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Gene expression profiling of intracranial aneurysms

ABSTRACT: The rupture of intracranial aneurysm (IA) causes subarachnoid hemorrhage associated with high morbidity and mortality. We compared gene expression profiles in aneurysmal domes between unruptured IAs (UIAs) and ruptured IAs (RIAs) to elucidate biological mechanisms predisposing to the rupture of IA. We determined gene expression levels of eight RIAs, five UIAs, and 10 superficial temporal arteries (STAs) with the Agilent microarrays. To explore biological heterogeneity of IAs, we classified the samples into subgroups showing similar gene expression patterns by using clustering methods. The clustering analysis identified four groups: STAs and UIAs were aggregated their own clusters, whereas RIAs segregated into two distinct subgroups (early and late RIAs). By comparing gene expression levels between early RIAs and UIAs, we identified 430 up-regulated and 617 down-regulated genes in early RIAs. The up-regulated genes were associated with inflammatory and immune responses and phagocytosis including S100/calgranulin genes (S100A8, S100A9, and S100A12). The down-regulated genes suggest mechanical weakness of aneurysm walls. The expressions of Krüppel-like family of transcription factors (KLF2, KLF12, and KLF15), which were anti-inflammatory regulators, and CDKN2A, which was located on chromosome 9p21 that was the most consistently replicated locus in genome-wide association studies of IA, were also down-regulated. We demonstrate that gene expression patterns of RIAs were different according to age of the patients. The results suggest that macrophage-mediated inflammation is a key biological pathway for IA rupture. The identified genes can be good candidates for molecular markers of rupture-prone IAs and therapeutic targets.

ORGANISM(S): Homo sapiens

PROVIDER: GSE54083 | GEO | 2014/07/14

SECONDARY ACCESSION(S): PRJNA234765

REPOSITORIES: GEO

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Project description:Inorganic arsenic, a major environmental contaminant, has risen as an important health problem worldwide. More detailed identification of the molecular mechanisms associated with iAs exposure would help to establish better strategies for prevention and treatment. Although chronic iAs exposures have been previously studied there is little to no information regarding the early events of exposure to iAs. To better characterize the early mechanisms of iAs exposure we conducted gene expression studies using sublethal doses of iAs at two different time-points. The major transcripts differentially regulated at 2 hrs of iAs exposure included antioxidants, detoxificants and chaperones. Moreover, after 12 hrs of exposure many of the down-regulated genes were associated with DNA replication and S phase cell cycle progression. Interestingly, the most affected biological pathway by both 2 or 12 hrs of iAs exposure were the Nrf2-Keap1 pathway, represented by the highly up-regulated HMOX1 transcript, which is transcriptionally regulated by the transcription factor Nrf2. Additional Nrf2 targets included SQSTM1 and ABCB6, which were not previously associated with acute iAs exposure. Signalling pathways such as interferon, B cell receptor and AhR route were also responsive to acute iAs exposure. Since HMOX1 expression increased early (20 min) and was responsive to low iAs concentrations (0.1 M-oM-^AM--M), this gene could be a suitable early biomarker for iAs exposure. In addition, the novel Nrf2 targets SQSTM1 and ABCB6 could play an important and previously unrecognized role in cellular protection against iAs We used human lymphoblastoid cell line (CL-1), immortalized with Epstein-Barr virus. Cell cultures were propagated in RPMI media supplemented with 10% fetal bovine serum (FBS), L-glutammine 2 mM and antiobiotics penicillin and 10 mg/ml streptomycin) at 37M-BM-:C in an atmosphere of 5% CO2. In the case of primary cultures, 1% phytohemaglutinine were added. Cell cultures (1x106) were treated with 5M-BM-5M sodium arsenite for 2 and 12 hrs while control cultures were incubated with PBS. Nine biological replicates for each condition were used for microarray analysis. After iAs treatment, total RNA from each biological replicate was isolated with Trizol. From the 9 biological replicates performed on each condition, we generated 3 pools at a concentration of 300 ng/M-BM-5L, where each pool was processed to a single microarray platform.

Project description:<p>Our long-term objective is to identify susceptibility genes that are related to the formation of intracranial aneurysms (IA). Rupture of IAs occurs in 16,000 to 17,000 persons in the U.S. annually and nearly half of affected persons are dead within the first 30 days. An additional 6,000 to 7,000 persons with unruptured IAs are identified each year. Accumulated evidence indicates that a genetic component plays an important role in the development of IAs, but specific loci affecting the risk of IA have not been identified. The primary hypothesis of this study is that there are specific human chromosomal regions that are associated with an increased risk of IAs. Specific Aims of are: <ol> <li>Recruitment of 400 (475) families with multiple individuals who have an IA through 23 (25) referral centers throughout North America, Australia, and New Zealand that represent 35 (40) recruitment sites.</li> <li>Ascertainment of interviews and blood samples from all affected family members as well as their first-degree relatives. White blood cells from living persons with an IA will be cryopreserved at Coriell Institute for Medical Research for future immortalization of cells lines as indicated.</li> <li>Identification of unruptured IAs by obtaining MRAs in selected asymptomatic siblings (of affected individuals).</li> <li>Completion of a 10 cM genome series in persons with IAs as well as the spouses and children of persons with an IA who are deceased. We will perform finer mapping of chromosomal regions with suggestive evidence of linkage in the genome screen.</li> <li>Performance of a nonparametric (allele sharing) linkage analysis, including relevant environmental factors such as smoking, to identify chromosomal regions linked to IA. Reconstruction of the genotypes of deceased affected family members will be performed.</li> </ol> </p> <p>Identification of individuals who are genetically at high risk for the development of IAs would enable targeted and effective screening/prevention/treatment strategies to reduce the substantial mortality and morbidity associated with this devastating type of stroke. Only a multidisciplinary, collaborative effort to identify, accrue, and genotype FIA families will be successful in identifying sufficient high-risk families to characterize the genetic underpinnings of IA.</p>

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Gene expression profiling of intracranial aneurysms

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