The role of clotting factors VIII and IX in the development of atherosclerosis

Author(s)

Daniela Ramos Fabri

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2008-02-20

Examining board members

Joyce Maria Annichino Bizzacchi; Fernando Ferreira Costa; Wilson Nadruz Junior; Elbio D'Amico; Vania Maris Morelli

• Advisor: Valder Roberval Arruda; Joyce Maria Annichino Bizzacchi

Abstract

Complications of atherosclerosis are the most common causes of death in Western societies. The knowledge that atherosclerosis is an inflammatory disease and coagulation affects the disease's complications offers new opportunities for prevention and treatment. Population studies demonstrated that the risk for myocardial infarction is reduced by 80% among hemophilia A (HA) men compared to age and gender-matched controls. However, early atherosclerotic lesions were readily identified in small cohorts of adults HA and hemophilia B (HB) by ultrasonography of carotid and femoral arteries in a similar fashion to an agecontrol male group. Here we sought to determine the role of FVIII and FIX on the development of atherosclerosis in two different mouse models. We compared a group of FVIII (HA) or FIX deficient mice (HB) lacking the low-density lipoprotein receptor (LDLR- /-) or apolipoprotein E (APOE-/-) with hemostatically normal littermate controls lacking either LDLR (LDLR-/-) or apoE (APOE-/-). All mice were on C57Bl/6 background and all groups were matched for gender and age. Our results suggest that FVIII has a protective and time dependent effect on development of atherosclerosis in apoE deficient mice, independently of higher cholesterol levels. Notably, FVIII deficiency did not influence the vascular disease of LDLR-/- mice. Severe FIX deficiency (<1% of normal) did not protect against the development of atherosclerosis. Unexpectedly, the rates of lesions were higher at late time points in the APOE-/- model. In addition, high levels of FIX was did not influence the vascular disease in APOE-/- whereas venous thrombosis was documented in 3/6 mice. Moreover, in the HB/APOE-/- model, the rates of atherosclerosis were higher at week 22 and beyond this age these mice presented high rates of mortality than controls. These data demonstrate that FVIII and FIX play a rather heterogeneous role in the development of atherosclerosis which suggest that there are coagulation independent mechanisms in the development of vascular diseases. Further studies in hemophilia B subjects and carriers are warranted to define the FIX effect on the onset and progression of occlusive vascular disease which may raises concerns on the onset cardiovascular risks on an aging hemophilia population. (AU)