Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for...

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Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood Akhtar, George L. Mendz, Jamie C. Newton, Yulan Cheng, Harry L. T. Mobley, and Keith T. Wilson Presented by Mihaela C. Badea-Mic

Transcript of Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for...

Page 1: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survivalAlain P. Gobert, David J. McGee, Mahmood Akhtar, George L. Mendz, Jamie C. Newton, Yulan Cheng, Harry  L. T. Mobley,  and Keith T. Wilson

Presented by Mihaela C. Badea-Mic

Page 2: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

So, Who Am I?

• Gram negative bacteria

inside the stomach

and duodenum

The Helicobacter Foundation

Page 3: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Who discovered me?

• 1983-Campylobacter pyloridis

• 1997- Tomb et al sequenced the HP genome

• The Helicobacter Foundation,

2005

Page 4: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Epidemiology

• Prevalence (USA)• African-American

• Hispanic

• Eastern Europeans

• UBIQUITOUS

• 50% world population

• The Helicobacter Foundation, 2005

Page 5: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Pathophysiology

• The most common route of H. Pylori infection• Oral to oral• Fecal to oral

PS: watch your pets!

Page 6: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Histology

The Helicobacter Foundation, 2005

Page 7: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Diagnosis

・ Breath test

- Based on the detection of the products of urea

The Helicobacter Foundation, 2005

Page 8: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Diagnosis- cont.

・ Esophagogastroduodenoscopy with biopsy

・ H. Pylori fecal antigen

・ H. Pylori serology

Page 9: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Diseases

The Helicobacter Foundation, 2005

Page 10: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Diseases- cont.

• Gastric and duodenal ulcers

• Gastric cancer ( 90%)

• Non-ulcer dyspepsia

• Weird syndromes

Page 11: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Treatment

• Antidiarrheals – bistmuth

• Antibiotics - metronidazole, tetracycline, amoxicilin

• Proton pump inhibitors - omeprazole, lansoprazole

• H2 receptor blockers – ranitidine, famotidine

Page 12: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

My survival strategies

D. S. Merrel et al, 2004

Page 13: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

My virulence factors

D. M. Monack et al, 2004

Page 14: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Details

D. M. Monack et al, 2004

Page 15: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

And now…finally the paper

• Activated macrophages produce NO using L-arginine as a substrate

• H. Pylori arginase competes with NOS2 for the substrate

• H. Pylori converts the substrate to urea and L-ornithine, not NO

• rocF gene encodes arginase

• Mutations in rocF gene helps the NO to kill H. Pylori

Page 16: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 1A

• Hypothesis - the activated macrophage production of NO is inhibited by wt H. Pylori at physiologic L-arginine concentrations

Page 17: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment #1A – cont.

Conclusion:

-only the wt H. Pylori inhibited NO released

- the arginase deficient H. Pylori did not inhibit

Page 18: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 1B

• Conclusion:

adding more substrate will stop the competitive inhibition between H. pylori and activated macrophages

Page 19: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 2

• Hypothesis – H. Pylori wt compete for the same substrate with activated macrophages. This substrate is L-arginine .

Page 20: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 2 –cont.

Conclusion-the wt H. Pylori uses L-arginine decreasing the macrophage NO production because of the loss of the substrate- the rocF mutant does not use the L-arginine

Page 21: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 3

• Hypothesis – the macrophage production of NO is regulated by the H. Pylori arginase independently of iNOS expression

• Conclusion- both H. Pylori induce iNOS mRNA expression

Page 22: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 4

• Hypothesis – The bacterial arginase inhibits the release of NO by preformed iNOS in macrophages.

Page 23: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 4-cont

• Conclusion:

the wt H. Pylori inhibits macrophage NO production by the preactivated cells

Page 24: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 5

• Hypothesis – Only viable H.pylori can inhibit the release of macrophage NO

• Conclusion : only live H. Pylori can consume the substrate in order to inhibit the iNOS

Page 25: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 6

• Hypothesis – Inhibition of the host cell NO production is a survival strategy for H. Pylori .

• Conclusion – the wt H. Pylori has an increased rate of survival in comparison with rocF mutant H. Pylori in the presence of macrophages .

Page 26: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 6 A

Page 27: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Experiment # 6B

Conclusion:The rocF mutant H. Pylori survives in the presence of iNOS -/- macrophages.

Page 28: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Summary

• Bacterial arginase evolutionary adaptation survival strategy for H. pylori gastric mucosa protection

Page 29: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Don’t let your kids kiss us!

The Helicobacter Foundation, 2005

Page 30: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

Invitation

Page 31: Helicobacter pylori arginase inhibits nitric oxide production by eukaryotic cells: A strategy for bacterial survival Alain P. Gobert, David J. McGee, Mahmood.

That is all I had to say…

• The End!