Both hsa-let-7a (differentially expressed in patients with severe asthma42) and hsa-let-7b play important roles in asthma by targeting pro-inflammatory pathways.29 We found two meta-paths, including hsa-let-7a-CASP3-CCND1-hsa-mir-20a and hsa-let-7b-CCND2-FOXO4-hsa-mir-499a between asthma and COPD, via mpDisNet (Fig. 7). The gene discussed is CASP3; the disease is chronic obstructive pulmonary disease.