神經發炎調控α-synuclein蛋白堆積之研究

Abstract

巴金森氏症(Parkinson’s disease)為最常見的神經退化性疾病之一。其特徵在於神經元內α-synuclein堆積路易士體(Lewy bodies)導致多巴胺神經退化。鑑於類鐸受體 (Toll-like receptors, TLRs)為先天免疫系统的第一道防线。根據報導，TLR 會促進神經發炎和a-synuclein之堆積而引發巴金森氏症，然而詳細機制仍未知。膠質細胞（RFP-HMC）受LPS刺激後,與神經細胞(SNCA-GFP-SHSY5Y)共同培養。 神經細胞的neurites會縮短並增加了α-synuclein之堆積， TLR 2，4，5，7和9，P-α-synuclein和P-JNK / P-p38的表現增加。TLR 2，TLR 4，JNK / p38抑制劑可減少a-synuclein之堆積和P -α-synuclein。我們進一步研究腸道微生物的代謝物，Short-chain fatty acids (SCFA) 對膠質細胞的影響，發現會活化 MAPK和NFkB ，表示SCFAs可能引發發炎反應。膠質細胞受SCFAS刺激後，與神經細胞共同培養，也會縮短neurites和增加α-synuclein之堆積，增加神經的TLR 2，TLR4和P-JNK / P-p38的表現。因此，LPS和SCFAs引發之神經發炎，會增加神經細胞的TLR 2/4進經由活化JNK / p38調控α-synuclein之堆積和磷酸化

Parkinson’s disease (PD) is the second most common neurodegenerative disorder in the world, and is characterized by intraneuronal α-synuclein aggregations resulting in the loss of dopaminergic neurons. Toll-like receptors (TLRs) are the first line defense of innate immune system, and were reported to be involved in the pathogenesis of PD by promoting neuroinflammation and α-synuclein aggregation. However, the underlying mechanism is not still elusive. Microglia-neuron co-culture system was employed in the current study. Microglial cells (RFP-HMC) were stimulated by LPS then co-cultured with stably transfected α-synuclein neuronal cells (SNCA-GFP-SHSY5Y). Shortening of neurites and the increase of intra-neuronal α-synuclein aggregation were observed after co-culture, and the expression of neuronal TLR 2,4,5,7, and 9, phospho-α-synuclein and P-JNK/P-p38 was also elevated. In addition, the inhibitors of TLR2, TLR4 and JNK/p38 reduced neuronal α-synuclein aggregation and phosphorylation, while maintained total α-synuclein. We further investigate the effect of gut microbiota metabolites short-chain fatty acid (SCFAs) on microglia cells and showed to activation of MAPK and NFkB pathway, indicating SCFAs might also induce inflammatory response. SCFAs-activated microglia promote neuronal α-synuclein aggregation and phosphorylation through activation of TLR 2, TLR4 and P-JNK/P-p38. This study indicated the role of neuronal TLR 2/4 in regulation of α-synuclein aggregation and phosphorylation.