Pivotal role for the ESCRT-II complex subunit EAP30/SNF8 in IRF3-dependent innate antiviral defense

The activation of interferon (IFN)-regulatory factor-3 (IRF3), characterized by phosphorylation and nuclear translocation of the latent transcription factor, is central to initiating innate antiviral responses. Whereas much has been learned about the upstream pathways and signaling mechanisms leading to IRF3 activation, how activated IRF3 operates in the nucleus to control transcription of IFNs remains obscure. Here we identify EAP30 (a.k.a, SNF8/VPS22), an endosomal sorting complex required for transport (ESCRT)-II subunit, as an essential factor controlling IRF3-dependent antiviral defense. Depletion of EAP30, but not other ESCRT-II subunits, compromised IRF3-dependent induction of type I and III IFNs, IFN-stimulated genes (ISGs) and chemokines by double-stranded RNA or viruses. EAP30, however, was dispensable for the induction of inflammatory mediators of strict NF-κB target. Significantly, knockdown of EAP30 also impaired the establishment of an antiviral state against vesicular stomatitis virus and hepatitis C virus, which are of distinct viral families. Mechanistically, EAP30 was not required for IRF3 activation but rather acted at a downstream step. Specifically, a fraction of EAP30 localized within the nucleus, where it formed a complex with IRF3 and its transcriptional co-activator, CREB-binding protein (CBP), in a virus-inducible manner. These interactions promoted IRF3 binding to target gene promoters such as IFN-β, IFN-λ1 and ISG56. Together, our data describe an unappreciated role for EAP30 in IRF3-dependent innate antiviral response in the nucleus.

Bone Marrow-Derived Mesenchymal Stem Cells From Patients With Systemic Lupus Erythematosus Have a Senescence-Associated Secretory Phenotype Mediated by a Mitochondrial Antiviral Signaling Protein-Interferon-β Feedback Loop

OBJECTIVE

Bone marrow-derived mesenchymal stem cells (BM-MSCs) create a special microenvironment for hematopoiesis and immunity and display robust immunomodulatory properties that are impaired in systemic lupus erythematosus (SLE). This study was undertaken to identify the mechanisms of defects in human SLE BM-MSCs.

METHODS

Patients fulfilling SLE classification criteria and healthy controls (n = 6 per group) were recruited according to an institutional review board-approved protocol. BM-MSCs were isolated with low-density Ficoll-Hypaque, verified by flow cytometry, and studied using immunocytochemistry, real-time polymerase chain reaction, Western blotting, comet assay, β-galactosidase assay, and RNA interference.

RESULTS

SLE BM-MSCs had a senescent phenotype characterized by a reduced proliferation rate, increased production of reactive oxygen species, increased DNA damage and repair, increased expression of p53 and p16, which block the cell cycle, and altered cytokine production (increased proinflammatory cytokine production and decreased immunomodulatory cytokine production). Moreover, SLE BM-MSCs had a 5-fold increase in interferon-β (IFNβ) levels (P < 0.05 versus healthy controls) and increased IFNβ-induced messenger RNAs (mRNAs), including mRNA for the intracellular nucleic acid-sensing adaptor protein mitochondrial antiviral signaling protein (MAVS), whose expression was highly correlated with IFNβ levels (r > 0.9, P < 0.01). Since MAVS is known to induce IFNβ production, we hypothesized that there is a positive feedback loop between MAVS and IFNβ. Notably, silencing of MAVS markedly decreased IFNβ, p53, and p16 protein levels and expression of mRNAs for proinflammatory cytokines.

CONCLUSION

This study demonstrates a novel pathway for elevated IFNβ signaling in SLE that is not dependent on stimulation by immune complexes but rather is cell intrinsic and critically mediated by IFNβ and MAVS, implicating new pathways as potential therapeutic targets.

Nuclear domain 10 components upregulated via interferon during human cytomegalovirus infection potently regulate viral infection

Human cytomegalovirus (HCMV) is a ubiquitous betaherpesvirus that causes life-threatening disease in immunocompromised and immunonaïve individuals. Type I interferons (IFNs) are crucial molecules in the innate immune response to HCMV and are also known to upregulate several components of the interchromosomal multiprotein aggregates collectively referred to as nuclear domain 10 (ND10). In the context of herpesvirus infection, ND10 components are known to restrict gene expression. This raises the question as to whether key ND10 components (PML, Sp100 and hDaxx) act as anti-viral IFN-stimulated genes (ISGs) during HCMV infection. In this study, analysis of ND10 component transcription during HCMV infection demonstrated that PML and Sp100 were significantly upregulated whilst hDaxx expression remained unchanged. In cells engineered to block the production of, or response to, type I IFNs, upregulation of PML and Sp100 was not detected during HCMV infection. Furthermore, pre-treatment with an IFN-β neutralizing antibody inhibited upregulation of PML and Sp100 during both infection and treatment with HCMV-infected cell supernatant. The significance of ND10 components functioning as anti-viral ISGs during HCMV infection was determined through knockdown of PML, Sp100 and hDaxx. ND10 knockdown cells were significantly more permissive to HCMV infection, as previously described but, in contrast to control cells, could support HCMV plaque formation following IFN-β pre-treatment. This ability of HCMV to overcome the potently anti-viral effects of IFN-β in ND10 expression deficient cells provides evidence that ND10 component upregulation is a key mediator of the anti-viral activity of IFN-β.

DDX50 inhibits the replication of dengue virus 2 by upregulating IFN-β production

Dengue virus (DENV) infects approximately 390 million people per year, and each of the four DENV serotypes (DENV-1, DENV-2, DENV-3, and DENV-4) is capable of causing infection. At present, there is no antiviral drug available for the treatment of DENV. Several DExD/H-box helicases have been shown to be involved in the antiviral immune response or viral replication. In the present study, we investigated the role of DDX50 in DENV-2 RNA replication. Our data showed that the level of DENV-2 RNA increased in DDX50 knockdown cells during an early stage of viral infection and decreased in DDX50-overexpressing cells. DDX50, in conjunction with RIG-I and MDA5, upregulated the production of IFN-β in infected cells through an additive effect on the IFN-β promoter. Furthermore, transcription of several IFN-stimulated genes was increased in DDX50-overexpressing cells infected with DENV-2. These results provide evidence that DDX50 negatively regulates DENV-2 replication during the early stages of infection by inducing IFN-β production.

RIPK3 interacts with MAVS to regulate type I IFN-mediated immunity to Influenza A virus infection

The type I interferon pathway plays a critical role in both host defense and tolerance against viral infection and thus requires refined regulatory mechanisms. RIPK3-mediated necroptosis has been shown to be involved in anti-viral immunity. However, the exact role of RIPK3 in immunity to Influenza A Virus (IAV) is poorly understood. In line with others, we, herein, show that Ripk3-/- mice are highly susceptible to IAV infection, exhibiting elevated pulmonary viral load and heightened morbidity and mortality. Unexpectedly, this susceptibility was linked to an inability of RIKP3-deficient macrophages (Mφ) to produce type I IFN in the lungs of infected mice. In Mφ infected with IAV in vitro, we found that RIPK3 regulates type I IFN both transcriptionally, by interacting with MAVS and limiting RIPK1 interaction with MAVS, and post-transcriptionally, by activating protein kinase R (PKR)-a critical regulator of IFN-β mRNA stability. Collectively, our findings indicate a novel role for RIPK3 in regulating Mφ-mediated type I IFN anti-viral immunity, independent of its conventional role in necroptosis.

Clinical practice of analysis of anti-drug antibodies against interferon beta and natalizumab in multiple sclerosis patients in Europe: A descriptive study of test results

Antibodies against biopharmaceuticals (anti-drug antibodies, ADA) have been a well-integrated part of the clinical care of multiple sclerosis (MS) in several European countries. ADA data generated in Europe during the more than 10 years of ADA monitoring in MS patients treated with interferon beta (IFNβ) and natalizumab have been pooled and characterized through collaboration within a European consortium. The aim of this study was to report on the clinical practice of ADA testing in Europe, considering the number of ADA tests performed and type of ADA assays used, and to determine the frequency of ADA testing against the different drug preparations in different countries. A common database platform (tranSMART) for querying, analyzing and storing retrospective data of MS cohorts was set up to harmonize the data and compare results of ADA tests between different countries. Retrospective data from six countries (Sweden, Austria, Spain, Switzerland, Germany and Denmark) on 20,695 patients and on 42,555 samples were loaded into tranSMART including data points of age, gender, treatment, samples, and ADA results. The previously observed immunogenic difference among the four IFNβ preparations was confirmed in this large dataset. Decreased usage of the more immunogenic preparations IFNβ-1a subcutaneous (s.c.) and IFNβ-1b s.c. in favor of the least immunogenic preparation IFNβ-1a intramuscular (i.m.) was observed. The median time from treatment start to first ADA test correlated with time to first positive test. Shorter times were observed for IFNβ-1b-Extavia s.c. (0.99 and 0.94 years) and natalizumab (0.25 and 0.23 years), which were introduced on the market when ADA testing was already available, as compared to IFNβ-1a i.m. (1.41 and 2.27 years), IFNβ-1b-Betaferon s.c. (2.51 and 1.96 years) and IFNβ-1a s.c. (2.11 and 2.09 years) which were available years before routine testing began. A higher rate of anti-IFNβ ADA was observed in test samples taken from older patients. Testing for ADA varies between different European countries and is highly dependent on the policy within each country. For drugs where routine monitoring of ADA is not in place, there is a risk that some patients remain on treatment for several years despite ADA positivity. For drugs where a strategy of ADA testing is introduced with the release of the drug, there is a reduced risk of having ADA positive patients and thus of less efficient treatment. This indicates that potential savings in health cost might be achieved by routine analysis of ADA.

Interferon beta preparations for the treatment of multiple sclerosis patients differ in neutralizing antibody seroprevalence and immunogenicity

Development of neutralizing antibodies (NAbs) reduces the clinical efficacy of interferon beta (IFNβ) treatment in multiple sclerosis (MS) patients. The aim of this study was to evaluate NAb seroprevalence (frequency of patients with NAbs) and immunogenicity (titer levels) of IFNβ preparations in a clinical setting. We analysed 1115 consecutive MS patients, treated with one of the three available IFNβ preparations, for an average of 40 months (1 – 120 months), for the presence of NAbs with the MxA protein induction assay. Overall, 32% of patients were positive for NAbs with neutralizing titers above 10. The frequency of NAbs, ie, the seroprevalence, was 13% in Avonex-treated patients, 43% for Betaferon, 39% for Rebif22 and 30% for Rebif44. In addition, the potential to induce high titer levels, ie, the immunogenicity, was observed to differ between preparations. Avonex, showing the lowest seroprevalence, also showed low immunogenicity and typically induced low titers. Betaferon, showing the highest seroprevalence when inducing NAbs, induced lower titers compared to Rebif22 and Rebif44. Treatment duration over five years only marginally correlated with decreased seroprevalence and titer levels.

In conclusion, NAbs to IFNβ are common in a clinical setting and the IFNβ preparations differ not only in NAb seroprevalence, but also in immunogenicity. Multiple Sclerosis 2007; 13: 208–214. http://msj.sagepub.com

The Golgi-Associated Plant Pathogenesis-Related Protein GAPR-1 Enhances Type I Interferon Signaling Pathway in Response to Toll-Like Receptor 4

Lipopolysaccharide (LPS) activates Toll-like receptor 4 (TLR4) through the TIRAP-MyD88 dependent and TRAM-TRIF dependent signaling pathways, respectively. However, the underlying relevance between two signaling pathways remains largely elusive. Here, we investigated the role of the Golgi-Associated plant Pathogenesis-Related protein (GAPR-1) in type I interferon (IFN) signaling pathway in response to TLR4. We found that TIRAP-MyD88 dependent kinase IRAK1 phosphorylated GAPR-1 at Serine 58 site. The phosphorylation of GAPR-1 promoted its interaction with TRAM-TRIF dependent inhibitor TMED7, and impaired TMED7-mediated disruption of the TRAM-TRIF complex to trigger IFN-β and the IL10 secretion. Collectively, our study identified a previously unrecognized role for GAPR-1 to control a unifying TLR4 signaling complex and to regulate type I IFN signaling activation. Understanding the mechanism of GAPR-1 in type I IFN signaling pathway would provide strategies for treatment of infectious diseases.

[Herpes simplex encephalitis]

Herpes simplex encephalitis (HSE) is a rare disease, although it is the most common form of sporadic encephalitis worldwide. Recently, studies have provided important new insight into the genetic and immunological basis of HSE. However, even in the presence of antiviral treatment, mortality and morbidity remain relatively high. Therefore, precise and early diagnosis together with basic and clinical studies to gain better insight into the pathogenesis of HSE is a prerequisite for the development of improved prophylaxis and treatment of this severe disease.

Occurrence of Anti-Drug Antibodies against Interferon-Beta and Natalizumab in Multiple Sclerosis: A Collaborative Cohort Analysis

Immunogenicity of biopharmaceutical products in multiple sclerosis is a frequent side effect which has a multifactorial etiology. Here we study associations between anti-drug antibody (ADA) occurrence and demographic and clinical factors. Retrospective data from routine ADA test laboratories in Sweden, Denmark, Austria and Germany (Dusseldorf group) and from one research study in Germany (Munich group) were gathered to build a collaborative multi-cohort dataset within the framework of the ABIRISK project. A subset of 5638 interferon-beta (IFNβ)-treated and 3440 natalizumab-treated patients having data on at least the first two years of treatment were eligible for interval-censored time-to-event analysis. In multivariate Cox regression, IFNβ-1a subcutaneous and IFNβ-1b subcutaneous treated patients were at higher risk of ADA occurrence compared to IFNβ-1a intramuscular-treated patients (pooled HR = 6.4, 95% CI 4.9-8.4 and pooled HR = 8.7, 95% CI 6.6-11.4 respectively). Patients older than 50 years at start of IFNβ therapy developed ADA more frequently than adult patients younger than 30 (pooled HR = 1.8, 95% CI 1.4-2.3). Men developed ADA more frequently than women (pooled HR = 1.3, 95% CI 1.1-1.6). Interestingly we observed that in Sweden and Germany, patients who started IFNβ in April were at higher risk of developing ADA (HR = 1.6, 95% CI 1.1-2.4 and HR = 2.4, 95% CI 1.5-3.9 respectively). This result is not confirmed in the other cohorts and warrants further investigations. Concerning natalizumab, patients older than 45 years had a higher ADA rate (pooled HR = 1.4, 95% CI 1.0-1.8) and women developed ADA more frequently than men (pooled HR = 1.4, 95% CI 1.0-2.0). We confirmed previously reported differences in immunogenicity of the different types of IFNβ. Differences in ADA occurrence by sex and age are reported here for the first time. These findings should be further investigated taking into account other exposures and biomarkers.

The cross-reactivity of binding antibodies with different interferon beta formulations used as disease-modifying drugs in multiple sclerosis patients

Interferon beta (IFNb) preparations are commonly used as first-line therapy in relapsing-remitting multiple sclerosis (RRMS). They are, however, characterized by limited efficacy, partly due to the formation of anti-IFNb antibodies in patients.In this pilot study, we assessed with the ELISA method the presence of the binding antibodies (BAbs) against interferon beta after 2 years of therapy with subcutaneous interferon beta 1a (Rebif) in 49 RRMS patients. Antibody levels were established again within 1 year after treatment withdrawal. We used 3 interferons that are commercially available for MS therapy, namely Avonex (Biogen Idec Limited), Rebif (Merck Serono), and Betaferon (Bayer Pharma AG), as antigens.BAbs reacting with Rebif were found in 24.4% to 55% of patients, depending on the units of their expression. The levels of anti-Rebif antibodies remained high in 8 patients and in 4 patients they dropped significantly. Strong correlations were obtained in all assays (anti-Rebif-anti-Avonex, anti-Rebif-anti-Betaferon, and anti-Betaferon-anti-Avonex) and the existence of cross-reactivity in the formation of antibodies against all the tested formulations of interferon beta was confirmed. The levels of BAbs remain significant in the clinical context, and their assessment is the first choice screening; however, methods of BAbs evaluation can be crucial for further decisions. More studies are needed to confirm our results; specifically it would be of interest to evaluate methods of neutralizing antibodies identification, as we only assessed the binding antibodies. Nevertheless, our results support the concept that in interferon nonresponders, that are positive for binding antibodies, switching the therapy to alternative disease-modifying agent (for example glatiramer acetate, fingolimod, or natalizumab) is justified, whereas the switch to another interferon formulation will probably be of no benefit.

Respiratory Syncytial Virus-Infected Mesenchymal Stem Cells Regulate Immunity via Interferon Beta and Indoleamine-2,3-Dioxygenase

Respiratory syncytial virus (RSV) has been reported to infect human mesenchymal stem cells (MSCs) but the consequences are poorly understood. MSCs are present in nearly every organ including the nasal mucosa and the lung and play a role in regulating immune responses and mediating tissue repair. We sought to determine whether RSV infection of MSCs enhances their immune regulatory functions and contributes to RSV-associated lung disease. RSV was shown to replicate in human MSCs by fluorescence microscopy, plaque assay, and expression of RSV transcripts. RSV-infected MSCs showed differentially altered expression of cytokines and chemokines such as IL-1β, IL6, IL-8 and SDF-1 compared to epithelial cells. Notably, RSV-infected MSCs exhibited significantly increased expression of IFN-β (~100-fold) and indoleamine-2,3-dioxygenase (IDO) (~70-fold) than in mock-infected MSCs. IDO was identified in cytosolic protein of infected cells by Western blots and enzymatic activity was detected by tryptophan catabolism assay. Treatment of PBMCs with culture supernatants from RSV-infected MSCs reduced their proliferation in a dose dependent manner. This effect on PBMC activation was reversed by treatment of MSCs with the IDO inhibitors 1-methyltryptophan and vitamin K3 during RSV infection, a result we confirmed by CRISPR/Cas9-mediated knockout of IDO in MSCs. Neutralizing IFN-β prevented IDO expression and activity. Treatment of MSCs with an endosomal TLR inhibitor, as well as a specific inhibitor of the TLR3/dsRNA complex, prevented IFN-β and IDO expression. Together, these results suggest that RSV infection of MSCs alters their immune regulatory function by upregulating IFN-β and IDO, affecting immune cell proliferation, which may account for the lack of protective RSV immunity and for chronicity of RSV-associated lung diseases such as asthma and COPD.

[The methods of detection of binding and neutralizing antibodies to preparations of interferon-beta]

The human recombinant β-interferon is most frequently applied for treatment of remittent recurrent form of multiple sclerosis using pharmaceuticals. The clinical response to applied therapy is absent in some of patients that can be conditioned by development of antibodies too preparations. Depending on possibility of blocking binding of human recombinant β-interferon with its receptor, all antibodies are divided on binding and neutralizing ones. The purpose of study is to investigate analytical and clinical diagnostic parameters of tests using for detection of different types of antibodies synthesized against human recombinant β-interferon. The study sampling consisted of 33 patients with remittent recurrent form of multiple sclerosis receiving therapy with human recombinant β-interferon and also of 40 donors and 15 patients with multiple sclerosis without therapy with human recombinant β-interferon. The concentration of binding antibodies was measured by enzyme-linked immunosorbent assay. Also immune blotting assay was applied. The titer of neutralizing antibodies was determined using cell line HL-116 sensitive to human recombinant β-interferon. The binding and neutralizing antibodies were not detected in donors and patients without human recombinant β-interferon therapy. The prevalence of binding antibodies to human recombinant β-interferon amounted to 57.6% when analysis of samples using immune blotting assay was used and 60.6% when commercial testing system was applied. The statistical analysis of results demonstrated high convergence and correlation of values of concentrations of binding antibodies obtained using immune blotting assay and enzyme-linked immunosorbent assay (r=0.9159, p<0.0001). The clinically significant titers of neutralizing antibodies were detected in 21.21°% of patients. All patients with clinically significant titer of neutralizing antibodies were positive in relation to binding antibodies measured by immune blotting assay and enzyme-linked immunosorbent assay. The high correlation between values of titers of neutralizing antibodies and concentration of binding antibodies measured by immune blotting assay (r=0.7909, p=0.0055). The application in clinical practice of data concerning presence of binding and neutralizing antibodies to human recombinant β-interferon can input into optimization of therapy with expensive biologic preparations in patients with multiple sclerosis and other autoimmune diseases.

Identification of novel macrolides with antibacterial, anti-inflammatory and type I and III IFN-augmenting activity in airway epithelium

BACKGROUND

Exacerbations of asthma and COPD are triggered by rhinoviruses. Uncontrolled inflammatory pathways, pathogenic bacterial burden and impaired antiviral immunity are thought to be important factors in disease severity and duration. Macrolides including azithromycin are often used to treat the above diseases, but exhibit variable levels of efficacy. Inhaled corticosteroids are also readily used in treatment, but may lack specificity. Ideally, new treatment alternatives should suppress unwanted inflammation, but spare beneficial antiviral immunity.

METHODS

In the present study, we screened 225 novel macrolides and tested them for enhanced antiviral activity against rhinovirus, as well as anti-inflammatory activity and activity against Gram-positive and Gram-negative bacteria. Primary bronchial epithelial cells were grown from 10 asthmatic individuals and the effects of macrolides on rhinovirus replication were also examined. Another 30 structurally similar macrolides were also examined.

RESULTS

The oleandomycin derivative Mac5, compared with azithromycin, showed superior induction (up to 5-fold, EC50 = 5-11 μM) of rhinovirus-induced type I IFNβ, type III IFNλ1 and type III IFNλ2/3 mRNA and the IFN-stimulated genes viperin and MxA, yet had no effect on IL-6 and IL-8 mRNA. Mac5 also suppressed rhinovirus replication at 48 h, proving antiviral activity. Mac5 showed antibacterial activity against Gram-positive Streptococcus pneumoniae; however, it did not have any antibacterial properties compared with azithromycin when used against Gram-negative Escherichia coli (as a model organism) and also the respiratory pathogens Pseudomonas aeruginosa and non-typeable Haemophilus influenzae. Further non-toxic Mac5 derivatives were identified with various anti-inflammatory, antiviral and antibacterial activities.

CONCLUSIONS

The data support the idea that macrolides have antiviral properties through a mechanism that is yet to be ascertained. We also provide evidence that macrolides can be developed with anti-inflammatory, antibacterial and antiviral activity and show surprising versatility depending on the clinical need.

Measuring and evaluating interferon b-induced antibodies in patients with multiple sclerosis

Author for correspondence: Klaus Bendtzen, Institute for Inflammation Research IIR 7521, Rigshospitalet University Hospital, 9 Blegdamsvej, DK-2100 Copenhagen, Denmark. E-mail: address: kben@mail.dk Administration of interferons (IFNs) may induce antibodies that interfere with therapeutic efficacy. We have optimized and validated methods for large-scale economic screening. Sera from patients with relapsing-remitting multiple sclerosis (MS) were investigated for binding antibody (BAb) by protein-G affinity-chromatography radioimmunoassay and a commercially available enzyme immunoassay (EIA). Neutralizing antibody (NAb) was investigated by cytopathic effect assays (CEA) using both fixed amount and serially diluted sera. BAb correlated with log10-transformed titres obtained by EIA (r=0.70, p<0.0001); the latter, however, failed to demonstrate low-level BAb. Comparison of clinical significance of NAb-positivity measured by biological assays with different sensitivities demonstrated an optimal odds ratio for relapse rate using 10 laboratory units (LU)/mL. Purification of IgG prior to CEA removed toxicity from toxic sera. The neutralizing capacity data correlated linearly with log10-transformed titres obtained by a Kawade 10-to-1 LU/mL CEA (r=0.77, p<0.0001). In conclusion, neutralizing capacity CEA utilizing a fixed amount of serum predicts differences in relapse rates in IFNβ-treated MS patients and correlates with NAb titres of the 10-to- 1 LU/mL CEA. Neutralizing capacity CEA is less laborious and more economical than titre-based NAb assays and suitable for large-scale screenings of MS patients.

Longitudinal analyses of the effects of neutralizing antibodies on interferon beta-1b in relapsing-remitting multiple sclerosis

We have analysed data on exacerbation rates, Expanded Disability Status Scale (EDSS) scores, and lesion burdens using the results of two neutralizing antibody (NA B) assays (C PE and MxA) from the pivotal relapsing-remitting multiple sclerosis (MS) trial of interferon beta-1b (IFNB) with a longitudinal appro ach, where the influence of NA Bs in individual patients is assessed by comparing responses during NAB- positive and NA B-negative periods. There are apparent influences on exacerbation rate related to dose of IFNB, titer level, and duration of positivity. With the MxA assay, exacerbation rates after switching to NA B-positive status are estimated to be 28% higher [95% confidence interval (CI): (-15%, 92%)] and -2% higher [95% CI: (-21%, 21%)] on the low- and high-dose IFNB arms, respectively. When compared with all NA B-negative periods, exacerbation rates during NA B-positive periods are estimated to be 29% higher [95% C I: (0%, 67%)] and 18% higher [95% CI: (0%, 40%)] on the low- and high-dose IFNB arms, respectively. When NA B-positive patients again become NA B-negative, no evidence of increased exacerbation rates could then be demonstrated. More detailed exploratory analyses indicate that the effects are most evident in the approximately 20% of patients developing high titers. In these patients, the influence of NABs may be self-limited, as titers often diminish or NA Bs become undetectable with time.

Qualitative and quantitative analysis of antibody response against IFNβ in patients with multiple sclerosis

To date, inter-and intra-laboratory consistency of binding assays for measuring anti-interferon (IFN)β antibodies has not been assessed. In this investigation, two independent laboratories tested a library of 80 serum specimens obtained from multiple sclerosis (MS) patients treated with IFNβ. For binding antibodies (BAbs) evaluations, each laboratory used both a capture-ELISA (cELISA) and an enzyme-immuno-assay (EIA), which is commercially available. Samples were also tested for neutralizing antibodies (NAbs). Data demonstrated good intra-laboratory reliability (rpearson≥0.86), and a good overall agreement between the results obtained from the two centers, using both the cELISA (69/80 of observed agreements) and the EIA (67/80). Accordingly, kappa coefficients (K) showed good concurrence (K ≥ 0.651). There was also substantial agreement between cELISA and EIA measurements, as performed in both centers (Orbassano, 66/80, K = 0.631; Basel, 70/80, K = 0.717). However, by comparing NAbs and BAbs titers obtained with both assays, we found that a high degree of BAb-negative samples were positive in NAb-assay. Thus, our study does not support the usefulness of ELISA-based BAb assays as a screening tool for NAbs. Otherwise, BAb-assays can be used as a confirmation test, indicating that the decrease of the biological effects is due to antibodies. In this context, both ELISA-based assays are equally reliable techniques.

Persistence of neutralizing antibodies after discontinuation of IFNβ therapy in patients with relapsing-remitting multiple sclerosis

Objective The main objective was to follow serum levels of neutralizing antibodies (NABs) against interferon-beta (IFNβ) after discontinuation of IFNβ therapy.

Background A large proportion of patients treated with recombinant IFNβ for multiple sclerosis (MS) develop therapy-induced NABs. Knowledge of persistence of NABs after discontinuation of therapy is limited. Design/patients: A retrospective follow-up study of patients treated in Denmark for relapsing-remitting (RR) MS with IFNβ for at least 12 months. NAB-positive patients, who discontinued therapy, were followed up with measurements of NABs.

Methods We measured NAB-neutralizing capacity and NAB titres a.m. Kawade using a clinically validated cytopathic effect assay.

Results Thirty-seven patients were included. Mean follow-up time was 22 months. Of the 29 patients with a NAB titre at or above 25 prior to termination of therapy, only three patients reverted to a titre below 25. Of these, two had a titre below 200 and one patient a titre of 600 at the last examination before treatment stop. The longest post-treatment follow-up during which a patient maintained NAB positivity was 59 months.

Conclusion NABs against IFNβ, especially with high titres, tend to persist for a long time after discontinuation of IFNβ therapy. NABs should always be measured before reinstitution of IFNβ treatment in NAB-positive patients.

Differing immunogenic potentials of interferon beta preparations in multiple sclerosis patients

Interferon beta (IFNβ) is a first-line therapy for multiple sclerosis (MS). However, some patients experience a decline in efficacy with continued therapy due to the development of anti-IFNβ neutralizing antibodies (NAb). We investigated the frequency of NAb cross-sectionally in 846 MS patients who were receiving IFNβ-1b, IFNβ-1a im, or IFNβ-1a sc. The frequency of NAb in patients receiving IFNβ-1a im was lower (5%) than in patients treated with any other form of IFNβ (22-35%) (P < 0.0001). Binding antibodies (BAb) were measured in 808 patients. The frequency differed significantly between treatment groups, ranging from 45% (IFNβ-1a im) to 88% (IFNβ-1b). The proportion of NAb-positive patients within the BAb-positive group differed significantly among treatment groups, ranging between 12% (IFNβ-1a im) and 51% (IFNβ-1a sc). The median NAb titer from all IFNβ-1a-treated patients was higher than from IFNβ-1b-treated patients (446 versus 171 NU/mL, P = 0.04). Among NAb-positive patients, the frequency of NAb titers > 100 NU/mL was 71% for IFNβ-1a compared with 58% for IFNβ-1b (P = 0.04). Except for conflicting data regarding IFNβ-1a sc, the results are generally consistent with the literature and together with the differing proportion of NAb-positive patients within the BAb-positive group, provide further insight into the immunogeni-city of the IFNβ preparations.

Interferon-beta: the neutralizing antibody (NAb) titre predicts reversion to NAb negativity

Background: It has been reported that in some patients with MS who develop neutralizing antibodies (NAbs) against interferon beta (IFNb), antibody levels can initially increase and then decrease thereafter even when treatment is continued. Objective: To determine whether NAb titre correlates with time to reversion to NAb negativity in patients with multiple sclerosis (MS). Methods: Twenty-eight patients with MS who were NAb-positive during treatment with one of the currently available IFNbs were included in this retrospective study. NAb titres were determined by the myxovirus resistance protein A induction assay. Patients were considered NAb-positive if they had at least two consecutive samples with titres of]/20 neutralizing units (NU). Reversion to NAb-negative status was defined as two consecutive negative samples (NAb titre of B/20 NU) after NAb positivity. Results: When measured two years after treatment initiation, a NAb titre of B/75 NU had a 91.7% sensitivity and a 87.5% specificity for reversion to NAb negativity in the following two years (after a total of four years of treatment). In addition, somewhat surprisingly, patients whose serum converted to NAb-negative generally developed peak NAb titres earlier than patients who remained NAb-positive (mean time of first detection was 21 versus 38 months, respectively). Conclusion: The NAb titre might support treatment decisions in patients with MS whose test results are positive for NAbs.

The host STING pathway at the interface of cancer and immunity

A major subset of human cancers shows evidence for spontaneous adaptive immunity, which is reflected by the presence of infiltrating CD8+ T cells specific for tumor antigens within the tumor microenvironment. This observation has raised the question of which innate immune sensing pathway might detect the presence of cancer and lead to a natural adaptive antitumor immune response in the absence of exogenous infectious pathogens. Evidence for a critical functional role for type I IFNs led to interrogation of candidate innate immune sensing pathways that might be triggered by tumor presence and induce type I IFN production. Such analyses have revealed a major role for the stimulator of IFN genes pathway (STING pathway), which senses cytosolic tumor-derived DNA within the cytosol of tumor-infiltrating DCs. Activation of this pathway is correlated with IFN-β production and induction of antitumor T cells. Based on the biology of this natural immune response, pharmacologic agonists of the STING pathway are being developed to augment and optimize STING activation as a cancer therapy. Intratumoral administration of STING agonists results in remarkable therapeutic activity in mouse models, and STING agonists are being carried forward into phase I clinical testing.

Reduced sputum expression of interferon-stimulated genes in severe COPD

BACKGROUND

Exacerbations of COPD are frequent and commonly triggered by respiratory tract infections. The purpose of our study was to investigate innate immunity in stable COPD patients.

METHODS

Induced sputum was collected from 51 stable consecutive COPD patients recruited from the COPD Clinic of CHU Liege and 35 healthy subjects. Expression of interferons beta (IFN-β) and lambda1 (IL-29), IFN-stimulated genes (ISGs) MxA, OAS, and viperin were measured in total sputum cells by reverse transcription quantitative polymerase chain reaction (RT-qPCR). The presence of Picornaviruses was assessed by RT-PCR, while potential pathogenic microorganisms (PPM) were identified by sputum bacteriology.

RESULTS

Expression of IL-29 was found in 16 of 51 COPD patients (31%) and in nine of 35 healthy subjects (26%), while IFN-β was detected in six of 51 COPD patients (12%) and in two of 35 healthy subjects (6%). ISGs were easily detectable in both groups. In the whole group of COPD patients, OAS expression was decreased (P<0.05), while that of viperin was increased (P<0.01) compared to healthy subjects. No difference was found with respect to MxA. COPD patients from group D of Global Initiative for Chronic Obstructive Lung Disease (GOLD) had reduced expression of all three ISGs (P<0.01 for MxA, P<0.05 for OAS, and P<0.01 for viperin) as compared to those of group B patients. Picornaviruses were detected in eight of 51 (16%) COPD patients vs four of 33 (12%) healthy subjects, while PPM were detected in seven of 39 (18%) COPD patients and associated with raised sputum neutrophil counts. IFN-β expression was raised when either picornavirus or PPM were detected (P=0.06), but no difference was seen regarding IL-29 or ISGs.

CONCLUSION

ISGs expression was reduced in severe COPD that may favor exacerbation and contribute to disease progress by altering response to infection.

Prothymosin-α Variants Elicit Anti-HIV-1 Response via TLR4 Dependent and Independent Pathways

BACKGROUND

Prothymosin α (ProTα) (isoform 2: iso2) is a widely distributed, small acidic protein with intracellular and extracellular-associated functions. Recently, we identified two new ProTα variants with potent anti-HIV activity from CD8+ T cells and cervicovaginal lavage. The first is a splice variant of the ProTα gene known as isoB and the second is the product of ProTα pseudogene 7 (p7). Similarly to iso2, the anti-HIV activity of both variants is mediated by type I IFN. Here we tested whether the immunomodulatory activity of isoB and p7 are also TLR4 dependent and determined their kinetic of release in response to HIV-1 infection.

METHODS

Type I, type III, TNF-α and IL-6 mRNA inducing activity was determined in macrophages from wild type and TLR4 knockout mice treated with recombinant ProTα variants. Supernatants from mock and HIV infected cells were analyzed by mass spectrometry in positive and negative modes for the presence of ProTα variants. In silico structural and functional analysis of ProTα variants were performed.

RESULTS

We show that both isoB and p7 upregulate IFN-β, IFN-λ1, IL-6, TNF-α and RANTES mRNAs in primary human macrophages. The potent stimulation of IFN-β by the recombinant ProTα variants in human macrophages is dependent on the TLR4 pathway, whereas the induction of TNF-α and IL-6 may also occur independently of TLR4, suggesting the interaction of ProTα variants with other signaling molecules/receptors. In silico analyses confirmed that the novel isoB and p7 variants are intrinsically disordered proteins, which lack the NLS and mass spectrometry showed release of ProTα variants within minutes post HIV-1 infection. These features are consistent with the function of ProTα variants as damage associate molecular patterns (DAMPs).

CONCLUSIONS

Our findings indicate that ProTα variants strongly inhibit viral replication mainly, but not exclusively, through TLR4 signaling and that they are released within minutes of viral infection suggesting that they may function as DAMPs.

RNase L and the NLRP3-inflammasome: An old merchant in a new trade

The type I/III interferon (IFN)-inducible 2'-5'- oligoadenylate synthetase (OAS)/endoribonuclease L (RNase L) is a classical innate immune pathway that has been implicated in antiviral and antibacterial defense and also in hereditary prostate cancer. The OAS/RNase L pathway is activated when OAS senses double-stranded RNA and catalyzes the synthesis of 2'-5' linked oligodenylates (2-5A) from ATP. 2-5A then binds and activates RNase L, resulting cleavage of single-stranded RNAs. RNase L cleavage products are capable of activating RIG-like receptors such as RIG-I and MDA5 that leads to IFN-β expression during viral infection. Our recent findings suggest that beside the RLR pathway, RNase L cleavage products can also activate the NLRP3-inflammasome pathway, which requires DHX33 (DExD/H-box helicase) and the mitochondrial adaptor protein MAVS. Here we discuss this newly identified role of OAS-RNase L pathway in regulation of inflammasome signaling as an alternative antimicrobial mechanism that has potential as a target for development of new broad-spectrum antimicrobial and anti-inflammatory therapies.