Enhancement of Susceptibility to Shiga Toxin-Producing Escherichia coli O157:H7 by Protein Calorie Malnutrition in Mice

Abstract

Infection with Shiga toxin (Stx)-producing enterohemorrhagicEscherichia coli is increasing among children. In this study, 5-week-old C57BL/6 mice with protein calorie malnutrition (PCM) that had been fed a 5% protein diet for 2 weeks since ablactation were inoculated intragastrically with 2 × 106 CFU of Stx-producing E. coli O157:H7. More than 75% of infected mice with PCM died by 10 days postinfection. Infected mice with PCM developed neurologic symptoms 5 days after infection, while well-nourished control mice receiving a 25% protein diet did not. In the intestinal tracts of infected mice with PCM, inoculated E. coli O157:H7 multiplied between days 2 and 4 of infection, with a peak of growth at day 4. Although the pathogens were not culturable from the stool after day 7, O157 lipopolysaccharide was detectable in the stool by enzyme-linked immunosorbent assay even after day 8. Stx was detectable in the stool after day 2 of infection and increased in proportion to the growth of inoculated organisms. The maximal production of Stx occurred at 4 days postchallenge, and Stx was detectable in the blood on days 3 to 5. In contrast, well-nourished control mice survived the infection, and all of them remained well even after 3 weeks of infection. In these control mice, inoculated E. coli O157:H7 disappeared from the stool before day 3. Stx was not detectable in the stool and blood of infected control mice at any time from day 1 through day 8. Histologically, cerebral hemorrhages seemed to be the cause of acute death of infected mice with PCM. Immunocytochemical staining demonstrated the positive immunoreaction to Stx at the alveus and stratum pyramidale of the hippocampus and in renal tubules of infected malnourished mice. Such immunoreactions were not found in tissues from infected control mice. Histological study of the intestinal epithelium before infection showed that PCM severely affected the development of intestinal epithelia. These findings strongly indicate that PCM-induced nondevelopment of intestinal physical barrier is one of the predisposing factors for infection with Stx-producing E. coli O157:H7 in mice and suggest that our mouse model may explain the high incidence of infection with Stx-producing E. coli O157:H7 in the children whose intestinal epithelia have not yet completely developed.

Renal damage and death in weaned mice after oral infection with Shiga toxin 2-producing Escherichia coli strains

“…Immaturity includes a non-specific defence system along with a mucosal adaptive immune system not fully developed, so that the physical barrier of intestinal epithelia has an increased permeability in comparison with adult mice. Similarly, Kurioka et al suggested that, in malnourished adult mice, permeability of epithelia is increased, and therefore it is possible that not only Stx but also lipopolysaccharide (LPS) O157 is absorbed through the intestinal epithelia in both models [18]. It has been largely reported that LPS increases the in vitro and in vivo cytotoxic effects of Stx.…”

“…Renal damage in weaned mice fed with Stx-producing bacteria would indicate that the toxin has reached systemic circulation, and the close association between high urea levels, prompt neutrophilia and death suggests that kidney is On the other hand, in the malnourished model mice died after 6 days of oral E. coli O157:H7 infection with signs of neurological but not renal injury [17,18]. Similarities between both, malnourished and weaned mouse models, such as the incomplete development of intestinal epithelia and mucosal immune response, can account for the Stx passage to circulation, and consequently systemic complications.…”

Dextran Sulfate Sodium Colitis Facilitates Colonization with Shiga Toxin-Producing Escherichia coli: a Novel Murine Model for the Study of Shiga Toxicosis

“…Systemic circulation of Shiga toxins induces renal tubular injury in mice, but standard laboratory strains of naive mice are resistant to gastrointestinal colonization by STEC (18,19). Previous approaches to induce susceptibility to STEC colonization include severe protein restriction, high-dose antibiotic treatment, and germ-free conditions (17,(20)(21)(22). Colonization may follow, but these models have proven difficult to reproduce, the commensal microbiome is grossly ablated, and germ-free conditions are not generalizable due to altered host responses to pathogens in the absence of host-microbiota interactions (2).…”

The Path physiology of Renal Failure in a Shiga Toxin plus Lipopolysaccharide Induced Murine Model of Hemolytic Uremic Syndrome

“…In contrast to rabbits, mice and rats given Stx or STEC do not consistently develop diarrhea, colitis or A/E lesions, however they do demonstrate some renal and neurologic pathology 85,412 . Numerous mouse strains have been tested, including C57BL6, CD-1, C3H/HeN, C3H, HeJ, and BALB/c, and the results are comparable between strains 94,116,119,394,[398][399][400][401][402][403][404][405][406][407][408][409][410][411][412][413]427 . Rat strains used include Sprague-Dawley and Wistar, and again the results are relatively equivalent between strains 394,[414][415][416] .…”

“…Grossly, Gb3 staining and Stx targeting is seen in all three main murine renal compartments, the cortex medulla and papilla, however the specific cellular localization is disagreed upon 94,116 . One group of reports describe toxin binding to and Gb 3 expression on subsets of proximal, distal, and collecting duct tubular cells within the renal parenchyma 94,116,408,410,414,427,435 . Other publications demonstrate Stx interaction with or Gb 3 expression on glomeruli, the renal vasculature, and other vascular cells [398][399][400] .…”