Project description:Abdominal aortic aneurysms (AAAs) are a prevalent and deadly human pathology with strong sexual dimorphism. Research demonstrates that sex hormones influence, but do not fully explain, male versus female AAA pathology. In addition to sex hormones, the X and Y sex chromosomes, and their unique complements of genes, may contribute to sexually dimorphic AAA pathology. Here, for the first time, we defined the effect of female (XX) versus male (XY) chromosome complement on AAA formation and rupture in phenotypically female mice using an established murine model. Abdominal aortas from female mice bearing the XY chromosome selectively expressed Y chromosome genes, while genes known to escape X-inactivation were higher in XX females. The majority of gene differences in XY females fell within inflammatory pathways. When XY females were infused with AngII, AAA incidences doubled and aneurysms ruptured. AAAs from XY females exhibited significant inflammation. Moreover, infusion of AngII to XY females augmented aortic activity of matrix metalloproteinases. Finally, testosterone exposure applied chronically, or as a single bolus at postnatal day 1, markedly worsened AAA outcomes in XY compared to XX females. These results demonstrate that an XY sex chromosome complement profoundly influences aortic gene expression profiles and promotes AAA severity.
Project description:Objective-Aortic pathologies exhibit sexual dimorphism, with aneurysms in the ascending, thoracic and abdominal aorta (AAA) exhibiting higher prevalence in males. Despite lower incidence of aortic vascular disease in women, aneurysms progress rapidly. Mechanisms for these sex differences are unclear. We defined the role of sex chromosome complement and testosterone in regional development and progression of angiotensin II (AngII)-induced vascular pathologies. Approach and Results-We used transgenic male mice expressing Sry on an autosome to create low density lipoprotein receptor (Ldlr) deficient male mice with an XY or XX sex chromosome complement. Subjects were then sham operated or orcheictomized. Transcriptional profiling on abdominal aortas from XY or XX males demonstrated1746 genes influenced by sex chromosomes, sex hormones, or an interaction. A second cohort of animals was then infused with AngII for 28 days. Diffuse aortic aneurysm pathology developed in XY AngII-infused males, while XX males developed discrete AAAs. Castration reduced all AngII-induced aortic pathologies in XY and XX males. Thoracic aortas from AngII-infused XY males, but not XX males exhibited adventitial thickening. We infused male XY and XX mice with saline or AngII and quantified mRNA abundance of key genes in thoracic versus abdominal aortas. Regional differences in mRNA abundance existed before AngII infusions, which were differentially influenced by AngII between genotypes. Prolonged AngII infusions resulted in AAA aortic wall thickening in XY males with diffuse aortic pathology, while XX males had dilated focal AAAs. Conclusions-An XY sex chromosome complement mediates diffuse aortic pathology, while an XX sex chromosome complement contributes to discrete AngII-induced AAAs.
Project description:Thoracic aortic aneurysms have a higher prevalence in male patients compared to female patients. Marfan syndrome causes a hereditary form of TAA with dilation of the aortic root. Male patients with Marfan syndrome are more likely than women to have aortic dilation and dissection and mouse models of Marfan syndrome demonstrate larger aortic roots in males compared to females even after adjustment for body size. Similar sex disparities are present in patients and models of abdominal aortic aneurysms where estrogen has been demonstrated to attenuate aneurysm formation perhaps through anti-inflammatory mechanisms. In this study we demonstrate the effects of estrogen on aortic dilation and rupture in a Marfan mouse model and we investigate if these effects operate through suppression of complement components of the immune system.
Project description:In this study we used microarrays to examine relative genes expression within the aorta of ApoE-/- infused with angiotensin II in relation to aneurysm formation. Infusion of angiotensin II induces aortic dilatation particularly of the suprarenal aorta in ApoE-/- mice. Based on studies carried out in our and other laboratories the response to angiotensin II is variable, with some mice developing large aneurysms but other animals appearing resistant to aneurysm formation with aortic diameters similar to that of saline controls. We compared RNA expression from whole aortas of 17 week old male ApoE-/- mice exposed to angiotensin II (1.44 µg/kg/min) for 4 weeks where there was clear evidence of aortic aneurysm formation (n=5) with that of mice failing to develop aneurysms (n=7) and those exposed to saline infusion (n=6). AAA was defined as diameter of suprarenal aorta greated than 1.5mm measured on photographs of aortas at necroscopy. Keywords: Disease state analysis 18 samples analysed, AAA (n=5), no AAA (n=7), saline (n=6). AAA - abdominal aortic aneurysm
Project description:Analysis of differential gene expression for rutured vs stable abdominal aortic aneurysms (AAA) and for intermediate size (≤55mm) vs large (>70mm) AAA.
Project description:Inadequate adaption to mechanical forces, including an elevated blood pressure, contributes to the development of arterial aneurysms. Recent studies have pointed to a mechano-protective role of YAP and TAZ in vascular smooth muscle cells (SMCs). Here, we created vascular SMC-specific knockouts (KOs) of YAP and TAZ using integrin-alpha8-Cre mice (i8-YT-KO). I8-YT-KO mice spontaneously developed aneurysms in the abdominal aorta within two weeks of knockout induction. Loss of YAP expression was also observed in human aortic aneurysms. I8-YT-KO mice developed vascular lesions in other arteries at later times, but the gastrointestinal tract was spared. Aneurysms were characterized by elastin disarray, SMC apoptosis, and accumulation of proteoglycans and inflammatory cells, including macrophages and neutrophils. RNA-sequencing, proteomics, and myography demonstrated decreased contractile differentiation of SMCs and impaired vascular contractility. This associated with partial loss of vascular myocardin expression, reduced blood pressure, and edema. Mediators in the cGAS-STING pathway, which sparks inflammation in response to double-stranded DNA, were increased in aortic lysates. A sizeable increase of the transcription factor Sox9, along with several direct target genes, including aggrecan (Acan), contributed to proteoglycan accumulation. This was the earliest detectable change, occurring three days after knockout induction, and before the pro-inflammatory transition. In conclusion, Itga8-Cre deletion of YAP and TAZ represents a rapid and spontaneous aneurysm model that re-capitulates features of human abdominal aortic aneurysms.
Project description:Fibulin-4 plays an essential role in elastic fiber formation, though it's exact function is unclear. Mice lacking the fibulin-4 gene develop cutis laxa with thoracic aortic aneurysms and have narrowed descending aortic diamaters, dying shortly after birth. Another model that disrupt elastic fiber formation, elastin gene knockeds, are also perinatally lethal and have narrowed descending aortas but do not develop thoracic aneurysms. We hypothesized that there may be altered gene expression to explain the altered anatomy based on aortic tissue location we observed, which may provide therapeutic target(s)
Project description:Fibulin-4 plays an essential role in elastic fiber formation, though it's exact function is unclear. Mice lacking the fibulin-4 gene develop cutis laxa with thoracic aortic aneurysms and have narrowed descending aortic diamaters, dying shortly after birth. Another model that disrupt elastic fiber formation, elastin gene knockeds, are also perinatally lethal and have narrowed descending aortas but do not develop thoracic aneurysms. We hypothesized that there may be altered gene expression to explain the altered anatomy based on aortic tissue location we observed, which may provide therapeutic target(s) Ascending and descending aortas of p0 mouse pups were dissected, pooled in groups of eight, and homogenized to isolate RNA and we used microarrays on the pooled samples to identify genes that had expression significantly changed.
Project description:Global gene expression information that can be used to identify pathways involved in the pathophysiology of disease. We used microarrays to identify which genes are expressed in either the abdominal aorta (control) or in abdominal aortic aneurysms (case), and also which genes may be differential between the two tissue states. Keywords: Characterization of expression in both diseased and non-diseased abdominal aortas.