Neutrophil extracellular traps (NETs) have a dual role in the innate immune response to thermal injuries. NETs provide an early line of defence against infection. However, excessive NETosis can mediate the pathogenesis of immunothrombosis, disseminated intravascular coagulation (DIC) and multiple organ failure (MOF) in sepsis. Recent studies suggest that high interleukin-8 (IL-8) levels in intensive care unit (ICU) patients significantly contribute to excessive NET generation. This study aimed to determine whether IL-8 also mediates NET generation in patients with severe thermal injuries. IL-8 levels were measured in serum samples from thermally injured patients with ≥15% of the total body surface area (TBSA) and healthy controls (HC). Ex vivo NET generation was also investigated by treating isolated neutrophils with serum from thermal injured patients or normal serum with and without IL-8 and anti-IL-8 antibodies. IL-8 levels were significantly increased compared to HC on days 3 and 5 (p < 0.05) following thermal injury. IL-8 levels were also significantly increased at day 5 in septic versus non-septic patients (p < 0.001). IL-8 levels were also increased in patients who developed sepsis compared to HC at days 3, 5 and 7 (p < 0.001), day 10 (p < 0.05) and days 12 and 14 (p < 0.01). Serum containing either low, medium or high levels of IL-8 was shown to induce ex vivo NETosis in an IL-8-dependent manner. Furthermore, the inhibition of DNase activity in serum increased the NET-inducing activity of IL-8 in vitro by preventing NET degradation. IL-8 is a major contributor to NET formation in severe thermal injury and is increased in patients who develop sepsis. We confirmed that DNase is an important regulator of NET degradation but also a potential confounder within assays that measure serum-induced ex vivo NETosis.

Background: Cell-free DNA (cfDNA) released during tissue damage has attracted interest as a marker of patient outcomes. However, limited research has examined its predictive utility in thermally injured patients. Methods: This study measured cfDNA concentrations across days 1, 3, 7, 14, and 28 post-burn in a total cohort of 98 adult patients with total body surface area (TBSA) burns ≥ 15% and healthy controls (HC). CfDNA concentrations in survivors (n = 79) versus non-survivors (n = 16) were compared and area under the receiver operating curve (AUROC) models generated to evaluate cfDNA as a predictor of mortality. Results: Patient cfDNA levels were significantly elevated at all time points compared to HC. Positive correlations were identified between day 1 cfDNA concentrations (n = 95) and %TBSA (r = 0.413, p < 0.0005), rBAUX (r = 0.365, p = 0.0005) and SOFA (r = 0.391, p = 0.0002). On day one, cfDNA levels showed good discriminatory ability for distinguishing between survivors and non-survivors (AUROC 0.778), with an optimal cut-off value of 446.37 pg/mL exhibiting a sensitivity of 0.80 and specificity of 0.70. Predictive models built on rBAUX, SOFA, interleukin(IL)-6 and IL-10 generated AUROC values of 0.733, 0.743, 0.472, and 0.688 respectively. Conclusions: Major burns result in immediate and persistent cfDNA elevation, with concentrations on day one higher in non-survivors. Plasma cfDNA concentrations on day one post-burn showed good performance as a prognostic marker for mortality. CfDNA therefore represents a rapid objective measure that may be useful during acute burn assessments to aid mortality predictions.

Objectives Increased plasma levels of cell free DNA (cf-DNA) are observed in patients after severe thermal and traumatic injuries. The majority o |