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ACS Chem Neurosci. 2019 Mar 20;10(3):1273-1283. doi: 10.1021/acschemneuro.8b00354. Epub 2018 Nov 15.

Stimulations of the Culture Medium of Activated Microglia and TNF-Alpha on a Scrapie-Infected Cell Line Decrease the Cell Viability and Induce Marked Necroptosis That Also Occurs in the Brains from the Patients of Human Prion Diseases.

Author information

1
State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases (Zhejiang University), National Institute for Viral Disease Control and Prevention , Chinese Center for Disease Control and Prevention , Chang-Bai Rd 155 , Beijing 102206 , China.
2
Center of Global Public Health , Chinese Center for Disease Control and Prevention , Chang-Bai Rd 155 , Beijing 102206 , China.

Abstract

Activation of microglia and increased expression of TNF-α are frequently observed in the brains of human and animal prion diseases. As an important cytokine, TNF-α participates in not only pro-inflammatory responses but also in cellular communication, cell differentiation, and cell death. However, the role of TNF-α in the pathogenesis of prion disease remains ambiguous. In this study, the activities of a scrapie-infected cell line SMB-S15 and its normal partner SMB-PS exposed to the supernatant of a LPS-activated microglia cell line BV2 were evaluated. After it was exposed to the LPS-stimulated supernatant of BV2 cells, the cell viability of SMB-S15 cells was markedly decreased, whereas that of the SMB-PS cells remained unchanged. The level of TNF-α was significantly increased in the LPS-stimulated supernatant of BV2 cells. Further, we found that the recombinant TNF-α alone induced the decreased cell viability of SMB-S15 and the neutralizing antibody for TNF-α completely antagonized the decreased cell viability caused by the LPS-stimulated supernatant of BV2 cells. Stimulation with TNF-α induced the remarkable increases of apoptosis-associated proteins in SMB-PS cells, such as cleaved caspase-3 and RIP1, whereas an obvious increase of necroptosis-associated protein in SMB-S15 cells, such as p-MLKL. Meanwhile, the upregulation of caspase-8 activity in SMB-PS cells was more significant than that of SMB-S15 cells. The decreased cell viability of SMB-S15 and the increased expression of p-MLKL induced by TNF-α were completely rescued by Necrostatin-1. Moreover, we verified that removal of PrPSc propagation in SMB-S15 cells by resveratrol partially rescues the cell tolerance to the stimulation of TNF-α. These data indicate that the prion-infected cell line SMB-S15 is more vulnerable to the stimulations of activated microglia and TNF-α, which is likely due to the outcome of necroptosis rather than apoptosis. Furthermore, significant upregulation of p-MLKL, MLKL, and RIP3 was detected in the post-mortem cortical brains of the patients of various types of human prion diseases, including sporadic Creutzfeldt-Jakob disease (sCJD), G114 V-genetic CJD (gCJD), and fatal familial insomnia (FFI).

KEYWORDS:

Prion; TNF-alpha; apoptosis; microglia; necroptosis; scrapie

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