Late Breaking Abstract - Interleukin-6 as a potential therapeutic target for the management of pleural infection

Interleukin-6 (IL-6) is a cytokine with a vital role in many aspects of the immune system. A mendelian randomization study conducted by our team found a strong signal between genetic IL-6 inhibition and reduced incidence of pleural infection. <bold>Aims</bold> to correlate clinical outcomes from pleural infection with IL-6 concentrations (both pleural and blood), and to investigate whether disease severity is related to IL-6 concentration. Patients with a pleural effusion secondary to infection were recruited to a prospective study and baseline samples stored. IL-6 levels were measured using commercial ELISA kit. 86 patients diagnosed with an effusion secondary to infection were included. Mean age was 60 years, 65% were male and mean length of stay was 16 days. 33% of effusions were classed as simple, 54% complex and 13% frank empyema. 72% (n=62) of all patients required a chest drain. Inpatient mortality was 4.7% while 1-year mortality was 14%. Mean serum IL-6 was 34.9 pg/ml while pleural IL-6 was 71913.5 pg/ml. Pleural IL-6 correlated with increased pleural fluid loculation (p<0.001), larger effusions (p=0.004), requirement for a chest drain (p<0.001), lower pleural fluid glucose (p=0.006), lower pleural fluid pH (p=0.002) and higher blood CRP (p<0.001). Pleural IL-6 correlated with more complex effusions and trended towards worse clinical outcomes in our cohort. Pleural IL-6 can be considered a potential target for therapy in pleural infection.