title: Differential effects of Escherichia coli subtilase cytotoxin and Shiga toxin 2 on chemokine and proinflammatory cytokine expression in human macrophage, colonic epithelial, and brain microvascular endothelial cell lines.
abstract: Subtilase cytotoxin (SubAB) is the prototype of a recently emerged family of AB5 cytotoxins produced by Shiga-toxigenic Escherichia coli (STEC). Its mechanism of action involves highly specific A-subunit-mediated proteolytic cleavage of the essential endoplasmic reticulum (ER) chaperone BiP. Our previous in vivo studies showed that intraperitoneal injection of purified SubAB causes a major redistribution of leukocytes and elevated leukocyte apoptosis in mice, as well as profound splenic atrophy. In the current study, we investigated selected chemokine and proinflammatory cytokine responses to treatment with SubAB, a nontoxic derivative (SubAA272B), or Shiga toxin 2 (Stx2) in human macrophage (U937), brain microvascular endothelial (HBMEC), and colonic epithelial (HCT-8) cell lines, at the levels of secreted protein, cell-associated protein, and gene expression. Stx2 treatment upregulated expression of chemokines and cytokines at both the protein and mRNA levels. In contrast, SubAB induced significant decreases in secreted interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) in all three tested cell lines and a significant decrease in secreted IL-6 in HBMECs. The downregulation of secreted chemokines or cytokines was not observed in SubAA272B-treated cells, indicating a requirement for BiP cleavage. The downregulation of secreted chemokines and cytokines by SubAB was not reflected at the mRNA and cell-associated protein levels, suggesting a SubAB-induced export defect.
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia.
authors.forename: Trisha J
authors.initials: TJ
authors.lastname: Rogers
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia.
authors.forename: James C
authors.initials: JC
authors.lastname: Paton
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia adrienne.paton@adelaide.edu.au.
authors.forename: Adrienne W
authors.initials: AW
authors.lastname: Paton
mesh_terms: D001921:Brain / Q000276:immunology* / Q000382:microbiology; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000235:genetics / Q000276:immunology; D018932:Chemokine CCL2 / Q000235:genetics / Q000276:immunology; D003106:Colon / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D042783:Endothelial Cells / Q000276:immunology* / Q000382:microbiology; D004730:Endothelium, Vascular / Q000276:immunology / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D016209:Interleukin-8 / Q000235:genetics / Q000276:immunology; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology; D000071701:Regulatory Factor X Transcription Factors; D022641:Shiga Toxin 2 / Q000235:genetics / Q000276:immunology*; D013381:Subtilisins / Q000235:genetics / Q000276:immunology*; D051742:Transcription Factor CHOP / Q000235:genetics / Q000276:immunology; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology; D014158:Transcription, Genetic / Q000235:genetics / Q000276:immunology; D020298:U937 Cells; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; C497249:DDIT3 protein, human; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D016209:Interleukin-8; D000071701:Regulatory Factor X Transcription Factors; D022641:Shiga Toxin 2; D014157:Transcription Factors; D051742:Transcription Factor CHOP; D013381:Subtilisins; C527234:subtilase cytotoxin, E coli