By Andy Coghlan
Already hailed as a wonder drug, the humble aspirin might also combat viruses that attack fetuses and patients with damaged immunity.
Aspirin was originally developed to numb pain. But it also helps prevent heart attacks and strokes by inhibiting blood clot formation, and even shrinks polyps that otherwise develop into colon cancer. Now, Thomas Shenk and his team at Princeton University in New Jersey have shown that close relatives of aspirin can block common viruses.
“For a 100-year-old drug, aspirin never stops springing surprises,” says Nick Henderson of the charity European Aspirin Foundation. “Every year, aspirin re-invents itself.”
Human cytomegaloviruses (CMV) are members of the family that cause cold sores and herpes infections. They are present in one tenth of the population, and usually pose no threat. But CMV can cause hearing problems in babies born to infected mothers and kill patients with reduced immunity, such as those with AIDS or transplant recipients taking anti-rejection drugs.
Shenk and his colleagues have now shown that aspirin-like drugs can stop CMV from replicating in infected cells.
The drugs do this by blocking production of cyclooxygenase 2, an enzyme better known as COX-2. Normally, COX-2 helps to manufacture prostaglandin E2, a chemical that triggers fever and inflammation. But prostaglandin E2 can be commandeered by viruses to help them multiply.
Shenk showed that fibroblasts (taken from human foreskins) infected with CMV made 50 times more prostaglandin E2 than normal. But the cells stopped making E2 altogether as soon as they were exposed to the aspirin-like drugs. At the same time, virus production by the cells dropped 100-fold.
The amount of virus increased again when Shenk and his colleagues dunked the cells in prostaglandin E2. Reliance on this “outside supply” proved that the drugs worked by blocking prostaglandin within the cells.
Shenk believes that at low doses, aspirin-like drugs might have preventative benefits for pregnant women and patients with reduced immunity. “Lower concentrations might prove to be therapeutically beneficial,” he says.
Further work is needed to reveal whether aspirin-type drugs could be effective against other viruses.
Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.052713799)