Commentary: Phosphodiesterase 4 inhibitors as potential adjunct treatment targeting the cytokine storm in COVID-19

Integrin α5β1 contributes to cell fusion and inflammation mediated by SARS-CoV-2 spike via RGD-independent interaction

The Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus infects host cells by engaging its spike (S) protein with human ACE2 receptor. Recent studies suggest the involvement of integrins in SARS-CoV-2 infection through interaction with the S protein, but the underlying mechanism is not well understood. This study investigated the role of integrin α5β1, which recognizes the Arg-Gly-Asp (RGD) motif in its physiological ligands, in S-mediated virus entry and cell-cell fusion. Our results showed that α5β1 does not directly contribute to S-mediated cell entry, but it enhances S-mediated cell-cell fusion in collaboration with ACE2. This effect cannot be inhibited by the putative α5β1 inhibitor ATN-161 or the high-affinity RGD-mimetic inhibitor MK-0429 but requires the participation of α5 cytoplasmic tail (CT). We detected a direct interaction between α5β1 and the S protein, but this interaction does not rely on the RGD-containing receptor binding domain of the S1 subunit of the S protein. Instead, it involves the S2 subunit of the S protein and α5β1 homo-oligomerization. Furthermore, we found that the S protein induces inflammatory responses in human endothelial cells, characterized by NF-κB activation, gasdermin D cleavage, and increased secretion of proinflammatory cytokines IL-6 and IL-1β. These effects can be attenuated by the loss of α5 expression or inhibition of the α5 CT binding protein phosphodiesterase-4D (PDE4D), suggesting the involvement of α5 CT and PDE4D pathway. These findings provide molecular insights into the pathogenesis of SARS-CoV-2 mediated by a nonclassical RGD-independent ligand-binding and signaling function of integrin α5β1 and suggest potential targets for antiviral treatment.

PDE5 inhibitors: breaking new grounds in the treatment of COVID-19

INTRODUCTION

Despite the ever-increasing occurrences of the coronavirus disease (COVID-19) cases around the world, very few medications have been validated in the clinical trials to combat COVID-19. Although several vaccines have been developed in the past quarter, the time elapsed between deployment and administration remains a major impediment.

CONTENT

Repurposing of pre-approved drugs, such as phosphodiesterase 5 (PDE5) inhibitors, could be a game-changer while lessening the burden on the current healthcare system. Repurposing and developing phosphodiesterase 5 (PDE5) inhibitors could extrapolate their utility to combat the SARS-CoV-2 infection, and potentially aid in the management of the symptoms associated with its newer variants such as BF.7, BQ.1, BQ.1.1, XBB.1.5, and XBB.1.16.

SUMMARY

Administration of PDE5 inhibitors via the oral and intravenous route demonstrates other potential off-label benefits, including anti-apoptotic, anti-inflammatory, antioxidant, and immunomodulatory effects, by intercepting several pathways. These effects can not only be of clinical importance in mild-to-moderate, but also moderate-to-severe SARS-CoV-2 infections. This article explores the various mechanisms by which PDE5 inhibitors alleviates the symptoms associated with COVID-19 as well as well as highlights recent studies and findings.

OUTLOOK

These benefits of PDE5 inhibitors make it a potential drug in the physicians' armamentarium in alleviating symptoms associated with SARS-CoV-2 infection. However, adequate clinical studies must be instituted to eliminate any untoward adverse events.

Modulation of Human Dendritic Cell Functions by Phosphodiesterase-4 Inhibitors: Potential Relevance for the Treatment of Respiratory Diseases

Inhibitors of phosphodiesterase-4 (PDE4) are small-molecule drugs that, by increasing the intracellular levels of cAMP in immune cells, elicit a broad spectrum of anti-inflammatory effects. As such, PDE4 inhibitors are actively studied as therapeutic options in a variety of human diseases characterized by an underlying inflammatory pathogenesis. Dendritic cells (DCs) are checkpoints of the inflammatory and immune responses, being responsible for both activation and dampening depending on their activation status. This review shows evidence that PDE4 inhibitors modulate inflammatory DC activation by decreasing the secretion of inflammatory and Th1/Th17-polarizing cytokines, although preserving the expression of costimulatory molecules and the CD4+ T cell-activating potential. In addition, DCs activated in the presence of PDE4 inhibitors induce a preferential Th2 skewing of effector T cells, retain the secretion of Th2-attracting chemokines and increase the production of T cell regulatory mediators, such as IDO1, TSP-1, VEGF-A and Amphiregulin. Finally, PDE4 inhibitors selectively induce the expression of the surface molecule CD141/Thrombomodulin/BDCA-3. The result of such fine-tuning is immunomodulatory DCs that are distinct from those induced by classical anti-inflammatory drugs, such as corticosteroids. The possible implications for the treatment of respiratory disorders (such as COPD, asthma and COVID-19) by PDE4 inhibitors will be discussed.

PDE5 inhibitors: breaking new grounds in the treatment of COVID-19

INTRODUCTION

Despite the ever-increasing occurrences of the coronavirus disease (COVID-19) cases around the world, very few medications have been validated in the clinical trials to combat COVID-19. Although several vaccines have been developed in the past quarter, the time elapsed between deployment and administration remains a major impediment.

CONTENT

Repurposing of pre-approved drugs, such as phosphodiesterase 5 (PDE5) inhibitors, could be a game-changer while lessening the burden on the current healthcare system. Repurposing and developing phosphodiesterase 5 (PDE5) inhibitors could extrapolate their utility to combat the SARS-CoV-2 infection, and potentially aid in the management of the symptoms associated with its newer variants such as BF.7, BQ.1, BQ.1.1, XBB.1.5, and XBB.1.16.

SUMMARY

Administration of PDE5 inhibitors via the oral and intravenous route demonstrates other potential off-label benefits, including anti-apoptotic, anti-inflammatory, antioxidant, and immunomodulatory effects, by intercepting several pathways. These effects can not only be of clinical importance in mild-to-moderate, but also moderate-to-severe SARS-CoV-2 infections. This article explores the various mechanisms by which PDE5 inhibitors alleviates the symptoms associated with COVID-19 as well as well as highlights recent studies and findings.

OUTLOOK

These benefits of PDE5 inhibitors make it a potential drug in the physicians' armamentarium in alleviating symptoms associated with SARS-CoV-2 infection. However, adequate clinical studies must be instituted to eliminate any untoward adverse events.

Dermatology Publications on COVID-19 during the First Pandemic Year: Creativity or Opportunism?

Introduction: Dermatologists had to face several challenges during the COVID-19 pandemic. In this scenario, a large amount of data has been produced and published. Objectives: We present a literature analysis of publications on COVID-19 in the dermatology field in the first year of the pandemic. Methods: The research was carried out by searching the PubMed database using keywords related to “COVID-19” combined with the keyword “Dermatology” in the “affiliation” search field and collecting articles published from February 2020 to December 2020. Results: A total of 816 publications from 57 countries were retrieved. Overall, publications increased notably along the timespan considered in this study and appeared to be closely linked to pandemic progression in different countries. In addition, article types (i.e., commentaries, case reports, original research) appeared to be strictly influenced by the pandemic’s progression. However, the number and category of these publications may raise questions regarding the scientific relevance of the messages reported. Conclusions: Our analysis provides a descriptive quantitative analysis and suggests that publications do not always respond to real scientific needs but are sometimes linked to a need/opportunity for publication.

The Complexity and Multiplicity of the Specific cAMP Phosphodiesterase Family: PDE4, Open New Adapted Therapeutic Approaches

Cyclic nucleotides (cAMP, cGMP) play a major role in normal and pathologic signaling. Beyond receptors, cyclic nucleotide phosphodiesterases; (PDEs) rapidly convert the cyclic nucleotide in its respective 5′-nucleotide to control intracellular cAMP and/or cGMP levels to maintain a normal physiological state. However, in many pathologies, dysregulations of various PDEs (PDE1-PDE11) contribute mainly to organs and tissue failures related to uncontrolled phosphorylation cascade. Among these, PDE4 represents the greatest family, since it is constituted by 4 genes with multiple variants differently distributed at tissue, cellular and subcellular levels, allowing different fine-tuned regulations. Since the 1980s, pharmaceutical companies have developed PDE4 inhibitors (PDE4-I) to overcome cardiovascular diseases. Since, they have encountered many undesired problems, (emesis), they focused their research on other PDEs. Today, increases in the knowledge of complex PDE4 regulations in various tissues and pathologies, and the evolution in drug design, resulted in a renewal of PDE4-I development. The present review describes the recent PDE4-I development targeting cardiovascular diseases, obesity, diabetes, ulcerative colitis, and Crohn’s disease, malignancies, fatty liver disease, osteoporosis, depression, as well as COVID-19. Today, the direct therapeutic approach of PDE4 is extended by developing allosteric inhibitors and protein/protein interactions allowing to act on the PDE interactome.

A chromatin remodeling checkpoint of diet-induced macrophage activation in adipose tissue

The interplay between the environment and the immune cells is linked to metabolic homeostasis under physiologic and pathophysiologic conditions. Diabetes mellitus type 2 (T2D) is considered an immune-related inflammatory disorder, in which the adipose tissue macrophages (ATMs) are key players orchestrating metabolic chronic meta-inflammation and contributing to the pathogenesis of metabolic disease. However, the molecular regulators that integrate the environmental signals to control ATM activation and adipose inflammation during obesity and T2D remain unclear. Epigenetic mechanisms constitute important parameters in metabolic homeostasis, obesity and T2D via the integration of the environmental factors to the transcriptional regulation of gene programs. In a very recent study published in Diabetes by Kong et al., BAF60a has been identified as a key chromatin remodeling checkpoint factor that associates obesity-associated stress signals with meta-inflammation and systemic homeostasis. Furthermore, this work uncovers Atf3 as an important downstream effector in BAF60a-mediated chromatin remodeling and transcriptional reprogramming of macrophage activation in adipose tissue. The findings of this research may contribute to the development of new therapeutic approaches for obesity-induced metabolic inflammation and associated metabolic disorders.

Of mice and men: Considerations on adipose tissue physiology in animal models of obesity and human studies

The ever-increasing burden of obesity demands a better pathophysiological understanding, especially regarding adipose tissue pathophysiology. Animal models of obesity are of great importance in investigating potential mechanisms and implications of obesity. Many issues should be considered while interpreting the preclinical results as anatomical and pathophysiological differences exist among species. Importantly, the natural history of obesity development differs considerably. An important example of conflicting results among preclinical models and human physiological studies is that of adipose tissue oxygenation, where rodent models almost unanimously have shown the presence of hypoxia in the adipose tissue of obese animals while human studies have yielded conflicting results to date. Other issues which require further clarification before generalizing preclinical data in humans include adipose tissue browning, endocrine function and fibrosis. The aim of this mini-review is to synopsize similarities and differences between rodent models and humans, which should be taken into consideration in obesity studies.

Breakthrough infections after COVID-19 vaccination: Insights, perspectives and challenges

Vaccination programs against SARS-CoV-2 constitute the mainstay of public health interventions against the global COVID-19 pandemic. Currently available vaccines have shown 90% or better rates of protection against severe disease and mortality. Barely a year after vaccines became available, the Omicron variant and its unprecedented speed of transmission has posed a new challenge. Overall, Omicron presents increased immune escape, transmissibility, and decreased pathogenicity. Vaccines do not offer a full protection against SARS-CoV-2 acquisition, since "breakthrough" infections may occur in fully vaccinated individuals, who may in turn spread the virus to others. Breakthrough infections may be causally related to the viral profile (viral variant and load, incubation period, transmissibility, pathogenicity, immune evasion), immunity characteristics (mucosal versus systemic immunity, duration of immunity, etc.), host determinants (age, comorbidities, immune status, immunosuppressive drugs) and vaccination properties (platform, antigen dose, dose number, dose interval, route of administration). Determining the rate of breakthrough infections may be challenging and necessitates the conduction of population-based studies regarding vaccine effectiveness as well as neutralizing antibody testing, a surrogate of immune protection. In this review, we analyze the causes of breakthrough infections, their clinical consequences (severity of infection and transmission), methods of determining their incidence as well as challenges and perspectives. Long COVID as well as multi-inflammatory syndrome in adolescents may be significantly reduced in breakthrough infections. The need for universal pancoranavirus vaccines that would aim at protecting against a plethora of SARS-CoV-2 variants as well as emerging variants is discussed. Finally, novel vaccine strategies, such as nasal vaccines, may confer robust mucosal and systemic protection, reducing efficiently transmission.

Identification of novel off targets of baricitinib and tofacitinib by machine learning with a focus on thrombosis and viral infection

As there are no clear on-target mechanisms that explain the increased risk for thrombosis and viral infection or reactivation associated with JAK inhibitors, the observed elevated risk may be a result of an off-target effect. Computational approaches combined with in vitro studies can be used to predict and validate the potential for an approved drug to interact with additional (often unwanted) targets and identify potential safety-related concerns. Potential off-targets of the JAK inhibitors baricitinib and tofacitinib were identified using two established machine learning approaches based on ligand similarity. The identified targets related to thrombosis or viral infection/reactivation were subsequently validated using in vitro assays. Inhibitory activity was identified for four drug-target pairs (PDE10A [baricitinib], TRPM6 [tofacitinib], PKN2 [baricitinib, tofacitinib]). Previously unknown off-target interactions of the two JAK inhibitors were identified. As the proposed pharmacological effects of these interactions include attenuation of pulmonary vascular remodeling, modulation of HCV response, and hypomagnesemia, the newly identified off-target interactions cannot explain an increased risk of thrombosis or viral infection/reactivation. While further evidence is required to explain both the elevated thrombosis and viral infection/reactivation risk, our results add to the evidence that these JAK inhibitors are promiscuous binders and highlight the potential for repurposing.

Inhibitory effect of roflumilast on experimental periodontitis

BACKGROUND

Phosphodiesterase-4 (PDE4) has been identified as a valid therapeutic target in several inflammatory diseases. In this study, we assessed PDE4 in gingival tissue from patients with chronic periodontitis and evaluated the therapeutic effects of the PDE4 inhibitor, roflumilast, in an experimental rat model of periodontitis.

METHODS

Gingival tissue specimens from 20 healthy subjects and 20 patients with periodontitis were collected, and the mRNA expression levels of PDE4, interleukin (IL)-1β, and IL-6 were assessed. Ninety rats were divided randomly into three groups (30 per group): non-ligature group, ligature-induced periodontitis group (L), and ligature-induced periodontitis with roflumilast administered group (5 mg/kg/d) (L+R). Rats were euthanized on days 3, 8, and 14. Alveolar bone resorption was analyzed using microcomputed tomography. Inflammation and osteoclast number were analyzed histologically. Finally, the mRNA expression levels of PDE-4, IL-1β, IL-6, tumor necrosis factor (TNF)-α, and nuclear factor kappa B (NF-κB) were assessed in the rat gingival tissue.

RESULTS

The mRNA expression levels of PDE4, IL-1β, and IL-6 in the gingiva were significantly higher in patients with periodontitis compared with healthy individuals (P <0.05). Alveolar bone loss, degree of inflammation, number of TRAP-positive multinucleated osteoclasts, and mRNA expression levels of IL-1β, IL-6, TNF-α, NF-κB, and PDE4 in the L+R group were significantly lower than those in the L group (P <0.05).

CONCLUSIONS

PDE4 expression was increased in the gingiva of patients with periodontitis. Roflumilast may decrease alveolar bone loss and the expression of inflammatory cytokines in rats with ligature-induced periodontitis.

Apremilast Improves Endothelial Glycocalyx Integrity, Vascular and Left Ventricular Myocardial Function in Psoriasis

The phosphodiesterase 4 inhibitor apremilast is used for the treatment of psoriasis. We investigated the effects of apremilast on endothelial glycocalyx, vascular and left ventricular (LV) myocardial function in psoriasis. One hundred and fifty psoriatic patients were randomized to apremilast (n = 50), anti-tumor necrosis factor-α (etanercept; n = 50), or cyclosporine (n = 50). At baseline and 4 months post-treatment, we measured: (1) Perfused boundary region (PBR), a marker of glycocalyx integrity, in sublingual microvessels with diameter 5–25 μm using a Sidestream Dark Field camera (GlycoCheck). Increased PBR indicates damaged glycocalyx. Functional microvascular density, an index of microvascular perfusion, was also measured. (2) Pulse wave velocity (PWV-Complior) and (3) LV global longitudinal strain (GLS) using speckle-tracking echocardiography. Compared with baseline, PBR5–25 μm decreased only after apremilast (−12% at 4 months, p < 0.05) whereas no significant changes in PBR5–25 μm were observed after etanercept or cyclosporine treatment. Compared with etanercept and cyclosporine, apremilast resulted in a greater increase of functional microvascular density (+14% versus +1% versus −1%) and in a higher reduction of PWV. Apremilast showed a greater increase of GLS (+13.5% versus +7% versus +2%) than etanercept and cyclosporine (p < 0.05). In conclusion, apremilast restores glycocalyx integrity and confers a greater improvement of vascular and myocardial function compared with etanercept or cyclosporine after 4 months.

The PDE4 Inhibitor Tanimilast Blunts Proinflammatory Dendritic Cell Activation by SARS-CoV-2 ssRNAs

Phosphodiesterase 4 (PDE4) inhibitors are immunomodulatory drugs approved to treat diseases associated with chronic inflammatory conditions, such as COPD, psoriasis and atopic dermatitis. Tanimilast (international non-proprietary name of CHF6001) is a novel, potent and selective inhaled PDE4 inhibitor in advanced clinical development for the treatment of COPD. To begin testing its potential in limiting hyperinflammation and immune dysregulation associated to SARS-CoV-2 infection, we took advantage of an in vitro model of dendritic cell (DC) activation by SARS-CoV-2 genomic ssRNA (SCV2-RNA). In this context, Tanimilast decreased the release of pro-inflammatory cytokines (TNF-α and IL-6), chemokines (CCL3, CXCL9, and CXCL10) and of Th1-polarizing cytokines (IL-12, type I IFNs). In contrast to β-methasone, a reference steroid anti-inflammatory drug, Tanimilast did not impair the acquisition of the maturation markers CD83, CD86 and MHC-II, nor that of the lymph node homing receptor CCR7. Consistent with this, Tanimilast did not reduce the capability of SCV2-RNA-stimulated DCs to activate CD4⁺ T cells but skewed their polarization towards a Th2 phenotype. Both Tanimilast and β-methasone blocked the increase of MHC-I molecules in SCV2-RNA-activated DCs and restrained the proliferation and activation of cytotoxic CD8⁺ T cells. Our results indicate that Tanimilast can modulate the SCV2-RNA-induced pro-inflammatory and Th1-polarizing potential of DCs, crucial regulators of both the inflammatory and immune response. Given also the remarkable safety demonstrated by Tanimilast, up to now, in clinical studies, we propose this inhaled PDE4 inhibitor as a promising immunomodulatory drug in the scenario of COVID-19.

Antirheumatic Drugs against COVID-19 from the Perspective of Rheumatologists

Coronavirus disease 2019 (COVID-19) remains a global threat to humanity. Its pathogenesis and different phases of disease progression are being elucidated under the pandemic. Active viral replication activates various immune cells and produces large amounts of inflammatory cytokines, which leads to the cytokine storm, a major cause of patient death. Therefore, viral inhibition is expected to be the most effective early in the course of the disease, while immunosuppressive treatment may be useful in the later stages to prevent disease progression. Based on the pathophysiology of rheumatic diseases, various immunomodulatory and immunosuppressive drugs are used for the diseases. Due to their mechanism of action, the antirheumatic drugs, including hydroxychloroquine, chloroquine, colchicine, calcineurin inhibitors (e.g., cyclosporine A and tacrolimus), glucocorticoids, cytokines inhibitors, such as anti-tumor necrosis factor-α (e.g., infliximab), anti-interleukin (IL)-6 (e.g., tocilizumab, sarilumab, and siltuximab), anti-IL-1 (e.g., anakinra and canakinumab) and Janus kinase inhibitors (e.g., baricitinib and tofacitinib), cytotoxic T lymphocyte-associated antigen 4 blockade agents (e.g., abatacept), and phosphodiesterase 4 inhibitors (e.g., apremilast), have been tried as a treatment for COVID-19. In this review, we discuss the mechanisms of action and clinical impact of these agents in the management of COVID-19.

Charting the Unknown Association of COVID-19 with Thyroid Cancer, Focusing on Differentiated Thyroid Cancer: A Call for Caution

BACKGROUND

Conceived of as the "silver lining" of the dark cloud of the coronavirus disease 2019 (COVID-19) pandemic, lessons taught by this catastrophe should be leveraged by medical authorities and policy makers to optimize health care globally. A major lesson is that resilient health systems should absorb sudden shocks incited by overwhelming health emergencies without compromising the continuum of care of chronic diseases, especially of cancer.

METHODS

The present review dissects the association between COVID-19 and thyroid cancer (TC), especially with differentiated TC (DTC), focusing on available data, knowledge gaps, current challenges, and future perspectives.

RESULTS

Obesity has been incriminated in terms of both COVID-19 severity and a rising incidence of TC, especially of DTC. The current conceptualization of the pathophysiological landscape of COVID-19-(D)TC association implicates an interplay between obesity, inflammation, immunity, and oxidative stress. Whether COVID-19 could aggravate the health burden posed by (D)TC or vice versa has yet to be clarified. Improved understanding and harnessing of the pathophysiological landscape of the COVID-19-(D)TC association will empower a mechanism-guided, safe, evidence-based, and risk-stratified management of (D)TC in the COVID-19 era and beyond.

CONCLUSION

A multidisciplinary patient-centered decision-making will ensure high-quality (D)TC care for patients, with or without COVID-19.

PdCl2-catalyzed synthesis of a new class of isocoumarin derivatives containing aminosulfonyl / aminocarboxamide moiety: First identification of a isocoumarin based PDE4 inhibitor

While anti-inflammatory properties of isocoumarins are known their PDE4 inhibitory potential was not explored previously. In our effort the non-PDE4 inhibitor isocoumarins were transformed into the promising inhibitors via introducing an aminosulfonyl/aminocarboxamide moiety to the C-3 benzene ring attached to the isocoumarin framework. This new class of isocoumarins were synthesized via a PdCl2-catalyzed construction of the 4-allyl substituted 3-aryl isocoumarin ring starting from the appropriate 2-alkynyl benzamide derivative. Several compounds showed good inhibition of PDE4B in vitro and the SAR indicated superiority of aminosulfonamide moiety over aminocarboxamide in terms of PDE4B inhibition. Two compounds 3q and 3u with PDE4B IC50 = 0.43 ± 0.11 and 0.54 ± 0.19 μM and ≥ 2-fold selectivity over PDE4D emerged as initial hits. The participation of aminosulfonamide moiety in PDE4B inhibition and the reason for selectivity though moderate shown by 3q and 3u was revealed by the in silico docking studies. In view of potential usefulness of moderately selective PDE4B inhibitors the compound 3u (that showed PDE4 selectivity over other PDEs) was further evaluated in adjuvant induced arthritic rats. At an intraperitoneal dose of 30 mg/kg the compound showed a significant reduction in paw swelling (in a dose dependent manner), inflammation and pannus formation (in the knee joints) as well as pro-inflammatory gene expression/mRNA levels and increase in body weight. Moreover, besides its TNF-α inhibition and no significant toxicity in an MTT assay the compound did not show any adverse effects in a thorough toxicity studies e.g. teratogenicity, hepatotoxicity, cardiotoxicity and apoptosis in zebrafish. Thus, the isocoumarin 3u emerged as a new, safe and moderately selective PDE4B inhibitor could be useful for inflammatory diseases possibly including COVID-19.

Pd-catalysed general access to 7-membered N/O-heterocyclic compounds as potential agents against inflammation

A Pd-catalysed regioselective synthesis of 4,5-disubstituted 7-membered N/O-heterocycles was achieved via the 7-endo-dig cyclization followed by C-C bond formation of 2-(1-alkynyl)phenylacetamide. The ligand/additive free cascade reaction proceeded in the presence of PdCl₂ in aqueous MeCN when the separate and individual use of methyl vinyl ketone and allyl bromide generally afforded an O- and N-heterocycle, respectively. The pharmacological assay was performed to identify the first example of a 1H-benzo[d]azepin-2(3H)-one based novel inhibitor of PDE4B.

Understanding the Co-Epidemic of Obesity and COVID-19: Current Evidence, Comparison with Previous Epidemics, Mechanisms, and Preventive and Therapeutic Perspectives

PURPOSE OF REVIEW

A growing body of evidence suggests that obesity and increased visceral adiposity are strongly and independently linked to adverse outcomes and death due to COVID-19. This review summarizes current epidemiologic data, highlights pathogenetic mechanisms on the association between excess body weight and COVID-19, compares data from previous pandemics, discusses why COVID-19 challenges the "obesity paradox," and presents implications in prevention and treatment as well as future perspectives.

RECENT FINDINGS

Data from meta-analyses based on recent observational studies have indicated that obesity increases the risks of infection from SARS-CoV-2, severe infection and hospitalization, admission to the ICU and need of invasive mechanical ventilation (IMV), and the risk of mortality, particularly in severe obesity. The risks of IMV and mortality associated with obesity are accentuated in younger individuals (age ≤ 50 years old). The meta-inflammation in obesity intersects with and exacerbates underlying pathogenetic mechanisms in COVID-19 through the following mechanisms and factors: (i) impaired innate and adaptive immune responses; (ii) chronic inflammation and oxidative stress; (iii) endothelial dysfunction, hypercoagulability, and aberrant activation of the complement; (iv) overactivation of the renin-angiotensin-aldosterone system; (v) overexpression of the angiotensin-converting enzyme 2 receptor in the adipose tissue; (vi) associated cardiometabolic comorbidities; (vii) vitamin D deficiency; (viii) gut dysbiosis; and (ix) mechanical and psychological issues. Mechanistic and large epidemiologic studies using big data sources with omics data exploring genetic determinants of risk and disease severity as well as large randomized controlled trials (RCTs) are necessary to shed light on the pathways connecting chronic subclinical inflammation/meta-inflammation with adverse COVID-19 outcomes and establish the ideal preventive and therapeutic approaches for patients with obesity.

CuCl2-catalyzed inexpensive, faster and ligand/additive free synthesis of isoquinolin-1(2H)-one derivatives via the coupling-cyclization strategy: Evaluation of a new class of compounds as potential PDE4 inhibitors

In spite of possessing a wide range of pharmacological properties the anti-inflammatory activities of isoquinolin-1(2H)-ones were rarely known or explored earlier. PDE4 inhibitors on the other hand in addition to their usefulness in treating inflammatory diseases have been suggested to attenuate the cytokine storm in COVID-19 especially TNF-α. In our effort, a new class of isoquinolin-1(2H)-ones derivatives containing an aminosulfonyl moiety were designed and explored as potential inhibitors of PDE4. Accordingly, for the first time a CuCl₂-catalyzed inexpensive, faster and ligand/additive free approach has been developed for the synthesis of these predesigned isoquinolin-1(2H)-one derivatives via the coupling-cyclization strategy. Thus, the CuCl₂-catalyzed reaction of 2-iodobenzamides with appropriate terminal alkynes proceeded with high chemo and regioselectivity affording the desired compounds in 77-84% yield within 1-1.5 h. The methodology also afforded simpler isoquinolin-1(2H)-ones devoid of aminosulfonyl moiety showing a broader generality and scope of this approach. Several of the synthesized compounds especially 3c, 3k and 3s showed impressive inhibition (83-90%) of PDE4B when tested at 10 µM in vitro whereas compounds devoid of aminosulfonyl moiety was found to be less active. In spite of high inhibition showed at 10 µM these compounds did not show proper concertation dependent inhibition below 1 µM that was reflected in their IC₅₀ values e.g. 2.43 ± 0.32, 3.26 ± 0.24 and 3.63 ± 0.80 µM for 3k, 3o and 3s respectively. The anti-inflammatory potential of these compounds was indicated by their TNF-α inhibition (60-50% at 10 µM). The in silico docking studies of these molecules suggested good interactions with PDE4B and selective inhibition of PDE4B by 3k over PDE4D that was supported by in vitro assay results. These observations together with the favorable ADME and safety predicted for 3kin silico not only suggested 3k as an interesting hit molecule for further studies but also reveal the first example of isoquinolin-1(2H)-one based inhibitor of PDE4B.

Host metabolic reprogramming in response to SARS-CoV-2 infection: A systems biology approach

Understanding the pathogenesis of SARS-CoV-2 is essential for developing effective treatment strategies. Viruses hijack the host metabolism to redirect the resources for their replication and survival. The influence of SARS-CoV-2 on host metabolism is yet to be fully understood. In this study, we analyzed the transcriptomic data obtained from different human respiratory cell lines and patient samples (nasopharyngeal swab, peripheral blood mononuclear cells, lung biopsy, bronchoalveolar lavage fluid) to understand metabolic alterations in response to SARS-CoV-2 infection. We explored the expression pattern of metabolic genes in the comprehensive genome-scale network model of human metabolism, Recon3D, to extract key metabolic genes, pathways, and reporter metabolites under each SARS-CoV-2-infected condition. A SARS-CoV-2 core metabolic interactome was constructed for network-based drug repurposing. Our analysis revealed the host-dependent dysregulation of glycolysis, mitochondrial metabolism, amino acid metabolism, nucleotide metabolism, glutathione metabolism, polyamine synthesis, and lipid metabolism. We observed different pro- and antiviral metabolic changes and generated hypotheses on how the host metabolism can be targeted for reducing viral titers and immunomodulation. These findings warrant further exploration with more samples and in vitro studies to test predictions.

Gut probiotic Lactobacillus rhamnosus attenuates PDE4B-mediated interleukin-6 induced by SARS-CoV-2 membrane glycoprotein

Membrane glycoprotein is the most abundant protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but its role in coronavirus disease 2019 (COVID-19) has not been fully characterized. Mice intranasally inoculated with membrane glycoprotein substantially increased the interleukin (IL)-6, a hallmark of the cytokine storm, in bronchoalveolar lavage fluid (BALF), compared to mice inoculated with green fluorescent protein (GFP). The high level of IL-6 induced by membrane glycoprotein was significantly diminished in phosphodiesterase 4 (PDE4B) knockout mice, demonstrating the essential role of PDE4B in IL-6 signaling. Mycelium fermentation of Lactobacillus rhamnosus (L. rhamnosus) EH8 strain yielded butyric acid, which can down-regulate the PDE4B expression and IL-6 secretion in macrophages. Feeding mice with mycelia increased the relative abundance of commensal L. rhamnosus. Two-week supplementation of mice with L. rhamnosus plus mycelia considerably decreased membrane glycoprotein-induced PDE4B expression and IL-6 secretion. The probiotic activity of L. rhamnosus plus mycelia against membrane glycoprotein was abolished in mice treated with GLPG-0974, an antagonist of free fatty acid receptor 2 (Ffar2). Activation of Ffar2 in the gut-lung axis for down-regulation of the PDE4B-IL-6 signalling may provide targets for development of modalities including probiotics for treatment of the cytokine storm in COVID-19.

Anti-viral treatment for SARS-CoV-2 infection: A race against time amidst the ongoing pandemic

Remdesivir (GS-5734), a drug initially developed to treat hepatitis C and Ebola virus disease, was the first approved treatment for severe coronavirus disease 2019 (COVID-19). However, apart from remdesivir, there is a paucity of other specific anti-viral agents against SARS-CoV-2 infection. In 2017, researchers had documented the anti-coronavirus potential of remdesivir in animal models. At the same time, trials performed during two Ebola outbreaks in Africa showed that the drug was safe. Although vaccines against SARS-CoV-2 infection have emerged at an enormously high speed, equivalent results from efforts towards the development of anti-viral drugs, which could have played a truly life-saving role in the current stage of the pandemic, have been stagnating. In this review, we will focus on the current treatment options for COVID-19 which mainly consist of repurposed agents or treatments conferring passive immunity (convalescent plasma or monoclonal antibodies). Additionally, potential specific anti-viral therapies under development will be reviewed, such as the decoy miniprotein CTC-445.2d, protease inhibitors, mainly against the Main protein Mpro, nucleoside analogs, such as molnupiravir and compounds blocking the replication transcription complex proteins, such as zotatifin and plitidepsin. These anti-viral agents seem to be very promising but still require meticulous clinical trial testing in order to establish their efficacy and safety. The continuous emergence of viral variants may pose a real challenge to the scientific community towards that end. In this context, the advent of nanobodies together with the potential administration of a combination of anti-viral drugs could serve as useful tools in the armamentarium against COVID-19.

Vagus Nerve Stimulation: A Potential Adjunct Therapy for COVID-19

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19) through excessive end organ inflammation. Despite improved understanding of the pathophysiology, management, and the great efforts worldwide to produce effective drugs, death rates of COVID-19 patients remain unacceptably high, and effective treatment is unfortunately lacking. Pharmacological strategies aimed at modulating inflammation in COVID-19 are being evaluated worldwide. Several drug therapies targeting this excessive inflammation, such as tocilizumab, an interleukin (IL)-6 inhibitor, corticosteroids, programmed cell death protein (PD)-1/PD-L1 checkpoint inhibition, cytokine-adsorption devices, and intravenous immunoglobulin have been identified as potentially useful and reliable approaches to counteract the cytokine storm. However, little attention is currently paid for non-drug therapeutic strategies targeting inflammatory and immunological processes that may be useful for reducing COVID-19-induced complications and improving patient outcome. Vagus nerve stimulation attenuates inflammation both in experimental models and preliminary data in human. Modulating the activity of cholinergic anti-inflammatory pathways (CAPs) described by the group of KJ Tracey has indeed become an important target of therapeutic research strategies for inflammatory diseases and sepsis. Non-invasive transcutaneous vagal nerve stimulation (t-VNS), as a non-pharmacological adjuvant, may help reduce the burden of COVID-19 and deserve to be investigated. VNS as an adjunct therapy in COVID-19 patients should be investigated in clinical trials. Two clinical trials on this topic are currently underway (NCT04382391 and NCT04368156). The results of these trials will be informative, but additional larger studies are needed.

Pyrrolo[2,3-b]quinoxalines in attenuating cytokine storm in COVID-19: their sonochemical synthesis and in silico / in vitro assessment

In view of the recent global pandemic caused by COVID-19 intense efforts have been devoted worldwide towards the development of an effective treatment for this disease. Recently, PDE4 inhibitors have been suggested to attenuate the cytokine storm in COVID-19 especially tumour necrosis factor alpha (TNF-α). In our effort we have explored the 2-substituted pyrrolo[2,3-b]quinoxalines for this purpose because of their potential inhibitory properties of PDE-4 / TNF-α. Moreover, several of these compounds appeared to be promising in silico when assessed for their binding affinities via docking into the N-terminal RNA-binding domain (NTD) of N-protein of SARS-CoV-2. A rapid and one-pot synthesis of this class of molecules was achieved via the Cu-catalyzed coupling-cyclization-desulfinylation of 3-alkynyl-2-chloroquinoxalines with t-butyl sulfinamide as the ammonia surrogate under ultrasound irradiation. Most of these compounds showed good to significant inhibition of TNF-α in vitro establishing a SAR (Structure Activity Relationship) within the series. One compound e.g. 3i was identified as a promising hit for which the desirable ADME and acceptable toxicity profile was predicted in silico.

The neuropsychiatric manifestations of COVID-19: Interactions with psychiatric illness and pharmacological treatment

The recent outbreak of the corona virus disease (COVID-19) has had major global impact. The relationship between severe acute respiratory syndrome coronavirus (SARS-CoV-2) infection and psychiatric diseases is of great concern, with an evident link between corona virus infections and various central and peripheral nervous system manifestations. Unmitigated neuro-inflammation has been noted to underlie not only the severe respiratory complications of the disease but is also present in a range of neuro-psychiatric illnesses. Several neurological and psychiatric disorders are characterized by immune-inflammatory states, while treatments for these disorders have distinct anti-inflammatory properties and effects. With inflammation being a common contributing factor in SARS-CoV-2, as well as psychiatric disorders, treatment of either condition may affect disease progression of the other or alter response to pharmacological treatment. In this review, we elucidate how viral infections could affect pre-existing psychiatric conditions and how pharmacological treatments of these conditions may affect overall progress and outcome in the treatment of SARS-CoV-2. We address whether any treatment-induced benefits and potential adverse effects may ultimately affect the overall treatment approach, considering the underlying dysregulated neuro-inflammatory processes and potential drug interactions. Finally, we suggest adjunctive treatment options for SARS-CoV-2-associated neuro-psychiatric symptoms.

Drug Repurposing in the COVID-19 Era: Insights from Case Studies Showing Pharmaceutical Peculiarities

COVID-19 may lead to severe respiratory distress syndrome and high risk of death in some patients. So far (January 2021), only the antiviral remdesivir has been approved, although no significant benefits in terms of mortality and clinical improvement were recently reported. In a setting where effective and safe treatments for COVID-19 are urgently needed, drug repurposing may take advantage of the fact that the safety profile of an agent is already well known and allows rapid investigation of the efficacy of potential treatments, at lower costs and with reduced risk of failure. Furthermore, novel pharmaceutical formulations of older agents (e.g., aerosolized administration of chloroquine/hydroxychloroquine, remdesivir, heparin, pirfenidone) have been tested in order to increase pulmonary delivery and/or antiviral effects of potentially active drugs, thus overcoming pharmacokinetic issues. In our review, we will highlight the importance of the drug repurposing strategy in the context of COVID-19, including regulatory and ethical aspects, with a specific focus on novel pharmaceutical formulations and routes of administration.

Multifunctional lipid-based nanocarriers with antibacterial and anti-inflammatory activities for treating MRSA bacteremia in mice

Background

Bacteremia-induced sepsis is a leading cause of mortality in intensive care units. To control a bacterial infection, an immune response is required, but this response might contribute to organ failure. Kidneys are one of the main organs affected by bacteremia. Combination therapies with antibacterial and anti-inflammatory effects may be beneficial in treating bacteremia. This study aimed to develop nanostructured lipid carriers (NLCs) loaded with ciprofloxacin and rolipram that exert a combination of anti-methicillin-resistant Staphylococcus aureus (MRSA) and anti-inflammatory effects. Retinol was incorporated into the nanoparticles to transport retinol-binding protein 4 (RBP4) to the kidneys, which abundantly express RBP receptors. The NLCs were fabricated by high-shear homogenization and sonication, and neutrophils were used as a model to assess their anti-inflammatory effects. Mice were injected with MRSA to establish a model of bacteremia with organ injury.

Results

The mean nanoparticle size and zeta potential of the NLCs were 171 nm and − 39 mV, respectively. Ciprofloxacin (0.05%, w/v) and rolipram (0.02%) achieved encapsulation percentages of 88% and 96%, respectively, in the nanosystems. The minimum bactericidal concentration of free ciprofloxacin against MRSA increased from 1.95 to 15.63 µg/ml when combined with rolipram, indicating a possible drug-drug interaction that reduced the antibacterial effect. Nanoparticle inclusion promoted the anti-MRSA activity of ciprofloxacin according to time-kill curves. The NLCs were found to be largely internalized into neutrophils and exhibited superior superoxide anion inhibition than free drugs. Retinol incorporation into the nanocarriers facilitated their efficient targeting to the kidneys. The NLCs significantly mitigated MRSA burden and elastase distribution in the organs of MRSA-infected animals, and the greatest inhibition was observed in the kidneys. Bacterial clearance and neutrophil infiltration suppression attenuated the bacteremia-induced cytokine overexpression, leading to an improvement in the survival rate from 22% to 67%.

Conclusions

The dual role of our NLCs endowed them with greater efficacy in treating MRSA bacteremia than that of free drugs.

PDE3-inhibitor enoximone prevented mechanical ventilation in patients with SARS-CoV-2 pneumonia

BACKGROUND

Standard care in severe SARS-CoV-2 pneumonia complicated by severe dyspnea and respiratory failure, consists of symptom reduction, ultimately supported by mechanical ventilation. Patients with severe SARS-CoV-2, a prominent feature of COVID-19, show several similar symptoms to Critical Asthma Syndrome (CAS) patients, such as pulmonary edema, mucus plugging of distal airways, decreased tissue oxygenation, (emergent) exhaustion due to severe dyspnea and respiratory failure. Prior application of elective phosphodiesterase (PDE)3-inhibitors milrinone and enoximone in patients with CAS yielded rapid symptomatic relief and reverted the need for mechanical ventilation, due to their bronchodilator and anti-inflammatory properties. Based on these observations, we hypothesized that enoximone may be beneficial in the treatment of patients with severe SARS-CoV-2 pneumonia and prominent CAS-features.

METHODS

In this case report enoximone was administered to four consecutive patients (1 M; 3 F; 46-70 y) with emergent respiratory failure due to SARS-CoV-2 pneumonia. Clinical outcome was compared with three controls who received standard care only.

RESULTS

After an intravenous bolus of enoximone 20 mg followed by 10 mg/h via perfusor, a rapid symptomatic relief was observed: two out of four patients recovered within a few hours, the other two (with comorbid COPD GOLD II/III) responded within 24-36 h. Compared to the controls, in the enoximone-treated patients respiratory failure and further COVID-19-related deterioration was reverted and mechanical ventilation was prevented, leading to reduced hospital/ICU time.

DISCUSSION

Our preliminary observations suggest that early intervention with the selective PDE3-inhibitor enoximone may help to revert respiratory failure as well as avert mechanical ventilation, and reduces ICU/hospital time in patients with severe SARS-CoV-2 pneumonia. Our findings warrant further research on the therapeutic potential of PDE3-inhibition, alone or in combination with other anti-COVID-19 strategies.

Scope of adjuvant therapy using roflumilast, a PDE-4 inhibitor against COVID-19

The recent pandemic of COVID-19 caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents an extraordinary challenge to identify effective drugs for prevention and treatment. The pathogenesis implicate acute respiratory disorder (ARD) which is attributed to significantly triggered "cytokine storm" and compromised immune system. This article summarizes the likely benefits of roflumilast, a Phosphodiesterase-4 (PDE-4) inhibitor as a comprehensive support COVID-19 pathogenesis. Roflumilast, a well-known anti-inflammatory and immunomodulatory drug, is protective against respiratory models of chemical and smoke induced lung damage. There is significant data which demonstrate the protective effect of PDE-4 inhibitor in respiratory viral models and is likely to be beneficial in combating COVID-19 pathogenesis. Roflumilast is effective in patients with severe COPD by reducing the rate of exacerbations with the improvement of the lung function, which might further be beneficial for better clinical outcomes in COVID-19 patients. However, further clinical trials are warranted to examine this conjecture.

Adherence to the Mediterranean diet is an independent predictor of circulating vitamin D levels in normal weight and non-smoker adults: an observational cross-sectional study

We explored the association between circulating 25OHD and adherence to the Mediterranean Diet (MedDiet) in 402 Greek (21-65 years, 188 men and 214 women), normal weight, non-smoker, healthy volunteers in the Athens metropolitan area during summer and autumn, taking into account skin phototype, anthropometric, and lifestyle variables. Circulating 25OHD, parathormone, creatinine, calcium, and phosphate were determined. A vitamin D status of ≤25, ≤50, and ≤75 nmol/L was observed in 4.5, 37.3, and 74.1% of the subjects, respectively. The independent predictors of 25OHD deficiency were autumn, darker skin phototype, BMI, or waist circumference (WC), sunscreen use, less physical outdoor activity, and less adherence to the MedDiet. Higher intake of fish and olive oil was a positive independent predictor of elevated circulating 25OHD levels. In conclusion, higher adherence to the MedDiet, fish and olive oil consumption, were positively associated with circulating 25OHD independently from BMI or WC, skin phototype, season, and physical activity.

PDE4 inhibition as a therapeutic strategy for improvement of pulmonary dysfunctions in Covid-19 and cigarette smoking

Angiotensin-converting enzyme 2 (ACE2) is the binding-site and entry-point for SARS-CoV-2 in human and highly expressed in the lung. Cigarette smoking (CS) is the leading cause of pulmonary and cardiovascular diseases. Chronic CS leads to upregulation of bronchial ACE2 inducing a high vulnerability in COVID-19 smoker patients. Interestingly, CS-induced dysregulation of pulmonary renin-angiotensin system (RAS) in part contributing into the potential pathogenesis COVID-19 pneumonia and acute respiratory distress syndrome (ARDS). Since, CS-mediated ACE2 activations is not the main pathway for increasing the risk of COVID-19, it appeared that AngII/AT₁R might induce an inflammatory-burst in COVID-19 response by up-regulating cyclic nucleotide phosphodiesterase type 4 (PDE4), which hydrolyses specifically the second intracellular messenger 3′, 5′-cyclic AMP (cAMP). It must be pointed out that CS might induce PDE4 up-regulation similarly to the COVID-19 inflammation, and therefore could potentiate COVID-19 inflammation opening the potential therapeutic effects of PDE4 inhibitor in both COVID-19-inflammation and CS.

Could Oral Phosphodiesterase 5 Inhibitors Have a Potential Adjuvant Role in Combating COVID-19 Infection?

INTRODUCTION

The recent global outbreak of coronavirus disease 2019 (COVID-19) has become a pandemic with a lot of sufferers. Excessive inflammation, exaggerated immune response, with ultimate apoptosis contribute to COVID-19 pathology that progress to acute lung acute respiratory distress.

OBJECTIVE

To shed a light on the likely benefits of the oral phosphodiesterase 5 (PDE5) inhibitor adjuvant role in combating COVID-19 infection.

METHODS

A literature review was performed in the PubMed/Medline database, Scopus, Cochrane Library, EMBASE, Academic Search Complete, Google Scholar, and CINAHL databases using the keywords COVID-19; phosphodiesterase-5 inhibitors; cytokine storm; respiratory distress.

RESULTS

Despite the worsening trends of COVID-19, still no drugs are validated to have significant clinical efficacy in the treatment of patients with COVID-19 in large-scale studies. While the progress toward a curative agent and/or vaccine is certainly hopeful, the principal limiting factor in such public health emergencies is always the time. Therefore, a preexisting licensed therapeutic(s) might offer a reprieve to the healthcare systems operating at the edge of capacity. In this context, the innovation of oral PDE5 inhibitors with their valuable effects on erection have provided a breakthrough in the treatment of erectile dysfunction and opened new fields of clinical application for this class of drugs. Oral PDE5 inhibitors have been demonstrated to possess many beneficial useful additional implications with acknowledged anti-inflammatory, antioxidant, immune response regulation, and antiapoptotic properties. These properties have been elucidated through the nitric oxide/soluble guanylyl cyclase/cyclic guanylate monophosphate pathway in addition to the emerged hemeoxygenase-1 enzyme as well as hydrogen sulfide pathways. These properties could support repurposing oral PDE5 inhibitors' potential adjuvant use in targeting different aspects of COVID-19 infection.

CONCLUSION

Oral PDE5 inhibitors retain several acknowledged off-labeled useful implications with anti-inflammatory, antioxidant, immune response regulation, and antiapoptotic properties. These properties may support repurposing oral PDE5 inhibitors' potential adjuvant use in the protocols combating COVID-19 manifestations. Mostafa T. Could Oral Phosphodiesterase 5 Inhibitors Have a Potential Adjuvant Role in Combating Coronavirus Disease 2019 Infection? Sex Med Rev 2021;9:15-22.

Comorbidities burden and previous exposure to biological agents may predict drug survival of apremilast for psoriasis in a real-world setting

Apremilast is the first small molecule approved for the treatment of moderate to severe psoriasis and psoriatic arthritis in adult patients. To evaluate survival, efficacy and safety of apremilast in patients with moderate to severe psoriasis and investigate possible associations between apremilast survival and clinical parameters in a real-world setting. In this retrospective study, a total of 71 patients who started on apremilast treatment between March 2017 and December 2019 were identified and included in the study: 40 (56.3%) males and 31 (43.7%) females, with a mean age of 55.6 ± 13.8 years and a mean Body Mass Index of 28.4 ± 6.9 kg/m² . At the end of the study 49.3% of patients remained on apremilast with mean treatment duration 67.2 ± 41.1 weeks (range 4-132). Overall, mean drug survival duration was 78.51 weeks (95% CI: 65.8-91.2 weeks). Mean drug survival was shorter when comorbidities burden was higher (P = .012) and with previous exposure of biological agents (P = .001). Previous exposure to biological agents (HR:3.86, 95% CI: 1.35-11.04, P = .012) and comorbidities burden (HR: 2.27, 95% CI: 1.25-4.12, P = .007) were independent predictors of drug discontinuation adjusting for important clinical parameters. In this real-world setting, apremilast presented better survival rates when introduced early on the onset of moderate psoriasis, especially in biologic naïve patients with less comorbidities. More prospective and larger studies are required to determine clinical parameters affecting drug survival.

Could Oral Phosphodiesterase 5 Inhibitors Have a Potential Adjuvant Role in Combating COVID-19 Infection?

INTRODUCTION

The recent global outbreak of coronavirus disease 2019 (COVID-19) has become a pandemic with a lot of sufferers. Excessive inflammation, exaggerated immune response, with ultimate apoptosis contribute to COVID-19 pathology that progress to acute lung acute respiratory distress.

OBJECTIVE

To shed a light on the likely benefits of the oral phosphodiesterase 5 (PDE5) inhibitor adjuvant role in combating COVID-19 infection.

METHODS

A literature review was performed in the PubMed/Medline database, Scopus, Cochrane Library, EMBASE, Academic Search Complete, Google Scholar, and CINAHL databases using the keywords COVID-19; phosphodiesterase-5 inhibitors; cytokine storm; respiratory distress.

RESULTS

Despite the worsening trends of COVID-19, still no drugs are validated to have significant clinical efficacy in the treatment of patients with COVID-19 in large-scale studies. While the progress toward a curative agent and/or vaccine is certainly hopeful, the principal limiting factor in such public health emergencies is always the time. Therefore, a preexisting licensed therapeutic(s) might offer a reprieve to the healthcare systems operating at the edge of capacity. In this context, the innovation of oral PDE5 inhibitors with their valuable effects on erection have provided a breakthrough in the treatment of erectile dysfunction and opened new fields of clinical application for this class of drugs. Oral PDE5 inhibitors have been demonstrated to possess many beneficial useful additional implications with acknowledged anti-inflammatory, antioxidant, immune response regulation, and antiapoptotic properties. These properties have been elucidated through the nitric oxide/soluble guanylyl cyclase/cyclic guanylate monophosphate pathway in addition to the emerged hemeoxygenase-1 enzyme as well as hydrogen sulfide pathways. These properties could support repurposing oral PDE5 inhibitors' potential adjuvant use in targeting different aspects of COVID-19 infection.

CONCLUSION

Oral PDE5 inhibitors retain several acknowledged off-labeled useful implications with anti-inflammatory, antioxidant, immune response regulation, and antiapoptotic properties. These properties may support repurposing oral PDE5 inhibitors' potential adjuvant use in the protocols combating COVID-19 manifestations. Mostafa T. Could Oral Phosphodiesterase 5 Inhibitors Have a Potential Adjuvant Role in Combating Coronavirus Disease 2019 Infection? Sex Med Rev 2021;9:15-22.

Quinazoline-Schiff base conjugates: in silico study and ADMET predictions as multi-target inhibitors of coronavirus (SARS-CoV-2) proteins

The 2019 coronavirus (COVID-19) pandemic is spreading worldwide, with a dramatic increase in death without any effective therapeutic treatment available up to now. We previously reported quinazoline-trihydroxyphenyl Schiff base conjugates as phosphodiesterase 4B (PDE 4B) inhibitors (an enzyme that plays an essential role in the early stages of COVID-19 pneumonia). Additionally, the structural similarity between these conjugates and identified anti-severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 flavonoids inspired us to in silico study their possible binding interactions with essential SARS-CoV-2 proteins. Thus, this study provides an insight into the potential bindings between quinazoline-Schiff base conjugates and SARS-CoV-2 proteins, including spike glycoprotein (SGp), main protease (Mpro) and RNA-dependent RNA polymerase (RdRp), to offer an opportunity to find an effective therapy. Besides this, based on the role that COVID-19 plays in iron dysmetabolism, the conjugate trihydroxyphenyl moiety should be reconsidered as an iron chelator. Moreover, molecular dynamics simulations of quinazoline derivative Ic bound to the mentioned targets were carried out. Finally, ADMET calculations were performed for the studied compounds to predict their pharmacokinetic profiles.

Phosphodiesterase Inhibitors: Could They Be Beneficial for the Treatment of COVID-19?

In March 2020, the World Health Organization declared the severe acute respiratory syndrome corona virus 2 (SARS-CoV2) infection to be a pandemic disease. SARS-CoV2 was first identified in China and, despite the restrictive measures adopted, the epidemic has spread globally, becoming a pandemic in a very short time. Though there is growing knowledge of the SARS-CoV2 infection and its clinical manifestations, an effective cure to limit its acute symptoms and its severe complications has not yet been found. Given the worldwide health and economic emergency issues accompanying this pandemic, there is an absolute urgency to identify effective treatments and reduce the post infection outcomes. In this context, phosphodiesterases (PDEs), evolutionarily conserved cyclic nucleotide (cAMP/cGMP) hydrolyzing enzymes, could emerge as new potential targets. Given their extended distribution and modulating role in nearly all organs and cellular environments, a large number of drugs (PDE inhibitors) have been developed to control the specific functions of each PDE family. These PDE inhibitors have already been used in the treatment of pathologies that show clinical signs and symptoms completely or partially overlapping with post-COVID-19 conditions (e.g., thrombosis, inflammation, fibrosis), while new PDE-selective or pan-selective inhibitors are currently under study. This review discusses the state of the art of the different pathologies currently treated with phosphodiesterase inhibitors, highlighting the numerous similarities with the disorders linked to SARS-CoV2 infection, to support the hypothesis that PDE inhibitors, alone or in combination with other drugs, could be beneficial for the treatment of COVID-19.

A Review on Currently Available Potential Therapeutic Options for COVID-19

A series of unexplained pneumonia cases currently were first reported in December 2019 in Wuhan, China. Official names have been announced for the virus responsible, previously known as "2019 novel coronavirus" and the diseases it causes are, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and coronavirus disease (COVID-19), respectively. Despite great efforts worldwide to control SARS-CoV-2, the spread of the virus has reached a pandemic. Infection prevention and control of this virus is the primary concern of public health officials and professionals. Currently, several therapeutic options for COVID-19 are proposed and vaccine development has been initiated for prevention purposes. In this review, we will discuss the most recent evidence about the current potential treatment options including anti-inflammatory drugs, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, nucleoside analogs, protease inhibitors, monoclonal antibodies, and convalescent plasma therapy. Some other agents such as vitamin D and melatonin, which were recommended as potential adjuvant treatments for COVID-19 infection are also presented. Moreover, the potential use of convalescent plasma for treatment of COVID-19 infection was described. Furthermore, in the next part of the current review, various vaccination approaches against COVID-19 including whole virus vaccines, recombinant subunit vaccine, DNA vaccines, and mRNA vaccines are discussed.