Comprehensive Landscape of Heparin Therapy for COVID-19

Immunity and Coagulation in COVID-19

Discovered in late 2019, the SARS-CoV-2 coronavirus has caused the largest pandemic of the 21st century, claiming more than seven million lives. In most cases, the COVID-19 disease caused by the SARS-CoV-2 virus is relatively mild and affects only the upper respiratory tract; it most often manifests itself with fever, chills, cough, and sore throat, but also has less-common mild symptoms. In most cases, patients do not require hospitalization, and fully recover. However, in some cases, infection with the SARS-CoV-2 virus leads to the development of a severe form of COVID-19, which is characterized by the development of life-threatening complications affecting not only the lungs, but also other organs and systems. In particular, various forms of thrombotic complications are common among patients with a severe form of COVID-19. The mechanisms for the development of thrombotic complications in COVID-19 remain unclear. Accumulated data indicate that the pathogenesis of severe COVID-19 is based on disruptions in the functioning of various innate immune systems. The key role in the primary response to a viral infection is assigned to two systems. These are the pattern recognition receptors, primarily members of the toll-like receptor (TLR) family, and the complement system. Both systems are the first to engage in the fight against the virus and launch a whole range of mechanisms aimed at its rapid elimination. Normally, their joint activity leads to the destruction of the pathogen and recovery. However, disruptions in the functioning of these innate immune systems in COVID-19 can cause the development of an excessive inflammatory response that is dangerous for the body. In turn, excessive inflammation entails activation of and damage to the vascular endothelium, as well as the development of the hypercoagulable state observed in patients seriously ill with COVID-19. Activation of the endothelium and hypercoagulation lead to the development of thrombosis and, as a result, damage to organs and tissues. Immune-mediated thrombotic complications are termed "immunothrombosis". In this review, we discuss in detail the features of immunothrombosis associated with SARS-CoV-2 infection and its potential underlying mechanisms.

The Preventive and Therapeutic Effects of Acute and Severe Inflammatory Disorders with Heparin and Heparinoid

Systematic inflammatory response syndrome (SIRS) and the accompanying sepsis pose a huge threat to human health worldwide. Heparin is a part of the standard supportive care for the disease. However, the molecular mechanism is not fully understood yet, and the potential signaling pathways that play key roles have not yet been elucidated. In this paper, the main findings regarding the molecular mechanisms associated with the beneficial effects of heparin, including inhibiting HMGB-1-driven inflammation reactions, histone-induced toxicity, thrombo-inflammatory response control and the new emerging mechanisms are concluded. To set up the link between the preclinical research and the clinical effects, the outcomes of the clinical trials are summarized. Then, the structure and function relationship of heparin is discussed. By providing an updated analysis of the above results, the paper highlights the feasibility of heparin as a possible alternative for sepsis prophylaxis and therapy.

Beyond Anticoagulation: A Comprehensive Review of Non-Vitamin K Oral Anticoagulants (NOACs) in Inflammation and Protease-Activated Receptor Signaling

Non-vitamin K oral anticoagulants (NOACs) have revolutionized anticoagulant therapy, offering improved safety and efficacy over traditional agents like warfarin. This review comprehensively examines the dual roles of NOACs-apixaban, rivaroxaban, edoxaban, and dabigatran-not only as anticoagulants, but also as modulators of inflammation via protease-activated receptor (PAR) signaling. We highlight the unique pharmacotherapeutic properties of each NOAC, supported by key clinical trials demonstrating their effectiveness in preventing thromboembolic events. Beyond their established anticoagulant roles, emerging research suggests that NOACs influence inflammation through PAR signaling pathways, implicating factors such as factor Xa (FXa) and thrombin in the modulation of inflammatory responses. This review synthesizes current evidence on the anti-inflammatory potential of NOACs, exploring their impact on inflammatory markers and conditions like atherosclerosis and diabetes. By delineating the mechanisms by which NOACs mediate anti-inflammatory effects, this work aims to expand their therapeutic utility, offering new perspectives for managing inflammatory diseases. Our findings underscore the broader clinical implications of NOACs, advocating for their consideration in therapeutic strategies aimed at addressing inflammation-related pathologies. This comprehensive synthesis not only enhances understanding of NOACs' multifaceted roles, but also paves the way for future research and clinical applications in inflammation and cardiovascular health.

Inhaled heparin: Past, present, and future

While heparin has traditionally served as a key anticoagulant in clinical practice for nearly a century, recent years have witnessed a growing interest in its role as a potent antiinflammatory and antiviral agent, as well as an anticancer agent. To address challenges with injection-based delivery, exploring patient-friendly routes such as oral and pulmonary delivery is crucial. This review specifically highlights the multiple therapeutic benefits of inhaled heparin. In summary, this review serves as a valuable source of information, providing deep insights into the diverse therapeutic advantages of inhaled heparin and its potential applications within clinical contexts.

Multifunctional nanocoatings with synergistic controlled release of zinc ions and cytokines for precise modulation of vascular intimal reconstruction

Vascular stent implantation remains the major therapeutic method for cardiovascular diseases currently. We here introduced crucial biological functional biological function factors (SDF-1α, VEGF) and vital metal ions (Zn2+) into the stent surface to explore their synergistic effect in the microenvironment. The combination of the different factors is known to effectively regulate cellular inflammatory response and selectively regulate cell biological behavior. Meanwhile, in the implemented method, VEGF and Zn2+ were loaded into heparin and poly-l-lysine (Hep-PLL) nanoparticles, ensuring a controlled release of functional molecules with a multi-factor synergistic effect and excellent biological functions in vitro and in vivo. Notably, after 150 days of implantation of the modified stent in rabbits, a thin and smooth new intima was obtained. This study offers a new idea for constructing a modified surface microenvironment and promoting tissue repair.

Biomedical applications of engineered heparin-based materials

Heparin is a negatively charged polysaccharide with various chain lengths and a hydrophilic backbone. Due to its fascinating chemical and physical properties, nontoxicity, biocompatibility, and biodegradability, heparin has been extensively used in different fields of medicine, such as cardiovascular and hematology. This review highlights recent and future advancements in designing materials based on heparin for various biomedical applications. The physicochemical and mechanical properties, biocompatibility, toxicity, and biodegradability of heparin are discussed. In addition, the applications of heparin-based materials in various biomedical fields, such as drug/gene delivery, tissue engineering, cancer therapy, and biosensors, are reviewed. Finally, challenges, opportunities, and future perspectives in preparing heparin-based materials are summarized.

Role of Surgical and Medical Management of Chronic Thromboembolic Pulmonary Hypertension: A Systematic Review

Chronic thromboembolic pulmonary hypertension (CTEPH) is underdiagnosed and has recently surfaced as one of the leading triggers of severe pulmonary hypertension. This disease process is described by structural changes of pulmonary arteries such as fibrous stenosis, complete obliteration, or the presence of a resistant intraluminal thrombus, resulting in increased pulmonary resistance and eventually progressing to right-sided heart failure. Hence, this study aims to describe the current treatments for CTEPH and their efficacy in hemodynamic improvement and prevention of recurring thromboembolic episodes in patients. This systematic review promptly follows the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. On February 13, 2022, our team searched through the following databases: PubMed, ProQuest, and ScienceDirect. The following keywords were used across all databases: CTEPH AND Pulmonary Endarterectomy (PEA), CTEPH AND Balloon Pulmonary Angioplasty (BPA), and CTEPH AND Medical Therapy OR Anticoagulation therapy. Twenty-nine thousand eighty-nine articles on current management techniques (PEA, Balloon angioplasty, anticoagulants) were selected, analyzed, and reviewed with each other. We found 19 articles concerning PEA, 15 concerning BPA, and six regarding anticoagulants. Most papers showed high success rates and promising evidence of PEA and anticoagulants as a post-operative regimen. BPA was the least preferred but is still reputable in patients unfit for invasive techniques. CTEPH is a condition presenting with either fibrous stenosis, complete obliteration of the artery, or a clogged thrombus. Recent studies have shown three techniques that physicians have used to treat CTEPH: balloon-pulmonary angioplasty, PEA, and medical management with anticoagulants. PEA followed by anticoagulants is preferred to balloon pulmonary angioplasties. CTEPH is an ongoing topic in research; as it continues to be researched, we hope to see more management techniques available.

PRO-2000 exhibits SARS-CoV-2 antiviral activity by interfering with spike-heparin binding

Here, we report on the anti-SARS-CoV-2 activity of PRO-2000, a sulfonated polyanionic compound. In Vero cells infected with the Wuhan, alpha, beta, delta or omicron variant, PRO-2000 displayed EC50 values of 1.1 μM, 2.4 μM, 1.3 μM, 2.1 μM and 0.11 μM, respectively, and an average selectivity index (i.e. ratio of cytotoxic versus antiviral concentration) of 172. Its anti-SARS-CoV-2 activity was confirmed by virus yield assays in Vero cells, Caco2 cells and A549 cells overexpressing ACE2 and TMPRSS2 (A549-AT). Using pseudoviruses bearing the SARS-CoV-2 spike (S), PRO-2000 was shown to block the S-mediated pseudovirus entry in Vero cells and A549-AT cells, with EC50 values of 0.091 μM and 1.6 μM, respectively. This entry process is initiated by interaction of the S glycoprotein with angiotensin-converting enzyme 2 (ACE2) and heparan sulfate proteoglycans. Surface Plasmon Resonance (SPR) studies showed that PRO-2000 binds to the receptor-binding domain (RBD) of S with a KD of 1.6 nM. Similar KD values (range: 1.2 nM-2.1 nM) were obtained with the RBDs of the alpha, beta, delta and omicron variants. In an SPR neutralization assay, PRO-2000 had no effect on the interaction between the RBD and ACE2. Instead, PRO-2000 was proven to inhibit binding of the RBD to a heparin-coated sensor chip, yielding an IC50 of 1.1 nM. To conclude, PRO-2000 has the potential to inhibit a broad range of SARS-CoV-2 variants by blocking the heparin-binding site on the S protein.

Rapid protocols to support COVID-19 clinical diagnosis based on hematological parameters

Purpose

In December 2019, the Covid-19 pandemic began in the world. To reduce mortality, in addiction to mass vaccination, it is necessary to massify and accelerate clinical diagnosis, as well as creating new ways of monitoring patients that can help in the construction of specific treatments for the disease.

Objective

In this work, we propose rapid protocols for clinical diagnosis of COVID-19 through the automatic analysis of hematological parameters using evolutionary computing and machine learning. These hematological parameters are obtained from blood tests common in clinical practice.

Method

We investigated the best classifier architectures. Then, we applied the particle swarm optimization algorithm (PSO) to select the most relevant attributes: serum glucose, troponin, partial thromboplastin time, ferritin, D-dimer, lactic dehydrogenase, and indirect bilirubin. Then, we assessed again the best classifier architectures, but now using the reduced set of features. Finally, we used decision trees to build four rapid protocols for Covid-19 clinical diagnosis by assessing the impact of each selected feature. The proposed system was used to support clinical diagnosis and assessment of disease severity in patients admitted to intensive and semi-intensive care units as a case study in the city of Paudalho, Brazil.

Results

We developed a web system for Covid-19 diagnosis support. Using a 100-tree random forest, we obtained results for accuracy, sensitivity, and specificity superior to 99%. After feature selection, results were similar. The four empirical clinical protocols returned accuracies, sensitivities and specificities superior to 98%.

Conclusion

By using a reduced set of hematological parameters common in clinical practice, it was possible to achieve results of accuracy, sensitivity, and specificity comparable to those obtained with RT-PCR. It was also possible to automatically generate clinical decision protocols, allowing relatively accurate clinical diagnosis even without the aid of the web decision support system.

Enoxaparin sodium bone cement displays local anti-inflammatory effects by regulating the expression of IL-6 and TNF-α

Objective

To explore the roles of Enoxaparin Sodium-Polymethyl methacrylate bone cement on inflammatory factors Interleukin-6 and Tumour Necrosis Factor-α in a rabbit knee replacement model. As well as the mechanisms underlying its potential effects on lipopolysaccharide-induced endothelial cell injury.

Methods

A knee replacement model was established using New Zealand rabbits. Forty rabbits were randomly divided into four groups: PMMA, ES-PMMA, sham-operated, and blank control groups (n = 10 in each group). Local tissues around the incision were taken at the 30th, 60th, and 90th minute after the surgical implantation of the corresponding bone cement. Immunohistochemistry in the surgical field was used to measure the expression of local inflammatory factors IL-6 and TNF-α. In the in vitro experiments, 1 cm³ of bone cement was immersed in 3 mL of the medium for 24 h. The bone cement was discarded and diluted to 25% with normal medium. Pre-experiments were screened for the best LPS-inducing concentration of 100 mg/mL, and the most compatible LPS concentration was used for subsequent experiments simulating the primary cultures of rats' Inferior Vena Cava Endothelial Cells. The experiments were divided into four groups: blank control group, LPS induction group, PMMA + LPS group, and ES-PMMA + LPS group. The apoptosis rate was detected by flow cytometry, and the expression levels of TNF-α and IL-6 in the cells and supernatant were measured by ELISA, western blotting, and immunofluorescence.

Results

According to immunohistochemical results, IL-6-positive cells were concentrated in the tissue interstitial space. In the PMMA and sham-operated groups, the number of IL-6-positive cells gradually increased over time. At all time points, IL-6 expression in the ES-PMMA group was much lower than in the PMMA and sham-operated groups. At 30 min, TNF-α positive cells in the ES-PMMA group expressed less than those in the PMMA and sham-operated groups, with no discernible difference between the PMMA and ES-PMMA groups at 60 or 90 min. Using ELISA and flow cytometry, the expression levels of IL-6 and TNF-α were improved and the apoptosis rate was magnified in the LPS-induced group (***P < 0.001) in contrast with the blank control group. Additionally, the expression levels of IL-6 and TNF-α were reduced in the ES-PMMA + LPS group compared with the LPS-induced group (*P < 0.05) and the apoptosis rate was reduced (***P < 0.001), with statistically significant variations. Western blotting and immunofluorescence analysis confirmed that IL-6 and TNF-α protein expression in cells was upregulated in the LPS-induced group compared to the blank control group (***P < 0.001), and the mean fluorescence intensity was enlarged (***P < 0.001). Meanwhile, IL-6 and TNF-α expression in the ES-PMMA + LPS group were down-regulated (**P < 0.01 or *P < 0.05) compared with the LPS-induced group and PMMA + LPS crew protein expression, and the average fluorescence intensity of IL-6 and TNF-α was lowered in the ES-PMMA + LPS group compared to the LPS-induced group (***P < 0.001).

Conclusions

ES-PMMA bone cement reduced the expression levels of local inflammatory factors IL-6 and TNF-α in a rabbit knee model. ES-PMMA bone cement reduced the rate of LPS-induced endothelial cell apoptosis and diminished local inflammatory damage by regulating the secretion of inflammatory factors TNF-α and IL-6.

Significance of heparin induced thrombocytopenia (HIT) in COVID-19: a systematic review and meta-analysis

Heparin-induced thrombocytopenia (HIT) occurs in approximately 3% of patients receiving heparinoids. About 30-75% of patients with type 2 of HIT develop thrombosis as a result of platelet activation. The most important clinical symptom is thrombocytopenia. Patients with severe COVID-19 are among those receiving heparinoids. This meta-analysis performed to picture the current knowledge and results of published studies in this field. Three search engines were searched and 575 papers were found. After evaluation, 37 articles were finally selected of which 13 studies were quantitatively analyzed. The pooled frequency rate of suspected cases with HIT in 13 studies with 11,241 patients was 1.7%. The frequency of HIT was 8.2% in the extracorporeal membrane oxygenation subgroup with 268 patients and 0.8% in the hospitalization subgroup with 10,887 patients. The coincidence of these two conditions may increase the risk of thrombosis. Of the 37 patients with COVID-19 and confirmed HIT, 30 patients (81%) were treated in the intensive care unit or had severe COVID-19. The most commonly used anticoagulants were UFH in 22 cases (59.4%). The median platelet count before treatment was 237 (176-290) x 10³/µl and the median nadir platelet count was 52 (31-90.5) x 10³/µl.

Sulfated polysaccharides act as baits to interfere with the binding of the spike protein (SARS-CoV-2) to the ACE2 receptor and can be administered through food

Human civilization is experiencing a global crisis involving an unprecedented viral pandemic, with a high mortality rate, uncontrolled spread, and few effective drugs for treatment. Here, we critically evaluate how sulfated polysaccharides can be applied via foods to reduce the infectious process and increase the chances of an adequate immune response. The approach is directed to the infectious process by SARS-CoV-2 and protein S as a therapeutic focus. We discuss the antiviral activities of certain natural and specific sulfated polysaccharides that bind tightly to protein S. Finally, we identified that sulfated polysaccharides act as baits to interfere with the binding of the spike protein (SARS-CoV-2) to the ACE2 receptor and can be administered through food.

Efficacy and Safety of Anticoagulant Therapy in COVID-19-Related Pulmonary Embolism with Different Extension

Pulmonary embolism (PE) has been associated with SARS-CoV-2 infection, and its incidence is highly variable. The aim of our study was to describe the radiological and clinical presentations, as well as the therapeutic management, of PEs that occurred during SARS-CoV-2 infection in a cohort of hospitalized patients. In this observational study, we enrolled patients with moderate COVID-19 who developed PE during hospitalization. Clinical, laboratory, and radiological features were recorded. PE was diagnosed on clinical suspicion and/or CT angiography. According to CT angiography results, two groups of patients were further distinguished: those with proximal or central pulmonary embolism (cPE) and those with distal or micro-pulmonary embolism (mPE). A total of 56 patients with a mean age of 78 ± 15 years were included. Overall, PE occurred after a median of 2 days from hospitalization (range 0-47 days) and, interestingly, the majority of them (89%) within the first 10 days of hospitalization, without differences between the groups. Patients with cPE were younger (p = 0.02), with a lower creatinine clearance (p = 0.04), and tended to have a higher body weight (p = 0.059) and higher D-Dimer values (p = 0.059) than patients with mPE. In all patients, low-weight molecular heparin (LWMH) at anticoagulant dosage was promptly started as soon as PE was diagnosed. After a mean of 16 ± 9 days, 94% of patients with cPE were switched to oral anticoagulant (OAC) therapy, which was a direct oral anticoagulant (DOAC) in 86% of cases. In contrast, only in 68% of patients with mPE, the prosecution with OAC was indicated. The duration of treatment was at least 3 months from PE diagnosis in all patients who started OAC. At the 3-month follow-up, no persistence or recurrence of PE as well as no clinically relevant bleedings were found in both groups. In conclusion, pulmonary embolism in patients with SARS-CoV-2 may have different extensions. Used with clinical judgment, oral anticoagulant therapy with DOAC was effective and safe.

Heparin, Low Molecular Weight Heparin, and Non-Anticoagulant Derivatives for the Treatment of Inflammatory Lung Disease

Unfractionated heparin has multiple pharmacological activities beyond anticoagulation. These anti-inflammatory, anti-microbial, and mucoactive activities are shared in part by low molecular weight and non-anticoagulant heparin derivatives. Anti-inflammatory activities include inhibition of chemokine activity and cytokine synthesis, inhibitory effects on the mechanisms of adhesion and diapedesis involved in neutrophil recruitment, inhibition of heparanase activity, inhibition of the proteases of the coagulation and complement cascades, inhibition of neutrophil elastase activity, neutralisation of toxic basic histones, and inhibition of HMGB1 activity. This review considers the potential for heparin and its derivatives to treat inflammatory lung disease, including COVID-19, ALI, ARDS, cystic fibrosis, asthma, and COPD via the inhaled route.

Low Molecular Weight Heparin, Anti-inflammatory/Immunoregulatory and Antiviral Effects, a Short Update

Low molecular weight heparin (LMWH) is a glycosaminoglycan long known for its anticoagulant properties. In recent times, recent evidence has associated this drug with extra pleiotropic anticoagulant effects that have also proven useful in the management of the treatment of COVID-19 infection indicating that heparin may play other roles in the management of the disease in addition to the prevention of thrombosis. Clinical observations and in vitro studies support that heparin has a potential multi-target effect. To date, the molecular mechanisms of these pleiotropic effects are not fully understood. This brief review presents some of the evidence from clinical and animal studies and describes the potential molecular mechanisms by which heparin may exert its anti-inflammatory/immunoregulatory and antiviral effects.

Heparin mimetics as potential intervention for COVID-19 and their bio-manufacturing

The COVID-19 pandemic has caused severe health problems worldwide and unprecedented decimation of the global economy. Moreover, after more than 2 years, many populations are still under pressure of infection. Thus, a broader perspective in developing antiviral strategies is still of great importance. Inspired by the observed multiple benefits of heparin in the treatment of thrombosis, the potential of low molecular weight heparin (LMWH) for the treatment of COVID-19 have been explored. Clinical applications found that LMWH decreased the level of inflammatory cytokines in COVID-19 patients, accordingly reducing lethality. Furthermore, several in vitro studies have demonstrated the important roles of heparan sulfate in SARS-CoV-2 infection and the inhibitory effects of heparin and heparin mimetics in viral infection. These clinical observations and designed studies argue for the potential to develop heparin mimetics as anti-SARS-CoV-2 drug candidates. In this review, we summarize the properties of heparin as an anticoagulant and the pharmaceutical possibilities for the treatment of virus infection, focusing on the perspectives of developing heparin mimetics via chemical synthesis, chemoenzymatic synthesis, and bioengineered production by microbial cell factories. The ultimate goal is to pave the eminent need for exploring novel compounds to treat coronavirus infection-caused diseases.

SARS-CoV-2 Infection Dysregulates Host Iron (Fe)-Redox Homeostasis (Fe-R-H): Role of Fe-Redox Regulators, Ferroptosis Inhibitors, Anticoagulants, and Iron-Chelators in COVID-19 Control

Severe imbalance in iron metabolism among SARS-CoV-2 infected patients is prominent in every symptomatic (mild, moderate to severe) clinical phase of COVID-19. Phase-I - Hypoxia correlates with reduced O₂ transport by erythrocytes, overexpression of HIF-1α, altered mitochondrial bioenergetics with host metabolic reprogramming (HMR). Phase-II - Hyperferritinemia results from an increased iron overload, which triggers a fulminant proinflammatory response - the acute cytokine release syndrome (CRS). Elevated cytokine levels (i.e. IL6, TNFα and CRP) strongly correlates with altered ferritin/TF ratios in COVID-19 patients. Phase-III - Thromboembolism is consequential to erythrocyte dysfunction with heme release, increased prothrombin time and elevated D-dimers, cumulatively linked to severe coagulopathies with life-threatening outcomes such as ARDS, and multi-organ failure. Taken together, Fe-R-H dysregulation is implicated in every symptomatic phase of COVID-19. Fe-R-H regulators such as lactoferrin (LF), hemoxygenase-1 (HO-1), erythropoietin (EPO) and hepcidin modulators are innate bio-replenishments that sequester iron, neutralize iron-mediated free radicals, reduce oxidative stress, and improve host defense by optimizing iron metabolism. Due to its pivotal role in 'cytokine storm', ferroptosis is a potential intervention target. Ferroptosis inhibitors such as ferrostatin-1, liproxstatin-1, quercetin, and melatonin could prevent mitochondrial lipid peroxidation, up-regulate antioxidant/GSH levels and abrogate iron overload-induced apoptosis through activation of Nrf2 and HO-1 signaling pathways. Iron chelators such as heparin, deferoxamine, caffeic acid, curcumin, α-lipoic acid, and phytic acid could protect against ferroptosis and restore mitochondrial function, iron-redox potential, and rebalance Fe-R-H status. Therefore, Fe-R-H restoration is a host biomarker-driven potential combat strategy for an effective clinical and post-recovery management of COVID-19.

The Role of Disordered Regions in Orchestrating the Properties of Multidomain Proteins: The SARS-CoV-2 Nucleocapsid Protein and Its Interaction with Enoxaparin

Novel and efficient strategies need to be developed to interfere with the SARS-CoV-2 virus. One of the most promising pharmaceutical targets is the nucleocapsid protein (N), responsible for genomic RNA packaging. N is composed of two folded domains and three intrinsically disordered regions (IDRs). The globular RNA binding domain (NTD) and the tethered IDRs are rich in positively charged residues. The study of the interaction of N with polyanions can thus help to elucidate one of the key driving forces responsible for its function, i.e., electrostatics. Heparin, one of the most negatively charged natural polyanions, has been used to contrast serious cases of COVID-19 infection, and we decided to study its interaction with N at the molecular level. We focused on the NTR construct, which comprises the NTD and two flanking IDRs, and on the NTD construct in isolation. We characterized this interaction using different nuclear magnetic resonance approaches and isothermal titration calorimetry. With these tools, we were able to identify an extended surface of NTD involved in the interaction. Moreover, we assessed the importance of the IDRs in increasing the affinity for heparin, highlighting how different tracts of these flexible regions modulate the interaction.

The cross-talk of lung and heart complications in COVID-19: Endothelial cells dysfunction, thrombosis, and treatment

The pandemic respiratory illness SARS-CoV-2 has increasingly been shown to be a systemic disease that can also have profound impacts on the cardiovascular system. Although associated cardiopulmonary sequelae can persist after infection, the link between viral infection and these complications remains unclear. There is now a recognized link between endothelial cell dysfunction and thrombosis. Its role in stimulating platelet activation and thrombotic inflammation has been widely reported. However, the procoagulant role of microparticles (MPs) in COVID-19 seems to have been neglected. As membrane vesicles released after cell injury or apoptosis, MPs exert procoagulant activity mainly by exposing phosphatidylserine (PS) on their lipid membranes. It can provide a catalytic surface for the assembly of the prothrombinase complex. Therefore, inhibiting PS externalization is a potential therapeutic strategy. In this paper, we describe the pathophysiological mechanism by which SARS-CoV-2 induces lung and heart complications through injury of endothelial cells, emphasizing the procoagulant effect of MPs and PS, and demonstrate the importance of early antithrombotic therapy. In addition, we will detail the mechanisms underlying hypoxia, another serious pulmonary complication related to SARS-CoV-2-induced endothelial cells injury and discuss the use of oxygen therapy. In the case of SARS-CoV-2 infection, virus invades endothelial cells through direct infection, hypoxia, imbalance of the RAAS, and cytokine storm. These factors cause endothelial cells to release MPs, form MPs storm, and eventually lead to thrombosis. This, in turn, accelerates hypoxia and cytokine storms, forming a positive feedback loop. Given the important role of thrombosis in the disease, early antithrombotic therapy is an important tool for COVID-19. It may maintain normal blood circulation, accelerating the clearance of viruses, waning the formation of MPs storm, and avoiding disease progression.

Low molecular weight heparin is associated with better outcomes than unfractionated heparin for thromboprophylaxis in hospitalized COVID-19 patients: a meta-analysis

AIMS

This study aimed to compare the outcomes of the administration of LMWH and UFH in hospitalized COVID-19 patients.

METHODS AND RESULTS

We systematically searched several databases and included observational studies or clinical trials that compared the outcomes of the administration of LMWH and UFH in hospitalized COVID-19 patients. A total of nine studies comprising 9637 patients were included. Metanalysis showed that LMWH administration was associated with a lower in-hospital mortality and 28/30-day mortality compared with UFH administration {[relative risk (RR) 0.44; 95% confidence interval (95% CI) 0.32-0.61; I2: 87.9%] and (RR 0.45; 95% CI 0.24-0.86; I2: 78.4%), respectively}. Patient with LMWH had shorter duration of hospital and ICU length of stay compared with UFH {[weighted mean difference (WMD) -2.20; 95% CI -3.01 to -1.40; I2:0%] and (WMD -1.41; 95% CI -2.20 to -0.63; I2: 0%), respectively}. The risk of ICU admission or mechanical ventilation was lower in patients who received LMWH than in those who received UFH (RR 0.67; 95% CI 0.55-0.81; I2: 67.3%). However, there was no difference in the incidence of bleeding with LMWH compared with UFH (RR 0.27; 95% CI 0.07-1.01; I2: 64.6%).

CONCLUSION

Our meta-analysis showed that administration of LMWH was associated with better outcomes compared with UFH in hospitalized COVID-19 patients. Prospective cohorts and RCTs are urgently needed to explore the definitive effect of LMWH to provide direct high-certainty evidence. PROSPERO registration number: CRD42021271977.

Inhaled heparin polysaccharide nanodecoy against SARS-CoV-2 and variants

The heparin polysaccharide nanoparticles block the interaction between heparan sulfate/S protein and inhibit the infection of both wild-type SARS-CoV-2 pseudovirus and the mutated strains through pulmonary delivery.Image 1.

Targeting of Glycosaminoglycans in Genetic and Inflammatory Airway Disease

In the lung, glycosaminoglycans (GAGs) are dispersed in the extracellular matrix (ECM) occupying the interstitial space between the capillary endothelium and the alveolar epithelium, in the sub-epithelial tissue and in airway secretions. In addition to playing key structural roles, GAGs contribute to a number of physiologic processes ranging from cell differentiation, cell adhesion and wound healing. Cytokine and chemokine–GAG interactions are also involved in presentation of inflammatory molecules to respective receptors leading to immune cell migration and airway infiltration. More recently, pathophysiological roles of GAGs have been described. This review aims to discuss the biological roles and molecular interactions of GAGs, and their impact in the pathology of chronic airway diseases, such as cystic fibrosis and chronic obstructive pulmonary disease. Moreover, the role of GAGs in respiratory disease has been heightened by the current COVID-19 pandemic. This review underlines the essential need for continued research aimed at exploring the contribution of GAGs in the development of inflammation, to provide a better understanding of their biological impact, as well as leads in the development of new therapeutic agents.

Investigation of predictors of bleeding complications in COVID-19 using rotational thromboelastometry (ROTEMⓇ): A retrospective study

Background

Hemorrhagic complications in patients with coronavirus 19 disease (COVID-19) are infrequent but associated with a prognosis. This study aimed to elucidate the risk factors for bleeding complications in patients with COVID-19 using rotational thromboelastometry (ROTEM) parameters and blood tests performed at admission.

Methods

In total, 31 patients with severe COVID-19 treated intensively at Saga University Hospital were included in this study. Patients were divided into two groups according to the presence or absence of hemorrhagic complications. Results from the blood tests performed at admission and during hospitalization, and ROTEM values acquired upon admission, were compared between the two groups.

Results

There were significant differences in ROTEM values upon admission between the bleeding and non-bleeding groups. Receiver operating curve analysis showed that the area under the curve for prothrombin time international normalized ratio (PT-INR) and extrinsically-activated test with tissue factor (EXTEM) amplitude at 10 min (A10) were 0.82 (0.52-0.92) and 0.81 (0.58-0.93), respectively. Logistic regression analysis with PT-INR and EXTEM A10 as factors calculated an odds ratio of 1.94 (1.04-3.62) and EXTEM A10 0.86 (0.71-1.05) for bleeding complications occurrence.

Conclusion

ROTEM may be a sensitive predictor for bleeding complications in patients with COVID-19.

Non-Specific Targets for Correction of Pneumonia Caused by Aerosols Containing Damaging Factors of Various Nature

This review article provides data on the current state of the pathogenesis peculiarities of body and lung inflammation (pneumonia) under the influence of damaging factors of various nature: infectious agents, chemical toxicants, as well as incorporated radionuclides, etc. The peculiarities of inflammation itself, as a typical pathological process, are considered. Information on mediators that induce the so-called pro-resolving phase of inflammation manifestations is given. Approaches to the neuroimmune correction of non-specific inflammation are substantiated. Data on the following alternative approaches to the correction of nonspecific inflammation are summarized: factors of the coagulation system, modulators of the integrated stress response, and modulators of sigma-1 receptors. Based on the data presented, general directions for the treatment of nonspecific pneumonia are formulated, including reflexogenic and anti-inflammatory therapy in combination with multimodal drugs, as well as pro-resolving therapy in combination with drugs that prevent fibrosis.

Bioactive Carbohydrate Polymers-Between Myth and Reality

Polysaccharides are complex macromolecules long regarded as energetic storage resources or as components of plant and fungal cell walls. They have also been described as plant mucilages or microbial exopolysaccharides. The development of glycosciences has led to a partial and difficult deciphering of their other biological functions in living organisms. The objectives of glycobiochemistry and glycobiology are currently to correlate some structural features of polysaccharides with some biological responses in the producing organisms or in another one. In this context, the literature focusing on bioactive polysaccharides has increased exponentially during the last two decades, being sometimes very optimistic for some new applications of bioactive polysaccharides, notably in the medical field. Therefore, this review aims to examine bioactive polysaccharide, taking a critical look of the different biological activities reported by authors and the reality of the market. It focuses also on the chemical, biochemical, enzymatic, and physical modifications of these biopolymers to optimize their potential as bioactive agents.

SARS-CoV-2 spike protein causes blood coagulation and thrombosis by competitive binding to heparan sulfate

Thrombotic complication has been an important symptom in critically ill patients with COVID-19. It has not been clear whether the virus spike (S) protein can directly induce blood coagulation in addition to inflammation. Heparan sulfate (HS)/heparin, a key factor in coagulation process, was found to bind SARS-CoV-2 S protein with high affinity. Herein, we found that the S protein can competitively inhibit the bindings of antithrombin and heparin cofactor II to heparin/HS, causing abnormal increase in thrombin activity. SARS-CoV-2 S protein at a similar concentration (~10 μg/mL) as the viral load in critically ill patients can cause directly blood coagulation and thrombosis in zebrafish model. Furthermore, exogenous heparin/HS can significantly reduce coagulation caused by S protein, pointing to a potential new direction to elucidate the etiology of the virus and provide fundamental support for anticoagulant therapy especially for the COVID-19 critically ill patients.

Early Effects of Low Molecular Weight Heparin Therapy with Soft-Mist Inhaler for COVID-19-Induced Hypoxemia: A Phase IIb Trial

In COVID-19-induced acute respiratory distress syndrome, the lungs are incapable of filling with sufficient air, leading to hypoxemia that results in high mortality among hospitalized patients. In clinical trials, low-molecular-weight heparin was administered via a specially designed soft-mist inhaler device in an investigator initiated, single-center, open-label, phase-IIb clinical trial. Patients with evidently worse clinical presentations were classed as the “Device Group”; 40 patients were given low-molecular-weight heparin via a soft mist inhaler at a dose of 4000 IU per administration, twice a day. The Control Group, also made up of 40 patients, received the standard therapy. The predetermined severity of hypoxemia and the peripheral oxygen saturation of patients were measured on the 1st and 10th days of treatment. The improvement was particularly striking in cases of severe hypoxemia. In the 10-day treatment, low-molecular-weight heparin was shown to significantly improve breathing capability when delivered via a soft-mist inhaler.

Comparison of the Effect of Unfractionated Heparin and Enoxaparin Sodium at Different Doses on the Course of COVID-19-Associated Coagulopathy

BACKGROUND

COVID-19-associated coagulopathy (CAC) exacerbates the course of coronavirus infection and contributes to increased mortality. Current recommendations for CAC treatment include the use of low-molecular weight heparins (LMWH) at prophylactic or therapeutic doses, as well as the use of unfractionated heparin (UFH).

METHODS

A randomised, controlled trial enrolled 126 patients hospitalised in the intensive care unit with severe COVID-19 complicated by CAC. The effects of LMWH at preventive and therapeutic doses and UFH at therapeutic doses on mortality and intubation rates were compared.

RESULTS

The number of intubations and deaths showed no significant difference depending on the anticoagulant therapy used. However, multivariate logistic regression models revealed an increased risk of intubation (p = 0.026, odds ratio (OR) = 3.33, 95% confidence interval (CI) 1.15-9.59), and an increased risk of death (p = 0.046, OR = 3.01, 95% CI 1.02-8.90), for patients treated with LMWH at a prophylactic dose but not at a therapeutic dose as compared to patients treated with UFH when controlling for other risk factors.

CONCLUSIONS

The use of unfractionated heparin in the treatment of COVID-19-associated coagulopathy seems to be more effective at reducing the risk of intubation and death than enoxaparin at prophylactic doses.

Thromboprophylaxis strategies to improve the prognosis of COVID-19

The outbreak of 2019 novel coronavirus disease (Covid-19) has deeply challenged the world population, but also our medical knowledge. Special attention has been paid early to an activation of coagulation, then to an elevated rate of venous thromboembolism (VTE) in patients hospitalized with severe COVID-19. These data suggested that anticoagulant drugs should be evaluated in the treatment of patients with COVID-19. The publication of unexpected high rates of VTE in patients hospitalized with COVID-19, despite receiving thromboprophylaxis, open the way to dedicated trials, evaluating modified regimens of thromboprophylaxis. Moreover, the further improvement in our comprehension of the disease, particularly the pulmonary endothelial dysfunction increased the hope that anticoagulant drugs may also protect patients from pulmonary thrombosis. In this comprehensive review, we cover the different situations where thromboprophylaxis standard may be modified (medically-ill inpatients, ICU inpatients, outpatients), and describe some of the current randomized controls trials evaluating new regimens of thromboprophylaxis in patients with COVID-19, including the preliminary available results. We also discuss the potential of anticoagulant drugs to target the thromboinflammation described in patients with severe COVID-19.

Heparin dosage, level, and resistance in SARS-CoV2 infected patients in intensive care unit

Introduction

Patients with COVID‐19 frequently exhibit a hypercoagulable state with high thrombotic risk, particularly those admitted to intensive care units (ICU). Thromboprophylaxis is mandatory in these patients; nevertheless, thrombosis still occurs in many cases. Thus, the problem of assessing an adequate level of anticoagulation in ICU patients becomes evident during the COVID‐19 pandemic. The aim of this study was to evaluate the heparin resistance and the efficacy of heparin monitoring using an anti‐Xa activity assay.

Methods

Thirty‐seven heparin‐treated patients admitted to ICU for SARS‐CoV‐2 pneumonia were retrospectively studied for antifactor Xa activity (anti‐Xa), activated partial thromboplastin time (APTT), Antithrombin, Fibrinogen, D‐Dimer, Factor VIII, von Willebrand Factor, and the total daily amount of heparin administered. The correlation between APTT and anti‐Xa was evaluated for unfractionated heparins (UFH). The correlations between the daily dose of UFH or the dosage expressed as IU/kg b.w. for low molecular weight heparin (LMWH) and anti‐Xa were also evaluated.

Results

Twenty‐one patients received calcium heparin, 8 sodium heparin, and 8 LMWH. A moderate correlation was found between APTT and anti‐Xa for UFH. APTT did not correlate with coagulation parameters. 62% of UFH and 75% of LMWH treated patients were under the therapeutic range. About 75% of patients could be considered resistant to heparin.

Conclusions

SARS‐COV2 pneumonia patients in ICU have frequently heparin resistance. Anti‐Xa seems a more reliable method to monitor heparin treatment than APTT in acute patients, also because the assay is insensitive to the increased levels of fibrinogen, FVIII, and LAC that are common during the COVID‐19 inflammatory state.

Elucidating the Interactions Between Heparin/Heparan Sulfate and SARS-CoV-2-Related Proteins-An Important Strategy for Developing Novel Therapeutics for the COVID-19 Pandemic

Owing to the high mortality and the spread rate, the infectious disease caused by SARS-CoV-2 has become a major threat to public health and social economy, leading to over 70 million infections and 1. 6 million deaths to date. Since there are currently no effective therapeutic or widely available vaccines, it is of urgent need to look for new strategies for the treatment of SARS-CoV-2 infection diseases. Binding of a viral protein onto cell surface heparan sulfate (HS) is generally the first step in a cascade of interaction that is required for viral entry and the initiation of infection. Meanwhile, interactions of selectins and cytokines (e.g., IL-6 and TNF-α) with HS expressed on endothelial cells are crucial in controlling the recruitment of immune cells during inflammation. Thus, structurally defined heparin/HS and their mimetics might serve as potential drugs by competing with cell surface HS for the prevention of viral adhesion and modulation of inflammatory reaction. In this review, we will elaborate coronavirus invasion mechanisms and summarize the latest advances in HS-protein interactions, especially proteins relevant to the process of coronavirus infection and subsequent inflammation. Experimental and computational techniques involved will be emphasized.