Protection from Hemolytic Uremic Syndrome by Eyedrop Vaccination with Modified Enterohemorrhagic E. coli Outer Membrane Vesicles

Abstract

We investigated whether eyedrop vaccination using modified outer membrane vesicles (mOMVs) is effective for protecting against hemolytic uremic syndrome (HUS) caused by enterohemorrhagic E. coli (EHEC) O157:H7 infection. Modified OMVs and waaJ-mOMVs were prepared from cultures of MsbB- and Shiga toxin A subunit (STxA)-deficient EHEC O157:H7 bacteria with or without an additional waaJ mutation. BALB/c mice were immunized by eyedrop mOMVs, waaJ-mOMVs, and mOMVs plus polymyxin B (PMB). Mice were boosted at 2 weeks, and challenged peritoneally with wild-type OMVs (wtOMVs) at 4 weeks. As parameters for evaluation of the OMV-mediated immune protection, serum and mucosal immunoglobulins, body weight change and blood urea nitrogen (BUN)/Creatinin (Cr) were tested, as well as histopathology of renal tissue. In order to confirm the safety of mOMVs for eyedrop use, body weight and ocular histopathological changes were monitored in mice. Modified OMVs having penta-acylated lipid A moiety did not contain STxA subunit proteins but retained non-toxic Shiga toxin B (STxB) subunit. Removal of the polymeric O-antigen of O157 LPS was confirmed in waaJ-mOMVs. The mice group vaccinated with mOMVs elicited greater humoral and mucosal immune responses than did the waaJ-mOMVs and PBS-treated groups. Eyedrop vaccination of mOMVs plus PMB reduced the level of humoral and mucosal immune responses, suggesting that intact O157 LPS antigen can be a critical component for enhancing the immunogenicity of the mOMVs. After challenge, mice vaccinated with mOMVs were protected from a lethal dose of wtOMVs administered intraperitoneally, conversely mice in the PBS control group were not. Collectively, for the first time, EHEC O157-derived mOMV eyedrop vaccine was experimentally evaluated as an efficient and safe means of vaccine development against EHEC O157:H7 infection-associated HUS.

Shiga-Toxin E. coli Hemolytic Uremic Syndrome: Review of Management and Long-term Outcome

“…A chimeric protein OmpA-LTB with the ability to bind against the intestinal wall when taken orally allows an immunogenic response to E. coli 0157:H7 to be mounted in silico [93•]. Targeting outer membrane vesicles (OMVs) produced by E. coli O157:H7 has been successfully explored using eyedrop administration in mice [94]. More recently, approaches targeting OMVs have also been tested in cattle and proved effective, providing encouraging results for future human use [95].…”

Lipopolysaccharide composition determines the preferred route and entry kinetics of bacterial outer membrane vesicles into host cells

“…We selected EHEC as a proof-of-concept species here, since EHEC OMVs have been shown to play a crucial role in toxin stabilization and delivery (Aldick et al, 2008), and have been considered as a means to vaccinate and protect against hemolytic uremic syndrome, a severe complication of EHEC infection (Choi et al, 2014). However, we expect the genetically encoded ClyA-Bla reporter would similarly be targeted to other Gram-negative species of interest, and this will be subject of further investigation to clarify if the herein identified surface features are equally important determinants in driving uptake of OMVs from other species.…”

HUS and the case for complement

“…These are uncovering potential strain-specific targets to reduce pathogen persistence, replication and adhesion, biofilm formation, and Stx invasion. 88 Closer to the clinic, vaccines and neutralizing anti-Stx antibodies are in development, [89][90][91] and these will hopefully reduce the incidence and severity of STEC-HUS. …”