Fasudil Decreases Lesion Burden in a Murine Model of Cerebral Cavernous Malformation Disease

Abstract

Background and Purpose Cerebral cavernous malformations (CCMs) are characterized by grossly dilated capillaries, associated with vascular leak and hemorrhage, and occur in sporadic or inherited (autosomal dominant) forms with mutations in one of three gene loci (CCM 1, 2 or 3). We previously reported that the CCM1 protein (KRIT1) localizes to endothelial cell-cell junctions and loss of KRIT1 leads to junctional instability associated with activation of RhoA and its effector Rho kinase (ROCK). Although ROCK inhibition has been proposed as potential therapy for CCM, there has been no demonstration of a therapeutic effect on CCM lesion genesis in vivo. Methods Our recently generated a model of CCM1 disease (Ccm1+/−Msh2−/−) was treated with ROCK inhibitor fasudil (100 mg/kg/day administered in drinking water from weaning to 5 months of age), or placebo, and blindly assessed CCM lesion burden by systematic survey of animals’ brains. For comparison, we also assessed therapeutic effect in previously described Ccm2+/−Trp53−/− mice, treated with the same dose and duration of fasudil and placebo. Results Fasudil treated Ccm1+/−Msh2−/− mice had a significantly decreased prevalence of CCM lesions compared to placebo controls. Lesions in treated animals were smaller and less likely associated with hemorrhage, inflammation and endothelial proliferation, and exhibited decreased expression of ROCK activation biomarkers. A therapeutic effect was also documented in Ccm2+/−Trp53−/− mice. Conclusion This represents the first report of therapeutic benefit of pharmacological therapy in development and progression of CCMs, and indicates that ROCK activation is a critical step in CCM lesion genesis and maturation.

Vascular Permeability in Cerebral Cavernous Malformations

“…The loss of endothelial cell integrity in association with inherited heterozygous germ line mutations has been shown to result in 'leaky' vasculature not just within the CCM lesions themselves, but in nonlesional vascular beds. The increased brain permeability in familial patients compared with sporadic cases shows a direct translation of experimental observations made in murine models, 3,8 and serves as a proof of concept that ROCKinduced brain vascular hyperpermeability may be quantitated in the clinical setting.…”

“…3 The ROCK activity has been linked to increased CCM lesion burden in mice, and ROCK inhibition is being tested as a potential therapy to prevent CCM lesion development. 8 A similar vascular hyperpermeability would be expected, but has never been shown, in patients with familial CCM disease, which may represent a biomarker of disease activity and response to treatment.…”

“…This hyperpermeability is rescued by ROCK inhibition, a proposed therapy for CCM disease. 3,8,10 Statin medication was shown to reverse dermal hyperpermeability associated with heterozygous Ccm in mice. 6 Until the present study, it has not been determined whether vascular permeability measurements in the human brain could reflect the differences postulated mechanistically.…”

Ccm3, a gene associated with cerebral cavernous malformations, is required for neuronal migration

“…CCM3 loss results in defects in neuronal migration and in actin and microtubule cytoskeletal remodeling, processes partly regulated by Rho GTPases (Heng et al, 2010;Govek et al, 2011;Kawauchi, 2011 Borikova et al, 2010;Stockton et al, 2010;Zheng et al, 2010;Louvi et al, 2011;McDonald et al, 2011;Cappello et al, 2012;McDonald et al, 2012). RhoA and Ccm3 have similar expression in neocortex and are required in radial glia for neuronal migration (this study) (Cappello et al, 2012).…”

Cerebral cavernous malformation proteins at a glance

“…Each of these functions can be rescued by ROCK inhibition (Borikova et al, 2010;Stockton et al, 2010;Whitehead et al, 2009). ROCK inhibitors also rescue lipopolysaccharide-induced vascular leak in KRIT1-and CCM2-deficient mice (Stockton et al, 2010) and inhibit the formation of vascular lesions in other mouse models (McDonald et al, 2012). Targeting RhoA-ROCK signaling is therefore one potential therapeutic strategy for CCM (Li and Whitehead, 2010).…”