Relationship between oxidative protein modification and the activity of lysosomal cysteine proteinases in blood plasma and leukocytes in Alzheimer’s disease

Introduction. Revealing the relationship between the severity of oxidative stress and the activity of cathepsins in tissues (plasma and blood cells) readily available for the diagnosis of Alzheimer’s disease can be useful for understanding the pathogenesis of the disease, early diagnosis, and monitoring the course of pathology. The aim of the study: identification of correlations between the level of oxidative modification of proteins and the activity of lysosomal cysteine proteinases in plasma and leukocytes in patients with Alzheimer’s disease in comparison with similar indices in patients without signs of neurodegeneration. Methods. Spectrophotometric determination of the level of carbonyl derivatives of proteins, spectrofluorometric determination of the activity of lysosomal cysteine cathepsins, analysis of correlations between indices in plasma and leukocytes (polymorphonuclear and mononuclear) both in patients with Alzheimer’s disease, and patients without signs of neurodegeneration. Results. In leukocytes in Alzheimer’s disease, a moderate negative correlation was found between the activity of cathepsin H and the level of products of oxidative protein modification. In patients with vascular dementia, a pronounced negative correlation between cathepsin B and L in polymorphonuclear leukocytes was found. A similar trend was observed in the comparison group (patients without signs of dementia and neurodegeneration). Also, in this group, a moderate positive correlation was found between the activity of cathepsin L and the level of markers of oxidative stress in blood plasma. Based on the results were made the following conclusions: • Between the activity of cathepsin H and the level of oxidative modification of proteins, a moderate negative correlation was revealed in leukocytes of patients with Alzheimer’s disease. • The activity of cathepsins B and L negatively correlates with the level of oxidative modification of proteins in polymorphonuclear leukocytes of patients with vascular dementia and cases ts without signs dementia and neurodegeneration. • The activity of cathepsin L is in direct proportion to the level of oxidative modification of the protein in the blood plasma of patients without signs of dementia and neurodegeneration.

L, H, oxidative stress, lysosomal cysteine proteases, cathepsins B, L, H, Alzheimer’s disease, neurodegeneration