AbstractShiga toxin 2 (Stx2) from enterohemorrhagic Escherichia coli (EHEC) produces hemorrhagic colitis, hemolytic uremic syndrome (HUS) and acute encephalopathy. The mortality rate in HUS increases significantly when the central nervous system (CNS) is involved. Besides, EHEC also releases lipopolysaccharide (LPS). Many reports have described cognitive dysfunctions in HUS patients, the hippocampus being one of the brain areas targeted by EHEC infection. In this context, a translational murine model of encephalopathy was employed to establish the deleterious effects of Stx2 and the contribution of LPS in the hippocampus. Results demonstrate that systemic administration of a sublethal dose of Stx2 reduced memory index and produced depression like behavior, pro-inflammatory cytokine release and NF-kB activation independent of the ERK 1/2 signaling pathway. On the other hand, LPS activated NF-kB dependent on ERK 1/2 signaling pathway. Cotreatment of Stx2 with LPS aggravated the pathologic state, while dexamethasone treatment succeeded in preventing behavioral alterations. Our present work suggests that the use of drugs such as corticosteroids or NF-kB signaling inhibitors may serve as neuroprotectors from EHEC infection.Author SummaryShiga toxin (Stx) from enterohemorrhagic Escherichia coli (EHEC) is one of the most virulent factors responsible for hemolytic uremic syndrome (HUS). Stx2, the endemic variant targets the brain, among other organs, thus inducing encephalopathies. Central nervous system (CNS) compromise was the main predictor of death in patients with HUS. Stx2 may exert a direct action in the CNS, by disrupting the neurovascular unit. In this context, we investigate the molecular signaling triggered by Stx2 in the murine brain hippocampus involved in inflammatory mechanisms that altered hippocampal-related cognitive behaviors. The present data underscore that the use of drugs such as dexamethasone or those blocking the cascade by preventing NF-kB translocation to the nucleus may serve as effective neuroprotectors with potentially beneficial use in the clinic.
Cognitive deficits found in a pro-inflammatory state are independent of ERK 1/2 signaling in the murine brain hippocampus treated with Shiga toxin 2 from enterohemorrhagic Escherichia Coli
