Number of blood neutrophil granulocytes is associated with diffuse coronary involvement in patients with increased lipoprotein (a)

Abstract

Aim. To assess the level of lipoprotein (a) (Lp(a)) and other lipid profile parameters, the composition of blood leukocytes in patients with focal and diffuse coronary atherosclerosis who underwent coronary artery bypass surgery (CABG), as well as to study the effect of Lp(a) on the activation of leukocytes in vitro.Material and methods. The study included 120 male patients (mean age, 67±5 years) with multivessel coronary artery disease after elective CABG surgery. According to the type of coronary artery involvement, patients were divided into groups of diffuse (n=77) and focal (n=43) atherosclerosis. In peripheral blood samples, the content of the main fractions of lipoproteins, including Lp(a), was determined. Activation of neutrophil granulocytes upon addition of Lp(a) was assessed in whole blood and in primary cell culture.Results. In patients with diffuse coronary stenosis, there was a tendency to higher Lp(a) levels; no changes in other lipid profile parameters were detected. In this group of patients, an increase in the absolute leukocyte count was noted due to neutrophilic granulocytes. An absolute neutrophil count >2,9 million/mL was associated with diffuse disease (AUC, 0,69 (95% confidence interval (CI) 0,600,77), p=0,0002, sensitivity 85%, specificity 42%). In patients with Lp(a) ³30 mg/dL, the diagnostic value of a neutrophil count >2,9 million/mL for diffuse stenosis was higher (AUC, 0,74 (95% CI 0,60-0,86), p= 0,005, sensitivity 90%, specificity 48%). According to logistic regression analysis with the introduction of neutrophils and conventional risk factors (age, body mass index, hypertension and smoking) into the model, only the number of neutrophils above the threshold level remained an independent factor in diffuse coronary stenosis. Lp(a) can induce neutrophil activation, detected by increased CD66b overexpression in whole blood, as well as the formation of neutrophil extracellular traps in primary cell culture.Conclusion. Neutrophil granulocytes can participate in the formation of diffuse atherosclerotic coronary lesions. One of the neutrophil activators may be Lp(a). The combination of high neutrophil count and Lp(a) level in the blood increases the risk of diffuse coronary atherosclerosis.

Keywords

• coronary atherosclerosis
• diffuse coronary artery disease
• lipoprotein (a)
• neutrophil granulocytes