Role of Interleukin-17 And Interleukin-35 In the Pathophysiology of Respiratory Infections Caused by Multidrug-Resistant Pseudomonas Aeruginosa

Abstract

Aims: The objective of this study was to assess the IL-17 and IL-35 mediated immune response of patients with respiratory infections attributable to highly resistant (MDR) Pseudomonas aeruginosa and to determine the possible role of these interleukins as biomarkers for severity of disease and clinical outcomes.

Methods and Materials: This cross-sectional study was carried out on 58 patients infected with infection with MDR P. aeruginosa respiratory tract infections in Al-Hussein Teaching Hospital, Karbala, Iraq, from August/2024 to February/2025. Abstract Background Clinical data including the severity of the disease ICU admission need for mechanical ventilation Corticosteroids use and outcomes after 3 weeks were recorded. Inflammatory markers (CRP, procalcitonin, blood cell counts), as well as serum levels of IL-17 and IL-35 were evaluated with ELISA.

Results: The results showed that IL-17 was significantly increased in patients with higher degrees of disease severity, from 56.6±9.3pg/mL in mild disease to 72.4±13.2pg/mL in severe disease (p=0.005). Moreover, higher IL-17 was significantly associated with ICU admission, mechanical ventilation requirement and poor outcomes, including mortality (75.2±13.7pg/mL). In contrast, IL-35 levels were inversely associated with disease severity, falling from 52.3±9.2pg/mL in mild disease to 42.5±7.9pg/mL in severe disease (p=0.008). Low IL-35 levels were found in patients who died (41.2±7.7pg/mL) and high IL-35 levels were found in patients with better outcome. Oxygen saturation and lymphocyte counts also presented with significantly negative correlations with IL-17, whilst IL-35 had significantly positive correlations with oxygen saturation.

Conclusion: The contrasting behaviors of IL-17 and IL-35 suggest a dynamic interplay between pro-inflammatory and anti-inflammatory responses in MDR P. aeruginosa infections. Elevated IL-17 is a marker of increased inflammation and disease severity, while IL-35 may exert protective, regulatory effects. The combined measurement of these cytokines offers promising diagnostic and prognostic value and may inform personalized management strategies for critically ill patients with MDR infections. Further research is recommended to explore their potential as therapeutic targets.

Keywords:

IL-17, IL-35, respiratory infections, MDR Pseudomonas aeruginosa

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