Evolution of cytokines/chemokines in cases with community-acquired pneumonia and distinct etiologies.
Aim: To compare the systemic cytokines/chemokines levels over time during the evolution of children hospitalized with community-acquired pneumonia (CAP) with and without pneumococcal infection.
Methods: Children less than 5-years-old hospitalized with CAP were prospectively investigated in Salvador, Brazil. Clinical data and biological samples were collected to investigate 20 etiological agents and to determine serum cytokines/chemokines levels on admission and 2 to 4 weeks later. Cases with pneumococcal infection received this diagnosis irrespective of also having other etiologies.
Results: A total of 277 patients were enrolled, however, serum sample was unavailable for cytokine measurement upon admission (n = 61) or upon follow-up visit (n = 36), etiology was undetected (n = 50) and one patient did not attend the follow-up visit. Therefore, this study group comprised of 129 cases with established etiology. The median (interquartile range) age and sampling interval was 18 (9-27) months and 18 (16-21) days, respectively. Established etiology was viral (52.0%), viral-bacterial (30.2%), and bacterial (17.8%). Pneumococcal infection was found in 31 (24.0%) patients. Overall, median interleukin-6 (IL-6; 10.6 [4.7-30.6] vs 21.0 [20.2-21.7]; P = .03), IL-10 (3.5 [3.1-4.5] vs 20.1 [19.8-20.4]; P < .001), and CCL2 (19.3 [12.4-23.2] vs 94.0 [67.2-117.8]; P < .001) were significantly higher in convalescent serum samples, whereas median CXCL10 (83.6 [36.4-182.9] vs 14.6 [0-116.6]; P < .001) was lower. Acute vs convalescent levels evolution of IL-10, CCL2, and CXCL10 did not differ among patients with or without pneumococcal infection. However, IL-6 decreased (27.8 [12.3-48.6] vs 20.8 [20.2-22.6]; P = .1) in patients with pneumococcal infection and increased (9.0 [4.2-22.6] vs 21.0 [20.2-21.7]; P = .001) in patients without it.
Conclusion: The marked increase of IL-6 serum levels during the acute phase makes it a potential biomarker of pneumococcal infection among children with CAP.