Ex vivo synthesized cytokines as a biomarker of stroke-associated pneumonia

Objectives: We aimed to determine a profile of ex vivo released cytokines in patients with stroke-associated pneumonia (SAP) and to assess the clinical utility of individual cytokines and their combination as a biomarker of SAP. Methods: We included 279 ischemic stroke patients (median age: 69 years; 41.6% women). We collected blood samples at day 3 after the onset of stroke and stimulated them ex vivo with lipopolysaccharide (LPS). We measured the LPS-induced cytokine concentrations (TNF alpha, IP-10, IL-1 beta, IL-6, IL-8, IL-10 and IL-12p70) as well as a plasma IL-6 level as a marker of systemic inflammation. We assessed the discriminatory ability of cytokines by calculating the area under the receiver operating characteristic curve (AUC). Results: During first 5 days after stroke pneumonia occurred in 7.2% of patients. Patients with SAP had lower ex vivo release of TNF alpha, IL-1 beta, IL-12, IP-10 and a higher level of circulating IL-6 than patients without SAP. The multimarker score composed of ex vivo synthesized IL-12, IP-10, and plasma IL-6 had better discriminatory properties than individual cytokines (AUC: 0.90). Conclusions: Our results suggest the potential utility of ex vivo synthesized cytokines as a biomarker of SAP.