Cytokine gene expression by peripheral blood leukocytes in horses experimentally infected with Anaplasma phagocytophila.
Human granulocytic ehrlichiosis (HGE), a tick-borne zoonosis, is caused by an obligatory intragranulocytic bacterium, the HGE agent, a strain of Anaplasma phagocytophila. The equine model of HGE is considered valuable in understanding pathogenic and immune mechanisms of HGE. In the present study, cytokine mRNA expression by peripheral blood leukocytes (PBLs) in horses was examined during the course of infection by intravenous inoculation of A. phagocytophila or by allowing feeding by infected ticks. The p44 genes encoding the major outer membrane protein P44s of A. phagocytophila were detected by PCR in PBLs of all four horses from 4 to 20 days postexposure. During the 20-day infection period, interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) mRNA expression was upregulated in PBLs of all four horses, and IL-8 mRNA expression was upregulated in three horses. Gamma interferon, IL-10, and IL-12 p35 mRNAs were weakly expressed in only one horse each. IL-2, IL-4, IL-6, and IL-12 p40 mRNA expression, however, could not be detected in the PBLs of any of the four horses. These results suggest that IL-1beta, TNF-alpha, and IL-8 generation during A. phagocytophila infection has a primary role in HGE pathogenesis and immunomodulation.
Department of Veterinary Biosciences, The Ohio State University, Columbus, Ohio 43210-1093, USA.
Hyung-Yong
HY
Kim
Jason
J
Mott
Ning
N
Zhi
Tomoko
T
Tajima
Yasuko
Y
Rikihisa
D041081:Anaplasma phagocytophilum / Q000276:immunology*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D016207:Cytokines / Q000235:genetics*; D004195:Disease Models, Animal; D016873:Ehrlichiosis / Q000276:immunology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression / Q000276:immunology; D006736:Horses; D007962:Leukocytes / Q000382:microbiology* / Q000502:physiology*; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D017282:Tick-Borne Diseases / Q000276:immunology
D001425:Bacterial Outer Membrane Proteins; D016207:Cytokines; D012333:RNA, Messenger; C450839:p44 protein, Anaplasma phagocytophila