Progress 08/04/15 to 06/30/17
Outputs
Target Audience:Gastrointestinal physiologists, veterinarians, animal scientists, swine industry Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Addition of Dr. Laurianne Van Landeghem from CVM to the faculty team because of her specific knowledge of glial cells Strong collaborative team effort between the PIs and their respective labs, particularly including a post-DVM graduate student in CBS (Amanda Ziegler) as we as a new CVM faculty member from the CVM GI cluster hire: Dr. Liara Gonzalez All personnel contributed to the development of methods, assessment of results, and discussion of future steps. Amanda Ziegler was the point person for much of the experimental work How have the results been disseminated to communities of interest?This project led to a USDA-AFRI proposal entitled 'Mechanisms of Intestinal Injury in Porcine Heat Stress'. The proposal was funded as the #1 proposal by the review panel. This is a 3-year project ($494,000) in collaboration with Dr. Nicholas Gabler at Iowa State to study intestinal barrier function in swine related to the present findings. A proposal is also being submitted September 27, 2017 to NIH for an R01 "Dual Use, Dual Purpose" request for application based on this work. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Determined that mucosal recovery was significantly slower in neonates as compared to weanling pigs following ischemic intestinal injury Determined that the reduced repair response in the neonate was a result of reduced epithelial restitution (wound healing) Determined that reduced mucosal wound repair in the neonate was associated with an immature gut nerve and glial network Showed that mucosal repair could be partially restored in neonates with glial-conditioned media from glial cells grown in culture
Publications
|
Progress 10/01/15 to 09/30/16
Outputs
Target Audience:Gastrointestinal physiologists, veterinarians, and animal scientists. Changes/Problems:The major change is the addition of the glial cell component as a method to rescue intestinal repair in neonatal pigs What opportunities for training and professional development has the project provided?The project has provided advanced electrophysiological and histomorphometric training for Dr. Younggeon Jin, the post doc assigned to this project. How have the results been disseminated to communities of interest?An abstract of the work has been presented by Dr. Jin at UNC-Chapel Hill What do you plan to do during the next reporting period to accomplish the goals?We are completing the work, and have developed the working hypothesis that it is a poorly develop neural system and their accompanying cells, glial cells, that results in reduced speed of repair in neonatal pigs with ischemic intestinal injury. We are therefore conducting experiments to determine if glial cell conditioned media can speed up repair.
Impacts
What was accomplished under these goals?
Neonates have a reduced ability to repair jejunal mucosal injury as compared to juveniles in a pig model of ischemia/ reperfusion injury Our research has focused on the role of prostanoids in stimulating repair of tight junctions in juvenile pigs. However, we have identified an age-dependent disparity in the recovery of barrier function in ischemic-injured small intestine. We hypothesized that juvenile pigs would have a more rapid recovery response following ischemic injury as compared to neonates as a result of increased mucosal PGE2 levels. Neonatal pigs (1 week-of-age) and juvenile weaned pigs (6 weeks-of-age) or either sex were anesthetized, subjected to laparotomy and subjected to complete segmental ischemia of 10cm jejunal loops for 30-120 minutes. During each experiment, a neonate was paired with a juvenile pig to ensure similar conditions for both age groups. At the end of the surgical period, pigs were euthanized, and mucosal tissues were subsequently harvested from excised loops by stripping mucosa from the submucosal layer, and mounted in Ussing chambers for measurement of transepithelial electrical resistance (TER) over a 180-minute recovery period. PGE2 levels were measured from serosal chamber fluid using ELISA. Neonatal piglets failed to recover barrier function regardless of duration of ischemia as compared to juvenile pigs (6 weeks-of-age), which showed a robust recovery response following either 30 or 45 minutes of ischemia, but failed to recover with 60-120 minutes ischemia. However, contrary to our hypothesis, we noted a 1.5 - 2-fold increase in PGE2 levels in neonates following 30 or 45-minutes of ischemia as compared to juvenile pigs. Since we have previously shown that PGE2 targets ClC-2-dependent endosomal recycling of TJ proteins in repairing tissues, we propose that recovery of barrier function after intestinal I/R injury is hindered in neonates as a result of underdeveloped TJ protein recycling mechanisms. Experiments to define mechanisms of reduced mucosal repair in neonates could elucidate novel mechanisms of enhancing intestinal recovery for future clinical use. To study these mechanisms closely, we developed a porcine jejunal epithelial cell (IPEC-J2) model of intestinal barrier function in which cells subjected to 48 hours of hypoxia demonstrated a decrease followed by recovery in TER. We will identify alterations in cellular mechanisms associated with failed neonatal recovery in vivo and evaluate return of barrier function in hypoxia-injured IPEC-J2 cells in the face of inhibition or enhancement of mechanisms associated with recycling of TJ proteins in vitro. These studies will result in a greater understanding of TJ barrier injury and repair mechanisms to aid in efforts to improve return of barrier function in neonatal patients suffering from ischemic intestinal disease.
Publications
|
Progress 08/04/15 to 09/30/15
Outputs
Target Audience:Food Animal Academy, Veterinarians, Food Animal Industry, Food Safety Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? A graduate student within the CBS program, Amanda Ziegler, DVM, has gained valuable research experience as part of her PhD studies. New lectures have been taught by the PIs in CBS/PHY 764 (Advances in Gastrointestinal Pathophysiology) given in Fall 2015 to enhance teaching related to digestive diseases of animals and human beings The CALS-CVM team driving this research project has increasingly strengthened their collaboration, which is being more fully explored within the Food Animal Academy. This grant is a vital example of how this Academy could work to address important disease conditions in the food animal industry How have the results been disseminated to communities of interest? The results have been accepted as an oral presentation to be given by Dr. Amanda Ziegler at the Digestive Disease Week conference, the premier meeting for gastroenterologists throughout the world. What do you plan to do during the next reporting period to accomplish the goals? For the project, we plan to explore mechanisms responsible for reduced intestinal epithelial crawling in juvenile cells centered on a greater understanding of hypoxia inducible factor (HIF) signaling in porcine tissue and cell models Develop nutritional approaches to speeding up mucosal recovery in neonates Provide continuing education lectures to include the results of this study to industry stakeholders and animal health professionals in North Carolina using a distance education format
Impacts
What was accomplished under these goals?
We determined that piglets with ischemic intestinal injury failed to recover the intestine, whereas juvenile pigs were able to mount a vigorous intestinal recovery response A specific defect in intestinal repair in piglets was identified: the intestinal lining (epithelium) failed to crawl (restitute) to cover intestinal mucosal defects, whereas juvenile animals had evidence of rapid restitution A model of piglet intestinal epithelium using NC State IPEC-J2 cells by reducing the atmospheric oxygen (hypoxia) supplied to the cells to replicate ischemia, followed by re-oxygenation
Publications
|
|