The CXCR4/CXCR7/SDF-1 pathway contributes to the pathogenesis of Shiga toxin–associated hemolytic uremic syndrome in humans and mice
Tania N. Petruzziello-Pellegrini, … , James L. Brunton, Philip A. Marsden
Tania N. Petruzziello-Pellegrini, … , James L. Brunton, Philip A. Marsden
Published January 9, 2012
Citation Information: J Clin Invest. 2012;122(2):759-776. https://doi.org/10.1172/JCI57313.
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Research Article Nephrology

The CXCR4/CXCR7/SDF-1 pathway contributes to the pathogenesis of Shiga toxin–associated hemolytic uremic syndrome in humans and mice

Abstract

Hemolytic uremic syndrome (HUS) is a potentially life-threatening condition. It often occurs after gastrointestinal infection with E. coli O157:H7, which produces Shiga toxins (Stx) that cause hemolytic anemia, thrombocytopenia, and renal injury. Stx-mediated changes in endothelial phenotype have been linked to the pathogenesis of HUS. Here we report our studies investigating Stx-induced changes in gene expression and their contribution to the pathogenesis of HUS. Stx function by inactivating host ribosomes but can also alter gene expression at concentrations that minimally affect global protein synthesis. Gene expression profiling of human microvascular endothelium treated with Stx implicated a role for activation of CXCR4 and CXCR7 by their shared cognate chemokine ligand (stromal cell–derived factor-1 [SDF-1]) in Stx-mediated pathophysiology. The changes in gene expression required a catalytically active Stx A subunit and were mediated by enhanced transcription and mRNA stability. Stx also enhanced the association of CXCR4, CXCR7, and SDF1 mRNAs with ribosomes. In a mouse model of Stx-mediated pathology, we noted changes in plasma and tissue content of CXCR4, CXCR7, and SDF-1 after Stx exposure. Furthermore, inhibition of the CXCR4/SDF-1 interaction decreased endothelial activation and organ injury and improved animal survival. Finally, in children infected with E. coli O157:H7, plasma SDF-1 levels were elevated in individuals who progressed to HUS. Collectively, these data implicate the CXCR4/CXCR7/SDF-1 pathway in Stx-mediated pathogenesis and suggest novel therapeutic strategies for prevention and/or treatment of complications associated with E. coli O157:H7 infection.

Authors

Tania N. Petruzziello-Pellegrini, Darren A. Yuen, Andrea V. Page, Sajedabanu Patel, Anna M. Soltyk, Charles C. Matouk, Dennis K. Wong, Paul J. Turgeon, Jason E. Fish, J.J. David Ho, Brent M. Steer, Vahid Khajoee, Jayesh Tigdi, Warren L. Lee, David G. Motto, Andrew Advani, Richard E. Gilbert, S. Ananth Karumanchi, Lisa A. Robinson, Phillip I. Tarr, W. Conrad Liles, James L. Brunton, Philip A. Marsden

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Figure 3

Stx enhances CXCR4 expression by both transcriptional and posttranscriptional mechanisms.

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Stx enhances CXCR4 expression by both transcriptional and posttranscript...
(A) HMVECs treated with vehicle or 1,000 fM Stx2 for 20 hours were subjected to transcription arrest with 10 μg/ml actinomycin D, and RNA was harvested at various times thereafter. Remaining CXCR4 mRNA was determined using qRT-PCR and normalized to 18S. The mean ± SEM of 3 independent experiments is shown. Half-lives were calculated using exponential regression to be 1.18 ± 0.09 hours in vehicle-treated cells and 19.2 ± 7.8 hours in Stx-treated cells. (B) HMVECs were exposed to 1,000 fM Stx2 for 20 hours, followed by ChIP using anti-RNA polymerase II (Pol II) antibodies. qRT-PCR for CXCR4 was then used to determine the amount of immunoprecipitated DNA (IP DNA). The mean ± SEM of at least 4 independent experiments is shown. (C) HMVECs were maintained under normoxic (21% O2) or hypoxic (<1% O2) conditions for the indicated times. qRT-PCR was used to determine mRNA levels. Data are normalized for 18S levels and are shown relative to normoxic cells. The mean ± SEM of 3 independent experiments is shown. Similar trends were observed whether or not data are normalized to housekeeping genes. (D) Western blot analyses were performed for HIF-1α and HIF-2α in HMVECs treated with 10 fM or 1,000 fM Stx for 6 or 24 hours. Lamin A/C was used as a loading control. Negative control and positive control were normoxic and hypoxic HMVECs. *P < 0.05 vs. vehicle or normoxia.