The oxidative stress induced in vivo by Shiga toxin-2 contributes to the pathogenicity of haemolytic uraemic syndrome

Abstract

SummaryTypical haemolytic uraemic syndrome (HUS) is caused by Shiga toxin (Stx)-producing Escherichia coli infections and is characterized by thrombotic microangiopathy that leads to haemolytic anaemia, thrombocytopenia and acute renal failure. Renal or neurological sequelae are consequences of irreversible tissue damage during the acute phase. Stx toxicity and the acute inflammatory response raised by the host determine the development of HUS. At present there is no specific therapy to control Stx damage. The pathogenic role of reactive oxygen species (ROS) on endothelial injury has been largely documented. In this study, we investigated the in-vivo effects of Stx on the oxidative balance and its contribution to the development of HUS in mice. In addition, we analysed the effect of anti-oxidant agents as therapeutic tools to counteract Stx toxicity. We demonstrated that Stx induced an oxidative imbalance, evidenced by renal glutathione depletion and increased lipid membrane peroxidation. The increased ROS production by neutrophils may be one of the major sources of oxidative stress during Stx intoxication. All these parameters were ameliorated by anti-oxidants reducing platelet activation, renal damage and increasing survival. To conclude, Stx generates a pro-oxidative state that contributes to kidney failure, and exogenous antioxidants could be beneficial to counteract this pathogenic pathway.

Retinoid Levels Influence Enterohemorrhagic Escherichia coli Infection and Shiga Toxin 2 Susceptibility in Mice

“…PMNs were isolated from a pool of heparinized blood obtained from two mice. The cells were harvested by Ficoll-Hypaque separation, followed by dextran sedimentation, as described by Gomez et al (16).…”

“…A high peripheral blood PMN count at presentation is the poor-prognosis factor most consistently reported, and the degree of renal impairment has been correlated with the level of activation of circulating PMNs (15). Recently, it has been demonstrated that Stx2 induces an oxidative imbalance in vivo, and ROS production by neutrophils may be one of the major sources of oxidative stress during Stx intoxication (16), contributing to the amplification of microvascular injury in the kidneys (17).…”

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

“…Stx2 intoxication induced a marked prothrombotic status and simultaneously a pro-oxidative imbalance demonstrated in both, experimental mouse models [31], and most important in HUS-patients [36,37]. Considering that NAC is a well-known anti-oxidant and glutathione precursor [38], we decided to evaluate if it was able to inhibit Stx2-mediated effects on HGEC cultures.…”

“…Furthermore, it is capable to induce oxidative stress and reactive oxidative species (ROS) generation in various cellular types such as endothelial cells [18], platelets [29], and neutrophils [30]. The involvement of the oxidative stress in tissue damage and renal failure processes during Stx-intoxication has also been subject of investigation; oxidative stress is generated by Stx systemically and locally in the kidney and has been shown to enhance platelet activation [31]. Thus, oxidative stress and platelet-derived sCD40L could stimulate each other.…”

HUS and the case for complement

“…Upon internalization, Stx triggers proinflammatory signals, 55 promotes chemokine release, upregulates leukocyte adhesion molecules and TF, suppresses endothelial TF pathway inhibitor and thrombomodulin, induces platelet-neutrophil interactions, 41 promotes release of TFbearing microparticles, 63 and induces neutrophil production of reactive oxygen species. 64 Stx also interferes with ULVWF cleavage by ADAMTS13 65 and FH, 66 enhancing platelet adhesion/aggregation. Overall, Stx uses multiple means to promote thrombosis, not all of which are sensitive to anticomplement interventions.…”