The effects of Escherichia coli Nissle and Salmonella typhimurium bacterial ghosts
on human conjunctival epithelial cells

Abstract

Purpose : Bacterial ghosts (BGs) are empty cell envelopes derived from Gram-negative bacteria. BGs possess all cell membrane structures, like live bacteria they are originated from, which gives a potential to use them as an adjuvant delivery system. In the present study, we investigated the potential of Escherichia coli Nissle (EcN) and Salmonella typhimurium (Sty) BGs in modulation of immune responses in human conjunctival epithelial cells (HCjE).

Methods : Confluent monolayers of HCjE cells were treated for 2 and 24 hours with EcN and Sty BGs at a concentration of 1x10⁸ particles/ml, as well as with Interleukin- 1α as a general stimulator. 24 hours after cell stimulation the supernatants and cells were collected. Concentration of IL-6 and IL-8 were measured using ELISA. Quantification of the gene expression levels for TLR-4 and TLR-5 was performed using qRT-PCR.

Results : HCjE cells responded to EcN BGs and Sty BGs with increased secretion of pro-inflammatory cytokines and expression of toll-like receptors (TLRs). Expression of TLR-4 and TLR-5 was significantly higher in EcN BGs stimulated cells compared to Sty BGs stimulated HCjE cells (P<0.05). EcN and Sty BGs induced enhanced secretion of IL-6 and IL-8 in HCjE cells.

Conclusions : Our results suggest that both used BGs may modulate the secretion of IL-6 and IL-8 mainly via the activation of TLR-4 and TLR-5 in HCjE cells.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.