This review summarizes the results of a series of studies performed by our group with the aim to define the expression levels of thymosin β4 and thymosin β10 over time, starting from fetal development to different ages after birth, in different human organs and tissues. The first section describes the proteomics investigations performed on whole saliva from preterm newborns and gingival crevicular fluid, which revealed to us the importance of these acidic peptides and their multiple functions. These findings inspired us to start an in-depth investigation mainly based on immunochemistry to establish the distribution of thymosin β4 and thymosin β10 in different organs from adults and fetuses at different ages (after autopsy), and therefore to obtain suggestions on the functions of β-thymosins in health and disease. The functions of β-thymosins emerging from these studies, for instance, those performed during carcinogenesis, add significant details that could help to resolve the nowadays so-called “β-thymosin enigma”, i.e., the potential molecular role played by these two pleiotropic peptides during human development.
