The effect of environmental factors on the differential expression of miRNAs in patients with chronic obstructive pulmonary disease: a pilot clinical study

Objective The objective of the study was to analyze the effect of environmental factors on the differential expression of microRNAs in the peripheral blood of migratory and local patients in northern People's Republic of China and on clinical symptoms of local patients in northern People's Republic of China with COPD. Methods A total of 118 patients in the northern region and 8 migratory patients were enrolled in this prospective study. We collected general information. Blood samples were collected from 9 patients in the Beijing group, from 8 patients in the migratory group and from 9 healthy control subjects. After extracting the total RNA from these 3 groups, serum miRNA was identified by Solexa sequencing. We collected COPD assessment test (CAT) and Modified British Medical Research Council (mMRC) scores at different levels of air pollution and also collected the number of exacerbations over the year prior to the baseline and in the year preceding the follow-up. Results In total 9 miRNAs were differentially expressed. When air quality index (AQI) >100, the CAT and mMRC scores at baseline were significantly higher than those when the AQI ≤100 (P<0.001). When AQI >100, the follow-up CAT and mMRC scores were significantly higher than those when AQI ≤100 (P<0.001). Follow-up mMRC scores were significantly higher than baseline scores (P=0.04). When AQI ≤100, the baseline CAT score of the group with fewer symptoms was 6.50 (4.00-8.75). However, when AQI >100, the baseline CAT score of this fewer symptoms group was 10.00 (6.25-12.00). The median CAT score was close to 10. When AQI ≤100, the follow-up CAT score of the fewer symptoms group was 8.00 (4.25-12.00). However, when AQI >100, the follow-up CAT score of the fewer symptoms group was 9.50 (6.00-16.75). The median CAT score was close to 10. Conclusion Environmental factors may cause differential expression of miRNAs in the peripheral blood of migratory and local patients in northern People's Republic of China. Air pollution may aggravate clinical symptoms of patients with COPD.