title: Adipose tissue is the first colonization site of Leptospira interrogans in subcutaneously infected hamsters.
abstract: Leptospirosis is one of the most widespread zoonoses in the world, and its most severe form in humans, "Weil's disease," may lead to jaundice, hemorrhage, renal failure, pulmonary hemorrhage syndrome, and sometimes,fatal multiple organ failure. Although the mechanisms underlying jaundice in leptospirosis have been gradually unraveled, the pathophysiology and distribution of leptospires during the early stage of infection are not well understood. Therefore, we investigated the hamster leptospirosis model, which is the accepted animal model of human Weil's disease, by using an in vivo imaging system to observe the whole bodies of animals infected with Leptospira interrogans and to identify the colonization and growth sites of the leptospires during the early phase of infection. Hamsters, infected subcutaneously with 104 bioluminescent leptospires, were analyzed by in vivo imaging, organ culture, and microscopy. The results showed that the luminescence from the leptospires spread through each hamster's body sequentially. The luminescence was first detected at the injection site only, and finally spread to the central abdomen, in the liver area. Additionally, the luminescence observed in the adipose tissue was the earliest detectable compared with the other organs, indicating that the leptospires colonized the adipose tissue at the early stage of leptospirosis. Adipose tissue cultures of the leptospires became positive earlier than the blood cultures. Microscopic analysis revealed that the leptospires colonized the inner walls of the blood vessels in the adipose tissue. In conclusion, this is the first study to report that adipose tissue is an important colonization site for leptospires, as demonstrated by microscopy and culture analyses of adipose tissue in the hamster model of Weil's disease.
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.|Division of Bacteriology, Department of Microbiology and Immunology, Faculty of Medicine, Tottori University, Tottori, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Ozuru
authors.affiliation: Department of Microbiology, University of Occupational and Environmental Health, Fukuoka, Japan.
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Saito
authors.affiliation: Morphology Core Unit, Kyushu University Hospital, Fukuoka, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kanemaru
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Miyahara
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Sharon Y A M
authors.initials: SY
authors.lastname: Villanueva
authors.affiliation: Department of Microbiology, Monash University, Melbourne, Australia.
authors.forename: Gerald L
authors.initials: GL
authors.lastname: Murray
authors.affiliation: Department of Microbiology, Monash University, Melbourne, Australia.
authors.forename: Ben
authors.initials: B
authors.lastname: Adler
authors.affiliation: Division of Bacteriology, Department of Microbiology and Immunology, Faculty of Medicine, Tottori University, Tottori, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Fujii
authors.affiliation: Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Yoshida
mesh_terms: D000273:Adipose Tissue / Q000469:parasitology*; D000818:Animals; D006224:Cricetinae; D004195:Disease Models, Animal; D005260:Female; D007921:Leptospira interrogans / Q000472:pathogenicity*; D007922:Leptospirosis / Q000469:parasitology* / Q000473:pathology*; D008163:Luminescent Measurements; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D014895:Weil Disease / Q000469:parasitology