Inhibition of the inflammatory cytokine tumor necrosis factor-alpha with etanercept provides protection against lethal H1N1 influenza infection in mice

Upregulation of key factors of viral entry of corona- and influenza viruses upon TLR3-signaling in cells from the respiratory tract and clinical treatment options by 1,8-Cineol

At the end of the 2019 coronavirus pandemic (COVID-19), highly contagious variants of coronaviruses had emerged. Together with influenza viruses, different variants of the coronavirus currently cause most colds and require appropriate drug treatment. We have investigated the expression of important factors for the replication of these viruses, namely transmembrane protease serine subtype 2 (TMPRSS2), neuropilin1 (NRP1), and angiotensin converting enzyme 2 (ACE2) or tumor necrosis factor-α (TNF-α) after toll like receptor-3 (TLR-3) stimulation using RT-qPCR and flow cytometry (FC) analysis. As model served primary fibroblasts derived from the lung and nasal cavity, as well as epidermal stem cells and fully matured respiratory epithelium. The stimulated cell cultures were treated with pharmaceuticals (Dexamethasone and Enzalutamide) and the outcome was compared with the phytomedicine 1,8-Cineol. The stimulation of TLR3 is sufficient to induce the expression of exactly those targets that were highly expressed in the corresponding culture type, specifically ACE2 and TMPRSS2 in respiratory epithelial stem cells and NRP1 in fibroblast cells. It seems this self-perpetuating cycle of infection-driven upregulation of key viral replication factors by the innate immune system represents an evolutionary advantage for viruses using these transcripts as viral replication factors. Likewise, to the standard pharmaceuticals with proven clinical efficiency, 1,8-Cineol was able to disrupt this self-perpetuating cycle. Considering the minor side effects and negligible pharmacological interactions with other drugs, it is conceivable that an adjuvant or combinatorial therapy with 1,8-Cineol for respiratory diseases caused by corona- or influenza viruses would be beneficial.

miR-126a-5p inhibits H1N1-induced inflammation and matrix protease secretion in lung fibroblasts by targeting ADAMTS-4

Upregulation of ADAMTS-4 has been reported to have an important role in lung injury, and ADAMTS-4 expression is regulated by miR-126a-5p in abdominal aortic aneurysms. The aim of this study was to investigate whether miR-126a-5p/ADAMTS-4 plays a role in influenza-virus-induced lung injury. Lung fibroblasts were infected with H1N1 influenza virus to detect changes in miR-126a-5p and ADAMTS-4 expression, and cell viability was measured by CCK-8 assay. Inflammatory factors and matrix protease levels were examined using ELISA kits, and cell apoptosis was assessed by measuring the levels of apoptosis-related proteins. A dual luciferase assay was used to verify the regulatory relationship between miR-126a-5p and ADAMTS-4. H1N1 influenza virus reduced fibroblast viability, inhibited miR-126a-5p expression, and promoted ADAMTS-4 expression. Overexpression of miR-126a-5p attenuated the cellular inflammatory response, apoptosis, matrix protease secretion, and virus replication. Luciferase reporter assays revealed that miR-126a-5p inhibited ADAMTS-4 expression by targeting ADAMTS-4 mRNA. Further experiments showed that overexpression of ADAMTS-4 significantly reversed the inhibitory effects of miR-126a-5p on fibroblast inflammation, apoptosis, matrix protease secretion, and virus replication. Upregulation of miR-126a-5p inhibits H1N1-induced apoptosis, inflammatory factors, and matrix protease secretion, as well as virus replication in lung fibroblasts.

Meeting the Challenge of Controlling Viral Immunopathology

The mission of this review is to identify immune-damaging participants involved in antiviral immunoinflammatory lesions. We argue these could be targeted and their activity changed selectively by maneuvers that, at the same time, may not diminish the impact of components that help resolve lesions. Ideally, we need to identify therapeutic approaches that can reverse ongoing lesions that lack unwanted side effects and are affordable to use. By understanding the delicate balance between immune responses that cause tissue damage and those that aid in resolution, novel strategies can be developed to target detrimental immune components while preserving the beneficial ones. Some strategies involve rebalancing the participation of immune components using various approaches, such as removing or blocking proinflammatory T cell products, expanding regulatory cells, restoring lost protective cell function, using monoclonal antibodies (moAb) to counteract inhibitory molecules, and exploiting metabolic differences between inflammatory and immuno-protective responses. These strategies can help reverse ongoing viral infections. We explain various approaches, from model studies and some clinical evidence, that achieve innate and adaptive immune rebalancing, offering insights into potential applications for controlling chronic viral-induced lesions.

Beneficial and Detrimental Effects of Cytokines during Influenza and COVID-19

Cytokines are signaling molecules that play a role in myriad processes, including those occurring during diseases and homeostasis. Their homeostatic function begins during embryogenesis and persists throughout life, including appropriate signaling for the cell and organism death. During viral infections, antiviral cytokines such as interferons and inflammatory cytokines are upregulated. Despite the well-known benefits of these cytokines, their levels often correlate with disease severity, linking them to unfavorable outcomes. In this review, we discuss both the beneficial and pathological functions of cytokines and the potential challenges in separating these two roles. Further, we discuss challenges in targeting these cytokines during disease and propose a new method for quantifying the cytokine effect to limit the pathological consequences while preserving their beneficial effects.

Knockout of the Tnfa Gene Decreases Influenza Virus-Induced Histological Reactions in Laboratory Mice

Tumor necrosis factor alpha (TNF-α) is a cytokine that is responsible for many processes associated with immune response and inflammation. It is involved in the development of an antiviral response to many virus infections. This factor was shown to be activated in influenza A virus infection, which enhances production of other cytokines. The overexpression of these cytokines can lead to a cytokine storm. To study the role of TNF-α in the development of pathologies associated with viral infection, we generated a Tnfa knockout mouse strain. We demonstrated that these mice were characterized by a significant increase in the number of viral genomes compared to that in the parental strain, but the amount of live virus did not differ. A histopathology of the lungs in the genetically modified animals was significantly lower in terms of interalveolar septal infiltration. The generated model may be used to further study pathological processes in viral infections.

Controlling viral inflammatory lesions by rebalancing immune response patterns

In this review, we discuss a variety of immune modulating approaches that could be used to counteract tissue-damaging viral immunoinflammatory lesions which typify many chronic viral infections. We make the point that in several viral infections the lesions can be largely the result of one or more aspects of the host response mediating the cell and tissue damage rather than the virus itself being directly responsible. However, within the reactive inflammatory lesions along with the pro-inflammatory participants there are also other aspects of the host response that may be acting to constrain the activity of the damaging components and are contributing to resolution. This scenario should provide the prospect of rebalancing the contributions of different host responses and hence diminish or even fully control the virus-induced lesions. We identify several aspects of the host reactions that influence the pattern of immune responsiveness and describe approaches that have been used successfully, mainly in model systems, to modulate the activity of damaging participants and which has led to lesion control. We emphasize examples where such therapies are, or could be, translated for practical use in the clinic to control inflammatory lesions caused by viral infections.

SpTNF regulates apoptosis and antimicrobial peptide synthesis in mud crab (Scylla paramamosain) during white spot syndrome virus infection

Tumor necrosis factor (TNF) is an inflammatory cytokine that is important in cell survival, proliferation, differentiation, and death. However, the functions of TNF in the immune responses of invertebrates have been less studied. In this study, SpTNF was cloned and characterized from mud crab (Scylla paramamosain) for the first time. SpTNF contains an open reading frame of 354 bp encoding 117 deduced amino acids, with a conserved C-terminal TNF homology domain (THD) domain. RNAi knockdown of SpTNF reduced hemocyte apoptosis and antimicrobial peptide (AMP) synthesis. Expression of SpTNF was initially down-regulated but subsequently up-regulated after 48 h in hemocytes of mud crabs after WSSV infection. Results of RNAi knockdown and overexpression showed that SpTNF inhibits the WSSV infection through activating apoptosis, NF-κB pathway, and AMP synthesis. Furthermore, the lipopolysaccharide-induced TNF-α factor (SpLITAF) can regulate the expression of SpTNF, induction of apoptosis, and activation of the NF-κB pathway and AMP synthesis. The expression and nuclear translocation of SpLITAF were regulated by WSSV infection. SpLITAF knockdown increased the WSSV copy number and VP28 gene expression. Taken together, these results proved the protective function of SpTNF, which is regulated by SpLITAF, in the immune response of mud crabs against WSSV through the regulation of apoptosis and activation of AMP synthesis.

Myeloid autophagy genes protect mice against fatal TNF- and LPS-induced cytokine storm syndromes

ABBREVIATIONS

ATG5: autophagy related 5; ATG7: autophagy related 7; ATG14: autophagy related 14; ATG16L1: autophagy related 16-like 1 (S. cerevisiae); BECN1: beclin 1, autophagy related; CASP1: caspase 1; CASP4/CASP11: caspase 4, apoptosis-related cysteine peptidase; CIM: conditionally immortalized macrophage; CLP: cecal ligation and puncture; CSS: cytokine storm syndrome; DC: dendritic cell; IFNG/IFNγ: interferon gamma; IFNGR1: interferon gamma receptor 1; ip: intraperitoneal; iv: intravenous; IL12/p70: interleukin 12, p70 heterodimer; IL18: Interleukin 18; ITGAX/CD11c: integrin alpha X; LAP: LC3-associated phagocytosis; LPS: lipopolysaccharide; LYZ2/LYSM: lysozyme 2; MAP1LC3A/LC3: microtubule-associated protein 1 light chain 3 alpha; RB1CC1/FIP200: RB1-inducible coiled-coil 1; S100A8/MRP8: S100 calcium binding protein A8 (calgranulin A); TICAM1/TRIF: TIR domain containing adaptor molecule 1; TLR4: toll-like receptor 4; TNF: tumor necrosis factor.

In Vitro Antiviral and Anti-Inflammatory Activities of N-Acetylglucosamine: Development of an Alternative and Safe Approach to Fight Viral Respiratory Infections

Viral respiratory tract infections (RTIs) are responsible for significant morbidity and mortality worldwide. A prominent feature of severe respiratory infections, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is the cytokine release syndrome. Therefore, there is an urgent need to develop different approaches both against viral replication and against the consequent inflammation. N-acetylglucosamine (GlcNAc), a glucosamine (GlcN) derivative, has been developed as an immunomodulatory and anti-inflammatory inexpensive and non-toxic drug for non-communicable disease treatment and/or prevention. Recent studies have suggested that GlcN, due to its anti-inflammatory activity, could be potentially useful for the control of respiratory virus infections. Our present study aimed to evaluate in two different immortalized cell lines whether GlcNAc could inhibit or reduce both viral infectivity and the inflammatory response to viral infection. Two different viruses, frequent cause of upper and lower respiratory tract infections, were used: the H1N1 Influenza A virus (IAV) (as model of enveloped RNA virus) and the Human adenovirus type 2 (Adv) (as model of naked DNA virus). Two forms of GlcNAc have been considered, bulk GlcNAc and GlcNAc in nanoform to overcome the possible pharmacokinetic limitations of GlcNAc. Our study suggests that GlcNAc restricts IAV replication but not Adv infection, whereas nano-GlcNAc inhibits both viruses. Moreover, GlcNAc and mainly its nanoformulation were able to reduce the pro-inflammatory cytokine secretion stimulated by viral infection. The correlation between inflammatory and infection inhibition is discussed.

Therapeutic Targeting of Inflammation and Virus Simultaneously Ameliorates Influenza Pneumonia and Protects from Morbidity and Mortality

Influenza pneumonia is a severe complication caused by inflammation of the lungs following infection with seasonal and pandemic strains of influenza A virus (IAV), that can result in lung pathology, respiratory failure, and death. There is currently no treatment for severe disease and pneumonia caused by IAV. Antivirals are available but are only effective if treatment is initiated within 48 h of onset of symptoms. Influenza complications and mortality are often associated with high viral load and an excessive lung inflammatory cytokine response. Therefore, we simultaneously targeted the virus and inflammation. We used the antiviral oseltamivir and the anti-inflammatory drug etanercept to dampen TNF signaling after the onset of clinical signs to treat pneumonia in a mouse model of respiratory IAV infection. The combined treatment down-regulated the inflammatory cytokines TNF, IL-1β, IL-6, and IL-12p40, and the chemokines CCL2, CCL5, and CXCL10. Consequently, combined treatment with oseltamivir and a signal transducer and activator of transcription 3 (STAT3) inhibitor effectively reduced clinical disease and lung pathology. Combined treatment using etanercept or STAT3 inhibitor and oseltamivir dampened an overlapping set of cytokines. Thus, combined therapy targeting a specific cytokine or cytokine signaling pathway and an antiviral drug provide an effective treatment strategy for ameliorating IAV pneumonia. This approach might apply to treating pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Rapid improvement in severe long COVID following perispinal etanercept

BACKGROUND

This study aimed to describe the neurological improvements in a patient with severe long COVID brain dysfunction following perispinal etanercept administration. Perispinal administration of etanercept, a novel method designed to enhance its brain delivery via carriage in the cerebrospinal venous system, has previously been shown to reduce chronic neurological dysfunction after stroke. Etanercept is a recombinant biologic that is capable of ameliorating two components of neuroinflammation: microglial activation and the excess bioactivity of tumor necrosis factor (TNF), a proinflammatory cytokine that is a key neuromodulator in the brain. Optimal synaptic and brain network function require physiological levels of TNF. Neuroinflammation, including brain microglial activation and excess central TNF, can be a consequence of stroke or peripheral infection, including infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19.

METHODS

Standardized, validated measures, including the Montreal Cognitive Assessment, Beck Depression Index-II (BDI-II), Fatigue Assessment Scale, Controlled Oral Word Association Test, Trail Making Tests, Timed Finger-to-Nose Test, 20 m Self-Paced Walk Test, 5 Times Sit-to-Stand Test and Grip Strength measured with a Jamar Dynamometer were used to quantitate changes in cognition, depression, fatigue and neurological function after a single 25 mg perispinal etanercept dose in a patient with severe long COVID of 12 months duration.

RESULTS

Following perispinal etanercept administration there was immediate neurological improvement. At 24 h, there were remarkable reductions in chronic post-COVID-19 fatigue and depression, and significant measurable improvements in cognition, executive function, phonemic verbal fluency, balance, gait, upper limb coordination and grip strength. Cognition, depression and fatigue were examined at 29 days; each remained substantially improved.

CONCLUSION

Perispinal etanercept is a promising treatment for the chronic neurologic dysfunction that may persist after resolution of acute COVID-19, including chronic cognitive dysfunction, fatigue, and depression. These results suggest that long COVID brain neuroinflammation is a potentially reversible pathology and viable treatment target. In view of the increasing unmet medical need, clinical trials of perispinal etanercept for long COVID are urgently necessary. The robust results of the present case suggest that perispinal etanercept clinical trials studying long COVID populations with severe fatigue, depression and cognitive dysfunction may have improved ability to detect a treatment effect. Positron emission tomographic methods that image brain microglial activation and measurements of cerebrospinal fluid proinflammatory cytokines may be useful for patient selection and correlation with treatment effects, as well as provide insight into the underlying pathophysiology.

Emerging antiviral therapies and drugs for the treatment of influenza

INTRODUCTION

Both vaccines and antiviral drugs represent the mainstay for preventing and treating influenza. However, approved M2 ion channel inhibitors, neuraminidase inhibitors, polymerase inhibitors, and various vaccines cannot meet therapeutic needs because of viral resistance. Thus, the discovery of new targets for the virus or host and the development of more effective inhibitors are essential to protect humans from the influenza virus.

AREAS COVERED

This review summarizes the latest progress in vaccines and antiviral drug research to prevent and treat influenza, providing the foothold for developing novel antiviral inhibitors.

EXPERT OPINION

Vaccines embody the most effective approach to preventing influenza virus infection, and recombinant protein vaccines show promising prospects in developing next-generation vaccines. Compounds targeting the viral components of RNA polymerase, hemagglutinin and nucleoprotein, and the modification of trusted neuraminidase inhibitors are future research directions for anti-influenza virus drugs. In addition, some host factors affect the replication of virus in vivo, which can be used to develop antiviral drugs.

5-Methoxyflavone-induced AMPKα activation inhibits NF-κB and P38 MAPK signaling to attenuate influenza A virus-mediated inflammation and lung injury in vitro and in vivo

Influenza-related acute lung injury (ALI) is a life-threatening condition that results mostly from uncontrolled replication of influenza virus (IV) and severe proinflammatory responses. The methoxy flavonoid compound 5-methoxyflavone (5-MF) is believed to have superior biological activity in the treatment of cancer. However, the effects and underlying mechanism of 5-MF on IV-mediated ALI are still unclear. Here, we showed that 5-MF significantly improved the survival of mice with lethal IV infection and ameliorated IV-mediated lung edema, lung histological changes, and inflammatory cell lung recruitment. We found that 5-MF has antiviral activity against influenza A virus (IAV), which was probably associated with increased expression of radical S-adenosyl methionine domain containing 2 (RSAD2) and suppression of endosomal acidification. Moreover, IV-infected A549 cells with 5-MF treatment markedly reduced proinflammatory mediator expression (IL-6, CXCL8, TNF-α, CXCL10, CCL2, CCL3, CCL4, GM-CSF, COX-2, and PGE₂) and prevented P-IKBα, P-P65, and P-P38 activation. Interestingly, we demonstrated that 5-MF treatment could trigger activation of AMP-activated protein kinase (AMPK)α in IV-infected A549 cells, as evidenced by activation of the AMPKα downstream molecule P53. Importantly, the addition of AMPKα blocker compound C dramatically abolished 5-MF-mediated increased levels of RSAD2, the inhibitory effects on H1N1 virus-elicited endosomal acidification, and the suppression expression of proinflammatory mediators (IL-6, TNF-α, CXCL10, COX-2 and PGE₂), as well as the inactivation of P-IKBα, P-P65, and P-P38 MAPK signaling pathways. Furthermore, inhibition of AMPKα abrogated the protective effects of 5-MF on H1N1 virus-mediated lung injury and excessive inflammation in vivo. Taken together, these results indicate that 5-MF alleviated IV-mediated ALI and suppressed excessive inflammatory responses through activation of AMPKα signaling.

Modulating cholesterol-rich lipid rafts to disrupt influenza A virus infection

Influenza A virus (IAV) is widely disseminated across different species and can cause recurrent epidemics and severe pandemics in humans. During infection, IAV attaches to receptors that are predominantly located in cell membrane regions known as lipid rafts, which are highly enriched in cholesterol and sphingolipids. Following IAV entry into the host cell, uncoating, transcription, and replication of the viral genome occur, after which newly synthesized viral proteins and genomes are delivered to lipid rafts for assembly prior to viral budding from the cell. Moreover, during budding, IAV acquires an envelope with embedded cholesterol from the host cell membrane, and it is known that decreased cholesterol levels on IAV virions reduce infectivity. Statins are commonly used to inhibit cholesterol synthesis for preventing cardiovascular diseases, and several studies have investigated whether such inhibition can block IAV infection and propagation, as well as modulate the host immune response to IAV. Taken together, current research suggests that there may be a role for statins in countering IAV infections and modulating the host immune response to prevent or mitigate cytokine storms, and further investigation into this is warranted.

Liver-Targeted Nanoparticles Facilitate the Bioavailability and Anti-HBV Efficacy of Baicalin In Vitro and In Vivo

The anti-hepatitis B virus (HBV) efficacy of baicalin (BA) is mediated by HBV-related hepatocyte nuclear factors (HNFs). However, this efficacy is severely limited by the low bioavailability of BA. Therefore, a novel liver-targeted BA liposome was constructed to promote the bioavailability and antiviral ability of BA. The results showed that apolipoprotein A1 (ApoA1)–modified liposomes (BAA1) significantly enhanced BA’s cellular uptake and specific distribution in the liver. Furthermore, the substantial inhibitory effects of BAA1 on HBsAg, HBeAg, HBV RNA, and HBV DNA were assessed in HB-infected cells and mice. Western blotting, co-immunoprecipitation, and transcriptomics analysis further revealed that the enhanced anti-HBV efficacy of BAA1 was attributed to the interaction between hepatocyte nuclear factors (HNFs) and estrogen receptors (ERs). Based on the findings, we propose that the ApoA1-modified liposomes aid BA in inhibiting HBV transcription and replication by augmenting its bioavailability and the HNFs–ERs axis.

Autophagy and Exosome Coordinately Enhance Macrophage M1 Polarization and Recruitment in Influenza A Virus Infection

Background

Influenza A virus infection results in viral pneumonia, which is often accompanied by the infiltration and recruitment of macrophages, overactivation of inflammatory responses, and obvious cell autophagy and exosome production. However, little is known about the roles of autophagy and exosome production in these inflammatory responses.

Methods

In this study, multiple methods, such as flow cytometry, real-time quantitative reverse transcription-polymerase chain reaction, immune–fluorescence technology, and western blot, were applied to explore the possible effects of autophagy and exosome production by H1N1-infected host cells.

Results

It was observed that a high number of polarized macrophages (CD11b⁺/F4/80⁺/CD86⁺) were recruited to the lung tissues of infected mice, which could be mimicked by tracking the movement of macrophages to H1N1-infected cells in vitro (transwell assays). Furthermore, there was some coordinated upregulation of M1 polarization signs (iNOS/Arg-1 bias) as well as autophagy (LC3) and exosome (CD63) biomarkers in the infected macrophages and epithelial cells. Moreover, exosomes extracted from the supernatant of virus-infected cells were shown to promote the recruitment and polarization of more peritoneal macrophages than the normal group. The fluorescence colocalization of LC3-CD63 and the inhibition of autophagy and exosome signaling pathway further revealed that H1N1 infection seemed to sequentially activate the M1 polarization and recruitment of macrophages via autophagy–exosome dependent pathway.

Conclusion

Autophagy and exosome production coordinately enhance the M1 polarization and recruitment of macrophages in influenza virus infection, which also provides potential therapeutic targets.

Cangma Huadu granules, a new drug with great potential to treat coronavirus and influenza infections, exert its efficacy through anti-inflammatory and immune regulation

ETHNOPHARMACOLOGICAL RELEVANCE

Coronavirus and influenza virus infection seriously threaten human health. Cangma Huadu Granules (CMHD) is an in-hospital preparation composed of eight traditional Chinese medicines (TCM), which has been clinically used against COVID-19 in China and may be a promising candidate for the treatment of influenza. However, the role of its treatment urgently needs to be studied.

AIM OF THE STUDY

To evaluate the therapeutic effects of CMHD on pneumonia induced by coronavirus (HCoV-229E) and influenza A virus (H1N1/FM1) in mice and explore its mechanism of anti-infection.

MATERIALS AND METHODS

Mice were infected with HCoV-229E or H1N1/FM1 virus through the nasal cavity. CMHD (12.1, 6.05 and 3.03 g/kg/d) or the positive control drugs were administered intragastrically. The lung index and histopathological changes were used to evaluate the therapeutic effect of CMHD. The expression of TNF-α, IL-1β, IL-6 and IL-4 in Serum and the proportion of CD4+ and CD8+ T lymphocytes in peripheral blood were detected to evaluate the anti-inflammatory and immune regulation effects of CMHD, respectively. Furthermore, the levels of p-NF-κBp65/ NF-κB p65, which was the key targets of the NF-κB pathway was analyzed.

RESULTS

In HCoV-229E-induced pneumonia, the lung index was markedly reduced, and lung pathology was improved in mice that treated with CMHD (12.1, 6.05 g/kg/d). Meanwhile, the expression of TNF-α, IL-6 were obviously inhibited, but the expression of IL-4 was significantly increased in CMHD groups. Compared with the model group, CMHD could also markedly upregulate the level of CD4+ and CD8+. Furthermore, CMHD has a markedly effect on inhibit the expression of p-NF-κB p65/NF-κB p65 in the lung. In H1N1-induced pneumonia, the lung index of mice in the CMHD (12.1 g/kg/d) treatment group was lower than that in the model group, and less inflammatory infiltration could be seen in the lung pathological. Moreover, CMHD could also obviously decrease the expression of TNF-α, IL-1β, IL-6, but significantly increase the expression of IL-4. Except for that, CMHD could also markedly downregulate the level of CD4+ and upregulate the level of CD8+ compared with the model group. In addition, CMHD has a markedly effect on inhibit the expression of p-NF-κB p65/NF-κB p65 in the lung.

CONCLUSION

CMHD can significantly combats viral infections caused by HCoV-229E and H1N1, and the mechanism may be related to its multiple functions of anti-inflammatory, immunity regulating and inhibiting NF-κB signal transduction pathway.

Targeting ectromelia virus and TNF/NF-κB or STAT3 signaling for effective treatment of viral pneumonia

Viral causes of pneumonia pose constant threats to global public health, but there are no specific treatments currently available for the condition. Antivirals are ineffective when administered late after the onset of symptoms. Pneumonia is caused by an exaggerated inflammatory cytokine response to infection, but tissue necrosis and damage caused by virus also contribute to lung pathology. We hypothesized that viral pneumonia can be treated effectively if both virus and inflammation are simultaneously targeted. Combined treatment with the antiviral drug cidofovir and etanercept, which targets tumor necrosis factor (TNF), down-regulated nuclear factor kappa B-signaling and effectively reduced morbidity and mortality during respiratory ectromelia virus (ECTV) infection in mice even when treatment was initiated after onset of clinical signs. Treatment with cidofovir alone reduced viral load, but animals died from severe lung pathology. Treatment with etanercept had no effect on viral load but diminished levels of inflammatory cytokines and chemokines including TNF, IL-6, IL-1β, IL-12p40, TGF-β, and CCL5 and dampened activation of the STAT3 cytokine-signaling pathway, which transduces signals from multiple cytokines implicated in lung pathology. Consequently, combined treatment with a STAT3 inhibitor and cidofovir was effective in improving clinical disease and lung pathology in ECTV-infected mice. Thus, the simultaneous targeting of virus and a specific inflammatory cytokine or cytokine-signaling pathway is effective in the treatment of pneumonia. This approach might be applicable to pneumonia caused by emerging and re-emerging viruses, like seasonal and pandemic influenza A virus strains and severe acute respiratory syndrome coronavirus 2.

CD33 is downregulated by influenza virus H1N1pdm09 and induces ROS and the TNF-α, IL-1β, and IL-6 cytokines in human mononuclear cells

The influenza A virus (IAV) H1N1pdm09 induces exacerbated inflammation, contributing to disease complications. Inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), favor an inflammatory response that aids viral replication and survival. A pathway by which spontaneous TNF-α production occurs involves either the reduction of Siglec-3 (CD33) levels or the absence of its ligand, sialic acid. Influenza virus uses sialic acid to enter cells by reducing their expression; however, the role of CD33 in IAV H1N1pdm09 stimulation and its relationship with inflammation have not yet been studied. To evaluate the role of CD33 in proinflammatory cytokine production in IAV H1N1pdm09 stimulation, peripheral blood mononuclear cells from healthy subjects were incubated with IAV H1N1pdm09. We observed that the infection caused an increase in the mRNA expression of proinflammatory cytokines such as TNF-α, interleukin (IL)-1β, and IL-6 and a significant reduction in CD33 expression by monocytes at an early stage of infection. Additionally, suppressor of cytokine signaling 3 (SOCS-3) mRNA expression was upregulated at 6 h, and reactive oxygen species (ROS) production increased at 1.5 h. Moreover, a significant reduction in CD33 expression on the cell surface of monocytes from influenza patients or of IAV H1N1pdm09-stimulated monocytes incubated in vitro was observed by flow cytometry. The results suggest that the decrease in CD33 and increase of SOCS-3 expression induced by IAV H1N1pdm09 triggered TNF-α secretion and ROS production, suggesting an additional way to exacerbate inflammation during viral infection.

TNFA and IL10 Polymorphisms and IL-6 and IL-10 Levels Influence Disease Severity in Influenza A(H1N1)pdm09 Virus Infected Patients

Cytokines are key modulators of immune response, and dysregulated production of proinflammatory and anti-inflammatory cytokines contributes to the pathogenesis of influenza A(H1N1)pdm09 virus infection. Cytokine production is impacted by single nucleotide polymorphisms (SNPs) in the genes coding for them. In the present study, SNPs in the IL6, TNFA, IFNG, IL17A, IL10, and TGFB were investigated for their association with disease severity and fatality in influenza A(H1N1)pdm09-affected patients with mild disease (n = 293) and severe disease (n = 86). Among those with severe disease, 41 patients had fatal outcomes. In a subset of the patients, levels of IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ, and IL-17 were assayed in the plasma for their association with severe disease. The frequency of TNFA rs1800629 G/A allele was significantly higher in severe cases and survived severe cases group compared to that of those with mild infection (OR with 95% for mild vs. severe cases 2.95 (1.52–5.73); mild vs. survived severe cases 4.02 (1.84–8.82)). IL10 rs1800896-rs1800872 G-C haplotype was significantly lower (OR with 95% 0.34 (0.12–0.95)), while IL10 rs1800896-rs1800872 G-A haplotype was significantly higher (OR with 95% 12.11 (2.23–76.96)) in fatal cases group compared to that of the mild group. IL-6 and IL-10 levels were significantly higher in fatal cases compared to that of survived severe cases. IL-6 levels had greater discriminatory power than IL-10 to predict progression to fatal outcome in influenza A(H1N1)pdm09 virus-infected patients. To conclude, the present study reports the association of TNFA and IL10 SNPs with severe disease in Influenza A(H1N1)pdm09 virus-infected subjects. Furthermore, IL-6 levels can be a potential biomarker for predicting fatal outcomes in Influenza A(H1N1)pdm09 virus infected subjects.

Interferon Lambda Signaling in Macrophages Is Necessary for the Antiviral Response to Influenza

Interferon lambda (IFNλ) signaling is a promising therapeutic target against viral infection in murine models, yet little is known about its molecular regulation and its cognate receptor, interferon lambda receptor 1 (IFNLR1) in human lung. We hypothesized that the IFNλ signaling axis was active in human lung macrophages. In human alveolar macrophages (HAMs), we observed increased IFNLR1 expression and robust increase in interferon-stimulated gene (ISG) expression in response to IFNλ ligand. While human monocytes express minimal IFNLR1, differentiation of monocytes into macrophages with macrophage colony-stimulating factor (M-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) increased IFNLR1 mRNA, IFNLR1 protein expression, and cellular response to IFNλ ligation. Conversely, in mice, M-CSF or GM-CSF stimulated macrophages failed to produce ISGs in response to related ligands, IFNL2 or IFNL3, suggesting that IFNLR1 signaling in macrophages is species-specific. We next hypothesized that IFNλ signaling was critical in influenza antiviral responses. In primary human airway epithelial cells and precision-cut human lung slices, influenza infection substantially increased IFNλ levels. Pretreatment of both HAMs and differentiated human monocytes with IFNL1 significantly inhibited influenza infection. IFNLR1 knockout in the myeloid cell line, THP-1, exhibited reduced interferon responses to either direct or indirect exposure to influenza infection suggesting the indispensability of IFNLR1 for antiviral responses. These data demonstrate the presence of IFNλ - IFNLR1 signaling axis in human lung macrophages and a critical role of IFNλ signaling in combating influenza infection.

Role of tumor necrosis factor-α in the mortality of hospitalized patients with severe and critical COVID-19 pneumonia

The coronavirus disease 2019 (COVID-19) is presently the most pressing public health concern worldwide. Cytokine storm is an important factor leading to death of patients with COVID-19. This study aims to characterize serum cytokines of patients with severe or critical COVID-19. Clinical records were obtained from 149 patients who were tested at the Sino-French New City Branch of Tongji Hospital from 30 January to 30 March 2020. Data regarding the clinical features of the patients was collected and analyzed. Among the 149, 45 (30.2%) of them had severe conditions and 104 (69.8%) of that presented critical symptoms. In the meantime, 80 (53.7%) of that 149 died during hospitalization. Of all, male patients accounted for 94 (69.1%). Compared with patients in severe COVID-19, those who in critical COVID-19 had significantly higher levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-8, and IL-10. Moreover, the passed-away patients had considerably higher levels of TNF-α, IL-6, IL-8, and IL-10 than those survived from it. Regression analysis revealed that serum TNF-α level was an independent risk factor for the death of patient with severe conditions. Among the proinflammatory cytokines (IL-1β, TNF-α, IL-8, and IL-6) analyzed herein, TNF-α was seen as a risk factor for the death of patients with severe or critical COVID-19. This study suggests that anti-TNF-α treatment allows patients with severe or critical COVID-19 pneumonia to recover.

A Biosafety Level 2 Mouse Model for Studying Betacoronavirus-Induced Acute Lung Damage and Systemic Manifestations

The emergence of life-threatening zoonotic diseases caused by betacoronaviruses, including the ongoing coronavirus disease 19 (COVID-19) pandemic, has highlighted the need for developing preclinical models mirroring respiratory and systemic pathophysiological manifestations seen in infected humans. Here, we showed that C57BL/6J wild-type mice intranasally inoculated with the murine betacoronavirus murine hepatitis coronavirus 3 (MHV-3) develop a robust inflammatory response leading to acute lung injuries, including alveolar edema, hemorrhage, and fibrin thrombi. Although such histopathological changes seemed to resolve as the infection advanced, they efficiently impaired respiratory function, as the infected mice displayed restricted lung distention and increased respiratory frequency and ventilation. Following respiratory manifestation, the MHV-3 infection became systemic, and a high virus burden could be detected in multiple organs along with morphological changes. The systemic manifestation of MHV-3 infection was also marked by a sharp drop in the number of circulating platelets and lymphocytes, besides the augmented concentration of the proinflammatory cytokines interleukin 1 beta (IL-1β), IL-6, IL-12, gamma interferon (IFN-γ), and tumor necrosis factor (TNF), thereby mirroring some clinical features observed in moderate and severe cases of COVID-19. Importantly, both respiratory and systemic changes triggered by MHV-3 infection were greatly prevented by blocking TNF signaling, either via genetic or pharmacologic approaches. In line with this, TNF blockage also diminished the infection-mediated release of proinflammatory cytokines and virus replication of human epithelial lung cells infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Collectively, results show that MHV-3 respiratory infection leads to a large range of clinical manifestations in mice and may constitute an attractive, lower-cost, biosafety level 2 (BSL2) in vivo platform for evaluating the respiratory and multiorgan involvement of betacoronavirus infections. IMPORTANCE Mouse models have long been used as valuable in vivo platforms to investigate the pathogenesis of viral infections and effective countermeasures. The natural resistance of mice to the novel betacoronavirus SARS-CoV-2, the causative agent of COVID-19, has launched a race toward the characterization of SARS-CoV-2 infection in other animals (e.g., hamsters, cats, ferrets, bats, and monkeys), as well as adaptation of the mouse model, by modifying either the host or the virus. In the present study, we utilized a natural pathogen of mice, MHV, as a prototype to model betacoronavirus-induced acute lung injure and multiorgan involvement under biosafety level 2 conditions. We showed that C57BL/6J mice intranasally inoculated with MHV-3 develops severe disease, which includes acute lung damage and respiratory distress that precede systemic inflammation and death. Accordingly, the proposed animal model may provide a useful tool for studies regarding betacoronavirus respiratory infection and related diseases.

Abnormal Airway Mucus Secretion Induced by Virus Infection

The airway mucus barrier is a primary defensive layer at the airway surface. Mucins are the major structural components of airway mucus that protect the respiratory tract. Respiratory viruses invade human airways and often induce abnormal mucin overproduction and airway mucus secretion, leading to airway obstruction and disease. The mechanism underlying the virus-induced abnormal airway mucus secretion has not been fully studied so far. Understanding the mechanisms by which viruses induce airway mucus hypersecretion may open new avenues to treatment. In this article, we elaborate the clinical and experimental evidence that respiratory viruses cause abnormal airway mucus secretion, review the underlying mechanisms, and also discuss the current research advance as well as potential strategies to treat the abnormal airway mucus secretion caused by SARS-CoV-2.

Indirect-Acting Pan-Antivirals vs. Respiratory Viruses: A Fresh Perspective on Computational Multi-Target Drug Discovery

Respiratory viruses continue to afflict mankind. Among them, pathogens such as coronaviruses [including the current pandemic agent known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)] and the one causing influenza A (IAV) are highly contagious and deadly. These can evade the immune system defenses while causing a hyperinflammatory response that can damage different tissues/organs. Simultaneously targeting immunomodulatory proteins is a plausible antiviral strategy since it could lead to the discovery of indirect-acting pan-antiviral (IAPA) agents for the treatment of diseases caused by respiratory viruses. In this context, computational approaches, which are an essential part of the modern drug discovery campaigns, could accelerate the identification of multi-target immunomodulators. This perspective discusses the usefulness of computational multi-target drug discovery for the virtual screening (drug repurposing) of IAPA agents capable of boosting the immune system through the activation of the toll-like receptor 7 (TLR7) and/or the stimulator of interferon genes (STING) while inhibiting key pro-inflammatory proteins, such as caspase-1 and tumor necrosis factor-alpha (TNF-α).

The role of influenza A virus-induced hypercytokinemia

Influenza viruses are one of the leading causes of respiratory tract infections in humans and their newly emerging and re-emerging virus strains are responsible for seasonal epidemics and occasional pandemics, leading to a serious threat to global public health systems. The poor clinical outcome and pathogenesis during influenza virus infection in humans and animal models are often associated with elevated proinflammatory cytokines and chemokines production, which is also known as hypercytokinemia or "cytokine storm", that precedes acute respiratory distress syndrome (ARDS) and often leads to death. Although we still do not fully understand the complex nature of cytokine storms, the use of immunomodulatory drugs is a promising approach for treating hypercytokinemia induced by an acute viral infection, including highly pathogenic avian influenza virus infection and Coronavirus Disease 2019 (COVID-19). This review aims to discuss the immune responses and cytokine storm pathology induced by influenza virus infection and also summarize alternative experimental strategies for treating hypercytokinemia caused by influenza virus.

The cytokine storms of COVID-19, H1N1 influenza, CRS and MAS compared. Can one sized treatment fit all?

An analysis of published data appertaining to the cytokine storms of COVID-19, H1N1 influenza, cytokine release syndrome (CRS), and macrophage activation syndrome (MAS) reveals many common immunological and biochemical abnormalities. These include evidence of a hyperactive coagulation system with elevated D-dimer and ferritin levels, disseminated intravascular coagulopathy (DIC) and microthrombi coupled with an activated and highly permeable vascular endothelium. Common immune abnormalities include progressive hypercytokinemia with elevated levels of TNF-α, interleukin (IL)-6, and IL-1β, proinflammatory chemokines, activated macrophages and increased levels of nuclear factor kappa beta (NFκB). Inflammasome activation and release of damage associated molecular patterns (DAMPs) is common to COVID-19, H1N1, and MAS but does not appear to be a feature of CRS. Elevated levels of IL-18 are detected in patients with COVID-19 and MAS but have not been reported in patients with H1N1 influenza and CRS. Elevated interferon-γ is common to H1N1, MAS, and CRS but levels of this molecule appear to be depressed in patients with COVID-19. CD4+ T, CD8+ and NK lymphocytes are involved in the pathophysiology of CRS, MAS, and possibly H1N1 but are reduced in number and dysfunctional in COVID-19. Additional elements underpinning the pathophysiology of cytokine storms include Inflammasome activity and DAMPs. Treatment with anakinra may theoretically offer an avenue to positively manipulate the range of biochemical and immune abnormalities reported in COVID-19 and thought to underpin the pathophysiology of cytokine storms beyond those manipulated via the use of, canakinumab, Jak inhibitors or tocilizumab. Thus, despite the relative success of tocilizumab in reducing mortality in COVID-19 patients already on dexamethasone and promising results with Baricitinib, the combination of anakinra in combination with dexamethasone offers the theoretical prospect of further improvements in patient survival. However, there is currently an absence of trial of evidence in favour or contravening this proposition. Accordingly, a large well powered blinded prospective randomised controlled trial (RCT) to test this hypothesis is recommended.

The Influence of Corticosteroids, Immunosuppressants and Biologics on Patients With Inflammatory Bowel Diseases, Psoriasis and Rheumatic Diseases in the Era of COVID-19: A Review of Current Evidence

Patients with inflammatory bowel disease, psoriasis or other rheumatic diseases treated with corticosteroids, immunomodulators and biologics might face additional risk during COVID-19 epidemic due to their immunocompromised status. However, there was still no unanimous opinion on the use of these therapy during COVID-19 epidemic. Current studies suggested that systemic corticosteroids might increase the risk of hospitalization, as well as risks of ventilation, ICU, and death among patients with immune-mediated inflammatory diseases. Anti-TNF agent was associated with lower rate of hospitalization, as well as lower risks of ventilation, ICU, and death. No significant changes in rates of hospitalization, ventilation, ICU and mortality were observed in patients treated with immunomodulators or biologics apart from anti-TNF agents. The underlying mechanism of these results might be related to pathway of antiviral immune response and cytokine storm induced by SARS-COV-2 infection. Decision on the use of corticosteroids, immunomodulators and biologics should be made after weighing the benefits and potential risks based on individual patients.

Rapid and sustained decline in CXCL-10 (IP-10) annotates clinical outcomes following TNFα-antagonist therapy in hospitalized patients with severe and critical COVID-19 respiratory failure

BACKGROUND

A feedforward pathological signaling loop generated by TNFα and IFN-γ synergy in the inflamed lung, driving CXCL-10 (IP-10) and CXCL-9 chemokine-mediated activated T-cell and monocyte/macrophage tissue recruitment, may define the inflammatory biology of lethal COVID-19 respiratory failure.

METHODS

To assess TNFα-antagonist therapy, 18 hospitalized adults with hypoxic respiratory failure and COVID-19 pneumonia received single-dose infliximab-abda therapy 5 mg/kg intravenously between April and December 2020. The primary endpoint was time to increase in oxygen saturation to fraction of inspired oxygen ratio (SpO2/FiO2) by ≥50 compared to baseline and sustained for 48 h. Secondary endpoints included 28-day mortality, dynamic cytokine profiles, secondary infections, duration of supplemental oxygen support, and hospitalization.

FINDINGS

Patients were predominantly in critical respiratory failure (15/18, 83%), male (14/18, 78%), above 60 years (median 63 years, range 31-80), race-ethnic minorities (13/18, 72%), lymphopenic (13/18, 72%), steroid-treated (17/18, 94%), with a median ferritin of 1953 ng/ml. Sixteen patients (89%) met the primary endpoint within a median of 4 days; 14/18 (78%) were discharged in a median of 8 days and were alive at 28-day follow-up. Three deaths were attributed to secondary lung infection. Mean plasma IP-10 levels declined sharply from 9183 to 483 pg/ml at Day 3 and 146 pg/ml at Day 14/discharge. Significant Day 3 declines in IFN-, TNFα, IL-27, CRP, and ferritin occurred. IP-10 and CXCL-9 declines were strongly correlated among patients with lymphopenia reversal (Day 3, Pearson r: 0.98, P-value 0.0006).

INTERPRETATION

Infliximab-abda may rapidly abrogate pathological inflammatory signaling to facilitate clinical recovery in severe and critical COVID-19.

Rapid and sustained decline in CXCL-10 (IP-10) annotates clinical outcomes following TNF-α antagonist therapy in hospitalized patients with severe and critical COVID-19 respiratory failure

Background

A feed-forward pathological signaling loop generated by TNFα and IFN-γ in inflamed lung tissue, driving CXCL-10 (IP-10) and CXCL-9 chemokine-mediated activated T-cell and monocyte/macrophage tissue recruitment, may define, sustain and amplify the inflammatory biology of lethal COVID-19 respiratory failure.

Methods

To assess TNFα-antagonist therapy, 18 hospitalized adults with hypoxic respiratory failure and COVID-19 pneumonia received single-dose infliximab-abda therapy 5mg/kg intravenously between April and December 2020. The primary endpoint was time to increase in oxygen saturation to fraction of inspired oxygen ratio (SpO2/FiO2) by ≥ 50 compared to baseline and sustained for 48 hours. Secondary endpoints included 28-day mortality, dynamic cytokine profiles (Human Cytokine 48-Plex Discovery Assay, Eve Technologies), secondary infections, duration of supplemental oxygen support and hospitalization.

Findings

Patients were predominantly in critical respiratory failure (15/18, 83%), male (14/18, 78%), above 60 years (median 63 yrs, range 31-80), race-ethnic minorities (13/18, 72%), lymphopenic (13/18, 72%), steroid-treated (17/18, 94%), with a median ferritin of 1953ng/ml. Sixteen patients (89%) met the primary endpoint within a median of 4 days, 15/18 (83%) recovered from respiratory failure, and 14/18 (78%) were discharged in a median of 8 days and were alive at 28-day follow-up. Deaths among three patients ≥ 65yrs age with pre-existing lung disease or multiple comorbidities were attributed to secondary lung infection. Mean plasma IP-10 levels declined sharply from 9183 pg/ml to 483 pg/ml at Day 3 and further to 146 pg/ml at Day 14/discharge. Significant declines in IFN- γ , TNFα, IL-27, CRP and ferritin were specifically observed at Day 3 whereas other cytokines were unmodified. IL-6 levels declined sharply among patients with baseline levels >10 pg/ml. Among 13 lymphopenic patients, six (46%) had resolution of lymphopenia by day 3, and 11 by day 14. CXCR3-ligand (IP-10 and CXCL-9) declines were strongly correlated among patients with lymphopenia reversal (Day 3, Pearson r: 0.98, p-value: 0.0006).

Interpretation

Consistent with a pathophysiological role of TNFα, the clinical and cytokine data indicate that infliximab-abda may rapidly abrogate pathological inflammatory signaling to facilitate clinical recovery in severe and critical COVID-19. Randomized studies are required to formally assess mortality outcomes. Funding: National Center for Advancing Translational Sciences.

Etanercept Protected Against Cigarette Smoke Extract-Induced Inflammation and Apoptosis of Human Pulmonary Artery Endothelial Cells via Regulating TNFR1

Purpose

Etanercept (ETN), a tumor necrosis factor-α (TNF-α) inhibitor, has been applied in the treatment of many diseases. However, whether it has effects on chronic obstructive pulmonary disease (COPD) and its interaction with tumor necrosis factor receptor 1 (TNFR1) remained unknown.

Methods

Histopathological analysis of lung tissues from non-smokers and smokers with or without COPD was conducted using hematoxylin–eosin (H&E) staining, Van Gieson (VG) staining, and terminal transferase-mediated biotin dUTP nick end labeling (TUNEL). TNF-α content was measured using Immunohistochemistry. Correlation analysis among apoptosis rate, smoke index, the FEV1/FVC ratio, and TNF-α-positive cells was performed. After ETN treatment and transfection of overexpressed or silenced TNFR1, levels of inflammatory cytokines, apoptosis and related genes expressions in cigarette smoke extract (CSE)-treated human pulmonary artery endothelial cells (HPAECs) were detected using enzyme-linked immunosorbent assay (ELISA), Hoechst 33342 staining, flow cytometry, quantitative real-time PCR (qRT-PCR) and Western blot.

Results

Pulmonary arterial remodeling and increased apoptotic and TNF-α⁺ HPAECs were found in lung tissue of smokers with or without COPD, with higher degrees in smokers with COPD. The numbers of apoptotic and TNF-α⁺ HPAECs were positively correlated with smoke index, while the FEV1/FVC ratio was negatively correlated with apoptotic HPAECs. In HPAECs, ETN downregulated the expressions of proteins related to CSE-induced apoptosis and the TNF receptor family, decreased CSE-induced cell apoptosis and inflammatory cytokine levels, and inhibited TNFR1 expression and p65 phosphorylation. Overexpressed TNFR1 reversed the effects of ETN on CSE-treated HPAECs, whereas silencing TNFR1 did the opposite.

Conclusion

ETN protected HPAECs against CSE-induced inflammation and apoptosis via downregulating TNFR1, thus providing a potential therapy for smoking-induced COPD.

Potential Effects of Melatonin and Micronutrients on Mitochondrial Dysfunction during a Cytokine Storm Typical of Oxidative/Inflammatory Diseases

Exaggerated oxidative stress and hyper-inflammation are essential features of oxidative/inflammatory diseases. Simultaneously, both processes may be the cause or consequence of mitochondrial dysfunction, thus establishing a vicious cycle among these three factors. However, several natural substances, including melatonin and micronutrients, may prevent or attenuate mitochondrial damage and may preserve an optimal state of health by managing the general oxidative and inflammatory status. This review aims to describe the crucial role of mitochondria in the development and progression of multiple diseases as well as the close relationship among mitochondrial dysfunction, oxidative stress, and cytokine storm. Likewise, it attempts to summarize the main findings related to the powerful effects of melatonin and some micronutrients (vitamins and minerals), which may be useful (alone or in combination) as therapeutic agents in the treatment of several examples of oxidative/inflammatory pathologies, including sepsis, as well as cardiovascular, renal, neurodegenerative, and metabolic disorders.

Virulent African horse sickness virus serotype 4 interferes with the innate immune response in horse peripheral blood mononuclear cells in vitro

African horse sickness (AHS) is caused by African horse sickness virus (AHSV), a double stranded RNA (dsRNA) virus of the genus Orbivirus, family Reoviridae. For the development of new generation AHS vaccines or antiviral treatments, it is crucial to understand the host immune response against the virus and the immune evasion strategies the virus employs. To achieve this, the current study used transcriptome analysis of RNA sequences to characterize and compare the innate immune responses activated during the attenuated AHSV serotype 4 (attAHSV4) (in vivo) and the virulent AHSV4 (virAHSV4) (in vitro) primary and secondary immune responses in horse peripheral blood mononuclear cells (PBMC) after 24 h. The pro-inflammatory cytokine and chemokine responses were negatively regulated by anti-inflammatory cytokines, whereas the parallel type I and type III IFN responses were maintained downstream of nucleic acid sensing pattern recognition receptor (PRR) signalling pathways during the attAHSV4 primary and secondary immune responses. It appeared that after translation, virAHSV4 proteins were able to interfere with the C-terminal IRF association domain (IAD)-type 1 (IAD1) containing IRFs, which inhibited the expression of type I and type III IFNs downstream of PRR signalling during the virAHSV4 primary and secondary immune responses. Viral interference resulted in an impaired innate immune response that was not able to eliminate virAHSV4-infected PBMC and gave rise to prolonged expression of pro-inflammatory cytokines and chemokines during the virAHSV4 induced primary immune response. Indicating that virAHSV4 interference with the innate immune response may give rise to an excessive inflammatory response that causes immunopathology, which could be a major contributing factor to the pathogenesis of AHS in a naïve horse. Viral interference was overcome by the fast kinetics and increased effector responses of innate immune cells due to trained innate immunity and memory T cells and B cells during the virAHSV4 secondary immune response.

The effects of novel coronavirus (SARS-CoV-2) infection on cardiovascular diseases and cardiopulmonary injuries

COVID-19 caused by a novel coronavirus named SARS-CoV-2, can elites severe acute respiratory syndrome, severe lung injury, cardiac injury, and even death and became a worldwide pandemic. SARS-CoV-2 infection may result in cardiac injury via several mechanisms, including the expression of angiotensin-converting enzyme 2 (ACE2) receptor and leading to a cytokine storm, can elicit an exaggerated host immune response. This response contributes to multi-organ dysfunction. As an emerging infectious disease, there are limited data on the effects of this infection on patients with underlying cardiovascular comorbidities. In this review, we summarize the early-stage clinical experiences with COVID-19, with particular focus on patients with cardiovascular diseases and cardiopulmonary injuries, and explores potential available evidence regarding the association between COVID-19, and cardiovascular complications.

Targeting tumour necrosis factor to ameliorate viral pneumonia

Pneumonia is a serious complication associated with inflammation of the lungs due to infection with viral pathogens. Seasonal and pandemic influenza viruses, variola virus (agent of smallpox) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; agent of COVID-19) are some leading examples. Viral pneumonia is triggered by excessive inflammation associated with dysregulated cytokine production, termed 'cytokine storm'. Several cytokines have been implicated but tumour necrosis factor (TNF) plays a critical role in driving lung inflammation, severe lung pathology and death. Despite this, the exact role TNF plays in the aetiology and pathogenesis of virus infection-induced respiratory complications is not well understood. In this review, we discuss the pathological and immunomodulatory roles of TNF in contributing to immunopathology and resolution of lung inflammation, respectively, in mouse models of influenza- and smallpox (mousepox)-induced pneumonia. We review studies that have investigated dampening of inflammation on the outcome of severe influenza and orthopoxvirus infections. Most studies on the influenza model have evaluated the efficacy of treatment with anti-inflammatory drugs, including anti-TNF agents, in animal models on the day of viral infection. We question the merits of those studies as they are not transferable to the clinic given that individuals generally present at a hospital only after the onset of disease symptoms and not on the day of infection. We propose that research should be directed at determining whether dampening lung inflammation after the onset of disease symptoms will reduce morbidity and mortality. Such a treatment strategy will be more relevant clinically.

Divergent Mast Cell Responses Modulate Antiviral Immunity During Influenza Virus Infection

Influenza A virus (IAV) is a respiratory pathogen that infects millions of people each year. Both seasonal and pandemic strains of IAV are capable of causing severe respiratory disease with a high risk of respiratory failure and opportunistic secondary infection. A strong inflammatory cytokine response is a hallmark of severe IAV infection. The widespread tissue damage and edema in the lung during severe influenza is largely attributed to an overexuberant production of inflammatory cytokines and cell killing by resident and infiltrating leukocytes. Mast cells (MCs) are a sentinel hematopoietic cell type situated at mucosal sites, including the lung. Poised to react immediately upon detecting infection, MCs produce a vast array of immune modulating molecules, including inflammatory cytokines, chemokines, and proteases. As such, MCs have been implicated as a source of the immunopathology observed in severe influenza. However, a growing body of evidence indicates that MCs play an essential role not only in inducing an inflammatory response but in suppressing inflammation as well. MC-derived immune suppressive cytokines are essential to the resolution of a number of viral infections and other immune insults. Absence of MCs prolongs infection, exacerbates tissue damage, and contributes to dissemination of the pathogen to other tissues. Production of cytokines such as IL-10 and IL-6 by MCs is essential for mitigating the inflammation and tissue damage caused by innate and adaptive immune cells alike. The two opposing functions of MCs—one pro-inflammatory and one anti-inflammatory—distinguish MCs as master regulators of immunity at the site of infection. Amongst the first cells to respond to infection or injury, MCs persist for the duration of the infection, modulating the recruitment, activation, and eventual suppression of other immune cells. In this review, we will discuss the immune modulatory roles of MCs over the course of viral infection and propose that the immune suppressive mediators produced by MCs are vital to minimizing immunopathology during influenza infection.

Attenuation of acute and chronic inflammation using compounds derived from plants

The appearance of excessive inflammatory activity is associated with onset of many disease states. Such non-productive responses are often the basis of the mortality consequent to incurring numerous disorders. The current outbreak of coronavirus disease 2019 caused by the virus "severe acute respiratory syndrome coronavirus 2" is a striking reflection of the inadequacy of current medical science to adequately address this issue. The usefulness of a range of materials of botanical origin in the attenuation of both chronic and acute inflammatory responses to various disease stressors is described. The properties of preparations of plant-based origin often parallel those of synthesized pharmacologics, but differ from them in some key respects. These differences can lead to more traditional preparations having distinct therapeutic advantages but also a number of specific shortcomings. The strengths and weaknesses of these materials are objectively contrasted with that of a more orthodox pharmacological approach. Each of these emphases in style has specific advantages and they should not be considered as competitors, but rather as accomplices in combating adverse states involving derangement of immune function.

Genetic Dissection of the Regulatory Mechanisms of Ace2 in the Infected Mouse Lung

Acute lung injury (ALI) is an important cause of morbidity and mortality after viral infections, including influenza A virus H1N1, SARS-CoV, MERS-CoV, and SARS-CoV-2. The angiotensin I converting enzyme 2 (ACE2) is a key host membrane-bound protein that modulates ALI induced by viral infection, pulmonary acid aspiration, and sepsis. However, the contributions of ACE2 sequence variants to individual differences in disease risk and severity after viral infection are not understood. In this study, we quantified H1N1 influenza-infected lung transcriptomes across a family of 41 BXD recombinant inbred strains of mice and both parents—C57BL/6J and DBA/2J. In response to infection Ace2 mRNA levels decreased significantly for both parental strains and the expression levels was associated with disease severity (body weight loss) and viral load (expression levels of viral NA segment) across the BXD family members. Pulmonary RNA-seq for 43 lines was analyzed using weighted gene co-expression network analysis (WGCNA) and Bayesian network approaches. Ace2 not only participated in virus-induced ALI by interacting with TNF, MAPK, and NOTCH signaling pathways, but was also linked with high confidence to gene products that have important functions in the pulmonary epithelium, including Rnf128, Muc5b, and Tmprss2. Comparable sets of transcripts were also highlighted in parallel studies of human SARS-CoV-infected primary human airway epithelial cells. Using conventional mapping methods, we determined that weight loss at two and three days after viral infection maps to chromosome X—the location of Ace2. This finding motivated the hierarchical Bayesian network analysis, which defined molecular endophenotypes of lung infection linked to Ace2 expression and to a key disease outcome. Core members of this Bayesian network include Ace2, Atf4, Csf2, Cxcl2, Lif, Maml3, Muc5b, Reg3g, Ripk3, and Traf3. Collectively, these findings define a causally-rooted Ace2 modulatory network relevant to host response to viral infection and identify potential therapeutic targets for virus-induced respiratory diseases, including those caused by influenza and coronaviruses.

Anti-Influenza Drug Discovery and Development: Targeting the Virus and Its Host by All Possible Means

Infections by influenza virus constitute a major and recurrent threat for human health. Together with vaccines, antiviral drugs play a key role in the prevention and treatment of influenza virus infection and disease. Today, the number of antiviral molecules approved for the treatment of influenza is relatively limited, and their use is threatened by the emergence of viral strains with resistance mutations. There is therefore a real need to expand the prophylactic and therapeutic arsenal. This chapter summarizes the state of the art in drug discovery and development for the treatment of influenza virus infections, with a focus on both virus-targeting and host cell-targeting strategies. Novel antiviral strategies targeting other viral proteins or targeting the host cell, some of which are based on drug repurposing, may be used in combination to strengthen our therapeutic arsenal against this major pathogen.

Background to new treatments for COVID-19, including its chronicity, through altering elements of the cytokine storm

Anti-tumour necrosis factor (TNF) biologicals, Dexamethasone and rIL-7 are of considerable interest in treating COVID-19 patients who are in danger of, or have become, seriously ill. Yet reducing sepsis mortality by lowering circulating levels of TNF lost favour when positive endpoints in earlier simplistic models could not be reproduced in well-conducted human trials. Newer information with anti-TNF biologicals has encouraged reintroducing this concept for treating COVID-19. Viral models have had encouraging outcomes, as have the effects of anti-TNF biologicals on community-acquired COVID-19 during their long-term use to treat chronic inflammatory states. The positive outcome of a large scale trial of dexamethasone, and its higher potency late in the disease, harmonises well with its capacity to enhance levels of IL-7Rα, the receptor for IL-7, a cytokine that enhances lymphocyte development and is increased during the cytokine storm. Lymphoid germinal centres required for antibody-based immunity can be harmed by TNF, and restored by reducing TNF. Thus the IL-7- enhancing activity of dexamethasone may explain its higher potency when lymphocytes are depleted later in the infection, while employing anti-TNF, for several reasons, is much more logical earlier in the infection. This implies dexamethasone could prove to be synergistic with rIL-7, currently being trialed as a COVID-19 therapeutic. The principles behind these COVID-19 therapies are consistent with the observed chronic hypoxia through reduced mitochondrial function, and also the increased severity of this disease in ApoE4-positive individuals. Many of the debilitating persistent aspects of this disease are predictably susceptible to treatment with perispinal etanercept, since they have cerebral origins.

COVID-19 and NSAIDS: A Narrative Review of Knowns and Unknowns

Concern about the appropriate role of nonsteroidal anti-inflammatory drugs (NSAIDs) in COVID-19 speculate that NSAIDs, in particular ibuprofen, may upregulate the entry point for the virus, the angiotensin-converting enzyme (ACE) 2 receptors and increase susceptibility to the virus or worsen symptoms in existing disease. Adverse outcomes with COVID-19 have been linked to cytokine storm but the most effective way to address exaggerated inflammatory response is complex and unclear. The Expert Working Group on the Commission of Human Medicines in the UK and other organizations have stated that there is insufficient evidence to establish a link between ibuprofen and susceptibility to or exacerbation of COVID-19. NSAID use must also be categorized by whether the drugs are relatively low-dose over-the-counter oral products taken occasionally versus higher-dose or parenteral NSAIDs. Even if evidence emerged arguing for or against NSAIDs in this setting, it is unclear if this evidence would apply to all NSAIDs at all doses in all dosing regimens. Paracetamol (acetaminophen) has been proposed as an alternative to NSAIDs but there are issues with liver toxicity at high doses. There are clearly COVID-19 cases where NSAIDs should not be used, but there is no strong evidence that NSAIDs must be avoided in all patients with COVID-19; clinicians must weigh these choices on an individual basis.

The treatment of SARS-CoV2 with antivirals and mitigation of the cytokine storm syndrome: the role of gene expression

In the absence of a vaccine, the treatment of SARS-CoV2 has focused on eliminating the virus with antivirals or mitigating the cytokine storm syndrome (CSS) that leads to the most common cause of death: respiratory failure. Herein we discuss the mechanisms of antiviral treatments for SARS-CoV2 and treatment strategies for the CSS. Antivirals that have shown in vitro activity against SARS-CoV2, or the closely related SARS-CoV1 and MERS-CoV, are compared on the enzymatic level and by potency in cells. For treatment of the CSS, we discuss medications that reduce the effects or expression of cytokines involved in the CSS with an emphasis on those that reduce IL-6 because of its central role in the development of the CSS. We show that some of the medications covered influence the activity or expression of enzymes involved in epigenetic processes and specifically those that add or remove modifications to histones or DNA. Where available, the latest clinical data showing the efficacy of the medications is presented. With respect to their mechanisms, we explain why some medications are successful, why others have failed, and why some untested medications may yet prove useful.

Regeneration of the pulmonary vascular endothelium after viral pneumonia requires COUP-TF2

Acute respiratory distress syndrome is associated with a robust inflammatory response that damages the vascular endothelium, impairing gas exchange. While restoration of microcapillaries is critical to avoid mortality, therapeutic targeting of this process requires a greater understanding of endothelial repair mechanisms. Here, we demonstrate that lung endothelium possesses substantial regenerative capacity and lineage tracing reveals that native endothelium is the source of vascular repair after influenza injury. Ablation of chicken ovalbumin upstream promoter-transcription factor 2 (COUP-TF2) (Nr2f2), a transcription factor implicated in developmental angiogenesis, reduced endothelial proliferation, exacerbating viral lung injury in vivo. In vitro, COUP-TF2 regulates proliferation and migration through activation of cyclin D1 and neuropilin 1. Upon influenza injury, nuclear factor κB suppresses COUP-TF2, but surviving endothelial cells ultimately reestablish vascular homeostasis dependent on restoration of COUP-TF2. Therefore, stabilization of COUP-TF2 may represent a therapeutic strategy to enhance recovery from pathogens, including H1N1 influenza and SARS-CoV-2.

Baicalin down-regulating hepatitis B virus transcription depends on the liver-specific HNF4α-HNF1α axis

Baicalin (BA) inhibits hepatitis B virus (HBV) RNAs production and reduces levels of the related hepatocyte nuclear factors (HNFs), although the underlying mechanism is unclear. In this study, we investigated the specific pathway by which BA regulates HBV transcription through the HBV-related HNFs. Following transfection of HepG2 cells with pHBV1.2, we observed that BA inhibited the production of HBV RNAs and viral proteins in a time- and dose-dependent manner. These effects were consistent with the downregulation of HNF1α, which was abolished by HNF1α-shRNA. The shRNA of HNF4α, the upstream gene of HNF1α, also remarkedly reduced HNF1α expression and impaired the anti-HBV efficacy of BA, indicating that this function of BA depended on HNF4α/HNF1α axis. Furthermore, chromatin immunoprecipitation assay showed that BA significantly reduced HNF4α-HNF1α transactivation activity. The similar effects of BA were observed in entecavir (ETV)-resistant HBV^{rtM204V/rtLl80M} transfected HepG2 cells. Thus, we proposed a mechanism for the anti-HBV activity of BA in an HNF4α-HNF1α-dependent manner, which impaired HNF4α and HNF1α transactivation, and effectively inhibited HBV transcription and viral replication.

COVID-19: A collision of complement, coagulation and inflammatory pathways

COVID-19 is frequently accompanied by a hypercoagulable inflammatory state with microangiopathic pulmonary changes that can precede the diffuse alveolar damage characteristic of typical acute respiratory distress syndrome (ARDS) seen in other severe pathogenic infections. Parallels with systemic inflammatory disorders such as atypical hemolytic uremic syndrome (aHUS) have implicated the complement pathway in the pathogenesis of COVID-19, and particularly the anaphylatoxins C3a and C5a released from cleavage of C3 and C5, respectively. C5a is a potent cell signalling protein that activates a cytokine storm-a hyper-inflammatory phenomenon-within hours of infection and the innate immune response. However, excess C5a can result in a pro-inflammatory environment orchestrated through a plethora of mechanisms that propagate lung injury, lymphocyte exhaustion, and an immune paresis. Furthermore, disruption of the homeostatic interactions between complement and extrinsic and intrinsic coagulation pathways contributes to a net pro-coagulant state in the microvasculature of critical organs. Fatal COVID-19 has been associated with a systemic inflammatory response accompanied by a pro-coagulant state and organ damage, particularly microvascular thrombi in the lungs and kidneys. Pathologic studies report strong evidence of complement activation. C5 blockade reduces inflammatory cytokines and their manifestations in animal studies, and has shown benefits in patients with aHUS, prompting investigation of this approach in the treatment of COVID-19. This review describes the role of the complement pathway and particularly C5a and its aberrations in highly pathogenic virus infections, and therefore its potential as a therapeutic target in COVID-19.

Identifying Active Compounds and Targets of Fritillariae thunbergii against Influenza-Associated Inflammation by Network Pharmacology Analysis and Molecular Docking

Complications due to influenza are often associated with inflammation with excessive release of cytokines. The bulbs of Fritillariae thunbergii (FT) have been traditionally used to control airway inflammatory diseases, such as bronchitis and pneumonia. To elucidate active compounds, the targets, and underlying mechanisms of FT for the treatment of influenza-induced inflammation, systems biology was employed. Active compounds of FT were identified through the TCMSP database according to oral bioavailability (OB) and drug-likeness (DL) criteria. Other pharmacokinetic parameters, Caco-2 permeability (Caco-2), and drug half-life (HL) were also identified. Biological targets of FT were retrieved from DrugBank and STITCH databases, and target genes associated with influenza, lung, and spleen inflammation were collected from DisGeNET and NCBI databases. Compound-disease-target (C-D-T) networks were constructed and merged using Cytoscape. Target genes retrieved from the C-D-T network were further analyzed with GO enrichment and KEGG pathway analysis. In our network, GO and KEGG results yielded two compounds (beta-sitosterol (BS) and pelargonidin (PG)), targets (PTGS1 (COX-1) and PTGS2 (COX-2)), and pathways (nitric oxide, TNF) were involved in the inhibitory effects of FT on influenza-associated inflammation. We retrieved the binding affinity of each ligand-target, and found that PG and COX-1 showed the strongest binding affinity among four binding results using a molecular docking method. We identified the potential compounds and targets of FT against influenza and suggest that FT is an immunomodulatory therapy for influenza-associated inflammation.

Dynamic Natural Killer Cell and T Cell Responses to Influenza Infection

Influenza viruses have perplexed scientists for over a hundred years. Yearly vaccines limit their spread, but they do not prevent all infections. Therapeutic treatments for those experiencing severe infection are limited; further advances are held back by insufficient understanding of the fundamental immune mechanisms responsible for immunopathology. NK cells and T cells are essential in host responses to influenza infection. They produce immunomodulatory cytokines and mediate the cytotoxic response to infection. An imbalance in NK and T cell responses can lead to two outcomes: excessive inflammation and tissue damage or insufficient anti-viral functions and uncontrolled infection. The main cause of death in influenza patients is the former, mediated by hyperinflammatory responses termed “cytokine storm.” NK cells and T cells contribute to cytokine storm, but they are also required for viral clearance. Many studies have attempted to distinguish protective and pathogenic components of the NK cell and T cell influenza response, but it has become clear that they are dynamic and integrated processes. This review will analyze how NK cell and T cell effector functions during influenza infection affect the host response and correlate with morbidity and mortality outcomes.

Severe Acute Respiratory Syndrome Coronavirus 2 and the Use of Biologics in Patients With Psoriasis [Formula: see text]

Coronavirus disease (COVID-19), a respiratory disease caused by a novel coronavirus designated severe acute respiratory syndrome coronavirus 2, has rapidly spread worldwide and has been recognized as a pandemic by the World Health Organization. Patients with altered immunologic function are at higher risk of acquiring COVID-19. In patients with psoriasis, inhibition of select pro-inflammatory cytokines through the use of biologic agents has been shown to be an effective treatment option. Pro-inflammatory cytokines have key immunomodulatory effects and are known to be involved in the hosts' immune response to a variety of viral infections. Though little is currently known about the role of inflammatory cytokines in COVID-19, early reports have shown patients with severe disease to have elevated serum levels of select inflammatory cytokines such as tumor necrosis factor alpha. This review will summarize key information that is currently known about COVID-19, the role of select cytokines in viral defense, and important considerations for patients with psoriasis using biologic agents during this pandemic. Currently, there is insufficient evidence to discontinue biologic therapy in patients with psoriasis who have not tested positive for COVID-19. The decision to pause biologic therapy should be considered on a case-by-case basis in patients in higher risk populations, and should take into account individual risk and benefit. Until more is known about the impact of biologic therapy on COVID-19 outcomes, we recommend patients with psoriasis who test positive for COVID-19 be instructed to discontinue or postpone biologic treatment until they have recovered from infection.

Mild COVID-19 Symptoms in an Infliximab-Treated Ulcerative Colitis Patient: Can Ongoing Anti-TNF Therapy Protect against the Viral Hyperinflammatory Response and Avoid Aggravated Outcomes?

The ongoing coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2, represents a potentially major challenge to patients with immune-mediated inflammatory diseases who are treated with immunomodulatory therapies. We report the case of an 18-year-old ulcerative colitis patient in sustained clinical remission who 4 days after application of her ongoing therapy with the anti-TNF antibody infliximab developed mild respiratory and abdominal symptoms. The patient was subsequently diagnosed with COVID-19 but did not need hospitalization. The clinical symptoms completely resolved within 1 week after onset and there was no change in ulcerative colitis activity. The recently applied anti-TNF therapy did not lead to exacerbation of the infectious symptoms. Current recommendations strongly favor continuation of effective maintenance anti-TNF therapy in inflammatory bowel disease patients, as there is no evidence for aggravated CO-VID-19 upon infection. It is unclear whether anti-TNF treatment might even have assisted in preventing worsening of COVID-19 and improving outcome. Further data in the group of immune-mediated inflammatory disease patients under anti-TNF therapy are urgently needed.