The activity of cathepsin D in saliva of cystic fibrosis patients.

Abstract

Cystic fibrosis (CF) is genetically determined illness, which is caused by the mutation in the CFTR gene. CFTR protein is also expressed in epithelial cells of parotid glands, therefore parotid glands are also affected in CF patients. Cathepsin D is one of the proteolitic cascade enzymes. Physiological wearing out result in occurrence of trace quantities of this enzyme in serum and body fluids, including saliva. Among different enzymes, saliva contains cathepsin D (CTSD, EC 3.4.23.5). The aim of this study was to determine cathepsin D activity in mixed saliva in cystic fibrosis patients and healthy controls. The study was performed in a group of 26 CF patients (10F, 16M). The results obtained in CF group was compared with the results of thirty healthy subjects (12F, 14M). From each subject 8 ml of mixed saliva was obtained: before and after the stimulation of saliva excretion using paraffin pledgets. Protein and glycoprotein content was assessed using Winzler's method. Protein concentration in controls and CF group before stimulation of excretion was 1.15+/-0.714 mg/mL and 1.54+/-0.925 mg/mL. After stimulation protein concentration in saliva has lowered to 0.88+/-0.77 mg/mL in CF group and 1.24+/-1.213 mg/mL in controls. Glycoprotein concentration in controls and in CF group was respectively: before stimulation 1.08+/-0.271 mg/mL and 1.05+/-0.344 mg/mL; after stimulation 0.92+/-0.292 mg/mL and 0.86+/-0.283 mg/mL. The activity of CTSD in controls was 45.9+/-24.98 Tyr nmol/mL/4h before stimulation and 109.3+/-56.94 Tyr nmol/mL/4h after stimulation of excretion. In CF group CTSD activity before stimulation was 134.5+/-81.80 Tyr nmol/mL/4h and after stimulation 134.4+/-62.18 Tyr nmol/mL/4h. Comparing the CTSD activity in both groups statistically significant difference has been revealed in samples collected before stimulation of excretion (p=0.013). The activity of cathepsin D in saliva of cystic fibrosis patient is significantly higher than in healthy controls before the stimulation of excretion with paraffin pledgets.