The researchers found that the expression of mRNA-encoding TSLP, TARC/CCL17, MDC/CCL22 and IP-10/CXCL10, other than I-TAC/CXCL11 and I-309/CCL1, were significantly increased in severe asthma and COPD patients compared to the non-smoking control group. This evidence concerns the gene CCL1 and asthma.