*3.4. Angiopoietin (Ang)-2*

The angiopoietin family includes Ang-1, Ang-2, Ang-3, and Ang-4 types, which are vital for embryonic angiogenesis. These growth factors are ligands for the vascular endothelial receptor tyrosine kinase (Tie-2), required for vascular activation [38]. Mbhele et al. (2017) demonstrated that, in contrast to PlGF, increased levels of Ang-2 and Eng were noted in PE. The gestational period (early- or late-onset PE) had no effect on Ang-2 expression; yet, it was associated with Eng (*p* < 0.0001) and PlGF (*p* = 0.0033). HIV infection did not affect Ang-2 (*p* = 0.4), Eng (*p* = 0.4), and PlGF (*p* = 0.7) levels [39].
