Valentim-Coelho, CristinaSaraiva, JoanaOsório, HugoAntunes, MaríliaVaz, FátimaNeves, SofiaPinto, PaulaBárbara, CristinaPenque, Deborah2026-01-202026-01-202025-03-04Biochim Biophys Acta Mol Basis Dis. 2025 Jun;1871(5):167767. doi: 10.1016/j.bbadis.2025.167767. Epub 2025 Mar 40925-4439http://hdl.handle.net/10400.18/10723Obstructive Sleep Apnea (OSA) is characterized by recurrent-episodes of apneas/hypopneas during sleep, leading to recurrent intermittent-hypoxia and sleep fragmentation. Non-treated OSA can result in cardiometabolic diseases. In this study, we applied a shotgun-proteomics strategy to deeper investigate the red blood cell-(RBC) homeostasis regulation in the context of OSA-severity and their response to six months of positive airway pressure (PAP)-treatment. RBC-samples from patients with Mild/Severe-OSA before/after-PAP treatment and patients as simple-snoring controls were selected. The mass-spectrometry raw-data was analysed by MaxQuant for protein identification/quantification followed by statistical Linear Models-(LM) and Linear Mixed Models-(LMM) to investigate OSA-severity effect and interaction with PAP, respectively. The functional/biological network analysis were performed by DAVID-platform. The results indicated that key-enzymes of the Embden-Meyerhof-Parnas (EMP)-glycolysis and pentose phosphate pathway-(PPP) were differentially changed in Severe-OSA, suggesting that the O2-dependent metabolic flux through EMP and PPP maybe compromised in these cells due to severe intermittent hypoxia/reoxygenation-induced oxidative-stress events in these patients. The Rapoport-Luebering-glycolytic shunt showed a significant downregulation across OSA-severity maybe to increase hemoglobin-O2 affinity to adapt to O2 low availability in the lung, although EMP-glycolysis showed decreased only in Severe-OSA. Proteins of the immunoproteasome were upregulated in Severe-OSA maybe to respond to severe oxidative-stress. In Mild-OSA, proteins related to the ubiquitination/neddylation-(Ub/Ned)-dependent proteasome system were upregulated. After PAP, proteins of Glycolysis and Ub/Ned-dependent proteasome system showed reactivated in Severe-OSA. In Mild-OSA, PAP induced upregulation of immunoproteasome proteins, suggesting that this treatment may increase oxidative-stress in these patients. Once validated these proteins maybe candidate biomarkers for OSA or OSA-therapy response.Highlights: - Glycolysis and PPP main enzymes showed significant alterations in Severe OSA RBCs. - Mild OSA presented significant changes in the Rapoport-Luebering glycolytic shunt. - Immunoproteasome, a cellular homeostasis player, was upregulated in Severe OSA RBCs. - UPS pathway, an ATP-dependent proteasome system, was upregulated in Mild OSA RBCs. - PAP treatment reverted some proteins alterations in OSA RBCs.engGlycolysisObstructive Sleep Apnea (OSA) SeverityPentose Phosphate Pathway (PPP)Positive Airway Pressure (PAP)Proteasome SystemRed Blood CellsGenómica Funcional e Estruturaljournal article10.1016/j.bbadis.2025.1677671879-260X