Abstract Introduction: Systemic Inflammation is associated with Traumatic Brain Injury (TBI) and therefore is a potential target for immunomodulation. Dysregulated immune function post-TBI increased susceptibility to infection and post-concussive syndrome. The inflammasome is a protein complex associated with an amplified proinflammatory response and is a potential target for immunomodulation that preserves antimicrobial immunity. Methods: Samples from children with mild TBI (mTBI; Glasgow coma scale (GCS) 14/15), severe TBI (sTBI; GCS < 8) and control children were collected at baseline and two week follow up and were treated with endotoxin and melatonin. Toll-like receptor (TLR4; marker of endotoxin responses) and CD11b (activation marker) expression on neutrophils and monocytes were evaluated by flow cytometry. Inflammasome-related genes and cytokines were assessed using TaqMan RT-PCR samples ELISA sandwich immunoassay, respectively. Results: A total of 214 children were enrolled including: TBI (n = 116), with mild TBI (mTBI; Glasgow coma scale (GCS) 14/15) and severe TBI (sTBI; GCS < 8), and (n = 98) control patients collected at baseline and two week follow up. Total monocyte and intermediate monocyte populations were reduced in mTBI at baseline. Neutrophil CD11b and TLR4 expression was decreased in mTBI at 10–14 days. NLRP3 and NLRP1 were downregulated at 10–14 days while IL-1β was increased at baseline at 0–4 days and further elevated by 10–14 days and significantly higher in those with no previous mTBI. Serum cytokines showed lower IL-18 and raised IL-33 in those with mTBI. Prior concussion did not influence serum cytokine levels. In addition, LPS did not stimulate an IL-18 and IL-1β response in the mTBI group at 10–14 days. Conclusions: Children with mTBI had reduced CD11b and TLR4 expression and NLRP3 inflammasome activation. IL-1β mRNA was raised and continued to rise after injury implicating the innate immune system in the subacute phase of injury. Immune dysregulation post-TBI in children may be a target for immunomodulation following further exploration in vitro of potential mechanisms and therapies.

The immune system is inexperienced before birth and tends to be tolerogenic, rather than immunogenic. After birth, the adaptive immune system develops while facing microbial challenges, but it can become impaired as old age progresses and persistent inflammation can lead to chronic morbidity, disability and frailty. To investigate the potential contributions of lymphocyte subsets to immunity from birth until old age, we enumerated circulating innate and conventional lymphocytes and measured serum cytokine levels in 10 cord blood samples and in peripheral blood from 10 healthy term neonates, 23 healthy school-age children, 25 young adults and 11 older subjects. Flow cytometric analysis revealed that B cell frequencies increase during childhood and gradually decrease into adulthood, whereas natural killer cell frequencies increase throughout life. T cell frequencies remained relatively constant throughout life, as did their expression of CD4 and CD8. However, all four innate T cell populations studied—invariant natural killer T cells, mucosa-associated invariant T cells and the Vδ1 and the Vδ2 subsets of γδ T cells—were extremely rare in cord blood and in peripheral blood of neonates, but they expanded after birth reaching highest levels in adulthood. Analysis of serum cytokine levels revealed that proinflammatory and T helper type 1 (Th1) cytokine levels increase in adulthood, whereas Th2 and Th17 cytokine levels remain relatively constant. These changes in lymphocyte numbers and cytokine levels across the lifetime are likely to affect immunocompetence, leaving newborn and elderly people susceptible to infection, cancer and immune-mediated disease.

MIS-C is a systemic inflammation disorder with poorly characterised immunopathological mechanisms. We compared changes in the systemic immune response in children with MIS-C (n = 12, 5–13 years) to healthy controls (n = 14, 5–15 years). Analysis was done in whole blood treated with LPS. Expression of CD11b and Toll-like receptor-4 (TLR4) in neutrophils and monocytes were analysed by flow cytometry. Serum cytokines (IL-1β, IL-2, IL-6, IL-8, IL-10, IL-Ira, TNF-α, TNF-β, IFN-Υ, VEGF, EPO and GM-CSF) and mRNA levels of inflammasome molecules (NLRP3, ASC and IL-1β) were evaluated. Subpopulations of lymphocytes (CD3 + , CD19 + , CD56 + , CD4 + , CD8 + , TCR Vδ1 + , TCR Vδ2 + ) were assessed at basal levels. Absolute counts of neutrophils and NLR were high in children with MIS-C while absolute counts of lymphocytes were low. Children with MIS-C had increased levels of IL-6, IL-10, TNF-β and VEGF serum cytokines at the basal level, and significantly increased TNF-β post-LPS, compared to controls. IL-1RA and EPO decreased at baseline and post-LPS in MIS-C patients compared to controls. The percentage of CD3 + cells, NK cells and Vδ1 was lower while B cells were higher in children with MIS-C than in controls. Dysregulated immune response in children with MIS-C was evident and may be amenable to immunomodulation.

of these risk factors has led to substantial reduction (80%) in the rate of SIDS over last 2 decades, it is still the leading cause of death in infants between four weeks and 6 months of age. The most recent data provided by Irish central statistics office reports 14 deaths (0.21 deaths per 1000 live births) in year 2014. We aimed to find out the awareness of the risk factors leading to SIDS amongst mothers who delivered at Mullingar Regional Hospital. Methods A prospective assessment was performed by distributing multidimensional questionnaire to the women admitted in postnatal ward following birth of their baby in Mullingar Regional Hospital, Ireland. Anonymously collected data was analysed using SPSS2 software. Regional hospital ethical committee approved the study. Results One hundred two participants were included in analysis. 9.6 percent (n=9) participants had never heard of SIDS. Of those who had, 46% (43/93) and 54% (53/93) have heard it from healthcare providers and media respectively. Major risk factors identified by number of participants were; prone sleeping position (80%, 75/93), overheating of the baby (91%, 85/93), Soft bedding (90%, 84/93), bed sharing of infants (69%, 65/93), Maternal smoking during pregnancy (60%, 56/93), Smoking around babies environment (58%, 54/93) and maternal alcohol intake during pregnancy (56%, 53/93). 20% participants failed to identify prone sleeping position as the risk factor. A significant number of participants were unaware of other major risk factors such as smoking during pregnancy, smoking around baby and bed sharing with baby.100% of the participants wanted more information about SIDS. Televised campaign (68%, 70/102) and reading materials (56%, 58/102) were the 2 most preferred method of delivering SIDS information to the participants. 66% (68/102) participants wanted the information delivered as part of prenatal education and further 29% (30/ 102) wanted it before discharge from the post-natal ward. 53.9% (55/102) and 31% (32/102) participants opted midwife/maternity nurses and paediatrician respectively as the person to deliver information about SIDS. Conclusions This study concludes that there is a wide gap in knowledge about risk factors for SIDS and almost all participants felt they need more information. We hope implementing methods to narrow this knowledge gap would further reduce the incidence of SIDS.

OBJECTIVES:Glial fibrillary acidic protein (GFAP) is a neuronal protein released after traumatic brain injury (TBI) and detectable in serum samples. GFAP correlates with symptom severity in adults and may be a marker of brain injury in children with milder symptoms or preverbal children. METHODS:GFAP was examined in children with severe TBI (initial Glasgow Coma Scale score <8), with mild TBI (Glasgow Coma Scale score 14/15), and at 0 to 4 and at 10 to 14 days after TBI and was compared with healthy age-matched controls. Mechanism, time points from injury, and symptoms were recorded. RESULTS:The study enrolled 208 children including 110 with TBI (n = 104 mild, 6 severe) and controls (n = 98). GFAP was higher in mild TBI than in controls and highest in the severe TBI cohort, with a maximum value at 6 hours from injury. Vomiting was significantly associated with higher GFAP levels, but no association was found with amnesia, loss of consciousness, and the Sports Concussion Assessment Tool. Children reporting >1-point changes from their preinjury functioning on the Post-Concussive Symptom Inventory had higher initial GFAP but not total Post-Concussive Symptom Inventory score changes. CONCLUSIONS:GFAP identifies children with TBI, even at the milder end of the spectrum, and is strongly associated with postinjury vomiting. It may be a useful marker of pediatric TBI; however, sampling is time critical.

ObjectivesGlial fibrillary acidic protein (GFAP) is a neuronal protein released after traumatic brain injury (TBI) and detectable in serum samples. GFAP correlates with symptom severity in adults and may be a marker of brain injury in children with milder symptoms or preverbal children.MethodsGFAP was examined in children with severe TBI (initial Glasgow Coma Scale score <8), with mild TBI (Glasgow Coma Scale score 14/15), and at 0 to 4 and at 10 to 14 days after TBI and was compared with healthy age-matched controls. Mechanism, time points from injury, and symptoms were recorded.ResultsThe study enrolled 208 children including 110 with TBI (n = 104 mild, 6 severe) and controls (n = 98). GFAP was higher in mild TBI than in controls and highest in the severe TBI cohort, with a maximum value at 6 hours from injury. Vomiting was significantly associated with higher GFAP levels, but no association was found with amnesia, loss of consciousness, and the Sports Concussion Assessment Tool. Children reporting >1-point changes from their preinjury functioning on the Post-Concussive Symptom Inventory had higher initial GFAP but not total Post-Concussive Symptom Inventory score changes.ConclusionsGFAP identifies children with TBI, even at the milder end of the spectrum, and is strongly associated with postinjury vomiting. It may be a useful marker of pediatric TBI; however, sampling is time critical.

We enumerated conventional and innate lymphocyte populations in neonates with neonatal encephalopathy (NE), school-age children post-NE, children with cerebral palsy and age-matched controls. Using flow cytometry, we demonstrate alterations in circulating T, B and natural killer cell numbers. Invariant natural killer T cell and Vδ2+ γδ T cell numbers and frequencies were strikingly higher in neonates with NE, children post-NE and children with cerebral palsy compared to age-matched controls, whereas mucosal-associated invariant T cells and Vδ1 T cells were depleted from children with cerebral palsy. Upon stimulation ex vivo, T cells, natural killer cells and Vδ2 T cells from neonates with NE more readily produced inflammatory cytokines than their counterparts from healthy neonates, suggesting that they were previously primed or activated. Thus, innate and conventional lymphocytes are numerically and functionally altered in neonates with NE and these changes may persist into school-age.

Children with Down syndrome (DS) develop more infections, have an increased mortality from sepsis and an increased incidence of chronic inflammatory conditions. Cytokine dysregulation may underpin these clinical sequelae and raised pro-inflammatory biomarkers are a feature in adults with DS. The importance of the anti-inflammatory mediators IL-1ra and IL-10, as well as cytokines Epo and VEGF, which could impact on the pathogenesis and outcomes in congenital heart disease (CHD) which is more prevalent in DS, are less well known. We examined a comprehensive array of pro-(IL-2, IL-6, IL-8, IL-18, IL-1β, TNF-α, IFN-γ), and anti-inflammatory (IL-10 and IL-1ra) mediators, cytokines involved in inflammation in response to hypoxia (EPO), propagating angiogenesis (VEGF), and myelopoiesis (GM-CSF), by enzyme linked immunosorbent assay (ELISA), as well as discussing the potential impact of significant CHD and Lipopolysaccharide endotoxin on these mediators. 114 children with DS and 60 age and sex matched controls were recruited. Children with Down syndrome exhibit significantly greater levels of pro and anti-inflammatory cytokines; IL-2, IL-6, IL-10, IL-1ra, as well as increased Epo, VEGF and GM-CSF at baseline. CHD does not seem to have an impact on circulating cytokines beyond the acute surgical phase. Both cohorts had similar responses to LPS stimulation. These differences may contribute to varied clinical outcomes, acutely like in sepsis, and over time in autoimmunity.

The following abstracts are those that we presented at the research competition of the Student Medical Summit held in the Talbot Hotel Stillorgan on the 15th February 2020. For more information about the Student Medical Summit visit www.studentmedicalsummit.org or contact info@studentmedicalsummit.org

ObjectiveTo establish the relationship between serum point-of-care (POC) ketones at triage and moderate-to-severe dehydration based on the validated Gorelick Scales.Design, setting and patientsProspective unblinded study from April 2016 to February 2017 in a paediatric emergency department. Patients aged 1 month to 5 years, with vomiting and/or diarrhoea and/or decreased intake with signs of moderate or severe dehydration or clinical concern for hypoglycaemia were eligible.Main outcome measuresThe primary outcome was to describe the relationship between triage POC ketones to the two Gorelick Scales. Secondary outcomes were to examine the response of ketone levels to fluid/glucose administration and patient disposition.ResultsOne-hundred and ninety-eight patients were included; median age 1.8 years. The median triage ketones were 4.6 (IQR 2.8–5.6) mmol/L. A weak correlation was identified between triage ketones and the 10-point Gorelick Scale (Spearman’s ρ=0.217, p=0.002), however no correlation between triage ketones and the 4-point Gorelick Scale was identified. Those admitted had median triage ketones of 5.2 (IQR 4–6) mmol/L and repeat ketones of 4.6 (IQR 3.3–5.7) mmol/L compared with 4.2 (IQR 2.4–5.3) mmol/L and 2.9 (IQR 1.6–4.2) mmol/L in those discharged home.ConclusionNo correlation between triage POC ketones and the 4-point Gorelick Scale was established. POC ketones at triage have poor accuracy for predicting hospital admission. The elevated profile of POC ketones in non-diabetic children with acute illness suggests a potential target of tailored treatments for further research.

Histological chorioamnionitis (HCA) is associated with preterm birth and adverse neonatal outcomes. We evaluated the rise in C-reactive protein (CRP) in preterm infants as a predictor of HCA severity and outcomes. Consecutive preterm infants, born January 2009 to January 2014 in the National Maternity Hospital, Dublin, under 32 weeks' gestation or <1.5 kg birthweight, were included. Histological chorioamnionitis was staged as maternal inflammatory response, foetal inflammatory response and non-HCA. Preterm infants (n = 518) were included with a mean gestational age 28.5 ± 2.8 weeks, birthweight 1.1 ± 0.3 kg, and 53.5% were male. Histological chorioamnionitis was found in 25.4%. Histological chorioamnionitis was present in 93.7% when CRP > 5 mg/L, 65.2% when CRP 1-5 mg/L and in 19.4% when CRP < 1 mg/L. When both the immature to total neutrophil (IT) ratio was >0.2 and the CRP > 1 mg/L the positive predictive value and negative predictive value for HCA were 92.5% and 84.9%, respectively. Histological chorioamnionitis was associated with more resuscitation and respiratory distress syndrome (both P < .001). A CRP > 10 mg/L was associated with a foetal inflammatory response and increased early-onset sepsis. Higher early CRP was a surrogate predictor of HCA and correlated with the severity of HCA. Higher CRP and HCA were associated with adverse early outcomes.

Aim Histological chorioamnionitis (HCA) is associated with preterm birth and adverse neonatal outcomes. We evaluated the rise in C-reactive protein (CRP) in preterm infants as a predictor of HCA severity and outcomes. Methods Consecutive preterm infants, born January 2009 to January 2014 in the National Maternity Hospital, Dublin, under 32 weeks' gestation or <1.5 kg birthweight, were included. Histological chorioamnionitis was staged as maternal inflammatory response, foetal inflammatory response and non-HCA. Results Preterm infants (n = 518) were included with a mean gestational age 28.5 +/- 2.8 weeks, birthweight 1.1 +/- 0.3 kg, and 53.5% were male. Histological chorioamnionitis was found in 25.4%. Histological chorioamnionitis was present in 93.7% when CRP > 5 mg/L, 65.2% when CRP 1-5 mg/L and in 19.4% when CRP < 1 mg/L. When both the immature to total neutrophil (IT) ratio was >0.2 and the CRP > 1 mg/L the positive predictive value and negative predictive value for HCA were 92.5% and 84.9%, respectively. Histological chorioamnionitis was associated with more resuscitation and respiratory distress syndrome (bothP < .001). A CRP > 10 mg/L was associated with a foetal inflammatory response and increased early-onset sepsis. Conclusion Higher early CRP was a surrogate predictor of HCA and correlated with the severity of HCA. Higher CRP and HCA were associated with adverse early outcomes.

Following burns during neonatal intubation, we mounted an in vitro study of laryngoscopes to determine the temperatures reached during clinical use. The temperature of 10 different bulb laryngoscopes heads and two fibre optic heads were measured with a thermocouple, once opened, and upon closing. Within 60 s, all ten laryngoscopes, with light-bulb sources, had gained significant heat to cause thermal injury to neonatal skin. Laryngoscopes with LED light source and fibre optic heads did not. Conclusion: We recommend that the bulb laryngoscope blade, if used, is not left open prior to intubation and that it is closed between intubation attempts.

Aims To evaluate end components of the innate immune system, the inflammsome, in mild Traumatic Brain Injury (TBI), a pathway activated in mild tramatic brain injury and to correlate with previous exposure to head injury. Methods Whole blood was sampled from children with mild TBI at presentation with injury and compared to healthy paediatric controls at baseline. RNA was isolated and cDNA was synthesized. Gene Expression of IL-1 β via rtPCR was recorded in 18 patients 5 controls at baseline. Of 18 patients, 10 had previously suffered concussion. Results Mechanisms of injury included sporting and school yard clashes, falls from bikes and falls from bed. GCS was 14 – 15/15 in all. Inflammasome was upregulated via IL-1 β expression in children with previous episodes of mTBI compared to those with no previous history. (p = 0.08) The highest IL-1 β, 8000 fold that of baseline. This was recorded in a child who had previously had rehabilitation following a road traffic accident 7 years previously. Conclusion Inflammation is altered in TBI compared to controls. IL-1 β gene transcription was higher in those with previous episodes of concussion. Immune memory may be a factor in the clinically evident burden of symptoms following repetitive head trauma, and this warrants further exploration.

Background Toll like receptors (TLRs) are key in initiating innate immune responses. TLR2 is crucial in recognising lipopeptides from gram positive bacteria and is implicated in chronic inflammation. Children with Down syndrome (DS) are prone to infections from these pathogens and have an increased risk of autoimmunity. Sparstolonin B (SsnB) is a TLR antagonist shown to reduce cytokine production and improve outcomes in sepsis. We hypothesized that TLR2 signalling may be anomalous in children with DS and contribute to their clinical phenotype. Aims We aimed to evaluate TLR2 pathways in 3 ways; by determining the expression of TLR2 on the surface of neutrophils, monocytes, and their subsets; examine gene expression of key regulatory proteins involved in TLR signal propagation, MyD88, IRAK4, and TRIF; and lastly to determine cytokine production at baseline and following immunomodulation with pro-inflammatory stimuli (LPS, Pam3Csk4) and the anti-inflammatory agent SsnB. Methods Whole blood was collected from children with DS and age matched controls. Samples were treated with lipopolysaccharide (LPS) 10ng/ml, Pam3Csk4 (5ng/ml), SsnB (10μM) or in combination. TLR2 and CD11b expression on neutrophils and monocytes was evaluated by flow cytometry. RNA was isolated from Trizol®, cDNA was synthesized and then evaluated by quantitative PCR for expression of MyD88, IRAK4, and TRIF. A panel of pro and anti-inflammatory cytokines were evaluated using the MSD®MULTI-SPOT assay system from Mesoscale (MSD Diagnostics, USA). Statistical analysis employed unpaired t-tests, ANOVA, analysed using GraphPad Prism and FloJo software. Results Children with DS (n=20) and controls (n=15) were recruited. TLR2 expression was significantly raised on neutrophils (p=0.02), total monocytes (p=0.05), intermediate monocytes (p=0.02) in children with DS compared to controls. At baseline the expression of MyD88 was significantly lower (p=0.001), and TRIF significantly raised in children with DS (p≤0.0001). The TLR antagonist SsnB was effective at reducing TLR2 and CD11b expression and abrogating cytokine production in both cohorts. Conclusion TLR2 pathway is dysregulated in DS. There is greater expression of TLR2 on the surface of neutrophils and monocytes. Downstream signalling is altered with reduced MyD88 and increased expression of TRIF, which may represent compensatory upregulation of MyD88 independent pathways. This altered innate immunity may contribute to chronic inflammation in DS. SsnB attenuates pro-inflammatory mediators and could be of therapeutic benefit.

Aims To evaluate components of the innate immune system, the inflammsome, in mild Traumatic Brain Injury (TBI) and the correlation with symptom burden 2 weeks from injury. We examine activation of the pathway at presentation, and also at 2 weeks from injury compared with healthy control children. Methods Whole blood was sampled from children with mild TBI within 24 hours of injury and at two weeks from injury and compared to healthy paediatric controls at baseline. RNA was isolated and cDNA was synthesized. Gene Expression of NLRP3 and IL1 β via rtPCR was recorded in 22 patients and 5 controls at baseline and 15 patients at 2 weeks. The Post Concussive Symptom Inventory was administered at 2 weeks. A change from pre-injury baseline was recorded. Results Inflammasome was upregulated via NLRP3 expression in children with TBI compared to controls across groups however this did not correlate with symptoms at 2 weeks. Higher IL-1β transcription levels at presentation were positively correlated by Pearson correlation (p = 0.029) with higher symptom scores at 2 weeks. Conclusion Inflammation is altered in TBI compared to controls The NLRP3 component of inflammasome while elevated does not correlate with symptom burden. IL=1 β gene transcription does. IL-1 β holds promise in predicting symptom burden following mTBI. Selective inhibition of systemic inflammation targeting the inflammasome may have a future immunomodulatory role as a target in treating mTBI.

Background Mild Traumatic Brain Injury (mTBI) is a common childhood occurrence with a more severe phenotype in adolescence. Systemic inflammation has been demonstrated to be integral to the pathogenesis of ongoing symptoms. The inflammasome is a component of innate immunity that is involved in regulating and inducing inflammation in response to cell damage and may have a modifiable role in mTBI. Objective We demonstrated inflammasome pathway activation in response to mTBI. We hypothesized that pubertal development modulates inflammasome activation. We correlated pubertal scores with inflammasome gene transcription. Methods Children were recruited to the study following presentation to the emergency department with symptomatic head injuries (GCS 14/15; n=21) and compared to age-matched Controls (n=10). Pubertal developmental self-rating scales (PDS) with 5 rating questions were administered with a maximum score of 20. mRNA was extracted from whole blood and the Inflammasome components [Interleukin (IL)- 1beta and NLR Family Pyrin Domain Containing 3 (NLRP3)] in mTBI and controls were profiled with RT-PCR analysis on the ABI 7900. Results The mean age of children recruited was 12.0(±3.9) years with 18 males. Both NLRP3 and IL-1β were significantly raised in the mTBI group versus controls (p<0.0001). IL-1β was significantly downregulated at 2 weeks post TBI (p<0.0001). There was a significant correlation between pubertal score and IL-1β in mTBI (p=0.04). Conclusion Inflammasome activation via the NLRP3 pathway is important in paediatric mTBI. IL1beta activation was more prominent in children at more advanced stages of puberty. The interplay of pubertal maturity and the innate immune system may explain the greater burden of symptoms in patients during adolescence.

Toll-like receptors (TLRs) are the key in initiating innate immune responses. TLR2 is crucial in recognising lipopeptides from gram-positive bacteria and is implicated in chronic inflammation. Children with Down syndrome (DS) are prone to infections from these pathogens and have an increased risk of autoimmunity. Sparstolonin B (SsnB) is a TLR antagonist which attenuates cytokine production and improves outcomes in sepsis. We hypothesised that TLR signalling may be abnormal in children with DS and contribute to their clinical phenotype. We evaluated TLR pathways in 3 ways: determining the expression of TLR2 on the surface of neutrophils and monocytes by flow cytometry, examining the gene expression of key regulatory proteins involved in TLR signal propagation, MyD88, IRAK4, and TRIF, by quantitative PCR, and lastly determining the cytokine production by ELISA following immunomodulation with proinflammatory stimuli (lipopolysaccharide (LPS), Pam3Csk4) and the anti-inflammatory agent SsnB. We report TLR2 expression being significantly increased on neutrophils, total monocytes, and intermediate and nonclassical monocytes in children with DS (n=20, mean age 8.8±SD 5.3 years, female n=11) compared to controls (n=15, mean age 6.2±4.2 years, female n=5). At baseline, the expression of MyD88 was significantly lower, and TRIF significantly raised in children with DS. The TLR antagonist SsnB was effective in reducing TLR2 and CD11b expression and abrogating cytokine production in both cohorts. We conclude that TLR signalling and the TLR2 pathway are dysregulated in DS, and this disparate innate immunity may contribute to chronic inflammation in DS. SsnB attenuates proinflammatory mediators and may be of therapeutic benefit.

Aims To evaluate systemic inflammation in TBI by exploration of the inflammasome pathway, a component of the innate immune system that regulates and induces inflammation. We examine the pathway at baseline in TBI compared with healthy control children, and in vitro in response to both LPS stimulation and melatonin therapy. Melatonin has protective effects against NLRP3 inflammasome activation and has therapeutic implications. Methods Whole blood was sampled from children with TBI (n=10) within 24 hours of injury and compared to healthy age-matched controls (n=8) at baseline, following stimulation with bacterial endotoxin (LPS) (10ng/ml) and melatonin treatment (10–3M). Granulocytes were delineated as CD66b+ and FSC, SSC-A. Measurements of mean channel fluorescence (MCF) of CD11b and TLR4 expression on FACS Canto II were recorded and analysed with FloJo software v10. Gene Expression of NLRP3 via rtPCR was recorded in 10 patients and 10 controls at baseline and following LPS and melatonin treatment. Results Granulocyte CD11b expression was lower in children with TBI compared to controls (p=0.04) Both upregulated CD11b with LPS stimulation. Melatonin significantly decreased this LPS upregulation. There was no significant difference in baseline TLR4 expression between TBI and controls, but LPS upregulation of TLR4 was decreased by melatonin in the TBI cohort. Inflammasome was upregulated via NLRP3 expression in children with TBI compared to controls (p= 0.02). Melatonin significantly decreased LPS-induced upregulation of NLRP3 only in controls. Conclusion Inflammation is altered in TBI compared to controls with altered responsiveness to melatonin treatment following LPS stimulation. The inflammasome is downregulated in children immediately following TBI. Selective inhibition of systemic inflammation targeting the inflammasome may have a future immunomodulatory role as a target in treating TBI.