The rise in asthma over the past decades, Dr. Blaser says, could stem from the fact that a stomach harboring H. pylori has a different immunological status from one lacking the bug. When H. pylori is present, the stomach is lined with immune cells called regulatory T cells that control the body's response to invaders. Without these cells, a child can be more sensitive to allergens.
"Our hypothesis is that if you have Helicobacter you have a greater population of regulatory T-cells that are setting a higher threshold for sensitization," Dr. Blaser explains. "For example, if a child doesn't have Helicobacter and has contact with two or three cockroaches, he may get sensitized to them. But if Helicobacter is directing the immune response, then even if a child comes into contact with many cockroaches he may not get sensitized because his immune system is more tolerant."
In other words, the presence of the bacteria in the stomach may influence how a child's immune system develops: if a child does not encounter Helicobacter early on, the immune system may not learn how to regulate a response to allergens. Therefore, the child may be more likely to mount the kinds of inflammatory responses that trigger asthma.
"There's a growing body of data that says that early life use of antibiotics increases risk of asthma, and parents and doctors are using antibiotics like water," Dr. Blaser says. "The reality is that Helicobacte
Contact: Lorinda Klein
NYU Langone Medical Center / New York University School of Medicine