Characterization of Stx2 Tubular Response in a Rat Experimental Model of Hemolytic Uremic Syndrome

Ochoa, Federico; Lago, Néstor; Gerhardt, Elizabeth; Ibarra, Cristina; Zotta, Elsa

doi:10.1159/000319444

Cited by 6 publications

(6 citation statements)

References 49 publications

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“…In this cohort of children with STEC‐HUS we found an acute increase in urinary TGF‐β1 concentrations during the acute phase of the disease. This finding is consistent with studies in a murine model of HUS induced by Shiga toxin, where an increase in renal expression of TGF‐β1 was observed during the first 48 h after injury . Although our data do not provide direct evidence of increased cytokine renal production, it has been shown in different types of glomerulopathies that TGF‐β1 upregulation was followed by an increase in its urinary excretion .…”

Section: Discussionsupporting

confidence: 92%

“…This finding is consistent with studies in a murine model of HUS induced by Shiga toxin, where an increase in renal expression of TGF-b1 was observed during the first 48 h after injury. 20,21 Although our data do not provide direct evidence of increased cytokine renal production, it has been shown in different types of glomerulopathies that TGF-b1 upregulation was followed by an increase in its urinary excretion. 22 Even more important, baseline levels predicted the persistence of renal damage with high accuracy.…”

Section: Discussioncontrasting

confidence: 56%

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Prognostic value of urinary TGF‐β1 in hemolytic uremic syndrome: A pilot study

Balestracci¹,

Roy

Caletti³

2020

Pediatrics International

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Background Transforming growth factor β1 (TGF‐β1) is the main profibrotic cytokine. Its urinary excretion reflects intrarenal production; thus, we conjectured that it is elevated during hemolytic uremic syndrome related to Shiga‐toxin‐producing Escherichia coli (STEC‐HUS). In this pilot study, we explored the ability of baseline TGF‐β1 excretion (exposure variable) to predict renal prognosis at 6 months (outcome variable). In a secondary investigation, we compared changes in cytokine levels during the study period between patients with opposite renal outcomes. Methods Urinary TGF‐β1 concentrations were measured prospectively in 24 children with STEC‐HUS on admission, and at 15, 30, 60, 90, and 180 days. Normal values were obtained from 20 healthy subjects. Results Baseline TGF‐β1 concentrations predicted renal outcomes with an area under the curve of 1 (95%CI 0.85–1; sensitivity 100%, specificity 100%) with the best cutoff level >293.7 pg/mg uCr. All patients with high TGF‐β1 levels developed persistent renal impairment, unlike none with low concentrations (4/4 vs. 20/0 respectively, P = 0.0001). The latter had higher cytokine levels (P < 0.05) at each time point without reaching normal concentrations (<45 pg/mg uCr). Conclusions Baseline urinary TGF‐β1 levels accurately predicted short‐term renal outcomes in STEC‐HUS children, and cytokine excretion during the first 6 months after diagnosis was higher among those with worse evolution. Larger studies are needed to validate these findings.

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Section: Discussionsupporting

confidence: 92%

Section: Discussioncontrasting

confidence: 56%

Prognostic value of urinary TGF‐β1 in hemolytic uremic syndrome: A pilot study

Balestracci¹,

Roy

Caletti³

2020

Pediatrics International

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“…Since Karmali linked sporadic cases of HUS with cytotoxin-producing E. coli isolated from patient feces in a breakthrough discovery in 1983 ( 2 ), numerous in vivo models have been developed to study this syndrome, applying such different animals as non-human primates ( 19 , 20 ), gnotobiotic piglets ( 21 – 25 ), rabbits ( 26 , 27 ), rats ( 28 – 30 ), and mice ( 31 – 34 ). Reportedly, certain aspects of HUS, such as, thrombotic microangiopathy, glomerular damage, and thrombocytopenia, are difficult to reproduce in murine models ( 32 , 33 ).…”

Section: Introductionmentioning

confidence: 99%

Modeling Hemolytic-Uremic Syndrome: In-Depth Characterization of Distinct Murine Models Reflecting Different Features of Human Disease

et al. 2018

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Diarrhea-positive hemolytic-uremic syndrome (HUS) is a renal disorder that results from infections with Shiga-toxin (Stx)-producing Escherichia coli. The aim of this study was to establish well-defined refined murine models of HUS that can serve as preclinical tools to elucidate molecular mechanisms of disease development. C57BL/6J mice were subjected to different doses of Stx2 purified from an E. coli O157:H7 patient isolate. Animals received 300 ng/kg Stx2 and were sacrificed on day 3 to establish an acute model with fast disease progression. Alternatively, mice received 25 ng/kg Stx2 on days 0, 3, and 6, and were sacrificed on day 7 to establish a subacute model with moderate disease progression. Indicated by a rise in hematocrit, we observed dehydration despite volume substitution in both models, which was less pronounced in mice that underwent the 7-day regime. Compared with sham-treated animals, mice subjected to Stx2 developed profound weight loss, kidney dysfunction (elevation of plasma urea, creatinine, and neutrophil gelatinase-associated lipocalin), kidney injury (tubular injury and loss of endothelial cells), thrombotic microangiopathy (arteriolar microthrombi), and hemolysis (elevation of plasma bilirubin, lactate dehydrogenase, and free hemoglobin). The degree of complement activation (C3c deposition), immune cell invasion (macrophages and T lymphocytes), apoptosis, and proliferation were significantly increased in kidneys of mice subjected to the 7-day but not in kidneys of mice subjected to the 3-day regime. However, glomerular and kidney volume remained mainly unchanged, as assessed by 3D analysis of whole mount kidneys using CD31 staining with light sheet fluorescence microscopy. Gene expression analysis of kidneys revealed a total of only 91 overlapping genes altered in both Stx2 models. In conclusion, we have developed two refined mouse models with different disease progression, both leading to hemolysis, thrombotic microangiopathy, and acute kidney dysfunction and damage as key clinical features of human HUS. While intrarenal changes (apoptosis, proliferation, complement deposition, and immune cell invasion) mainly contribute to the pathophysiology of the subacute model, prerenal pathomechanisms (hypovolemia) play a predominant role in the acute model. Both models allow the further study of the pathomechanisms of most aspects of human HUS and the testing of distinct novel treatment strategies.

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“…31 Previously, we reported the immunophenotype changes in tubular cells damaged by Stx2 by TGF-β 1 in rats. 14 We suggest that megalin deficiency is associated with the increased expression of TGF-β 1 that produces the immunophenotype change of tubular cells, and the presence of microalbuminuria at 48 hours post-sStx2 inoculation.…”

Section: A B 400× 400×mentioning

confidence: 81%

Microalbuminuria and early renal response to lethal dose Shiga toxin type 2 in rats

Ochoa

Oltra²,

Gerhardt³

et al. 2012

IJNRD

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In Argentina, hemolytic uremic syndrome (HUS) constitutes the most frequent cause of acute renal failure in children. Approximately 2%–4% of patients die during the acute phase, and one-third of the 96% who survive are at risk of chronic renal sequelae. Little information is available about the direct effect of Shiga toxin type 2 (Stx2) on the onset of proteinuria and the evolution of toxin-mediated glomerular or tubular injury. In this work, rats were injected intraperitoneally with recombinant Escherichia coli culture supernatant containing Stx2 (sStx2; 20 μg/kg body weight) to induce HUS. Functional, immunoblotting, and immunohistochemistry studies were carried out to determine alterations in slit diaphragm proteins and the proximal tubule endocytic system at 48 hours post-inoculation. We detected a significant increase in microalbuminuria, without changes in the proteinuria values compared to the control rats. In immunoperoxidase studies, the renal tubules and glomerular mesangium showed an increased expression of transforming growth factor β1(TGF-β1). The expression of megalin was decreased by immunoperoxidase and the cytoplasm showed a granular pattern of megalin expression by immunofluorescence techniques. Western blot analysis performed in the renal cortex from sStx2-treated and control rats using anti-nephrin and anti-podocalyxin antibodies showed a decreased expression of these proteins. We suggest that the alterations in slit diaphragm proteins and megalin expression could be related to the development of microalbuminuria in response to lethal doses of Stx2.

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Characterization of Stx2 Tubular Response in a Rat Experimental Model of Hemolytic Uremic Syndrome

Cited by 6 publications

References 49 publications

Prognostic value of urinary TGF‐β1 in hemolytic uremic syndrome: A pilot study

Prognostic value of urinary TGF‐β1 in hemolytic uremic syndrome: A pilot study

Modeling Hemolytic-Uremic Syndrome: In-Depth Characterization of Distinct Murine Models Reflecting Different Features of Human Disease

Microalbuminuria and early renal response to lethal dose Shiga toxin type 2 in rats

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