Recombinant high-mobility group box 1 protein (HMGB-1) promotes myeloid differentiation primary response protein 88 (Myd88) upregulation in mouse primary cortical neurons

Abstract

Myeloid differentiation primary response protein 88 (Myd88) is a vital factor for inflammation and immunity, and high-mobility group box 1 protein (HMGB-1) can be released from neurons after injury and may contribute to the initial stages of inflammatory response. Therefore, the current study was intended to investigate the expression of Myd88 in cultured neurons following recombinant HMGB-1 (rHMGB-1) addition and to clarify the potential role of Myd88 after neuron injury in vitro. The cultured neurons were randomly divided into six groups: control group and rHMGB-1 groups at hours 1, 6, 12, 24, and 48. The cultured neurons in rHMGB-1 groups were subjected to rHMGB-1 addition. The expression of Myd88 was assessed by quantitative real-time polymerase chain reaction (PCR), Western blotting and immunofluorescence, and nuclear factor kappa B (NF-κB) DNA-binding activity was detected by electrophoretic mobility shift assay, and the levels of tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) were measured by quantitative real-time PCR. The elevated mRNA and protein levels of Myd88, peaking at 24 h, were detected after rHMGB-1 addition. NF-κB, TNF-α, and IL-1β also ascended significantly after rHMGB-1 addition. Interestingly, Myd88 increasingly expressed in a parallel time course to the upregulation of NF-κB, TNF-α, and IL-1β. These findings indicated a possible role of Myd88 in the inflammatory response after neuron injury, and might provide an attractive therapeutic approach of targeting the Myd88 cascade to achieve better outcomes for patients with central nervous system injury.