Expression of Serum miR-155 in Children with Mycoplasma pneumoniae Pneumonia and Its Role in Immunity to Mycoplasma pneumoniae

OBJECTIVE: To investigate the expression of serum miR-155 in children with Mycoplasma pneumoniae pneumonia (MPP). METHODS: A total of 100 children at our hospital with pneumonia caused by Mycoplasma pneumoniae infection were enrolled as a study group, including 45 cases in the acute phase (acute phase group) and 55 in the recovery phase (recovery phase group). An additional 30 healthy children were enrolled during the same period as the control group. The expression levels of miR-155, tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), IL-10, IL-13, immunoglobulin (Ig) G, IgA, complements (C3 and CH50), and T lymphocyte subsets (CD(3)(+), CD(4)(+), CD(8)(+), and CD(4)(+)/CD(8)(+)) were determined. Multivariate logistic regression analysis was performed to identify risk factors affecting MPP in children. RESULTS: miR-155, IL-10, IgG, IgA, CD(3)(+), CD(4)(+), and CD(4)(+)/CD(8)(+) were poorly expressed in children with MPP, and their expression in the acute phase group was significantly lower than that in the recovery phase group. TNF-α, IL-13, C3, and CH50 were highly expressed in the children, and their expression was significantly higher in the acute phase group than in the recovery phase group. In the acute phase group, the expression of IL-8 was significantly higher than that in the control and recovery phase groups but without any significant differences between the recovery phase and control groups. Age, season, low complement state, epidemiological contact history, and antibiotic use time were independent risk factors affecting MPP in children. CONCLUSION: Serum miR-155 is poorly expressed in children with MPP, and it can regulate inflammatory disorders and immune responses.