Melatonin as an immunomodulator in children with Down syndrome.

BACKGROUND: Down syndrome (DS) is a disorder characterised by marked immune dysfunction, increased mortality from sepsis, chronic inflammation, increased oxidative stress, sleep disturbance and possibly abnormal endogenous melatonin levels. Melatonin has a myriad of immune functions, and we hypothesised that this therapeutic agent could modulate the innate immune system in this cohort. METHODS: We investigated neutrophil and monocyte function (CD11b, TLR4 expression by flow cytometry), genes involved in TLR signalling (MyD88, IRAK4, TRIF), the inflammasome (NLRP3, IL-1ß), and circadian rhythm (BMAL, CLOCK, CRY) by qPCR, and inflammatory cytokines (IL-2, IL-6, IL-8, IL-18, IL-1ß, TNF-α, IFN-γ, IL-10, IL-1ra, VEGF, Epo, GM-CSF) by enzyme-linked immunosorbent assay (ELISA) following immunomodulation with LPS endotoxin and melatonin. 47 children with DS and 23 age- and sex-matched controls were recruited. RESULTS: We demonstrated that melatonin has several significant effects by reducing CD11b and TLR4 expression, attenuating TLR signalling, genes involved in the inflammasome and has the potential to reduce LPS-induced inflammatory responses. CONCLUSIONS: Immunomodulatory effects of melatonin were found in both paediatric cohorts with more marked effects in the children with DS. Melatonin mediates immune response through a wide array of mechanisms and this immunomodulator may buffer the inflammatory response by regulating pro and anti-inflammatory signalling. IMPACT: We highlight that melatonin mediates its immune response through a wide array of mechanisms, its effects appear to be dose dependant and children with Down syndrome may be more receptive to treatment with it. Immunomodulatory effects of melatonin were demonstrated with marked effects in the children with Down syndrome with a reduction of MyD88, IL-1ß and NLRP3 expression in whole-blood samples. Melatonin is a proposed anti-inflammatory agent with a well-established safety profile, that has the potential for mitigation of pro- and anti-inflammatory cytokines in paediatric Down syndrome cohorts, though further clinical trials are warranted.

Cytokine dysregulation in children with cerebral palsy.

AIM: To examine pro- and anti-inflammatory cytokines in children with cerebral palsy (CP) at baseline and in response to endotoxin (lipopolysaccharide), and correlate outcomes compared with age-matched comparisons, to evaluate their ability to mount an immune response. METHOD: Serum cytokines were assessed in 12 children (eight males, four females; mean age 10y 1mo [SD 1y 8mo], 6-16y) with CP against 12 age-matched comparisons (eight males, four females; mean age 9y 1mo [SD 1y 1mo]). Pro- and anti-inflammatory cytokines (interleukin-1ß, interleukin-2, interleukin-6, interleukin-8, interleukin-10, interleukin-18, tumour necrosis factor [TNF]-α, TNF-ß, interferon-γ, granulocyte-macrophage colony-stimulating factor [GM-CSF], vascular endothelial growth factor [VEGF], erythropoietin, and interleukin-1 receptor antagonist) were measured at baseline and in response to in vitro simulation with lipopolysaccharide by multiplex enzyme-linked immunosorbent assay. RESULTS: Significantly higher erythropoietin was found at baseline in children with CP compared with the comparison group. There was a strong response to lipopolysaccharide for interleukin-8, VEGF, TNF-α, and GM-CSF in both children with CP and the comparison group; however, there was significant lipopolysaccharide hyporesponsiveness in children with CP compared with the comparison group for interleukin-1α, interleukin-1ß, interleukin-2, and interleukin-6. INTERPRETATION: Altered cytokine responses in children with CP compared with the comparison group demonstrate an altered inflammatory state that may contribute to ongoing sequelae and could be a target for therapy. WHAT THIS PAPER ADDS: Altered inflammatory responses persist in children with cerebral palsy (CP). Erythropoietin is elevated in children with CP compared with the comparison group. Children with CP have reduced interleukin-1α, interleukin-1ß, interleukin-2, and interleukin-6 inflammatory responses to lipopolysaccharide.

Altered Cytokine Endotoxin Responses in Neonatal Encephalopathy Predict MRI Outcomes.

Background: Neonatal encephalopathy (NE) is associated with adverse neurodevelopmental outcome and is linked with systemic inflammation. Pro-inflammatory and anti-inflammatory cytokines are known to play a role in the pathology of NE by activating innate immune cells. Methods: Eighty-seven infants were enrolled including 53 infants with NE of whom 52 received therapeutic hypothermia (TH) and 34 term infant healthy controls (TC). Whole blood sampling was performed in the first 4 days of life, and a 14-spot ELISA Multiplex Cytokine Array was carried out on baseline samples or after stimulation with lipopolysaccharide (LPS) as an additional inflammatory stimulus. The cytokine medians were examined for differences between infants with NE and healthy TC; and then short-term outcomes of Sarnat stage, seizures, and MRI brain were examined within the NE group. The potential of LPS stimulation to predict abnormal MRI was explored using receiver operating characteristic (ROC) curves. Results: At baseline, infants with NE had significantly higher levels of erythropoietin (Epo), interleukin (IL)-6, and IL-1ra and significantly lower vascular endothelial growth factor (VEGF) than had controls. All cytokines were increased after LPS stimulation in infants with NE with an excessive Epo and IL-1ra response than in controls. Infants with NE had lower IL-8, IL-2, IL-6, tumor necrosis factor (TNF)-α, granulocyte-macrophage colony-stimulating factor (GM-CSF), VEGF, and interferon (IFN)-γ than controls had following LPS. GM-CSF and IFN-γ, IL-1ß, IL-1ra, and VEGF were higher on days 1-2 in NE infants with abnormal neuroimaging. GM-CSF, IFN-γ, and TNF-α levels with LPS stimulation were different upon stimulation between normal and abnormal neuroimaging. TNF-α is the only strong cytokine predictor both pre- and post-LPS stimulation of abnormal brain imaging. Conclusions: Altered cytokine responses are found in infants with NE vs. controls, and more significant differences are unmasked by the additional stimulus of LPS, which potentially improves the predictive power of these cytokines for the detection of abnormal MRIs. Infants with NE undergoing TH demonstrate both trained immunity and tolerance, and understanding these responses will facilitate adjunctive immunomodulatory treatments.