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Stage-dependent proteomic alterations in aqueous humor of diabetic retinopathy patients based on data-independent acquisition and parallel reaction monitoring.

BACKGROUND: Diabetic retinopathy (DR), a microvascular complication of diabetes mellitus (DM), represents the predominant cause of preventable vision loss in working-age populations globally. While the pathophysiological mechanisms underlying DR progression remain incompletely understood, our study employs comprehensive proteomic profiling of aqueous humor (AH) to identify stage-specific biomarkers and therapeutic targets in type 2 diabetes mellitus (T2DM) patients across DR progression. METHODS: Utilizing data-independent acquisition (DIA) mass spectrometry, we quantified AH proteomes in a discovery cohort comprising 24 subjects: 18 T2DM patients stratified by DR severity [6 non-DR, 6 non-proliferative DR (NPDR), 6 proliferative DR (PDR)] and 6 cataract controls without diabetes (non-DM). Validation cohort analysis (including 10 AH samples in each group) was performed using parallel reaction monitoring (PRM) strategy for verification of target proteins. Comprehensive bioinformatics analyses included gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis, protein-protein interaction (PPI) network construction, receiver operating characteristic (ROC) curve analysis, and ConnectivityMap (Cmap)-based drug prediction. RESULTS: Proteomic profiling identified 739 quantifiable AH proteins (62% extracellular) with clear separation among the four clinical stages in the discovery cohort. GSEA uncovered altered expression of proteins mainly related to complement and coagulation cascades, folate metabolism, and the selenium micronutrient network in patients with DR. WGCNA-derived protein modules yielded 83 PRM-validated targets, including 5 hub proteins differentiating NPDR from non-DR and 33 hub proteins showed significant upregulation in PDR versus NPDR comparison. Clinical correlation analysis identified F2, FGG, FGB, RBP4, AMBP, VTN, C8A, CPB2, and C2 associated with clinical traits. C6, FAM3C, SPP1, and JCHAIN levels were altered post-anti-VEGF treatment. Pharmacological prediction identified potential therapeutic compounds, including perindopril, triciribine, and XAV-939 for NPDR, and topiramate, triciribine, and vecuronium for PDR. CONCLUSION: This study established a comprehensive AH proteomic signature of DR progression, offering insights into the pathogenesis of DR and highlighting potential biomarkers and novel therapeutic targets.

Humans

Development of a High-Sensitivity Glycoproteomics Approach for Fc-Specific Quantification of IgG Core Fucosylation in Traumatic Brain Injury.

Traumatic brain injury (TBI) triggers complex neuroinflammatory cascades that involve sustained immune activation and dysregulated antibody effector functions. Immunoglobulin G (IgG) Fc N-glycosylation, particularly core fucosylation, critically modulates immune signaling through altered Fcγ receptor (FcγR) interactions; however, its role in TBI remains unexplored. Here, we developed a high-sensitivity, mass spectrometry-based glycoproteomics method for the systematic analysis of IgG Fc core fucosylation dynamics following TBI. The approach integrates Fc-specific enzymatic truncation with GlycINATOR (EndoS2) and tryptic digestion, followed by high-resolution LC-MS/MS profiling, enabling confident identification of truncated Fc glycopeptides. Furthermore, a targeted parallel reaction monitoring (PRM) strategy allowed direct quantification of core fucosylated and afucosylated glycopeptides from 10 μg of crude serum protein, eliminating the need for IgG purification. Our results reveal time-dependent and subclass-specific remodeling of IgG Fc fucosylation postinjury, characterized by an overall reduction in fucosylated species and a relative increase in afucosylation. Collectively, this study establishes a scalable analytical platform for Fc-specific glycosylation profiling and identifies IgG core fucosylation as a candidate molecular indicator of immune dysregulation in TBI, providing new insights into post-traumatic immune regulation.

Brain Injuries, Traumatic

High Hcy regulates fluid shear stress pathway activity through histone H3K79 homocysteinylation in hyperhomocysteinemia-related child hypertension.

BACKGROUND: The rise of hypertension in children has been increasingly associated with hyperhomocysteinemia (HHcy), which is recognized as a major risk factor. However, the underlying mechanisms linking homocysteine and hypertension (termed HHYP) are not fully understood. METHODS: This study utilized plasma samples from 27 control children and 27 children with HHYP (aged 8 ~ 16 years) for TMT6-labeled proteomic quantification, identifying significant altered proteins. Bioinformatics analysis revealed pathway alterations. Verification was carried out via parallel reaction monitoring (PRM) and western blot (WB) analyses. Additionally, a rat model of HHYP induced by high methionine diets, and umbilical vein endothelial cell models exposed to high homocysteine (hcy) levels were developed to investigate the molecular underpinnings further. Protein expression changes and epigenetic modifications were assessed using WB, immunohistochemistry (IHC), and ChIP-qPCR techniques. RESULTS: Key findings indicated that 357 proteins and 69 pathways were altered in children with HHYP. Specifically, 12 proteins within the fluid shear stress and atherosclerosis (FSSA) pathway showed differential expression, including the downregulation of TRX1 and GPX1 and the upregulation of ICAM1. The same expression patterns were noted in both the HHYP rat aortic tissues and the high hcy cultured endothelial cells. Moreover, elevated H3K79hcy modification levels were observed alongside epigenetic regulation of genes related to the FSSA pathway. Importantly, folic acid (FA), a medication frequently used in the clinical treatment of HHYP, has been demonstrated to effectively reverse H3K79hcy modifications and restore the disrupted FSSA pathway in both animal models and cell cultures. CONCLUSIONS: The present study suggests that HHcy may contribute to hypertension through the epigenetic dysregulation of the FSSA pathway mediated by H3K79hcy. Furthermore, the pediatric proteomics data gleaned from this study offer new clinical insights into the pathophysiology of HHYP in children.

Hyperhomocysteinemia

optiPRM: A Targeted Immunopeptidomics LC-MS Workflow With Ultra-High Sensitivity for the Detection of Mutation-Derived Tumor Neoepitopes From Limited Input Material.

Personalized cancer immunotherapies such as therapeutic vaccines and adoptive transfer of T cell receptor-transgenic T cells rely on the presentation of tumor-specific peptides by human leukocyte antigen class I molecules to cytotoxic T cells. Such neoepitopes can for example arise from somatic mutations and their identification is crucial for the rational design of new therapeutic interventions. Liquid chromatography mass spectrometry (LC-MS)-based immunopeptidomics is the only method to directly prove actual peptide presentation and we have developed a parameter optimization workflow to tune targeted assays for maximum detection sensitivity on a per peptide basis, termed optiPRM. Optimization of collision energy using optiPRM allows for the improved detection of low abundant peptides that are very hard to detect using standard parameters. Applying this to immunopeptidomics, we detected a neoepitope in a patient-derived xenograft from as little as 2.5 × 106 cells input. Application of the workflow on small patient tumor samples allowed for the detection of five mutation-derived neoepitopes in three patients. One neoepitope was confirmed to be recognized by patient T cells. In conclusion, optiPRM, a targeted MS workflow reaching ultra-high sensitivity by per peptide parameter optimization, makes the identification of actionable neoepitopes possible from sample sizes usually available in the clinic.

Humans