Comparative proteomic analysis of rodent plasma and mesenteric lymph

The lymph has long been considered as the plasma filtrate and the proteomes of the lymph have received scanty attention. Currently, mesenteric lymph is reported to play an important role in the pathogenesis of multiple organ dysfunction syndrome in some critical illnesses. A better understanding of the composition and proteomes of mesenteric lymph becomes imperative to disclose the mechanistic role of mesenteric lymph. Seven male Sprague-Dawley rats were fasted overnight, and anesthetized to collect plasma and mesenteric lymph. The specimens were subjected to proteomic analysis using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). An average of 434 and 412 protein spots were found in the gels of the plasma and mesenteric lymph respectively. Peptide mass fingerprint analysis identified 77 proteins for 212 protein spots. The 2-DE proteomic pattern of mesenteric lymph was largely similar to that of the plasma. As in the plasma, large protein spots of albumin dominated the protein pattern in mesenteric lymph. Other major proteins identified in 2-DE gels included immunoglobulin heavy and light chains, fibrinogen alpha-, beta- and gamma-chains, serotransferrin, protease inhibitors, kininogens, macroglobulins, haptoglobin, and apolipoproteins. Meanwhile, mesenteric lymph contained an array of proteins that differentiated it from the plasma. The most differentially expressed proteins in mesenteric lymph were gamma-fibrinogen, protease inhibitors, and proteins related to lipid transport/metabolism. The study presents a detailed description of mesenteric lymph proteomes of a common experimental animal in physiological status using a common proteomic approach. These results provide the basis for future research.