The infection of microvascular endothelial cells with ExoU-producing Pseudomonas aeruginosa triggers the release of von Willebrand factor and platelet adhesion

Freitas, Carla; Assis, Monique Ribeiro de; Saliba, Alessandra Mattos; Morandi, Verônica; Figueiredo, Camila C.; Pereira, Mirian Cláudia de Souza; Plotkowski, Maria-Cristina

doi:10.1590/s0074-02762012000600004

Cited by 7 publications

(7 citation statements)

References 35 publications

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“…The importance of ExoU in disrupting host responses directed by lung endothelial cells is an emerging field of interest [32,[36][37][38][39][40]. Our previous work has shown that P. aeruginosa infection of PMVECs induces activation of caspase-1-dependent inflammation [44,45].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, ExoU disrupts inflammatory signaling and is cytotoxic to epithelial and immune cells [12,23,[31][32][33][34][35]. While the effects of ExoU on lung epithelial and immune cells are well studied, a role for ExoU in disrupting lung endothelial cell function has only recently emerged [32,[36][37][38][39][40]. Lung endothelial cells are a barrier to proteinaceous fluid flux into tissue and airspaces, and in addition, play an important role in regulating inflammation.…”

Section: Introductionmentioning

confidence: 99%

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ExoU Induces Lung Endothelial Cell Damage and Activates Pro-Inflammatory Caspase-1 during Pseudomonas aeruginosa Infection

Hardy

Tuckey

Renema

et al. 2022

Toxins

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The Gram-negative, opportunistic pathogen Pseudomonas aeruginosa utilizes a type III secretion system to inject exoenzyme effectors into a target host cell. Of the four best-studied exoenzymes, ExoU causes rapid cell damage and death. ExoU is a phospholipase A2 (PLA2) that hydrolyses host cell membranes, and P. aeruginosa strains expressing ExoU are associated with poor outcomes in critically ill patients with pneumonia. While the effects of ExoU on lung epithelial and immune cells are well studied, a role for ExoU in disrupting lung endothelial cell function has only recently emerged. Lung endothelial cells maintain a barrier to fluid and protein flux into tissue and airspaces and regulate inflammation. Herein, we describe a pulmonary microvascular endothelial cell (PMVEC) culture infection model to examine the effects of ExoU. Using characterized P. aeruginosa strains and primary clinical isolates, we show that strains expressing ExoU disrupt PMVEC barrier function by causing substantial PMVEC damage and lysis, in a PLA2-dependent manner. In addition, we show that strains expressing ExoU activate the pro-inflammatory caspase-1, in a PLA2-dependent manner. Considering the important roles for mitochondria and oxidative stress in regulating inflammatory responses, we next examined the effects of ExoU on reactive oxygen species production. Infection of PMVECs with P. aeruginosa strains expressing ExoU triggered a robust oxidative stress compared to strains expressing other exoenzyme effectors. We also provide evidence that, intriguingly, ExoU PLA2 activity was detectable in mitochondria and mitochondria-associated membrane fractions isolated from P. aeruginosa-infected PMVECs. Interestingly, ExoU-mediated activation of caspase-1 was partially inhibited by reactive oxygen species scavengers. Together, these data suggest ExoU exerts pleiotropic effects on PMVEC function during P. aeruginosa infection that may inhibit endothelial barrier and inflammatory functions.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

ExoU Induces Lung Endothelial Cell Damage and Activates Pro-Inflammatory Caspase-1 during Pseudomonas aeruginosa Infection

Hardy

Tuckey

Renema

et al. 2022

Toxins

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“…On the other hand, because cultured endothelial cells are not exposed to fluid shear, uncleaved ultra-large vWF is likely to remain anchored to cell membranes (Freitas et al 2012). Such anchorage would explain the increased expression of surface-associated vWF, as detected by immunofluorescence microscopy.…”

Section: Discussionmentioning

confidence: 99%

“…vWF is present in two different forms: (1) small vWF dimers which are secreted into the plasma, and (2) granular vWF multimers which are stored cell-bound in Weibel-Palade bodies for rapid mobilization in response to cell stress condition (Wagner & Bonfanti 1991). An increased plasma concentration of vWF has been detected in individuals with bacterial infection and has been suggested to be a marker of endothelium activation (Freitas et al 2012). In addition, vWF levels were also found to be significantly higher in patients who did not survive the (Durand et al 1993).…”

Section: Introductionmentioning

confidence: 99%

Streptococcus pneumoniae Infection Increases Expression of von Willebrand Factor (vWF) in a Mouse Brain Endothelium Model

Rahman¹

2018

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Faktor von Willebrand (vWF) adalah glikoprotein multimerik besar yang dikeluarkan secara normal oleh sel-sel endotelial otak dan ianya wujud sebagai protein beredar di dalam darah tetapi struktur asal dan matang vWF tidak terbahagi. Jangkitan pneumokokus boleh menyebabkan pembelahan protein, sehingga membentuk beberapa multimer dengan saiz yang berbeza. Kajian ini telah menguji hipotesis adakah jangkamasa jangkitan Streptococcus pneumoniae boleh menentukan pembentukan saiz vWF. Sel-sel endotelial otak tikus (bEnd.3) telah dijangkiti pada waktu tertentu dengan Streptococcus pneumoniae (serotype 19F). Mikroskopi immunofluoresensi telah dilakukan dan dianalisa dengan sewajarnya. Sel-sel juga diekstrak dan kandungan protein telah dipisahkan ke dalam saiz yang berbeza dengan menggunakan Western blot. Ekspresi vWF kemudian dianalisa dan dibandingkan antara sampel dan antara jangkamasa jangkitan tertentu. Pengeluaran vWF adalah didapati meningkat semasa jangkitan. Walaupun pelbagai perkara tidak spesifik boleh menyebabkan pembahagian vWF, kajian ini menunjukkan bahawa bentuk pembahagian vWF adalah berkemungkinan bergantung pada jangkamasa jangkitan bakteria ini.

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“…The T3SS can secrete exoenzymes S, T, U and Y. ExoU directly lyses ECs through its phospholipase activity, and this is partly achieved through the induction of oxidative stress [11,12]. ExoU can also induce a pro-thrombotic state, by causing ECs to release von Willebrand Factor (vWF) and vWF-expressing microparticles, resulting in increased platelet adhesion and disrupting vascular flow [13]. …”

Section: Toxins That Disrupt Endothelial Barrier Function Directlymentioning

confidence: 99%

Bacteria and endothelial cells: a toxic relationship

Lubkin

Torres

2017

Current Opinion in Microbiology

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Pathogenic bacteria use the bloodstream as a highway for getting around the body, and thus have to find ways to enter and exit through the endothelium. Many bacteria approach this problem by producing toxins that can breach the endothelial barrier through diverse creative mechanisms, including directly killing endothelial cells (ECs), weakening the cytoskeleton within ECs, and breaking the junctions between ECs. Toxins can also modulate the immune response by influencing endothelial biology, and can modulate endothelial function by influencing the response of leukocytes. Understanding these interactions, in both the in vitro and in vivo contexts, is of critical importance for designing new therapies for sepsis and other severe bacterial diseases.

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The infection of microvascular endothelial cells with ExoU-producing Pseudomonas aeruginosa triggers the release of von Willebrand factor and platelet adhesion

Cited by 7 publications

References 35 publications

ExoU Induces Lung Endothelial Cell Damage and Activates Pro-Inflammatory Caspase-1 during Pseudomonas aeruginosa Infection

ExoU Induces Lung Endothelial Cell Damage and Activates Pro-Inflammatory Caspase-1 during Pseudomonas aeruginosa Infection

Streptococcus pneumoniae Infection Increases Expression of von Willebrand Factor (vWF) in a Mouse Brain Endothelium Model

Bacteria and endothelial cells: a toxic relationship

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