A new study finds that sulfasalazine, a drug used to treat inflammation, is effective at reducing the level of infection of Pneumocystis pneumonia (PCP) caused by the fungus Pneumocystis jirovecii, which is especially deadly for AIDS and cancer patients and others with weakened immune systems. The findings have been published in the journal PLoS Pathogens.

The lungs of sufferers of Pneumocystis become a battlefield, when attacked by the fungal microbes. Even when the body gets the upper hand, the damage is tremendous. Immune cells like neutrophils and macrophages can flood the lungs, suffocating the patient. In addition, when the debris from dead microbes fills the lungs, more and more immune cells are called in to clean up the area, making matters worse, and making it harder for the patient to breathe.

“Many people assume that once the microbe is dead, patients usually start to feel better immediately. But with Pneumocystis, patients do not always undergo a rapid clinical improvement following antibiotic treatment. Even though the bug has been killed, the debris that is left in the lungs continues to promote inflammation,” said Terry Wright, PhD, an infectious disease specialist and associate professor of microbiology and immunology and pediatrics at the University of Rochester, NY.

Pneumocystis is a common bug that infects nearly everyone at some point. Most people recover from the infection without consequence, but for people with cancer, AIDS, or other diseases that compromise their immune system, the infection can be deadly. Usually there are few signs that the patient is sick until the infection is well established and the fungus is widespread in the lungs. Among cancer patients, mortality rates as high as 40% have been reported.

Doctors use two different drugs in tandem to treat patients—an antibiotic to kill the bug, and steroids or another type of drug to reduce the consequent inflammation.

The study looked at the effects in mice of sulfasalazine, which has proven useful in treating conditions like Crohn’s disease and rheumatoid arthritis. The researchers found that Pneumocystis-infected mice treated with sulfasalazine developed much less severe disease than untreated mice. The sulfasalazine-treated mice had better lung function, less weight loss, and were generally healthier than untreated animals.

While some of the benefit was due to the drug’s anti-inflammatory properties and was expected, the result included a surprise—it also spurs the body to remove the bug more aggressively by boosting the activity of immune cells called macrophages.

Source: University of Rochester Medical Center