University of Kentucky UKnowledge Theses and Dissertations--Veterinary Science Veterinary Science 2012 RHODOCOCCUS EQUI INFECTION AND INTERFERON-GAMMA REGULATION IN FOALS Lingshuang Sun University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Sun, Lingshuang, "RHODOCOCCUS EQUI INFECTION AND INTERFERON-GAMMA REGULATION IN FOALS" (2012). Theses and Dissertations--Veterinary Science. 7. https://uknowledge.uky.edu/gluck_etds/7 This Doctoral Dissertation is brought to you for free and open access by the Veterinary Science at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Veterinary Science by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained and attached hereto needed written permission statements(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine). I hereby grant to The University of Kentucky and its agents the non-exclusive license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known. I agree that the document mentioned above may be made available immediately for worldwide access unless a preapproved embargo applies. I retain all other ownership rights to the copyright of my work. I also retain the right to use in future works (such as articles or books) all or part of my work. I understand that I am free to register the copyright to my work. REVIEW, APPROVAL AND ACCEPTANCE The document mentioned above has been reviewed and accepted by the student’s advisor, on behalf of the advisory committee, and by the Director of Graduate Studies (DGS), on behalf of the program; we verify that this is the final, approved version of the student’s dissertation including all changes required by the advisory committee. The undersigned agree to abide by the statements above. Lingshuang Sun, Student Dr. David W. Horohov, Major Professor Dr. Daniel K. Howe, Director of Graduate Studies RHODOCOCCUS EQUI INFECTION AND INTERFERON-GAMMA REGULATION IN FOALS DISSERTATION A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Agriculture at the University of Kentucky By Lingshuang Sun Lexington, Kentucky Director: Dr. David W. Horohov, Professor of Immunology Lexington, Kentucky 2012 Copyright © Lingshuang Sun 2012 ABSTRACT OF DISSERTATION RHODOCOCCUS EQUI INFECTION AND INTERFERON-GAMMA REGULATION IN FOALS Rhodococcus equi (R. equi) is one of the most serious causes of pneumonia in young foals. The clinical disease is of great concern to breeding farms worldwide due to the impact of mortality on economic losses. While adult horses are resistant to R. equi, foals exhibit a distinct age-associated susceptibility. The mechanism underlying this susceptibility in foals is not well understood. Interferon-gamma (IFNplays an important role in the clearance of R. equi, but its expression is impaired in neonatal foals. Moreover, the regulation of this age-related IFN expression in foals remains unknown. In humans, IFN expression has been shown to be regulated by DNA methylation, lymphoproliferation, and influenced by environmental exposure. Therefore, we hypothesized that environmental exposure promotes IFN expression through regulation of DNA methylation and lymphoproliferation. The objectives were: (1) to estimate the relevance of IFN- production and R. equi infection in foals; (2) investigate the role of lymphoproliferation and DNA methylation in the regulation of IFN- expression in foals; (3) to evaluate the effect of environmental exposure on IFN- expression by housing foals in a barn environment verses pasture.; (4) to investigate the effect of environment exposure on antigen-presenting cells (APC), which sensor the environmental antigens and modulate IFN- production by T cells. The results demonstrated that the IFN- expression was inversely correlated with the age-related susceptibility to R. equi infection. lymphoproliferation promoted IFN- expression in foals, whereas, DNA methylation repressed IFN- expression. The IFN- expression was augmented in foals exposed to the barn air which contained higher numbers of aerosol miroorganisms. DNA on the IFN- promoter was demethylated and the lymphoproliferative activity was elevated in foals with barn-air exposure. The barn-air exposure also promoted the maturation and activation of APC to prime IFN- expression by T cells in foals. Overall, this body of work demenstrated a relationship between IFN- expression and R. equi infection, provided novel information on mechanisms that regulate IFN- expression, and identified the effect of environment on mechanisms responsible for IFN- expression. KEY WORDS: Foal, Interferon-gamma, Regulation, Rhodococcus equi, Environment Lingshuang Sun December 12, 2012 RHODOCOCCUS EQUI INFECTION AND INTERFERON-GAMMA REGULATION IN FOALS By Lingshuang Sun David W. Horohov Director of Dissertation Daniel Howe Director of Graduate Studies December 12, 2012 This doctoral dissertation is dedicated to my beloved family members: Father Chengsong Sun Mother Shaohua Xu Sister Lingyun Sun & Yuanyuan Sun Brother Yunce Sun ACKNOWLEDGMENTS The completion of my doctorate would not have been possible without the support, patience and guidance of many people that I have met and worked with during my graduate studies. It is a pleasure to convey my gratitude to everyone in my humble acknowledgment. I owe my deepest gratefulness to Dr. Dvid W. Horohov for his advice, direction, and generous support throughout my studies. He opened the doors for me to join the program and care for me the entire time. His way of scientific thinking and teaching inspired me and enriched my growth as a student, a researcher and a scientist. I am indebted for all his contributions of time and ideas which helped to make my graduate experience productive and stimulating. I sincerely appreciate the years spent under his guidance. I would like to convey my sincere gratitude to my other Ph.D dissertation committee members, Drs. Frank Cook, Thomas Chambers, Don Cohen, and the outside examiner, Dr. James Bryson, for their time, insightful questions and valuable discussions during my exam as well as the committee meetings. Without the support of Dr. Cohen, the APC projects would not have been completed. Thank you to all my collaborators: Dr. Alan T. Loynachan (LDDC, University of Kentucky) for all the pathological work on R. euqi study, Zhangbin Gong (Shanghai University of Traditional Chinese Medicine) for contribution to the DNA methylation project. I also appreciate the support received from all of our lab members. Particularly, I am indebted to Dr. Amanda A. Adams for her guidance and scientific contribution. Without her valuable organization, I could not have completed the environmental project. iii I would also like to thank Drs. Catherine Merant, Tracy Sturgill, and Cormac Breathnach for their leading and training. The appreciation would also address to Dr. Allen Page for his work on almost all the BAL. I am grateful to our technicians, especially Alejandra Betancourt. I am indebt to her for her always willing to help and wonderful management of the lab. I would also like to thank the great help I got from our undergraduate student, especially Eric J. Oberst and John Craig Stewart. It was an honor to work with Macarina Sanz and Chong Liu. Everyone was great! I gratefully appreciate the farm crew for their great job on taking care of the foals. In particular, I would like to thank Lynn and Kevin for their organization and management of the farm crew. I would also appreciate John Allen and Millard Stamper for their taking care of the pony foals, without them the environmental study wouldn’t complete. The appreciation is also sent to all the foals for their contribution to the studies. I would like to thank Dr. Daniel Howe for his support as the Director of Graduate Studies. I appreciate all the faculty and staff in the department, particularly to the members of Drs. Macleod, Chambers, Timoney, Balasuriya, and Troedesson’s laboratories for allowing me use their equipment and instructing me on how to operate everything. I would like to extend my appreciation to all the graduate students in Gluck for their help and company. Special appreciation would like to address to Stevephen, Debi Even, Elizabeth Woodward and Ablesh Gautam for their work as a representative of our department and their organization of graduate activities. All this made my life colorful. I would also like to thank all of the administrative staff in the Department of Veterinary Science, especially Diane Furry, Patsy Garrett, Roy Leach, Debbie Mollet, iv and Gail Watkins who were always ready to help and made being a graduate student in the department pleasant. I gratefully acknowledge the funding sources that made my Ph.D. work possible: Bioniche Life Science Inc.,William Robert Mills Endowment and United States Department of Agriculture. The Wright Markey Trust Fund is greatly acknowledged for providing my personal financial stipend. Last, but not the least, I would like