Scientists pinpoint key ingredient in fighting pneumonia

July 19, 2012 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.”

Explore further: Researchers find chemical signals that initiate the body's immune response

Related Stories

When body clock runs down, immune system takes time off

February 16, 2012

It's been said that timing is everything, and that may be particularly true when it comes to the ability to fight off disease. New research published by Cell Press in the February issue of the journal Immunity shows that ...

Recommended for you

Synthetic 3D-printed material helps bones regrow

September 28, 2016

A cheap and easy to make synthetic bone material has been shown to stimulate new bone growth when implanted in the spines of rats and a monkey's skull, researchers said Wednesday.

Epigenetic clock predicts life expectancy

September 28, 2016

UCLA geneticist Steve Horvath led a team of 65 scientists in seven countries to record age-related changes to human DNA, calculate biological age and estimate a person's lifespan. A higher biological age—regardless of chronological ...

Engineered blood vessels grow in lambs

September 27, 2016

In a hopeful development for children born with congenital heart defects, scientists said Tuesday they had built artificial blood vessels which grew unaided when implanted into lambs, right into adulthood.

Fighting the aging process at a cellular level

September 22, 2016

It was about 400 BC when Hippocrates astutely observed that gluttony and early death seemed to go hand in hand. Too much food appeared to 'extinguish' life in much the same way as putting too much wood on a fire smothers ...

0 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.