EspF of Enterohemorrhagic Escherichia coli Enhances Apoptosis via Endoplasmic Reticulum Stress in Intestinal Epithelial Cells: An Isobaric Tags for Relative and Absolute Quantitation-Based Comparative Proteomic Analysis.

There have been large foodborne outbreaks related to Enterohemorrhagic Escherichia coli (EHEC) around the world. Among its virulence proteins, the EspF encoded by locus of enterocyte effacement is one of the most known functional effector proteins. In this research, we infected the HT-29 cells with the EHEC wild type strain and EspF-deficient EHEC strain. Via the emerging technique isobaric tags for relative and absolute quantitation (iTRAQ), we explored the pathogenic characteristics of EspF within host cells. Our data showed that the differences regarding cellular responses mainly contained immune regulation, protein synthesis, signal transduction, cellular assembly and organization, endoplasmic reticulum (ER) stress, and apoptosis. Notably, compared with the EspF-deficient strain, the protein processing in the ER and ribosome were upregulated during wild type (WT) infection. Our findings proved that the EspF of Enterohemorrhagic Escherichia coli induced ER stress in intestinal epithelial cells; the ER stress-dependent apoptosis pathway was also activated within the host cells. This study provides insight into the virulence mechanism of protein EspF, which will deepen our general understanding of A/E pathogens and their interaction with host proteins.

Polyphosphate Kinase 1 Is a Pathogenesis Determinant in Enterohemorrhagic Escherichia coli O157:H7.

The ppk1 gene encodes polyphosphate kinase (PPK1), which is the major catalytic enzyme that Escherichia coli utilizes to synthesize inorganic polyphosphate (polyP). The aim of this study was to explore the role of PPK1 in the pathogenesis of Enterohemorrhagic E. coli O157:H7 (EHEC O157:H7). An isogenic in-frame ppk1 deletion mutant (Δppk1) and ppk1 complemented mutant (Cppk1) were constructed and characterized in comparison to wild-type (WT) EHEC O157:H7 strain EDL933w by microscope observation and growth curve analysis. Survival rates under heat stress and acid tolerance, both of which the bacteria would face during pathogenesis, were compared among the three strains. LoVo cells and a murine model of intestinal colitis were used as the in vitro and in vivo models, respectively, to evaluate the effect of PPK1 on adhesion and invasion during the process of pathogenesis. Real-time reverse-transcription PCR of regulatory gene rpoS, adhesion gene eae, and toxin genes stx1 and stx2 was carried out to corroborate the results from the in vitro and in vivo models. The ppk1 deletion mutant exhibited disrupted polyP levels, but not morphology and growth characteristics. The survival rate of the Δppk1 strain under stringent environmental conditions was lower as compared with WT and Cppk1. The in vitro assays showed that deletion of the ppk1 gene reduced the adhesion, formation of attaching and effacing (A/E) lesions, and invasive ability of EHEC O157:H7. Moreover, the virulence of the Δppk1 in BALB/c mice was weaker as compared with the other two strains. Additionally, mRNA expression of rpoS, eae, stx1 and stx2 were consistent with the in vitro and in vivo results. In conclusion: EHEC O157:H7 requires PPK1 for both survival under harsh environmental conditions and virulence in vivo.

Epidemiologic Profile of Overweight and Obesity in Abidjan, Ivory Coast: A Cross-Sectional Study.

Background: In sub-Saharan Africa, the prevalence of overweight and obesity is high, and it is estimated to increase within the next ten years. In Ivory Coast, the rise in and public health consequences of overweight and obese people are evident. Moreover, data concerning this status are scarce, old, local, and describe only a small sample of the population. Objective: This study has been conducted in order to describe the epidemiologic profile of overweight and obese people in Ivory Coast and identify the potential risk factors of obesity. Methods: From January 2014 to July 2017, 2,643 patients aged 17-70 years old from Abidjan of Ivory Coast were recruited. Statistical analysis was carried out using SPSS 20.0. Chi-square test and binary logistic regression analysis were used to identify risk factors for overweight and obesity. Results: Most of our patients were females (86.3%) with an estimated average age of 43.7 ± 12.19 years. Among 2,643 patients recruited in this study, 83.3% were obese and 87.2% were affected by central abdominal obesity. Binary logistic regression analysis identified seven factors significantly associated with overweight and obesity, including females (OR: 2.06; 95% CI [1.58-2.68]), >54 years old of age (OR: 3.71; 95% CI [1.84-7.50]), occupation of salesperson and traders (OR: 2.42; 95% CI [1.78-3.29]), ethnic group of North Mande ethnicity (OR: 1.47; 95% CI [1.07-2.02]), family history of obesity (OR: 1.96; 95% CI [1.46-2.63]), ≥150 minutes of sport practice (OR:0.72; 95% CI [0.55-0.96]), and parous females (OR: 1.63; 95% CI [1.11-2.38]). Conclusions: Overall, gender (female), older age, and occupation were associated with greater risks of overweight and obesity in patients. Ethnic group, pregnancy and family history of obesity posed a lower but significant risk for obesity. More sport practice played a protective role against the acquisition of overweight and obesity.

Clever Cooperation: Interactions Between EspF and Host Proteins.

EspF is a central effector protein of enterohemorrhagic Escherichia coli (EHEC), enteropathogenic E. coli (EPEC), and Citrobacter rodentium (CR) that is secreted through the type III secretion system to host cells. The interaction between EspF and host proteins plays an important role in bacterial pathogenesis. EspF protein binds to host SNX9 and N-WASP proteins to promote the colonization of pathogenic bacteria in intestinal epithelial cells; combines with cytokeratin 18, actin, 14-3-3ζ, Arp2/3, profilin, and ZO-1 proteins to intervene in the redistribution of intermediate filaments, the rearrangement of actin, and the disruption of tight junctions; acts together with Abcf2 to boost host cell intrinsic apoptosis; and collaborates with Anxa6 protein to inhibit phagocytosis. The interaction between EspF and host proteins is key to the pathogenic mechanism of EHEC and EPEC. Here, we review how EspF protein functions through interactions with these 10 host proteins and contributes to the pathogenicity of EHEC/EPEC.