A gene that codes for a protein that scientists have found helps the body’s immune cells recognize and fight Group B Streptococcus (GBS) bacteria has been implicated in premature birth risk.
The bacteria are found in the vagina or lower gastrointestinal tract 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.
In the study, the scientists identified two proteins on fetal membranes 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 cell surface receptors found typically on immune cells. They recognize (bind) sialic acids - sugar molecules that densely coat our cells.
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
“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.”
“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 premature birth, likely due to an imbalanced immune response 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.
Co-authors include Jerry J. Fong, Aaron F. Carlin, Rebecka Linden, Mana Parast, UC San Diego; Tamara Busch and Jeffrey Murray, University of Iowa; Takashi Angata, Academia Sinica, Taiwan and Thomas Areschoug, Lund University, Sweden.
Published in the Journal of Experimental Medicine.
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Sexual Fantasies: Threesomes Are Normal, Golden Showers Not So Much
- Ghost Light From Dead Galaxies - A Hubble Halloween
- US Wildlife Bans On GMOs And Neonics Lack Transparency And Scientific Rationale
- Is It Possible To Build A Spacesuit Or Spaceship To Travel Through The Sun With Future Tech? - Just For Fun.
- Does Max Tegmark Kill A Daughter In A Parallel World ?
- The Way Architecture Imitates Life, Biology Meets Geometry
- Greenpeace Says Its GMOs Are Better Than Science's GMOs, Still Hates Golden Rice
- "Verduyn is right on the money when he says it's not the emotion of sadness itself that's inherently..."
- "A very astute observation, given that they're both, in essence, electrical phenomena...."
- "A growing population is a huge problem because we take for granted the innovations that have..."
- " Well, perhaps, my inference and reply is faulty, but you do say Tolle basically claims his way..."
- "I'm flattered you think I wrote this. Jon will be less pleased...."
- Two-faced anti-GMO groups: Block crop and food innovations then claim Big Ag prevents GMO innovations
- Why support erodes for GMO labeling (Hint: It’s not because of spending by Big Ag)
- Genetic “hall of mirrors” with large palindromes, yet smaller: What’s mighty about the mouse
- Gut bacteria an easy scapegoat for disease, but connections hard to prove
- Vermont Rube Goldberg-like GMO labeling law exempts GMO filled natural supplements
- Downside to GMOs: Yields have become so good, they exceed processing capacity
- Fun and games make for better learners
- Avivagen publishes evidence for natural alternative to antibiotic use in livestock
- Drug tests on mothers' hair links recreational drug use to birth defects
- Bladderwrack: Tougher than suspected
- Scientists seek cure for devastating witches' broom disease of the chocolate tree
Books By Writers Here