Proteomic Analysis of Gram-Positive and Gram-Negative Bacterial Infections in Peritoneal Dialysis-Associated Peritonitis

Background: To identify potential biomarkers in peritoneal dialysis effluent (PDE) of patients with Gram-positive (G+) or Gram-negative (G−) bacterial infections in peritoneal dialysis-associated peritonitis (PDAP) and explore diagnostic/therapeutic targets. Methods: PDE samples from 25 PDAP patients (G+:13, G−:12) and 20 non-PDAP controls (Feb 2023–Apr 2024, Ningbo Second Hospital) were analyzed. Proteins were extracted and quantified via LC-MS/MS with data-independent acquisition (DIA). Differentially expressed proteins (DEPs, FC>2 or <0.67, P<0.05) were annotated using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Weighted gene co-expression network analysis (WGCNA) identified key modules linked to G+/G− infections. Results: 1.G+ vs. Controls: 803 DEPs (544↑, 259↓) were enriched in extracellular processes (cell regulation, stimulus response) and pathways (focal adhesion, leukocyte migration). Top upregulated: MMP9, SERPINE1, LTF, ELANE, S100P. 2.G− vs. Controls: 901 DEPs (567↑, 334↓) were linked to vesicle/extracellular structures and pathways (tight junctions, neutrophil extracellular traps). Top upregulated: MMP9, LTF, CAMP, PRTN3, ELANE. 3.G+ vs. G−: Top upregulated DEPs (GHRL, RARRES2, PRB4, MGP, ITLN1) and downregulated DEPs (CAMP, RETN, OLFM4, LTF, NKX2-5). 4.WGCNA revealed 9 co-expression modules: Blue/Black/Turquoise: Correlated with hemoglobin, sodium, urea nitrogen. Red/Pink: Linked to urea nitrogen, dialysis adequacy, creatinine clearance. Yellow: Associated with calcium levels. Gray: Correlated with CRP. Conclusion: GHRL, RARRES2, PRB4, MGP, ITLN1, CAMP, RETN, OLFM4, LTF, and NKX2-5 may serve as potential biomarkers for distinguishing G+/G− PDAP (requiring PRM validation). Clinical factors (hemoglobin, urea nitrogen, dialysis adequacy, creatinine clearance, electrolytes) likely influence infection specificity. Funding: Government Support – Non-U.S.