Abstract
Shiga toxin-producing Escherichia coli (STEC) O113:H21 strains are associated with human diarrhea and some strains may cause hemolytic–uremic syndrome (HUS). In Brazil, these strains are commonly found in cattle but, so far, were not isolated from HUS patients. Here, a system biology approach was used to investigate the differential transcriptomic and phenotypic responses of enterocyte-like Caco-2 cells to two STEC O113:H21 strains with similar virulence factor profiles (i.e., expressing stx2, ehxA, epeA, espA, iha, saa, sab, and subA): EH41 (Caco-2/EH41), isolated from a HUS patient in Australia, and Ec472/01 (Caco-2/Ec472), isolated from bovine feces in Brazil, during a 3 h period of bacteria–enterocyte interaction. Gene co-expression network analysis for Caco-2/EH41 revealed a quite abrupt pattern of topological variation along 3 h of enterocyte–bacteria interaction when compared with networks obtained for Caco-2/Ec472. Transcriptional module characterization revealed that EH41 induces inflammatory and apoptotic responses in Caco-2 cells just after the first hour of enterocyte–bacteria interaction, whereas the response to Ec472/01 is associated with cytoskeleton organization at the first hour, followed by the expression of immune response modulators. Scanning electron microscopy showed more intense microvilli destruction in Caco-2 cells exposed to EH41 when compared to those exposed to Ec472/01. Altogether, these results show that EH41 expresses virulence genes, inducing a distinctive host cell response, and is likely associated with severe pathogenicity.
Highlights
Hemolytic-uremic syndrome (HUS) is a thrombotic microangiopathy clinically defined by thrombocytopenia, non-immune hemolytic anemia, and renal failure
KEGG pathway-based enrichment analysis for these three differentially expressed (DE) gene sets showed that in the Caco-2/EH41 group, a total of 317 DE genes are over-represented in pathways related to inflammation, phagocytosis, and adaptive immune response, while only 164 DE genes appear in these pathways in the Caco-2/Ec472 group
We employed dynamic gene co-expression network (GCN) analysis in order to investigate the differential response of Caco-2 cells to two Shiga toxin-producing Escherichia coli (STEC) strains, one patient-isolated and associated with HUS (EH41) and the other (Ec472/01) isolated from cattle feces in Brazil
Summary
Hemolytic-uremic syndrome (HUS) is a thrombotic microangiopathy clinically defined by thrombocytopenia, non-immune hemolytic anemia, and renal failure. The pathogenesis of STEC in intestinal illness usually entails bacterial attachment to the intestinal epithelial cells and microvillus destruction and translocation of Stx [2,3,4,5]. There are, LEE-negative STEC strains, such as O113:H21, that do not produce intimin but can cause HUS [2,3,4,5]. This serotype harbors several virulence genes, such as sab, subAB, ehxA, and possibly other yet unknown virulence factors, but it is not clear how all these genes/factors act together with Stx in promoting pathogenesis [6,7]
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