Aortic dissection (AD) is a life threatening emergency. Early diagnosis and treatment are pivotal for patients with AD. Matrix metalloproteinases (MMPs), through degradation of extracellular matrix, may play an important role in these processes. Elevation of MMPs might represent an opportunity to diagnostically characterise acute aortic processes. We examined the potential diagnostic role of MMP-9 in AD.
Methods Between February 2009 and November 2009, 86 consecutive patients affected by acute AD who were admitted to our emergency department for evaluation were enrolled in this study (Traumatic AD, Marfan Syndrome were excluded). Blood samples were obtained from venipuncture in EDTA tubes from fasting patients at the time of hospital admission. Plasma levels of MMPs were evaluated by ELISA in 86 patients affected by AD (28 type A, 58 type B). 30 healthy subjects were used as controls. Aortic tissue samples obtained during surgery were evaluated by immunohistochemistry and western blot for MMP-9 expression. In addition, control tissue was obtained from subjects who underwent heart transplantation (2 male and 1 female). Data were analysed by SPSS statistical software (version 13.0). All data were presented as mean±SEM. A two-tailed unpaired Student t test was used to assess differences in MMP levels. p<0.05 was considered statistically significant.
Results Mean plasma values for MMP-9 were higher in patients affected by AD compared to control group at the time of hospital admission (22.78±1.28 ng/ml vs 17.45±1.36 ng/ml p<0.05). Moderate/strong expression (++/++++) of MMP-9 was present in both the intima and media layers at the entry site in AD compared to control aortas, Western blot analysis confirmed the expression of MMP-9 in AD whereas no/low (−/+) expression was present in control aortas.
Conclusions This pilot study suggests that MMPs play an important role in the pathophysiology of AD and that the acute phase of AD is characterised by an increase of MMP-9 plasma levels. In this setting, the detection of aortic dissection using biochemical techniques would represent an attractive, rapid, non-invasive and easy to perform diagnostic tool. Future investigation of MMPs and their inhibitors in AD will likely lead to advancements in the diagnosis, prognosis, and treatment of this deadly disease.