Clinical Characteristics, Early Intervention And TIPE2-mediated Regulation Of Refractory Mycoplasma Pneumoniae Pneumonia

Part I Clinical Characteristics of Refractory Mycoplasma Pneumoniae PneumoniaObjective:Although MP infection was traditionally thought to be a self-limited process, more and more severe cases even fatal cases of MP infections were reported in recent years, it may sometimes cause various pulmonary and extra-pulmonary complications, such as pleural effusion, pulmonary atelectasis, consolidation, encephalitis, pericarditis and anemia, and progress to a severe life-threatening pneumonia. So it is important for physicians to recognize refractory Mycoplasma pneumoniae pneumonia (RMPP) earlier and give proper therapy. The aim of this study is to analyze the clinical characteristics of RMPP, and study the critical values of the independent correlation factors of RMPP.Methods:Retrospective analysis was performed on the clinical data of708children with Mycoplasma pneumoniae pneumonia (MPP). The patients were divided into "general MPP group" and "RMPP group" according to the signs and symptoms. The clinical manifestations, laboratory examination, radiological features of the children were compared. In order to seek the reference indexes which indicate refractoriness, an ROC curve was made, of which the diagnostic cut-off was seven independent correlation factors while grouping was made.Results:The general MPP group had508children (508/708,71.8%) while MPP group had200(200/708,28.2%). The RMPP group children had the following performances:The age of children in RMPP group were older than that in general MPP group (P<0.001). The incidence of fever, high-grade fever, chest tightness, tachypnea, decrease in breath sound and extra-pulmonary complications were significantly higher compared to those in general MPP group, which needs more oxygen and BAL therapy. The median fever duration prior to admission was7(3-9) days and10(8-12) days, the median total fever duration was7(3～10) days and and14(12～17) days, and the median hospitalization duration was6(4-7) days and9(7-12) days, respectively in the general MPP group and the RMPP group (P<0.001). The levels of C-reactive protein (CRP), procalcitonin (PCT), actic dehydrogenase (LDH), immunoglobulin M (IgM), IgA, interleukin (IL)-6, IL-10, IFN-y and the percentage of neutrophils, CDs+in RMPP group were significantly higher than those in general MPP group (P<0.001); while the percentage of lymphocytes and the ratio of CD4+to CD8+were lower than those in general MPP group (P<0.001). Radiological manifestations:large lesions and pulmonary complications, such as pleural effusion, atelectasis, consolidation and necrotizing pneumonia were more frequently seen in RMPP group than those in general MPP group (P<0.001). The critical values of the seven independent correlation factors were N%66.1%, L%3.4%, CRP12.5mg/L, PCT0.125ng/ml, LDH437IU/L, IL-610.65pg/ml and IL-105.65pg/ml.Conclusions:Children with RMPP are older than children with general MPP, and RMPP may lead to more complications, severe clinical features, radiological manifestations, and needs more oxygen and BAL therapy. MPP maybe progress into RMPP in some situations such as N%≥66.1%, L%≤23.4%, CRP>12.5mg/L, PCT≥0.125ng/ml, LDH>437IU/L, IL-6≥10.65pg/ml and IL-10>5.65pg/ml. Part II Effects of Early Bronchoalveolar Lavage on Refractory Mycoplasma Pneumoniae Pneumonia with Large Pulmonary Lesions in ChildrenObjective:Nowadays, flexible bronchoscopy (FOB) with bronchoalveolar lavage (BAL) is an important and indispensable tool to assess the structure and function of lower airways, diagnose pulmonary infiltrative lesion in pediatric patients. Furthermore, endobronchial tuberculosis could be excluded earlier. Additionally, FOB could also perform therapeutic interventions, such as treating acute lung collapse and atelectasis which was refractory to conventional therapy. To our knowledge, this is the first study to focus on the effect of BAL in RMPP patients in a prospective fashion. The aim of this study is to prospectively evaluate the effect of early BAL on refractory Mycoplasma pneumoniae pneumonia (RMPP) with radiologically proved large pulmonary lesions in children.Methods:A total of35children diagnosed as RMPP with radiologically proved large pulmonary lesions completed the study. According to the time point of BAL, they were divided into two groups. The early BAL group:BAL was performed within three days after admission (n=22), and the late BAL group:BAL was performed three days later after admission (n=13). Clinical effect was compared between these two groups.Results:After BAL therapy, improvement in clinical symptoms, laboratory findings as well as resolution of pulmonary lesion on radiography were obtained in all subjects. The median fever duration after admission was4(3-5) days and7(6-8) days (P<0.05), and the median hospitalization duration was5(4-6) days and10(7-12) days (P><0.05), respectively in the early BAL group and the late BAL group. About7days after admission,66.7%of subjects in the early BAL group showed resolution of atelectasis on X-ray image versus a corresponding rate of14.3%in the late BAL group (P<0.05). Furthermore, laboratory indices recovered quicker in the early BAL group than those in the late BAL group (P<0.01).Conclusions:BAL appeared to be efficacious and well-tolerated treatment for RMPP with radiologically proved large pulmonary lesion, and early application of BAL may be more beneficial. Part Ⅲ The negative role and its underlying mechanism of TIPE2on Mycoplasma Pneumoniae infectionObjective:The morbidity and mortality of Mycoplasma Pneumoniae (MP) infection increased annually, comprising a serious threat to children’s health. Recently, studies showed that TLR signaling pathways played an important role in inflammation induced by mycoplasma pnuemonia. Tumor necrosis factor-a-induced protein8-like2(TIPE2), a member of the tumor necrosis factor-a-induced protein-8(TNFAIP8) family is a negative regulator of TLR, and could prevent hyperresponsiveness and maintain immune homeostasis. However, the effect and underlying mehcanisms of TIPE2on MP infection remain unclear. This study will investigate the influence of MP infection on the protein levels of TIPE2expression, and explore the effect and its underlying mechanisms regulating MP infection response by TIPE2.Methods:We collected the peripheral blood monouclear cells from130children with Mycoplasma Pneumoniae pneumonia (MPP), which were divided into general MPP group and Refractory Mycoplasma Pneumoniae pneumonia (RMPP) group according to the clinical manifestation, and detected the levels of TIPE2mRNA. We also detected the levels of TIPE2in macrophages in vitro after MP infection. Meanwhile, we interfered the TIPE2expression in macrophage, study the production of cytokines, such as TNF-a, IL-6and IL-1β, and detected the changes of signal pathway after MP infection.Results:In our study, we found that TIPE2were downregulated in peripheral blood monouclear cells of children with MP infection, which were correlated with the degree of severity of MPP. In vitro, we also found the expression of TIPE2was downregulated and cytokines, such as TNF-a, IL-6and IL-1β were produced after MP infection. Through loss of function, we found the production of TNF-a, IL-6and IL-1β were upregulated, and the signal pathway of MAPK was activated.Conclusions:Our data showed that TIPE2were downregulated in peripheral blood monouclear cells of children with MP infection and in macrophages in vitro, and knockdown of TIPE2in macrophage significantly promoted the production of TNF-a, IL-6and IL-1β through inhibiting the MAPK signal pathway. The results will provide insights into the molecular events controlling the MP infection.