IL13 and asthma: On the other hand, although our gene expression results did not revealed POSTN as a differential gene, we decided to include the analysis of periostin levels in the serum, as it is one of the main biomarkers described as indicator of Th2-inflammation (41, 42) and the serum periostin levels have been related to the response to anti-IL-13 therapy in patients with moderate–mild asthma (43).