Pravastatin acute neuroprotective effects depend on blood brain barrier integrity in experimental cerebral ischemia.

Statins have since long been reported to exert acute neuroprotection in experimental stroke models. However, crucial questions still need to be addressed as far as the timing of their cerebral effects after intravascular administration and the role played by the blood brain barrier (BBB) crossing properties. We tested the effects of an hydrophilic statin (pravastatin, 100 nM), which poorly crosses BBB under physiological conditions. Pravastatin was administered either 90 min before or immediately after transient middle cerebral artery occlusion in the in vitro isolated guinea pig brain preparation. A multi-modal outcome assessment was performed, through electrophysiological and cerebral vascular tone recordings, MAP-2 immunohistochemistry, BBB evaluation via ZO-1/FITC-albumin analysis, AKT and ERK activation and whole-cell antioxidant capacity. Pravastatin pre-ischemic administration did not produce any significant effect. Pravastatin post-ischemic administration significantly prevented MAP-2 immunoreactivity loss in ischemic areas, increased ERK phosphorylation in the ischemic hemisphere and enhanced whole-cell antioxidant capacity. Electrophysiological parameters, vascular tone and AKT signaling were unchanged. In all tested ischemic brains, ZO-1 fragmentation and FITC albumin extravasation was observed, starting 30 min from ischemia onset, indicating loss of BBB integrity. Our findings indicate that the rapid anti-ischemic effects of intravascular pravastatin are highly dependent on BBB increased permeability after stroke.

Acute lipophilicity-dependent effect of intravascular simvastatin in the early phase of focal cerebral ischemia.

The acute effects of simvastatin lactone (lipophilic) and simvastatin acid (hydrophilic) on transient focal ischemia were assessed using the isolated guinea pig brain maintained in vitro by arterial perfusion. This new model of cerebral ischemia allows the assessment of the very early phase of the ischemic process, with the functional preservation of the vascular and neuronal compartments and the blood-brain barrier (bbb). The middle cerebral artery was transiently tied for 30 min followed by reperfusion for 60 min. Statins (nanomolar doses) were administered by intravascular continuous infusion starting 60 min before ischemia induction. Brain cortical activity and arterial vascular tone were continuously recorded. At the end of the experiment immunoreactivity for microtubule-associated protein 2 (MAP-2), expression of survival kinases (ERK and Akt) and total anti-oxidant capacity were assayed. Brains treated with simvastatin lactone showed i) reduced amplitude and delayed onset of ischemic depressions, ii) preservation of MAP-2 immunoreactivity, iii) activation of ERK signaling in the ischemic hemisphere and iv) increase in whole-brain anti-oxidant capacity. Treatment with the bbb-impermeable simvastatin acid was ineffective on the above-mentioned parameters. Vascular resistance recordings and Akt signaling were unchanged by any statin treatment. Our findings suggest that intravascular-delivered simvastatin exerts an acute lipophilicity-dependent protective effect in the early phase of cerebral ischemia.

IL4 gene delivery to the CNS recruits regulatory T cells and induces clinical recovery in mouse models of multiple sclerosis.

Central nervous system (CNS) delivery of anti-inflammatory cytokines, such as interleukin 4 (IL4), holds promise as treatment for multiple sclerosis (MS). We have previously shown that short-term herpes simplex virus type 1-mediated IL4 gene therapy is able to inhibit experimental autoimmune encephalomyelitis (EAE), an animal model of MS, in mice and non-human primates. Here, we show that a single administration of an IL4-expressing helper-dependent adenoviral vector (HD-Ad) into the cerebrospinal fluid (CSF) circulation of immunocompetent mice allows persistent transduction of neuroepithelial cells and long-term (up to 5 months) CNS transgene expression without toxicity. Mice affected by chronic and relapsing EAE display clinical and neurophysiological recovery from the disease once injected with the IL4-expressing HD-Ad vector. The therapeutic effect is due to the ability of IL4 to increase, in inflamed CNS areas, chemokines (CCL1, CCL17 and CCL22) capable of recruiting regulatory T cells (CD4+CD69-CD25+Foxp3+) with suppressant functions. CSF delivery of HD-Ad vectors expressing anti-inflammatory molecules might represent a valuable therapeutic option for CNS inflammatory disorders.

Absence of an intrathecal immune reaction to a helper-dependent adenoviral vector delivered into the cerebrospinal fluid of non-human primates.

Inflammation and immune reaction, or pre-existing immunity towards commonly used viral vectors for gene therapy severely impair long-term gene expression in the central nervous system (CNS), impeding the possibility to repeat the therapeutic intervention. Here, we show that injection of a helper-dependent adenoviral (HD-Ad) vector by lumbar puncture into the cerebrospinal fluid (CSF) of non-human primates allows long-term (three months) infection of neuroepithelial cells, also in monkeys bearing a pre-existing anti-adenoviral immunity. Intrathecal injection of the HD-Ad vector was not associated with any sign of systemic or local toxicity, nor by signs of a CNS-specific immune reaction towards the HD-Ad vector. Injection of HD-Ad vectors into the CSF circulation may thus represent a valuable approach for CNS gene therapy allowing for long-term expression and re-administration.