Role Of Heparin Research Articles

The Role of Heparin in Postural Orthostatic Tachycardia Syndrome and Other Post-Acute Sequelae of COVID-19.

The therapeutic management and short-term consequences of the coronavirus disease 2019 (COVID-19) are well known. However, COVID-19 post-acute sequelae are less known and represent a public health problem worldwide. Patients with COVID-19 who present post-acute sequelae may display immune dysregulation, a procoagulant state, and persistent microvascular endotheliopathy that could trigger microvascular thrombosis. These elements have also been implicated in the physiopathology of postural orthostatic tachycardia syndrome, a frequent sequela in post-COVID-19 patients. These mechanisms, directly associated with post-acute sequelae, might determine the thrombotic consequences of COVID-19 and the need for early anticoagulation therapy. In this context, heparin has several potential benefits, including immunomodulatory, anticoagulant, antiviral, pro-endothelial, and vascular effects, that could be helpful in the treatment of COVID-19 post-acute sequelae. In this article, we review the evidence surrounding the post-acute sequelae of COVID-19 and the potential benefits of the use of heparin, with a special focus on the treatment of postural orthostatic tachycardia syndrome.

The role of heparin in spike SARS-CoV-2 infection: From a model for heparan sulfates to a starting structure for antivirals

The role of heparin in spike SARS-CoV-2 infection: From a model for heparan sulfates to a starting structure for antivirals

Heparin-collagen I bilayers stimulate FAK/ERK½ signaling via α2β1 integrin to support the growth and anti-inflammatory potency of mesenchymal stromal cells.

Understanding mesenchymal stromal cells (MSCs) growth mechanisms in response to surface chemistries is essential to optimize culture methods for high-quality and robust cell yields in cell manufacturing applications. Heparin (HEP) and collagen 1 (COL) substrates have been reported to enhance cell adhesion, growth, viability, and secretory potential in MSCs. However, the biomolecular mechanisms underlying the benefits of combined HEP/COL substrates are unknown. This work used HEP/COL bilayered surfaces to investigate the role of integrin-HEP interactions in the advantages of MSC culture. The layer-by-layer approach (LbL) was used to create HEP/COL bilayers, which were made up of stacks of 8 and 9 layers that combined HEP and COL in an alternate arrangement. Surface spectroscopic investigations and laser scanning microscopy evaluations verified the biochemical fingerprint of each component and a total stacked bilayer thickness of roughly 150 nm. Cell growth and apoptosis in response to IC50 and IC75 levels of BTT-3033 and Cilengitide, α2β1 and αvβ3 integrin inhibitors respectively, were evaluated on HEP/COL coated surfaces using two bone marrow-derived MSC donors. While integrin activity did not affect cell growth rates, it significantly affected cell adhesion and apoptosis on HEP/COL surfaces. HEP-ending HEP/COL surfaces significantly increased FAK-ERK½ phosphorylation and endogenous cell COL deposition compared to COL, COL-ending HEP/COL and uncoated surfaces. BTT-3033 but not Cilengitide treatment markedly affected FAK-ERK½ activity levels on HEP-ending HEP/COL surfaces supporting a major role for α2β1 activity. BTT-3033 treatment on HEP-ending bilayers reduced MSC-mediated macrophage inhibitory activity and altered the cytokine profile of co-cultures. Overall, this study supports a novel role for HEP in regulating the survival and potency of MSCs via enhancing the α2β1-FAK-ERK½ signaling mechanism.

Compartmental Cerebrospinal Fluid Events Occurring after Subarachnoid Hemorrhage: An "Heparin Oriented" Systematic Review.

Subarachnoid hemorrhage (SAH) represents a severe acute event with high morbidity and mortality due to the development of early brain injury (EBI), secondary delayed cerebral ischemia (DCI), and shunt-related hydrocephalus. Secondary events (SSE) such as neuroinflammation, vasospasm, excitotoxicity, blood-brain barrier disruption, oxidative cascade, and neuronal apoptosis are related to DCI. Despite improvement in management strategies and therapeutic protocols, surviving patients frequently present neurological deficits with neurocognitive impairment. The aim of this paper is to offer to clinicians a practical review of the actually documented pathophysiological events following subarachnoid hemorrhage. To reach our goal we performed a literature review analyzing reported studies regarding the mediators involved in the pathophysiological events following SAH occurring in the cerebrospinal fluid (CSF) (hemoglobin degradation products, platelets, complement, cytokines, chemokines, leucocytes, endothelin-1, NO-synthase, osteopontin, matricellular proteins, blood-brain barrier disruption, microglia polarization). The cascade of pathophysiological events secondary to SAH is very complex and involves several interconnected, but also distinct pathways. The identification of single therapeutical targets or specific pharmacological agents may be a limited strategy able to block only selective pathophysiological paths, but not the global evolution of SAH-related events. We report furthermore on the role of heparin in SAH management and discuss the rationale for use of intrathecal heparin as a pleiotropic therapeutical agent. The combination of the anticoagulant effect and the ability to interfere with SSE theoretically make heparin a very interesting molecule for SAH management.

In vitro fermentation of heparin by the human gut microbiota: Changes in the microbiota community and metabolic functions

Levels of its utilization suggest that the host glycosaminoglycan heparin is an important carbohydrate in the human gut microbiota. However, the interaction between heparin and the gut microbiota is not well understood. In this study, an in vitro fermentation system combined with microbiome and metabolome technologies was used to study the interaction between heparin and the gut microbiota. Interestingly, we found that heparin can be used by the gut microbiota, which produce large amounts of short chain fatty acids leading to a decrease in pH. In addition, the addition of heparin increased the relative abundance of Bacteroides and Bifidobacterium and decreased the relative abundance of Escherichia-Shigella. Correlation analysis of the microbiome and metabolome revealed that the catabolism of heparin was accompanied by the biosynthesis of bile acids and tryptophan metabolism. Overall, this study provides new evidence on the role of heparin as a stable carbon source for the gut microbiota and forms a strong basis for the use of heparin to condition the gut microbiota.

Clinical evaluation of the safety and efficacy of enoxaparin in patients with COVID-19.

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), increases thrombotic risk in hospitalised patients. The rate of thrombosis in patients with COVID-19 is unclear. The role of heparin, frequently used in the management of hospitalised patients, also needs to be clarified. In this study, we investigated the efficacy and safety of enoxaparin given at prophylactic or therapeutic dose in hospitalised patients with COVID-19, and evaluated its role in the development of disease in terms of mortality, and incidence of thrombotic and bleeding events. We included 141 patients with SARS-CoV-2 infection, admitted to five different wards (one intensive care unit, 2 sub-intensive care units, and 2 general infectious disease units) of Cotugno Hospital, a tertiary care hospital in Naples, Italy, between March and May 2020. Over a median time of 17 days (IQR 11-25), enoxaparin was given to 90/141 patients (63.8%) of whom 65 took a prophylactic and 25 a therapeutic dose. We documented 14 episodes of thrombosis (9.9%); almost all were cases of pulmonary embolism. No significant difference in terms of thromboembolic prevention was found between those patients not receiving anticoagulants and those on prophylactic or therapeutic dose of enoxaparin. Five episodes of major bleeding occurred (3.5%); therapeutic dose of enoxaparin was associated with a greater bleeding risk than prophylactic dose (p=0.002). During follow-up, 31 patients (22%) died; these were mostly elderly men with two or more comorbidities at admission. No advantages of enoxaparin, either as prophylaxis or at high doses, in terms of mortality were observed. At multivariate analysis, low estimated glomerular filtration rate, and high total bilirubin and fasting hyperglycemia were independently associated with a higher mortality. We did not observe advantages in terms of either thromboembolic prevention or mortality of enoxaparin, which however was more frequently used in patients with more severe disease. Prophylactic enoxaparin was not seen to be associated with bleeding risk.

Ultrasound-induced destruction of heparin-loaded microbubbles attenuates L-arginine-induced acute pancreatitis

PurposeAcute pancreatitis (AP) involves sudden inflammation caused by abnormal activation of pancreatic enzymes. The mechanisms underlying AP include oxidative stress, high levels of inflammatory mediators and inflammatory cell infiltration. Heparin, a key therapeutic drug, exerts anti-inflammatory, antioxidative, and anticoagulative effects. However, safe and effective drug delivery remains an obstacle. This study is the first to investigate the therapeutic effects of heparin-loaded microbubbles (HPMB) combined with ultrasound (UHPMB) and the role of heparin in acoustic cavitation. MethodsThe characteristics of the microbubbles, including particle size, concentration, release, stability, and development, were studied. Heparin concentration in the HPMB was measured, and heparin-induced anticoagulation was evaluated. Drug safety was explored using hemolysis and cell viability assessments. The ability of HPMB to alleviate oxidative stress and inflammation were investigated in vitro. L-arginine induces AP in vivo. UHPMB was used for AP treatment. Serum amylase levels were measured and pancreatic architecture and pathological features were evaluated to determine AP severity. In vivo efficacy was evaluated, and the underlying mechanism of heparin action during acoustic cavitation was explored. ResultsHPMB was spherical and presented as an emulsion-like solution without aggregation. HPMB was visible and stable and effectively released the drug under ultrasound (US). HPMB and UHPMB led to lower AP severity than in the untreated group. US-targeted microbubble destruction (UTMD) enhanced the therapeutic effect by decreasing oxidative stress and inflammation in AP models without injuring vital organs. UHPMB regulated VEGF/Flt-1 and SOD-1 expression. HPMB can also mitigate oxidative stress and inflammation in H2O2-pretreated cells. ConclusionUHPMB exhibits a strong ability not only to selectively target pancreatic lesions and release heparin but also to provide efficient protection by inhibiting oxidative stress and inflammation.

An Additive-Free Model for Tau Self-Assembly.

Tau is a natively unfolded protein that contributes to the stability of microtubules. Under pathological conditions such as Alzheimer's disease (AD), tau protein misfolds and self-assembles to form paired helical filaments (PHFs) and straight filaments (SFs). Full-length tau protein assembles poorly and its self-assembly is enhanced with polyanions such as heparin and RNA in vitro, but a role for heparin or other polyanions in vivo remains unclear. Recently, a truncated form of tau (297-391) has been shown to self-assemble in the absence of additives which provides an alternative in vitro PHF model system. Here we describe methods to prepare in vitro PHFs and SFs from tau (297-391) named dGAE. We also discuss the range of biophysical/biochemical techniques used to monitor tau filament assembly and structure.

A potential new pathway for heparin treatment of sepsis-induced lung injury: inhibition of pulmonary endothelial cell pyroptosis by blocking hMGB1-LPS-induced caspase-11 activation.

Sepsis is a significant cause of mortality in critically ill patients. Acute lung injury (ALI) is a leading cause of death in these patients. Endothelial cells exposed to the bacterial endotoxin lipopolysaccharide (LPS) can progress into pyroptosis, a programmed lysis of cell death triggered by inflammatory caspases. It is characterized by lytic cell death induced by the binding of intracellular LPS to caspases 4/5 in human cells and caspase-11 in mouse cells. In mice,caspase-11-dependent pyroptosis plays an important role in endotoxemia. HMGB1 released into the plasma binds to LPS and is internalized into lysosomes in endothelial cells via the advanced glycation end product receptor. In the acidic lysosomal environment, HMGB1 permeates the phospholipid bilayer, which is followed by the leakage of LPS into the cytoplasm and the activation of caspase-11. Heparin is an anticoagulant widely applied in the treatment of thrombotic disease. Previous studies have found that heparin could block caspase-11-dependent inflammatory reactions, decrease sepsis-related mortality, and reduce ALI, independent of its anticoagulant activity. Heparin or modified heparin with no anticoagulant property could inhibit the alarmin HMGB1-LPS interactions, minimize LPS entry into the cytoplasm, and thus blocking caspase-11 activation. Heparin has been studied in septic ALI, but the regulatory mechanism of pulmonary endothelial cell pyroptosis is still unclear. In this paper, we discuss the potential novel role of heparin in the treatment of septic ALI from the unique mechanism of pulmonary endothelial cell pyroptosis.

Clinical Study of Deep Vein Thrombosis of Lower Limbs

Understanding the natural history of venous thrombosis is important for optimal management of this condition. Once risk factors are recognized it is possible to avoid these risk factors or to use active prophylaxis to reduce the morbidity and mortality. This study is targeted at identifying the risk factors of deep vein thrombosis in our set up, the role of Heparin in prophylaxis and to do a comparative study of low molecular weight Heparin with unfractionated Heparin in treatment of deep vein thrombosis of lower limb in Guru Gobind Singh Government hospital, Jamnagar. Material and Methods: Study population consisted of 50 consecutive patients with deep vein thrombosis, admitted to Guru Gobind Singh hospital, Jamnagar. We have studied 50 patients above 18 years of age with proven deep venous thrombosis by Doppler ultrasound. A complete clinical history was taken to assess risk factors, level of immobility if present and thorough physical examination was done. Routine investigations such as hemogram, haematocrit, blood indices, and liver and renal function tests were done. Diagnosis of deep vein thrombosis was detected by radiographic imaging like Doppler ultrasonography. Results: In our study, most of patients presented with complaints of swelling (70%) and pain (48%) of the affected lower limb. Few patients (4%) had symptoms of breathlessness (SOB), chest pain and orthopnea suggestive of pulmonary embolism. 34 patients in our study were having reasonably good level of haemoglobin while rests of all were having anaemia of different degree4 patients had haemoglobin below 8gm/dl and that needed separate treatment also. Leukocytosis was present in 16 patients. 16 patients had smoking as associated risk factor along with other acquired risk factors and 5 patients had obesity along with other risk factors. The most common complication of DVT is pulmonary embolism which occurs due to dislodgement of thrombus. Conclusion: Even though it is grievous, DVT can be prevented and treatable. Better and regular availability of drugs like LMWH and safer oral anticoagulants in the smallest possible region of the country can do wonders to save lives. Larger studies focusing more on coagulation cascade, molecular biology and genetics will be even bigger help to mankind.

The Role of Heparin in COVID-19: An Update after Two Years of Pandemics.

Coronavirus disease 2019 (COVID-19) is associated with an increased risk of venous thromboembolism (VTE) and coagulopathy, especially in critically ill patients. Endothelial damage induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is emerging as a crucial pathogenetic mechanism for the development of complications in an acute phase of the illness and for several postdischarge sequalae. Heparin has been shown to have a positive impact on COVID-19 due to its anticoagulant function. Moreover, several other biological actions of heparin were postulated: a potential anti-inflammatory and antiviral effect through the main protease (Mpro) and heparansulfate (HS) binding and a protection from the damage of vascular endothelial cells. In this paper, we reviewed available evidence on heparin treatment in COVID-19 acute illness and chronic sequalae, focusing on the difference between prophylactic and therapeutic dosage.

\u201cH\u201d is not for hydroxychloroquine\u2014\u201cH\u201d is for heparin: lack of efficacy of hydroxychloroquine and the role of heparin in COVID-19\u2014preliminary data of a prospective and interventional study from Brazil

BackgroundCOVID-19 pandemic is the major public health problem in the world actually. It’s associated with high morbidity and mortality. To date, no therapeutic measure has a curative potential. Hydroxychloroquine (HCQ) is a drug with immunomodulatory properties that has demonstrated antiviral efficacy in in vitro experiments, with conflicting results in in vivo studies.MethodsA single-center, prospective and interventional study, that evaluates the impact on mortality of the HCQ use in 154 patients hospitalized with COVID-19 in a Brazilian public hospital. The study also aims to determine prognostic factors that predict mortality, ICU admission and endotracheal intubation in this population.Results154 patients diagnosed with COVID-19 confirmed by RT-PCR and hospitalized were included. There was a male predominance (87/154, 56.5%), median age 60 years and 88% (136/154) had comorbidities. Among these, 76% (117/154) were admitted to the ICU and 29.2% (45/154) experienced EOT. The OMR was 51.3% (79/154). There was no difference in mortality between patients treated with HCQ (N = 95) and non-HCQ (N = 59) (44.1% × 55.8%, p = 0.758). In univariate analysis, age ≥ 60 years (HR 3.62, p < 0.001), need for mechanical ventilation (HR 2.17, p = 0.001), ≥ 2 comorbidities (HR 1.83, p = 0.049), SAH (HR: 1.56, p = 0.054) were predictors of mortality, as well as no use of prophylactic or therapeutic heparin (HR 3.60, p = 0.02). Multivariate analysis identified admission to the ICU (HR 8.98, p = 0.002) and advanced age (HR 3.37, p < 0.01) as independent predictors of mortality, although, use of heparin (HR 0.25, p = 0.001) was independently associated with a favorable outcome.ConclusionThis study confirmed the absence of a benefit associated with the use of HCQ in Brazilian patients hospitalized with COVID-19. However, prophylactic or therapeutic heparin was an independent predictor for reducing mortality in this population.

The Role of Heparin and Glycocalyx in Blood-Brain Barrier Dysfunction.

The blood-brain barrier (BBB) functions as a dynamic boundary that protects the central nervous system from blood and plays an important role in maintaining the homeostasis of the brain. Dysfunction of the BBB is a pathophysiological characteristic of multiple neurologic diseases. Glycocalyx covers the luminal side of vascular endothelial cells(ECs). Damage of glycocalyx leads to disruption of the BBB, while inhibiting glycocalyx degradation maintains BBB integrity. Heparin has been recognized as an anticoagulant and it protects endothelial glycocalyx from destruction. In this review, we summarize the role of glycocalyx in BBB formation and the therapeutic potency of heparin to provide a theoretical basis for the treatment of neurological diseases related to BBB breakdown.

Clinical evaluation of the safety and efficacy of enoxaparin in patients with COVID-19.

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), increases thrombotic risk in hospitalised patients. The rate of thrombosis in patients with COVID-19 is unclear. The role of heparin, frequently used in the management of hospitalised patients, also needs to be clarified. In this study, we investigated the efficacy and safety of enoxaparin given at prophylactic or therapeutic dose in hospitalised patients with COVID-19, and evaluated its role in the development of disease in terms of mortality, and incidence of thrombotic and bleeding events. We included 141 patients with SARS-CoV-2 infection, admitted to five different wards (one intensive care unit, 2 sub-intensive care units, and 2 general infectious disease units) of Cotugno Hospital, a tertiary care hospital in Naples, Italy, between March and May 2020. Over a median time of 17 days (IQR 11-25), enoxaparin was given to 90/141 patients (63.8%) of whom 65 took a prophylactic and 25 a therapeutic dose. We documented 14 episodes of thrombosis (9.9%); almost all were cases of pulmonary embolism. No significant difference in terms of thromboembolic prevention was found between those patients not receiving anticoagulants and those on prophylactic or therapeutic dose of enoxaparin. Five episodes of major bleeding occurred (3.5%); therapeutic dose of enoxaparin was associated with a greater bleeding risk than prophylactic dose (p=0.002). During follow-up, 31 patients (22%) died; these were mostly elderly men with two or more comorbidities at admission. No advantages of enoxaparin, either as prophylaxis or at high doses, in terms of mortality were observed. At multivariate analysis, low estimated glomerular filtration rate, and high total bilirubin and fasting hyperglycaemia were independently associated with a higher mortality. We did not observe advantages in terms of either thromboembolic prevention or mortality of enoxaparin, which however was more frequently used in patients with more severe disease. Prophylactic enoxaparin was not seen to be associated with bleeding risk.

Thromboelastography profiles for controlled circulatory death donors: Validating the role of heparin.

Controlled donation after circulatory death (cDCD) liver transplants are associated with increased ischemic-type biliary complications. Microvascular thrombosis secondary to decreased donor fibrinolysis may contribute to bile duct injury. We hypothesized that cDCD donors are hypercoagulable with impaired fibrinolysis and aim to use thromboelastography to characterize cDCD coagulation profiles.

D-Dimer and Thrombosis in COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has taken medical community by surprise, but it also saw significant advances in understanding of infection induced coagulopathy. Pulmonary and macrovascular thrombosis is one of the hallmarks of this pandemic and has intrigued vascular surgeons world over. In this review, the lessons learnt from COVID-19 coagulopathy are summarised with some perspectives on role of newer concepts of immune mediated thrombosis and endothelial inflammation. D-dimers have become one of the most discussed inflammatory marker and also one of the commonest blood tests ordered in the COVID-19 pandemic. Its usefulness in management of COVID induced thrombosis has been a matter of debate and this article looks in to evidence based application of D-dimer in clinical practice. Role of Heparins, Direct Oral Anticoagulants (DOACs) and anti-platelets in prophylaxis and management of vascular thrombosis has also been summarised.

Heparin impairs skeletal muscle glucose uptake by inhibiting insulin binding to insulin receptor

AimHeparin, a widely used antithrombotic drug has many other anticoagulant‐independent physiological functions. Here, we elucidate a novel role of heparin in glucose homeostasis, suggesting an approach for developing heparin‐targeted therapies for diabetes.MethodsFor serum heparin levels and correlation analysis, 122 volunteer’s plasma, DIO (4 weeks HFD) and db/db mice serums were collected and used for spectrophotometric determination. OGTT, ITT, 2‐NBDG uptake and muscle GLUT4 immunofluorescence were detected in chronic intraperitoneal injection of heparin or heparinase (16 days) and muscle‐specific loss‐of‐function mice. In 293T cells, the binding of insulin to its receptor was detected by fluorescence resonance energy transfer (FRET), Myc‐GLUT4‐mCherry plasmid was used in GLUT4 translocation. In vitro, C2C12 cells as mouse myoblast cells were further verified the effects of heparin on glucose homeostasis through 2‐NBDG uptake, Western blot and co‐immunoprecipitation.ResultsSerum concentrations of heparin are positively associated with blood glucose levels in humans and are significantly increased in diet‐induced and db/db obesity mouse models. Consistently, a chronic intraperitoneal injection of heparin results in hyperglycaemia, glucose intolerance and insulin resistance. These effects are independent of heparin’s anticoagulant function and associated with decreases in glucose uptake and translocation of glucose transporter type 4 (GLUT4) in skeletal muscle. By using a muscle‐specific loss‐of‐function mouse model, we further demonstrated that muscle GLUT4 is required for the detrimental effects of heparin on glucose homeostasis.ConclusionsHeparin reduced insulin binding to its receptor by interacting with insulin and inhibited insulin‐mediated activation of the PI3K/Akt signalling pathway in skeletal muscle, which leads to impaired glucose uptake and hyperglycaemia.

Патогенез COVID-19. Роль гепаринов в терапии тяжелых состояний у пациентов с COVID-19

The novel viral disease and its associated severe acute respiratory syndrome are currently the world's most significant public health crisis The main stages of alveolar injury are mediated by endothelial damage, which leads to the release of cytokines and chemokines, the recruitment of immune cells, and the activation of the coagulation system and thrombosis Numerous studies, including autopsy and histological data, confirm endothelial dysfunction in coronavirus infection and note an increased risk of venous thromboembolic events in patients with a severe course Increases in D-dimer and fibrinogen degradation products remain to be the main prognostically important laboratory criteria, correlating with a higher risk of severe disease and mortality Taking into account the presence of coagulopathy, heparins may be effective and affordable drugs for reducing the risk of severe acute respiratory syndrome Low-molecular-weight heparins reduce the release and activity of IL-6 that is responsible for the development of cytokine storm, which is associated with better outcomes in patients with severe COVID-19 In addition, the antiviral and anti-inflammatory activity of heparins should be taken into consideration, which is very important for leveling the release of pro-inflammatory cytokines and mitigating the damaging effect of the virus on the endothelium Conclusion At this stage of understanding the pathophysiology of coronavirus infection, it is worth considering the use of low-molecular-weight heparins in patients with severe COVID-19, including those with sepsis-induced coagulopathy The use of heparins in a therapeutic dosage has shown a significantly greater efficacy than that in prophylactic doses

Use of Enoxaparin to Counteract COVID-19 Infection and Reduce Thromboembolic Venous Complications: A Review of the Current Evidence.

The impact of the COVID-19 pandemic has been dramatic worldwide, with China, Italy, and now US at its epicenter. Researchers and clinicians are studying and testing different approaches in the attempt to prevent the infection and minimize its severity. Major efforts are focused on optimizing mechanical ventilation, antiviral, and supportive treatment; however, the role of heparin and low molecular weight (LMW) heparin in this setting has been largely overlooked. This review summarizes the available evidence about the role of heparan sulfate as a key entry mechanism for SARS-CoV-2; the efficacy of heparin and LMW heparin in counteracting its entry into the cell, the recent experimental findings obtained in in vitro studies using the LMW heparin enoxaparin Inhixa®, the role of heparin and LMW heparin in modulating the cytokine storm, and the evidence for the use of LMW heparin in the prevention and treatment of the thromboembolic complications of COVID-19. The available evidence suggests that LMW heparin appears as a promising tool in the treatment of COVID-19. Whether its systematic use is associated with a reduction in complications and ultimately mortality of these patients is being tested in several studies starting worldwide.

The Utility of Native MS for Understanding the Mechanism of Action of Repurposed Therapeutics in COVID-19: Heparin as a Disruptor of the SARS-CoV-2 Interaction with Its Host Cell Receptor.

The emergence and rapid proliferation of the novel coronavirus (SARS-CoV-2) resulted in a global pandemic, with over 6,000,000 cases and nearly 400,000 deaths reported worldwide by the end of May 2020. A rush to find a cure prompted re-evaluation of a range of existing therapeutics vis-à-vis their potential role in treating COVID-19, placing a premium on analytical tools capable of supporting such efforts. Native mass spectrometry (MS) has long been a tool of choice in supporting the mechanistic studies of drug/therapeutic target interactions, but its applications remain limited in the cases that involve systems with a high level of structural heterogeneity. Both SARS-CoV-2 spike protein (S-protein), a critical element of the viral entry to the host cell, and ACE2, its docking site on the host cell surface, are extensively glycosylated, making them challenging targets for native MS. However, supplementing native MS with a gas-phase ion manipulation technique (limited charge reduction) allows meaningful information to be obtained on the noncovalent complexes formed by ACE2 and the receptor-binding domain (RBD) of the S-protein. Using this technique in combination with molecular modeling also allows the role of heparin in destabilizing the ACE2/RBD association to be studied, providing critical information for understanding the molecular mechanism of its interference with the virus docking to the host cell receptor. Both short (pentasaccharide) and relatively long (eicosasaccharide) heparin oligomers form 1:1 complexes with RBD, indicating the presence of a single binding site. This association alters the protein conformation (to maximize the contiguous patch of the positive charge on the RBD surface), resulting in a notable decrease in its ability to associate with ACE2. The destabilizing effect of heparin is more pronounced in the case of the longer chains due to the electrostatic repulsion between the low-pI ACE2 and the heparin segments not accommodated on the RBD surface. In addition to providing important mechanistic information on attenuation of the ACE2/RBD association by heparin, the study demonstrates the yet untapped potential of native MS coupled to gas-phase ion chemistry as a means of facilitating rational repurposing of the existing medicines for treating COVID-19.