The Significance And Functional Analysis Of Notch Ligand DLL4 Expression In The Peripheral Blood Of Children With Mycopiasma Pneumoniae Pneumonia

Objective: To understand the role of the Notch signaling pathway in the pathogenesis of Mycopiasma Pneumoniae Pneumonia(MPP)through analyzing the expression of Notch ligands in peripheral blood mononuclear cells of children with Mycoplasma pneumoniae pneumonia.Methods:One hundred and twenty-eight hospitalized MPP children were enrolled from March 2015 to July 2016 in Children's Hospital of Soochow University,including 76 mild cases and 52 severe cases.In the same period,thirty-five hospitalized children for surgical elective surgery were collected as control group.Meanwhile,clinical data and laboratory findings were also collected.To detect the expression of Jagged1,Jagged2,DLL1 and DLL4 by using RT-PCR methods.Flow Cytometric detection of peripheral blood CD3+cells,CD3+CD4+ cells,CD3+CD8+ cells and CD3-CD19+ cells proportion of lymphocytes.Serum levels of IFN-?,IL-4,IL-10,IL-17 and IL-36? were detected by enzyme-linked immunosorbent assay(ELISA).We analyzed the relationship between DLL4 and the Lymphocyte subsets,the related cytokines and the clinical index of MPP.Results:(1)MPP cases presented respiratory system symptoms such as fever,cough,etc.However,the children with severe MPP were older than children with mild MPP(5.50 y vs 3.24 y,P=0.000),duration of fever was longer than that of mild MPP(6.72 d vs 2.58 d,P=0.000),as well as longer duration of hospital days in severe MPP cases(8.56 d vs7.34 d,P=0.027);The White blood cell count,percentage of neutrophils and C-reactive protein(CRP)concentration were higher in cases with severe MPP compared to mild MPP cases(P=0.006,0.005 ? 0.000);Lober pneumonia was common in children with severe MPP and these cases often presented pleural effusion.Otherwise,lobular pneumonia was common in cases with mild MPP.(2)The expression level of mRNA of Notch ligand DLL4 in peripheral blood of MPP group was significantly higher than that in the control group(P=0.000).However,there were no significant differences in Jagged1,Jagged2 and DLL1 expression between those groups(both P>0.05);The expression level of mRNA of Notch ligand DLL4 in peripheral blood of severe group was significantly higher than that in the mild group(P=0.034).However,there were no significant differences in Jagged1,Jagged2 and DLL1 expression between the two groups(both P>0.05).(3)The levels of peripheral CD3+ cells and CD3+CD4+ cells in the MPP group were substantially lower than those in the control group,whereas the levels of peripheral CD3+CD8+ cells and CD3-CD19+ cells were significantly higher in the MPP group(both P<0.001);The levels of peripheral CD3+ cells and CD3+CD4+ cells in the severe MPP group were significantly lower than those in the mild group(P=0.009 and 0.006),whereas the levels of peripheral CD3+CD8+ cells and CD3-CD19+ cells were significantly higher in severe MPP group compared to the mild group(P=0.027 and 0.002).(4)The serum levels of IFN-?,IL-17 and IL-36? in the MPP group were higher than those in the control group(both P<0.001),whereas the levels of IL-4 and IL-10 in the MPP group were lower than those in the control group(P=0.003 and 0.002);The serum levels of IFN-?,IL-17 and IL-36? in the severe MPP group were higher than those in mild MPP group(P=0.000,0.011 and 0.000).However,there were no significant differences in IL-4 and IL-10 expression between the two groups(P=0.955 and 0.810).(5)The expression of Notch ligand DLL4 in the peripheral blood of the MPP group correlated positively with the duration of hospital days and the White blood cell count(r=0.232 and 0.183,P=0.008 and 0.039),but there were no correlations between the level of DLL4 and the duration of fever,percentage of neutrophils,C-reactive protein(CRP),IgG,IgA and IgM(both P>0.05).(6)The expression of Notch ligand DLL4 in the peripheral blood of the MPP group correlated negatively with the levels of peripheral CD3+ cells and CD3+CD4+ cells(r=-0.199 and-0.276,P=0.002 and 0.024),but correlated positively with the levels of peripheral CD3+CD8+ cells(r=0.277,P=0.002).There were no correlation between the level of DLL4 and peripheral CD3-CD19+ cells(r=0.013,P=0.880).(7)The expression of Notch ligand DLL4 in the peripheral blood of the MPP group correlated positively with the levels of IFN-? and IL-17(r=0.176 and 0.194,P=0.047 and 0.028).There were no correlations between the level of DLL4 and the levels and IL-4,IL-10 and IL-36?(r=-0.027,-0.089and-0.127;P=0.766,0.320and0.154).Conclusion:The level of DLL4 was abnormally high expressed in MPP group,and the severe group had higher level.The Notch ligand DLL4 exhibited correlation with the levels of the CD3+ cells,CD3+CD4+ cells and CD3+CD8+ cells and the levels of IFN-? and IL-17 in children with MPP,indicating that Notch signaling pathway plays an important role in the immune inflammatory mechanism of mycoplasma pneumoniae infection by affecting the function of immune cells and regulating the differentiation of Th1 and Th17 cells.This further enriches the immunological pathogenesis of MPP,and provides a new way for the treatment of the disease.