Diagnostic and Prognostic Potential of Exosomal Cytokines IL-6 and IL-10 in Polytrauma Patients

Abstract

Trauma remains a leading cause of morbidity and mortality. Polytraumatized patients need a precise, early diagnosis to avoid complications such as multiorgan failure or sepsis. Inflammatory cytokines, commonly used for diagnosis, have a short half-life, which limits their efficacy as a diagnostic or prognostic marker. In this study, we hypothesized that cytokines in exosomes could have a longer half-life, and therefore could be used as diagnostic and prognostic markers in polytrauma patients. Plasma samples from polytraumatized patients (ISS ≥ 16, n = 18) were collected in the emergency room (ER) 1, 2, 3 and 5 days after trauma. Plasma-exosomes were isolated via size exclusion chromatography from polytraumatized patients and healthy volunteers (n = 10). The systemic and exosomal concentrations of interleukin (IL)-6, IL-10, IL-1β and TNF were measured using high-sensitive ELISAs. To investigate the diagnostic and prognostic potential of exosomal cytokines, data were correlated with clinical outcome parameters (injury severity, ventilation time, time in ICU and survival) documented in the patients’ electronic records. Despite the use of high-sensitive ELISAs, IL-1β and TNF alpha were not detected in exosomes. IL-6 and IL-10 were detectable in polytraumatized patient exosomes at all time points. A decrease over time of both systemic and exosomal IL-6 concentrations was observed. Furthermore, exosomal and systemic IL-6 concentrations moderately correlated (r = 0.63). Exosomal IL-6 in the ER moderately correlated with the Injury Severity Score (ISS) (mean 35.5 ± 11.5) (r = 0.45) and was associated with non-survival in polytrauma patients (p < 0.05). In contrast to IL-6, no correlation between systemic and exosomal IL-10 concentrations was found. Exosomal IL-10 concentrations remained unchanged throughout the observation time, whereas systemic IL-10 concentrations peaked in the ER and were significantly reduced after 24 h. Data from this study support our hypothesis that some cytokines (IL-10), but not all (IL-6), are detectable in exosomes significantly longer than they are in plasma. This might indicate that they are protected from degradation. Although we did not find a correlation between IL-10 exosomal concentration and patient outcome, our data confirm that exosomal cytokines are of interest as potential diagnostic and prognostic markers in polytrauma patients, and require further detailed research.

Development of a Sampling and Storage Protocol of Extracellular Vesicles (EVs)—Establishment of the First EV Biobank for Polytraumatized Patients

“…In the present study, we propose the suitability of SEC-isolated EVs for polytrauma research and showed that such EVs could be used in a differential analysis of EV surface epitopes [ 20 , 21 ] and/or a cargo analysis of cytokines [ 22 ] and miRNAs [ 23 ]. It is known that isolation methods can influence the measured total protein content of EVs [ 24 ], as well as the EV-particle number [ 25 ].…”

Identification of novel blood-based extracellular vesicles biomarker candidates with potential specificity for traumatic brain injury in polytrauma patients

“…Prior to EV isolation, plasma was additionally cleared via 30 min centrifugation at, 16000g (4°C). EVs were isolated from 100 µl of plasma by means of size exclusion chromatography (SEC) (EX03-50, Cell guidance system, Cambridge, UK) as described previously ( 18 ).…”

“…Furthermore, EVs carry biologically active surface proteins (derived from the cell of origin) that may be involved in cell-cell communication and postinjury pathology (16) and could be used for tracking injuryresponding cells. In polytrauma patients, it was shown that circulating EVs were changed in number, size, and cargo content (17)(18)(19) and that cell-specific EVs' surface proteins reflected the injury pattern (20). All the above, together with the fact that EVs can cross the blood-brain barrier (21,22), suggests that EVs might be appropriate candidates as blood biomarkers for assessing the biochemical and molecular status of neurological injury in polytrauma patients (20,23).…”

Exosome-mediated Antigen Delivery: Unveiling Novel Strategies in Viral Infection Control

“…This has been documented for interleukin-1β (IL-1β), which can be loaded and transported via exosomes in inflammatory and pyroptotic contexts [62,63]. IL-6, IL-10 and TNFalpha could also be transported in this way, giving these mediators a longer lifespan in body fluids and making again exosomes suitable markers for prognostic and diagnostic [64]. The diversity of exosomal contents also suggests a broad and still poorly understood trafficking between cellular compartments.…”