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 February 1, 2012
Citation Information: J Clin Invest. 2012;122(2):759-776. doi:10.1172/JCI57313.
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Categories: 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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Stx have potent effects on endothelial cell metabolism and phenotype. HM...

Figure 1

Stx have potent effects on endothelial cell metabolism and phenotype.

HMVECs or HUVECs were treated with vehicle (Veh) or the indicated concentrations of (A) Stx2, (B) Stx1 B subunit alone (B) (1,000 fM), or holotoxin with a double mutation in the A subunit (A mut) (1,000 fM) for 24 hours. One hour before harvest, 1 μCi [3H]leucine was added to assess de novo protein synthesis. Radioactivity incorporated into TCA-precipitable material was quantitated, and data were normalized to vehicle-treated cells. The mean ± SEM of 14 experiments (HMVECs with Stx2), 5 experiments (HUVECs), or 3 experiments (mutants), triplicate determinations, is shown. (C) HMVECs (n = 6 replicates) were treated with Stx2 (10 fM, 24 hours) or vehicle and subjected to Affymetrix GeneChip gene expression profiling. By combining probe sets identified as differentially expressed by all preprocessing algorithms and removing redundant probe sets, i.e., probe sets mapping to the same gene, it was determined that 86.2% of differentially expressed genes (318 out of 369 unique genes) were upregulated by treatment with Stx. (D) The top 30 differentially expressed probe sets (based on magnitude of differential expression) were summarized in a heat map with hierarchical clustering. Processed signal intensities (computed using the mmgMOS preprocessing algorithm) are depicted on a log2 scale, with rows representing differentially expressed probe sets and columns representing Stx- or vehicle-treated samples. Note that several probe sets correspond to the same genes.