Responses of Human Endothelial Cells to Pathogenic and Non-Pathogenic Leptospira Species

Denise G. Martinez-Lopez,Mark Fahey,Jenifer Coburn,Albert I. Ko

doi:10.1371/journal.pntd.0000918

Denise G. Martinez-Lopez, Mark Fahey + Show 2 more

Open Access

https://doi.org/10.1371/journal.pntd.0000918

Copy DOI

Abstract

Leptospirosis is a widespread zoonotic infection that primarily affects residents of tropical regions, but causes infections in animals and humans in temperate regions as well. The agents of leptospirosis comprise several members of the genus Leptospira, which also includes non-pathogenic, saprophytic species. Leptospirosis can vary in severity from a mild, non-specific illness to severe disease that includes multi-organ failure and widespread endothelial damage and hemorrhage. To begin to investigate how pathogenic leptospires affect endothelial cells, we compared the responses of two endothelial cell lines to infection by pathogenic versus non-pathogenic leptospires. Microarray analyses suggested that pathogenic L. interrogans and non-pathogenic L. biflexa triggered changes in expression of genes whose products are involved in cellular architecture and interactions with the matrix, but that the changes were in opposite directions, with infection by L. biflexa primarily predicted to increase or maintain cell layer integrity, while L. interrogans lead primarily to changes predicted to disrupt cell layer integrity. Neither bacterial strain caused necrosis or apoptosis of the cells even after prolonged incubation. The pathogenic L. interrogans, however, did result in significant disruption of endothelial cell layers as assessed by microscopy and the ability of the bacteria to cross the cell layers. This disruption of endothelial layer integrity was abrogated by addition of the endothelial protective drug lisinopril at physiologically relevant concentrations. These results suggest that, through adhesion of L. interrogans to endothelial cells, the bacteria may disrupt endothelial barrier function, promoting dissemination of the bacteria and contributing to severe disease manifestations. In addition, supplementing antibiotic therapy with lisinopril or derivatives with endothelial protective activities may decrease the severity of leptospirosis.

Highlights

Leptospirosis is a geographically widespread zoonosis that has emerged as a significant public health problem in urban slums, in the tropics
Our analyses suggested that pathogenic L. interrogans and non-pathogenic L. biflexa caused changes in expression of genes whose products are involved in cellular architecture and interactions with the matrix, but that the changes were in opposite directions, with infection by L. biflexa primarily maintaining cell layer integrity, while L. interrogans disrupted cell layers
L. interrogans caused significant disruption of endothelial cell layers, but this damage could be abrogated by the endothelial protective drug lisinopril

Summary

Introduction

Leptospirosis is a geographically widespread zoonosis that has emerged as a significant public health problem in urban slums, in the tropics. The infection is caused by species of spirochetes belonging to the genus Leptospira. There are more than 200 serovars of Leptospira distributed among both pathogenic and non-pathogenic species [1]. The pathogenicity of different strains can vary considerably depending on the host species and age, and on the infecting serovar [2]. The spirochete’s mode of entry is through mucous membranes and cuts or abrasions on the skin [1]. The organisms travel through the bloodstream to multiple sites, and may cause liver and kidney damage, meningitis, and a variety of other inflammatory conditions. If the host survives the acute infection, leptospires can persist in the proximal renal tubules for weeks to months, protected from antibodies and causing little to no inflammation. The bacteria are shed in the urine, and animal urine contamination of water is the primary source of human exposure

Methods

Results

Conclusion