Location: Food and Feed Safety Research
Title: Critical role of glycogen synthase kinase-3ß in regulating the avian heterophil response to Salmonella enterica serovar Enteritidis Authors
|Chiang, Hsin -|
|Zhou, Huaijun -|
Submitted to: Frontiers in Veterinary Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 9, 2014
Publication Date: N/A
Interpretive Summary: There is a great deal of controversy concerning the use of antibiotics in animal feed. The biggest problem that critics have with this practice is the growing number of antibiotic-resistant bacteria that are causing disease in humans. These bacteria appear to come from meat products. Therefore, we are interested in identifying chemicals that can protect animals from bacterial contamination without causing the bacteria to be resistant to antibiotics and other drugs that are used to treat human diseases. The purpose of these experiments was to see what kind of chemicals are produced by the immune cells when they see bacteria. We found that the immune cells produce two different chemicals that control a host response and kill the bacteria before they can hurt the chick. The results of this experiment are important to the pharmaceutical industry in the United States because we now know which chemicals are produced (or not) by the baby chick’s cells of the immune system when they see Salmonella. Thus, we can now see if there are ways for us to get the baby chick to make these chemicals which will help the chick fight Salmonella infections.
Technical Abstract: A microarray-assisted gene expression screen of chicken heterophils revealed glycogen synthase kinase-3ß (GSK-3ß), a multifunctional Ser/Thr kinase, to be consistently up-regulated 30-180 min following stimulation with Salmonella enterica serovar Enteritidis (S. Enteritidis). The present study was designed to delineate the role of GSK-3ß in regulating the innate function of chicken heterophils in response to S. Enteritidis exposure. Using a specific GSK-3ß ELISA assay 30 min after infection with S. Enteritidis heterophils had a significant decrease in total GSK-3ß, but a significant increase in phosphorylated GSK-3ß (Ser9). By 60 min post-infection, there was no difference in the amount of phosphorylated GSK-3ß (Ser9) in either the uninfected or infected heterophils. S. Enteritidis interaction with heterophils alters GSK-3ß activity by stimulating phosphorylation at Ser9 and that peaks by 30 min post-infection. Further, inhibition of GSK3ß with lithium chloride resulted in a significant decrease in NF-'B activation and expression of IL-6, but induces a significant increase in the expression of the anti-inflammatory cytokine, IL-10. Using a phospho-specific antibody array confirmed the phosphorylation of GSK-3ß (Ser9) as well as the phosphorylation of the downstream cytokine-activated intracellular signaling pathway involved in stimulating immune responses, I'B, the I'B subunit IKK-ß, and the NF-'B subunits p105, p65, and c-Rel. Our data revealed that the phosphorylation of GSK-3ß (Ser9) is responsible for inducing and controlling an innate response to the bacteria. Our findings suggest that the repression of GSK-3 activity is beneficial to the host cell and may act as a target for treatment in controlling intestinal colonization in chickens. Further experiments will define the in vivo modulation of GSK-3 as a potential alternative to antibiotics in salmonella and other intestinal bacterial infections.