Mutual exclusion of apoptosis and hsp70 in human vein intimal hyperplasia in vitro

Heat-shock proteins in cardiovascular disease

Heat-shock proteins (HSPs) belong to a group of highly conserved families of proteins expressed by all cells and organisms and their expression may be constitutive or inducible. They are generally considered as protective molecules against different types of stress and have numerous intracellular functions. Secretion or release of HSPs has also been described, and potential roles for extracellular HSPs reported. HSP expression is modulated by different stimuli involved in all steps of atherogenesis including oxidative stress, proteolytic aggression, or inflammation. Also, antibodies to HSPs may be used to monitor the response to different types of stress able to induce changes in HSP levels. In the present review, we will focus on the potential implication of HSPs in atherogenesis and discuss the limitations to the use of HSPs and anti-HSPs as biomarkers of atherothrombosis. HSPs could also be considered as potential therapeutic targets to reinforce vascular defenses and delay or avoid clinical complications associated with atherothrombosis.

THERMAL PRECONDITIONING PROTECTS THE HUMAN INTERNAL MAMMARY ARTERY FROM HYPOXIA/RE-OXYGENATION-INDUCED DAMAGE

1. Preconditioning has been demonstrated to ameliorate ischaemia/reperfusion injury in several cells and tissues. Therefore, in the present study we investigated whether preconditioning of human bypass grafts, internal mammary artery (IMA) and saphenous vein (SV) induces heat shock protein (Hsp) expression and reduces apoptosis in response to subsequent hypoxia/re-oxygenation damage in both vessels. 2. Internal mammary artery and SV rings, obtained from 30 patients (median age 66.5 years) undergoing coronary artery bypass grafting, were either incubated for 30 min at 42 degrees C (preconditioned) or kept in a standard incubator at 37 degrees C (not preconditioned). Six hours later, graft segments were exposed to 90 min hypoxia followed by a 30 min re-oxygenation period. Western blot, real-time quantative polymerase chain reaction analysis and apoptosis detection by the Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling method were performed. 3. Heat-preconditioned IMA showed significantly increased protein expression of Hsp72 after hypoxia/re-oxygenation treatment compared with controls (median 9.1 vs 5.0 microg/mg total protein; P = 0.048). Expression of Hsp73 was weak and Hsp60 was not detectable in the IMA. 4. In the SV, neither protein nor mRNA expression of Hsp were significantly different between preconditioned and not preconditioned veins. 5. There were significantly fewer apoptotic cells in the intima of the preconditioned compared with not preconditioned IMA (P = 0.041) after hypoxia/re-oxygenation injury, whereas in the SV apoptosis was not significantly prevented by preconditioning. 6. Mild heat preconditioning before hypoxia/re-oxygenation injury is a stimulus for Hsp72 protein expression and a reduction in apoptosis in the human IMA.

Pharmacological induction of HSP27 attenuates intimal hyperplasia in vivo

OBJECTIVES

intimal hyperplasia (IH) is a major cause of re-stenosis post-vascular intervention. Induction of heat shock proteins (HSPs), by thermal pre-conditioning, reduces IH. Our aim was to investigate the effect of the pharmacological HSP inducer herbimycin A on IH in the rat carotid balloon injury model.

MATERIALS AND METHODS

thirty male Sprague-Dawley rats were randomized into three groups. All groups underwent balloon injury to the left carotid artery. Stress proteins were induced 18 h pre-operatively by heat shock or herbimycin A. Two weeks post-operatively, animals were sacrificed and carotid intima/media area ratio (I/M ratio) calculated using computerized planimetry. Neo-intimal proliferation was assessed immunohistochemically with PCNA (proliferating cell nuclear antigen). Western blot and immunohistochemistry for arterial HSP70 and HSP27 were performed.

RESULTS

heat stress and herbimycin significantly reduced the I/M ratio (p < 0.05 vs balloon injury alone). Neo-intimal proliferation was significantly reduced in the heat stress and herbimycin groups (p < 0.05 vs balloon injury alone). Heat stress induced arterial HSP70 and HSP27. Herbimycin A increased arterial HSP27.

CONCLUSION

herbimycin A significantly attenuates IH after balloon injury. HSP27 may be the HSP involved in mediating this response. Pharmacological inducers of HSPs may have a therapeutic role to play in preventing re-stenosis post-vascular intervention.

Serum deprivation increases the expression of low density lipoprotein receptor-related protein in primary cultured rat astrocytes

The low density lipoprotein receptor (LDLR)-related protein (LRP) is a multifunctional receptor which mediates the endocytic uptake of several ligands implicated in Alzheimer's disease pathophysiology. Although LRP, as a member of the LDLR family, is likely to be regulated in response to various cellular stresses, this regulation has not been fully understood yet. In the present study we studied the regulation of LRP expression in primary cultured rat astrocytes in response to serum deprivation as a general cellular stress. A significant increase in LRP expression was detected after serum deprivation and this increase was blocked by treatment of U0126, an inhibitor of MAP kinase. This serum deprivation action was partially reversed by either serum or D-glucose supplementation, but further augmented by glutamine. This result contrasted with a finding that glutamine suppressed gadd153 protein induced by serum deprivation. Taken together, the present data suggest that serum deprivation induces dramatically LRP expression in astrocytes partly by MAPK signaling pathways and by signaling pathways apparently distinct from gadd153 induction.