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Cell-associated haemolytic activity of Helicobacter pylori
Abstract:
Helicobacter pylori cells cultured on solid medium were quantitatively tested for haemolytic activity against erythrocytes of man, sheep, the guinea pig and rabbit. Using 4-day and 8-day cultures of two standard strains (ATCC 43504, IMMi 676), human erythrocytes were not lysed by 10% bacterial suspensions. Rabbit erythrocytes were the most sensitive to 8-day cultures. Hot-cold incubation yielded the highest haemolysis titres. The extent of haemolysis strongly correlated with the number of bacterial cells. Supplementation of the test medium (PBS, pH 7.4) with L-cysteine, dithiothreitol, MgCl2, EDTA, cholesterol, lecithin or sphingomyelin did not influence the haemolysis titres. They were significantly reduced in the presence of pronase E, human serum, bovine serum albumin or CaCl2, and by heat treatment of the bacteria. Supplementation of the test medium with cardiolipin strongly increased the haemolysis titres. Comparing the cell-associated haemolytic activity of 18 strains, the titres ranged from < 2 to 64, with a median titre of 16. No correlation was found between the haemolytic activity and phospholipase C activity of the cell suspensions. It was concluded that the formation of lysophosphatides and non-enzymatic factors rather than a sulphydryl-activated cytolysin or phospholipase C are responsible for the cell-associated haemolytic activity. This property may be involved in the pathogenicity and virulence of Helicobacter pylori.
Insights
Helicobacter pylori exhibits cell-associated hemolytic activity, primarily due to lysophosphatides and non-enzymatic factors, not phospholipase C. This activity may contribute to the bacterium's pathogenicity and virulence.
Area of Science:
- Microbiology
- Pathogenesis
- Biochemistry
Background:
- Helicobacter pylori is a significant human pathogen associated with various gastrointestinal diseases.
- Understanding bacterial virulence factors is crucial for developing effective therapeutic strategies.
Purpose of the Study:
- To quantitatively assess the hemolytic activity of Helicobacter pylori.
- To investigate the factors influencing this hemolytic activity and its potential role in pathogenicity.
Main Methods:
- Quantitative hemolytic assays were performed on erythrocytes from humans, sheep, guinea pigs, and rabbits using various Helicobacter pylori culture ages.
- The influence of different medium supplements, inhibitors, and heat treatment on hemolysis was evaluated.
- Correlation with phospholipase C activity and comparison across 18 bacterial strains were conducted.
Main Results:
- Rabbit erythrocytes were most sensitive to hemolysis by 8-day cultures; hot-cold incubation maximized titres.
- Hemolysis correlated with bacterial cell numbers and was significantly reduced by pronase E, serum proteins, CaCl2, and heat.
- Cardiolipin supplementation strongly increased hemolysis, while L-cysteine, MgCl2, and EDTA had no effect.
Conclusions:
- Cell-associated hemolytic activity of Helicobacter pylori is mainly mediated by lysophosphatides and non-enzymatic factors.
- The study suggests that a sulphydryl-activated cytolysin or phospholipase C are not the primary drivers of this activity.
- This hemolytic property may play a role in the pathogenicity and virulence of Helicobacter pylori infections.