quantitative-micro-ct-analysis-aortopathy-mouse-model

Quantitative Micro-CT Analysis of Aortopathy in a Mouse Model of &#946;-aminopropionitrile-induced Aortic Aneurysm and Dissection

Aortic aneurysm and dissection is associated with significant morbidity and mortality in the population and can be highly lethal. While animal models of ...

University of Maryland School of Medicine

Thrombus resolution is a complex process that involves thrombosis, leukocyte-mediated thrombolysis, and the final resolution of inflammation. Activated protein C (APC) is an anticoagulant that also possesses immunoregulatory activities.

Activated protein C accelerates venous thrombus resolution through heme oxygenase-1 induction.

The resolution of deep vein thrombosis requires an inflammatory response and mobilization of proteases, such as urokinase-type plasminogen activator (uPA) and matrix metalloproteinases (MMPs), to degrade the thrombus and remodel the injured vein wall. Plasminogen activator inhibitor type 2 (PAI-2) is a serine protease inhibitor (serpin) with unique immunosuppressive and cell survival properties that was originally identified as an inhibitor of uPA.

Enhanced venous thrombus resolution in plasminogen activator inhibitor type-2 deficient mice.

Deep venous thrombosis (DVT) remains a common and serious cardiovascular problem with both fatal and long-term consequences. The consequences of DVT include the development of post-thrombotic syndrome (PTS) in 25-60% of DVT patients. Despite the clinical importance of venous thrombus resolution, the cellular and molecular mediators involved are poorly understood, and currently there is no molecular therapy to accelerate this process. Several lines of evidence suggest that a complex and interrelated array of molecular signaling processes are involved in the inflammatory vascular remodeling associated with the resolution of DVT. Here, we have identified a role for the tumor suppressor gene p53 in regulating venous thrombus resolution. Using the stasis model of venous thrombosis and resolution in mice, we found that genetic deficiency of p53 or pharmacologic inhibition by pifithrin, impairs thrombus resolution and is associated with increased fibrosis and altered expression of the metalloproteinase MMP-2. The effect of p53 loss was mediated by cells of the myeloid lineage, resulting in enhanced polarization of the cytokine milieu towards an M1-like phenotype. Further, augmentation of p53 activity using the pharmacological agonist of p53, quinacrine, accelerates venous thrombus resolution in a p53 dependent manner, even after establishment of thrombosis. Together these studies define mechanisms by which p53 regulates thrombus resolution by increasing inflammatory vascular remodeling of venous thrombi in vivo, and the potential therapeutic application of a p53 agonist as a treatment to accelerate this process in patients with DVT.

Myeloid p53 regulates macrophage polarization and venous thrombus resolution by inflammatory vascular remodeling in mice.

Compromised gastrointestinal barrier function is strongly associated with the progressive and destructive pathologies of the two main forms of irritable bowel disease (IBD), ulcerative colitis (UC), and Crohn's disease (CD). Matriptase is a membrane-anchored serine protease encoded by uppression of umorigenicity- ( gene, which is critical for epithelial barrier development and homeostasis. Matriptase barrier-protective activity is linked with the glycosylphosphatidylinositol (GPI)-anchored serine protease prostasin, which is a co-factor for matriptase zymogen activation. Here we show that mRNA and protein expression of both matriptase and prostasin are rapidly down-regulated in the initiating inflammatory phases of dextran sulfate sodium (DSS)-induced experimental colitis in mice, and, significantly, the loss of these proteases precedes the appearance of clinical symptoms, suggesting their loss may contribute to disease susceptibility. We used heterozygous  hypomorphic mice expressing a promoter-linked β-gal reporter to show that inflammatory colitis suppresses the activity of the  gene promoter. Studies in colonic T84 cell monolayers revealed that barrier disruption by the colitis-associated Th2-type cytokines, IL-4 and IL-13, down-regulates matriptase as well as prostasin through phosphorylation of the transcriptional regulator STAT6 and that inhibition of STAT6 with suberoylanilide hydroxamic acid (SAHA) restores protease expression and reverses cytokine-induced barrier dysfunction. Both matriptase and prostasin are significantly down-regulated in colonic tissues from human subjects with active ulcerative colitis or Crohn's disease, implicating the loss of this barrier-protective protease pathway in the pathogenesis of irritable bowel disease.

Article	Year
Activated protein C accelerates venous thrombus resolution through heme oxygenase-1 induction. Journal of thrombosis and haemostasis : JTH\| PubMed ID: 24119206	2014
Enhanced venous thrombus resolution in plasminogen activator inhibitor type-2 deficient mice. Journal of thrombosis and haemostasis : JTH\| PubMed ID: 25041188	2014
Myeloid p53 regulates macrophage polarization and venous thrombus resolution by inflammatory vascular remodeling in mice. Blood\| PubMed ID: 28320710	2017
Inflammatory cytokines down-regulate the barrier-protective prostasin-matriptase proteolytic cascade early in experimental colitis. The Journal of biological chemistry\| PubMed ID: 28490634	2017

Subhradip Mukhopadhyay

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