Combination Treatment With VELCADE and Low-Dose Tissue Plasminogen Activator Provides Potent Neuroprotection in Aged Rats After Embolic Focal Ischemia

Abstract

Background and Purpose Treatment with a selective proteasome inhibitor, VELCADE, in combination with tissue plasminogen activator (tPA) extended the therapeutic window to 6 hours in young rats after stroke. However, stroke is a major cause of death and disability in the elderly. The present study investigated the effect of VELCADE in combination with a low-dose tPA on aged rats after embolic stroke. Methods Male Wistar rats at the age of 18 to 20 months were treated with VELCADE (0.2 mg/kg) alone, a low-dose tPA (5 mg/kg) alone, combination of VELCADE and tPA, or saline 2 hours after embolic middle cerebral artery occlusion. To test the contribution of endothelial nitric oxide synthase to VELCADE-mediated neuroprotection, endothelial nitric oxide synthase knockout and wild-type mice were treated with VELCADE (0.5 mg/kg) 2 hours after embolic stroke. Results Treatment with VELCADE significantly reduced infarct volume, whereas tPA alone did not reduce infarct volume and aggravated blood–brain barrier disruption in aged rats compared with saline-treated rats. However, the combination treatment significantly enhanced the reduction of infarct volume, which was associated with an increase in endothelial nitric oxide synthase activity compared with saline-treated rats. Additionally, the combination treatment promoted thrombolysis and did not increase the incidence of hemorrhage transformation. VELCADE significantly reduced lesion volume in wild-type mice but failed to significantly reduce lesion volume in endothelial nitric oxide synthase knockout mice. Conclusions Treatment with VELCADE exerts a neuroprotective effect in aged rats after stroke. The combination of VELCADE with the low-dose tPA further amplifies the neuroprotective effect. Endothelial nitric oxide synthase at least partly contributes to VELCADE-mediated neuroprotection after stroke.

The thromboprotective effect of bortezomib is dependent on the transcription factor Kruppel-like factor 2 (KLF2)

“…23,24 Given that KLF2 is known to confer potent anti-inflammatory effects and induce eNOS, it is possible that these observations are secondary to increased KLF2 levels, as suggested by our studies.…”

Role of the ubiquitin–proteasome system in brain ischemia: Friend or foe?

“…Furthermore, when combined with tissue plasminogen activator (tPA), MLN519 reduced the infarct volume and improved the neurological outcome as determined 1 week after stroke . Similarly, the proteasome inhibitor bortezomib combined with low doses of tPA showed additional neuroprotective effects when tested in a model of embolic stroke in rats (Zhang et al, 2006b(Zhang et al, , 2010. Single administration of bortezomib within 2-4 h after injury also showed neuroprotective effects, and the proteasome inhibitor was proposed to act by promoting eNOSdependent vascular protection and to prevent NF-kB-dependent vascular disruption (Zhang et al, 2006b(Zhang et al, ,c, 2010.…”

Glucocorticoid Insensitivity at the Hypoxic Blood–Brain Barrier Can Be Reversed by Inhibition of the Proteasome

“…10,11 In contrast to our present results, other studies have reported beneficial effects of certain proteasome inhibitors when given as monotherapy during brain ischemia/reperfusion injury. 38,39 The exact reasons for this discrepancy are unclear at present. Differences in stroke models (eg, embolic stroke versus filament occlusion of the middle cerebral artery) and animal species (rat versus mouse) as well as divergent proteasome inhibitor formulations might play a role here.…”