Defensins in the biological fluids of children suffer from COVID-19: peculiarities of identification and interpretation

Abstract

The SARS-CoV-2 novel coronavirus caused a global pandemic and  mortality in the human population. Defensins are antimicrobial peptides that exert pro-inflammatory and anti-inflammatory activity and can inhibit viral infection by modulating of immune cells functions.

Aim - to study the content of defensins in biological fluids - blood serum, lung expirate, to establish their diagnostic and prognostic significance in relation to the course of the infectious process.

Materials and methods. 223 children of various ages were examined. The study group consisted of 124 patients (1^st group) who suffered from confirmed SARS-CoV-2 infection. The control group (2^nd group) included 99 children who were not diagnosed with COVID-19. The level of defensins in serum and pulmonary was determined in sick children. For calculations and statistical analysis, a statistical package was used using methods of descriptive statistics and clinical epidemiology. The population analysis evaluated attributive (AR) and relative risks (VR) with calculation of confidence intervals (95% CI) for VR and odds ratio (OR). Statistically significant differences are accepted when the Student's test is less than 0.05 (P<0.05).

Results. Determining the level of defensins in the serum of the study groups, no statistical differences were found. However, when studying the amount of peptides in the pulmonary expirate, it was found that in patients of 1^st group during the first week of the disease, the level of defensins was higher compared to of 2^nd group. The amount of polypeptides in the exhaled air condensate of patients with a complicated course of the disease was more than 300.0 pg/ml in children of 1^st group, especially girls, comparing with the control group: AR - 33%, VR - 1.86 (95% CI 1.19-2.88), OR - 4.0 (95% CI 2.14-7.49). AR=33%, VR = 1.86 (95% CI 1.19-2.88), OR = 4.0 (95% CI 2.14-7.49).

Conclusions. The condensate of pulmonary expirate infected with the SARS-CoV2 virus of children contains significantly more defensins. The highest concentrations are associated with the severity of respiratory organ damage (OR=4.0) and belonging to the female sex (P<0.05). Determination of the concentration of antimicrobial peptides in the pulmonary expirate in inflammatory processes of the respiratory system, in particular in COVID-19, can serve as a diagnostic marker.

The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. Informed consent of parents and children was obtained for research.

No conflict of interests was declared by the authors.