The Expression And Possible Mechanism Of MiR-222-3p In Peripheral Blood Of Mycoplasma Pneumoniae Pneumonia

Objective: To identify the differentially expressed micro RNAs(mi RNA)in plasma of Mycoplasma pneumoniae pneumonia(MPP) by microarray. Investigate the expression of mi R-222-3p and CD4 molecule in peripheral blood. To explore the possible regulation of mi R-222-3p involved in the immune response of Mycoplasma pneumoniae pneumonia.Methods: 1. 36 cases of hospitalized children with Mycoplasma pneumoniae pneumonia(MPP group) were collected from March 2014 to June 2015 in Children’s Hospital Affiliated to Soochow University. 27 cases of healthy chidren were collected as control group(NC group) in the same period.2. Mi RNA microarray chip was used to find out differentially expressed mi RNAs of plasma from 3 cases with MPP group and 3 cases with NC group.3. The target genes of mi R-222-3p were predicted by biological software.4. Real-time quantitative PCR(RT-q PCR) was choosen to detect the expression of mi R-222-3p and its potential target gene CD4 in leukocytes from MPP group(n=36) and NC group(n=27), and the relationship between mi R-222-3p and CD4 was analyzed.5. The lipid-associated membrane proteins(LAMPs) were extracted from Mycoplasma pneumoniae strains. THP-1 cells were stimulated with different concentrations of LAMPs. The cell damage degree was observed, and the expressions of mi R-222-3p and CD4 from THP-1 cells were under the action of RT-q PCR assay. Analysis the correlation between the four factors: the level of mi R-222-3p, CD4, the concentrations of LAMPs and the degree of cell damage.Results: 1. mi RNA microarray assays screen out 26 mi RNAs in a statistically significant way, of which 19 mi RNAs elevated, 7 mi RNAs declined.2. CD4 was one of the target genes of mi R-222-3p.3. Compared with NC group, the expression of mi R-222-3p increased(p<0.01) and the expression of CD4 decreased in the MPP group(p<0.01). There was no correlation between the level of mi R-222-3p and CD4.4. The LAMPs of Mycoplasma pneumoniae induced THP-1 cell damage, in which the more concentration of LAMPs the worse damage of the cell.5. Compared with the blank group, the expression of mi R-222-3p was up-regulated in each LAMPs stimulated group and there was a statistically significance(P<0.01). The expression of CD4 was down-regulated in the LAMPs stimulated group(P < 0.01). Moreover, the expression of mi R-222-3p was positively correlated with the level of LAMPs. There was no correlation between the level of CD4 and mi R-222-3p, LAMPs.Conclusions: 1. Mi RNAs participated in the immunopathogenesis of Mycoplasma pneumoniae pneumonia.2. The expression of mi R-222-3p in the peripheral blood of Mycoplasma pneumoniae pneumonia was raised and CD4 was reduced, mi R-222-3p was involved in the immune response after infection with Mycoplasma pneumoniae by inhibiting the expression of CD4.3. Mi R-222-3p regulating the expression of CD4 participated in the THP-1 cell damage induced by lipid-associated membrane proteins of Mycoplasma pneumoniae.