Cytokine profiles in sepsis have limited relevance for stratifying patients in the emergency department: a prospective observational study

Abstract

Introduction: Morbidity, mortality and social cost of sepsis are high. Previous studies have suggested that individual cytokines levels could be used as sepsis markers. Therefore, we assessed whether the multiplex technology could identify useful cytokine profiles in Emergency Department (ED) patients.

Methods: ED patients were included in a single tertiary-care center prospective study. Eligible patients were >18 years and met at least one of the following criteria: fever, suspected systemic infection, ≥ 2 systemic inflammatory response syndrome (SIRS) criteria, hypotension or shock. Multiplex cytokine measurements were performed on serum samples collected at inclusion. Associations between cytokine levels and sepsis were assessed using univariate and multivariate logistic regressions, principal component analysis (PCA) and agglomerative hierarchical clustering (AHC).

Results: Among the 126 patients (71 men, 55 women; median age: 54 years [19-96 years]) included, 102 had SIRS (81%), 55 (44%) had severe sepsis and 10 (8%) had septic shock. Univariate analysis revealed weak associations between cytokine levels and sepsis. Multivariate analysis revealed independent association between sIL-2R (p = 0.01) and severe sepsis, as well as between sIL-2R (p = 0.04), IL-1β (p = 0.046), IL-8 (p = 0.02) and septic shock. However, neither PCA nor AHC distinguished profiles characteristic of sepsis.

Conclusions: Previous non-multiparametric studies might have reached inappropriate conclusions. Indeed, well-defined clinical conditions do not translate into particular cytokine profiles. Additional and larger trials are now required to validate the limited interest of expensive multiplex cytokine profiling for staging septic patients.

Conflict of interest statement

Competing Interests: BR & PH have received consulting fees from ThermoFisher Brahms. This does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials. VL, LA, CP, YF, GJ, PG-D, MB, ML and GG have no conflict of interest.

Figures

Figure 1. Principal component analysis and clustering of cytokine profiles in patients with (n = 102) and without (n = 24) SIRS.

Patients with (red dots) and without (blue dots) SIRS are represented according to the first three components computed using principal component analysis of either all 22 cytokines (panel A), or a more limited profile using only IL1-RA, IL-6, IL-8, IL-12, IL-13 and MCP-1 (panel B). Hierarchical cluster analysis using all 22 cytokines measured (panel C) and the limited profile (panel D) are also presented. The dendrogram at the bottom of panels C & D shows the clustering of patients with (red lines) and without (blues lines) SIRS, according to the cytokine profile selected (dendrodram at the left). The color map at the center indicates the cytokine levels for each patient (brightest green is lowest level and brightest red is higher level measured). Altogether, these analyses show that SIRS patients cannot be distinguished from non-SIRS patients.

Figure 2. Principal component analysis and clustering of cytokine profiles in patients with (n = 55) and without (n = 71) severe sepsis.

Patients with (red dots) and without (blue dots) severe sepsis are represented according to the first three components computed using principal component analysis of either all 22 cytokines (panel A), or of a limited profile using only IL-13, IL-2, sIL-2R, IL-6, IL-8, MIP-1α (panel B). Hierarchical cluster analysis using all 22 cytokines measured (panel C) and the more limited profile (panel D) are also presented. The dendrogram at the bottom of panels C & D shows the clustering of patients with (red lines) and without (blues lines) severe sepsis, according to the cytokine profile selected (dendrodram at the left). The color map at the center indicates the cytokine levels for each patient (brightest green is lowest level and brightest red is highest level measured). Altogether, these analyses show patients with severe sepsis cannot be distinguished from those without.

Figure 3. Principal component analysis and clustering of cytokine profiles in patients with (n = 10) and without (n = 116) septic shock.

Patients with (red dots) and without (blue dots) septic shock are represented according to the first three components computed using principal component analysis of either all 22 cytokines (panel A), or using only IFNγ, sIL-2R, IL-1β, IL-12, IL-17, IL-8 and TNFα (panel B). Hierarchical cluster analysis using all 22 cytokines measured (panel C) and more limited profiles only based on IFNγ, sIL-2R, IL-1β, IL-12, IL-17, IL-8 and TNFα (panel D) or sIL-2R, IL-1β, and IL-8 (panel E) are also presented. The dendrogram at the bottom of panels C, D & E shows the clustering of patients with (red lines) and without (blues lines) septic shock, according to the cytokine profile selected (dendrodram at the left). The color map at the center indicates the cytokine levels for each patient (brightest green is lowest level and brightest red is highest level measured). Altogether, these analyses show patients with septic shock cannot be distinguished from those without.

Figure 4. Principal component analysis and clustering of cytokine profiles in febrile patients with (n = 59) and without (n = 30) bacterial infection.

Febrile patients with (red dots) and without (blue dots) bacterial infection are represented according to the first three components computed using principal component analysis of either all 22 cytokines (panel A), or a more limited profile using only GM-CSF, IL-13, IL-4, IL-5, IL-6, sIL-2R, IL-17, IL-8 and TNF-α (panel B). Hierarchical cluster analysis using all 22 cytokines measured (panel C) and the more limited profile (panel D) are also presented. The dendrogram at the bottom of panels C & D shows the clustering of febrile patients with (red lines) and without (blues lines) bacterial infection, according to the cytokine profile selected (dendrodram at the left). The color map at the center indicates the cytokine levels for each patient (brightest green is lowest level and brightest red is highest level measured). Altogether, these analyses show that febrile patients with bacterial infection cannot be distinguished from those without.

Figure 5. Principal component analysis and clustering of cytokine profiles in patients with (n = 75) and without (n = 51) bacterial infection.

Patients with (red dots) and without (blue dots) bacterial infection are represented according to the first three components computed using principal component analysis of either all 22 cytokines (panel A), or a more limited profile using only IL-6, IL-8, IL-17 and GM-CSF (panel B). Hierarchical cluster analysis using all 22 cytokines measured (panel C) and the more limited profile (panel D) are also presented. The dendrogram at the bottom of panels C & D shows the clustering of patients with (red lines) and without (blues lines) bacterial infection, according to the cytokine profile selected (dendrodram at the left). The color map at the center indicates the cytokine levels for each patient (brightest green is lowest level and brightest red is highest level measured). Altogether, these analyses show that patients with bacterial infection cannot be distinguished from those without.

Figure 6. Principal component analysis and clustering of cytokine profiles in patients with proven bacterial infection (n = 31) and without (n = 51) any bacterial infection.

Patients with proven bacterial infection (red dots) and without bacterial infection (blue dots) are represented according to the first three components computed using principal component analysis of either all 22 cytokines (panel A), or a more limited profile using only TNF-α, IL-2, IL-6, IL-8, IL-17 and MCP-1 (panel B). Hierarchical cluster analysis using all 22 cytokines measured (panel C) and the more limited profile (panel D) are also presented. The dendrogram at the bottom of panels C & D shows the clustering of patients with proven bacterial infection (red lines) and without bacterial infection (blue lines), according to the cytokine profile selected (dendrodram at the left). The color map at the center indicates the cytokine levels for each patient (brightest green is lowest level and brightest red is highest level measured). Altogether, these analyses show that patients with proven bacterial infection cannot be distinguished from those without bacterial infection.