Abstract
ObjectivesMycoplasma pneumoniae is a leading cause of community-acquired pneumonia in children. However, its mechanism of pathogenesis is not fully understood, and microRNAs might play a role. This study aimed to explore the microRNA-222-3p (miR-222-3p) expression and its possible role in children with M.pneumoniae pneumonia (MPP).MethodsThirty-six children with MPP and twenty-seven age-matched controls from Children’s Hospital of Soochow University were enrolled in this study. MiR-222-3p and cluster of differentiation 4 (CD4) mRNA were detected using real-time PCR in children’s peripheral blood plasma samples. THP-1 cells and mice were stimulated with M.pneumoniae lipid-associated membrane proteins(LAMPs).ResultsChildren with MPP had significantly higher levels of miR-222-3p and lower levels of CD4 in peripheral blood plasma (P < 0.05). Additionally, Sixteen children with MPP complicated with pleural effusion had higher miR-222-3p levels than those without pleural effusion. MiR-222-3p or CD4 in THP-1 cells increased or decreased, respectively, in a dose dependent manner after LAMP stimulation. In LAMP-stimulated mice massive inflammatory cells infiltrates surrounded the bronchioles, and miR-222-3p increased in the bronchoalveolar lavage fluid. In conclusion, miR-222-3p was highly expressed in children with MPP, especially those with pleural effusion.ConclusionSmall sample studies showed that M.pneumoniae or its LAMPs could increase miR-222-3p and decrease CD4 in macrophages,both in vitro and vivo.Thus, miR-222-3p might be an MPP biomarker for the diagnosis and prognosis.
Highlights
Mycoplasma pneumoniae is an important cause of community-acquired pneumonia (CAP) in children and young adolescents, accounting for 20 to 40% of CAP in children [1]
Comparisons of miR-222-3p and cluster of differentiation 4 (CD4) levels between M. pneumoniae pneumonia (MPP) cases and controls According to the Target Scan 7.1 database, CD4 is one of the direct targets of miR-222-3p
Children with MPP had significantly higher levels of miR-222-3p in tneir peripheral blood mononuclear cells compared with controls (1.5 ± 0.2 vs. 1.0 ± 0.2, relative expression) and lower levels of CD4 mRNA (0.5 ± 0.2 vs. 1.0 ± 0.4, relative expression)(Fig. 2)
Summary
Mycoplasma pneumoniae is an important cause of community-acquired pneumonia (CAP) in children and young adolescents, accounting for 20 to 40% of CAP in children [1]. Some pathogenic factors of M. pneumoniae, such as hydrogen peroxide, Community-Acquired Respiratory Distress Syndrome (CARDS) toxin, nuclease and lipid-associated membrane proteins (LAMPs), have been reported to be associated with the development of pneumonia [2,3,4,5]. These pathogenic factors are insufficient to explain the pathogenic mechanism of M. pneumoniae pneumonia (MPP) in children. Target gene prediction analysis of miR222-3p was performed by Targetscan, Pictar, and miRDB databases to determine that CD4 molecule is a potential target gene of miRNA-222-3p
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