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Innovative vaccine underway to prevent stomach cancer while preserving important gut bacteria

Institute News
Friday, May 15, 2015 - 10:00pm
How do you develop a vaccine to combat potentially fatal bacteria that on the one hand, can cause stomach cancer, but on the other could prevent oesophageal cancer and asthma?

Murdoch Children's Research Institute scientist A/Professor Phil Sutton may have found a solution to the conundrum posed by the tricky bacteria, Helicobacter pylori (H. pylori), that infects about half the world’s population. A/Professor Sutton has potentially found a way to produce a vaccine that prevents disease but not infection caused by the bacteria.

H. pylori are believed to infect the stomach of individuals in early childhood, most likely through the oral-to-oral route from mother to child. The bacteria, found in the lining of the stomach with a small amount attached to the outer surface of the lining, can cause harmless inflammation, with about 85 per cent of infected individuals unaware they are harbouring it. But in the remaining 15 per cent, H. pylori can cause gastric lymphoma, stomach ulcers and cancer.

According to the World Health Organisation, stomach cancer is the fifth most common malignancy and the third leading cause of cancer deaths worldwide. Most people don’t know they are infected with the bacteria unless they develop stomach cancer. Meanwhile, drug resistance to H. pylori is increasing, A/Professor Sutton says.

“Increasing antibiotic resistance of H. pylori means that current treatment regimens, which already have a concerning failure rate, are likely to become increasingly less effective in the future. This leaves a looming, global public health concern where we may be unable to treat H. pylori infections,” he says.

Most H. pylori infections only produce gastritis (inflammation) but not disease, because in the majority of cases a balance is reached in the regulation of the inflammation in infected people.

 “H. pylori infection might even protect against some diseases such as oesophageal cancer and asthma,” A/Professor Sutton says. “Our discovery of a vaccine approach that can attenuate the severity of H. pylori-induced gastritis without eradicating these bacteria provides a novel approach and a new opportunity to protect individuals from the negative consequences of H. pylori infection. In particular the vaccine has the potential to protect against the development of a major global killer, stomach cancer.”

A/Professor Suttonis aiming to produce a vaccine, which his research has shown protected against the development of H. pylori gastritis in mice. The vaccine will be produced over a three-year period with the view to testing it in clinical trials. It is hoped the vaccine would eventually be delivered to school age children or young adults, well before stomach cancer develops.

HELICOBACTER PYLORI VACCINE – WHAT IS IT AND WHAT DOES IT DO?

Helicobacter pylori (H. pylori) are bacteria that infect people, most commonly during early childhood, possibly being transmitted from mother to child. These bacteria live in the mucus coating the inside of the stomach with some sticking onto the outer surface of the lining.

While there are lots of different bacteria that inhabit the gastrointestinal tract without invading it, the difference with H. pylori is that it causes an inflammatory response – gastritis. It is thought that H. pylori infection causes tight junctions between epithelial cells on the surface of the stomach, which form an impermeable barrier, to open.

This allows bits of bacteria to pass into the stomach tissues, where they can activate receptors on immune cells below the epithelial surface – a key part of the immune activation process that drives the development of gastritis. The aim of the vaccine to be produced is to block the activity of proteins produced during H. pylori infection in order to prevent the tight junctions from opening.

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