Comprehensive analysis of serum concentration of matrix metalloproteinase 1 and tissue inhibitor of metalloproteinase 1 in preschool children suffering from recurrent respiratory infections

Purpose - to systematically examine the state of interrelatedness between the serum concentration of matrix metalloproteinase 1 and the tissue inhibitor of metalloproteinase 1, the frequency of acute respiratory infections (ARIs), and a heterogeneous set of other clinical and laboratory parameters in preschool children. Materials and methods. Forty children (21 boy and 33 girls) aged 1 to 6 years old, undergoing inpatient treatment on acute respiratory infection, were involved in the clinical study. They were studied serum concentrations of MMP-1 and TIMP-1, C-reactive protein, certain blood leukocyte fractions, erythrocyte sedimentation rate, the content of several macro- and microbiological elements in their hair as well as a number of clinical signs. Also, two integral indicators of ARIs recurrence were calculated, namely, the infectious index (InI) and resistance index, as well as integral indices of inflammation and dolichostenomelia. The statistical processing of the primary digital material obtained was performed by IBM SPSS Statistics 27 licensed program. Results. The younger children had higher serum MMP-1 concentrations (p=0.007) and MMP-1/TIMP-1 ratio (p=0.008) compared to the older children. The girls showed higher values of MMP-1 (p=0.008) and MMP-1/TIMP-1 ratio (p=0.012) than the boys. The strong positive correlation between MMP-1 and InI in the children (ρ=0.514; p=0.001; 95% CI [0.232; 0.716]) was demonstrated. Using ordinal logistic regression method, a significant and simultaneously multidirectional dependence of InI categorical index on MMP-1 (B=1.078; p=0.013; 95% CI [0.223; 1.933]) and the age category of the examined children (B=-1.942; 95% CI [-3.757; -0.126]) was established. Conclusions. It is assumed that more frequent ARIs in children are accompanied by higher levels of serum MMP-1. It is not unlikely that there is differential «tuning» of MMP-1 activity in response to varying frequency of ARIs during the previous year. The degree of influence of the predictor, namely MMP-1, in ordinal regression models is determined by both the significance of this predictor and the variant of its combination with other studied covariates. The study was conducted in accordance with the principles of the Declaration of Helsinki. The study protocol was approved by the local ethics committees of the institutions mentioned in the paper. An informed parental consent was obtained for the study in children. No conflict of interests was declared by the authors.