3.4 PPI network and hub gene
The resulting PPI networks were constructed by 173 significant DEGs (Fig.3), constituted by 166 nodes and 334 edges in total. In a PPI network, the genes which have more edges are known to play more important roles (like a seed). The ”Degree” was used to count edge numbers of every gene in a PPI network. The top 10 genes, which were identified as hub genes, are shown in Table 3. Interestingly, all of 10 hub genes, such as CD19, CD79B, CD74 and CD72 were observed to be upregulated in the blood of infants with BPD compared with normal preterm infants. These genes were also shown to be related to the downstream signaling events of the B cell receptors and of the hematopoietic cell lineage.