ABSTRACT
Cerebellar ataxias (CAs) consist of a heterogeneous group of neurodegenerative diseases hallmarked by motor deficits and deterioration of the cerebellum and its associated circuitries. Neuroinflammatory responses are present in CA brain, but how neuroinflammation may contribute to CA pathogenesis remain unresolved. Here, we investigate whether transforming growth factor (TGF)-ß1, which possesses anti-inflammatory and neuroprotective properties, can ameliorate the microglia-mediated neuroinflammation and thereby alleviate neurodegeneration in CA. In the current study, we administered TGF-ß1 via the intracerebroventricle (ICV) in CA model rats, by intraperitoneal injection of 3-acetylpyridine (3-AP), to reveal the neuroprotective role of TGF-ß1. The TGF-ß1 administration after 3-AP injection ameliorated motor impairments and reduced the calbindin-positive neuron loss and apoptosis in the brain stem and cerebellum. Meanwhile, 3-AP induced microglial activation and inflammatory responses in vivo, which were determined by morphological alteration and an increase in expression of CD11b, enhancement of percentage of CD40 + and CD86 + microglial cells, upregulation of pro-inflammatory mediators, tumor necrosis factor (TNF)-α and interleukin (IL)-1ß, and a downregulation of neurotrophic factor, insulin-like growth factor (IGF)-1 in the brain stem and cerebellum. TGF-ß1 treatment significantly prevented all the changes caused by 3-AP. In addition, in vitro experiments, TGF-ß1 directly attenuated 3-AP-induced microglial activation and inflammatory responses in primary cultures. Purkinje cell exposure to supernatants of primary microglia that had been treated with TGF-ß1 reduced neuronal loss and apoptosis induced by 3-AP-treated microglial supernatants. Furthermore, the protective effect was similar to those treated with TNF-α-neutralizing antibody. These findings suggest that TGF-ß1 protects against neurodegeneration in 3-AP-induced CA rats via inhibiting microglial activation and at least partly TNF-α release.
ABSTRACT
A simple, enzyme-free supersandwich-type biosensor is fabricated for the ultrasensitive detection of microRNAs (miRNAs) using N-doped graphene/Au nanoparticles (NG-AuNPs) and hemin/G-quadruplexes. In the proposed strategy, AuNPs are deposited on the surface of a MoSe2 modified electrode to immobilize the thiol-modified hairpin probe through the strong Au-S bond. When the target miRNA is added, capture DNA hybridizes with it and unfolds its stem-and-loop structure. The NG-AuNP hybrids are the main amplification element and are modified by hybridization with assistance DNA and the terminus of capture DNA, resulting in the formation of the supersandwich structure. The assistance DNA is embedded into the hemin/G-quadruplex complexes in the presence of hemin and K+ to provide an exceptional current signal for the detection of miRNAs. Under the optimized experimental conditions, a detection limit of 0.17 fM is obtained with a linear range of 10 fM-1 nM. In addition, the present biosensor shows outstanding selectivity towards mismatched miRNAs. This biosensor platform successfully realized the combination of the signal amplification technique with the supersandwich structure, providing a promising approach for the detection of miRNA-21 in practical applications.
