Genetic risk factor for premature birth found

May 6, 2014, University of California - San Diego
Genetic risk factor for premature birth found
Group B Streptococcus bacteria (green) are shown binding to siglec proteins (red) that densely cover the surface of human immune cells (human cell nuclei in blue). Credit: UC San Diego School of Medicine

Researchers at the University of California, San Diego School of Medicine have discovered a genetic risk factor for premature birth. The risk factor is related to a gene that codes for a protein that the scientists have found helps the body's immune cells recognize and fight Group B Streptococcus (GBS) bacteria.

These bacteria are found in the vagina or of approximately 15 to 20 percent of healthy women, but may cause life-threatening infections, such as sepsis or meningitis in newborns, especially those born prematurely.

The study is published online in the May 5, 2014 issue of the Journal of Experimental Medicine.

"Pregnant women are universally screened for these bacteria during pregnancy and administered antibiotics intravenously during labor if they test positive to protect the infant from infection," said Victor Nizet, MD, professor of pediatrics and pharmacy and co-author. "Our research may explain why some women and their infants are at higher risk of acquiring severe GBS infections than others."

In the study, scientists identified two proteins on of the placenta that are involved in immune function. One of the proteins (known as Siglec-5) binds to the GBS pathogen and suppresses immune response to the microbe, while the other protein (known as Siglec-14) binds to the pathogen, and activates killing of the bacteria. Siglecs are found typically on . They recognize (bind) sialic acids - sugar molecules that densely coat our cells.

"We have one protein that tells the body to attack the pathogen and another that tells the body not to attack it," said Raza Ali, PhD, a project scientist in the Nizet laboratory and the study's lead author.

Scientists believe that the pair of proteins together helps balance the body's immune response to pathogens, by directing some antimicrobial response without provoking excessive inflammation.

"Identifying the dual role of these receptors and how they are regulated may provide insight for future treatments against GBS," Ali said.

Interestingly, the gene for Siglec-14 is missing in some individuals, and the researchers have found that fetuses that lack the Siglec-14 protein are at higher risk of , likely due to an imbalanced to the bacterial infection.

"We found this association in GBS-positive but not GBS-negative pregnancies, highlighting the importance of GBS-siglec crosstalk on placental membranes," said Ajit Varki, MD, Distinguished Professor of Medicine and Cellular and Molecular Medicine and study co-author.

For reasons not completely understood, GBS infections are not found in any other animals, including chimpanzees, which share 99 percent of human protein sequences. "The expression of the two siglec proteins on the fetal membranes is also unique to humans," Varki said. "Our study offers intriguing insights into why certain bacterial pathogens may produce uniquely human diseases."

The scientists believe that identifying the mechanisms of siglec protein action may help in designing therapeutic targets against bacterial infections that are becoming increasingly resistant to antibiotics and could have important implications for other disorders, such as blood clotting, chronic diseases and HIV infections.

Explore further: New survey launched into Group B streptococcus infection in babies

Related Stories

New survey launched into Group B streptococcus infection in babies

April 2, 2014
Researchers have launched a national study to see how common the potentially fatal bacterial infection Group B streptococcus is in UK and Irish babies.

More accurate diagnostic test may reduce deaths

June 26, 2012
A more accurate, faster diagnostic test for Group B Streptococcal infection in babies has been reported in the Journal of Medical Microbiology. The new test could allow better treatment and management of the disease and reduce ...

Japanese researchers identify a protein linked to the exacerbation of COPD

March 21, 2013
Researchers from the RIKEN Advanced Science Institute and Nippon Medical School in Japan have identified a protein likely to be involved in the exacerbation of chronic obstructive pulmonary disease (COPD). This protein, Siglec-14, ...

Recommended for you

Researchers identify gene responsible for mesenchymal stem cells' stem-ness'

January 22, 2018
Many doctors, researchers and patients are eager to take advantage of the promise of stem cell therapies to heal damaged tissues and replace dysfunctional cells. Hundreds of ongoing clinical trials are currently delivering ...

Genes contribute to biological motion perception and its covariation with autistic traits

January 22, 2018
Humans can readily perceive and recognize the movements of a living creature, based solely on a few point-lights tracking the motion of the major joints. Such exquisite sensitivity to biological motion (BM) signals is essential ...

Peers' genes may help friends stay in school, new study finds

January 18, 2018
While there's scientific evidence to suggest that your genes have something to do with how far you'll go in school, new research by a team from Stanford and elsewhere says the DNA of your classmates also plays a role.

Two new breast cancer genes emerge from Lynch syndrome gene study

January 18, 2018
Researchers at Columbia University Irving Medical Center and NewYork-Presbyterian have identified two new breast cancer genes. Having one of the genes—MSH6 and PMS2—approximately doubles a woman's risk of developing breast ...

A centuries-old math equation used to solve a modern-day genetics challenge

January 18, 2018
Researchers developed a new mathematical tool to validate and improve methods used by medical professionals to interpret results from clinical genetic tests. The work was published this month in Genetics in Medicine.

Can mice really mirror humans when it comes to cancer?

January 18, 2018
A new Michigan State University study is helping to answer a pressing question among scientists of just how close mice are to people when it comes to researching cancer.

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.