IFN-β Treatment Research Articles

Poor responses to interferon-beta treatment in patients with neuromyelitis optica and multiple sclerosis with long spinal cord lesions.

Interferon-beta (IFN-β) treatment may not be effective in neuromyelitis optica (NMO). Whether the poor response to IFN-β is related to long spinal cord lesions (LSCL) or the NMO disease entity itself is unclear. We evaluated the spinal cord involvement of patients with multiple sclerosis (MS) and NMO, as well as the response after receiving IFN-β. Forty-nine MS and 21 NMO patients treated with IFN-β for at least 2 years from 2002–2008 were enrolled in this study and the treatment response was analyzed 2 years post-treatment. In the study, spinal cord lesions were present in 57.1% (28/49) of the MS patients, of which 16.3% (8/49) presented spinal cord lesions longer than 3 vertebral segments (LSCL). Responses to IFN-β treatment were seen in 69.3% (34/49) of all the MS cases, of which the appropriate response rates were 76.1% (16/21) in MS patients without spinal cord lesions and 37.5% (3/8) in patients with LSCL. Only 14.2% (3/21) of NMO patients responded to IFN-β treatment. In conclusion, spinal cord lesion is common in MS patients in Taiwan. Both NMO and MS patients with LSCL had a poor response to IFN-β treatment. NMO patients had a worse response to IFN-β treatment than MS patients with LSCL, which shows that the crucial structural defect is something other than LSCL such as the elevated serum IL17 level in NMO compared to MS.

BAb and MxA as Functional Biomarkers in Routine Clinical Laboratories for the Determination of Anti-IFN-Beta Antibodies and Their Bioactivity Levels in Multiple Sclerosis Patients

In MS patients under IFNβ treatment to seek alternative treatments timely is important that anti-IFNβ antibodies and/or in vivo biologic activity loss detection in these. The most common diagnostic markers used for this purpose are BAb, Nab, and MxA. In this article, we aimed to establish the availability and feasibility of the correlation between BAb and MxA gene expression (mRNA) levels using evaluation of responses to IFNβ treatment for MS patients with a routine laboratory follow-up strategy in a major Turkish MS center. Bab seropositivity was determined in blood samples of 218 MS patients treated with different IFNβ preparations and MxA mRNA levels were measured in 128 patients among the total population. BAb seropositivity ratios to im INF-β 1a, scINF-β 1a, and sc INF-β 1b were 21.4%, 28.6%, and 70.4%, respectively (total 40%), and total loss of bioactivity (MxA mRNA) were 9.3%, 9.5%, and 11.6%, respectively (total 10.2%). The correlation between high BAb titers and low MxA mRNA levels was highly significant (P = 0.00003). Our data indicate that there is a good correlation between especially high BAbs levels and diminished MxA mRNA levels.

Small non-coding RNA signature in multiple sclerosis patients after treatment with interferon-β.

BackgroundNon-coding small RNA molecules play pivotal roles in cellular and developmental processes by regulating gene expression at the post-transcriptional level. In human diseases, the roles of the non-coding small RNAs in specific degradation or translational suppression of the targeted mRNAs suggest a potential therapeutic approach of post-transcriptional gene silencing that targets the underlying disease etiology. The involvement of non-coding small RNAs in the pathogenesis of neurodegenerative diseases such as Alzheimer’s , Parkinson’s disease and Multiple Sclerosis has been demonstrated. Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, characterized by chronic inflammation, demyelination and scarring as well as a broad spectrum of signs and symptoms. The current standard treatment for SM is interferon ß (IFNß) that is less than ideal due to side effects. In this study we administered the standard IFN-ß treatment to Relapsing-Remitting MS patients, all responder to the therapy; then examined their sncRNA expression profiles in order to identify the ncRNAs that were associated with MS patients’ response to IFNß.Methods40 IFNß treated Relapsing-Remitting MS patients were enrolled. We analyzed the composition of the entire small transcriptome by a small RNA cloning method, using peripheral blood from Relapsing-Remitting MS patients at baseline and 3 and 6 months after the start of IFNß therapy. Real-time qPCR from the same patients group and from 20 additional patients was performed to profile miRNAs expression.ResultsBeside the altered expression of several miRNAs, our analyses revealed the differential expression of small nucleolar RNAs and misc-RNAs.For the first time, we found that the expression level of miR-26a-5p changed related to INF-β response. MiR-26a-5p expression was significantly higher in IFN-β treated RRMS patients at 3 months treatment, keeping quite stable at 6 months treatments.ConclusionsOur results might provide insights into the mechanisms of action of IFN-β treatment in MS and provide fundamentals for the development of new biomarkers and/or therapeutic tools.

Interferon beta treatment of multiple sclerosis increases serum interleukin-7

Background: Interleukin-7 (IL-7) is a non-redundant cytokine for T-cell development and survival. The IL-7 signaling pathway has been genetically and functionally associated with several autoimmune diseases including multiple sclerosis (MS). Objective: The objective of this paper is to elucidate the effect of the widely used immunomodulatory MS therapy interferon beta (IFNβ) on IL-7 homeostasis. Methods: Swedish MS patients were screened for IL-7 concentration in serum and blood cell counts. IL-7 receptor alpha chain (IL-7Rα) expression was determined by semi-quantitative real-time polymerase chain reaction (PCR) and flow cytometry. Results: IFNβ treatment led to significantly increased serum IL-7 levels (mean: 17 pg/ml) compared with healthy controls (mean: 7.6 pg/ml) and natalizumab-treated patients (mean: 5.3 pg/ml). In vitro and in vivo, peripheral blood leukocytes showed decreased IL-7Rα expression and IL-7 consumption upon IFNβ exposure, suggesting that their IL-7 responsiveness is impaired during treatment. Conclusions: MS patients undergoing IFNβ treatment have increased serum IL-7 levels and decreased IL-7 consumption. Given IL-7’s important role in T-cell immunity, this relationship may be highly relevant for IFNβ’s treatment efficacy.

Innate immune responses play a role in heterogeneity of EAE. (INM8P.445)

Abstract Multiple sclerosis (MS) is a heterogeneous disease, which makes treatment difficult. For example, responsiveness to IFNβ treatment among MS patients varies to a great extent. Using EAE as an animal model of MS, we found that IFNβ treatment is not effective when EAE develops in the absence of the NLRP3 inflammasome with alternative EAE induction methods. Importantly, innate immune responses triggered by alternative EAE induction methods played a role to generate different subtype of EAE. This led us to hypothesize EAE have subtypes (although they are not mutually exclusive), at least based on the dependency of the disease pathology on the NLRP3 inflammasome and on the response to IFNβ. In NLRP3 inflammasome-dependent IFNβ-responsive EAE (termed type-A EAE), the NLRP3 inflammasome plays a key role as a pathogenic factor of EAE by enhancing immune cell migration and the resulting immune cell recruitment in the CNS. On the other hand, the NLRP3 inflammasome is not essential for EAE induction, and IFNβ treatment is not effective in NLRP3 inflammasome-independent EAE (termed Type-B EAE). Type-A and Type-B EAE show clear difference in their phenotypes and pathological mechanisms, mediated by differential activation of innate immune responses. M.I. performed all the experiments and M.L.S. is the corresponding author of this study.

Efficacy of IFN-λ1 to protect human airway epithelial cells against human rhinovirus 1B infection.

Impaired interferon (IFN) production has been observed in various obstructive respiratory diseases. This contributes to enhanced sensitivity towards viral infections triggering acute exacerbations. To compensate for this impaired host IFN response, there is need to explore new therapeutic strategies, like exogenous administration of IFNs as prophylactic treatment. In the present study, we examined the protective potential of IFN-λ1 and compared it with the previously established protecting effect of IFN-β. A549 cells and human primary bronchial epithelial cells were first treated with either IFN-β (500 IU/ml) or IFN-λ1 (500 ng/ml) for 18 h. For infection, two approaches were adopted: i) Continuous scenario: after pre-treatment, cells were infected immediately for 24 h with human rhinovirus 1B (HRV1B) in IFN-containing medium, or were cultured for another 72 h in IFN-containing medium, and then infected for 24 h with HRV1B, ii) Pre-treatment scenario: IFN-containing medium was replaced after 18 h and cells were infected for 4 h either immediately after pre-treatment or after additional culturing for 72 h in IFN-free medium. The protective effect was evaluated in terms of reduction in the number of viral copies/infectious progeny, and enhanced expression of IFN-stimulated genes (ISGs). In both cell types and in both approaches, IFN-λ1 and IFN-β treatment resulted in pronounced and long-lasting antiviral effects exemplified by significantly reduced viral copy numbers and diminished infectious progeny. This was associated with strong up-regulation of multiple ISGs. However, in contrast to the IFN-β induced expression of ISGs, which decreased over time, expression of ISGs induced by IFN-λ1 was sustained or even increased over time. Here we demonstrate that the protective potential of IFN-λ1 is comparable to IFN-β. Yet, the long-lasting induction of ISGs by IFN-λ1 and most likely less incitement of side effects due to more localized expression of its receptors could make it an even more promising candidate for prophylactic treatment than IFN-β.

A comparative study of experimental mouse models of central nervous system demyelination

Several mouse models of multiple sclerosis (MS) are now available. We have established a mouse model, in which ocular infection with a recombinant HSV-1 that expresses murine IL-2 constitutively (HSV-IL-2) causes CNS demyelination in different strains of mice. This model differs from most other models in that it represents a mixture of viral and immune triggers. In the present study, we directly compared MOG35–55, MBP35–47, and PLP190–209 models of EAE with our HSV-IL-2-induced MS model. Mice with HSV-IL-2-induced and MOG-induced demyelinating diseases demonstrated a similar pattern and distribution of demyelination in their brain, spinal cord, and optic nerves. In contrast, no demyelination was detected in the optic nerves of MBP- and PLP-injected mice. IFN-β injections significantly reduced demyelination in brains of all groups, in the spinal cords of the MOG and MBP groups, and completely blocked it in the spinal cords of the PLP and HSV-IL-2 groups as well as in optic nerves of MOG and HSV-IL-2 groups. In contrast to IFN-β treatment, IL-12p70 protected the HSV-IL-2 group from demyelination, while IL-4 was not effective at all in preventing demyelination. MOG-injected mice showed clinical signs of paralysis and disease-related mortality whereas mice in the other treatment groups did not. Collectively, the results indicate that the HSV-IL-2 model and the MOG model complement each other and, together, provide unique insights into the heterogeneity of human MS.

Interferon-β Induces Loss of Spherogenicity and Overcomes Therapy Resistance of Glioblastoma Stem Cells

Glioblastoma is the most common malignant brain tumor in adults and characterized by a poor prognosis. Glioma cells expressing O(6)-methylguanine DNA methyltransferase (MGMT) exhibit a higher level of resistance toward alkylating agents, including the standard of care chemotherapeutic agent temozolomide. Here, we demonstrate that long-term glioma cell lines (LTL) as well as glioma-initiating cell lines (GIC) express receptors for the immune modulatory cytokine IFN-β and respond to IFN-β with induction of STAT-3 phosphorylation. Exposure to IFN-β induces a minor loss of viability, but strongly interferes with sphere formation in GIC cultures. Furthermore, IFN-β sensitizes LTL and GIC to temozolomide and irradiation. RNA interference confirmed that both IFN-β receptors, R1 and R2, are required for IFN-β-mediated sensitization, but that sensitization is independent of MGMT or TP53. Most GIC lines are highly temozolomide-resistant, mediated by MGMT expression, but nevertheless susceptible to IFN-β sensitization. Gene expression profiling following IFN-β treatment revealed strong upregulation of IFN-β-associated genes, including a proapoptotic gene cluster, but did not alter stemness-associated expression signatures. Caspase activity and inhibition studies revealed the proapoptotic genes to mediate glioma cell sensitization to exogenous death ligands by IFN-β, but not to temozolomide or irradiation, indicating distinct pathways of death sensitization mediated by IFN-β. Thus, IFN-β is a potential adjunct to glioblastoma treatment that may target the GIC population. IFN-β operates independently of MGMT-mediated resistance, classical apoptosis-regulatory networks, and stemness-associated gene clusters.

Comparative pharmacogenetics of multiple sclerosis: IFN-β versus glatiramer acetate.

Various diseases require the selection of preferable treatment out of available alternatives. Multiple sclerosis (MS), an autoimmune inflammatory/neurodegenerative disease of the CNS, requires long-term medication with either specific disease-modifying therapy (DMT) - IFN-β or glatiramer acetate (GA) - which remain the only first-line DMTs in all countries. A significant share of MS patients are resistant to treatment with one or the other DMT; therefore, the earliest choice of preferable DMT is of particular importance. A number of conventional pharmacogenetic studies performed up to the present day have identified the treatment-sensitive genetic biomarkers that might be specific for the particular drug; however, the suitable biomarkers for selection of one or another first-line DMT are remained to be found. Comparative pharmacogenetic analysis may allow the identification of the discriminative genetic biomarkers, which may be more informative for an a priori DMT choice than those found in conventional pharmacogenetic studies. The search for discriminative markers of preferable first-line DMT, which differ in carriage between IFN-β responders and GA responders as well as between IFN-β nonresponders and GA nonresponders, has been performed in 253 IFN-β-treated MS patients and 285 GA-treated MS patients. A bioinformatics algorithm for identification of composite biomarkers (allelic sets) was applied on a unified set of immune-response genes, which are relevant for IFN-β and/or GA modes of action, and identical clinical criteria of treatment response. We found the range of discriminative markers, which include polymorphic variants of CCR5, IFNAR1, TGFB1, DRB1 or CTLA4 genes, in different combinations. Every allelic set includes the CCR5 genetic variant, which probably suggests its crucial role in the modulation of the DMT response. Special attention should be given to the (CCR5*d+ IFNAR1*G) discriminative combination, which clearly points towards IFN-β treatment choice for carriers of this combination. As a whole the comparative approach provides an option for the identification of prognostic composite biomarkers for a preferable medication among available alternatives.

Assessment of cancer risk with β-interferon treatment for multiple sclerosis

The risk of cancer after exposure to the β-interferons (IFNβs) for multiple sclerosis (MS) has not been established. We assessed whether IFNβ treatment for MS is associated with cancer risk or the risk of specific cancers in a population-based observational study. The British Columbia MS database was linked to the provincial Cancer Registry, Vital Statistics death files and Health Registration files. Using a nested case-control design, MS cancer cases were matched with up to 20 randomly selected MS controls at the date of cancer diagnosis by sex, age (± 5 years) and study entry year using incidence density sampling. Associations between treatment exposure and overall or specific (breast, colorectal, lung and prostate) cancers were estimated by conditional logistic regression, adjusted for MS disease duration and age. Tumour size at cancer diagnosis was compared between treated and untreated patients using the stratified Wilcoxon test to explore potential lead time bias. The cohort included 5146 relapsing-onset MS patients and 48,705 person-years of follow-up, during which 227 cancers were diagnosed. Exposure to IFNβ was not significantly different for cases and controls (OR 1.28; 95% CI 0.87 to 1.88). There was a non-significant trend towards an increased risk of IFNβ exposure in the breast cancer cases (OR 1.77; 95% CI 0.92 to 3.42), but no evidence of a dose-response effect. Tumour size was similar between IFNβ treated and untreated cases. There was no evidence of an increased cancer risk with exposure to IFNβ over a 12-year observation period. However, the trend towards an association between IFNβ and breast cancer should be investigated further.

Tumor-Targeted IFN-β Treatment Overcomes Antibody Resistance

Abstract Tumor-specific antibodies fused with IFN-β effectively treat antibody-resistant tumors.

Death-associated protein kinase 1 is an IRF3/7-interacting protein that is involved in the cellular antiviral immune response

Interferon regulatory factor (IRF) 7 has been demonstrated to be a master regulator of virus-induced type I interferon production (IFN), and it plays a central role in the innate immune response against viruses. Here, we identified death-associated protein kinase 1 (DAPK1) as an IRF7-interacting protein by tandem affinity purification (TAP). Viral infection induced DAPK1-IRF7 and DAPK1-IRF3 interactions and overexpression of DAPK1 enhanced virus-induced activation of the interferon-stimulated response element (ISRE) and IFN-β promoters and the expression of the IFNB1 gene. Knockdown of DAPK1 attenuated the induction of IFNB1 and RIG-I expression triggered by viral infection or IFN-β, and they were enhanced by viral replication. In addition, viral infection or IFN-β treatment induced the expression of DAPK1. IFN-β treatment also activated DAPK1 by decreasing its phosphorylation level at serine 308. Interestingly, the involvement of DAPK1 in virus-induced signaling was independent of its kinase activity. Therefore, our study identified DAPK1 as an important regulator of the cellular antiviral response.

Interferon β-1a reduces increased interleukin-16 levels in multiple sclerosis patients

There is convergent evidence for an important role of interleukin-16 (IL-16) in the pathogenesis of multiple sclerosis (MS). IL-16 serves as a chemoattractant for different immune cells that are involved in developing lesions. Here, we compared IL-16 levels of MS patients and controls and addressed the long-term effect of IFN-β, the most common immunomodulatory MS therapy, on IL-16 serum levels in MS patients over 2 years. Beyond this, we analysed the expression of IL-16 in two CD4(+) T-cell subsets, Th1 and Th17 cells, which are important autoimmune mediators and affected by IFN-β treatment, derived from myelin-specific T-cell transgenic mice. IL-16 serum levels of 17 controls and of 16 MS patients before therapy and at months 1, 2, 3, 6, 9, 12 and 24 during IFN-β1a therapy were determined by ELISA. MRI was performed before therapy, at months 12 and 24. IL-16 expression of in vitro differentiated murine myelin oligodendrocyte glycoprotein (MOG)-specific Th1 and Th17 cells was quantified by real-time PCR. Before therapy, MS patients showed significantly elevated IL-16 levels compared with controls irrespective of disease activity determined by MRI. Therapy with IFN-β1a led to a significant linear decrease in IL-16 serum levels beginning after 2 months. MOG-specific Th17 cells expressed more IL-16 than Th1 cells. Reduction in increased IL-16 levels may be of relevance for the therapeutic effect of IFN-β1a in MS. Easily accessible IL-16 serum levels hold a potential as biomarker of treatment efficacy in MS.

Antibodies against interferon-beta in neuromyelitis optica patients

Neuromyelitis optica (NMO) is an antibody-mediated autoimmune inflammatory disease of the CNS. A poor response to treatment with recombinant interferon beta (IFN-ß) in NMO patients has been suggested, although the precise mechanisms remain uncertain. We analyzed occurrence and clinical consequences of IFN-neutralizing antibodies (NAbs) in 15 IFN-ß treated NMO-patients from a population-based retrospective case series cohort. NMO patients not treated with IFN-ß acted as a reference group. IFN-ß antibody determinations included binding antibodies (BAbs) measured by immunoassay and NAbs measured by a neutralization bioassay. Antibodies were determined 6–36months after initiation of IFN-β therapy and NAbs additionally 5–10years post-therapy. BAbs were detected in 14/15 NMO patients; 6/15 were NAbs-positive (3 at 5–10years post-therapy) two of those anti-AQP4 antibody-positive; seven of the nine NAbs-negative patients were anti-AQP4 antibody-positive. Eleven patients (three NAbs-positive, eight NAbs-negative) developed cerebral lesions and 12 patients (four NAbs-positive, eight NAbs-negative) spinal cord lesions on magnetic resonance imaging as gadolinium positive lesions or T2-weighted lesions, at significantly higher frequencies than NMO reference group (p<0.009). Exacerbation occurred within 90days in four and 6–36months in eight patients. Progression of disease activity in NMO patients occurred during IFN-β treatment, irrespective of IFN-neutralizing antibody status.

Cytokines as Biomarkers of Treatment Response to IFN β in Relapsing-Remitting Multiple Sclerosis.

Background. MS patients show a remarkable heterogeneity in their response to disease modifying treatments. Given the need for early treatment initiation and the diversity of available options, a predictive marker that indicates good or poor response to treatment is highly desirable. Objective. To find a biomarker for treatment response to IFNβ among pro- and anti-inflammatory cytokines. Materials and Methods. IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10, IL-17A, and TGF-β1 levels were measured in serum and CSF of 43 patients with RR-MS who were followed up for a mean period of 5.3 years. Thirty-five patients received IFNβ treatment and were divided into good responders (GR, n = 19) and poor responders (PR, n = 16). The remaining 8 patients showed a very favorable outcome and remained untreated (noRx). Results. GR had significantly higher serum baseline levels of IL-17A than PR and significantly higher serum levels of IL-17A, IFN-γ, TNF-α, and IL-2 than noRx. PR had significantly higher IFN-γ serum levels than noRx. No significant differences were observed in serum levels of IL-6, IL-4, IL-10, and TGF-β1 or the levels of all cytokines measured in CSF between the 3 groups of patients. Conclusions. Baseline serum levels of IL-17A can be used as a biomarker of IFNβ treatment response.

Sema4A as a biomarker predicting responsiveness to IFN β treatment

Approximately one-third of patients with multiple sclerosis (MS) exhibit markedly high-level-expression of Sema4A. The expression of Sema4A is increased on DCs in MS patients and shed from these cells in a metalloproteinase-dependent manner. DC-derived Sema4A is critical for Th17 cell differentiation, and MS patients with high Sema4A levels exhibit Th17 skewing. Furthermore, patients with high Sema4A levels have more severe disabilities and are unresponsive to IFN-β treatment. We investigated whether recombinant Sema4A abrogates the efficacy of IFN-β in mice with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Administration of Sema4A concurrently with IFN-β abrogated the efficacy of IFN-β. These effects of Sema4A were attributed to promote Th1 and Th17 differentiation and to increase adhesive activation of T cells to endothelial cells, even in the presence of IFN-β.Thus unresponsiveness to IFN-β treatment of MS patients with high Sema4A was also confirmed by model mice EAE. We recommend assaying Sema4A first, and then selecting DMD other than IFN-β for patients with high Sema4A.

Guidelines on the clinical use for the detection of neutralizing antibodies (NAbs) to IFN beta in multiple sclerosis therapy: report from the Italian Multiple Sclerosis Study group

Interferon beta (IFNβ) was the first specific disease-modifying treatment licensed for relapsing-remitting multiple sclerosis, and is still one of the most commonly prescribed treatments. A strong body of evidence supports the effectiveness of IFNβ preparations in reducing the annual relapse rate, magnetic resonance (MRI) disease activity and disease progression. However, the development of binding/neutralizing antibodies (BAbs/NAbs) during treatment negatively affects clinical and MRI outcomes. Therefore, guidelines for the clinical use for the detection of NAbs in MS may result in better treatment of these patients. In October 2012, a panel of Italian neurologists from 17 MS clinics convened in Milan to review and discuss data on NAbs and their clinical relevance in the treatment of MS. In this paper, we report the panel's recommendations for the use of IFNβ Nabs detection in the early identification of IFNβ non-responsiveness and the management of patients on IFNβ treatment in Italy, according to a model of therapeutically appropriate care.

Assessing treatment response to interferon-β: is there a role for MRI?

Interferon-β (IFN-β) has been shown to reduce relapse rates in multiple sclerosis; however, the clinical response appears to vary among individuals. Can early MRI be used to identify those patients who have a poor response to treatment? A systematic review of studies examining differential treatment response and clinical endpoints in groups defined as responders or nonresponders to IFN-β was performed. Meta-analytic techniques were used to combine study results where appropriate. Patients with MRI evidence of poor response to IFN-β treatment as defined by either ≥2 new hyperintense T2 lesions or new gadolinium-enhancing lesions had significantly increased risk of both future relapses and progression as defined by the Expanded Disability Status Scale. There appeared to be an increased risk of poor outcomes 16 years after treatment initiation in those with an initial poor response to treatment. Previous evidence has shown this not to be the case in placebo arms of clinical trials. For those patients starting IFN-β, early MRI, within 6 to 24 months after starting treatment, has the potential to provide important information when counseling patients about the likelihood of future treatment failure. This can inform treatment decisions before clinical relapses or disease progression.

Type I interferons up-regulate the expression and signalling of p75 NTR/TrkA receptor complex in differentiated human SH-SY5Y neuroblastoma cells

Both type I interferons (IFNs) and neurotrophins regulate neuroadaptive responses, but relatively little is known on the interaction between these two classes of regulatory proteins. Here we investigated the effect of IFN-β on the expression and functional activity of the common neurotrophin receptor p75NTR and the nerve growth factor (NGF) receptor TrkA. In differentiated human SH-SY5Y neuroblastoma cells prolonged exposure to IFN-β up-regulated p75NTR and TrkA levels, failed to affect the content of sortilin, a p75NTR co-receptor, and, consistent with our previous finding, down-regulated the brain-derived neurotrophic factor receptor TrkB. Quantitative real time RT-PCR indicated that IFN-β increased p75NTR and TrkA mRNA levels. In control and IFN-β treated cells proNGF failed to induce c-Jun N-terminal kinase and nuclear factor/kB activation, two p75NTR/sortilin signalling pathways mediating neuronal death. On the other hand, IFN-β treatment enhanced TrkA autophosphorylation and signalling induced by NGF and proNGF. Knockdown of p75NTR by siRNA reduced TrkA activation by proNGF and a subnanomolar concentration of NGF, whereas co-immunoprecipitation indicated close association of p75NTR and TrkA. Co-treatment with either NGF or proNGF reduced IFN-β pro-apoptotic and anti-neurotrophic effects. Similarly, in primary mouse hippocampal neurons IFN-β increased p75NTR and TrkA expression, down-regulated TrkB and enhanced NGF-induced phosphorylation of the pro-survival protein kinase Akt. The data demonstrate that in neuronal cells IFN-β differentially affects the expression and signalling of neurotrophin receptors and suggest that the up-regulation of the p75NTR/TrkA signalling complex may constitute a novel mechanism by which this cytokine selectively attenuates its pro-apoptotic effect in NGF-responsive cells.

Type I Interferon Protects against Pneumococcal Invasive Disease by Inhibiting Bacterial Transmigration across the Lung

Streptococcus pneumoniae infection is a leading cause of bacterial pneumonia, sepsis and meningitis and is associated with high morbidity and mortality. Type I interferon (IFN-I), whose contribution to antiviral and intracellular bacterial immunity is well established, is also elicited during pneumococcal infection, yet its functional significance is not well defined. Here, we show that IFN-I plays an important role in the host defense against pneumococci by counteracting the transmigration of bacteria from the lung to the blood. Mice that lack the type I interferon receptor (Ifnar1 −/−) or mice that were treated with a neutralizing antibody against the type I interferon receptor, exhibited enhanced development of bacteremia following intranasal pneumococcal infection, while maintaining comparable bacterial numbers in the lung. In turn, treatment of mice with IFNβ or IFN-I-inducing synthetic double stranded RNA (poly(I:C)), dramatically reduced the development of bacteremia following intranasal infection with S. pneumoniae. IFNβ treatment led to upregulation of tight junction proteins and downregulation of the pneumococcal uptake receptor, platelet activating factor receptor (PAF receptor). In accordance with these findings, IFN-I reduced pneumococcal cell invasion and transmigration across epithelial and endothelial layers, and Ifnar1 −/− mice showed overall enhanced lung permeability. As such, our data identify IFN-I as an important component of the host immune defense that regulates two possible mechanisms involved in pneumococcal invasion, i.e. PAF receptor-mediated transcytosis and tight junction-dependent pericellular migration, ultimately limiting progression from a site-restricted lung infection to invasive, lethal disease.