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Inhibition of caspase-1-like activity by Ac-Tyr-Val-Ala-Asp-chloromethyl ketone induces long-lasting neuroprotection
M Rabuffetti1, C Sciorati, G Tarozzo
1Schering-Plough Research Institute, and Department of Biotechnology, San Raffaele Science Park, Milan, Italy.
Abstract:
Broad spectrum caspase inhibitors have been found to reduce neurodegeneration caused by cerebral ischemia. We studied whether blockade of group I caspases, mainly caspase-1, using the inhibitor Ac-YVAD.cmk reduced infarct volume and produced prolonged neuroprotection. Ac-YVAD.cmk (300 ng/rat) was injected intracerebroventricularly 10 min after permanent middle cerebral artery occlusion in the rat. Drug treatment induced a significant reduction of infarct volume not only 24 hr after ischemia (total damage, percentage of hemisphere volume: control, 41.1 +/- 2.3%; treated, 26.5 +/- 2.1%; p < 0.05) but also 6 d later (total damage: control, 30.6 +/- 2.2%; treated, 23.0 +/- 2.2%; p < 0.05). Ac-YVAD. cmk treatment resulted in a reduction not only of caspase-1 (control, 100 +/- 20.3%; treated, 3.4 +/- 10.4%; p < 0.01) but also of caspase-3 (control, 100 +/- 30.3%; treated, 13.2 +/- 9.5%; p < 0.05) activity at 24 hr and led to a parallel decrease of apoptosis as measured by nucleosome quantitation (control, 100 +/- 11.8%; treated, 47 +/- 5.9%; p < 0.05). Six days after treatment no differences in these parameters could be detected between control and treated animals. Likewise, brain levels of the proinflammatory cytokines IL-1beta and TNF-alpha were reduced at 24 hr (39.5 +/- 23.7 and 51.9 +/- 10.3% of control, respectively) but not at 6 d. Other cytokines, IL-10, MCP-1, MIP-2, and the gaseous mediator nitric oxide, were not modified by the treatment. These findings indicate that blockade of caspase-1-like activity induces a long-lasting neuroprotective effect that, in our experimental conditions, takes place in the early stages of damage progression. Finally, this effect is achieved by interfering with both apoptotic and inflammatory mechanisms.
Insights
Blockade of caspase-1-like activity with Ac-YVAD.cmk significantly reduced brain infarct volume and neurodegeneration in rats following cerebral ischemia. This neuroprotection was long-lasting, achieved by inhibiting both apoptotic and inflammatory processes.
Area of Science:
- Neuroscience
- Biochemistry
- Pharmacology
Background:
- Cerebral ischemia leads to neurodegeneration.
- Broad-spectrum caspase inhibitors show potential in reducing this damage.
- Group I caspases, particularly caspase-1, are implicated in ischemic injury.
Purpose of the Study:
- To investigate the neuroprotective effects of blocking group I caspases, specifically caspase-1, using Ac-YVAD.cmk.
- To determine if Ac-YVAD.cmk reduces infarct volume and provides prolonged neuroprotection after cerebral ischemia.
- To analyze the impact of Ac-YVAD.cmk on caspase activity, apoptosis, and cytokine levels.
Main Methods:
- Rats underwent permanent middle cerebral artery occlusion to induce ischemia.
- Ac-YVAD.cmk was administered intracerebroventricularly 10 minutes post-occlusion.
- Infarct volume, caspase-1 and caspase-3 activity, apoptosis (nucleosome quantitation), and cytokine levels (IL-1beta, TNF-alpha) were measured at 24 hours and 6 days post-treatment.
Main Results:
- Ac-YVAD.cmk significantly reduced infarct volume at both 24 hours and 6 days post-ischemia.
- Treatment decreased caspase-1 and caspase-3 activity and apoptosis by 24 hours.
- Pro-inflammatory cytokines IL-1beta and TNF-alpha were reduced at 24 hours but not at 6 days.
Conclusions:
- Blockade of caspase-1-like activity confers long-lasting neuroprotection in cerebral ischemia.
- The neuroprotective effect is mediated by the inhibition of early apoptotic and inflammatory mechanisms.
- Ac-YVAD.cmk demonstrates therapeutic potential for acute ischemic stroke treatment.