Anti-inflammatory and antiviral effects of minocycline in enterovirus 71 infections

Emerging concerns of blood-brain barrier dysfunction caused by neurotropic enteroviral infections

Enteroviruses (EVs), comprise a genus in the Picornaviridae family, which have been shown to be neurotropic and can cause various neurological disorders or long-term neurological condition, placing a huge burden on society and families. The blood-brain barrier (BBB) is a protective barrier that prevents dangerous substances from entering the central nervous system (CNS). Recently, numerous EVs have been demonstrated to have the ability to disrupt BBB, and further lead to severe neurological damage. However, the precise mechanisms of BBB disruption associated with these EVs remain largely unknown. In this Review, we focus on the molecular mechanisms of BBB dysfunction caused by EVs, emphasizing the invasiveness of enterovirus A71 (EVA71), which will provide a research direction for further treatment and prevention of CNS disorders.

Recent Advances in Enterovirus A71 Infection and Antiviral Agents

Enterovirus A71 (EV-A71) is one of the major causative agents of hand, foot, and mouth disease (HFMD) that majorly affects children. Most of the time, HFMD is a mild disease but can progress to severe complications, such as meningitis, brain stem encephalitis, acute flaccid paralysis, and even death. HFMD caused by EV-A71 has emerged as an acutely infectious disease of highly pathogenic potential in the Asia-Pacific region. In this review, we introduced the properties and life cycle of EV-A71, and the pathogenesis and the pathophysiology of EV-A71 infection, including tissue tropism and host range of virus infection, the diseases caused by the virus, as well as the genes and host cell immune mechanisms of major diseases caused by enterovirus 71 (EV-A71) infection, such as encephalitis and neurologic pulmonary edema. At the same time, clinicopathologic characteristics of EV-A71 infection were introduced. There is currently no specific medication for EV-A71 infection, highlighting the urgency and significance of developing suitable anti-EV-A71 agents. This overview also summarizes the targets of existing anti-EV-A71 agents, including virus entry, translation, polyprotein processing, replication, assembly and release; interferons; interleukins; the mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and protein kinase B signaling pathways; the oxidative stress pathway; the ubiquitin-proteasome system; and so on. Furthermore, it overviews the effects of natural products, monoclonal antibodies, and RNA interference against EV-A71. It also discusses issues limiting the research of antiviral drugs. This review is a systematic and comprehensive summary of the mechanism and pathological characteristics of EV-A71 infection, the latest progress of existing anti-EV-A71 agents. It would provide better understanding and guidance for the research and application of EV-A71 infection and antiviral inhibitors.

Drug Repositioning for Hand, Foot, and Mouth Disease

Hand, foot, and mouth disease (HFMD) is a highly contagious disease in children caused by a group of enteroviruses. HFMD currently presents a major threat to infants and young children because of a lack of antiviral drugs in clinical practice. Drug repositioning is an attractive drug discovery strategy aimed at identifying and developing new drugs for diseases. Notably, repositioning of well-characterized therapeutics, including either approved or investigational drugs, is becoming a potential strategy to identify new treatments for virus infections. Various types of drugs, including antibacterial, cardiovascular, and anticancer agents, have been studied in relation to their therapeutic potential to treat HFMD. In this review, we summarize the major outbreaks of HFMD and the progress in drug repositioning to treat this disease. We also discuss the structural features and mode of action of these repositioned drugs and highlight the opportunities and challenges of drug repositioning for HFMD.

Antiviral Activity of Approved Antibacterial, Antifungal, Antiprotozoal and Anthelmintic Drugs: Chances for Drug Repurposing for Antiviral Drug Discovery

Drug repurposing process aims to identify new uses for the existing drugs to overcome traditional de novo drug discovery and development challenges. At the same time, as viral infections became a serious threat to humans and the viral organism itself has a high ability to mutate genetically, and due to serious adverse effects that result from antiviral drugs, there are crucial needs for the discovery of new antiviral drugs, and to identify new antiviral effects for the exciting approved drugs towards different types of viral infections depending on the observed antiviral activity in preclinical studies or clinical findings is one of the approaches to counter the viral infections problems. This narrative review article summarized mainly the published preclinical studies that evaluated the antiviral activity of drugs that are approved and used mainly as antibacterial, antifungal, antiprotozoal, and anthelmintic drugs, and the preclinical studies included the in silico, in vitro, and in vivo findings, additionally some clinical observations were also included while trying to relate them to the preclinical findings. Finally, the structure used for writing about the antiviral activity of the drugs was according to the families of the viruses used in the studies to form a better image for the target of antiviral activity of different drugs in the different kinds of viruses and to relate between the antiviral activity of the drugs against different strains of viruses within the same viral family.

Integrating heterogeneous data to facilitate COVID-19 drug repurposing

In the COVID-19 pandemic, drug repositioning has presented itself as an alternative to the time-consuming process of generating new drugs. This review describes a drug repurposing process that is based on a new data-driven approach: we put forward five information paths that associate COVID-19-related genes and COVID-19 symptoms with drugs that directly target these gene products, that target the symptoms or that treat diseases that are symptomatically or genetically similar to COVID-19. The intersection of the five information paths results in a list of 13 drugs that we suggest as potential candidates against COVID-19. In addition, we have found information in published studies and in clinical trials that support the therapeutic potential of the drugs in our final list.

The contributory role of lymphocyte subsets, pathophysiology of lymphopenia and its implication as prognostic and therapeutic opportunity in COVID-19

The incidence of the novel coronavirus disease (COVID-19) outbreak caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has brought daunting complications for people as well as physicians around the world. An ever-increasing number of studies investigating the characteristics of the disease, day by day, is shedding light on a new feature of the virus with the hope that eventually these efforts lead to the proper treatment. SARS-CoV-2 activates antiviral immune responses, but in addition may overproduce pro-inflammatory cytokines, causing uncontrolled inflammatory responses in patients with severe COVID-19. This condition may lead to lymphopenia and lymphocyte dysfunction, which in turn, predispose patients to further infections, septic shock, and severe multiple organ dysfunction. Therefore, accurate knowledge in this issue is important to guide clinical management of the disease and the development of new therapeutic strategies in patients with COVID-19. In this review, we provide a piece of valuable information about the alteration of each subtype of lymphocytes and important prognostic factors associated with these cells. Moreover, through discussing the lymphopenia pathophysiology and debating some of the most recent lymphocyte- or lymphopenia-related treatment strategies in COVID-19 patients, we tried to brightening the foreseeable future for COVID-19 patients, especially those with severe disease.

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.

Pharmacological basis for the potential role of Azithromycin and Doxycycline in management of COVID-19

A novel corona virus SARS-CoV-2 has led to an outbreak of the highly infectious pandemic COVID-19 complicated viral pneumonia. Patients with risk factors frequently develop secondary infections where the role of appropriate antibiotics is mandatory. However, the efforts of drug repurposing lead to recognizing the role of certain antibiotics beyond the management of infection. The current review provided the detailed antiviral, immunomodulatory effect, unique pharmacokinetic profile of two antibiotics namely azithromycin (AZ) and doxycycline (DOX). It summarizes current clinical trials and concerns regarding safety issues of these drugs. Azithromycin (AZ) has amazing lung tissue access, wide range antibacterial efficacy, conceivable antiviral action against COVID-19. It also showed efficacy when combined with other antiviral drugs in limited clinical trials, but many clinicians raise concerns regarding cardiovascular risk in susceptible patients. DOX has a considerable role in the management of pneumonia, it has some advantages including cardiac safety, very good access to lung tissue, potential antiviral, and immunomodulation impact by several mechanisms. The pharmacological profiles of both drugs are heightening considering these medications for further studies in the management of COVID-19.

Effect of minocycline on the changes in the sewage chemical index and microbial communities in sewage pipes

With the increasing use of drugs in cities, the sewer is becoming the most suitable place for antibiotic accumulation and transfer. In order to reveal the occurrence and fate of antibiotic sewage during pipeline migration, we used an anaerobic reactor device to simulate the concentration change of minocycline in the sewer and its impact on the sewage quality. The results showed that 90.8 % of minocycline was removed during sewer transportation. In the presence of minocycline, although the consumption of Chemical Oxygen Demand and total nitrogen in the sewage did not change significantly, the consumption rate of total phosphorus, nitrate nitrogen and the growth rate of ammonia nitrogen at the front end of the pipeline were decreased from 29.4 %, 86.3 %, 60.3 % to 3.7 %, 81.5 %, 18.3 % respectively. Minocycline inhibited the reduction of SO₄^2-, while also reducing the production of H₂S gas and increasing the release of CH₄ gas. Moreover, the decline in the abundance of functional bacteria such as phosphorus accumulating organisms was consistent with the consumption of sewage nutrients. This experiment provides data support for the risk of wastewater leakage of medical and pharmaceutical wastewater into domestic sewage, and will helps to maintain the safe operation of actual sewage pipes.

Potential effectiveness and adverse implications of repurposing doxycycline in COVID-19 treatment

Introduction: COVID-19 infection with no known-specific drugs or vaccines has impacted mankind and has become beyond precedence. Currently, re-purposing of existing drugs is the only therapeutic option for managing COVID-19 symptoms and associated co-infections to reduce mortality. Antimicrobials as varied as antiparasitic, antiviral, and antibiotics are under various stages of evaluation.Areas covered: Recently, doxycycline, a broad-spectrum antibiotic that has also reported antiviral and anti-inflammatory properties was widely investigated in clinical trials, either alone or in combination with other drugs, and repurposed for COVID-19 treatment. In the review, the potential therapeutic applications of doxycycline in COVID-19 treatment and its potential adverse implications with respect to antimicrobial resistance bestowed by repurposing the antibiotic have been expounded.Expert opinion: 'Fighting disease with already existing antibiotics' and 'antimicrobial resistance progression' are like two arms of a balance that has to be carefully equilibrated. Any imbalance by the inappropriate or indiscriminate use of the repurposed drugs would cause a disastrous increase in antimicrobial resistance (AMR). Hence, cautious parallel assessment of potential long-term consequences of AMR is of great importance to mankind as its impacts would prevail even after the current pandemic.

Tetracycline and viruses: a possible treatment for COVID-19?

Tetracyclines have been used to treat many bacterial infections. The use of these antibiotics for the treatment of viral diseases dates to the 1960s to 1970s. Over the decades, the effect of tetracyclines on the pathogenesis of viral infections has been demonstrated both clinically and experimentally. Tetracyclines can act on viral infections either through their antibacterial properties or through direct antiviral action. This review focuses on clinical and experimental data that support the use of tetracycline in treating viral infections and highlights an important approach to slowing disease progression during viral infections. Tetracycline treatment might represent a strategy for eliminating the infection or inhibiting the progression of COVID-19.

Oral disease-modifying antirheumatic drugs and immunosuppressants with antiviral potential, including SARS-CoV-2 infection: a review

There have been several episodes of viral infection evolving into epidemics in recent decades, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the latest example. Its high infectivity and moderate mortality have resulted in an urgent need to find an effective treatment modality. Although the category of immunosuppressive drugs usually poses a risk of infection due to interference of the immune system, some of them have been found to exert antiviral properties and are already used in daily practice. Recently, hydroxychloroquine and baricitinib have been proposed as potential drugs for SARS-CoV-2. In fact, there are other immunosuppressants known with antiviral activities, including cyclosporine A, hydroxyurea, minocycline, mycophenolic acid, mycophenolate mofetil, leflunomide, tofacitinib, and thalidomide. The inherent antiviral activity could be a treatment choice for patients with coexisting rheumatological disorders and infections. Clinical evidence, their possible mode of actions and spectrum of antiviral activities are included in this review article.

LAY SUMMARY

Immunosuppressants often raise the concern of infection risks, especially for patients with underlying immune disorders. However, some disease-modifying antirheumatic drugs (DMARDs) with inherent antiviral activity would be a reasonable choice in the situation of concomitant viral infections and flare up of autoimmune diseases. This review covers DMARDs of treatment potential for SARS-CoV-2 in part I, and antiviral mechanisms plus trial evidence for viruses other than SARS-CoV-2 in part II.

Repurposing minocycline for COVID-19 management: mechanisms, opportunities, and challenges

INTRODUCTION

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly grown into a public health emergency that has placed the national health systems as well as scientific research communities under enormous pressures. Drug repurposing or repositioning is a well-known strategy that seeks to deploy existing licensed drugs for newer indications and provides the quickest possible transition from bench to clinics for unmet therapeutic needs. Given the current, urgent, and dire need for effective therapies against novel coronavirus-19, this approach is particularly appealing.

AREAS COVERED

Here, we review the significant anti-inflammatory, immunomodulatory, and antiviral properties of minocycline as potential mechanisms for efficacy against the novel coronavirus and highlight the promises and pitfalls of this approach.

EXPERT OPINION

As compared to other agents being investigated for COVID-19, minocycline offers distinct advantages in terms of potential efficacy in patients with life-threatening acute respiratory distress syndrome (ARDS) and myocardial injury, well-known safety and interaction profile, relatively low costs, and widespread availability. We call upon public and private funders to facilitate urgent and rigorous research efforts before evidence-based recommendations for its widespread use can be made.

[Enterovirus 71 can induce autophagy and apoptosis of THP-1 macrophages]

OBJECTIVE

To investigate enterovirus 71 (EV71)-induced of autophagy, apoptosis and the related signaling pathways in THP-1 macrophages.

METHODS

THP-1 macrophages were infected with EV71 at the multiplicity of infection (MOI) of 0.1 for 2, 8 or 16 h, and the cell proliferation and toxicity were analyzed using CCK-8 kit. The intracellular viral nucleic acid in THP-1 macrophages were detected by fluorescence quantitative PCR, and the ultrastructural changes of the cells were observed using transmission electron microscopy. Cell apoptosis induced by EV71 infection was detected using Hoechst 33342 staining and AnnexinV/PI double staining. Western blotting was performed for analysis of changes in autophagy and apoptosis of the cells and in the expressions of the related proteins. The effect of EV71 infection on apoptosis of THP-1 macrophages incubated with 3-MA and Ac-DEVD-CHO inhibitor for 2 h was assessed using Western blotting.

RESULTS

EV71 infection significantly lowered the cell survival rate of THP-1 macrophages at 2, 8 h and 16 h after the infection (P < 0.05). The total copy number of viral nucleic acid in THP-1 macrophages incubated with EV71 increased significantly and progressively over time (P < 0.01). Intracellular autophagosomes and virions could be seen in EV71-infected THP-1 macrophages. The total apoptotic rate of the infected cell also increased significantly over time (P < 0.01). EV71 infection significantly increased LC3 conversion (LC3-Ⅱ/ LC3-I) and the expression of cleaved caspase 3 protein and decreased the protein expressions of p62, Bcl-2 and caspase-3 (P < 0.01) without causing obvious changes in cleaved caspase-8 (P>0.05). 3-MA significantly inhibited the EV71-induced autophagy of THP-1 macrophages and reduced LC3 conversion (LC3-Ⅱ/LC3-I) and p62 protein expression at 8 h after EV71 infection (P < 0.01). Compared with DMSO, Ac-DEVD-CHO significantly inhibited EV71-induced apoptosis of THP-1 macrophages (15.5% vs 7.7%, P < 0.01).

CONCLUSIONS

EV71 not only can infect and replicate in THP-1 macrophages, but also induces autophagy and cell apoptosis possibly by activating LC3/p62 autophagy pathway and caspase apoptosis pathway.

Doxycycline as a potential partner of COVID-19 therapies

Coronavirus disease 2019 (COVID-19) is a major public health challenge, and the current antiviral arsenal for treatment is limited, with questionable efficacy. Major efforts are under way for discovery of new effective agents, but the validation of new potential treatments for COVID-19 may take a long time. Therefore, the repurposing of existing drugs for new indications is needed. In this article, we argue for the potential benefits of using doxycycline with either hydroxycholoroquine or other putative agents for COVID-19 treatment, as doxycycline has antiviral and anti-inflammatory activities by dampening the cytokine storm and to prevent lung damage.

Antiviral Activity of a Llama-Derived Single-Domain Antibody against Enterovirus A71

In the past few decades, enterovirus A71 (EVA71) has caused devastating outbreaks in the Asia-Pacific region, resulting in serious sequelae in infected young children. No preventive or therapeutic interventions are currently available for curing EVA71 infection, highlighting a great unmet medical need for this disease. Here, we showed that one novel single-domain antibody (sdAb), F1, isolated from an immunized llama, could alleviate EVA71 infection both in vitro and in vivo We also confirmed that the sdAb clone F1 recognizes EVA71 through a novel conformational epitope comprising the highly conserved region of VP3 capsid protein by using competitive-binding and overlapping-peptide enzyme-linked immunosorbent assays (ELISAs). Because of the virion's icosahedral structure, we reasoned that adjacent epitopes must be clustered within molecular ranges that may be simultaneously bound by an engineered antibody with multiple valency. Therefore, two single-domain binding modules (F1) were fused to generate an sdAb-in-tandem design so that the capture of viral antigens could be further increased by valency effects. We showed that the tetravalent construct F1×F1-hFc, containing two sdAb-in-tandem on a fragment crystallizable (Fc) scaffold, exhibits more potent neutralization activity against EVA71 than does the bivalent sdAb F1-hFc by at least 5.8-fold. We also demonstrated that, using a human scavenger receptor class B member 2 (hSCARB2) transgenic mouse model, a half dose of the F1×F1-hFc provided better protection against EVA71 infection than did the F1-hFc. Thus, our study furnishes important insights into multivalent sdAb engineering against viral infection and provides a novel strategic deployment approach for preparedness of emerging infectious diseases such as EVA71.