Structural-based design of HD-TAC7 PROteolysis TArgeting chimeras (PROTACs) candidate transformations to abrogate SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for about 672 million infections and 6.85 million deaths worldwide. Upon SARS-CoV-2 infection, Histone deacetylases (HDACs) hyperactivate the pro-inflammatory response resulting in stimulation of Acetyl-Coenzyme A and cholesterol for viral entry. HDAC3 inhibition results in the anti-inflammatory activity and reduction of pro-inflammatory cytokines that may restrict COVID-19 progression. Here, we have designed 44 conformational ensembles of previously known HD-TAC7 by enumerating torsions of dihedral angles tested for their binding preferences against HDAC3. Through scrutinizing their placements at active site and binding affinities, three hits were isolated. Cereblon (CRBN) is a well-known E3 ligase that facilitates Proteolysis Targeting Chimeras (PROTACs) targeting. Three entities, including HDAC3-binding moiety (4-acetamido-N-(2-amino-4 fluorophenyl) benzamide), a 6-carbon linker, and CRBN binding ligand (pomalidomide) were assembled to design 4 PROTACs followed by energy minimization and docking against HDAC3 and CRBN, respectively. Subsequent molecular dynamics (MD) and free energy analyses corroborated similar binding trends and favorable energy values. Among all cases, Met88, GLu106, Pro352, Trp380 and Trp388 residues of CRBN, and Pro23, Arg28, Lys194, Phe199, Leu266, Thr299 and Ile346 residues of HDAC3 were engaged in PROTAC binding. Thus, conformational dynamics of both HDAC3 and CRBN moieties are essential for the placement of PROTAC, resulting in target degradation. Overall, the proposed bifunctional small molecules may effectively target HDAC3, stimulating innate immune response to restrict COVID-19 hyperinflammation. This study supports the basis for designing new PROTACs by limiting the conformational search space that may prove more efficient for targeting the protein of interest.Communicated by Ramaswamy H. Sarma.

The main protease of SARS-CoV-2 cleaves histone deacetylases and DCP1A, attenuating the immune defense of the interferon-stimulated genes.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019, constitutes an emerging human pathogen of zoonotic origin. A critical role in protecting the host against invading pathogens is carried out by interferon-stimulated genes (ISGs), the primary effectors of the type I interferon (IFN) response. All coronaviruses studied thus far have to first overcome the inhibitory effects of the IFN/ISG system before establishing efficient viral replication. However, whether SARS-CoV-2 evades IFN antiviral immunity by manipulating ISG activation remains to be elucidated. Here, we show that the SARS-CoV-2 main protease (Mpro) significantly suppresses the expression and transcription of downstream ISGs driven by IFN-stimulated response elements in a dose-dependent manner, and similar negative regulations were observed in two mammalian epithelial cell lines (simian Vero E6 and human A549). Our analysis shows that to inhibit the ISG production, Mpro cleaves histone deacetylases (HDACs) rather than directly targeting IFN signal transducers. Interestingly, Mpro also abolishes the activity of ISG effector mRNA-decapping enzyme 1a (DCP1A) by cleaving it at residue Q343. In addition, Mpro from different genera of coronaviruses has the protease activity to cleave both HDAC2 and DCP1A, even though the alphacoronaviruse Mpro exhibits weaker catalytic activity in cleaving HDAC2. In conclusion, our findings clearly demonstrate that SARS-CoV-2 Mpro constitutes a critical anti-immune effector that modulates the IFN/ISG system at multiple levels, thus providing a novel molecular explanation for viral immune evasion and allowing for new therapeutic approaches against coronavirus disease 2019 infection.

HDAC Inhibition as Potential Therapeutic Strategy to Restore the Deregulated Immune Response in Severe COVID-19.

The COVID-19 pandemic has had a devastating impact worldwide and has been a great challenge for the scientific community. Vaccines against SARS-CoV-2 are now efficiently lessening COVID-19 mortality, although finding a cure for this infection is still a priority. An unbalanced immune response and the uncontrolled release of proinflammatory cytokines are features of COVID-19 pathophysiology and contribute to disease progression and worsening. Histone deacetylases (HDACs) have gained interest in immunology, as they regulate the innate and adaptative immune response at different levels. Inhibitors of these enzymes have already proven therapeutic potential in cancer and are currently being investigated for the treatment of autoimmune diseases. We thus tested the effects of different HDAC inhibitors, with a focus on a selective HDAC6 inhibitor, on immune and epithelial cells in in vitro models that mimic cells activation after viral infection. Our data indicate that HDAC inhibitors reduce cytokines release by airway epithelial cells, monocytes and macrophages. This anti-inflammatory effect occurs together with the reduction of monocytes activation and T cell exhaustion and with an increase of T cell differentiation towards a T central memory phenotype. Moreover, HDAC inhibitors hinder IFN-I expression and downstream effects in both airway epithelial cells and immune cells, thus potentially counteracting the negative effects promoted in critical COVID-19 patients by the late or persistent IFN-I pathway activation. All these data suggest that an epigenetic therapeutic approach based on HDAC inhibitors represents a promising pharmacological treatment for severe COVID-19 patients.

Neuromodulatory effects of SARS-CoV2 infection: Possible therapeutic targets.

INTRODUCTION: Although SARS-CoV-2 primarily manifests in the form of respiratory symptoms, emerging evidence suggests that the disease is associated with numerous neurological complications, such as stroke and Guillain-Barre syndrome. Hence, further research is necessary to seek possible therapeutic targets in the CNS for effective management of these complications. AREAS COVERED: This review examines the neurological complications associated with SARS-CoV-2 infections and the possible routes of infection. It progresses to illuminate the possible therapeutic targets for effective management of these neuromodulatory effects and the repurposing of drugs that could serve this purpose. To this end, literature from the year 1998-2021 was derived from PubMed. EXPERT OPINION: The neurological manifestations associated with COVID-19 may be related to poor prognosis and higher comorbidity. Identification of the key molecular targets in the brain that are potential indicators of the observed neuropathology, such as inflammatory mediators and chromatin modifiers, is key. The repurposing of existing drugs to target potential candidates could reduce the mortality attributed to these associated neurological complications.

Cardiovascular risk in COVID-19 infection.

A few months ago a new coronavirus was identified in Cina officially named by the WHO as COVID-19. The thousands of patients who died showed pneumonia and alveolar damage, but actually, according to several authors in addition to the acute respiratory distress syndrome the virus can give rise to multiorgan failure. In fact, many people died equally despite being intubated and treated for respiratory failure. In this review, we especially wanted to describe the virus effects on the cardiovascular system, probably the leading cause of death of thousands of deceased patients. Therefore, mortality is indirectly induced by the virus through vascular inflammation and cardiovascular damage and patients with severe COVID-19 infection showed significantly increased levels of cardiac troponin I and inflammatory cytokines. The main activation of the signal pathways for the production of inflammatory cytokines are the toll-like receptors that recognize the presence of viral nucleic acids and the ACE-2 receptors, that the virus uses to infect the cells. The binding to ACE-2 also allows to promote high levels of angiotensin II by promoting high levels of blood pressure. High levels of IL-6, IL-1B and IL-8 have been associated with plaque instability and increased thrombotic risk. Furthermore IL-6 is involved in the stimulation of matrix-degrading enzymes such as matrix metalloproteinases, and may contribute to the development of acute coronary syndrome. In addition, TNF-α, IL-1 and IL-6 present in patients with severe COVID-19 are associated with coagulation activation and thrombin generation resulting in disseminated intravascular coagulation or thrombotic microangiopathy. Considering these pathological effects of the virus, anti-inflammatory and anticoagulant treatments are to be considered to avoid cardiovascular events. In this regard, heparin, in addition to its anticoagulant characteristics, has been shown to have good control over inflammation and to be a good anti-viral drug.

[Coronavirus disease (COVID-19) and sirtuins]. / Enfermedad del coronavirus (covid-19) y las sirtuinas.

Introduction: The NAD+dependent proteins deacetylases are called Sirtuins (SIRT). Objectives: Objectives: this review is to study the sirtuins involved in cancer, as well as SIRT1 inhibition studies in patients with coronavirus disease COVID-19. Data source and selection: For this, a search was made in Medline, Scopus and WOS, where descriptive studies of each of the functions of sirtuins were included, adjusted to recent scientific research. SIRT1 inhibition reduces CD8 T cell cytotoxicity in patients with systemic erythematosus lupus, being susceptible to SARS Cov-2 infections. SIRT2 is regulated by the secretion of IL-4 by eosinophils and the increase in SIRT2 increases hyperplasia, in contrast, SIRT3 promotes angiogenesis, inducing cardiac remodeling. SIRT4 is a tumor suppressor, in contrastto SIRT5 that promotes cell proliferation causing colorectal cancer; SIRT6 attenuates herpes virus associated with Kaposi's Sarcoma (KSHV) in immune compromised patients. Suppression of SIRT7 inhibits the growth of endometrial cancer cells. Conclusions: It is concluded that SIRT1, SIRT2 and SIRT4 are involved in the development of cancer, the suppression of SIRT5 and SIRT7 promotes the apoptosis of cancer cells and SIRT6 attenuates the replication of KSHV, in addition to the molecular pathology pathway of COVID-19 is associated with the inhibition of SIRT1 activity that may be related to inflammatory processes.

Introducción: Las proteínas desacetilasas dependientes del NAD+, se denominan Sirtuinas (SIRT). Objetivos: estudiar las sirtuinas involucradas en el cáncer, así como los estudios de inhibición de SIRT1 en pacientes con la enfermedad del coronavirus COVID-19. Fuente y selección de datos: Para ello se realizó una búsqueda en Medline, Scopus y WOS, donde se incluyeron estudios descriptivos de cada una de las funciones de las sirtuinas ajustado a las recientes investigaciones científicas. La inhibición de SIRT1 disminuye la citotoxicidad de las células T CD8 en pacientes con lupus eritematoso sistémico, siendo susceptibles a infecciones por SARS CoV-2. La SIRT2 se regula por la secreción de IL-4 por los eosinófilos y el aumento de SIRT2 incrementa la hiperplasia, en contraste la SIRT3 promueve la angiogénesis, induciendo la remodelación cardiaca. La SIRT4 es un supresor de tumores, en contraste con la SIRT5 que promueve la proliferación celular provocando el cáncer colorrectal; la SIRT6 atenúa al herpes virus asociado al Sarcoma de Kaposi (KSHV) en pacientes inmuno comprometidos. La supresión de SIRT7 inhibe el crecimiento de las células cancerígenas endometriales. Conclusiones: Se concluye que las SIRT1, SIRT2 y SIRT4 están involucradas en el desarrollo del cáncer, la supresión de SIRT5 y SIRT7 promueve la apoptosis de células cancerígenas y la SIRT6 atenúa la replicación de KSHV, además la vía de patología molecular de la COVID-19 está asociada a la inhibición de la actividad de SIRT1 que puede estar relacionada a procesos inflamatorios.