Surface display of PbrR on Escherichia coli and evaluation of the bioavailability of lead associated with engineered cells in mice

Abstract

Human exposure to lead mainly occurs by ingestion of contaminated food, water and soil. Blocking lead uptake in the gastrointestinal tract is a novel prevention strategy. Whole-cell biosorbent for lead was constructed with PbrR genetically engineered on the cell surface of Escherichia coli (E. coli), a predominant strain among intestinal microflora, using lipoprotein (Lpp)-OmpA as the anchoring protein. In vitro, the PbrR displayed cells had an enhanced ability for immobilizing toxic lead(II) ions from the external media at both acidic and neutral pH, and exhibited a higher specific adsorption for lead compared to other physiological two valence metal ions. In vivo, the persistence of recombinant E. coli in the murine intestinal tract and the integrity of surface displayed PbrR were confirmed. In addition, oral administration of surface-engineered E. coli was safe in mice, in which the concentrations of physiological metal ions in blood were not affected. More importantly, lead associated with PbrR-displayed E. coli was demonstrated to be less bioavailable in the experimental mouse model with exposure to oral lead. This is reflected by significantly lower blood and femur lead concentrations in PbrR-displayed E. coli groups compared to the control. These results open up the possibility for the removal of toxic metal ions in vivo using engineered microorganisms as adsorbents.

Oral lichen planus and other confounding factors in narrow band imaging (NBI) during routine inspection of oral cavity for early detection of oral squamous cell carcinoma: a retrospective pilot study

“…In our retrospective study, we assessed NBI efficacy in routine clinical use, on a cohort of patients affected by oral lesions, not normalized for possible bias suggested by present literature. This led to differences respect to data shown by literature, in which the specificity is usually higher than the sensitivity and, in general, oral cavity lesions are often grouped with oropharynx lesions and sometimes with laryngeal/nasopharyngeal lesions too [9, 10]. In order to acknowledge the OLP influence as a possible bias, we performed every statistical calculation with and without OLP patients.…”

“…NBI has proved remarkably positive results: when IPCL pattern III and IV are detected, literature showed a high correlation to OSCC/Cis/HGD [9, 10, 12, 13]. Yet, studies generally exclude OPMDs, especially OLP, as they are considered major bias [9–11]. These lesions often have dishomogeneous/ulcerated aspects and show high-grade NBI patterns.…”

“…NBI, by allowing enhanced inspection of shallow vascular structures of the superficial mucosal layers, has shown its effectiveness for detection of dysplastic/cancerous lesions of the upper aero-digestive tract: oral cavity, oro- and hypopharynx, larynx, esophagus [1–8]. In a recent meta-analysis [9] assessing NBI capability to detect head & neck squamous cell carcinoma (HNSCC), the calculated specificity, sensitivity, negative likelihood rate, positive likelihood rate, and diagnostic odds ratio (OR) of NBI were 95.6, 88.5%, 0.11, 12.33, and 121.26, respectively. Different systems for classifying patterns of intraepithelial capillary vessels (intraepithelial papillary capillary loop, IPCL) have been identified, related to increasing grades of dysplasia/neoplasia of oral cavity [1–4, 6, 8].…”

“…Despite these excellent results, routine clinical use in the inspection of oral cavity may present some difficulties. Many studies often exclude Oral Potentially Malignant Disorders (OPMDs), as they are considered confounding factors [9], especially in case of patients with Oral Lichen Planus (OLP) [9–11] due to the dishomogeneous/ulcerated aspect of the lesions and the correlation with high-grade NBI patterns. The site of the lesion is sometimes considered as bias too, due to different types of epithelium found in oral cavity; usually, epithelium of the oral cavity is classified into four categories, namely: lining epithelium (non-keratinized; e.g.…”

Rapid monitoring of the target protein expression with a fluorescent signal based on a dicistronic construct in Escherichia coli

“…Escherichia coli expression host BL21(DE3)pLysS or Rosetta(DE3)pLysS was transformed with recombinant vectors using a CaCl 2 -mediated transformation method (Hui et al 2018a ). The transformed E. coli cells were spread on LB agar plates containing 50 μg/mL ampicillin and 34 μg/mL chloramphenicol, and then cultured overnight at 37 °C.…”