Potential testicular aging biomarkers identified in seminal plasma byproteomic analysis

Objective: This research aims to identify biomarkers for the early detection of testicular aging by comparing protein expression levels in seminal plasma from young and older individuals. Methods: Seminal plasma samples from five young and five older men were analyzed using Data Independent Acquisition (DIA) proteomics to identify proteins with differential expression. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were applied to these proteins. Further validation of selected proteins was conducted in new samples of seminal plasma and serum using enzyme-linked immunosorbent assay (ELISA). Results: Using the DIA method, 73 proteins with altered expression levels were detected in seminal plasma—46 exhibited increased expression, while 27 showed decreased expression. GO and KEGG analyses linked these proteins to lipid metabolism, inflammation, and cellular aging processes. ELISA tests confirmed that the proteins GNA13, SAA4, and CYCS were prominently expressed in older seminal plasma samples. Serum analysis using ELISA indicated consistent levels of SAA4 and CYCS compared to seminal plasma but revealed a delayed expression of GNA13. Conclusion: The elevated levels of GNA13 in seminal plasma, which are observed before its detection in serum, correlate with the aging process. This indicates that GNA13 could serve as a promising early indicator for diagnosing testicular aging.