We performed proteomics analysis of a set of five very small skin and muscle tissue samples collected from three distinct ancient Egyptian mummies of the Old Kingdom (ca. 2200-200 BC). This is one of the first examples of using bioarchaeological proteomics data to uncover clues about life and death in ancient Egypt.
In contrast to most shotgun proteomics experiments, the issue in this work is not managing mountains of data. The proteins in the tissue samples are thoroughly degraded, as evidenced by the extensive smearing present when visualising SDS page gels. This is confirmed by the low number of peptides and proteins identified in the samples. There are typically less than 50 proteins reproducibly identified, whereas a similar analysis of modern human skin samples identifies hundreds of proteins.
We found a large number of keratins and collagens, which was in agreement with our microscopy data, and previous studies showing that collagens are very long-lived. Using nanoflow high-performance liquid chromatography–mass spectrometry of extracted peptides, we identified a total of 230 proteins from the five tissue samples, which consisted of 132 unique protein identifications. We identified numerous proteins indicative of activation of the innate immune response in two of the mummies, one of which also contained proteins indicating severe tissue inflammation, possibly indicative of a lung infection that we can speculate may have been related to the cause of death. The data also suggests that this person may have suffered from chronic inflammatory condition before they died. Taken together, our data provide molecular evidence that certain diseases common in current society were also present in ancient cultures. While sample materials remain incredibly scarce, this study provides a good idea of the level of information which can be produced by such analyses, which will hopefully stimulate further research in the field.