Lipid peroxidation and oxidative modification of proteins in tick-borne encephalitis and ixodic tick-borne borreliosis

BACKGROUND: In the South Ural region of Russia, the group of ITTB and TBE occupies the leading rank positions in the structure of infections that are ecologically associated with ixodic ticks. At the present stage, studies aimed at studying non-specific pathological biochemical processes that determine the degree of oxidative damage to cell membranes and organelle membranes, the reactivity of the body, its reserve-adaptive potential under the influence of a number of endogenous and exogenous factors are becoming particularly relevant. One of the most significant metabolic processes of this kind is the free radical oxidation of lipids and the oxidative modification of proteins.

AIMS: To give a clinical and epidemiological characteristic and to study the role of oxidative stress in the pathogenesis of various clinical forms of tick-borne infections in an endemic region (on the example of the Chelyabinsk region).

MATERIAL AND METHODS: The study was conducted at the clinical base of the Department of Infectious Diseases of the Southern State Medical University in the MAUZ GKB No. 8 in Chelyabinsk. The study randomly included 105 patients with tick-borne encephalitis, ixodic tick-borne borreliosis and mixed infection who were hospitalized in the hospital in the period from May to October 2018–2019. The diagnosis was verified by standard immunological methods (ELISA). Modern molecular genetic methods (PCR-RV) were used in the etiological diagnosis of ICD. Material for the study: leukocyte fraction and blood serum. The content of carbonyl products of oxidative modification of proteins was estimated by their reaction with 2.4-dinitrophenylhydrazine, followed by spectrophotometric registration of the interaction products-dinitrophenylhydrazones. When determining the content of primary and secondary products of lipid peroxidation, a method based on the phenomenon of rearrangement of double bonds into diene conjugates during the peroxidation of polyunsaturated fatty acids was used. Statistical processing of the obtained results was carried out by standard methods of nonparametric statistics using the Statistica 8.0 for Windows software package.

RESULTS: In the structure of infections transmitted by ixodic ticks, ixodic tick-borne borreliosis was most often registered (50.5%), tick-borne encephalitis was observed in 44.8% of cases, mixed infection ― in 4.7%. Borrelia miyamotoi DNA was detected by PCR-RV in 8.6% of biological samples (blood serum, leukocyte fraction). When analyzing the results of oxidative modification of proteins and lipid peroxidation, a reliable picture of oxidative stress is observed, which is more pronounced in patients with ixodic tick-borne borreliosis.

CONCLUSION: The revealed changes in the study of oxidative stress in patients with tick-borne encephalitis and ixodic tick-borne borreliosis not only indicate the prospects of developing new approaches to the pathogenetic therapy of tick-borne infections, providing for the use of antioxidants in complex therapy, but also suggest a greater effectiveness of direct-acting lipophilic antioxidants that limit diene conjugation, and thereby prevent the accumulation of secondary cytotoxic products of lipid peroxidation.