Serum protein profiles suggest a possible link between qi deficiency constitution and Pi-qi-deficiency syndrome of chronic superficial gastritis

Objective: To identify potential serum protein candidates involved in linking the traditional Chinese medicine (TCM)-defined qi deficiency constitution (QDC) to Pi-qi-deficiency syndrome (PQDS) of chronic superficial gastritis (CSG). Methods: Using participants with the TCM-defined balanced constitution as a control population, label-free quantitative proteomics was adopted to identify differentially expressed proteins (DEPs) in serum samples from two case populations: case population 1 (participants with QDC) and case population 2 (patients with PQDS of CSG). The DEPs discovered in both case populations were analyzed to identify common DEPs as potential candidates for proteins involved in the link between QDC and PQDS. Based on Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) and Gene Ontology (GO) enrichment analysis and analysis of protein–protein interaction networks, we evaluated the possible functions of these potential serum candidates. Results: We discovered 24 and 28 proteins that were differentially expressed in case populations 1 and 2, respectively, compared with the control population. Hierarchical clustering analysis showed that the expression profile of DEPs of individuals from the same population clustered well, while those from different populations were segregated. Furthermore, GO analysis revealed the 10 DEPs that were common to both case populations to be mainly associated with negative regulation of cellular metabolic and immune system processes while KEGG analysis indicated these proteins to be associated with complement and coagulation cascades and peroxisome proliferator-activated receptor signaling. Notably, serum levels of C4b-binding protein beta chain, glycosylphosphatidylinositol-specific phospholipase D1 and MS-F1 light chain variable region proteins were notably higher in the two case populations compared with the control, particularly in the case of CSG with PQDS. Conclusion: The results presented here provide new insights into the molecular mechanisms underlying development of PQDS of CSG from QDC, and suggest candidate serum biomarkers for future application in integrative medicine. Keywords: Qi deficiency constitution, Pi-qi-deficiency syndrome, Chronic superficial gastritis, Serum biomarker