Statins can reduce the risk of severe bacterial infections such as pneumonia and sepsis with their cholesterol-lowering properties.
Researchers at the University of California, San Diego School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences, found that phagocytes (white blood cells that kill and ingest harmful bacteria, foreign particles and dead or dying cells) became more effective after being exposed to statins.
Victor Nizet, professor of pediatrics and pharmacy, and Christopher Glass, professor of medicine and cellular and molecular medicine, the UC San Diego team, led the study.
The researchers also found that statins stimulated the phagocytes to release "extracellular traps" - specialized webs of DNA-based filaments embedded with anti-microbial peptides and enzymes capable of ensnaring and killing bacteria before they spread in the body.
Glass said that the findings have broad ramifications given the popularity of statins for controlling high cholesterol levels.
"Clinical research indicates that perhaps 100 million Americans have elevated cholesterol levels that could benefit from statin therapy. Thus any statin-associated changes to immune system function are certain to impact millions of people," said Glass.
Prior research had described various anti-inflammatory properties of statins, suggesting that these effects could contribute to a reduction in disease severity during severe infections.
The UCSD findings demonstrate that statins have important pharmacological effects beyond inhibiting cholesterol production.
"We found these drugs fundamentally alter how white blood cells behave upon encountering bacteria. In our studies with staph bacteria, the net effect of statin treatment was to improve bacterial killing and extracellular trap formation. These same changes might not be so consequential for defense against less virulent bacteria that are easily susceptible to uptake and killing within phagocytes," said Nizet.
The research also sheds important new light on the clinical phenomenon of reduced infection severity in patients receiving statins, the scientists said. It indicates that levels of cholesterol or related lipid molecules can be sensed by white blood cells and used as signals to control their inflammatory and antibacterial activities.
The research is published in the issue of Cell Host and Microbe.