ABSTRACT
BACKGROUND: Interleukin 6 (IL-6) induce the inflammatory response directly related with the morbidity and mortality of neonatal. Here we aimed to explore the mechanism of IL-6 in neonatal inflammatory response by studying the IL-6/STAT3 signaling pathway. METHODS: Cord blood samples from health term neonatal and peripheral venous blood from health volunteers were collected. The monocytes of adults and cord blood were isolated and induced into macrophages. Then the macrophages were pretreated with or without MG132 before IL-6 stimulation. Proteins were analyzed by Western blot, mRNA by real time PCR and membrane molecule by flow cytometry. RESULTS: The acute phase protein gene expression in neonatal macrophages after stimulated with IL-6 were higher than that in adult. Significantly enhanced phosphorylation of STAT3 was seen in neonatal macrophages. Both mRNA and protein expression of SOCS3 in neonatal macrophages were lower than that in adult. After pretreated with MG132, the expression of SOCS3 protein was increased which lead to attenuate the STAT3 phosphorylation and APP gene expression. CONCLUSION: Neonatal exhibit an enhanced expression of downstream target genes and IL-6/STAT3 signal pathway which is related with the diminished SOCS3. This provides a new sight into inflammatory responses in neonatal.
Subject(s)
Acute-Phase Proteins/genetics , Acute-Phase Proteins/metabolism , Interleukin-6/metabolism , Suppressor of Cytokine Signaling 3 Protein/genetics , Suppressor of Cytokine Signaling 3 Protein/metabolism , Adult , Gene Expression Regulation , Humans , Macrophages/metabolism , Monocytes/metabolism , RNA, Messenger/genetics , STAT3 Transcription Factor , Signal Transduction/genetics , Young AdultABSTRACT
The relationship between breastfeeding and infant health has been well elucidated in past decades. Our previous study has shown that human ß-defensin 1 (hBD-1) in human breast milk plays a protective role in reducing the incidence of upper respiratory infection in infants younger than 6 months. In the present study, we aim to reveal the mechanism underlying the protective role of hBD-1 by focusing on its immunoregulatory function in neonates. Cord blood (CB) from newborns' umbilical cords, which can simulate many of the neonatal symptoms, was used to study the immunomodulatory role of hBD-1 in neonates in vitro. Our results showed that hBD-1 promotes the GM-CSF- and IL-4-driven differentiation of neonatal umbilical CB monocytes to immature dendritic cells (DCs) and the final maturation of CB monocyte-derived DCs (moDCs) induced by LPS but not inflammatory cytokine production. In addition, hBD-1 inhibits apoptosis in neonatal moDCs through CCR6, which might be a possible mechanism of the hBD-1-induced phenotypes in moDCs. Furthermore, we found that hBD-1 promotes the proliferation and activation, but not the maturation, of neonatal CB CD4 + T cells. These results extend the immunoregulatory effects of hBD-1 and provide a potential mechanism for the protective role of hBD-1 in early infants, which will inform the development of infant nutrition, novel vaccines and anti-infective strategies in the future.
Subject(s)
Dendritic Cells/cytology , Fetal Blood/cytology , T-Lymphocytes/cytology , beta-Defensins/immunology , Apoptosis , Biomarkers/metabolism , Cell Differentiation , Cell Proliferation , Cytokines/biosynthesis , Dendritic Cells/metabolism , Endocytosis , Humans , Infant, Newborn , Lipopolysaccharides , Lymphocyte Activation/immunology , Monocytes/cytology , Monocytes/metabolism , Receptors, CCR6/metabolism , T-Lymphocytes/metabolismABSTRACT
BACKGROUND: The uncontrolled inflammatory response following infection is closely related to the morbidity and mortality of neonates. Interleukin 6 (IL-6) plays an important role in the pathogenesis and prognosis of this process. To better elucidate the secretion of IL-6 following infection in neonates, we investigated the IL-6 level and mechanism of IL-6/TLR4 signaling pathways. METHODS: We compared the IL-6, procalcitonin (PCT), and CRP levels between septic neonates and toddlers. In vitro cord blood samples from healthy term neonates and peripheral venous blood from healthy adult volunteers were collected. Protein expression was analyzed by Western blotting, mRNA expression by real-time PCR and membrane molecule expression by flow cytometry. RESULTS: The IL-6 concentrations were significantly higher in the neonate group than in the toddler group (p < 0.05). In the toddler group, the IL-6 concentrations were correlated positively with both PCT and CRP (PCT: r = 0.451, p = 0.001; CRP: r = 0.243, p = 0.023). In vitro, the secretion of IL-6 increased with the rising concentrations of LPS; at 1000 ng/ml LPS, IL-6 secretion from the monocytes of neonates was significantly higher than that of adults. There was a marked decreased level of MyD88 in neonate monocytes compared with that in adult monocytes. Additionally, the mRNA levels of Zc3h12a in neonate monocytes were significantly lower than those in adult monocytes following LPS stimulation. CONCLUSION: Neonates displayed enhanced IL-6 production after infection. Our study, for the first time, reported a significant decrease in the expression of Zc3h12a in neonates. Thus, Zc3h12a may be a key factor for the aberrant increase in IL-6 after neonate infection.