CHOP Studies Bacteria in Intestines, Link to Antibiotic Use

Published on in CHOP News

March 2, 2012 — CHOP researchers have been studying how bacteria in the intestine play important roles in regulating the immune system, with possible implications for antibiotic use. Corresponding author Junjie Mei, PhD, and senior author G. Scott Worthen, MD, both of whom are researchers in the Division of Neonatology, recently published a study in the Journal of Clinical Investigation focusing on neutrophils, white blood cells that are important components of the innate immune system.

Neutrophils are "first responders” in the immune system, attacking invading microorganisms during an acute infection. However, an excessive number of neutrophils can increase inflammation and damage tissues, so the body needs to closely regulate the quantity of neutrophils. In studying genetically engineered mice, the research team analyzed how signaling proteins, cell receptors and other biological entities interact to regulate neutrophils and keep their numbers in balance.

The researchers also found that bacteria that normally live in the gut also participate in regulating neutrophils. When the scientists treated the mice with antibiotics, those antibiotics killed gut bacteria and also reduced neutrophil levels.

“We are carrying out further studies to investigate what these effects may mean for other organs, such as the lungs,” said Worthen. “For instance, altering bacteria in the intestine may reduce how well the lungs respond to pneumonia,” he added.

Worthen cautioned against drawing too many conclusions about human biology from studies in mice, but he noted that the current findings may increase understanding of how antibiotic use in patients may harm their immune responses in specific organs.

To see the abstract of this study, click here:


John Ascenzi, Children’s Hospital of Philadelphia, 267-426-6055,