Escherichia coli Nissle 1917 bacterial ghosts retain crucial surface properties and express chlamydial antigen: an imaging study of a delivery system for the ocular surface

Abstract

To target chronic inflammatory ocular surface diseases, a drug delivery platform is needed that is safe, possesses immunomodulatory properties, and can be used either for drug delivery, or as a foreign antigen carrier. A new therapeutic approach that we have previously proposed uses nonliving bacterial ghosts (BGs) as a carrier-delivery system which can be engineered to carry foreign antigens and/or be loaded with therapeutic drugs. The parent strain chosen for development of our BG delivery system is the probiotic Escherichia coli strain Nissle 1917 (EcN), whose intrinsic properties trigger the innate immune system with the flagella and fimbriae used to attach and stimulate epithelial cells. In previous studies, we have shown that EcN BGs are safe for the ocular surface route, but evidence that EcN BGs retain flagella and fimbriae after transformation, has never been visually confirmed. In this study, we used different visualization techniques to determine whether flagella and fimbriae are retained on EcN BGs engineered either for drug delivery or as a foreign antigen carrier. We have also shown by immunoelectron microscopy that EcN retains two foreign antigens after processing to become EcN BGs. Furthermore, we demonstrated that BGs derived from EcN and expressing a foreign antigen attachment to conjunctival epithelial cells in vitro without causing reduced cell viability. These results are an important step in constructing a delivery system based on a nonliving probiotic that is suitable for use in ocular surface diseases pairing immunomodulation and targeted delivery.

Subcutaneous Immunization of Dogs With Bordetella bronchiseptica Bacterial Ghost Vaccine

“…It is due to this role that in some of the acellular pertussis (aP) vaccines fim2 and fim3 have been included (71). Fimbriae and pili are well preserved in BGs, and are part of vaccine preparations as shown with toxin co-regulated pili in Vibrio cholera BGs and fimbriae in E. coli BGs (37, 72). However, the presence of fimbriae in the BbBGs has not been investigated in current study and needs to be proved before any conclusions are extrapolated.…”

Bacterial Ghosts-Based Vaccine and Drug Delivery Systems

“…Barisani Asenbauer et al cultured E. coli in a fermentor until OD600 = 0.9, which took about 90 min. Under temperature-sensitive expression systems, a temperature of 42 • C induces the expressions of protein E. After 120 min of expression, lytic efficiency reached 99.9% [31]. Langemann et al prepared BGs by heating a mixed culture media of bacteria to 42 • C. After 2 h, bacterial lytic efficiency reached 99.99% [21].…”

“…Clostridium difficile [65] and polymeric flagellin filaments are examples of flagella-based vaccines [66]. The flagellum structure on BGs remains intact [31]. Flagellin can induce the expressions of TLR5 and Nod-like receptor card domain containing 4 (NLRC4) inflammasomes' signaling pathways [67,68].…”

Peer Review #1 of "Improved ultrastructure of marine invertebrates using non-toxic buffers (v0.1)"

“…(Supplementary figure 4). A more diluted formulation (2.5% GA in 0.06X PHEM) was used for investigating the terrestrial soil archaea Nitrososphaera viennensis (Stieglmeier et al 2014) as well as E. coli (Montanaro et al 2015) and a 1X PHEM formulation without sucrose was used for the fixation of the limnic flatworm Stenostomum cf. leucops.…”