Scientists pinpoint key ingredient in fighting pneumonia

By Helen Dodson
Credit: Illustration by Michael Helfenbein

(Medical Xpress) -- A mysterious protein produced by a wide spectrum of living things is crucial in regulating the immune response to the most common form of pneumonia, a new Yale School of Medicine study shows. The study appears online in Cell Host & Microbe and in the July 19 print issue.

The — present in the blood of every human being – is crucial to a successful response to the bacteria and also seems to prevent that response from damaging the host, according to the researchers.

“We believe this may be a major cornerstone in our understanding how we respond to many different kinds of pathogens,” said Dr. Jack A. Elias, chair of the Department of Internal Medicine and senior author of the paper.

The Yale team investigated the protein, which has a number of names including chitinase 3-like-1 (Chi3l1), because it is a member of an ancient family of proteins found in species as diverse as plants, insects, and humans. This evolutionary conservation led researchers to believe that Chi3l1 plays an essential role in these organisms. However little was known about the functions of this protein in health or disease.  

The Yale team found that when mice lacking this key protein were exposed to Streptococcus pneumoniae, they experienced exaggerated levels of inflammation, suffered much greater damage from inflammation and hemorrhage, and had a higher rate of mortality and sepsis (blood poisoning) than those with the protein. They found that the protein helped immune system cells called macrophages to clear the pathogens from the body.

They also found that Chi311 inhibited the innate and decreased its ability to damage tissue in the host. The latter is particularly important, note the researchers, because an overwhelming innate immune system response contributes to the adverse consequences of infections, such as respiratory failure and sepsis, which are among the highest causes of death in hospitals.

“In recent years there has been a much greater appreciation that the perfect immune system response is one that eliminates bacteria but does not kill the host,” said Dr. Charles Dela Cruz, assistant professor of medicine and lead author of the paper. “This molecule seems to help the organism achieve that balance.”

Related Stories

Recommended for you

A high-fat diet may alleviate mitochondrial disease

date 3 hours ago

Mice that have a genetic version of mitochondrial disease can easily be mistaken for much older animals by the time they are nine months old: they have thinning grey hair, osteoporosis, poor hearing, infertility, ...

Cheek muscles hold up better than leg muscles in space

date 3 hours ago

It is well known that muscles need resistance (gravity) to maintain optimal health, and when they do not have this resistance, they deteriorate. A new report published in the July 2015 issue of The FASEB Journal, however, sugges ...

Sialic acid: A key to unlocking brain disorders

date 6 hours ago

A new report published in the July 2015 issue of The FASEB Journal suggests that a common molecule found in higher animals, including humans, affects brain structure. This molecule may play a significant role in how brain ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.