SYDNEY, Jan. 7 (Xinhua) -- Australian researchers have discovered that a common osteoporosis treatment boosts immune cells in the lung forming one of the first lines of defense against pathogens.
The findings, released by the Garvan Institute of Medical Research on Thursday, was published in eLife. It found that bisphosphonate treatment stimulated lung macrophages to mount a stronger response against an immune challenge, which could reduce pneumonia risks.
Dr. Marcia Munoz, leading author of the paper, said previous clinical trials have suggested that bisphosphonate treatment has a beneficial effect in protecting against pneumonia, and the researchers want to understand the reasons behind it.
Bisphosphonates are a safe and effective class of osteoporosis medication that have been the standard-of-care since the 1990s to prevent loss of bone and reduce the risk of fractures.
The researchers administered a bisphosphonate called zoledronic acid to mouse models and tracked how the medication moved into different cells.
"We found that they are taken up by macrophages in the lung, which are 'first responder' cells that can recognize, engulf and destroy a pathogen during an immune response," Munoz said.
The team then tested their model's immune response by exposing them to Lipopolysaccharides (LPS), a molecule found on the surface of bacteria, which is commonly used to assess response to infection.
They found that even after just one bisphosphonate dose, the activity of macrophages in the lung had increased compared to mice that had not received the treatment.
According to researchers, in the skeleton, bisphosphonates prevent bone loss by blocking an enzyme needed by the specialized cells that break down bone. In immune cells in the lung, the researchers also found the treatment blocked the same enzyme, which in this case enhanced the immune response.
Respiratory infections, such as acute pneumonia, are a major cause of death from infection worldwide. They increasingly affect the older population, as our ability to generate protective immune responses against infectious diseases declines with age.
"Macrophages are one of the first lines of defense against infection," said senior author Professor Mike Rogers.
"If bisphosphonates are ramping up the ability of these cells to respond when they encounter a viral or bacterial infection, a stronger initial immune response may help clear the infection and lead to a better outcome. This is what we will be investigating next," he said. ■