Expression of the interleukin-6 gene as a predictor of severe urosepsis in patients with inflammatory kidney diseases

The objective was to evaluate the expression of the interleukin-6 (IL‑6) gene as a predictor of severe urosepsis and to justify its inclusion in the diagnostic algorithm.

Materials and methods. A prospective clinical study was conducted. The study included 90 patients: 30 patients with complicated inflammatory kidney diseases complicated by urosepsis and/or septic shock (group 1), 30 patients with uncomplicated postoperative course after surgical treatment of nephrolithiasis without signs of sepsis (group 2), and 30 practically healthy volunteers (control group). At 4 stages of observation (hospitalization/before surgery, 1st, 3rd, and 7th days), clinical and laboratory parameters, severity of organ dysfunction according to the SOFA scale (Sequential Organ Failure Assessment), traditional markers of inflammation (leukocytosis, leukocyte intoxication index – LII, C-reactive protein – CRP, procalcitonin – PCT), and expression of the IL-6 gene (IL-6) were evaluated. Statistical analysis included nonparametric criteria, correlation and ROC analysis.

Results. In patients with urosepsis, the expression of the IL 6 gene at the time of admission was significantly higher than in the control group and in patients with uncomplicated postoperative inflammation (2.06 [1.58; 2.89] vs. 0.049 [0.03; 0.09] and 0.43 [0.25; 0.55] relative units; p < 0.001). The peak of IL 6 expression occurred at the time of hospitalization and preceded the maximum increase in leukocytes, LII, CRP, and PCT, which reached their highest values on the first day of intensive care. At this stage, IL 6 expression was statistically significantly correlated with the severity of organ dysfunction according to the SOFA score (R = 0.394; p = 0.031) and the integrated inflammation index. ROC analysis showed the greatest prognostic value of IL 6 expression for detecting severe urosepsis (AUC 0.767; 95% CI 0.569–0.965; p = 0.028), while the AUC for PCT was 0.741 (95% CI 0.553–0.930; p = 0.046), for LII – 0.682, for SOFA – 0.651; total leukocytosis and CRP had low independent predictive ability (AUC 0.560 and 0.511, respectively).

Conclusion. The expression of the IL 6 gene is an early and highly sensitive molecular genetic marker of the systemic inflammatory response in patients with inflammatory kidney diseases complicated by urosepsis and/or septic shock, which is more dynamic than traditional laboratory indicators. The inclusion of the determination of IL 6 expression in the diagnostic algorithm will improve the accuracy of early risk stratification of severe urosepsis and optimize intensive care management.

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