ACE Inhibitors Reduce Immune Defence against Bacteria

Neutrophil interacting with two pink-colored, rod shaped, multidrug-resistant (MDR), Klebsiella pneumoniae
Neutrophil interacting with two pink-colored, rod shaped, multidrug-resistant (MDR), Klebsiella pneumoniae. Photo by CDC on Unsplash

Scientists have found evidence suggesting that giving patients ACE inhibitors reduces the ability of their immune system to resist bacterial infections.  the group describes testing of multiple ACE inhibitors in mice and human cells.

ACE inhibitors are typically given to patients with hypertension, and some instances to people with heart failure, kidney disease or diabetes. The drugs relaxes the walls of arteries, veins and capillaries, reducing blood pressure. Some prior studies had shown that the drugs also help the immune system by boosting neutrophils, which are produced to fight bacteria. In this new study, published in the journal Science Translational Medicine, the researchers have found the opposite to be true.

In order to see the effects of ACE inhibitors on the immune system, researchers at Cedars-Sinai Medical Center administered different brands of ACE inhibitor such as Zestril and Altace, to mice and then tested their ability to resist bacterial infections. Compared to untreated mice, those with the ACE inhibitors had greater difficulty in recovering from bacterial infections such as staph.

Seven human patients who were taking an ACE inhibitor volunteered blood samples to measure their immune response. The researchers found that the neutrophils were unable to produce the molecules needed to fight off bacteria. They were also found to be in vitro ineffective against bacteria.

The researchers also tested another drug used to treat hypertension, an angiotensin II receptor drug, Cozaar. These drugs work by preventing arterial walls from constricting, which reduces blood pressure. They found no evidence of a negative impact on immunity. They did not test beta-blockers, which work by preventing adrenergic receptors from being stimulated, reducing cardiac action.

The researchers concluded that administering ACE inhibitors to patients puts them at an increased risk of bacterial infections, noting that doctors may want to try alternative drugs to treat their patients.

Source: MedicalXpress

Journal information: Duo-Yao Cao et al, An ACE inhibitor reduces bactericidal activity of human neutrophils in vitro and impairs mouse neutrophil activity in vivo, Science Translational Medicine (2021). DOI: 10.1126/scitranslmed.abj2138

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