Objective: This study detected the expressions of microRNA-26a (miR-26a), miR-146a and miR-31 in lung tissues and BALF (bronchoalveolar lavage fluid) of asthma mice and children. Besides, cytokine levels of interleukin-5 (IL-5), IL-8, IL-12 and tumor necrosis factor-α (TNF-α) were detected as well. We aim to provide an experimental basis for clinical treatment of asthma.
Patients and methods: Forty female BALB/c mice were randomly assigned into control group and asthma group, respectively. Mice in asthma group (n=20) were immunized by intraperitoneal injection of OVA (ovalbumin) and provoked by atomization inhalation of OVA from the 15th day for 10 days. Mice in control group (n=20) were immunized and provoked with isodose saline during the same period. At the 26th day, mice were sacrificed for collecting lung tissues and BALF. Besides, we enrolled 17 cases of asthma children and 13 cases of children with airway foreign body as controls. BALF of each subject was collected. Total cellular score and differential counting in BALF were recorded. Expression levels of miR-26a, miR-146a, and miR-31 were detected by reverse transcription-polymerase chain reaction (RT-PCR). Levels of IL-5, IL-8, IL-12, and TNF-α were detected by enzyme-linked immunosorbent assay (ELISA).
Results: The total cellular score in BALF of asthma mice and asthma children was higher than that of controls (p<0.05). Percentages of eosinophils, neutrophils, and lymphocytes in BALF of asthma mice and asthma children were higher than those of controls, whereas the percentage of macrophages was lower (p<0.05). Levels of IL-5, IL-8, IL-12, and TNF-α in lung tissues of asthma mice were markedly elevated compared with those of controls (p<0.05). Similarly, levels of IL-5, IL-8, IL-12, and TNF-α were higher in BALF of asthma children than controls (p<0.05). RT-PCR data showed higher mRNA levels of miR-26a, miR-146a, and miR-31 in lung tissues of asthma mice than controls (p<0.05). The mRNA levels of miR-26a, miR-146a, and miR-31 in BALF of asthma children were highly expressed compared with those of controls as well (p<0.05).
Conclusions: MiR-26a, miR-146a, and miR-31 are involved in asthma progression mainly through regulating inflammatory factors and cells.