EspA-loaded mesoporous silica nanoparticles can efficiently protect animal model against enterohaemorrhagic E. coli O157: H7.

In the present study, the application of mesoporous silica nanoparticles (MSNPs) loaded with recombinant EspA protein, an immunogen of enterohaemorrhagic E. coli, was investigated in the case of BALB/c mice immunization against the bacterium. MSNPs of 96.9 ± 15.9 nm in diameter were synthesized using template removing method. The immunization of mice was carried out orally and subcutaneously. Significant immune responses to the antigen were observed for the immunized mice when rEspA-loaded MSNPs were administered in both routes in comparison to that of the antigen formulated using a well-known adjuvant, i.e. Freund's. According to the titretitre of serum IL-4, the most potent humoral responses were observed when the mice were immunized subcutaneously with antigen-loaded MSNPs (244, 36 and 14 ng/dL of IL-4 in the serum of mice immunized subcutaneously or orally by antigen-loaded MSNPs, and subcutaneously by Freund's adjuvant formulated-antigen, respectively). However, the difference in serum IgG and serum IgA was not significant in mice subcutaneously immunized with antigen-loaded MSNPs and mice immunized with Freund's adjuvant formulated-antigen. Finally, the immunized mice were challenged orally by enterohaemorrhagic E. coli cells. The amount of bacterial shedding was significantly reduced in faecesfaeces of the animals immunized by antigen-loaded MSNPs in both subcutaneous and oral routes.

Butyrate upregulates endogenous host defense peptides to enhance disease resistance in piglets via histone deacetylase inhibition.

Butyrate has been used to treat different inflammatory disease with positive outcomes, the mechanisms by which butyrate exerts its anti-inflammatory effects remain largely undefined. Here we proposed a new mechanism that butyrate manipulate endogenous host defense peptides (HDPs) which contributes to the elimination of Escherichia coli O157:H7, and thus affects the alleviation of inflammation. An experiment in piglets treated with butyrate (0.2% of diets) 2 days before E. coli O157:H7 challenge was designed to investigate porcine HDP expression, inflammation and E. coli O157:H7 load in feces. The mechanisms underlying butyrate-induced HDP gene expression and the antibacterial activity and bacterial clearance of macrophage 3D4/2 cells in vitro were examined. Butyrate treatment (i) alleviated the clinical symptoms of E. coli O157:H7-induced hemolytic uremic syndrome (HUS) and the severity of intestinal inflammation; (ii) reduced the E. coli O157:H7 load in feces; (iii) significantly upregulated multiple, but not all, HDPs in vitro and in vivo via histone deacetylase (HDAC) inhibition; and (iv) enhanced the antibacterial activity and bacterial clearance of 3D4/2 cells. Our findings indicate that butyrate enhances disease resistance, promotes the clearance of E. coli O157:H7, and alleviates the clinical symptoms of HUS and inflammation, partially, by affecting HDP expression via HDAC inhibition.

Neutralizing activity of bovine colostral antibody against verotoxin derived from enterohemorrhagic Escherichia coli O157:H7 in mice.

The neutralization efficacy of bovine colostral antibody against verotoxin (VT) 1 and 2 was investigated. Cows were immunized with VT1 or VT2 fourteen times at 7-day intervals. A colostral antibody exhibiting high titers was obtained from immunized cows. Survival rates were evaluated in mice administered VT1 or VT2, and those infected with Escherichia coli (E. coli) O157:H7 producing VT1 or VT2. Survival rates after VT1 administration were 100% in the single-administration group, 90% in the repeat-administration group, and 78.6% in the control group. Survival rates after VT2 were 75.0% in the single-administration group, and 100% in the repeat-administration group. All mice in the control group died. Colostral antibody and fosfomycin (FOM) in the colostral antibody group and FOM and skim milk in the control group were administered three times per day for 5 days to mice infected with E. coli O157:H7 producing VT1 or VT2. Survival rates after inoculation with E. coli O157:H7 producing VT1 were 80.0% in the colostral antibody group, and 63.6% in the control group. Survival rates after inoculation with E. coli O157:H7 producing VT2 were 83.3% in the colostral antibody group, and 20.0% in the control group. The survival rate in mice without treatment following inoculation with E. coli O157:H7 producing VT2 was 88.2%. The survival rates in mice infected with E. coli O157:H7 strains producing VT1 or VT2 improved after administration of this colostral antibody, which exhibited neutralization efficacy against VT.

A standard immunoglobulin preparation produced from bovine colostra shows antibody reactivity and neutralization activity against Shiga-like toxins and EHEC-hemolysin of Escherichia coli O157:H7.

Enterohemorrhagic Escherichia coli (EHEC) causes a variety of clinical conditions, the most important being hemorrhagic colitis and hemolytic uremic syndrome. A curative therapy of EHEC diseases is not yet feasible. This study investigates the antibody reactivity of Lactobin, a standardized immunoglobulin (Ig) preparation, obtained from the colostra of non-immunized cows. Three different batches of Lactobin exhibited equally high titers of specific antibodies against Shiga-like toxins (SLTs, verocytotoxins) and EHEC hemolysin (EHEC-Hly) produced by E. coli O157. In addition, Lactobin blocked the cytotoxic effect of SLT-I and SLT-II on Vero cell monolayers and inhibited the cytolytic effects of EHEC-Hly on human erythrocytes. Since Lactobin contains high levels of antibodies and neutralizing activity against important virulence factors of EHEC O157, this drug has potential use in the treatment of diarrhea and the prevention of EHEC-associated hemolytic uremic syndrome.