Role of Shiga Toxins in Cytotoxicity and Immunomodulatory Effects of Escherichia coli O157:H7 during Host-Bacterial Interactions in vitro

Abstract

Enterohemorrhagic Escherichia coli (EHEC) strains are food-borne pathogens that can cause different clinical conditions. Shiga toxin 2a and/or 2c (Stx2)-producing E. coli O157:H7 is the serotype most frequently associated with severe human disease. In this work we analyzed the hypothesis that host cells participate in Stx2 production, cell damage, and inflammation during EHEC infection. With this aim, macrophage-differentiated THP-1 cells and the intestinal epithelial cell line HCT-8 were incubated with E. coli O157:H7. A time course analysis of cellular and bacterial survival, Stx2 production, stx2 transcription, and cytokine secretion were analyzed in both human cell lines. We demonstrated that macrophages are able to internalize and kill EHEC. Simultaneously, Stx2 produced by internalized bacteria played a major role in macrophage death. In contrast, HCT-8 cells were completely resistant to EHEC infection. Besides, macrophages and HCT-8 infected cells produce IL-1β and IL-8 inflammatory cytokines, respectively. At the same time, bacterial stx2-specific transcripts were detected only in macrophages after EHEC infection. The interplay between bacteria and host cells led to Stx production, triggering of inflammatory response and cell damage, all of which could contribute to a severe outcome after EHEC infections.

Characterization of a Type VI Secretion System vgrG2 Gene in the Pathogenicity of Burkholderia thailandensis BPM

“…The experimental results indicated that the vgrG2 gene may participate in the immune evasion of BPM and play a key role in the evasion of innate immune responses in whole blood. Bacterial adherence to and interaction with RAW264.7 cells are prerequisites for the induction of bacterial infection ( Bruballa et al, 2020 ). We observed the invasion and survival abilities of the BPM, mutant and complemented strains and compared them to the abilities of RAW264.7 cells.…”

The Changes in Bacterial Microbiome Associated with Immune Disorder in Allergic Respiratory Disease

“…Bilophila and Phascolarctobacterium promote pro-inflammatory cytokines associated with innate immune cells while maintaining Th1/Th2 and Treg/Th17 balance to some extent [ 120 , 121 , 122 , 123 , 124 , 125 ]. Other bacteria in this group display a more complex and indeterminate association with inflammation [ 51 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 ]. Escherichia is [ 128 , 129 ] uncertainly associated with IgE production while Prevotella mainly promotes inflammation, but exhibits a negative association with production of IgE [ 131 , 132 ].…”

The changes of microbiota associated with immunological disturbances in allergic respiratory disease

“…[120][121][122][123][124][125] Other bacteria in this group display more complex and uncertain relationships with inflammation. 51,[126][127][128][129][130][131][132][133][134][135][136] Escherichia is uncertainly connected with IgE. 128,129 Prevotella mainly promotes inflammation, but negatively related with IgE.…”