Enteroaggregative Escherichia coli induced activation of epidermal growth factor receptor contributes to IL-8 secretion by cultured human intestinal epithelial cells

Structural basis of aggregative adherence fimbriae II interactions with sialic acid, mucin, and human intestinal cells

Enteroaggregative Escherichia coli (EAEC) is a common cause of diarrhea worldwide and is associated with growth faltering in developing countries. EAEC are defined by a characteristic adherence pattern mediated by the aggregative adherence fimbriae (AAFs). Despite the critical role of AAF in the definition of the EAEC pathotype, it is not known what host molecules mediate adherence and EAEC pathogenesis during infection of the human gastrointestinal tract. Multiple receptor candidates have been proposed based on in vitro experimentation. We propose that AAFs interact with multiple receptors during colonization of the human gastrointestinal mucosa, and we hypothesize that structural features of the AafA protein (the major subunit of AAF variant II produced by EAEC strain 042) promote these diverse interactions. In this study, we utilize a panel of AafA variants encoding single amino acid substitutions to understand the role of individual residues in biofilm formation as well as adherence to mucin, fibronectin, and human intestinal cells. We identify both charged and uncharged residues that participate in these interactions, and these residues cluster in two regions of the protein that may define a binding pocket at the junction of polymerized subunits. Although both bovine submaxillary mucin and human fibronectin are sialylated molecules, adherence to mucin is diminished by the removal of sialic acid residues while adherence to fibronectin is not, suggesting that the mechanisms of adherence to these molecules are distinct. Overall, our data provide insight into the structural features that determine AAF/II binding to mucin, sialic acid, and human intestinal cells.

Berberine: Potential preventive and therapeutic strategies for human colorectal cancer

Colorectal cancer (CRC) is a common digestive tract tumor, with incidences continuing to rise. Although modern medicine has extended the survival time of CRC patients, its adverse effects and the financial burden cannot be ignored. CRC is a multi-step process and can be caused by the disturbance of gut microbiome and chronic inflammation's stimulation. Additionally, the presence of precancerous lesions is also a risk factor for CRC. Consequently, scientists are increasingly interested in identifying multi-target, safe, and economical herbal medicine and natural products. This paper summarizes berberine's (BBR) regulatory mechanisms in the occurrence and development of CRC. The findings indicate that BBR regulates gut microbiome homeostasis and controls mucosal inflammation to prevent CRC. In the CRC stage, BBR inhibits cell proliferation, invasion, and metastasis, blocks the cell cycle, induces cell apoptosis, regulates cell metabolism, inhibits angiogenesis, and enhances chemosensitivity. BBR plays a role in the overall management of CRC. Therefore, using BBR as an adjunct to CRC prevention and treatment could become a future trend in oncology.

Dynamic Interactions between Diarrhoeagenic Enteroaggregative Escherichia coli and Presumptive Probiotic Bacteria: Implications for Gastrointestinal Health

This study delves into the temporal dynamics of bacterial interactions in the gastrointestinal tract, focusing on how probiotic strains and pathogenic bacteria influence each other and human health. This research explores adhesion, competitive exclusion, displacement, and inhibition of selected diarrhoeagenic Escherichia coli (D-EAEC) and potential probiotic strains under various conditions. Key findings reveal that adhesion is time-dependent, with both D-EAEC K2 and probiotic L. plantarum FS2 showing increased adhesion over time. Surprisingly, L. plantarum FS2 outperformed D-EAEC K2 in adhesion and exhibited competitive exclusion and displacement, with inhibition of adhesion surpassing competitive exclusion. This highlights probiotics' potential to slow pathogen attachment when not in competition. Pre-infecting with L. plantarum FS2 before pathogenic infection effectively inhibited adhesion, indicating probiotics' ability to prevent pathogen attachment. Additionally, adhesion correlated strongly with interleukin-8 (IL-8) secretion, linking it to the host's inflammatory response. Conversely, IL-8 secretion negatively correlated with trans-epithelial electrical resistance (TEER), suggesting a connection between tight junction disruption and increased inflammation. These insights offer valuable knowledge about the temporal dynamics of gut bacteria interactions and highlight probiotics' potential in competitive exclusion and inhibiting pathogenic bacteria, contributing to strategies for maintaining gastrointestinal health and preventing infections.