Adenosine A2A Receptor (A2AR) Agonist Apadenoson Promotes Survival in K28-hACE2 Mice and Syrian Hamsters Infected with Sars-CoV-2

Purpose: To determine if Apadenoson or Regadenoson has a therapeutic effect in attenuating hyper-inflammation and improving survival rate in K18-hACE2mice or Syrian hamsters infected with SARS-CoV-2. Method(s): 6-8 weeks old male K18-hACE2mice were divided into Control group that received vehicle;Test group 1 that received the drug (Apadenoson or Regadenoson) 24hrs prior to challenge with SARS-CoV-2;and Test Group 2 (Drug-delay), that received the drug with a 5 hr delay post-viral infection (n=6/grp). Viral dose was 1250 PfuHong Kong/VM20001061/2020 delivered via intranasal route. Drug was delivered subcutaneously using 1007D ALZET pumps. 6 weeks old Syrian hamsters were divided into Control group that received Vehicle and Virus (n=4) and 2 test groups (n=5/group) that received Apadenoson+Virus and Regadenoson+Virus. Drugs were delivered by 2ML2 ALZET pumps (4ug/kg/hr). Hamsters were inoculated intratracheally with 750PFU SARS-CoV-2 WA1 strain prior to treatment. Mice were weighed and clinical scores recorded daily. Bronchoalveolar lavage fluid (BALF) and serum were collected along with lungs. Plethysmography was done on days 0, 2, 4 and 7. Result(s): Apadenoson administered post-infection was efficacious in decreasing weight loss, improving clinical score, and increasing the survival rate in K18-hACE2 mice, i.e. 50% survival was observed at Day 5 and at Day 7 post-infection for drug given before or after infection respectively. Apadenoson given post-infection improved the histopathology that was observed in the vehicle control group, decreased pro-inflammatory IL-6, IFN-gamma, MCCP-1, MIP-1beta, IP-10, and Rantes in serum, increased anti-inflammatory Ang1-7 levels, and decreased monocytes in BALF. 42% of mice that received Regadenoson pre-challenge survived infection compared to 6.25% in the vehicle or Drug delay (drug given post-infection) groups. Viral titers in the lungs of Regadenoson-treated mice were found decreased. Treatment also significantly decreased CD4+, CD8+T cells, eosinophils, and neutrophils in BALF. Plethysmography, in hamsters, showed significant improvement of pulmonary function parameters, Rpef and PenH, following treatment with Apadenoson given post-infection. Apadenoson cleared the virus from BALF and maintained Ang1-7 levels. Both drugs decreased plasma IFN-gamma levels. Conclusion(s): Treatment with Apadenoson attenuated inflammation, improved pulmonary function, decreased weight loss, and enhanced survival rate following infection with SARS-CoV-2 virus. The results demonstrate the translational significance of Apadenoson in the treatment of COVID-19.

American Society for Clinical Pharmacology and Therapeutics - 123rd Annual Meeting. Virtual - March 16-18, 2022

The 2022 American Society for Clinical Pharmacology and Therapeutics (ASCPT) Annual Meeting held virtually, with "Disruptive innovation" as the motto, offered attendees an outstanding scientific program focused on clinical pharmacology, translational medicine, drug discovery and drug development. It is the most important event for scientists involved in clinical pharmacology and translational medicine. The ASCPT conference offers scientists from different professional scopes and around the world the perfect opportunity to discuss emerging science. It focuses on improving the understanding and use of existing drug therapies and developing safer and more effective treatments for the future. Oral and poster presentations were available for participants during the running of the conference to accommodate the different time zones. Presentations covered the latest research with the option to ask questions after each presentation via a chat function. Discussion boards were available to provide networking opportunities for virtual attendees.

Role of adenosine receptors in cardiovascular disorders and novel corona virus infection

Objective: To assess the importance of adenosine signaling in cardiovascular disorders (thrombosis, ischemia) and novel corona virus infection. Methodology: A specified web search was done to gather the relevant information using different scientific research forums and databases like WHO database, Pubmed and Google Scholar etc. Results: Adenosine receptors are P1 type of purinergic receptors and belong to G protein-coupled receptors (GPCRs), which is the largest family of integral membrane bound proteins receptors. Adenosine receptors are further classified into four subclasses known as A1, A2A, A2B, and A3. All four subclasses are being mediated by extracellular adenosine and perform a key role in a wide range of physiological functions such as immune system modulation, angiogenesis and sleep regulation. Adenosine receptors are thought to play a significant role in many pathophysiological conditions including cardiovascular disorders such as ischemia and thrombosis and novel corona virus infection making it a key target against these disorders. Conclusion: We suggest that modulation of adenosine receptor activity could increase the regenerative phase in these disorders by increasing the proliferation and differentiation rates of damaged tissue.

Istradefylline, an adenosine A2a receptor antagonist, inhibits the CD4+ T-cell hypersecretion of IL-17A and IL-8 in humans.

Extracellular adenosine produced from ATP plays a role in energy processes, neurotransmission, and inflammatory responses. Istradefylline is a selective adenosine A2a receptor (A2aR) antagonist used for the treatment of Parkinson's disease. We previously showed using mouse models that adenosine primes hypersecretion of interleukin (IL)-17A via A2aR, which plays a role in neutrophilic inflammation models in mice. This finding suggests that adenosine is an endogenous modulator of neutrophilic inflammation. We, therefore, investigated the in vitro effect of istradefylline in humans. In the present study, using human peripheral blood mononuclear cells (PBMCs), we tested the effect of adenosine, adenosine receptor agonists and istradefylline on cytokine responses using mixed lymphocyte reaction (MLR), PBMCs, CD4+ T cells, and Candida albicans antigen (Ag)-stimulated PBMCs. We showed that adenosine and an A2aR agonist (PSB0777) promoted IL-17A and IL-8 production from human PBMCs, and istradefylline suppressed this response. In addition, istradefylline inhibited not only the IL-17A and IL-8 production induced by adenosine but also that from C. albicans Ag-stimulated PBMCs. These results indicate that adenosine-mediated IL-17A and IL-8 production plays a role in neutrophilic inflammation, against which istradefylline should be effective.

Adenosine-based cancer immunotherapy for COVID-19

Cancer immunotherapy has shaped the way in which we design cancer treatments, introducing the paradigm of taking advantage of our immune system to fight cancer. We propose that the same concept could be applied to infectious diseases and, especially, to those that hamper the immune system like COVID-19. It is well known that an adaptive immune response is able to eradicate viral infections and CD8+ T-cells are key in such anti-viral response. Furthermore, several studies reported that the number of CD8+ T-cells is reduced in COVID-19 patients since the beginning of SARS-CoV-2 infection and further decreased in severe cases. CD8+ T-cells often show signs of exhaustion, loss of T-cell functions and suppression in COVID-19 patients, suggesting that hampering CD8+ T-cells could be a way by which SARS-CoV-2 infection progresses. Importantly, the number of CD8+ T cells appears to re-increase in patients that are recovering from COVID-19, suggesting that CD8+ T-cells could be a key factor that determines whether our body can recover from the disease. We propose that therapies that boost CD8+ T cells could be effective in clearing SARS-CoV-2 infection in COVID-19. To test this, we will take advantage of the adenosine-mediated immunomodulation. Adenosine, an ATP metabolite that is produced during inflammation, hypoxia and in the tumor microenvironment, was found to suppress the immune response through activation of adenosine receptors present on immune cells. Small molecules antagonists that block one of these receptors, adenosine A2A receptor (A2AR) antagonists, are currently being studied to boost anti-cancer T-cell mediated immune responses. Our data show that treatment with an A2AR antagonist restores and stabilizes Notch1, a key pathway for T-cell functions, along with production of INF-gamma and Granzyme B and proliferation in CD8+ T-cells. As a proof of concept, our data indicates that treatment with an A2AR antagonist increases CD8+ T-cells anti-cancer response in tumor-derived organoids, suggesting that the treatment boosts CD8+ T-cells-mediated immune response. Ongoing work aims to test whether the A2AR antagonist treatment restores several parameters of T-cell function that are specifically modified in COVID-19. This analysis will help to predict the action of the A2AR antagonist on T-cells in vivo and we ultimately aim to test this treatment in a mouse model for COVID-19. Overall, our work could introduce a new paradigm and new therapies for COVID-19 and other infectious diseases.

Therapeutic potential of inosine pranobex in enhancing non-specific antiviral protection in patients with COVID-19

The defense mechanisms of the human body determine non-specific resistance of non-immune cells that comprise the majority of cells in the organism and are exposed to various environmental factors (such as radiation, pollutants, microbial infection), as well as innate and acquired immunity aimed at enhancing the response to external (and internal) stimuli. Inosine is one of the drugs that can strengthen the internal protective reserves of non-immune cells of the human body, primarily against various viruses. Inosine in the form of inosine pranobex is the main component of Groprinosin (Gedeon Richter Pharma LLC). It was shown that protective effect of inosine is attributed to its interaction with the surface adenosine A2A receptor from the family of G-protein-coupled receptors, with activation of the peroxisome proliferator-activated receptor gamma (PPAR-g). This results in inhibition of the mevalonate pathway of cholesterol synthesis and restriction of the viral life cycle of both enveloped (herpes viruses, hepatitis, dengue, mumps, influenza, Ebola, coronaviruses SARS-CoV, MERS-CoV, SARS-CoV-2) and non-enveloped (adenovirus, enterovirus, such as Coxsackie, rotavirus) viruses. Therefore, inosine can be included into the existing clinical protocols or used as an alternative to improve treatment efficacy. © 2021, Dynasty Publishing House. All rights reserved.

Relationship between adenosine A2a receptor polymorphism rs5751876 and fractional flow reserve during percutaneous coronary intervention.

Fractional flow reserve (FFR) assessed during adenosine-induced maximal hyperemia has emerged as a useful tool for the guidance of percutaneous coronary interventions (PCI). However, interindividual variability in the response to adenosine has been claimed as a major limitation to the use of adenosine for the measurement of FFR, carrying the risk of underestimating the severity of coronary stenoses, with potential negative prognostic consequences. Genetic variants of the adenosine receptor A2a (ADORA2A gene), located in the coronary circulation, have been involved in the modulation of the hyperemic response to adenosine. However, no study has so far evaluated the impact of the single nucleotide polymorphism rs5751876 of ADORA2A on the measurement of FFR in patients undergoing percutaneous coronary intervention that was, therefore, the aim of our study. We included patients undergoing coronary angiography and FFR assessment for intermediate (40-70%) coronary lesions. FFR measurement was performed by pressure-recording guidewire (Prime Wire, Volcano), after induction of hyperemia with intracoronary boli of adenosine (from 60 to 1440 µg, with dose doubling at each step). Restriction fragment length polymorphism (RFLP) analysis was performed to assess the presence of rs5751876 C>T polymorphism of ADORA2a receptor. We included 204 patients undergoing FFR measurement of 231 coronary lesions. A total of 134 patients carried the polymorphism (T allele), of whom 41 (30.6%) in homozygosis (T/T).Main clinical and angiographic features did not differ according to ADORA2A genotype. The rs5751876 C>T polymorphism did not affect mean FFR values (p = 0.91), the percentage of positive FFR (p = 0.54) and the duration of maximal hyperemia. However, the time to recovery to baseline FFR values was more prolonged among the T-allele carriers as compared to wild-type patients (p = 0.04). Based on these results, in patients with intermediate coronary stenoses undergoing FFR assessment with adenosine, the polymorphism rs5751876 of ADORA2A does not affect the peak hyperemic response to adenosine and the results of FFR. However, a more prolonged effect of adenosine was observed in T-carriers.