Dynamics of T helper subpopulations in the critical period of severe injury in children

Abstract

Severe mechanical injury is one of the main reasons behind children’s disability and mortality. Severe injury induces a complex host immune response to tissue injury, a parallel pro- and anti-inflammatory state, bearing an elevated risk for infectious complications (IC) and/or multiple organ failure (MOF). This study aimed to determine the informative immunological criteria of traumatic injury severity and prognosis outcome in children (severe injury group (SInj, ISS ≥ 16), n = 87; mild/moderate injury group (MInj, ISS < 16), n = 34) based on the assessment of absolute cell count (abs) and percentage of such T helper subpopulations as regulatory T lymphocytes – CD4+CD127lowCD25high(Treg), Th17 lymphocytes – CD4+CD161+ and CD4+CD127higtCD25high T cells(T127hi) in severe injury cases grouped by the outcome (favorable, n = 47; unfavorable, n = 40) and depending on IC (n = 16) and the development of MOF (n = 11) on the 1st, 3d , 5th, 7th, 14th day after injury. The control group was comprised of 80 apparently healthy children comparable in age and sex. An inverse relationship between severity of injury, degree of blood loss and outcome of injury was revealed with the abs of all Th populations, but for Th abs and Treg abs the most significant correlation was found (Spearman’s R ≤ -0,70, p < 0.00001). For SInj group, a pronounced decrease of Th abs, Treg abs, T127hi abs and Th17 abs, in the acute post-traumatic period with an increase to 14 days was revealed. The values of in the first day for indicators of patients with MInj group correspond to the values of control group and significantly differ from SInj group. There are different kinetics of percentage Th subpopulations in peripheral blood of children with severe injuries. The Th17%CD4+ and T127hi%CD4+ significant increase in 1st-3d and 3d -7th days after injury respectively in comparation with сontrol and MInj groups. There were no differences between groups in terms of Treg%CD4+. The lower-level Treg abs in trauma patients admitted to the ICU is significantly associated with develop the infectious complications and outcome of trauma. The Th17 abs is significantly reduced in 3-7th days after the injury in the SInj group with MOF. The results of the study indicate that in children levels of Treg, T127hi and Th17 is significantly associated with severity of injury and may be used to predict outcome of trauma and assess the risk of IC and MOF.