Contribution of polyunsaturated fatty acids to Shiga toxin cytotoxicity in human renal tubular epithelium-derived cells.

Shiga toxin (Stx) produced by enterohemorrhagic Escherichia coli is a critical factor in the onset of hemolytic uremic syndrome. The current study was designed to assess whether n-3 and (or) n-6 polyunsaturated fatty acids (PUFA) act as a valuable adjunct to prevent the cell injury of renal tubule cells in the emergence of HUS. The target cells, ACHN cells derived from human tubule epithelium, were cultured with each PUFA, then exposed to Stx-1 or Stx-2. The rank order of potency of PUFA to inhibit the cell death caused by each toxin was as follows: EPA > AA = DHA >> LNA. There were dose-response relations in the efficacy of each PUFA. No prophylactic effect was found in the cultures with LA. Immunofluorescence assays revealed that both the expression of the toxin receptor on ACHN cells and binding between the toxin and cells were unaffected by the PUFA. These results suggest that EPA is the most efficacious PUFA against the renal tubule cell injury caused by Stx, which may be assigned to an alteration in the intracellular pathway leading to cell death.

Protective effect of anisodamine against Shiga toxin-1: inhibition of cytokine production and increase in the survival of mice.

The purpose of this study was to investigate whether anisodamine could inhibit Shiga toxin-1 (Stx1)-induced cytokine production and increase the survival of Stx1-treated mice. Human monocytic cells were stimulated by Stx1 (1 to 100 ng/mL) with or without anisodamine addition (1 to 400 microg/mL). For in vivo evaluations, C57BL/6 mice were given a single intraperitoneal injection of anisodamine (1 mg) or saline solution after intraperitoneal injection of Stx1 (2.75 microg/kg). The results showed that anisodamine significantly suppressed Stx1-induced tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-8 production. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that anisodamine suppressed Stx1-mediated TNF-alpha mRNA expression. Further study showed that this TNF-alpha inhibitory effect was via a prostaglandin E2-dependent mechanism. Anisodamine treatment prolonged the survival time of mice and decreased the lethality of Stx1 (94.5% to 44%). Because cytokines, in particular TNF-alpha, contribute to the pathologic process in Stx-producing Escherichia coli (STEC) infection, this study suggested that anisodamine could be a potential drug for treatment of STEC infection.