A perturbed network in neurodegeneration

Aberrant protein aggregation in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal disease. As its pathological mechanisms are not well understood, there are no efficient therapeutics for it at present. While it is highly heterogenous both etiologically and clinically, it has a common salient hallmark, i.e., aberrant protein aggregation (APA). The upstream pathogenesis and the downstream effects of APA in ALS are sophisticated and the investigation of this pathology would be of consequence for understanding ALS. In this paper, the pathomechanism of APA in ALS and the candidate treatment strategies for it are discussed.

A neuron-immune circuit regulates neurodegeneration in the hindbrain and spinal cord of Arf1-ablated mice

Neuroimmune connections have been revealed to play a central role in neurodegenerative diseases (NDs). However, the mechanisms that link the central nervous system (CNS) and peripheral immune cells are still mostly unknown. We recently found that specific ablation of the Arf1 gene in hindbrain and spinal cord neurons promoted NDs through activating the NLRP3 inflammasome in microglia via peroxided lipids and adenosine triphosphate (ATP) releasing. Here, we demonstrate that IL-1β with elevated chemokines in the neuronal Arf1-ablated mouse hindbrain and spinal cord recruited and activated γδ T cells in meninges. The activated γδ T cells then secreted IFN-γ that entered into parenchyma to activate the microglia-A1 astrocyte-C3-neuronal C3aR neurotoxic pathway. Remarkably, the neurodegenerative phenotypes of the neuronal Arf1-ablated mice were strongly ameliorated by IFN-γ or C3 knockout. Finally, we show that the Arf1-reduction-induced neuroimmune-IFN-γ-gliosis pathway exists in human NDs, particularly in amyotrophic lateral sclerosis and multiple sclerosis. Together, our results uncover a previously unknown mechanism that links the CNS and peripheral immune cells to promote neurodegeneration.