The Many Ways to Deal with STING.

The stimulator of interferon genes (STING) is an adaptor protein involved in the activation of IFN-ß and many other genes associated with the immune response activation in vertebrates. STING induction has gained attention from different angles such as the potential to trigger an early immune response against different signs of infection and cell damage, or to be used as an adjuvant in cancer immune treatments. Pharmacological control of aberrant STING activation can be used to mitigate the pathology of some autoimmune diseases. The STING structure has a well-defined ligand binding site that can harbor natural ligands such as specific purine cyclic di-nucleotides (CDN). In addition to a canonical stimulation by CDNs, other non-canonical stimuli have also been described, whose exact mechanism has not been well defined. Understanding the molecular insights underlying the activation of STING is important to realize the different angles that need to be considered when designing new STING-binding molecules as therapeutic drugs since STING acts as a versatile platform for immune modulators. This review analyzes the different determinants of STING regulation from the structural, molecular, and cell biology points of view.

Oncolytic Virotherapy in Glioma Tumors.

Glioma tumors are one of the most devastating cancer types. Glioblastoma is the most advanced stage with the worst prognosis. Current therapies are still unable to provide an effective cure. Recent advances in oncolytic immunotherapy have generated great expectations in the cancer therapy field. The use of oncolytic viruses (OVs) in cancer treatment is one such immune-related therapeutic alternative. OVs have a double oncolytic action by both directly destroying the cancer cells and stimulating a tumor specific immune response to return the ability of tumors to escape the control of the immune system. OVs are one promising alternative to conventional therapies in glioma tumor treatment. Several clinical trials have proven the feasibility of using some viruses to specifically infect tumors, eluding undesired toxic effects in the patient. Here, we revisited the literature to describe the main OVs proposed up to the present moment as therapeutic alternatives in order to destroy glioma cells in vitro and trigger tumor destruction in vivo. Oncolytic viruses were divided with respect to the genome in DNA and RNA viruses. Here, we highlight the results obtained in various clinical trials, which are exploring the use of these agents as an alternative where other approaches provide limited hope.

Influenza A virus infection alters the resistance profile of gut microbiota to clinically relevant antibiotics.

IMPORTANCE: Influenza virus infection affects both lung and intestinal bacterial community composition. Most of the published analyses focus on the characterization of the microbiota composition changes. Here we assess functional alterations of gut microbiota such as nutrient and antibiotic resistance changes during an acute respiratory tract infection. Upon influenza A virus (IAV) infection, cecal microbiota drops accompanied by a decrease in the ability to metabolize some common nutrients under aerobic conditions. At the same time, the cecal community presents an increase in resistance against clinically relevant antibiotics, particularly cephalosporins. Functional characterization of complex communities presents an additional and necessary element of analysis that nowadays is mainly limited to taxonomic description. The consequences of these functional alterations could affect treatment strategies, especially in multimicrobial infections.

Oncolytic virotherapy in lung cancer.

Lung tumors are one of the most aggressive threats affecting humans. Current therapeutic approaches have improved patients' survival; however, further efforts are required to increase effectiveness and protection against tumor relapse and metastasis. Immunotherapy presents an alternative to previous treatments that focuses on stimulating of the patient's immune system to destroy tumor cells. Viruses can be used as part of the immune therapeutic approach as agents that could selectively infect tumor cells, triggering an immune response against the infection and against the tumor cells. Some viruses have been selected for specifically infecting and destroying cancer cells, activating the immune response, enhancing access, amplifying the cytotoxicity against the tumor cells, and improving the long-term memory that can prevent tumor relapse. Oncolytic virotherapy can then be used as a strategy to target the destruction of transformed cells at the tumor site and act in locations distant from the primary targeted tumor site. Some of the current challenges in lung cancer treatment can be addressed using traditional therapies combined with oncolytic virotherapy. Defining the best combination, including the choice of the right settings will be at the next frontier in lung cancer treatment.

Determinants of poor clinical outcome in patients with influenza pneumonia: A systematic review and meta-analysis.

BACKGROUND: The clinical burden of influenza is increasing worldwide. Aging, immunosuppression, and underlying respiratory illness are determinants of poor clinical outcomes, including greater mortality. Bacterial infections seem to be the main reason. Updated information on the role of bacterial infection as the cause of complications would be of value in improving the prognosis of patients with influenza. METHODS: A systematic review and meta-analysis were performed by using the PubMed repository using keywords like: Influenza, H1N1, Streptococcus pneumoniae, bacterial coinfection, secondary coinfection, bacterial complications in pneumonia, and seasonal influenza. Only articles written in English were included in publications from 2010 to 2020. The analyses were conducted following the preferred reporting items for systematic review and meta-analyses guidelines. The results were independently validated using a TrinetX database cohort of roughly 4 million patients. RESULTS: We included 135 studies that contained data from 48,259 patients hospitalized with influenza of any age. Bacterial infections were diagnosed in 5391 (11.2%). Streptococcus pneumoniae (30.7%) and Staphylococcus aureus (30.4%) were the most frequent microorganisms, followed by Haemophilus influenzae (7.1%) and Pseudomonas aeruginosa (5.9%). The random-effects model of the meta-analysis indicated that bacterial infections posed a 3.4-fold increased risk of death compared with influenza infection alone. Unexpectedly, asthma was protective (odds ratio 0.8). CONCLUSION: Bacterial infections diagnosed in 11.2% of patients with influenza increase 3.4-fold the mortality risk. S. pneumoniae, S. aureus, H. influenzae, and P. aeruginosa account for nearly 75% of the cases. Earlier diagnosis and use of antibiotics should improve outcomes in this population.

Broad virus inactivation using inorganic micro/nano-particulate materials.

Inorganic materials can provide a set of tools to decontaminate solid, liquid or air containing viral particles. The use of disinfectants can be limited or not practical in scenarios where continuous cleaning is not feasible. Physicochemical differences between viruses raise the need for effective formulations for all kind of viruses. In the present work we describe two types of antimicrobial inorganic materials: i) a novel soda-lime glass (G3), and ii) kaolin containing metals nanoparticles (Ag or CuO), as materials to disable virus infectivity. Strong antiviral properties can be observed in G3 glass, and kaolin-containing nanoparticle materials showing a reduction of viral infectivity close to 99%. in the first 10 â€‹min of contact of vesicular stomatitis virus (VSV). A potent virucidal activity is also present in G3 and kaolin containing Ag or CuO nanoparticles against all kinds of viruses tested, reducing more than 99% the amount of HSV-1, Adenovirus, VSV, Influenza virus and SARS-CoV-2 exposed to them. Virucidal properties could be explained by a direct interaction of materials with viruses as well as inactivation by the presence of virucidal elements in the material lixiviates. Kaolin-based materials guarantee a controlled release of active nanoparticles with antiviral activity. Current coronavirus crisis highlights the need for new strategies to remove viruses from contaminated areas. We propose these low-cost inorganic materials as useful disinfecting antivirals in the actual or future pandemic threats.

Linking the Expression of Therapeutic Genes to Unfolded Protein Response: A New Option for Anti-Hepatitis B Virus Gene Therapy.

Tight control of transgene expression is key to ensure the efficacy of a wide range of gene therapy interventions, in which the magnitude and duration of gene expression have to be adjusted to therapeutic needs, thereby limiting secondary effects. The development of upgraded strategies to link transgene expression to pathological stress episodes is an unmet need in gene therapy. Here, we propose an expression strategy that associates transgene expression to an intracellular stress coping mechanism, the unfolded protein response. Specifically, we harnessed the cis elements required to sustain the noncanonical splicing of X-box binding protein 1 (XBP1) messenger RNA (mRNA) in response to the dysfunction of the endoplasmic reticulum (ER), a situation commonly known as ER stress, to drive the expression of heterologous genes. Since ER stress features a wide variety of pathological conditions, including viral infections, cancer, or metabolic disorders, this new expression module stimulates the synthesis of therapeutic genes as a response to cellular damage, and ensures their expression only when necessary. Validation of this inducible expression system was performed in vitro and in vivo, and its potential to limit/inhibit viral infections has been shown in proof-of principle experiments.

Sendai Virus, a Strong Inducer of Anti-Lentiviral State in Ovine Cells.

Small ruminant lentiviruses (SRLVs) are widely spread in the ovine and caprine populations, causing an incurable disease affecting animal health and production. Vaccine development is hindered owing to the high genetic heterogeneity of lentiviruses and the selection of T-cell and antibody escape mutants, requiring antigen delivery optimization. Sendai virus (SeV) is a respiratory paramyxovirus in mice that has been recognized as a potent inducer of innate immune responses in several species, including mouse and human. The aim of this study was to stimulate an innate antiviral response in ovine cells and evaluate the potential inhibitory effect upon small ruminant lentivirus (SRLV) infections. Ovine alveolar macrophages (AMs), blood-derived macrophages (BDMs), and skin fibroblasts (OSFs) were stimulated through infection with SeV encoding green fluorescent protein (GFP). SeV efficiently infected ovine cells, inducing an antiviral state in AM from SRLV naturally-infected animals, as well as in in vitro SRLV-infected BDM and OSF from non-infected animals. Supernatants from SeV-infected AM induced an antiviral state when transferred to fresh cells challenged with SRLV. Similar to SRLV, infectivity of an HIV-1-GFP lentiviral vector was also restricted in ovine cells infected with SeV. In myeloid cells, an M1-like proinflammatory polarization was observed together with an APOBEC3Z1 induction, among other lentiviral restriction factors. Our observations may boost new approximations in ameliorating the SRLV burden by stimulation of the innate immune response using SeV-based vaccine vectors.

Repurposing the yellow fever vaccine for intratumoral immunotherapy.

Live 17D is widely used as a prophylactic vaccine strain for yellow fever virus that induces potent neutralizing humoral and cellular immunity against the wild-type pathogen. 17D replicates and kills mouse and human tumor cell lines but not non-transformed human cells. Intratumoral injections with viable 17D markedly delay transplanted tumor progression in a CD8 T-cell-dependent manner. In mice bearing bilateral tumors in which only one is intratumorally injected, contralateral therapeutic effects are observed consistent with more prominent CD8 T-cell infiltrates and a treatment-related reduction of Tregs. Additive efficacy effects were observed upon co-treatment with intratumoral 17D and systemic anti-CD137 and anti-PD-1 immunostimulatory monoclonal antibodies. Importantly, when mice were preimmunized with 17D, intratumoral 17D treatment achieved better local and distant antitumor immunity. Such beneficial effects of prevaccination are in part explained by the potentiation of CD4 and CD8 T-cell infiltration in the treated tumor. The repurposed use of a GMP-grade vaccine to be given via the intratumoral route in prevaccinated patients constitutes a clinically feasible and safe immunotherapy approach.

Newcastle Disease Virus (NDV) Oncolytic Activity in Human Glioma Tumors Is Dependent on CDKN2A-Type I IFN Gene Cluster Codeletion.

Glioblastoma (GBM) is the most aggressive and frequent primary brain tumor in adults with a median overall survival of 15 months. Tumor recurrence and poor prognosis are related to cancer stem cells (CSCs), which drive resistance to therapies. A common characteristic in GBM is CDKN2A gene loss, located close to the cluster of type I IFN genes at Ch9p21. Newcastle disease virus (NDV) is an avian paramyxovirus with oncolytic and immunostimulatory properties that has been proposed for the treatment of GBM. We have analyzed the CDKN2A-IFN I gene cluster in 1018 glioma tumors and evaluated the NDV oncolytic effect in six GBM CSCs ex vivo and in a mouse model. Our results indicate that more than 50% of GBM patients have some IFN deletion. Moreover, GBM susceptibility to NDV is dependent on the loss of the type I IFN. Infection of GBM with an NDV-expressing influenza virus NS1 protein can overcome the resistance to oncolysis by NDV of type I-competent cells. These results highlight the potential of using NDV vectors in antitumor therapies.

Oncolytic bacteria: past, present and future.

More than a century ago, independent groups raised the possibility of using bacteria to selectively infect tumours. Such treatment induces an immune reaction that can cause tumour rejection and protect the patient against further recurrences. One of the first holistic approximations to use bacteria in cancer treatment was performed by William Coley, considered the father of immune-therapy, at the end of XIX century. Since then, many groups have used different bacteria to test their antitumour activity in animal models and patients. The basis for this reactivity implies that innate immune responses activated upon bacteria recognition, also react against the tumour. Different publications have addressed several aspects of oncolytic bacteria. In the present review, we will focus on revisiting the historical aspects using bacteria as oncolytic agents and how they led to the current clinical trials. In addition, we address the molecules present in oncolytic bacteria that induce specific toxic effects against the tumors as well as the activation of host immune responses in order to trigger antitumour immunity. Finally, we discuss future perspectives that could be considered in the different fields implicated in the implementation of this kind of therapy in order to improve the current use of bacteria as oncolytic agents.

A Digital Method to Quantify Type I Interferon.

Interferon (IFN), the first ever-described cytokine, has a potent activity against viruses. Soon since its discovery, quantification of IFN has been an important issue. Most of the traditional methods to measure IFN biological activity rely on indirect methods that quantify dyes retained by IFN-protected cells against a lytic virus, or by techniques that indirectly quantify viral replication by measuring the expression level of viral-encoded reporter proteins such as the green fluorescent protein (GFP). In both cases, the IFN units are determined by the quantification of an effective dose 50, defined as the IFN dose that prevents 50% cell death of 50% reduction of the maximal amount of GFP intensity. In this study we propose the use of an alternative approach to measure IFN activity by calculating the minimal IFN dose 50 as the amount of IFN able to completely protect 50% of the cells from infection measured by the total absence of virus-dependent GFP signal in a cell culture plate. This sensitive approach could be used to easily quantify the Z value to determine IFN bioassay robustness. We believe that this approximation could be interesting to be considered by the IFN community.

TMEM173 Alternative Spliced Isoforms Modulate Viral Replication through the STING Pathway.

The innate immune system provides a primary line of defense against pathogens. Stimulator of IFN genes (STING), encoded by the TMEM173 gene, is a critical protein involved in IFN-ß induction in response to infection by different pathogens. In this study, we describe the expression of three different alternative-spliced human (h) TMEM173 mRNAs producing STING truncated isoforms 1, 2, and 3 in addition to the full-length wild-type (wt) hSTING. All of the truncated isoforms lack exon 7 and share the N-terminal transmembrane region with wt hSTING. Overexpression of the three STING truncated isoforms failed to induce IFN-ß, and they acted as selective pathway inhibitors of wt hSTING even in combination with upstream inducer cyclic-di-GMP-AMP synthase. Truncated isoforms alter the stability of wt hSTING, reducing protein t 1/2 to some extent by the induction of proteasome-dependent degradation. Knocking down expression of truncated isoforms increased production of IFN-ß by THP1 monocytes in response to intracellular cytosolic DNA or HSV-1 infection. At early stages of infection, viruses like HSV-1 or vesicular stomatitis virus reduced the ratio of full-length wt hSTING/truncated STING isoforms, suggesting the skewing of alternative splicing of STING toward truncated forms as a tactic to evade antiviral responses. Finally, in silico analysis revealed that the human intron-exon gene architecture of TMEM173 (splice sites included) is preserved in other mammal species, predominantly primates, stressing the relevance of alternative splicing in regulating STING antiviral biology.