Calcitriol in acute intracerebral haemorrhage reduces mortality in vitamin D deficient mice

Abstract

Cerebrovascular disease is the 4th most common cause of death in Hong Kong. Intracerebral haemorrhage (ICH) is a type of cerebrovascular disease with high mortality and morbidity. In ICH, disrupted haemostasis and bleeding tendency are associated with higher mortality. Haematoma size and expansion were important prognostic factors in ICH. Vitamin D deficiency (VDD) is closely related to stroke. In clinical studies, VDD has been observed to be associated with worse neurological motor deficit and higher mortality. In experimental mouse model, VDD was also found to increase ICH mortality. VDD may increase mortality in multiple ways: aggravating haematoma expansion, increasing vasogenic edema, and increasing pro-inflammatory cytokine expression. The present study is the first to demonstrate that in VDD mice, acute administration of vitamin D could reduce ICH mortality. Calcitriol, a bioactive form of vitamin D, was chosen for this study due to its rapid acting property. Calcitriol was found to reduce haematoma expansion and vasogenic edema. In this study, a mouse model for ICH was adopted. VDD was induced with a special diet, while the normal (control) group was fed normal diet. ICH was induced by injecting collagenase into the cerebrum. Mortality was measured for seven days post-ICH. Haematoma volume was measured on haemoglobin assay, histological sections, and T2*-weighted magnetic resonance imaging studies. Blood brain barrier leakage was evaluated with Evans blue extravasation study. Cytokine expression was evaluated with western blotting, quantitative polymerase chain reaction, and immunofluorescence. Acute administration of vitamin D calcitriol reduced mortality in VDD mice. A single dose of calcitriol reduced haematoma expansion and blood brain barrier leakage within 24 hrs. The findings confirmed previous reports that VDD was associated with a higher mortality rate and worse motor function post-ICH. Furthermore, VDD was associated with larger haematoma and more severe blood brain barrier leakage, consistent with the observed clinical association between VDD and disrupted haemostasis. Mechanistically, VDD was found to be associated with the upregulated expression of interleukin-1β (IL-1β) cytokine. However, treatment with IL-1β antagonist did not reduce haematoma size nor reduce mortality in VDD mice. These findings further support the existence of a causal linkage between VDD and ICH outcome and the potential therapeutic approach of early screening and treatment of VDD in ICH patients. Further studies are needed to elucidate the interactions between ICH pathophysiology, vitamin D, and IL-1β. To facilitate clinical translation, it is also necessary to determine the optimal dosing regimen of vitamin D for the rapid correction of VDD.