Research article

Activation of calpain-1 in human carotid artery atherosclerotic lesions

Isabel Gonçalves^1,2 , Mihaela Nitulescu¹ , Takaomi C Saido³ , Nuno Dias⁴ , Luis M Pedro⁵ , José Fernandes e Fernandes⁵ , Mikko PS Ares¹ and Isabella Pörn-Ares^6,7

¹  Department of Clinical Sciences, Lund University, Malmö, Sweden

²  Department of Cardiology and Internal Medicine, Lund University, Malmö, Sweden

³  Laboratory for Proteolytic Neuroscience, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi Saitama 351-0198, Japan

⁴  Department of Vascular Diseases Malmö-Lund, Lund University, Malmö, Sweden

⁵  Instituto Cardiovascular de Lisboa, Lisbon, Portugal

⁶  Department of Laboratory Medicine/Experimental Pathology, Lund University, Malmö, Sweden

⁷  Research Program of Molecular Neurology, Institute of Biomedicine/Biochemistry, University of Helsinki, Helsinki, Finland

author email corresponding author email

BMC Cardiovascular Disorders 2009, 9:26doi:10.1186/1471-2261-9-26

Published:	18 June 2009

Abstract

Background

In a previous study, we observed that oxidized low-density lipoprotein-induced death of endothelial cells was calpain-1-dependent. The purpose of the present paper was to study the possible activation of calpain in human carotid plaques, and to compare calpain activity in the plaques from symptomatic patients with those obtained from patients without symptoms.

Methods

Human atherosclerotic carotid plaques (n = 29, 12 associated with symptoms) were removed by endarterectomy. Calpain activity and apoptosis were detected by performing immunohistochemical analysis and TUNEL assay on human carotid plaque sections. An antibody specific for calpain-proteolyzed α-fodrin was used on western blots.

Results

We found that calpain was activated in all the plaques and calpain activity colocalized with apoptotic cell death. Our observation of autoproteolytic cleavage of the 80 kDa subunit of calpain-1 provided further evidence for enzyme activity in the plaque samples. When calpain activity was quantified, we found that plaques from symptomatic patients displayed significantly lower calpain activity compared with asymptomatic plaques.

Conclusion

These novel results suggest that calpain-1 is commonly active in carotid artery atherosclerotic plaques, and that calpain activity is colocalized with cell death and inversely associated with symptoms.