Scientists have found the reason why older people are more likely to contract community-acquired pneumonia. The researchers found that when it comes to aging and pneumonia, one bad apple can ruin the barrel.
Lung cells that were supposed to die due to DNA damage - but didn't - were 5 to 15 times more susceptible to invasion by pneumonia-causing bacteria.
These bad apples also increased the susceptibility of normal cells around them.
Close to 1 billion adults worldwide are at risk for pneumonia. They include more than 800 million adults who are older than 65 and an estimated 210 million with chronic obstructive pulmonary disease (COPD).
Both age and COPD are associated with senescent cells, which are unable to die due to dysregulated function.
These cells have increased levels of proteins that disease-causing bacteria stick to and co-opt to invade the bloodstream. The cells also spew out molecules that increase inflammation, and make normal cells nearby do the same.
"Senescent cells prime the lungs for infection," said Pooja Shivshankar, research scientist in microbiology and immunology at the UT Health Science Center and first author on the study.
Controlling the inflammatory molecules' release could short-circuit pneumonia risk in the elderly, said the senior author, Carlos Orihuela, assistant professor of microbiology and immunology, also at the Health Science Center.
"This opens up possibilities for anti-inflammatory drugs as treatments for pneumonia," said Orihuela.
The research was published May 25 in the journal Aging Cell.