Evaluation of anticoagulant agents for the treatment of human metapneumovirus infection in mice

The Role of ACE2 Receptor and Its Polymorphisms in COVID-19 Infection and Severity and Its Association with Lipid Profile, Thrombin, and D-Dimer Levels in Iraqi Patients: A Cross-Sectional Study

COVID-19 patients experience a complex interplay involving ACE2, thrombin, D-dimer, and lipid profile, yet its full understanding remains elusive. ACE2, a pivotal regulator of the renin-angiotensin system and the primary receptor for SARS-CoV-2 undergoes downregulation upon viral binding, potentially leading to severe cases with acute respiratory distress syndrome (ARDS). A specific ACE2 gene polymorphism (rs2285666) may be associated with COVID-19 susceptibility, with the A allele potentially increasing infection risk. COVID-19 disease progression is linked to coagulation abnormalities, but the exact connection with thrombin and D-dimer remains uncertain. A study examining coagulation parameters in COVID-19 patients admitted to Al-Diwania Educational Hospital from February to May 2022 found that thrombin and D-dimer levels were directly related to disease severity. Severe cases exhibited significantly altered coagulation function compared to mild and recovered cases, with notably higher D-dimer levels and elevated thrombin serum concentrations. Moreover, dyslipidemia, particularly low HDL cholesterol, is a prevalent comorbidity in COVID-19 patients and may be linked to worse outcomes. In conclusion, COVID-19 is associated with a prothrombotic state and dysregulation of the renin-angiotensin system due to ACE2 downregulation following viral binding. The intricate interplay between ACE2, thrombin, D-dimer, and lipid profile necessitates further investigation. The multifaceted nature of the disease demands continued research to unravel its pathogenesis and identify potential therapeutic targets.

Development of pharmacophore models for AcrB protein and the identification of potential adjuvant candidates for overcoming efflux-mediated colistin resistance

Growing multi-drug resistance (MDR) among ESKAPE pathogens is a huge challenge. Increased resistance to last-resort antibiotics, like colistin, has further aggravated this. Efflux is identified as a major route of colistin resistance. So, finding an FDA-approved efflux inhibitor for potential application as an adjuvant to colistin was the primary objective of this study. E. coli-AcrB pump inhibitors and substrates were used to develop and validate the pharmacophoric model. Drugs confirming this pharmacophore were subjected to molecular docking to identify hits for the AcrB binding pocket. The efflux inhibition potential of the top hit was validated through the in vitro evaluation of the minimum inhibitory concentration (MIC) in combination with colistin. The checkerboard assay was done to demonstrate synergism, which was further corroborated by the Time-kill assay. Ten common pharmacophore hypotheses were successfully generated using substrate/inhibitors. Following enrichment analysis, AHHNR.100 was identified as the top-ranked hypothesis, and 207 unique compounds were found to conform to this hypothesis. The multi-step docking of these compounds against the AcrB protein revealed argatroban as the top non-antibiotic hit. This significantly inhibited the efflux activity of colistin-resistant clinical isolates K. pneumoniae (n = 1) and M. morganii (n = 2). Further, their combination with colistin enhanced the susceptibility of these isolates, and the effect was found to be synergistic. Accordingly, the time-kill assay of this combination showed 8-log and 2-log reductions against K. pneumoniae and M. morganii, respectively. In conclusion, this study found argatroban as a bacterial efflux inhibitor that can be potentially used to overcome efflux-mediated resistance.

The Potential Role of Coagulation Factor Xa in the Pathophysiology of COVID-19: A Role for Anticoagulants as Multimodal Therapeutic Agents

SARS-CoV-2 infection (COVID-19) results in local and systemic activation of inflammation and coagulation. In this review article, we will discuss the potential role of coagulation factor Xa (FXa) in the pathophysiology of COVID-19. FXa, a serine protease, has been shown to play a role in the cleavage of SARS-CoV-1 spike protein (SP), with the inhibition of FXa resulting in the inhibition of viral infectivity. FX is known to be primarily produced in the liver, but it is also expressed by multiple cells types, including alveolar epithelium, cardiac myocytes, and macrophages. Considering that patients with preexisting conditions, including cardiopulmonary disease, are at an increased risk of severe COVID-19, we discuss the potential role of increased levels of FX in these patients, resulting in a potential increased propensity to have a higher infectious rate and viral load, increased activation of coagulation and inflammation, and development of fibrosis. With these observations in mind, we postulate as to the potential therapeutic role of FXa inhibitors as a prophylactic and therapeutic treatment for high-risk patients with COVID-19.

Thrombin Inhibition by Argatroban: Potential Therapeutic Benefits in COVID-19

Thrombin is a trypsin-like serine protease with multiple physiological functions. Its role in coagulation and thrombosis is well-established. Nevertheless, thrombin also plays a major role in inflammation by activating protease-activated receptors. In addition, thrombin is also involved in angiogenesis, fibrosis, and viral infections. Considering the pathogenesis of COVID-19 pandemic, thrombin inhibitors may exert multiple potential therapeutic benefits including antithrombotic, anti-inflammatory, and antiviral activities. In this review, we describe the clinical features of COVID-19, the thrombin’s roles in various pathologies, and the potential of argatroban in COVID-19 patients. Argatroban is a synthetic, small molecule, direct, competitive, and selective inhibitor of thrombin. It is approved to parenterally prevent and/or treat heparin-induced thrombocytopenia in addition to other thrombotic conditions. Argatroban also possesses anti-inflammatory and antiviral activities and has a well-established pharmacokinetics profile. It also appears to lack a significant risk of drug–drug interactions with therapeutics currently being evaluated for COVID-19. Thus, argatroban presents a substantial promise in treating severe cases of COVID-19; however, this promise is yet to be established in randomized, controlled clinical trials.