| Objective: To analyze the serum levels of soluble B7-H3(s B7-H3) and related inflammatory factors in children infected with Mycoplasma Pneumoniae Pneumonia(MPP) and explore the role of costimulatory molecule B7-H3 in the inflammatory machanisms of children with MPP.To study the inflammatory cytokines in bronchoalveolar lavage fluid(BALF), pathological changes in lung tissue and the therapeutic implications of dexamethasone through stimulating the mice with lipid-associated membrane protein(LAMPs) of mycoplasma pneumoniae and intervening with dexamethasone.Methods: One hundred and eight hospitalized MPP children were enrolled from January 2015 to December 2015 in Children’s Hospital of Soochow University, including 52 mild cases and 56 severe cases. In the same period, forty hospitalized children for surgical elective surgery were collected as control group. Serum levels of s B7-H3, IFN-γ, IL-4, IL-17, IL-36α and GM-CSF were detected by enzyme-linked immunosorbent assay(ELISA). We analyzed the relationship between s B7-H3 and the related cytokines and the relationship between s B7-H3 and the severity of MPP. Mice were stimulated with LAMPs(group P), while the other two groups were intervened with dexamethasone(group D) and saline(group N). The mice BALF were collected at 12 h, 24 h and 48 h after stimulating to count the total cell. The levels of IFN-γ, IL-4, IL-17 and GM-CSF in the BALF were detected by ELISA. Mouse lung tissue sections were stained with HE and immunohistochemical method(SABC method) to observe the infiltration of inflammatory cells and the expression of B7-H3 in lung tissue.Results: The levels of s B7-H3, IFN-γ, IL-17, IL-36α and GM-CSF in plasma in acute phase of MPP group were at high levels(P<0.001), and decreased after treatment. However, the levels of s B7-H3, IFN-γ, IL-36α and GM-CSF in MPP group after treatment were still higher than the control group(P<0.05). The level of IL-4 was at low level(P=0.014), and not significantly increased after treatment(P=0.067). The serum levels of s B7-H3, IFN-γ, IL-17, and GM-CSF in acute phase of severe MPP group were higher than those in mild MPP group(P<0.05). The levels of s B7-H3 had positive correlation with the levels of IFN-γ and GM-CSF(r=0.744 and 0.703,P<0.001), while the levels of s B7-H3 had no significant correlation with the levels of IL-4, IL-17 and IL-36α(r=0.167, 0.181 and 0.035,P>0.05).There were no significant differences in the total cells in mice BALF, cytokine expression, lung tissue pathological stained and immunohistochemistry B7-H3 at 12 h and 24 h among the three groups(P>0.05). The total cells in BALF in group P were significant more than the group D and group N at 48h(P<0.05) and the total cells in BALF in group D were significant higher than the group N(P=0.004). The levels of IFN-γ, GM-CSF, IL-4 and IL-17 in group P were higher than group N at 48h(P<0.05), while the levels of IFN-γ and GM-CSF were higher than group D(P=0.025 and 0.037). The levels of IL-4 in group D were higher than group N(P=0.004), while the levels of IFN-γ, GM-CSF and IL-17 in group D and group N were no statistically significant(P>0.05). Lung tissue pathological stained showed more infiltration of inflammatory cells(lymphocytes, macrophages) around the airway and alveolar in group P at 48 h, while the infiltration of inflammatory cells reduced in group D and nearly no significant infiltration of inflammatory cells in group N. Immunohistochemistry showed the expression of B7-H3 in group P were significant higher than group D and group N(P<0.05). The expression of B7-H3 in group D were significant higher than group N(P=0.004). Normal saline control group did not express B7-H3.Conclusion:(1)The levels of s B7-H3 was abnormally high expressed in acute phase of MPP, and the levels of s B7-H3 had positive correlation with the levels of IFN-γ and GM-CSF, suggesting that s B7-H3 play an important role in post-infectious inflammation of MPP mainly through regulating Th1 cell-mediated immune responses and neutrophil proliferation.(2)The serum levels of s B7-H3 in severe MPP group were higher than those in mild MPP group suggesting that the levels of s B7-H3 may be related to the severity of MPP. Monitoring the levels of s B7-H3 is useful in assessing disease progression and prognosis.(3) Stimulating the mice with MP lipid-associated membrane protein can cause lung inflammation, and the inflammation can be reduced by the administration of dexamethasone. This suggesting that early use of steroid therapy play an important role in the control of body inflammation. |
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