Potential Therapeutic Role of Purinergic Receptors in Cardiovascular Disease Mediated by SARS-CoV-2

Takotsubo syndrome as an outcome of the use of checkpoint inhibitor therapy in patients with COVID-19

Takotsubo Syndrome (TS) is a heart disease caused by extreme exposure of the body to physical or psychological stress. In the context of COVID-19, the virus can be a significant source of stress, with particular attention being paid to the cytokine storm as a cause of damage to the body. New research shows that the production of specific cytokines is linked to the activation of immune checkpoint proteins such as PD-1, PD-L1, and CTLA-4 on T cells. Although initially beneficial in combating infections, it can suppress defense and aid in disease progression. Therefore, checkpoint inhibitor therapy has been highlighted beyond oncological therapies, given its effectiveness in strengthening the immune system. However, this treatment can lead to excessive immune responses, inflammation, and stress on the heart, which can cause Takotsubo Syndrome in patients. Several studies investigate the direct link between this therapy and cardiac injuries in these patients, which can trigger TS. From this perspective, we must delve deeper into this treatment and consider its effects on the prognosis against SARS-CoV-2 infection.

The ATP-dependent Pathways and Human Diseases

Adenosine triphosphate (ATP) is one of the most important molecules of life, present both inside the cells and extracellularly. It is an essential building block for nucleic acids biosynthesis and crucial intracellular energy storage. However, one of the most interesting functions of ATP is the role of a signaling molecule. Numerous studies indicate the involvement of ATP-dependent pathways in maintaining the proper functioning of individual tissues and organs. Herein, the latest data indicating the ATP function in the network of intra- and extracellular signaling pathways including purinergic signaling, MAP kinase pathway, mTOR and calcium signaling are collected. The main ATP-dependent processes maintaining the proper functioning of the nervous, cardiovascular and immune systems, as well as skin and bones, are summarized. The disturbances in the ATP amount, its cellular localization, or interaction with target elements may induce pathological changes in signaling pathways leading to the development of serious diseases. The impact of an ATP imbalance on the development of dangerous health dysfunctions such as neurodegeneration diseases, cardiovascular diseases (CVDs), diabetes mellitus, obesity, cancers and immune pathogenesis are discussed here.

Inosine: A broad-spectrum anti-inflammatory against SARS-CoV-2 infection-induced acute lung injury via suppressing TBK1 phosphorylation

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced cytokine storms constitute the primary cause of coronavirus disease 19 (COVID-19) progression, severity, criticality, and death. Glucocorticoid and anti-cytokine therapies are frequently administered to treat COVID-19, but have limited clinical efficacy in severe and critical cases. Nevertheless, the weaknesses of these treatment modalities have prompted the development of anti-inflammatory therapy against this infection. We found that the broad-spectrum anti-inflammatory agent inosine downregulated proinflammatory interleukin (IL)-6, upregulated anti-inflammatory IL-10, and ameliorated acute inflammatory lung injury caused by multiple infectious agents. Inosine significantly improved survival in mice infected with SARS-CoV-2. It indirectly impeded TANK-binding kinase 1 (TBK1) phosphorylation by binding stimulator of interferon genes (STING) and glycogen synthase kinase-3β (GSK3β), inhibited the activation and nuclear translocation of the downstream transcription factors interferon regulatory factor (IRF3) and nuclear factor kappa B (NF-κB), and downregulated IL-6 in the sera and lung tissues of mice infected with lipopolysaccharide (LPS), H1N1, or SARS-CoV-2. Thus, inosine administration is feasible for clinical anti-inflammatory therapy against severe and critical COVID-19. Moreover, targeting TBK1 is a promising strategy for inhibiting cytokine storms and mitigating acute inflammatory lung injury induced by SARS-CoV-2 and other infectious agents.

The Potential of Purinergic Signaling to Thwart Viruses Including SARS-CoV-2

A long-shared evolutionary history is congruent with the multiple roles played by purinergic signaling in viral infection, replication and host responses that can assist or hinder viral functions. An overview of the involvement of purinergic signaling among a range of viruses is compared and contrasted with what is currently understood for SARS-CoV-2. In particular, we focus on the inflammatory and antiviral responses of infected cells mediated by purinergic receptor activation. Although there is considerable variation in a patient's response to SARS-CoV-2 infection, a principle immediate concern in Coronavirus disease (COVID-19) is the possibility of an aberrant inflammatory activation causing diffuse lung oedema and respiratory failure. We discuss the most promising potential interventions modulating purinergic signaling that may attenuate the more serious repercussions of SARS-CoV-2 infection and aspects of their implementation.

The Role of Purinergic Signaling in Heart Transplantation

Heart transplantation remains the optimal treatment option for patients with end-stage heart disease. Growing evidence demonstrates that purinergic signals mediated by purine nucleotides and nucleosides play vital roles in heart transplantation, especially in the era of ischemia-reperfusion injury (IRI) and allograft rejection. Purinergic signaling consists of extracellular nucleotides and nucleosides, ecto-enzymes, and cell surface receptors; it participates in the regulation of many physiological and pathological processes. During transplantation, excess adenosine triphosphate (ATP) levels are released from damaged cells, and driver detrimental inflammatory responses largely via purinergic P2 receptors. Ecto-nucleosidases sequentially dephosphorylate extracellular ATP to ADP, AMP, and finally adenosine. Adenosine exerts a cardioprotective effect by its anti-inflammatory, antiplatelet, and vasodilation properties. This review focused on the role of purinergic signaling in IRI and rejection after heart transplantation, as well as the clinical applications and prospects of purinergic signaling.

Novel possibility for cutaneous melanoma treatment by means of rosmarinic acid action on purinergic signaling

Cancer cases have increased significantly in Brazil and worldwide, with cutaneous melanoma (CM) being responsible for nearly 57,000 deaths in the world. Thus, this review article aims at exploring and proposed hypotheses with respect to the possibility that RA can be a promising and alternative compound to be used as an adjuvant in melanoma treatment, acting on purinergic signaling. The scarcity of articles evidencing the action of this compound in this signaling pathway requires further studies. Considering diverse evidence found in the literature, we hypothesize that RA can be an effective candidate for the treatment of CM acting as a modulating molecule of purinergic cellular pathway through P2X7 blocking, mitigating the Warburg effect, and as antagonic molecule of the P2Y12 receptor, reducing the formation of adhesive molecules that prevent adherence in tumor cells. In this way, our proposals for CM treatment based on targeting purinergic signaling permeate the integral practice, going from intracell to extracell. Undoubtedly, much is still to be discovered and elucidated about this promising compound, this paper being an interesting work baseline to support more research studies.

Purinergic signaling elements are correlated with coagulation players in peripheral blood and leukocyte samples from COVID-19 patients

For over a year, the coronavirus disease 2019 has been affecting the world population by causing severe tissue injuries and death in infected people. Adenosine triphosphate (ATP) and the nicotinamide adenine dinucleotide (NAD +) are two molecules that are released into the extracellular microenvironment after direct virus infection or cell death caused by hyper inflammation and coagulopathy. Also, these molecules are well known to participate in multiple pathways and have a pivotal role in the purinergic signaling pathway. Thus, using public datasets available on the Gene Expression Omnibus (GEO), we analyzed raw proteomics data acquired using mass spectrometry (the gold standard method) and raw genomics data from COVID-19 patient samples obtained by microarray. The data was analyzed using bioinformatics and statistical methods according to our objectives. Here, we compared the purinergic profile of the total leukocyte population and evaluated the levels of these soluble biomolecules in the blood, and their correlation with coagulation components in COVID-19 patients, in comparison to healthy people or non-COVID-19 patients. The blood metabolite analysis showed a stage-dependent inosine increase in COVID-19 patients, while the nucleotides ATP and ADP had positive correlations with fibrinogen and other coagulation proteins. Also, ATP, ADP, inosine, and hypoxanthine had positive and negative correlations with clinical features. Regarding leukocyte gene expression, COVID-19 patients showed an upregulation of the P2RX1, P2RX4, P2RX5, P2RX7, P2RY1, P2RY12, PANX1, ADORA2B, NLPR3, and F3 genes. Yet, the ectoenzymes of the canonical and non-canonical adenosinergic pathway (ENTPD1 and CD38) are upregulated, suggesting that adenosine is produced by both active adenosinergic pathways. Hence, approaches targeting these biomolecules or their specific purinoreceptors and ectoenzymes may attenuate the high inflammatory state and the coagulopathy seen in COVID-19 patients. KEY MESSAGES : Adenosinergic pathways are modulated on leukocytes from COVID-19 patients. Plasmatic inosine levels are increased in COVID-19 patients. ATP, ADP, AMP, hypoxanthine, and inosine are correlated with coagulation players. The nucleotides and nucleosides are correlated with patients' clinical features. The P2 receptors and ectoenzymes are correlated with Tissue factor in COVID-19.

Pannexin-1 channel opening is critical for COVID-19 pathogenesis

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapidly rampaged worldwide, causing a pandemic of coronavirus disease (COVID -19), but the biology of SARS-CoV-2 remains under investigation. We demonstrate that both SARS-CoV-2 spike protein and human coronavirus 229E (hCoV-229E) or its purified S protein, one of the main viruses responsible for the common cold, induce the transient opening of Pannexin-1 (Panx-1) channels in human lung epithelial cells. However, the Panx-1 channel opening induced by SARS-CoV-2 is greater and more prolonged than hCoV-229E/S protein, resulting in an enhanced ATP, PGE₂, and IL-1β release. Analysis of lung lavages and tissues indicate that Panx-1 mRNA expression is associated with increased ATP, PGE₂, and IL-1β levels. Panx-1 channel opening induced by SARS-CoV-2 spike protein is angiotensin-converting enzyme 2 (ACE-2), endocytosis, and furin dependent. Overall, we demonstrated that Panx-1 channel is a critical contributor to SARS-CoV-2 infection and should be considered as an alternative therapy.

Purinergic receptor ligands: the cytokine storm attenuators, potential therapeutic agents for the treatment of COVID-19

The coronavirus disease-19 (COVID-19), at first, was reported in Wuhan, China, and then rapidly became pandemic throughout the world. Cytokine storm syndrome (CSS) in COVID-19 patients is associated with high levels of cytokines and chemokines that cause multiple organ failure, systemic inflammation, and hemodynamic instabilities. Acute respiratory distress syndrome (ARDS), a common complication of COVID-19, is a consequence of cytokine storm. In this regard, several drugs have been being investigated to suppress this inflammatory condition. Purinergic signaling receptors comprising of P1 adenosine and P2 purinoceptors play a critical role in inflammation. Therefore, activation or inhibition of some subtypes of these kinds of receptors is most likely to be beneficial to attenuate cytokine storm. This article summarizes suggested therapeutic drugs with potential anti-inflammatory effects through purinergic receptors.

The role of P2X7 receptor in infection and metabolism: Based on inflammation and immunity

The P2X7 receptor (P2X7R) is a ligand-gated receptor belonging to the P2 receptor family. It is distributed in various tissues of the human body and is involved in regulating the physiological functions of tissues and cells to affect the occurrence and development of diseases. Unlike all other P2 receptors, the P2X7 receptor is mainly expressed in immune cells and can be activated not only by extracellular nucleotides but also by non-nucleotide substances which act as positive allosteric modulators. In this review, we comprehensively describe the role of the P2X7 receptor in infection and metabolism based on its role as an important regulator of inflammation and immunity, and briefly introduce the structure and general function of the P2X7 receptor. These provide a clear knowledge framework for the study of the P2X7 receptor in human health. Targeting the P2X7 receptor may be an effective method for the treatment of inflammatory and immune diseases. And its role in microbial infection and metabolism may be the main direction for in-depth research on the P2X7 receptor in the future.

Targeting purinergic receptors to suppress the cytokine storm induced by SARS-CoV-2 infection in pulmonary tissue

The etiological agent of coronavirus disease (COVID-19) is the new member of the Coronaviridae family, a severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2), responsible for the pandemic that is plaguing the world. The single-stranded RNA virus is capable of infecting the respiratory tract, by binding the spike (S) protein on its viral surface to receptors for the angiotensin II-converting enzyme (ACE2), highly expressed in the pulmonary tissue, enabling the interaction of the virus with alveolar epithelial cells promoting endocytosis and replication of viral material. The infection triggers the activation of the immune system, increased purinergic signaling, and the release of cytokines as a defense mechanism, but the response can become exaggerated and prompt the so-called “cytokine storm”, developing cases such as severe acute respiratory syndrome (SARS). This is characterized by fever, cough, and difficulty breathing, which can progress to pneumonia, failure of different organs and death. Thus, the present review aims to compile and correlate the mechanisms involved between the immune and purinergic systems with COVID-19, since the modulation of purinergic receptors, such as A2A, A2B, and P2X7 expressed by immune cells, seems to be effective as a promising therapy, to reduce the severity of the disease, as well as aid in the treatment of acute lung diseases and other cases of generalized inflammation.

SARS-CoV-2 Infection: New Molecular, Phylogenetic, and Pathogenetic Insights. Efficacy of Current Vaccines and the Potential Risk of Variants

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly discovered coronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic. COVID-19 has rapidly become a public health emergency of international concern. Although remarkable scientific achievements have been reached since the beginning of the pandemic, the knowledge behind this novel coronavirus, in terms of molecular and pathogenic characteristics and zoonotic potential, is still relatively limited. Today, there is a vaccine, or rather several vaccines, which, for the first time in the history of highly contagious infectious diseases that have plagued mankind, has been manufactured in just one year. Currently, four vaccines are licensed by regulatory agencies, and they use RNA or viral vector technologies. The positive effects of the vaccination campaign are being felt in many parts of the world, but the disappearance of this new infection is still far from being a reality, as it is also threatened by the presence of novel SARS-CoV-2 variants that could undermine the effectiveness of the vaccine, hampering the immunization control efforts. Indeed, the current findings indicate that SARS-CoV-2 is adapting to transmission in humans more efficiently, while further divergence from the initial archetype should be considered. In this review, we aimed to provide a collection of the current knowledge regarding the molecular, phylogenetic, and pathogenetic insights into SARS-CoV-2. The most recent findings obtained with respect to the impact of novel emerging SARS-CoV-2 variants as well as the development and implementation of vaccines are highlighted.

Hyperinflammation and airway surface liquid dehydration in cystic fibrosis: purinergic system as therapeutic target

OBJECTIVE AND DESIGN

The exacerbate inflammatory response contributes to the progressive loss of lung function in cystic fibrosis (CF), a genetic disease that affects the osmotic balance of mucus and mucociliary clearance, resulting in a microenvironment that favors infection and inflammation. The purinergic system, an extracellular signaling pathway characterized by nucleotides, enzymes and receptors, may have a protective role in the disease, through its action in airway surface liquid (ASL) and anti-inflammatory response.

MATERIALS AND METHODS

To make up this review, studies covering topics of CF, inflammation, ASL and purinergic system were selected from the main medical databases, such as Pubmed and ScienceDirect.

CONCLUSION

We propose several ways to modulate the purinergic system as a potential therapy for CF, like inhibition of P2X7, activation of P2Y2, A2A and A2B receptors and blocking of adenosine deaminase. Among them, we postulate that the most suitable strategy is to block the action of adenosine deaminase, which culminates in the increase of Ado levels that presents anti-inflammatory actions and improves mucociliary clearance. Furthermore, it is possible to maintain the physiological levels of ATP to control the hydration of ASL. These therapies could correct the main mechanisms that contribute to the progression of CF.

Role of the purinergic signaling network in lung ischemia-reperfusion injury

PURPOSE OF REVIEW

Primary graft dysfunction (PGD) is the leading cause of early mortality following lung transplantation and is typically caused by lung ischemia-reperfusion injury (IRI). Current management of PGD is largely supportive and there are no approved therapies to prevent lung IRI after transplantation. The purinergic signaling network plays an important role in this sterile inflammatory process, and pharmacologic manipulation of said network is a promising therapeutic strategy. This review will summarize recent findings in this area.

RECENT FINDINGS

In the past 18 months, our understanding of lung IRI has improved, and it is becoming clear that the purinergic signaling network plays a vital role. Recent works have identified critical components of the purinergic signaling network (Pannexin-1 channels, ectonucleotidases, purinergic P1 and P2 receptors) involved in inflammation in a number of pathologic states including lung IRI. In addition, a functionally-related calcium channel, the transient receptor potential vanilloid type 4 (TRPV4) channel, has recently been linked to purinergic signaling and has also been shown to mediate lung IRI.

SUMMARY

Agents targeting components of the purinergic signaling network are promising potential therapeutics to limit inflammation associated with lung IRI and thus decrease the risk of developing PGD.