Peroxiredoxin 1-mediated activation of TLR4/NF-κB pathway contributes to neuroinflammatory injury in intracerebral hemorrhage

The proinflammatory properties of extracellular peroxiredoxins (Prxs) via induction of Toll-like receptor 4 (TLR4) activation have been gradually revealed under diverse stress conditions, including cerebral ischemia but not hemorrhage. Prxl is proposed to be a major hemorrhagic stress-inducible isoform of Prxs during acute and subacute phases of intracerebral hemorrhage (ICH). However, the potential of Prxl in the neuroinflammatory injury after ICH remains unclear. This study investigated the proinflammatory effect and underlying mechanism of extracellular Prxl in cultured murine macrophages and a collagenase-induced mouse ICH model. The current results show that incubation of exogenous Prx1 (0-50 nM) with murine RAW264.7 macrophages resulted in increased expression of TLR4, nuclear translocation of nuclear factor KB (NF-kappa B) p65 and production of proinflammatory mediators (NO, TNF-a and IL-6) in a concentration-dependent manner. In addition, ICH induced murine neurological deficits, cerebral edema and neuropathological alterations, such as neuron injury, astrocyte and microglia/macrophage activation, and neutrophil and T lymphocyte invasion up to 72 h after ICH. Moreover, ICH stimulated Prxl expression and extracellular release, TLR4/NF-kappa B signaling activation, reflected by increases in TLR4 expression, extracellular signal-regulated kinase (ERIC) 1/2 and NF-kappa B activation, and production of cytokines (TNF-o:, IL-6 and IL-17). Taken together, these findings suggest that extracellular Prxl-mediated TLR4/NF-kappa B pathway activation probably contributes to neuroinflammatory injury after ICH, and thus blocking Prx1-TLR4 signaling might provide a novel anti-neuroinflammatory strategy with extended therapeutic window for hemorrhagic stroke. (C) 2016 Elsevier B.V. All rights reserved.