The Hunter laboratory studies the pathophysiology of necrotizing enterocolitis (NEC) and other intestinal disorders that affect children such as inflammatory bowel disease (IBD). Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of newborns and affects 5-10% of all infants in the neonatal intensive care unit. Prematurity, formula feeding and abnormal patterns of microbial colonization are established risk factors. Current treatment approaches are limited to bowel rest, antibiotics, and in severe cases surgical resection of necrotic bowel. The nonspecific nature of these therapies reflect the fact that NEC pathogenesis is, essentially, undefined. Delineation of the processes responsible for NEC is, therefore, a high priority and prerequisite to developing meaningful medical interventions to prevent or treat NEC. The main objects of our research are to better understand the complex mechanisms that cause some babies and children to be susceptible to these diseases, and identify potential cures and preventative strategies.
Current research projects
Defining the role of protein kinase A in the pathogenesis of intestinal disorders of childhood
Protein kinase A is an important mediator and is involved in multiple important cellular functions including inflammation and cell death. An increase in intestinal inflammation, injury and epithelial death are characteristic of NEC and IBD. In order to identify key players in the development of disease we use a multi modal approach including cell lines and human tissue samples. We have also engineered 3-dimensional models of infant intestine to work with in the laboratory, allowing us to make key insights into the pathophysiology of human disease. Using these approaches we identified that protein kinase A is activated during human NEC. Excitingly we have demonstrated that blocking the activation of this protein kinase is protective against intestinal injury and NEC in the laboratory demonstrating a potential therapeutic strategy.
ROCK, Tight junctions and NEC
Rho kinases (ROCK) are serine/ threonine kinases and are involved in multiple cellular processes including regulating tight junction function, actin cytoskeleton contraction, inflammatory cytokines and cell death. Tight junctions are protein complexes that regulate the connections between cells maintaining normal permeability and intestinal integrity. We have previously demonstrated the importance of these pathways to the pathophysiology of NEC. The objectives of this project are to define mechanisms of ROCK activation, identify molecular pathways targeted by ROCK during experimental NEC and to determine how ROCK inhibition limits NEC progression. The central hypothesis NEC is associated with ROCK activation, resulting in tight junction breakdown that enhances mucosal and systemic inflammation and epithelial cell death. If this hypothesis is correct then ROCK inhibition will be protective against these effects and NEC. These findings will have a significant positive impact on human health by providing a new understanding of the mechanisms governing epithelial intestinal barrier function during NEC.
MicroRNAs and NEC
MicroRNAs (miRNAs) are short non-coding RNAs that are key modulators in various cellular processes at the post-transcriptional level. Aberrant expression of specific miRNAs have been identified in many pathological conditions including cancers, neurodevelopmental disorders, cardiovascular and inflammatory diseases. Unique miRNA expression profiles have been reported in the intestinal epithelial cells of patients with inflammatory bowel disease (IBD) as well as in the peripheral blood of patients with active IBD. The role of miRNAs in NEC has not yet been studied. The objective of this project is to identify miRNAs with aberrant expression in NEC allowing for their use as biomarkers of clinical disease. Successful completion of this project will provide insight into the role of miRNAs in the pathophysiology of NEC. This will be pivotal in the development of diagnostic miRNA biomarkers as well as targeted therapies for the prevention and treatment of NEC.
Doug Wood, BS. Research Technician Carrie Yuan, BS. Research Technician Samuel Klonoski, MD. Research Fellow Emily Winterhalter, Undergraduate Student John Sincavage, Medical Student Robin Redline, Research Technician II
Blackwood B, Wood DR, Yuan CY, Nicolas JD, Griffiths A, Mestan K, Hunter CJ. Urinary Claudin-2 measurements as a predictor of necrotizing enterocolitis. Journal of Neonatal Surgery. October 2015. PMID: 26500853
Blackwood BP, Wood DR, Yuan C, Nicolas J, De Plaen IG, Farrow KN, Chou P, Turner JR, Hunter CJ. A role for cAMP and PKA in experimental necrotizing enterocolitis. American Journal of Pathology. Dec 2016. PMID: 27939131.
Blackwood, BP, Hunter CJ, Grabowski J. Variability in Antibiotic Regimes for Surgical NEC Highlights the Need for New Guidelines. Surgical Infections. Jan 2017. PMID: 28048964.
Blackwood BP, Yuan CY, Wood DR, Nicola JD, Grothaus JS, Hunter CJ. Probiotic Lactobacillus species strengthen intestinal barrier function and tight junction integrity in experimental necrotizing enterocolitis. Journal of Probiotics and Health. Jan 2017. PMID: 28638850.
Grothaus J, Ares G, Yuan C, Wood D, Hunter CJ. Rho Kinase Inhibition Maintains Intestinal and Vascular Barrier Function by Upregulation of Occludin in Experimental Necrotizing Enterocolitis. American Journal of Physiology – Gastrointestinal and Liver Physiology. June 2018. PMID: 29927318.