Traumatic MicroRNAs: Deconvolving the Signal After Severe Traumatic Brain Injury.

History of traumatic brain injury (TBI) represents a significant risk factor for development of dementia and neurodegenerative disorders in later life. While histopathological sequelae and neurological diagnostics of TBI are well defined, the molecular events linking the post-TBI signaling and neurodegenerative cascades remain unknown. It is not only due to the brain's inaccessibility to direct molecular analysis but also due to the lack of well-defined and highly informative peripheral biomarkers. MicroRNAs (miRNAs) in blood are promising candidates to address this gap. Using integrative bioinformatics pipeline including miRNA:target identification, pathway enrichment, and protein-protein interactions analysis we identified set of genes, interacting proteins, and pathways that are connected to previously reported peripheral miRNAs, deregulated following severe traumatic brain injury (sTBI) in humans. This meta-analysis revealed a spectrum of genes closely related to critical biological processes, such as neuroregeneration including axon guidance and neurite outgrowth, neurotransmission, inflammation, proliferation, apoptosis, cell adhesion, and response to DNA damage. More importantly, we have identified molecular pathways associated with neurodegenerative conditions, including Alzheimer's and Parkinson's diseases, based on purely peripheral markers. The pathway signature after acute sTBI is similar to the one observed in chronic neurodegenerative conditions, which implicates a link between the post-sTBI signaling and neurodegeneration. Identified key hub interacting proteins represent a group of novel candidates for potential therapeutic targets or biomarkers.

Peripheral microRNA alteration and pathway signaling after mild traumatic brain injury.

Discovering novel diagnostic biomarkers and signatures for traumatic brain injury (TBI) represents a major challenge in the brain trauma research. Detailed analysis of post-concussive molecular pathways based on experimental data could provide a new insight into the pathophysiological sequelae and mapping of recovery mechanisms involved in TBI. MicroRNAs (miRNAs) detectable in peripheral body fluids after TBI are promising carriers of this missing knowledge. In order to define the signature of peripheral miRNAs signaling associated with mild TBI (mTBI), we performed a comprehensive meta-analysis of miRNA profiles in mTBI patients using multiple curated pathway databases. Using a bioinformatic pipeline with integrated data analysis we identified a set of genes that are connected to deregulated circulating miRNAs following the mTBI. Identified genes belong to specific pathways of MAPK, TGF-ß, WNT, TLR2/4, PI3K/AKT, insulin, and growth factor signaling. Since the enriched pathways markedly overlap among the various biological fluids, signaling associated with mTBI that is concomitantly reflected in serum, plasma and saliva is robust and unique. Furthermore, we identified a network of 33 validated interacting proteins and their regulatory miRNAs that link the post-mTBI signaling in peripheral fluids with neurodegeneration-associated interaction pathways. Presented data provide a comprehensive insight into molecular events following mTBI, and the top predicted genes represent a group of novel candidate targets to be validated in connection with mTBI.

Transcriptomic signature of Alzheimer's disease tau seed-induced pathology.

Spreading of tau pathology to anatomical distinct regions in Alzheimer's disease (AD) is associated with progression of the disease. Studies in recent decade have strived to understand the processes involved in this characteristic spread. We recently showed that AD-derived insoluble tau seeds are able to initiate neurofibrillary pathology in transgenic rodent model of tauopathy. In the present study, we pursued to identify the molecular changes that govern the induction and propagation of tau pathology on the transcriptomic level. We first show that microglia in vicinity to AD-Tau-induced pathology has phagocytic morphology when compared to PBS-injected group. On transcriptomic level, we observed deregulation of 15 genes 3-month post AD-Tau seeds inoculation. Integrated bioinformatic analysis identified 31 significantly enriched pathways. Amongst these, the inflammatory signalling pathway mediated by cytokine and chemokine networks, along with, toll-like receptor and JAK-STAT signalling were the most dominant. Furthermore, the enriched signalling also involved the regulation of autophagy, mitophagy and endoplasmic reticulum stress pathways. To our best of knowledge, the study is the first to investigate the transcriptomic profile of AD-Tau seed-induced pathology in hippocampus of transgenic model of tauopathy.