O'Dea Mary Isabel, Kelly Lynne, McKenna Ellen, Melo Ashanty M, Ni Bhroin Megan, Hurley Tim, Byrne Angela T, Colleran Gabrielle, Vavasseur Claudine, El-Khuffash Afif, Miletin Jan, Murphy John, Hickey Fionnuala, Molloy Eleanor J
Department of Paediatrics and Neonatology, Coombe Women & Infants University Hospital, Dublin, Ireland.
Trinity Translational Medicine Institute, Trinity College Dublin, Dublin, Ireland.
Front Pediatr. 2021 Feb 15;8:598724. doi: 10.3389/fped.2020.598724. eCollection 2020.
Neonatal encephalopathy (NE) is a significant cause of morbidity and mortality. Persistent inflammation and activation of leukocytes mediate brain injury in NE. The standard of care for NE, therapeutic hypothermia (TH), does not improve outcomes in nearly half of moderate to severe cases, resulting in the need for new adjuvant therapies, and immunomodulation holds promise. Our objective was to explore systemic leukocyte phenotype in infants with NE and healthy controls in response to lipopolysaccharide (LPS). Twenty-four infants with NE (NE II-20; NE III = 4) requiring TH and 17 term neonatal controls were enrolled, and blood samples were analyzed between days 1 and 4 of life at a mean (SD) timepoint of 2.1 (± 0.81) days of postnatal life at the time of the routine phlebotomy. Leukocyte cell surface expression levels of Toll-like receptor 4, NADPH oxidase (NOX2), CD11b, mitochondrial mass, and mitochondrial superoxide production were measured by flow cytometry. Gene expression of TRIF (TIR domain-containing adapter-inducing interferon-β), MyD88 and IRAK4 was measured by reverse transcription-polymerase chain reaction. Infants with NE had significantly lower expression of neutrophil CD11b and NOX2 with LPS stimulation compared to healthy term controls. Mitochondrial mass in neutrophils and monocytes was significantly increased in NE infants with LPS compared to controls, potentially indicating a dysregulated metabolism. Infants with NE had significantly lower IRAK4 at baseline than controls. NE infants display a dysregulated inflammatory response compared to healthy infants, with LPS hyporesponsiveness to CD11b and NOX2 and decreased IRAK4 gene expression. This dysregulated immune profile may indicate an adaptable response to limit hyperinflammation.
新生儿脑病（NE）是发病和死亡的重要原因。持续性炎症和白细胞激活介导了NE中的脑损伤。NE的标准治疗方法——治疗性低温（TH），在近一半的中重度病例中并不能改善预后，因此需要新的辅助治疗方法，免疫调节疗法有望成为新的治疗手段。我们的目的是探究患有NE的婴儿和健康对照者在接触脂多糖（LPS）后全身白细胞的表型。招募了24名需要接受TH治疗的NE婴儿（NE II级20例；NE III级4例）和17名足月儿作为对照，在出生后第1至4天、平均（标准差）为出生后2.1（±0.81）天的常规静脉采血时采集血样。通过流式细胞术检测Toll样受体4、NADPH氧化酶（NOX2）、CD11b、线粒体质量和线粒体超氧化物生成的白细胞细胞表面表达水平。通过逆转录聚合酶链反应检测TRIF（含TIR结构域的接头诱导干扰素-β）、MyD88和IRAK4的基因表达。与健康足月儿对照相比，LPS刺激后NE婴儿中性粒细胞CD11b和NOX2的表达显著降低。与对照组相比，LPS刺激后NE婴儿中性粒细胞和单核细胞的线粒体质量显著增加，这可能表明代谢失调。NE婴儿基线时的IRAK4水平显著低于对照组。与健康婴儿相比，NE婴儿表现出炎症反应失调，对LPS刺激的CD11b和NOX2反应低下，且IRAK4基因表达降低。这种失调的免疫特征可能表明是一种适应性反应，以限制过度炎症。
