Neutrophil count and complex lesions in patients with coronary artery disease

Leukocyte and leukocyte subset counts reveal compensatory mechanisms in coronary heart disease

BACKGROUND

Leukocyte number in the circulation plays a central role in inflammatory diseases, such as coronary heart disease (CHD). Increased counts are correlated with the intensity of the peri-infarction inflammatory response and adverse outcomes. We investigated leukocyte and leukocyte subset counts in dyslipidaemia patients and their relationship with LDL oxidation.

METHODS

Dyslipidaemia patients (207) were selected for blood counts and LDL-C testing. The level of HNP-1and myeloperoxidase in subsets of leukocytes and their relationship with LDL oxidation were compared between 24 CHD patients and 24 normal controls.

RESULTS

In dyslipidaemia patients, total leukocyte and neutrophil counts increased with LDL-C (p=0.001). Monocyte counts showed the opposite trend (p=0.001). Although serum HNP-1 levels were not different between CHD patients and normal controls (p=0.558), neutrophil HNP-1 mRNA levels were 2.13-fold greater than those of normal controls. However, monocyte HNP-1 mRNA levels were lower (p=0.005). The distribution of myeloperoxidase in monocytes and neutrophils is different, myeloperoxidase locates mainly in the cytoplasm of monocytes, on the cell membrane of neutrophils.

CONCLUSIONS

Leukocyte and leukocyte subset counts may correlate with LDL-C levels and LDL oxidation. The monocyte-neutrophil interaction reveals a potential compensatory mechanism associated with LDL oxidation in CHD that may be a prognostic factor of CHD.

Human neutrophil peptides mediate endothelial-monocyte interaction, foam cell formation, and platelet activation

OBJECTIVE

Neutrophils are involved in the inflammatory responses during atherosclerosis. Human neutrophil peptides (HNPs) released from activated neutrophils exert immune modulating properties. We hypothesized that HNPs play an important role in neutrophil-mediated inflammatory cardiovascular responses in atherosclerosis.

METHODS AND RESULTS

We examined the role of HNPs in endothelial-leukocyte interaction, platelet activation, and foam cell formation in vitro and in vivo. We demonstrated that stimulation of human coronary artery endothelial cells with clinically relevant concentrations of HNPs resulted in monocyte adhesion and transmigration; induction of oxidative stress in human macrophages, which accelerates foam cell formation; and activation and aggregation of human platelets. The administration of superoxide dismutase or anti-CD36 antibody reduced foam cell formation and cholesterol efflux. Mice deficient in double genes of low-density lipoprotein receptor and low-density lipoprotein receptor-related protein (LRP), and mice deficient in a single gene of LRP8, the only LRP phenotype expressed in platelets, showed reduced leukocyte rolling and decreased platelet aggregation and thrombus formation in response to HNP stimulation.

CONCLUSIONS

HNPs exert proatherosclerotic properties that appear to be mediated through LRP8 signaling pathways, suggesting an important role for HNPs in the development of inflammatory cardiovascular diseases.

Human neutrophil peptides: a novel potential mediator of inflammatory cardiovascular diseases

The traditional view of atherosclerosis has recently been expanded from a predominantly lipid retentive disease to a coupling of inflammatory mechanisms and dyslipidemia. Studies have suggested a novel role for polymorphonuclear neutrophil (PMN)-dominant inflammation in the development of atherosclerosis. Human neutrophil peptides (HNPs), also known as alpha-defensins, are secreted and released from PMN granules upon activation and are conventionally involved in microbial killing. Current evidence suggests an important immunomodulative role for these peptides. HNP levels are markedly increased in inflammatory diseases including sepsis and acute coronary syndromes. They have been found within the intima of human atherosclerotic arteries, and their deposition in the skin correlates with the severity of coronary artery diseases. HNPs form complexes with LDL in solution and increase LDL binding to the endothelial surface. HNPs have also been shown to contribute to endothelial dysfunction, lipid metabolism disorder, and the inhibition of fibrinolysis. Given the emerging relationship between PMN-dominant inflammation and atherosclerosis, HNPs may serve as a link between them and as a biological marker and potential therapeutic target in cardiovascular diseases including coronary artery diseases and acute coronary syndromes.