›› 2011, Vol. 31 ›› Issue (5): 527-.doi: 10.3969/j.issn.1674-8115.2011.05.001

• Original article (Basic research) •     Next Articles

Study on invasiveness of leptospires to endothelial monolayers

DENG Cong1, ZENG Ling-bing2, |ZHANG Yan2, LOU Xiao-li3, HE Ping2, GUO Xiao-kui2, JIANG Xu-cheng1   

  1. 1.Department of Pathology, 2.Department of Microbiology and Parasitology, Basic Medical College, Shanghai Jiaotong University, Shanghai200025, China；3.Central Laboratory, Songjiang District Center Hospital, Shanghai 201600, China
  • Online:2011-05-28 Published:2011-05-27
  • Supported by:

    National High Technology Research and Development Program of China,“863 Program”, 2006AA02Z176；National Natural Science Foundation of China, 30770820；Shanghai Municipal Health Bureau Foundation, 2008045

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Abstract:

Objective To investigate the invasive ability of leptospires with different virulence to endothelial monolayers and the changes in permeability of endothelial monolayers. Methods Intact endothelial monolayer models were constructed with EAhy926 cells and Transwell chamber, and were infected by Leptospira virulent 56606v strains, attenuated 56606a strains, saprophytic Patoc I strains, Salmonella 14028 strains and E.coli DH5α strains, respectively. The numbers of bacteria translocated into the lower Transwell chamber were counted by dark field microscopy after infection for 2 h, 4 h and 8 h, and the permeability of endothelial monolayers to fluorescent particles were detected. 56606v strains and 56606a strains were used to infect EAhy926 cells for 24 h, and apoptosis rates were detected by flow cytometry with Annexin V and PI staining. The morphology of the leptospires penetrating the endothelial monolayers were observed by transmission electron microscopy. Results Two hours after infection, 56606v strains and 14028 strains began to appear in the lower chamber, and 56606a strains and Patoc I strains were not observed until 4 h after infection. The number of strains in the lower chamber increased with time, and the number of 56606v strains in the lower chamber was much larger than those of 56606a strains and Patoc I strains 8 h after infection (P<0.05). Leptospires with different virulence did not cause significant changes in permeability of endothelial monolayers. No apoptosis was detected in endothelial cells infected by 56606v strains or 56606a strains. Transmission electron microscopy revealed that the leptospires mainly penetrated the cytoplasm of endothelial monolayers instead of the intercellular tight junctions. Conclusion The invasive ability of virulent leptospires is much stronger than both attenuated and saprophytic leptospires. There are no changes in permeability and apoptosis of endothelial monolayers infected by leptospires with different virulence.

Key words: leptospira, endothelial monolayer, invasiveness, permeability