Project description:Subarachnoid hemorrhage due to rupture of intracranial aneurysm (IA) still has poor prognosis once after the onset in spite of modern technical advancement in medical care. The development of the novel therapeutic strategy based on molecular machineries regulating the rupture is thus mandatory for social health. Here, recent studies have clarified the potential role of neutrophil-mediated inflammatory responses in the process leading to rupture. Thereby, factors mediating the recruitment of neutrophils in situ could be the therapeutic targets to prevent rupture of IAs. In the present study, complement C5a receptor 1 (C5AR1) was picked up as the candidates from comprehensive gene expression profile data. The induction of C5AR1 in IA lesions exclusively in rupture-prone or ruptured lesions was then confirmed in immunohistochemistry. The ligand of C5AR1, C5a, was induced through the enzymatic digestion by tissue-type Plasminogen Activator and, intriguingly, forms the auto-amplification in C5a-C5AR1 axis to exacerbate neutrophil infiltration and resultant neutrophil-mediated inflammation in situ, which triggers rupture of IAs. In conclusion, we have, in the present study, examined potential factors mediating the infiltration of neutrophils into IA lesions and then identified C5a-C5AR1 axis. This cascade could become the therapeutic target to prevent rupture of IAs.
Project description:The biological mechanisms by which cerebral aneurysms emerge, enlarge and rupture are not totally understood. In the present study, we analyzed the genome-wide gene expression profile in human intracranial aneurysms using cDNA microarrays.
Project description:The biological mechanisms by which cerebral aneurysms emerge, enlarge and rupture are not totally understood. In the present study, we analyzed the genome-wide gene expression profile in human intracranial aneurysms using cDNA microarrays. Intracranial arterial aneurysm samples (n = 3) and normal superficial temporal artery samples (control, n = 3) were obtained from individual subjects. All aneurysm samples were unruptured aneurysms confirmed by Magnetic Resonance Image or Digital Subtraction Angiography. Affymetrix HU133 Plus 2.0 microarrays were used to compare gene expression levels between aneurismal and normal blood vessels.
Project description:To investigate the role of smoking in the rupture of intracranial aneurysms (IA), plasma miRNA profiles of smoking IA patients, non-smoking IA patients, and healthy volunteers were analyzed.
Project description:Background and Purpose—Analyzing genes involved in development and rupture of intracranial aneurysms can enhance knowledge about the pathogenesis of aneurysms, and identify new treatment strategies. We compared gene expression between ruptured and unruptured aneurysms and control intracranial arteries. Methods—We determined expression levels with RNA sequencing. Applying a multivariate negative binomial model, we identified genes that were differentially expressed between 44 aneurysms and 16 control arteries, and between 22 ruptured and 21 unruptured aneurysms. The differential expression of 8 relevant and highly significant genes was validated using digital polymerase chain reaction. Pathway analysis was used to identify enriched pathways. We also analyzed genes with an extreme pattern of differential expression: only expressed in 1 condition without any expression in the other. Results—We found 229 differentially expressed genes in aneurysms versus controls and 1489 in ruptured versus unruptured aneurysms. The differential expression of all 8 genes selected for digital polymerase chain reaction validation was confirmed. Extracellular matrix pathways were enriched in aneurysms versus controls, whereas pathways involved in immune response and the lysosome pathway were enriched in ruptured versus unruptured aneurysms. Immunoglobulin genes were expressed in aneurysms, but showed no expression in controls. Conclusions—For rupture of intracranial aneurysms, we identified the lysosome pathway as a new pathway and found further evidence for the role of the immune response. Our results also point toward a role for immunoglobulins in the pathogenesis of aneurysms. Immune-modifying drugs are, therefore, interesting candidate treatment strategies in the prevention of aneurysm development and rupture.
Project description:In the present study we aimed to investigate the systemic response to a rupture of intracranial aneurysms by an analysis of global gene expression profiles in peripheral blood cells. In addition, we sought to determine whether this approach could provide biomarkers related to clinical status of subarachnoid hemorrhage patients.
Project description:The complement system is part of the innate immune system that works to clear pathogens and cellular debris. In the central nervous system (CNS) complement activation can promote synaptic pruning clearance of neuronal blebs recruitment of phagocytes and protection from pathogens. However in a neuropathologic environment complement activation may contribute to inflammatory pathways neuronal dysfunction and in the Alzheimer’s disease (AD) brain cognitive decline. If complement activation proceeds to the cleavage of C5 and thus generation of C5a engagement of C5a with the receptor C5aR1 can instigate a feed-forward loop of inflammation injury and neuronal death thus making this molecule a potential target for modulation in AD therapeutics. The Arctic (Arc) AD mouse model known to rapidly accumulate fibrillar amyloid plaques was crossed to a model that lacks the receptor for C5a (ArcC5aR1KO) or to a transgenic mouse that generates C5a under the GFAP promoter (ArcC5a+). ArcticC5a+ mice showed accelerated loss of spatial memory compared to Arc mice. While eliminating C5aR1 did not alter amyloid plaque accumulation in this AD model C5aR1KO delayed or prevented the expression of important AD-associated genes in the hippocampus indicating a separation between those genes induced by amyloid plaques and those influenced by C5a-C5aR1 signaling. C5ar1 deletion also reduced/delayed the expression of select pan-reactive and A1 reactive astrocyte genes. ArcC5aR1KO showed delayed expression of genes enriched for biological processes that are significant in the AD context such as regulation of inflammatory signaling microglial cell activation astrocyte migration and lysosome pathway. Interestingly overexpression of C5a also delayed the increase of some AD- complement and astrocyte-associated genes perhaps mediated by C5aR2 and emphasizing the importance of selectively suppressing C5aR1. Immunohistochemical investigation further confirmed that modulation of C5a-C5aR1 either delayed or reduced some reactive microglial markers in the Arc hippocampus including CD11b and CD11c. These results suggest that C5a-C5aR1 signaling in the context of AD largely exerts its effects by suppressing those microglial activation pathways that accelerate disease enhancing pathways. Given the highly focused modulation of a common driver of neurotoxicity pharmacological inhibition of this C5aR1 signaling pathway is a promising therapeutic strategy to treat AD.
Project description:Gene expression information is useful in prioritizing candidate genes in linkage intervals. The data can also identify pathways involved in the pathophysiology of disease. We used microarrays to identify which genes are expressed in either intracranial arteries (control) or in intracranial aneurysms (case), and can therefore contribute to the disease phenotypes. We used microarrays to identify the pathway membership of expressed genes and the overrepresentation of pathways with expressed genes in the known linkage intervals for intracranial aneurysms. Keywords: Characterization of expression in both diseased and non-diseased intracranial arteries.
Project description:In the present study we aimed to investigate the systemic response to a rupture of intracranial aneurysms by an analysis of global gene expression profiles in peripheral blood cells. In addition, we sought to determine whether this approach could provide biomarkers related to clinical status of subarachnoid hemorrhage patients. Patients with subarachnoid hemorrhage from ruptured aneurysm were prospectively recruited from patients consecutively admitted to the Departments of Neurology or Neurosurgery and Neurotraumatology, University Hospital, Krakow, Poland in 2010 and 2011. Control subjects were recruited from patients of the Department of Neurology suffered from headaches.
Project description:Recent studies have indicated the involvement of neutrophil-mediated inflammatory responses in the process leading to intracranial aneurysm (IA) rupture. Receptors mediating neutrophil recruitment could thus be therapeutic targets of unruptured IAs. In this study, complement C5a receptor 1 (C5AR1) was picked up as a candidate that may cause neutrophil-dependent inflammation in IA lesions from comprehensive gene expression profile data acquired from rat and human samples. The induction of C5AR1 in IA lesions was confirmed by immunohistochemistry; the up-regulations of C5AR1/C5ar1 stemmed from infiltrated neutrophils, which physiologically express C5AR1/C5ar1, and adventitial fibroblasts that induce C5AR1/C5ar1 in human/rat IA lesions. In in vitro experiments using NIH/3T3, a mouse fibroblast-like cell line, induction of C5ar1 was demonstrated by starvation or pharmacological inhibition of mTOR signaling by Torin1. Immunohistochemistry and an experiment in a cell-free system using recombinant C5 protein and recombinant Plasmin indicated that the ligand of C5AR1, C5a, could be produced through the enzymatic digestion by Plasmin in IA lesions. In conclusion, we have identified a potential contribution of the C5a-C5AR1 axis to neutrophil infiltration as well as inflammatory responses in inflammatory cells and fibroblasts of IA lesions. This cascade may become a therapeutic target to prevent the rupture of IAs.