Abstract

Helicobacter pylori phospholipase A (OMPLA) degrades bacterial membrane phospholipids to lysophospholipids. High levels of lysophospholipids are associated with higher hemolytic activity, increased release of urease and vacA and better adherence to epithelial cells in vitro. The phospholipase A gene (pldA) displays phase variation due to a slippage in a homopolymeric tract. The aim of this study was to determine if the relative amount of lysophospholipids in the cell wall is associated with ulcer disease, and to further investigate the significance of pldA phase variation. H. pylori isolates of 40 patients were examined. The relative lysophospholipid content of each isolate was determined and the pldA gene was sequenced. The study indicated that H. pylori can regulate its OMPLA activity by phase variation in the pldA gene or by protein level regulation among phase variants in the pldA ‘ON’ status. We found a significant difference between the relative amount of lysophospholipids of the ulcer group and the non-ulcer group (p = 0.022). When the lysophospholipid/phospholipid ratios were compared with outcome, the OR for ulcer disease was 9.0 (95% CI 1.6–49.4; p = 0.014). Isolates with a high OMPLA activity are significantly associated with patients with ulcer disease.

Keywords: Helicobacter pylori; Outer membrane phospholipase A; Phospholipid; Duodenal and gastric ulcer

Article Outline

1. Introduction

2. Materials and methods

2.1. Patients

2.2. Bacterial strains and cultivation conditions

2.3. Lipid extraction and phospholipid quantification

2.4. DNA extraction and sequence determination

2.5. Study of the heterogeneity in homopolymeric tracts from single patients

2.6. Amplified fragment length polymorphism

2.7. Amplification of vacA, cagA and iceA by PCR

2.8. Statistical analyses

3. Results

3.1. LysoPE/PE ratio

3.2. Sequencing of the pldA gene

3.3. Study of the heterogeneity in homopolymeric tracts from single patients

4. AFLP

4.1. cagA, vacA and iceA genotyping

5. Discussion

References