An expanded self‐antigen peptidome and proteome is carried by the human lymph as compared to the plasma

Abstract

The pre‐nodal afferent lymph is the fluid which directly derives from the extracellular milieu from every parenchymal organ and, as it continues to circulate between the cells, it collects products deriving from the organ metabolism/catabolism. Herein, we showed a major difference between lymph and plasma that could be visualized by FPLC and 2D gel in the amount of low molecular weight products corresponding to peptide fragments with MW<5000 Da. Analysis of more than 300 sequences identified self‐peptides derived from both intracellular and extracellular proteins revealing the variety of catabolic products transported by human lymph. Moreover, an advanced proteomics analysis of the afferent pre‐nodal lymph in parallel to matched human plasma from healthy donors was performed using two proteomics strategies: 1D gel LC‐MS/MS analysis, and 2‐D‐DIGE coupled with mass spectrometry nanospray LC‐MS/MS. Scaffold 3.0, combined with Ingenuity Pathway analysis, highlights the proteomic functional signature of the prenodal lymph and plasma. The distinctive proteome of the human lymph is characterized by several products derived from the processing of extracellular matrix as well as cellular catabolism, metabolism and apoptosis. Whereas the distinctive plasma proteome is mostly represented by soluble molecule of the coagulation system and cell‐cell signaling factors.