Direct evidence of neuron impairment by oral infection with verotoxin-producing Escherichia coli O157:H- in mitomycin-treated mice

Abstract

We developed a mouse model of acute encephalopathy induced by verotoxin 2 variant (VT2v)-producing Escherichia coli. Three-week-old mice were inoculated intragastrically with approximately 10(10) CFU of E. coli O157:H- strain E32511/HSC and simultaneously given an intraperitoneal injection of mitomycin (MMC; 2.5 mg/kg). Drinking water containing 5 g of streptomycin sulfate per liter was given ad libitum from 3 days before the infection. From 1 to 2 days after bacterial inoculation, clinical features including weight loss, weakness, and flaccid paralysis of the extremities developed, usually culminating in death within 4 days. Diarrhea was not observed during the course of disease. No mice died in the absence of streptomycin or MMC treatment for 2 weeks after the oral bacterial infection. Judging from the clinical course and the biochemical and histological examination, the cause of death was not likely to be attributable to renal failure or to a side effect of MMC. To better understand the cause of death, we examined the brain cortex and spinal cord of the moribund mice by electron microscopy. Mice showing mortal symptoms were given horseradish peroxidase intravenously. The tracer was present in the endothelial basal lamina, in the surrounding extracellular spaces, and even in the neuron fibers of the brain cortex. Furthermore, immunoreactivity of VT2v, proved by the use of rabbit anti-VT2 serum, was localized selectively in the damaged myelin sheaths of neuron fibers which were accompanied by edematous axons in the brain cortex and spinal cord. These findings strongly suggest that VT2v is toxic to both endothelial cells and neurons in the central nervous system and subsequently causes fatal acute encephalopathy.

Risk factors for neurological complications in complete hemolytic uremic syndrome caused by Escherichia coli O157

“…15 Fujii et al , however, reported that vero toxin (VT) 2 was toxic directly to both endothelial cells and neurons in mitomycin-treated mice irrespective of the deterioration of renal function. 16 In the present study we found that an average daily increase of serum LDH and creatinine levels were useful to predict neurological abnormalities in complete HUS patients. The present data might suggest that the deterioration rate of renal function was linked to the pathogenesis of neurological abnormalities in patients with complete HUS caused by E.coli O157, although an accelerated average daily increase of serum LDH indicated also a refl ection of tissue damage, including to the blood vessels of the brain.…”

MRI Findings of Hemolytic Uremic Syndrome With Encephalopathy: Widespread Symmetrical Distribution

“…Fujii et al proved that verotoxin impairs B B B in a mouse model of acute encephalopathy induced by infection with VTEC and that myelin sheath destruction and axonal edema were caused by the direct cytotoxic effect of verotoxin. 11,12 So, the possibility exists that local breakdown of BBB caused by verotoxin produced the edema and widespread lesion like ANE in our case. Gadolinium enhancement in acute stage and elevation of myelin basic protein in CSF may support the impairment of BBB and myelin sheath destruction caused by verotoxin.…”

Chemotherapy for enterohemorrhagic Escherichia coli O157:H infection in a mouse model

“…Although the e¡ect of antimicrobial agents on EHEC in vitro has been reported [9,10,19], the therapeutic e¡ect of antimicrobial agents on EHEC infected animals has yet to be reported. Previously we have established the mouse model with EHEC E32511/HSC strain [13]. In our mouse model, a large amount of EHEC (10 9 CFU) was inoculated and the release of VT2c was increased by MMC injection.…”

“…In this study, we used a mouse model with EHEC given orally and mitomycin C (MMC) intraperitoneally [13]. It has been reported that VT production by EHEC is increased in vitro by the addition of MMC to the culture, possibly as a result of the phage induction [14,15].…”