mariovitali
Senior Member (Voting Rights)
Post-translational modifications within fibrinaloid microclot complexes distinguish Pre-COVID-19 Postural Orthostatic Tachycardia Syndrome (POTS), Long COVID, and Long COVID-POTS and reveal disease-specific molecular pathways
Background: Pre-COVID-19 Postural orthostatic tachycardia syndrome (PC-POTS), Long COVID, and their overlap (LCPOTS) are chronic post-viral conditions marked by debilitating symptoms despite frequently normal routine laboratory results.We previously identified insoluble fibrinaloid microclot complexes (FMCs) in Long COVID. It is not known whether FMCsare also present in PC-POTS, or whether post-translational modifications (PTMs) within FMC-entrapped proteins contributeto disease mechanisms.
Methods: Platelet-poor plasma from healthy controls, PC-POTS patients (collected prior to the COVID-19 pandemic), Long COVID (without POTS) and LC-POTS patients underwent fluorescence imaging flow cytometry toquantify FMCs. Proteomic analyses were performed on insoluble protein fractions using a double trypsin digestion strategy anddata-independent liquid chromatography-tandem mass spectrometry (LC-MS/MS). Differential protein abundance, PTMs, andamyloidogenicity were compared across groups.
Results: Measured with imaging flowcytometry in objects/mL, higher levels of FMCs were present in disease groups compared to controls, although not statistically significant. Statistically significant differencespotentially lay within FMC sizes and composition. Furthermore, despite only a few dysregulated proteins, FMC proteomicsrevealed extensive and disease-specific peptides with PTM dysregulation across coagulation, immune, and metabolic pathways. Long COVID displayed FMCs with PTMs of coagulation proteins including prominent advanced glycation end-products (AGE)-and oxidation-based modifications of fibrinogen subunits, particularly fibrinogen subunit A (FIBA), resembling diabetic glycationprofiles. FMCs in PC-POTS showed fewer fibrinogen PTMs but markedly increased modifications in metabolic proteins, includingoxidised apoA1 and apoB, and immune patterns with complement-related proteins (C3, C4A/B, IC1), immunoglobulin G1 (IGG1)and alpha 2 macroglobulin (A2MG). LC-POTS shared coagulation pathology with Long COVID and immune pathology withPC-POTS. Many dysregulated peptides were determined by in silco methods to be highly amyloidogenic, consistent with FMCsas β-sheet-rich aggregates. Protein-level differences were minimal compared with PTM changes.
Conclusions : This study provides the first evidence that post-translational modifications (PTMs) within fibrinaloid microclots complexes (FMCs) uniquely distinguish pre-COVID-19 POTS, Long COVID, and Long COVID-POTS. Because PC-POTS samples were collected before SARS-CoV-2, their PTM patterns reflect intrinsic disease biology, allowing a clear separation from Long COVID-related changes.
PTM profiling revealed pro-coagulant fibrinogen modifications in Long COVID and LC-POTS, metabolic-oxidative disruptions in Long COVID and PC-POTS, and immune dysregulation in PC-POTS and LC-POTS. None of these is detectable with routine assays, and all are independent of protein abundance. The consistent presence of amyloidogenic peptides suggests a contribution to microvascular dysfunction. These findings define disease-specific PTM landscapes and support new diagnostic and therapeutic avenues across autonomic and post-viral disorders.
Link https://www.biorxiv.org/content/10.64898/2025.12.29.696828v1.full.pdf
Background: Pre-COVID-19 Postural orthostatic tachycardia syndrome (PC-POTS), Long COVID, and their overlap (LCPOTS) are chronic post-viral conditions marked by debilitating symptoms despite frequently normal routine laboratory results.We previously identified insoluble fibrinaloid microclot complexes (FMCs) in Long COVID. It is not known whether FMCsare also present in PC-POTS, or whether post-translational modifications (PTMs) within FMC-entrapped proteins contributeto disease mechanisms.
Methods: Platelet-poor plasma from healthy controls, PC-POTS patients (collected prior to the COVID-19 pandemic), Long COVID (without POTS) and LC-POTS patients underwent fluorescence imaging flow cytometry toquantify FMCs. Proteomic analyses were performed on insoluble protein fractions using a double trypsin digestion strategy anddata-independent liquid chromatography-tandem mass spectrometry (LC-MS/MS). Differential protein abundance, PTMs, andamyloidogenicity were compared across groups.
Results: Measured with imaging flowcytometry in objects/mL, higher levels of FMCs were present in disease groups compared to controls, although not statistically significant. Statistically significant differencespotentially lay within FMC sizes and composition. Furthermore, despite only a few dysregulated proteins, FMC proteomicsrevealed extensive and disease-specific peptides with PTM dysregulation across coagulation, immune, and metabolic pathways. Long COVID displayed FMCs with PTMs of coagulation proteins including prominent advanced glycation end-products (AGE)-and oxidation-based modifications of fibrinogen subunits, particularly fibrinogen subunit A (FIBA), resembling diabetic glycationprofiles. FMCs in PC-POTS showed fewer fibrinogen PTMs but markedly increased modifications in metabolic proteins, includingoxidised apoA1 and apoB, and immune patterns with complement-related proteins (C3, C4A/B, IC1), immunoglobulin G1 (IGG1)and alpha 2 macroglobulin (A2MG). LC-POTS shared coagulation pathology with Long COVID and immune pathology withPC-POTS. Many dysregulated peptides were determined by in silco methods to be highly amyloidogenic, consistent with FMCsas β-sheet-rich aggregates. Protein-level differences were minimal compared with PTM changes.
Conclusions : This study provides the first evidence that post-translational modifications (PTMs) within fibrinaloid microclots complexes (FMCs) uniquely distinguish pre-COVID-19 POTS, Long COVID, and Long COVID-POTS. Because PC-POTS samples were collected before SARS-CoV-2, their PTM patterns reflect intrinsic disease biology, allowing a clear separation from Long COVID-related changes.
PTM profiling revealed pro-coagulant fibrinogen modifications in Long COVID and LC-POTS, metabolic-oxidative disruptions in Long COVID and PC-POTS, and immune dysregulation in PC-POTS and LC-POTS. None of these is detectable with routine assays, and all are independent of protein abundance. The consistent presence of amyloidogenic peptides suggests a contribution to microvascular dysfunction. These findings define disease-specific PTM landscapes and support new diagnostic and therapeutic avenues across autonomic and post-viral disorders.
Link https://www.biorxiv.org/content/10.64898/2025.12.29.696828v1.full.pdf
Last edited by a moderator: