Investigating the use of t-lymphocyte and cytokine biomarkers to predict clinical outcomes of major trauma patients

Edirisinghe, Nalik

Abstract

Trauma remains a leading cause of morbidity and mortality globally with a significant burden across the globe irrespective of socio-economic levels. In the UK, major trauma (MT) as a result of motor vehicle accidents is the leading cause of death in adults under the age of 40, however, more recent studies have highlighted an increase in trauma-related deaths in the elderly as a result of head injuries caused by falls. Despite advancements in therapies or widely available major trauma centres across the UK, trauma remains a major cause of death and disability and is a severe economic burden on the NHS.

The bimodal model stipulated that the majority of deaths related to MT occurs immediately (withing 24 hours) or during later stages (5 days-12 days) of injury. Early complications include haemorrhagic shock, while chronic complications include multiple organ dysfunction syndrome (MODS), acute respiratory distress syndrome (ARDS), and sepsis. The link between post-traumatic pro-and counter-inflammatory responses with MODS and ARDS is modelled by the two-hit theory. Patterns of pro-and counter-inflammatory cytokines such as interlukin-6 (IL-6) and interlukin-10 (IL-10) coupled with T-cell, particularly Treg, activity could provide a potential diagnostic insight into identifying patients with poorer prognosis and outcomes.

Data collection for this study, including the investigation of blood samples (59 patients from the Central Manchester Foundation Trust and 29 from the Salford Royal Foundation Trust prior to this study) was carried out as part of a larger study by members of the University of Salford trauma research group. Analytic methodologies for cellular CD marker definition included peripheral mononuclear cell isolation, retrieval, fluorochrome labelling and FACS verse flowcytometric analysis. IL-6 and IL-10 cytokine characterisation was carried out by cytometric bead array assays (CBA) using the BD Biosciences reagent kit and FACS Verse flow cytometry analysis.

The aim of the work presented in this dissertation is to analyse patterns of T-cell subsets in comparison to proinflammatory cytokine IL-6 and counter inflammatory cytokine IL-10, in order to assess the potential interactions between cellular and humoral inflammatory marker in evolution of inflammatory organ damage in MT. Sequential Organ Failure Assessment scores (SOFA scores at <3 or ≥3 cut offs) were calculated to assess organ damage over days 1-5 post trauma as a proxy indicator of the onset of ARDS/MODS.

One-way ANOVA was used to investigate differences between days 1, 3, and 5 for the T-cell subsets and interleukins included in this study. Significant differences were observed between days 1, 3 and 5 CD4+, CD8+, IL-6 , and IL-10 . Unpaired T-tests were used to investigate differences between T-cell subset trends in Days 1, 3 and 5 in relation Day 5 SOFA scores as a measure of outcomes. Day 3 CD3+ , CD25DIMFOXP3+, and CD2BRIFOXP3+ were significantly different when grouped based on day 5 SOFA scores. Day 5 CD3+ was also significantly different when grouped based on day 5 SOFA scores. Significant differences were also observed on day 1 when IL-10 was grouped based on day 5 SOFA scores.

Spearman’s Rank correlations test was used to investigate the correlations between interleukins and T-cell subsets. Significant correlations were observed between day 5 IL-6 and day 5 T-cell subsets as detailed below. Day 1 IL-6 was significantly correlated with Day 1 CD3+. Day 5 IL-10 was significantly correlated with day 5 CD3+, CD4+ , CD25+ , CD25DIM , CD25BRI , and CD25BRIFOXP3+ . Further analysis was performed by grouping T-cell subsets and interleukins by Day 5 SOFA scores to investigate correlations with ARDS/MODS. Within day 5 SOFA <3 group, IL-6 was significantly correlated with CD25DIM and CD25BRI and within the day 5 SOFA ≥3 groups IL-6 was significantly correlated with CD25BRI . Day 1 IL-10 was significantly correlated with day 1 CD3+ (day 5 SOFA <3 p= 0.04 and day 5 SOFA ≥3 p=0.009) on both groups. Day 5 IL-10 was significantly correlated with Day 5 CD25+ , CD25DIM, CD25BRI , CD4+FOXP3+ and CD25BRIFOXP3+ within the day 5 SOFA <3 group.

Early increase in both IL-6 and IL-10 followed by a significant reduction in both IL-6 and IL-10 by day 3 was associated with poor outcome patients as defined by SOFA score of ≥3 of Day 5 post trauma and could be a potential early predictor of sepsis and MODS. Elevation of CD3+ levels from day 1 to 3 was associated with a SOFA score of ≥3 and could be used as a potential predictor of poor clinical outcome. Similarly, an increase in CD4+ and a reciprocal reduction in CD8+ was observed in cluster of patients progressing to have SOFA scores of ≥3 on Day 5 post trauma, the change was not statistically significant.

An increased Day 3, CD25BRIFOXP3+ level was associated with poor clinical outcomes on Day 5 . In conclusion, our preliminary analysis shows that cytokine markers (IL-10 Day 1) and CD cellular markers (CD3+, CD25BRIFOXP3 Day3) could have a predictive role in the early identification of MT patients destined for poor clinical outcome post Day. Clearly, further, large cohort studies are warranted to confirm our findings.

Citation

Edirisinghe, N. Investigating the use of t-lymphocyte and cytokine biomarkers to predict clinical outcomes of major trauma patients. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Nov 7, 2024
• Award Date: Nov 21, 2024