(536) Combined Cytokine and Functional Immune Profiling of Critically Ill Patients

Introduction: Recent studies of adult sepsis patients demonostrate the existence of two phenotypes that differ in risk of mortality: a hyper-inflammatory phenotype with a high risk of mortality, and a hypo-inflammatory or non-inflamed phenotype with a relatively lower risk of mortality. We recently investigated the association of organ dysfunction with ex vivo immune profiling in ninety-six (96) critically ill adult patients. In this secondary analysis we measured cytokine biomarkers with an automated, microfluidic immunoassay device (Ella) and sought to investigate the functional immune profiles of patients in the hyper/hypo-inflammatory phenotype groups.

Methods: This is a secondary analysis of adult sepsis and critically ill not sepsis (CINS) cohorts of patients enrolled under an IRB-approved protocol. Subjects were consecutively identified adults, older than 18 years, within 48 hours of critical illness onset. Functional immune profiling of whole blood was performed with cytokines measured at 4h. Plasma samples were obtained and stored a -80℃ until batch analysis. Biomarkers and cytokines (CCL3, CCL7, CXCL9, CXCL10, FasL, IFN-gamma, IL-6, IL-8, IL-10, IL-18, Leptin, PD-L1, TNF, TNFR1, TRAIL) were measured using Ella.

Results: Of the cytokines measured, IL-8 (p=0.0003) and TNFR1 (p=0.0192) demonstrated the best correlation with 30-day mortality. Using these two biomarkers, the 96 patients were divided into hypo-inflammatory (77 patients) and hyper-inflammatory (18 patients) groups. The two groups demonstrated a significant (3-fold) difference in 30-day mortality (p=0.0046). Ex vivo LPS-stimulated TNF production by whole blood (4h) was lower in the hyper-inflammatory rather than the hypo-inflammatory group (p=0.0066). Ex vivo PMA/ionomycin-stimulated IFN- production by whole blood was not different between the inflammatory groups.

Conclusions: These data validate the use of IL-8 and TNFR1 to discern inflammatory sub-groups of patients with critical illness. They also confirm the observation that the presence of the hyper-inflammatory phenotype is often accompanied by a compensatory anti-inflammatory response syndrome (CARS). Future investigation is needed concerning therapeutic options for hyper-inflammatory critical illness.