This is a K01 application from NIDDK in the field of Clostridium difficile infection (CDI). My long- term career objective is to utilize knowledge acquired through my work and others to develop measures of prevention and therapy against CDI and other enteric pathogens-associated diseases. The object of this study is to elucidate the signaling pathway of C. difficile toxin- mediated TNF-? production and develop a novel therapy against CDI by targeted blocking TNF- ? production.
Three specific aims will be pursued.
Specific Aim 1 : Identify subsets of immune cells that are major producer of TNF-? in response to C. difficile toxins in vivo, based on our hypothesis that intestinal dendritic cells (DCs) and macrophages are major TNF-? producer during the bacterial infection.
Specific Aim 2 : Investigate the signaling events that lead to toxin-mediated TNF-? production in macrophages.
Specific Aim 3 : Evaluate blocking TNF-? production as an adjunctive therapy against intestinal inflammation in both primary and recurrent CDI.
For specific aim1, TNF-? producing immune cells will be identified by immuofluorescence staining and immunohistochemistry in mouse ileal loop model and C. difficile infection in mice. To more precisely assess the roles of DCs and macrophages in TNF-? production, DC- or macrophage- depleted mice will be used.
For specific aim 2, multiple approaches including siRNA knockdown, Western-blot analysis, RT-PCR will be performed to identify the involvement of small Rho GTPases and dual specificity phosphatases (DUSPs) in C. difficile toxin-induced TNF-? production.
In specific aim 3, a novel glucan particle (GP)- dependent siRNA delivery system specifically targeting macrophages and DCs will be employed to evaluate blocking TNF-? production as an adjunctive therapy against intestinal inflammation in CDI.

Public Health Relevance

This K01 project is designed to find out novel therapeutic targets and to test a novel treatment approach to reduce severity of inflammation in a mouse model of primary and recurrent Clostridium difficile infection.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Scientist Development Award - Research & Training (K01)
Project #
5K01DK092352-03
Application #
8637068
Study Section
Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Podskalny, Judith M,
Project Start
2012-04-01
Project End
2017-03-31
Budget Start
2014-04-01
Budget End
2015-03-31
Support Year
3
Fiscal Year
2014
Total Cost
$93,925
Indirect Cost
$6,957
Name
Tufts University
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
039318308
City
Boston
State
MA
Country
United States
Zip Code
02111
Sun, Xingmin; Hirota, Simon A (2015) The roles of host and pathogen factors and the innate immune response in the pathogenesis of Clostridium difficile infection. Mol Immunol 63:193-202
Kim, Hyeun Bum; Zhang, Quanshun; Sun, Xingmin et al. (2014) Beneficial effect of oral tigecycline treatment on Clostridium difficile infection in gnotobiotic piglets. Antimicrob Agents Chemother 58:7560-4