New research has shown that a lack of dietary zinc can boost the chances of a lung infection caused by Acinetobacter baumannii bacteria; these pathogens are a major reason why people on ventilators get sick with pneumonia. This study has found a connection between molecules that promote inflammation and A. baumannii infections. When that connection was blocked, the severity of pneumonia in a mouse model was reduced dramatically. The findings have been reported in Nature Microbiology.
It's estimated that about one-fifth of the global population are zinc deficient. This deficiency can disrupt the function of the immune system and raise the risk of pneumonia. Zinc deficiency is suspected to be a leading contributor to disease and mortality, according to The World Health Organization.
Elderly patients who are being treated in healthcare settings are at high risk of pneumonia infection, as well as zinc deficiency. Healthcare devices like catheters or ventilators can cause infections, many of which are resistant to drug treatment. This includes A. baumannii, which is growing more resistant to antimicrobial drugs.
In this study, the researchers examined a mouse model of zinc deficiency that was affected by A. baumannii pneumonia. These mice were found to generate unusually high levels of an inflammatory cytokine called interleukin-13 (IL-13) during infection. When mice carrying sufficient levels of zinc were also exposed to IL-13, their A. baumannii lung infection spread to the spleen.
Additional work showed that when the mice were treated with an antibody that blocked the effects of IL-13, they were protected from death that can be caused by A. baumannii infections.
The investigators noted that IL-13 antibodies (lebrikizumab and tralokinumab) have already been approved for use in patients with severe asthma by the US Food and Drug Administration. Although those drugs were not effective in that application, they could improve outcomes for patients with bacterial pneumonia.
“To our knowledge, this is the first study showing that neutralization of IL-13 could prevent mortality from a bacterial infection,” said corresponding study author Eric Skaar, PhD, MPH, a Professor of Pathology and director of the Vanderbilt Institute for Infection, Immunology and Inflammation. “This discovery points to the possibility of using anti-IL-13 therapy in patients with zinc deficiency and A. baumannii pneumonia as part of a personalized therapy approach.”
This work adds to other recent evidence indicating that nutrient deficiencies can affect immune responses.
Sources: Vanderbilt University, Nature Microbiology