An Interventional Approach to Block Brain Damage Caused by Shiga Toxin–ProducingEscherichia coliInfection, by Use of a Combination of Phosphodiesterase Inhibitors

Abstract

We tested the combination of phosphodiesterase (PDE) 3 and PDE4 inhibitors as an interventional approach to prevent the development of brain damage after Shiga toxin (Stx)-producing Escherichia coli (STEC) infection, using mice with protein calorie malnutrition. The combination consisted of pentoxifylline and rolipram; the dose of each inhibitor was 7.5 mg/kg. Treatment with this combination, which was administered intraperitoneally twice daily at 12-h intervals, increased serum concentrations of each inhibitor to >2 microg/mL and afforded significant levels of protection when it was continued for 3 days, starting on day 2 (95% survival rate; P<.001) or day 3 (63% survival rate; P<.01) of infection. The treatment reduced plasma levels of Stx2; consequently, immunoreactions of Stx2 were not found in the brain, and survivors did not show neurologic symptoms. Protection was associated with decreased levels of tumor necrosis factor (TNF)- alpha and increased production of interleukin-10 in serum, the brain, and the cecum. Although the combination at doses >2 microg/mL reduced Gb3 content of and Stx2 binding to Caco-2 cells, its ability to suppress production of TNF- alpha seemed to be more important for the decrease in cell-bound Stx2 in intestinal epithelial cells. Therefore, the combination of PDE3 and PDE4 inhibitors might be used as an interventional approach to prevent brain damage caused by STEC infection.

Shiga Toxin 1-Induced Inflammatory Response in Lipopolysaccharide-Sensitized Astrocytes Is Mediated by Endogenous Tumor Necrosis Factor Alpha

“…The in vivo relevance of our findings is supported by data from studies where the local production of TNF-␣ in mouse brains after STEC infection was previously described, although the cellular source has not been determined (30). Moreover, it was reported previously that microinjection of TNF-␣ in the brain induces PMN accumulation and adherence to blood vessels (26).…”

“…LPS triggers a signaling cascade that results in the activation and nuclear translocation of the transcription factor NF-B that regulates proinflammatory genes including TNF-␣ family members (30). In addition, following damage to the central nervous system (CNS), many processes occurring in reactive ASTs are regulated largely by NF-B.…”

Mapping of genetic loci that modulate differential colonization by Escherichia coli O157:H7 TUV86-2 in advanced recombinant inbred BXD mice

“…Use of Pde4a-specific inhibitors has anti-inflammatory effects, such as reduced neutrophil adhesion [ 59 ] and inhibition of cellular trafficking and microvascular leakage [ 60 ]. Additionally, Pde4 inhibitors have been proposed to prevent STEC-mediated brain damage [ 61 ]. Panx1 is part of the innexin family, and as such a structural component of gap junctions [ 49 ] Panx1 is responsible for the release of ATP to the extracellular space, which can initiate cellular migration and inflammation [ 62 ].…”

Shiga Toxin 1 Induces on Lipopolysaccharide-Treated Astrocytes the Release of Tumor Necrosis Factor-alpha that Alter Brain-Like Endothelium Integrity

“…Although the astrocytic inflammatory response elicited by Stx in vivo or in HUS patients has not been studied until the moment, there are two reports in the literature using animal models that demonstrated ASTs activation and alteration after Stx inoculation [33], [34]. In addition, local production of TNF-α has been described in mouse brains after STEC infection [35]. We have recently demonstrate that Stx1 exerts a direct action on rat ASTs, although sensitization with LPS potentiates Stx1-induced effects, by means of increasing Gb3 expression, revealing activation of ASTs and the development of an inflammatory response characterized by the secretion of nitric oxide (NO), TNF-α and chemokines that promote PMN attraction.…”