SPP1 and Patent ductus arteriosus: Overall, we found that, consistent with other reports (23, 28), PDA TAMs displayed a more alternatively activated (M2-like) polarization with the expression of genes associated with the M2 phenotype and immunosuppression such as SPP1, CD163, CXCR4, HIF1, TGF-β1, and multiple MHCII molecules (Figure 1C).