Assembly of alternative prothrombinase by extracellular histones initiates and disseminates intravascular coagulation.

Thrombin generation is pivotal to both physiological blood clot formation and pathological development of disseminated intravascular coagulation (DIC). In critical illness, extensive cell damage can release histones into the circulation, which can increase thrombin generation and cause DIC, but the molecular mechanism is not clear. Typically, thrombin is generated by the prothrombinase complex, comprising activated factor X (FXa), activated cofactor V (FVa), and phospholipids to cleave prothrombin in the presence of calcium. In this study, we found that in the presence of extracellular histones, an alternative prothrombinase could form without FVa and phospholipids. Histones directly bind to prothrombin fragment 1 (F1) and fragment 2 (F2) specifically to facilitate FXa cleavage of prothrombin to release active thrombin, unlike FVa, which requires phospholipid surfaces to anchor the classical prothrombinase complex. In vivo, histone infusion into mice induced DIC, which was significantly abrogated when prothrombin F1 + F2 were infused prior to histones, to act as decoy. In a cohort of intensive care unit patients with sepsis (n = 144), circulating histone levels were significantly elevated in patients with DIC. These data suggest that histone-induced alternative prothrombinase without phospholipid anchorage may disseminate intravascular coagulation and reveal a new molecular mechanism of thrombin generation and DIC development. In addition, histones significantly reduced the requirement for FXa in the coagulation cascade to enable clot formation in factor VIII (FVIII)- and FIX-deficient plasma, as well as in FVIII-deficient mice. In summary, this study highlights a novel mechanism in coagulation with therapeutic potential in both targeting systemic coagulation activation and correcting coagulation factor deficiency.

Cross Talk Pathways Between Coagulation and Inflammation.

Anatomic pathology studies performed over 150 years ago revealed that excessive activation of coagulation occurs in the setting of inflammation. However, it has taken over a century since these seminal observations were made to delineate the molecular mechanisms by which these systems interact and the extent to which they participate in the pathogenesis of multiple diseases. There is, in fact, extensive cross talk between coagulation and inflammation, whereby activation of one system may amplify activation of the other, a situation that, if unopposed, may result in tissue damage or even multiorgan failure. Characterizing the common triggers and pathways are key for the strategic design of effective therapeutic interventions. In this review, we highlight some of the key molecular interactions, some of which are already showing promise as therapeutic targets for inflammatory and thrombotic disorders.

Plasmin(ogen) at the Nexus of Fibrinolysis, Inflammation, and Complement.

The diverse mechanisms by which the plasmin(ogen) system is involved in human physiology and pathology are constantly being delineated. For many years, the plasmin(ogen) system was chiefly known as the system responsible for vascular fibrinolysis. Although this is an important function of the plasmin(ogen) system, we now recognize that plasmin(ogen) is critically important as a mediator of inflammation and the innate immune system, which impacts upon a diverse set of mechanisms underlying the pathologies of many diseases. The current review focuses on recent developments in plasmin(ogen) system activation and regulation and how dysregulation of this finely tuned system may contribute to inflammatory disease (atherosclerosis), impaired wound healing, and infection.

Procoagulant activity in stored units of red blood cells.

The procoagulant activity (PA) of stored units of red blood cells (RBC) increases over time, which is related to the expression/exposure of tissue factor (TF). However, there is a discrepancy between the TF measured and changes in PA observed, suggesting that other blood components contribute to this activity. Our goal was to evaluate changes in PA of stored RBCs and to determine possible contributors to it. RBC units from 4 healthy donors were prepared and stored at 4 °C. On selected days, RBC aliquots were reconstituted with autologous plasma and tested in the thromboelastography assay. Corresponding supernatants were tested in a clotting assay. For all donors, the clotting time (CT) of reconstituted RBC units decreased from ∼3000-4000s on day 1 to ∼1000-1600s on day 30, with the most dramatic changes occurring between days 1 and 5. Anti-TF antibody slightly prolonged the CT. The concentration of TF did not change significantly over time and was within the range of 0.3-2.3 pM. Bovine lactadherin (LTD) prolonged the CT of the RBC (by 2.4-3.4-fold in days 3-5 and by 1.3-1.8-fold at day 30). Anti-TF antibody together with LTD had a cumulative effect on the CT prolongation. CT of supernatants responded to both anti-TF and anti-FXIa antibodies. Three contributors to the PA of stored RBC were identified, i.e. FXIa in solution and phosphatidylserine and TF exposed on blood cells and microparticles. Failure of LTD and antibodies to completely eliminate PA suggests that other components of blood could contribute to it.

Polyphosphate suppresses complement via the terminal pathway.

Polyphosphate, synthesized by all cells, is a linear polymer of inorganic phosphate. When released into the circulation, it exerts prothrombotic and proinflammatory activities by modulating steps in the coagulation cascade. We examined the role of polyphosphate in regulating the evolutionarily related proteolytic cascade complement. In erythrocyte lysis assays, polyphosphate comprising more than 1000 phosphate units suppressed total hemolytic activity with a concentration to reduce maximal lysis to 50% that was 10-fold lower than with monophosphate. In the ion- and enzyme-independent terminal pathway complement assay, polyphosphate suppressed complement in a concentration- and size-dependent manner. Phosphatase-treated polyphosphate lost its ability to suppress complement, confirming that polymer integrity is required. Sequential addition of polyphosphate to the terminal pathway assay showed that polyphosphate interferes with complement only when added before formation of the C5b-7 complex. Physicochemical analyses using native gels, gel filtration, and differential scanning fluorimetry revealed that polyphosphate binds to and destabilizes C5b,6, thereby reducing the capacity of the membrane attack complex to bind to and lyse the target cell. In summary, we have added another function to polyphosphate in blood, demonstrating that it dampens the innate immune response by suppressing complement. These findings further establish the complex relationship between coagulation and innate immunity.

Hi-Fi SELEX: A High-Fidelity Digital-PCR Based Therapeutic Aptamer Discovery Platform.

Current technologies for aptamer discovery typically leverage the systematic evolution of ligands by exponential enrichment (SELEX) concept by recursively panning semi-combinatorial ssDNA or RNA libraries against a molecular target. The expectation is that this iterative selection process will be sufficiently stringent to identify a candidate pool of specific high-affinity aptamers. However, failure of this process to yield promising aptamers is common, due in part to (i) limitations in library designs, (ii) retention of non-specific aptamers during screening rounds, (iii) excessive accumulation of amplification artifacts, and (iv) the use of screening criteria (binding affinity) that does not reflect therapeutic activity. We report a new selection platform, High-Fidelity (Hi-Fi) SELEX, that introduces fixed-region blocking elements to safeguard the functional diversity of the library. The chemistry of the target-display surface and the composition of the equilibration solvent are engineered to strongly inhibit non-specific retention of aptamers. Partition efficiencies approaching 10(6) are thereby realized. Retained members are amplified in Hi-Fi SELEX by digital PCR in a manner that ensures both elimination of amplification artifacts and stoichiometric conversion of amplicons into the single-stranded library required for the next selection round. Improvements to aptamer selections are first demonstrated using human α-thrombin as the target. Three clinical targets (human factors IXa, X, and D) are then subjected to Hi-Fi SELEX. For each, rapid enrichment of ssDNA aptamers offering an order-nM mean equilibrium dissociation constant (Kd) is achieved within three selection rounds, as quantified by a new label-free qPCR assay reported here. Therapeutic candidates against factor D are identified.

Solulin increases clot stability in whole blood from humans and dogs with hemophilia.

Solulin is a soluble form of thrombomodulin that is resistant to proteolysis and oxidation. It has been shown to increase the clot lysis time in factor VIII (fVIII)-deficient plasma by an activated thrombin-activatable fibrinolysis inhibitor (TAFIa)-dependent mechanism. In the present study, blood was drawn from humans and dogs with hemophilia, and thromboelastography was used to measure tissue factor-initiated fibrin formation and tissue-plasminogen activator-induced fibrinolysis. The kinetics of TAFI and protein C activation by the thrombin-Solulin complex were determined to describe the relative extent of anticoagulation and antifibrinolysis. In severe hemophilia A, clot stability increased by > 4-fold in the presence of Solulin while minimally affecting clot lysis time. Patients receiving fVIII/fIX prophylaxis showed a similar trend of increased clot stability in the presence of Solulin. The catalytic efficiencies of TAFI and protein C activation by the thrombin-Solulin complex were determined to be 1.53 and 0.02/µM/s, respectively, explaining its preference for antifibrinolysis over anticoagulation at low concentrations. Finally, hemophilic dogs given Solulin had improved clot strength in thromboelastography assays. In conclusion, the antifibrinolytic properties of Solulin are exhibited in hemophilic human (in vitro) and dog (in vivo/ex vivo) blood at low concentrations. Our findings suggest the therapeutic utility of Solulin at a range of very low doses.

An in-vitro assessment of tranexamic acid as an adjunct to rFVIII or rFVIIa treatment in haemophilia A.

Haemophilia is characterised by defective thrombin generation, reduced clot stability and spontaneous bleeding. Treatment with factor VIII (FVIII) concentrate or bypassing agents (e.g. recombinant factor VIIa (rFVIIa)) is generally effective. Occasionally, haemostasis is not achieved, which may reflect a failure of factor concentrate to normalise clot stability. Tranexamic acid (TXA) is often used to aid haemostasis in surgery (e.g. joint replacements and dental procedures). Used routinely as an adjunct, it may enhance clot stability and allow effective, reliable, and cost-effective treatment at lower doses of factor concentrate. This study hypothesised that clot stabilising adjunct TXA is required in addition to factor substitution to normalise clot stability in whole blood from patients with severe haemophilia A. The in vitro effect of varying concentrations of recombinant FVIII or recombinant FVIIa and adjunct TXA on whole blood clot stability was measured by thromboelastometry. Coagulation was triggered by tissue factor and clots were challenged with tissue plasminogen activator. The area under the elasticity curve was the primary endpoint. High concentrations of FVIII and rFVIIa increased clot stability to levels that were not significantly different from controls (Mean ± SD: control 112,694 ± 84,115; FVIII 78,662 ± 74,126; rFVIIa 95,918 ± 88,492). However, the response was highly variable between individuals and demonstrates why some patients show clinical resistance to treatment. Addition of TXA resulted in normalised clot stability in all individuals, even when combined with the lowest doses of factor concentrate. The results support the concept that a more efficient, reliable and cost effective treatment may be obtained if TXA is combined with factor concentrates to treat individuals with haemophilia.

Differences in wild-type- and R338L-tenase complex formation are at the root of R338L-factor IX assay discrepancies.

Adeno-associated virus (AAV) gene therapy has the potential to functionally cure hemophilia B by restoring factor (F)IX concentrations into the normal range. Next-generation AAV therapies express a naturally occurring gain-of-function FIX variant, FIX-Padua (R338L-FIX), that increases FIX activity (FIX:C) by approximately eightfold compared with wild-type FIX (FIX-WT). Previous studies have shown that R338L-FIX activity varies dramatically across different clinical FIX:C assays, which complicates the monitoring and management of patients. To better understand mechanisms that contribute to R338L-FIX assay discrepancies, we characterized the performance of R338L-FIX in 13 1-stage clotting assays (OSAs) and 2 chromogenic substrate assays (CSAs) in a global field study. This study produced the largest R338L-FIX assay dataset to date and confirmed that clinical FIX:C assay results vary over threefold. Both phospholipid and activating reagents play a role in OSA discrepancies. CSA generated the most divergent FIX:C results. Manipulation of FIX:C CSA kits demonstrated that specific activity gains for R338L-FIX were most profound at lower FIX:C concentrations and that these effects were enhanced during the early phases of FXa generation. Supplementing FX into CSA had the effect of dampening FIX-WT activity relative to R338L-FIX activity, suggesting that FX impairs WT tenase formation to a greater extent than R338L-FIX tenase. Our data describe the scale of R338L-FIX assay discrepancies and provide insights into the causative mechanisms that will help establish best practices for the measurement of R338L-FIX activity in patients after gene therapy.

Nebulized Recombinant Tissue Plasminogen Activator (rt-PA) for Acute COVID-19-Induced Respiratory Failure: An Exploratory Proof-of-Concept Trial.

Acute lung injury in COVID-19 results in diffuse alveolar damage with disruption of the alveolar-capillary barrier, coagulation activation, alveolar fibrin deposition and pulmonary capillary thrombi. Nebulized recombinant tissue plasminogen activator (rt-PA) has the potential to facilitate localized thrombolysis in the alveolar compartment and improve oxygenation. In this proof-of-concept safety study, adults with COVID-19-induced respiratory failure and a <300 mmHg PaO2/FiO2 (P/F) ratio requiring invasive mechanical ventilation (IMV) or non-invasive respiratory support (NIRS) received nebulized rt-PA in two cohorts (C1 and C2), alongside standard of care, between 23 April-30 July 2020 and 21 January-19 February 2021, respectively. Matched historical controls (MHC; n = 18) were used in C1 to explore efficacy. Safety co-primary endpoints were treatment-related bleeds and <1.0-1.5 g/L fibrinogen reduction. A variable dosing strategy with clinical efficacy endpoint and minimal safety concerns was determined in C1 for use in C2; patients were stratified by ventilation type to receive 40-60 mg rt-PA daily for ≤14 days. Nine patients in C1 (IMV, 6/9; NIRS, 3/9) and 26 in C2 (IMV, 12/26; NIRS, 14/26) received nebulized rt-PA for a mean (SD) of 6.7 (4.6) and 9.1(4.6) days, respectively. Four bleeds (one severe, three mild) in three patients were considered treatment related. There were no significant fibrinogen reductions. Greater improvements in mean P/F ratio from baseline to study end were observed in C1 compared with MHC (C1; 154 to 299 vs. MHC; 154 to 212). In C2, there was no difference in the baseline P/F ratio of NIRS and IMV patients. However, a larger improvement in the P/F ratio occurred in NIRS patients (NIRS; 126 to 240 vs. IMV; 120 to 188) and fewer treatment days were required (NIRS; 7.86 vs. IMV; 10.5). Nebulized rt-PA appears to be well-tolerated, with a trend towards improved oxygenation, particularly in the NIRS group. Randomized clinical trials are required to demonstrate the clinical effect significance and magnitude.

Kinetics of activated thrombin-activatable fibrinolysis inhibitor (TAFIa)-catalyzed cleavage of C-terminal lysine residues of fibrin degradation products and removal of plasminogen-binding sites.

Partial digestion of fibrin by plasmin exposes C-terminal lysine residues, which comprise new binding sites for both plasminogen and tissue-type plasminogen activator (tPA). This binding increases the catalytic efficiency of plasminogen activation by 3000-fold compared with tPA alone. The activated thrombin-activatable fibrinolysis inhibitor (TAFIa) attenuates fibrinolysis by removing these residues, which causes a 97% reduction in tPA catalytic efficiency. The aim of this study was to determine the kinetics of TAFIa-catalyzed lysine cleavage from fibrin degradation products and the kinetics of loss of plasminogen-binding sites. We show that the k(cat) and K(m) of Glu(1)-plasminogen (Glu-Pg)-binding site removal are 2.34 s(-1) and 142.6 nm, respectively, implying a catalytic efficiency of 16.21 µm(-1) s(-1). The corresponding values of Lys(77)/Lys(78)-plasminogen (Lys-Pg)-binding site removal are 0.89 s(-1) and 96 nm implying a catalytic efficiency of 9.23 µm(-1) s(-1). These catalytic efficiencies of plasminogen-binding site removal by TAFIa are the highest of any TAFIa-catalyzed reaction with a biological substrate reported to date and suggest that plasmin-modified fibrin is a primary physiological substrate for TAFIa. We also show that the catalytic efficiency of cleavage of all C-terminal lysine residues, whether they are involved in plasminogen binding or not, is 1.10 µm(-1) s(-1). Interestingly, this value increases to 3.85 µm(-1) s(-1) in the presence of Glu-Pg. These changes are due to a decrease in K(m). This suggests that an interaction between TAFIa and plasminogen comprises a component of the reaction mechanism, the plausibility of which was established by showing that TAFIa binds both Glu-Pg and Lys-Pg.

Fibrinogen as a hemostatic agent.

Coagulation factor I (fibrinogen) plays an essential role in the hemostatic system by bridging activated platelets and being the key substrate for thrombin in establishing a consolidating fibrin network. Fibrinogen is synthesized in the liver and the plasma concentration is 1 to 5-4.0 g/L. During recent 10 years, fibrinogen has been recognized to play an important role in controlling hemorrhage. Dilutional coagulopathy induced by colloid plasma expanders is characterized by fibrinogen deficiency and dysfunctional fibrin polymerization. Trauma and use of extracorporeal circulation is also known to reduce levels of fibrinogen. A series of laboratory experiments and experimental animal studies have suggested fibrinogen as a potent hemostatic agent. These data are supported by retrospective surveys as well as a series of prospective proof of principal clinical trials. This article provides a description of the biochemistry and mechanisms of fibrinogen as well as the etiology for developing fibrinogen deficiency. Furthermore, it summarizes laboratory and experimental data on the role of fibrinogen in dilutional coagulopathy and addresses laboratory monitoring issues. Finally, it lists retrospective and prospective studies, which have been designed to assess the clinical efficacy and safety of hemostatic intervention with fibrinogen concentrate.

Impaired platelet-dependent thrombin generation associated with thrombocytopenia is improved by prothrombin complex concentrates in vitro.

BACKGROUND: Impaired thrombin generation (TG) in patients with acquired coagulopathy, is due to low coagulation factors and thrombocytopenia. The latter is typically treated with platelet transfusions and the former with plasma and occasionally with prothrombin complex concentrates (PCCs). We hypothesized that manipulating the concentrations of coagulation factors might result in restoration of platelet-dependent TG over and above that of simple replacement therapy. OBJECTIVE: To investigate the influence of PCCs on impaired TG secondary to thrombocytopenia. METHODS: TG was evaluated by thrombin generation assay using a thrombocytopenia model in which normal plasma samples with varying platelet counts (20-300 × 109/L) were spiked with PCCs (25%-150% increase in plasma PCC levels). RESULTS: PCCs and platelets significantly increased TG in a dose-dependent manner in vitro. Two-way repeated measures of analysis of variance showed variance in peak height, area under the curve, time to peak, and velocity. This variance explained, respectively, by levels of PCC was 47, 59, 25 and 53%; by platelet count was 45, 28, 44, and 14%; by the combination was 80, 67, 70, and 62% variance; and a combination with additional interaction was 91, 84, 76, and 68%. TG at a platelet count 40 × 109/L with an approximate 25% increase in PCC concentration was similar to TG at 150 × 109/L. Similarly, patient samples spiked ex vivo with PCCs also showed highly significant improvements in TG. CONCLUSIONS: Impaired TG of thrombocytopenia is improved by PCCs, supporting the need for additional studies in complex coagulopathies characterized by mild to moderate thrombocytopenia and abnormal coagulation.

Increased production and secretion of HGF alpha-chain and an antagonistic HGF fragment in a human breast cancer progression model.

Invasive human breast carcinomas frequently coexpress increased hepatocyte growth factor (HGF) and its receptor Met, suggesting that establishment of an autocrine HGF loop is important in malignant disease. This study examines the expression patterns of HGF and Met activation during tumorigenesis and metastasis using a MCF10A-based model of Ha-Ras-induced human breast cancer progression. Deregulation of cadherin-based cell-cell adhesions, decreased expression of cytokeratins 8/18 and increased activity of matrix metalloproteinases such as MMP-2 occurs in premalignant and malignant (metastatic) cell lines compared to the parental nonmalignant cell line. Compared to the benign parent cell line, premalignant and malignant cell lines exhibit increased secretion of full length HGF alpha-chain and elevated Met tyrosine phosphorylation in complete medium. Interestingly, the premalignant and malignant cells also secrete a approximately 55 kDa HGF fragment. Epitope mapping of the approximately 55 kDa HGF fragment supports the presence of the N-terminal domain of the HGF alpha-chain with a truncation in the C-terminal domain. The approximately 55 kDa HGF fragment shows mobility in SDS-PAGE faster than HGF alpha-chain, but slightly slower than NK4, a previously established full antagonist of HGF. The separated approximately 55 kDa HGF fragment binds to animmobilized Met-IgG fusion protein, and inhibits both HGF/Met-IgG binding and HGF-induced Met-tyrosine phosphorylation. These results are the first demonstration of an antagonistic approximately 55 kDa HGF fragment secreted during breast carcinoma progression, which may have a negative regulatory effect on HGF signaling in premalignant breast epithelial cells.

Examining coagulation-complement crosstalk: complement activation and thrombosis.

The coagulation and complement systems are ancestrally related enzymatic cascades of the blood. Although their primary purposes have diverged over the past few hundred million years, they remain inextricably connected. Both complement and coagulation systems limit infection by pathogens through innate immune mechanisms. Recently, it has been shown that hyperactive complement (in particular, elevated C5a/C5b-9) is involved in the pathogenesis (including thrombosis) of diseases such as paroxysmal nocturnal hemoglobinuria, atypical haemolytic uremic syndrome, antiphospholipid syndrome and bacteremia. Although these diseases together account for many thrombosis cases, there are many more where complement activation is not considered a causative factor leading to thrombosis. To better understand what role complement may play in the pathogenesis of thrombosis a better understanding of the mechanisms that cause over-active complement in thrombotic disease is required.

Complement Activation in Arterial and Venous Thrombosis is Mediated by Plasmin.

Thrombus formation leading to vaso-occlusive events is a major cause of death, and involves complex interactions between coagulation, fibrinolytic and innate immune systems. Leukocyte recruitment is a key step, mediated partly by chemotactic complement activation factors C3a and C5a. However, mechanisms mediating C3a/C5a generation during thrombosis have not been studied. In a murine venous thrombosis model, levels of thrombin-antithrombin complexes poorly correlated with C3a and C5a, excluding a central role for thrombin in C3a/C5a production. However, clot weight strongly correlated with C5a, suggesting processes triggered during thrombosis promote C5a generation. Since thrombosis elicits fibrinolysis, we hypothesized that plasmin activates C5 during thrombosis. In vitro, the catalytic efficiency of plasmin-mediated C5a generation greatly exceeded that of thrombin or factor Xa, but was similar to the recognized complement C5 convertases. Plasmin-activated C5 yielded a functional membrane attack complex (MAC). In an arterial thrombosis model, plasminogen activator administration increased C5a levels. Overall, these findings suggest plasmin bridges thrombosis and the immune response by liberating C5a and inducing MAC assembly. These new insights may lead to the development of strategies to limit thrombus formation and/or enhance resolution.

Modulation of complement activation and amplification on nanoparticle surfaces by glycopolymer conformation and chemistry.

The complement system plays an integral part of a host's innate immunity, and its activation is highly dependent on the chemistry and structure of a "foreign" target surface. We determined that the conformational state of glycopolymer chains, defined by the grafting density (chains/nm(2)), on the nanoparticle (NP) surface acts as a "molecular switch" for complement activation and amplification, and the protein corona on the NP surface dictates this process. A grafting density threshold was determined, below which minimal complement activation was observed and above which substantial complement activation was detected. The glycopolymer-grafted NPs activated complement via the alternative pathway. The chemical structure of pendent sugar units on the grafted polymer was also an important determinant for complement activation. NPs grafted with glucose-containing polymer activated complement at a lower grafting density compared to NPs grafted with galactose-containing polymer. Analysis of complement activation products C3a and SC5b-9 followed a similar pattern. Complement activation on the NP surface was independent of particle size or concentration for a given conformational state of grafted polymer. To gain insight into a putative surface-dependent mechanism of complement activation, we determined the nature of adsorbed protein corona on various NPs through quantitative mass spectrometry. Elevated levels of two pro-complement proteins, factors B and C3, present on the NP surface grafted with glycopolymer chains at high grafting density compared to low grafting density surface, may be responsible for its complement activity. Galactose polymer modified NPs adsorbed more of the negative regulator of complement, factor H, than the glucose surface, providing an explanation for its lower level of complement activation.

Modulation of inflammatory and hemostatic markers in obstructive sleep apnea patients treated with mandibular advancement splints: a parallel, controlled trial.

STUDY OBJECTIVE: Obstructive sleep apnea (OSA) is associated with systemic inflammation and a hypercoagulable state. The current study aim was to investigate whether mandibular advancement splint (MAS) therapy affects inflammatory and hemostatic parameters in patients with mild-to-moderate OSA. METHODS: Twenty-two patients with mild-to-moderate OSA and 16 control subjects were studied. OSA subjects were treated with a titratable MAS for 6 months. Baseline plasma C-reactive protein, interleukin-1ß, interleukin-10, interleukin-6, P-selectin, fibrinogen, D-dimer, plasminogen activator inhibitor-1 (PAI-1), thrombin-antithrombin complex, activated thrombin-activatable fibrinolysis inhibitor (TAFIa), 6-keto-PGF1α, glucose, and fibrin clot lysis time (CLT) were measured in all subjects. After 3 months of MAS therapy, measurements were repeated for the 22 patients, and after 6 months all measurements were repeated for all study subjects. RESULTS: MAS treatment reduced significantly AHI at 3 months (24 vs 13.1/h) and further improved it at 6 months (13.1 vs 7.05/h). Compared with controls, OSA subjects had a significant higher baseline mean levels of fibrinogen, TAFIa, 6-keto-PGF1α, and glucose. MAS treatment significantly improved levels of IL-1ß, D-dimer, TAFIa, and CLT. Despite residual apneas, MAS treatment group presented similar measured homeostatic and inflammatory levels to controls except for glucose. CONCLUSION: Treatment with MAS in mild-to-moderate OSA subjects improves the inflammatory profile and homeostatic markers. CITATION: Nizankowska-Jedrzejczyk A; Almeida FR; Lowe AA; Kania A; Nastalek P; Mejza F; Foley JH; Nizankowska-Mogilnicka E; Undas A. Modulation of inflammatory and hemostatic markers in obstructive sleep apnea patients treated with mandibular advancement splints: a parallel, controlled trial.