with Early Gastric Cancer and a Review to Understand the Prognosis of the Disease

Helicobacter pylori (H. pylori) is an universally distributed bacterium that affects more than half of the world population and is considered an important public health problem. Although colonization with H. pylori is not actually a disease, it is a condition that affects the relative risk of developing various clinical disorders of the upper gastrointestinal tract, as chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT lymphoma) and gastric adenocarcinoma, and, possibly, extradigestive diseases.

From Gastritis to Gastric Cancer: The Importance of CagPAI of Helicobacter Pylori on the Development of Early and Advanced Gastric Adenocarcinoma

In 1984, Warren and Marshall isolated a bacterium from human stomachs in some patients with gastrointestinal disorders [2]. The organism was initially named “Campylobacter-like or‐ ganism”, “Campylobacter pyloridis” and “Campylobacter pylori”, and, after more studies, it is named Helicobacter pylori (H. pylori) in recognition of the fact that this organism is distinct from members of the genus Campylobacter [3].

Mo1781 Molecular Detection of Helicobacter pylori in Formalin-Fixed Paraffin-Embedded (FFPE) Liver Tissue From Patients With Hepatocellular Carcinoma: Comparison of Five Methods to Extract Genomic DNA

hepatocellular carcinoma represents one of the most common human cancers in the world, the aim of this study was to investigate the presence of H. pylori DNA in the FFPE liver from Brazilian patients with HCC. For this purpose, paraffin sections of 38 liver biopsies were used and genomic DNA was extracted using phenol/chloroform method. After that, polymerase chain reaction (PCR) analysis was carried out using H. pylori specific 16S rRNA primers and PCR products of positive samples were further identified by DNA sequencing. Results showed that 14 of the 38 samples (36,8%) amplified the 16S rRNA H. pylori gene. The nucleotide sequence of the 16S rRNA amplicons demonstrated 98% similarity to H. pylori. Considering the H. pylori positive patients, in relation to viral infection, 9 of the 14 (64%) subjects were infected by hepatitis C virus (HCV), 2 (14%) were infected by hepatitis B virus (HBV); 1 (7%) presented coinfection with HCV and HBV and 2 (15%) patients had HCC without viral infection. These data confirm the identification of H. pylori in FFPE liver tissue of Brazilian patients with hepatocellular carcinoma. Additionally, patients infected with H. pylori were most frequently infected by HCV. Further studies will be performed in these samples to detect other H. pylori molecular markers such as cagA, vacA and ureA genes and its association with viral status of patients with HCC. This study was supported by grants from FAPESP ( 2009/09889-5) and FAEPEX (10111)