Department of Internal Medicine
Jacob IJdo, M.D., Ph.D.
Director, Rheumatology Fellowship Program
Current Research Interests focus on the interaction of neutrophils with Anaplasma phagocytophilum. A. phagocytophilum (formerly Ehrlichia equi or Ehrlichia phagocytophilum) is unique because it is the only human pathogen that survives and replicates exclusively in neutrophils. Neutrophils are a major player in the innate immune system. Thus, A. phagocytophilum infection can be used as a model to study the innate immune system and in particular neutrophil biology and neutrophil-bacterial interactions. A. phagocytophilum manipulates the host cell in several ways: 1) it inhibits the accumulation of NADPH oxidase at the A. phagocytophilum phagosomes, preventing killing of the bacteria by reactive oxygen species (ROS), 2) it inhibits the fusion of lysosomes with phagosomes containing A. phagocytophilum, preventing destruction by lysosomal enzymes, and 3) it delays neutrophil apoptosis, which may be critically important for a prolonged intracellular stay as the normal life span of peripheral neutrophils is only 18-24 hours. The molecular mechanisms for these observed cellular changes are not known, but we have recently identified a virulence factor, AnkA, that is translocated by a type four secretion system (T4SS). Early during infection AnkA undergoes tyrosine phosphorylation, which facilitates the interaction with SH2 domains of host signaling proteins. We are now investigating the signaling pathways that are altered by AnkA leading to A. phagocytophilum survival in neutrophils.
Dr. IJdo became the Rheumatology Fellowship Program Director in 2008.
Honors, Awards, and Organizations
- American College of Rheumatology
- American Society of Rickettsiology
- Daland Research Fellowship Award, American Philosophical Society 1996-1998
- Physician-Scientist Fellowship Award, Lucille P. Markey Charitable Trust 1997-1999
- Robert Leet and Clara Guthrie Patterson Trust Award, 2000
- Scientist Development Award, American Heart Association, 2004-2007
- IJdo JW, Carlson AC, Kennedy EL. Anaplasma phagocytophilum AnkA is tyrosine phosphorylated at EPIYA motifs and recruits SHP-1 during early infection. Cell Microbiol. 2007 May;9(5):1284-96. Epub 2007 Jan 22.
- Rainwater KK, IJdo JW, Capuano A, Gilchrist MJ, Gill JS. Serosurveillance for Anaplasma phagocytophilum antibodies in white-tailed deer (Odocoileus virginianus) in Iowa, USA.
Vector Borne Zoonotic Dis. 2006. 6(3):275-82.
- IJdo JW, Mueller AC. Neutrophil NADPH oxidase is reduced at the Anaplasma phagocytophilum phagosome. Infect. Immun. 72(9):5392-401, 2004