Leptospira interrogans causes quantitative and morphological disturbances in adherens junctions and other biological groups of proteins in human endothelial cells

Abstract

Pathogenic Leptospira transmits from animals to humans, causing the zoonotic life-threatening infection called leptospirosis. This infection is reported worldwide with higher risk in tropical regions. Symptoms of leptospirosis range from mild illness to severe illness such as liver damage, kidney failure, respiratory distress, meningitis, and fatal hemorrhagic disease. Invasive species of Leptospira rapidly disseminate to multiple tissues where this bacterium damages host endothelial cells, increasing vascular permeability. Despite the burden in humans and animals, the pathogenic mechanisms of Leptospira infection remain to be elucidated. The pathogenic leptospires adhere to endothelial cells and permeabilize endothelial barriers in vivo and in vitro. In this study, human endothelial cells were infected with the pathogenic L. interrogans serovar Copenhageni or the saprophyte L. biflexa serovar Patoc to investigate morphological changes and other distinctive phenotypes of host cell proteins by fluorescence microscopy. Among those analyzed, 17 proteins from five biological classes demonstrated distinctive phenotypes in morphology and/or signal intensity upon infection with Leptospira. The affected biological groups include: 1) extracellular matrix, 2) intercellular adhesion molecules and cell surface receptors, 3) intracellular proteins, 4) cell-cell junction proteins, and 5) a cytoskeletal protein. Infection with the pathogenic strain most profoundly disturbed the biological structures of adherens junctions (VE-cadherin and catenins) and actin filaments. Our data illuminate morphological disruptions and reduced signals of cell-cell junction proteins and filamentous actin in L. interrogans-infected endothelial cells. In addition, Leptospira infection, regardless of pathogenic status, influenced other host proteins belonging to multiple biological classes. Our data suggest that this zoonotic agent may damage endothelial cells via multiple cascades or pathways including endothelial barrier damage and inflammation, potentially leading to vascular hyperpermeability and severe illness in vivo. This work provides new insights into the pathophysiological mechanisms of Leptospira infection.

Pathology and pathogenesis of human leptospirosis: a commented review

“…A recent study by Sato and Coburn 33 showed that the most important finding seen in L. interrogans was the disruption of adherens junctions due to protein alterations. VE-cadherins, p120 catenin, alpha and beta catenins are specifically involved in the process.…”

An extracellular Leptospira interrogans leucine‐rich repeat protein binds human E‐ and VE‐cadherins

“…The dermal human microvascular endothelial cell line (HMEC‐1) was acquired and grown as described previously (Sato & Coburn, ). To use HMEC‐1 for protein binding tests, cells were seeded at 4.8 × 10 5 per well on sterile coverslips placed in wells of 12‐well plates for 2‐day growth.…”

“…Indeed, antibodies against VE-Cadherin have been known to induce vascular permeability in mice, potentially to the point of haemorrhage (Corada et al, 1999), a phenomenon also observed during leptospirosis (Plank & Dean, 2000). Furthermore, pathogenic, but not saprophytic, Leptospira have been shown to interrupt cell-to-cell junctions in vitro (Sato & Coburn, 2017). Enhanced vascular permeability facilitated by LIC10831 may allow the bacterium to escape host blood vessels to take up residence in preferred host tissues (Barnett et al, 1999;Ozuru et al, 2017).…”

“…The dermal human microvascular endothelial cell line (HMEC-1) was acquired and grown as described previously (Sato & Coburn, 2017).…”

Un nouveau regard sur la leptospirose humaine

“…Un défaut de reconnaissance du lipopolysaccharide des spirochètes par les défenses innées de l'organisme, et en particulier par le Toll Like Receptor 4 (TLR4) chez l'humain serait impliqué dans la réponse insuffisante de l'hôte (Werts et al 2001). Les leptospires ont un tropisme particulier pour le foie, les reins, l'endothélium vasculaire et les poumons (Sato & Coburn, 2017). L'infection induit alors une réponse inflammatoire particulièrement forte avec libération de grande quantité de cytokines pro-inflammatoires et une forte élévation de la protéine C réactive (CRP).…”