Action of Shiga Toxin Type-2 and Subtilase Cytotoxin on Human Microvascular Endothelial Cells

Amaral, María Marta; Sacerdoti, Flavia; Jancic, Carolina; Repetto, Horacio A.; Paton, Adrienne W.; Paton, James C.; Ibarra, Cristina

doi:10.1371/journal.pone.0070431

Cited by 47 publications

(69 citation statements)

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“…This strain was isolated from a case of HUS in the south of Australia. The subtilase cytotoxin was shown to cause HUS-like symptoms in mice and apoptosis in human epithelial cells (7)(8)(9). Subtilase cytotoxin genes were detected in a variety of LEE-negative STEC strains of human, ovine, and game origin (10)(11)(12)(13)(14).…”

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confidence: 99%

Cytotoxic and Apoptotic Effects of Recombinant Subtilase Cytotoxin Variants of Shiga Toxin-Producing Escherichia coli

et al. 2015

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In this study, the cytotoxicity of the recently described subtilase variant SubAB 2-2 of Shiga toxin-producing Escherichia coli was determined and compared to the plasmid-encoded SubAB 1 and the chromosome-encoded SubAB 2-1 variant. The genes for the respective enzymatic active (A) subunits and binding (B) subunits of the subtilase toxins were amplified and cloned. The recombinant toxin subunits were expressed and purified. Shiga toxin-producing Escherichia coli (STEC) strains are zoonotic bacterial pathogens causing a variety of symptoms in humans, ranging from relatively mild forms, such as diarrhea, to hemorrhagic colitis and the life-threatening hemolytic-uremic syndrome (HUS) (1). Besides Shiga toxin, the best-characterized pathogenicity factor for the development of serious diseases is the locus of enterocyte effacement (LEE), encoding a type III secretion system and associated effector proteins (2, 3). Other pathogenicity factors can be involved in the development of human disease (4, 5). An example is the subtilase cytotoxin (SubAB), which is located on a 163-kb plasmid of STEC E. coli O113:H21 strain 98NK2 (6). This strain was isolated from a case of HUS in the south of Australia. The subtilase cytotoxin was shown to cause HUS-like symptoms in mice and apoptosis in human epithelial cells (7-9). Subtilase cytotoxin genes were detected in a variety of LEE-negative STEC strains of human, ovine, and game origin (10-14). Furthermore, strains from human origin were shown to cause symptoms in humans ranging from watery diarrhea to fully developed HUS (15, 16).The SubAB toxin is a typical AB 5 toxin, composed of an enzymatically active A subunit (SubA) and a B pentamer (SubB), which mediates the uptake of the toxin into target cells by binding to a specific surface sialic acid, namely, N-glycolylneuraminic acid (Neu5Gc) (17). Neu5Gc is present in most mammals but is not synthesized by human cells due to a 92-bp deletion in the cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) gene (18). However, it was shown that human cells are able to incorporate Neu5Gc from external sources (19). Inside the eukaryotic cell, the enzymatic active A subunit acts as a subtilisinlike serine protease. SubA cleaves the cellular endoplasmic reticulum chaperone GRP78/BiP at an L-L motif on position 416 between the N-terminal ATPase domain and the C-terminal protein binding domain (20). This highly specific protease activity is unique within AB 5 toxins and leads to the accumulation of unfolded proteins in the endoplasmic reticulum. This accumulation induces the unfolded protein response (UPR), which in the end results in the death of the affected cell (21). Yahiro and coworkers demonstrated that binding of SubAB to one of four different cell surface receptors, namely, NG2, hepatocyte growth factor receptor (Met), L1 cell adhesion molecule (CAM), and ß1 integrin (ITG), induces signals which also result in apoptosis of HeLa cells without internalization of SubAB (22). However, the underlying mechanism is not completely u...

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Cytotoxic and Apoptotic Effects of Recombinant Subtilase Cytotoxin Variants of Shiga Toxin-Producing Escherichia coli

et al. 2015

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“…The Ethics Committee of the University of Buenos Aires approved the use of human renal tissues for research purposes. The method used for HGEC isolation was previously described [57].…”

Section: Hgec Culturesmentioning

confidence: 99%

“…HGEC were seeded in glass coverslips and after treatments cells were fixed for 2 h at room temperature with alcohol 96º, stained with (H&E) hematoxylin-eosin and observed by light microscopy as previously described [57,58].…”

Section: Hematoxylin-eosin (Hande) Stainingmentioning

confidence: 99%

Soluble CD40 Iigand and Oxidative Response Are Reciprocally Stimulated during Shiga Toxin-Associated Hemolytic Uremic Syndrome

Recalde¹,

Álvarez²,

Alberto³

et al. 2017

Preprint

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Shiga toxin (Stx) produced by Escherichia coli is the main pathogenic factor of diarrhea-associated hemolytic uremic syndrome (HUS), which is characterized by obstruction of renal microvasculature by platelet-fibrin thrombi. It is well known that the oxidative imbalance generated by Stx induces platelet activation, contributing to thrombus formation. Moreover, activated platelets release soluble CD40 ligand (sCD40L) which in turn contributes to oxidative imbalance, triggering the release of reactive oxidative species (ROS) on various cellular types. The aim of this work was to determine if the interaction between the oxidative response and platelet-derived sCD40L participates in the pathogenic mechanism during HUS. Activated human glomerular endothelial cells (HGEC) by Stx2 induced platelets to adhere to them.Although platelet adhesion did not contribute to endothelial damage, high levels of sCD40L were released to the medium. The release of sCD40L by activated platelets was inhibited by antioxidant treatment.Furthermore, we found increased levels of sCD40L in plasma from HUS patients, which were also able to trigger the respiratory burst in monocytes, in a sCD40L-dependent manner. Thus, we concluded that platelet-derived sCD40L and the oxidative response are reciprocally stimulated during Stx2-associated HUS.This process may contribute to the evolution of glomerular occlusion and the microangiopathic lesions.

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“…21 The main reason why gastrointestinal infection particularly affects kidneys is thought to be the tissue tropism of Shiga-toxin on the basis of the strong expression of Gb3 on the glomerular endothelium. 22 …”

Section: Introductionmentioning

confidence: 99%

HUS and atypical HUS

Jokiranta

2017

Blood

239

260

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Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy characterized by intravascular hemolysis, thrombocytopenia, and acute kidney failure. HUS is usually categorized as typical, caused by Shiga toxin–producing Escherichia coli (STEC) infection, as atypical HUS (aHUS), usually caused by uncontrolled complement activation, or as secondary HUS with a coexisting disease. In recent years, a general understanding of the pathogenetic mechanisms driving HUS has increased. Typical HUS (ie, STEC-HUS) follows a gastrointestinal infection with STEC, whereas aHUS is associated primarily with mutations or autoantibodies leading to dysregulated complement activation. Among the 30% to 50% of patients with HUS who have no detectable complement defect, some have either impaired diacylglycerol kinase ε (DGKε) activity, cobalamin C deficiency, or plasminogen deficiency. Some have secondary HUS with a coexisting disease or trigger such as autoimmunity, transplantation, cancer, infection, certain cytotoxic drugs, or pregnancy. The common pathogenetic features in STEC-HUS, aHUS, and secondary HUS are simultaneous damage to endothelial cells, intravascular hemolysis, and activation of platelets leading to a procoagulative state, formation of microthrombi, and tissue damage. In this review, the differences and similarities in the pathogenesis of STEC-HUS, aHUS, and secondary HUS are discussed. Common for the pathogenesis seems to be the vicious cycle of complement activation, endothelial cell damage, platelet activation, and thrombosis. This process can be stopped by therapeutic complement inhibition in most patients with aHUS, but usually not those with a DGKε mutation, and some patients with STEC-HUS or secondary HUS. Therefore, understanding the pathogenesis of the different forms of HUS may prove helpful in clinical practice.

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Action of Shiga Toxin Type-2 and Subtilase Cytotoxin on Human Microvascular Endothelial Cells

Cited by 47 publications

References 50 publications

Cytotoxic and Apoptotic Effects of Recombinant Subtilase Cytotoxin Variants of Shiga Toxin-Producing Escherichia coli

Cytotoxic and Apoptotic Effects of Recombinant Subtilase Cytotoxin Variants of Shiga Toxin-Producing Escherichia coli

Soluble CD40 Iigand and Oxidative Response Are Reciprocally Stimulated during Shiga Toxin-Associated Hemolytic Uremic Syndrome

HUS and atypical HUS

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