Fifty years of interferon research: aiming at a moving target

Hemagglutinin of Influenza A Virus Antagonizes Type I Interferon (IFN) Responses by Inducing Degradation of Type I IFN Receptor 1

Influenza A virus (IAV) employs diverse strategies to circumvent type I interferon (IFN) responses, particularly by inhibiting the synthesis of type I IFNs. However, it is poorly understood if and how IAV regulates the type I IFN receptor (IFNAR)-mediated signaling mode. In this study, we demonstrate that IAV induces the degradation of IFNAR subunit 1 (IFNAR1) to attenuate the type I IFN-induced antiviral signaling pathway. Following infection, the level of IFNAR1 protein, but not mRNA, decreased. Indeed, IFNAR1 was phosphorylated and ubiquitinated by IAV infection, which resulted in IFNAR1 elimination. The transiently overexpressed IFNAR1 displayed antiviral activity by inhibiting virus replication. Importantly, the hemagglutinin (HA) protein of IAV was proved to trigger the ubiquitination of IFNAR1, diminishing the levels of IFNAR1. Further, influenza A viral HA1 subunit, but not HA2 subunit, downregulated IFNAR1. However, viral HA-mediated degradation of IFNAR1 was not caused by the endoplasmic reticulum (ER) stress response. IAV HA robustly reduced cellular sensitivity to type I IFNs, suppressing the activation of STAT1/STAT2 and induction of IFN-stimulated antiviral proteins. Taken together, our findings suggest that IAV HA causes IFNAR1 degradation, which in turn helps the virus escape the powerful innate immune system. Thus, the research elucidated an influenza viral mechanism for eluding the IFNAR signaling pathway, which could provide new insights into the interplay between influenza virus and host innate immunity.

IMPORTANCE

Influenza A virus (IAV) infection causes significant morbidity and mortality worldwide and remains a major health concern. When triggered by influenza viral infection, host cells produce type I interferon (IFN) to block viral replication. Although IAV was shown to have diverse strategies to evade this powerful, IFN-mediated antiviral response, it is not well-defined if IAV manipulates the IFN receptor-mediated signaling pathway. Here, we uncovered that influenza viral hemagglutinin (HA) protein causes the degradation of type I IFN receptor subunit 1 (IFNAR1). HA promoted phosphorylation and polyubiquitination of IFNAR1, which facilitated the degradation of this receptor. The HA-mediated elimination of IFNAR1 notably decreased the cells' sensitivities to type I IFNs, as demonstrated by the diminished expression of IFN-induced antiviral genes. This discovery could help us understand how IAV regulates the host innate immune response to create an environment optimized for viral survival in host cells.

Therapeutic applications of TRAIL receptor agonists in cancer and beyond

TRAIL/Apo-2L is a member of the TNF superfamily first described as an apoptosis-inducing cytokine in 1995. Similar to TNF and Fas ligand, TRAIL induces apoptosis in caspase-dependent manner following TRAIL death receptor trimerization. Because tumor cells were shown to be particularly sensitive to this cytokine while normal cells/tissues proved to be resistant along with being able to synthesize and release TRAIL, it was rapidly appreciated that TRAIL likely served as one of our major physiologic weapons against cancer. In line with this, a number of research laboratories and pharmaceutical companies have attempted to exploit the ability of TRAIL to kill cancer cells by developing recombinant forms of TRAIL or TRAIL receptor agonists (e.g., receptor-specific mAb) for therapeutic purposes. In this review article we will describe the biochemical pathways used by TRAIL to induce different cell death programs. We will also summarize the clinical trials related to this pathway and discuss possible novel uses of TRAIL-related therapies. In recent years, the physiological importance of TRAIL has expanded beyond being a tumoricidal molecule to one critical for a number of clinical settings - ranging from infectious disease and autoimmunity to cardiovascular anomalies. We will also highlight some of these conditions where modulation of the TRAIL/TRAIL receptor system may be targeted in the future.

Apoptotic caspases prevent the induction of type I interferons by mitochondrial DNA

The mechanism by which cells undergo death determines whether dying cells trigger inflammatory responses or remain immunologically silent. Mitochondria play a central role in the induction of cell death, as well as in immune signaling pathways. Here, we identify a mechanism by which mitochondria and downstream proapoptotic caspases regulate the activation of antiviral immunity. In the absence of active caspases, mitochondrial outer membrane permeabilization by Bax and Bak results in the expression of type I interferons (IFNs). This induction is mediated by mitochondrial DNA-dependent activation of the cGAS/STING pathway and results in the establishment of a potent state of viral resistance. Our results show that mitochondria have the capacity to simultaneously expose a cell-intrinsic inducer of the IFN response and to inactivate this response in a caspase-dependent manner. This mechanism provides a dual control, which determines whether mitochondria initiate an immunologically silent or a proinflammatory type of cell death.

Role of type I interferon in inducing a protective immune response: perspectives for clinical applications

Type I IFNs (IFN-I) are antiviral cytokines endowed with many biological effects, including antitumor activity. Over the last 15 years, an ensemble of studies has revealed that these cytokines play a crucial role in the induction of a protective antitumor immune response. Early in vivo studies in mouse models have been instrumental for understanding the IFN-I-induced host-mediated mechanisms. IFN-α is currently recognized as a powerful inducer of the differentiation/activation of dendritic cells (DCs) and today IFN-α-conditioned DCs represent promising DC candidates for the development of therapeutic cancer vaccines. Moreover, data from pilot clinical trials support the concept of using IFN-α as an enhancer of the response of patients to cancer vaccines. Notably, endogenous IFN-I production does also play a critical role in the antitumor response to some chemotherapeutic agents. Thus, we can now envisage new strategies of clinical use of IFN-α, based on the injection of IFN-conditioned cells as well as the usage of these cytokines as cancer vaccine adjuvants, alone or in combination with other treatments (including epigenetic drugs) to induce an immunogenic cell death and a long lasting antitumor response.

Type I interferons as regulators of human antigen presenting cell functions

Type I interferons (IFNs) are pleiotropic cytokines, initially described for their antiviral activity. These cytokines exhibit a long record of clinical use in patients with some types of cancer, viral infections and chronic inflammatory diseases. It is now well established that IFN action mostly relies on their ability to modulate host innate and adaptive immune responses. Work in recent years has begun to elucidate the mechanisms by which type I IFNs modify the immune response, and this is now recognized to be due to effects on multiple cell types, including monocytes, dendritic cells (DCs), NK cells, T and B lymphocytes. An ensemble of results from both animal models and in vitro studies emphasized the key role of type I IFNs in the development and function of DCs, suggesting the existence of a natural alliance between these cytokines and DCs in linking innate to adaptive immunity. The identification of IFN signatures in DCs and their dysregulation under pathological conditions will therefore be pivotal to decipher the complexity of this DC-IFN interaction and to better exploit the therapeutic potential of these cells.

Toll-like receptor 3 recognizes incomplete stem structures in single-stranded viral RNA

Endosomal Toll-like receptor 3 (TLR3) serves as a sensor of viral infection and sterile tissue necrosis. Although TLR3 recognizes double-stranded RNA, little is known about structural features of virus- or host-derived RNAs that activate TLR3 in infection/inflammatory states. Here we demonstrate that poliovirus-derived single-stranded RNA segments harbouring stem structures with bulge/internal loops are potent TLR3 agonists. Functional poliovirus-RNAs are resistant to degradation and efficiently induce interferon-α/β and proinflammatory cytokines in human and mouse cells in a TLR3-dependent manner. The N- and C-terminal double-stranded RNA-binding sites of TLR3 are required for poliovirus-RNA-mediated TLR3 activation. Like polyriboinosinic:polyribocytidylic acid, a synthetic double-stranded RNA, these RNAs are internalized into cells via raftlin-mediated endocytosis and colocalized with TLR3. Raftlin-associated RNA uptake machinery and the TLR3 RNA-sensing system appear to recognize an appropriate topology of multiple RNA duplexes in poliovirus-RNAs. Hence, TLR3 is a sensor of extracellular viral/host RNA with stable stem structures derived from infection or inflammation-damaged cells.

Inborn errors of anti-viral interferon immunity in humans

The three types of interferon (IFNs) are essential for immunity against at least some viruses in the mouse model of experimental infections, type I IFNs displaying the broadest and strongest anti-viral activity. Consistently, human genetic studies have shown that type II IFN is largely redundant for immunity against viruses in the course of natural infections. The precise contributions of human type I and III IFNs remain undefined. However, various inborn errors of anti-viral IFN immunity have been described, which can result in either broad or narrow immunological and viral phenotypes. The broad disorders impair the response to (STAT1, TYK2) or the production of at least type I and type III IFNs following multiple stimuli (NEMO), resulting in multiple viral infections at various sites, including herpes simplex encephalitis (HSE). The narrow disorders impair exclusively (TLR3) or mostly (UNC-93B, TRIF, TRAF3) the TLR3-dependent induction of type I and III IFNs, leading to HSE in apparently otherwise healthy individuals. These recent discoveries highlight the importance of human type I and III IFNs in protective immunity against viruses, including the TLR3-IFN pathway in protection against HSE.

Oligodendroglia are limited in type I interferon induction and responsiveness in vivo

Type I interferons (IFNα/β) provide a primary defense against infection. Nevertheless, the dynamics of IFNα/β induction and responsiveness by central nervous system (CNS) resident cells in vivo in response to viral infections are poorly understood. Mice were infected with a neurotropic coronavirus with tropism for oligodendroglia and microglia to probe innate antiviral responses during acute encephalomyelitis. Expression of genes associated with the IFNα/β pathways was monitored in microglia and oligodendroglia purified from naïve and infected mice by fluorescent activated cell sorting. Compared with microglia, oligodendroglia were characterized by low basal expression of mRNA encoding viral RNA sensing pattern recognition receptors (PRRs), IFNα/β receptor chains, interferon sensitive genes (ISG), as well as kinases and transcription factors critical in IFNα/β signaling. Although PRRs and ISGs were upregulated by infection in both cell types, the repertoire and absolute mRNA levels were more limited in oligodendroglia. Furthermore, although oligodendroglia harbored higher levels of viral RNA compared with microglia, Ifnα/β was only induced in microglia. Stimulation with the double stranded RNA analogue poly I:C also failed to induce Ifnα/β in oligodendroglia, and resulted in reduced and delayed induction of ISGs compared with microglia. The limited antiviral response by oligodendroglia was associated with a high threshold for upregulation of Ikkε and Irf7 transcripts, both central to amplifying IFNα/β responses. Overall, these data reveal that oligodendroglia from the adult CNS are poor sensors of viral infection and suggest they require exogenous IFNα/β to establish an antiviral state.

Effects of interferon-beta therapy on elements in the antiviral immune response towards the human herpesviruses EBV, HSV, and VZV, and to the human endogenous retroviruses HERV-H and HERV-W in multiple sclerosis

Effects of treatment of multiple sclerosis patients with IFN-β on elements of the antiviral immune response to herpesviruses were analysed in a longitudinal study. We found significantly increased seroreactivity to EBV EBNA-1, and to VZV, in patients who did not respond to IFN-β therapy. We found no significant changes in seroreactivity to EBV EA, or to HSV. For the same patient cohort, we have previously demonstrated significant decreases in seroreactivities to envelope antigens for the two human endogenous retroviruses HERV-H and HERV-W, closely linked to efficacy of therapy. We further searched for correlations between seroreactivities to EBV, HSV, and VZV, and levels of mannan-binding lectin (MBL), and MBL-associated serine protease 3. We found no such correlations. Our results are in accord with recent reports of increased seroreactivity to EBV EBNA-1, and to VZV in active MS, and they support that the herpesviruses EBV and VZV together with HERV-H/HERV-W and the antiviral immune response may play a role in MS development.

Reduced interferon (IFN)-α conditioned by IFNA2 (-173) and IFNA8 (-884) haplotypes is associated with enhanced susceptibility to severe malarial anemia and longitudinal all-cause mortality

Severe malarial anemia (SMA) is a leading cause of pediatric morbidity and mortality in holoendemic Plasmodium falciparum transmission areas. Although dysregulation in cytokine production is an important etiology of SMA, the role of IFN-α in SMA has not been reported. As such, we investigated the relationship between IFN-α promoter polymorphisms [i.e., IFNA2 (A-173T) and IFNA8 (T-884A)], SMA, and functional changes in IFN-α production in children (n = 663; <36 months) residing in a holoendemic P. falciparum transmission region of Kenya. Children with SMA had lower circulating IFN-α than malaria-infected children without severe anemia (P = 0.025). Multivariate logistic regression analyses revealed that heterozygosity at -884 (TA) was associated with an increased risk of SMA [OR 2.80 (95 % CI 1.22-6.43); P = 0.015] and reduced IFN-α relative to wild type (TT; P = 0.038). Additional analyses demonstrated that carriage of the -173T/-884A (TA) haplotype was associated with increased susceptibility to SMA [OR 3.98 (95 % CI 1.17-13.52); P = 0.026] and lower IFN-α (P = 0.031). Follow-up of these children for 36 months revealed that carriers of TA haplotype had greater all-cause mortality than non-carriers (P < 0.001). Generation of reporter constructs showed that the IFNA8 wild-type -884TT exhibited higher levels of luciferase expression than the variant alleles (P < 0.001). Analyses of malaria-associated inflammatory mediators demonstrated that carriers of TA haplotype had altered production of IL-1β, MIG, and IL-13 compared to non-carriers (P < 0.050). Thus, variation at IFNA2 -173 and IFNA8 -884 conditions reduced IFN-α production, and increased susceptibility to SMA and mortality.

Interferon-α as antiviral and antitumor vaccine adjuvants: mechanisms of action and response signature

Interferon-α (IFN-α) are cytokines endowed with multiple biologic effects, including activities on cells of the immune system, which are important for inducing protective antiviral and antitumor responses. Studies in mouse models have been instrumental for understanding the immune adjuvant activity of these cytokines and some of their mechanisms of action. In particular, recent studies conducted on both mouse and human models suggest that IFN-α act as effective immune adjuvants for inducing antiviral and antitumor immunity and that the effects of IFN on the differentiation and activation of dendritic cells (DC) play an important role in the induction of protective responses. In spite of the long record of IFN-α clinical use, a few clinical trials have attempted to evaluate the efficacy of these cytokines used as vaccine adjuvants. Recently, studies on the IFN-α signature in cells from patients treated with IFN-α under different modalities and various clinical settings have provided important insights for understanding the in vivo mechanisms of the IFN immune adjuvant activity in humans and may contribute to the identification of molecular markers with a clinical response. These studies further support the interest of evaluating the clinical efficacy of IFN-α when used as a vaccine adjuvant and also suggest that the DC generated in vitro from monocytes in the presence of this cytokine can exhibit a special advantage for the development of effective therapeutic vaccination strategies in cancer patients.

Evolutionary genetic dissection of human interferons

As revealed by population genetic analyses, different human interferon genes evolved under distinct selective constraints and signatures of positive selection vary according to geographic region, suggesting that some sequence changes may have conferred an advantage by increasing resistance to viral infection.

Interferons (IFNs) are cytokines that play a key role in innate and adaptive immune responses. Despite the large number of immunological studies of these molecules, the relative contributions of the numerous IFNs to human survival remain largely unknown. Here, we evaluated the extent to which natural selection has targeted the human IFNs and their receptors, to provide insight into the mechanisms that govern host defense in the natural setting. We found that some IFN-α subtypes, such as IFN-α6, IFN-α8, IFN-α13, and IFN-α14, as well as the type II IFN-γ, have evolved under strong purifying selection, attesting to their essential and nonredundant function in immunity to infection. Conversely, selective constraints have been relaxed for other type I IFNs, particularly for IFN-α10 and IFN-ε, which have accumulated missense or nonsense mutations at high frequencies within the population, suggesting redundancy in host defense. Finally, type III IFNs display geographically restricted signatures of positive selection in European and Asian populations, indicating that genetic variation at these genes has conferred a selective advantage to the host, most likely by increasing resistance to viral infection. Our population genetic analyses show that IFNs differ widely in their biological relevance, and highlight evolutionarily important determinants of host immune responsiveness.

IFN-α as a vaccine adjuvant: recent insights into the mechanisms and perspectives for its clinical use

The IFN-α family are pleiotropic cytokines with the longest record of clinical use. Over the last decade, new biological effects of IFN-α on immune cells, including dendritic cells, have been described, supporting the concept that these cytokines can act as effective vaccine adjuvants. Recently, an important advance in our understanding of the mechanisms of interferon adjuvant activity has been achieved. Some clinical studies have been performed to assess the adjuvant activity in individuals immunized with preventive vaccines, showing variable results depending on interferon/vaccine formulation and vaccinated subjects. In spite of many data in animal models, little information is available on the possible advantage of utilizing IFN-α as an adjuvant for cancer vaccines in humans. Further clinical trials specifically designed to explore vaccine adjuvant activity are needed in order to define the best conditions for using IFN-α or IFN-α-conditioned dendritic cells for the development of therapeutic vaccines.

HCV infection and B-cell lymphomagenesis

Hepatitis C virus (HCV) has been recognized as a major cause of chronic liver diseases worldwide. It has been suggested that HCV infects not only hepatocytes but also mononuclear lymphocytes including B cells that express the CD81 molecule, a putative HCV receptor. HCV infection of B cells is the likely cause of B-cell dysregulation disorders such as mixed cryoglobulinemia, rheumatoid factor production, and B-cell lymphoproliferative disorders that may evolve into non-Hodgkin's lymphoma (NHL). Epidemiological data indicate an association between HCV chronic infection and the occurrence of B-cell NHL, suggesting that chronic HCV infection is associated at least in part with B-cell lymphomagenesis. In this paper, we aim to provide an overview of recent literature, including our own, to elucidate a possible role of HCV chronic infection in B-cell lymphomagenesis.

Transcriptional activators of human genes with programmable DNA-specificity

TAL (transcription activator-like) effectors are translocated by Xanthomonas bacteria into plant cells where they activate transcription of target genes. DNA target sequence recognition occurs in a unique mode involving a central domain of tandem repeats. Each repeat recognizes a single base pair in a contiguous DNA sequence and a pair of adjacent hypervariable amino acid residues per repeat specifies which base is bound. Rearranging the repeats allows the design of novel TAL proteins with predictable DNA-recognition specificities. TAL protein-based transcriptional activation in plant cells is mediated by a C-terminal activation domain (AD). Here, we created synthetic TAL proteins with designed repeat compositions using a novel modular cloning strategy termed “Golden TAL Technology”. Newly programmed TAL proteins were not only functional in plant cells, but also in human cells and activated targeted expression of exogenous as well as endogenous genes. Transcriptional activation in different human cell lines was markedly improved by replacing the TAL-AD with the VP16-AD of herpes simplex virus. The creation of TAL proteins with potentially any desired DNA-recognition specificity allows their versatile use in biotechnology.

Concomitant detection of IFNα signature and activated monocyte/dendritic cell precursors in the peripheral blood of IFNα-treated subjects at early times after repeated local cytokine treatments

BACKGROUND

Interferons alpha (IFNα) are the cytokines most widely used in clinical medicine for the treatment of cancer and viral infections. Among the immunomodulatory activities possibly involved in their therapeutic efficacy, the importance of IFNα effects on dendritic cells (DC) differentiation and activation has been considered. Despite several studies exploiting microarray technology to characterize IFNα mechanisms of action, there is currently no consensus on the core signature of these cytokines in the peripheral blood of IFNα-treated individuals, as well as on the existence of blood genomic and proteomic markers of low-dose IFNα administered as a vaccine adjuvant.

METHODS

Gene profiling analysis with microarray was performed on PBMC isolated from melanoma patients and healthy individuals 24 hours after each repeated injection of low-dose IFNα, administered as vaccine adjuvant in two separate clinical trials. At the same time points, cytofluorimetric analysis was performed on CD14+ monocytes, to detect the phenotypic modifications exerted by IFNα on antigen presenting cells precursors.

RESULTS

An IFNα signature was consistently observed in both clinical settings 24 hours after each repeated administration of the cytokine. The observed modulation was transient, and did not reach a steady state level refractory to further stimulations. The molecular signature observed ex vivo largely matched the one detected in CD14+ monocytes exposed in vitro to IFNα, including the induction of CXCL10 at the transcriptional and protein level. Interestingly, IFNα ex vivo signature was paralleled by an increase in the percentage and expression of costimulatory molecules by circulating CD14+/CD16+ monocytes, indicated as natural precursors of DC in response to danger signals.

CONCLUSIONS

Our results provide new insights into the identification of a well defined molecular signature as biomarker of IFNα administered as immune adjuvants, and for the characterization of new molecular and cellular players, such as CXCL10 and CD14+/CD16+ cells, mediating and possibly predicting patient response to these cytokines.

Antiviral responses induced by the TLR3 pathway

Antiviral responses are successively induced in virus-infected animals, and include primary innate immune responses such as type I interferon (IFN) and cytokine production, secondary natural killer (NK) cell responses, and final cytotoxic T lymphocyte (CTL) responses and antibody production. The endosomal Toll-like receptors (TLRs) and cytoplasmic RIG-I-like receptors (RLRs), which recognize viral nucleic acids, are responsible for virus-induced type I IFN production. RLRs are expressed in most tissues and cells and are primarily implicated in innate immune responses against various viruses through type I IFN production, whereas nucleic acid-sensing TLRs, TLRs 3, 7, 8 and 9, are expressed on the endosomal membrane of dendritic cells (DCs) and play distinct roles in antiviral immunity. TLR3 recognizes viral double-stranded RNA taken up into the endosome and serves to protect the host against viral infection by the induction of a range of responses including type I IFN production and DC-mediated activation of NK cells and CTLs, although the deteriorative role of TLR3 has also been reported in some virus infections. Here, we review the current knowledge on the role of TLR3 during viral infection, and the current understanding of the TLR3-signalling cascade that operates via the adaptor protein TICAM-1 (also called TRIF).

IL-15 and type I interferon are required for activation of tumoricidal NK cells by virus-infected dendritic cells

There is increasing evidence that natural killer (NK) cells play an important role in antitumor immunity following dendritic cell (DC) vaccination. Little is known, however, about the optimal stimulation of DCs that favors NK activation in tumor-bearing hosts. In this study, we demonstrate that treatment with toll-like receptor (TLR) ligands and infection with a mutant vesicular stomatitis virus (VSV-ΔM51) both induced DC maturation. Further, inoculation of these DCs led to robust NK-mediated protection against tumor challenge. Strikingly, only VSV-ΔM51-infected DCs were capable of suppressing the growth of established tumors, suggesting that additional signals provided by viral infection may be required to activate tumoricidal NK cells in tumor-bearing hosts. VSV-ΔM51 infection of DCs induced greater type I interferon (IFN I) production than TLR ligand treatment, and disruption of the IFN I pathway in DCs eliminated their ability to induce NK activation and tumor protection. However, further studies indicated that IFN I alone was not sufficient to activate NK cells, especially in the presence of a tumor, and DC-derived IL-15 was additionally required for tumoricidal NK activation. These results suggest that induction of IFN I by VSV-ΔM51 allows DCs to overcome tumor-associated immunosuppression and facilitate IL-15-mediated priming of tumoricidal NK cells. Thus, the mode of DC maturation should be carefully considered when designing DC-based cancer immunotherapies.

Does cytokine signaling link sphingolipid metabolism to host defense and immunity against virus infections?

Sphingosine 1-phosphate (S1P)-metabolizing enzymes regulate the level of bioactive sphingolipids that have curative potential. Recently, S1P-metabolizing enzymes such as sphingosine kinase 1 and S1P lyase were shown to regulate influenza virus replication and the virus-induced cytopathogenicity. The mechanism appeared to employ a JAK/STAT type I interferon signaling pathway that induces anti-viral status. Further, sphingosine analogs altered cytokine responses upon influenza virus infection. This article focuses on recent discoveries about the sphingolipid system that influences on host protection from viral virulence and the involvement of cytokine signaling in its underlying mechanisms. Deciphering the steps of this pathway could help us envision how the modulation of sphingolipid metabolism can be applied as a therapeutic approach to overcome infectious diseases.

The interferon-alpha signature of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic multisystem autoimmune disorder where interplay of environmental and genetic risk factors leads to progressive loss of tolerance to nuclear antigens over time, finally culminating in clinical disease. The heterogeneity of clinical manifestations and the disease's unpredictable course characterized by flares and remissions are very likely a reflection of heterogeneity at the origin of disease, with a final common pathway leading to loss of tolerance to nuclear antigens. Impaired clearance of immune complexes and apoptotic material and production of autoantibodies have long been recognized as major pathogenic events in this disease. Over the past decade the type I interferon cytokine family has been postulated to play a central role in SLE pathogenesis, by promoting feedback loops progressively disrupting peripheral immune tolerance and driving disease activity. The identification of key molecules involved in the pathogenesis of SLE will not only improve our understanding of this complex disease, but also help to identify novel targets for biological intervention.

Type I interferon modulates the battle of host immune system against viruses

Type I interferon (IFN), as its name implies, 'interferes' with virus replication by activating numerous genes. Further, virus-induced type I IFN regulates the magnitude and functions of cells directing the host immune system. Importantly, recent exploration into how type I IFN operates following virus infection has advanced our understanding of its role with respect to modulation of host innate and adaptive immune responses. Such activities include the activation of antigen-presenting dendritic cells and the localization, expansion or differentiation of virus-specific T lymphocytes and antibody-producing B lymphocytes. However, type I IFN not only benefits the host but can also induce unnecessary or extremely pathogenic immune responses. This review focuses on such interactions and the manner in which type I IFN induces dynamic changes in the host immune network, particularly adaptive immune responses to viral invasion. Manipulating the type I IFN-mediated host immune response during virus infections could provide new immunotherapeutic interventions to remedy viral diseases and implement more effective and sustainable type I IFN therapy.

Recent advances on the immunomodulatory effects of IFN-alpha: implications for cancer immunotherapy and autoimmunity

Interferons alpha (IFNs-alpha) are pleiotropic cytokines belonging to the type I IFN family, originally described for their antiviral activity. These cytokines exhibit a long record of clinical use in patients with some types of cancer and viral diseases. Notably, certain autoimmune disorders have been postulated to be mediated by endogenous IFN-alpha and are often observed in some IFN-treated patients. IFN-alpha can induce multiple biological effects, including induction/promotion of apoptosis and inhibition of cell growth. In addition, these cytokines promote the differentiation and activity of host immune cells. Early studies in mouse tumor models showed the importance of host immune mechanisms in the generation of a long-lasting antitumor response after injection of the animals with either IFN or tumor cells genetically modified for IFN-alpha production. Several studies have shown that IFN-alpha can induce the rapid differentiation of monocytes into highly activated dendritic cells (DCs). Of note, these DCs (IFN-DCs) are particularly effective in taking up complex antigens and inducing T- and B-cell immunity. The ensemble of these results suggests that IFN-DCs can play a role in the generation of antitumor T-cell immunity, pointing out that these cells could be successfully used in strategies of cancer immunotherapy. Likewise, IFN-alpha-DC interactions could also play a role in the pathogenesis of some autoimmune disorders, often associated with IFN-alpha treatment. All this reveals the complexity of the IFN-alpha-DC interactions under normal and pathological conditions and stimulates further studies for identifying optimal modalities in either using these cytokines or controlling their production/action in patients.

Encapsulation of mesenchymal stem cells from Wharton's jelly in alginate microbeads

The description of a microencapsulation procedure for Wharton's jelly mesenchymal stem cells (WJMSCs) is reported. The applied method is based on the generation of monodisperse droplets by a vibrational nozzle. An ionic alginate encapsulation procedure was utilized for the microbeads hardening. Different experimental parameters were analyzed, including frequency and amplitude of vibration, polymer pumping rate, and distance between the nozzle and the gelling bath. The produced barium-alginate microbeads were characterized by excellent morphological characteristics as well as a very narrow size distribution. The microencapsulation procedure did not alter the morphology and viability of the encapsulated WJMSCs. In addition, the current paper reports the functional properties in terms of secretive profiles of both free and encapsulated WJMSCs. The analyzed factors were members of the family of interleukins, chemokines, growth factors, and soluble forms of adhesion molecules. These experiments showed that despite encapsulation, most of the proteins analyzed were secreted both by the free and encapsulated cells, even if in a different extent. In conclusion, the described encapsulation procedure represents a promising strategy to utilize WJMSCs for possible in vivo applications in tissue engineering and biomedicine.

Type I interferon signaling contributes to chronic inflammation in a murine model of silicosis

Lung disorders induced by inhaled inorganic particles such as crystalline silica are characterized by chronic inflammation and pulmonary fibrosis. Here, we demonstrate the importance of type I interferon (IFN) in the development of crystalline silica-induced lung inflammation in mice, revealing that viruses and inorganic particles share similar signaling pathways. We found that instillation of silica is followed by the upregulation of IFN-beta and IRF-7 and that granulocytes (GR1(+)) and macrophages/dendritic cells (CD11c(+)) are major producers of type I IFN in response to silica. Two months after silica administration, both IFNAR- and IRF-7-deficient mice produced significantly less pulmonary inflammation and chemokines (KC and CCL2) than competent mice but developed similar lung fibrosis. Our data indicate that type I IFN contributes to the chronic lung inflammation that accompanies silica exposure in mice. Type I IFN is, however, dispensable in the development of silica-induced acute lung inflammation and pulmonary fibrosis.

Murine toll-like receptor 2 activation induces type I interferon responses from endolysosomal compartments

Background

Toll-like receptors (TLRs) are among the first-line sentinels for immune detection and responsiveness to pathogens. The TLR2 subfamily of TLRs (TLR1, TLR2, TLR6) form heterodimers with each other and are thus able to recognize a broad range of components from several microbes such as yeast, Gram-positive bacteria and protozoa. Until now, TLR2 activation by bacterial ligands has long been associated with pro-inflammatory cytokines but not type I interferon responses.

Methodology/Principal Findings

Using a variety of transgenic mice, here we provide in vivo and in vitro data showing that TLR2 activation does in fact induce interferon-beta and that this occurs via MyD88-IRF1 and -IRF7 pathways. Interestingly, by microscopy we demonstrate that although a cell surface receptor, TLR2 dependent induction of type I interferons occurs in endolysosomal compartments where it is translocated to upon ligand engagement. Furthermore, we could show that blocking receptor internalization or endolysosomal acidification inhibits the ability of TLR2 to trigger the induction type I interferon but not pro-inflammatory responses.

Conclusion/Significance

The results indicate that TLR2 activation induces pro-inflammatory and type I interferon responses from distinct subcellular sites: the plasma membrane and endolysosomal compartments respectively. Apart from identifying and characterizing a novel pathway for induction of type I interferons, the present study offers new insights into how TLR signaling discriminates and regulates the nature of responses to be elicited against extracellular and endocytosed microbes. These findings may also have clinical implication. Excessive production of pro-inflammatory cytokines and type I IFNs following activation of TLRs is a central pathologic event in several hyper-inflammatory conditions. The discovery that the induction of pro-inflammatory and type I IFN responses can be uncoupled through pharmacological manipulation of endolysosomal acidification suggests new avenues for potential therapeutic intervention against inflammations and sepsis.

Overview of the biology of type I interferons

Type I interferons are pleiotropic cytokines with antiviral, antitumor and immunoregulatory functions. An aspect of their complex biology is the paradox that, depending on context, type I interferons can be anti-inflammatory and tissue protective or can be proinflammatory and promote autoimmunity. Along these lines, the activation of type I interferon pathways is effective in suppressing disease activity in patients with multiple sclerosis and in animal models of arthritis and colitis, while there is an expectation that blockade of the same pathways will be beneficial in the treatment of patients with systemic lupus erythematosus.

Recombinant interferon-alpha2b added to oral cyclophosphamide either as induction or maintenance in treatment-naive follicular lymphoma: final analysis of CALGB 8691

Recombinant interferon alpha-2b (IFN-alpha2) has direct and indirect antiproliferative effects in lymphoma, and may augment cytotoxicity when combined with chemotherapy. CALGB 8691 is a randomized study of daily oral cyclophosphamide (CPA) at 100 mg/m2 with or without IFN-alpha2 at 2 x 106 IU/m2 three times per week, followed by a second randomization between IFN-alpha2 maintenance (2 x 106 IU/m2 three times weekly) versus observation in treatment-naïve patients with follicular lymphoma (FL). Five hundred eighty-one patients were randomized to either CPA (n = 293) or CPA plus IFN-alpha2 (n = 288). One hundred five responding patients were randomized to observation and 99 to maintenance IFN-alpha2. With a median follow-up of 11.5 years, the median event-free and overall survival (OS) for CPA induction alone were 2.5 years (95% CI 2.2, 3.0) and 9 years (95% CI 7.7, 10.2), compared to 2.4 years (95% CI 2.1, 3.1) and 8.4 years (95% CI 7.5, 11.1) for the combination arm (p = NS). Patients with a partial response (PR) and randomized to observation had the worst outcome (event-free survival (EFS) 1.8 years versus 3.9 years; p = 0.002). Patients with a PR randomized to IFN-alpha2 had a similar EFS to compared to patients with complete response (CR), but this did not translate into a survival advantage. Myelosuppression was increased in IFN-alpha2-containing arms. Despite the small benefit in EFS in patients with PR randomized to IFN-alpha2 maintenance, we conclude that the addition of low dose IFN-alpha2 did not significantly improve the response rate, duration of response, event-free, or OS obtained with single-agent daily oral CPA in patients with previously untreated FL.

Effects of interferon-beta therapy on innate and adaptive immune responses to the human endogenous retroviruses HERV-H and HERV-W, cytokine production, and the lectin complement activation pathway in multiple sclerosis

The effects of treatment of multiple sclerosis patients with IFN-beta on elements in the innate and adaptive immune response were analysed in a longitudinal study. We demonstrate significant decreases in anti-Envelope antibody reactivity for the two closely related Gammaretroviral human endogenous retroviruses (HERVs), HERV-H and HERV-W, as a consequence of IFN-beta therapy, closely linked to efficacy of therapy/low disease activity. We also show strong indications of a protective effect of high levels of two components in the innate pathogen-associated molecular pattern recognition: mannan-binding lectin (MBL), and MBL-associated serine protease 3 (MASP-3). Serum levels of typical Th1- and Th2-related, MS-relevant cytokines were also monitored. Overall both Th1- and Th2-associated cytokines were modestly, albeit significantly up-regulated, notably IL-2 and TNF-alpha (MS patients with inactive disease), as well as IL-4 and, to some extent IL-10 (no increase in IL-10 for MS patients with active disease (non-responders)). We found no overall changes in Th1/Th2 ratios. Our results support that HERV-H/HERV-W and the antiviral immune response may play a role in MS development, and that these HERVs have potential as biomarkers for disease activity.

A new method to produce monoPEGylated dimeric cytokines shown with human interferon-α2b

We have adapted the dock-and-lock (DNL) method into a novel PEGylation technology using human interferon-α2b (IFN-α2b) as an example. Central to DNL is a pair of distinct protein domains involved in the natural association between cAMP-dependent protein kinase (PKA) and A-kinase anchoring proteins (AKAPs). These domains serve as linkers for site-specific conjugation of poly(ethylene glycol) (PEG) to a dimeric form of IFN-α2b. The combination of a fusion protein comprising IFN-α2b and the dimerization-and-docking domain (DDD) of PKA with a PEG-derivatized anchoring domain (AD) of an interactive AKAP results in facile formation of a trimeric complex containing two copies of IFN-α2b and a single site-specifically linked PEG chain. Three such monoPEGylated dimers of IFN-α2b have been generated, the first with a 20 kDa linear PEG, referred to as α2b-362, the second with a 30 kDa linear PEG (α2b-413), and the third with a 40 kDa branched PEG (α2b-457). All three retained antiviral and antitumor activity in vitro and showed improved pharmacokinetic properties in mice, which translated into potent and prolonged therapeutic efficacy in the Daudi human lymphoma xenograft model. We anticipate wide applicability of the DNL method for developing long-acting therapeutics that are dimeric and monoPEGylated with the increased bioavailability allowing for less frequent dosing.

Bacterial recognition by TLR7 in the lysosomes of conventional dendritic cells

Little is known of how and where bacterial recognition triggers the induction of type I interferon. Whether the type of recognition receptor used in these responses is determined by the subcellular location of bacteria is not understood. Here we show that phagosomal bacteria such as group B streptococcus, but not cytosolic bacteria, potently induced interferon in conventional dendritic cells by a mechanism that required Toll-like receptor 7, the adaptor MyD88 and the transcription factor IRF1, all of which localized together with bacterial products in degradative vacuoles bearing lysosomal markers. Thus, this cell type-specific recognition pathway links lysosomal recognition of bacterial RNA with a robust, host-protective interferon response.

Small silencing RNAs: an expanding universe

Since the discovery in 1993 of the first small silencing RNA, a dizzying number of small RNA classes have been identified, including microRNAs (miRNAs), small interfering RNAs (siRNAs) and Piwi-interacting RNAs (piRNAs). These classes differ in their biogenesis, their modes of target regulation and in the biological pathways they regulate. There is a growing realization that, despite their differences, these distinct small RNA pathways are interconnected, and that small RNA pathways compete and collaborate as they regulate genes and protect the genome from external and internal threats.

Hostile communication of measles virus with host innate immunity and dendritic cells

Following measles virus (MV) infection, host innate immune responses promptly operate to purge the virus. Detection of alerting measles viral components or replication intermediates by pattern-recognizing host machinery of Toll-like receptors and RNA helicases triggers signaling to synthesize array of anti-viral and immunoregulatory molecules, including type I interferon (IFN). Diverse subtypes of dendritic cells (DCs) play pivotal roles in both host innate immunity on the primary MV-infected site and initiating adaptive immune responses on secondary lymphoid tissues. Responding to the predictable host immune responses, MV appears to have devised multiple strategies to evade, suppress, or even utilize host innate immunity and DC responses. This review focuses on versatile actions of MV-induced type I IFNs causing beneficial or deleterious influence on host immunity and the interplay between MV and heterogeneous DCs at distinct locations.

Construction and expression of a novel bioactive IFN-alpha2b/CM4 fusion protein in Escherichia coli

Human interferon alpha2b (IFN-alpha2b) is a pleiotropic cytokine used for the treatment of various cancers. Antibacterial peptide CM4 is a small peptide that can strongly inhibit many kinds of bacteria, fungi, and tumor cells, but it does no harm to normal cells. Here, we describe a protein expression system for the production of IFN-alpha2b/CM4 fusion protein in insoluble form in Escherichia coli, coupled to an efficient dialysis refolding and histidine-tag purification protocol. The expressed IFN-alpha2b/CM4 fusion protein not only displays significantly improved antitumor activity, but also retains the antibacterial-antifungal activity of CM4.

Inborn errors of interferon (IFN)-mediated immunity in humans: insights into the respective roles of IFN-alpha/beta, IFN-gamma, and IFN-lambda in host defense

Interferon (IFN) was originally identified as a substance 'interfering' with viral replication in vitro. The first IFNs to be identified were classified as type I IFNs (IFN-alpha/beta and related molecules), two other types have since been identified: type II IFN (IFN-gamma) and type III IFNs (IFN-lambda). Each IFN binds to one of three type-specific receptors. In the mouse model of experimental infections in vivo, IFN-alpha/beta are essential for immunity to most viruses tested, whereas IFN-gamma is important for immunity to a smaller number of viruses, together with bacteria, fungi, and parasites, consistent with IFN-gamma acting as the 'macrophage activating factor.' The precise role of IFN-lambda remains unclear. In recent years, inborn errors affecting the production of, or the response to, IFNs have been reported in human patients, shedding light onto the function of IFNs in natura. Disorders of IFN-gamma production, caused by IL12B, IL12RB1, and specific NEMO mutations, or of IFN-gamma responses, caused by IFNGR1, IFNGR2, and dominant STAT1 mutations, confer predisposition to mycobacterial disease in patients resistant to most viruses. By contrast, disorders of IFN-alpha/beta and IFN-lambda production, caused by UNC93B1 and TLR3 mutations, confer predisposition to herpes simplex encephalitis (HSE) in otherwise healthy patients. Consistently, patients with impaired responses to IFN-alpha/beta, IFN-gamma, and presumably IFN-lambda (carrying recessive mutations in STAT1), or with impaired responses to IFN-alpha/beta and impaired IFN-gamma production (carrying mutations in TYK2), or with impaired production of IFN-alpha/beta, IFN-gamma, and IFN-lambda (carrying specific mutations in NEMO), are vulnerable to mycobacterial and viral infections, including HSE. These experiments of nature suggest that the three types of IFNs play at least two different roles in host defense. IFN-gamma is essential for anti-mycobacterial immunity, whereas IFN-alpha/beta and IFN-lambda are essential for anti-viral immunity. Future studies in humans aim to define the specific roles of IFN-alpha/beta and IFN-lambda types and individual molecules in host defense in natura.

PCR-based simultaneous analysis of the interferon-alpha family reveals distinct kinetics for early interferons

Here we describe a PCR-based analysis system that allows the simple simultaneous assessment of murine interferons (IFN)-alpha and IFN-beta induction in a single reaction. In this analysis, the so-called early IFN-alpha4 can be distinguished from the so-called late IFN-nonalpha4 by employing a primer mixture that amplifies a part of the IFN-alpha genes in which IFN-alpha4 exhibits a deletion of 15 nucleotides compared to IFN-nonalpha4. By including a final denaturation and a slow cooling step at the end of the PCR procedure, hybrid formation was avoided that regularly occurred when standard protocols were used. Separation of the amplification products on 4.5% agarose gels allowed the comparative assessment of the classical type I IFNs. Using this analysis system, we could show that in immortalized adult fibroblasts, IFN-beta is induced first and the two types of IFN-alpha are induced later and simultaneously. When similar fibroblasts derived from mice that lack IFN-beta were tested, the IFN response was delayed. However, now IFN-alpha4 appeared first and apparently induced the cascade of IFN-nonalpha4. This confirms the role of IFN-beta as master regulator of the normal IFN response.

Activation of pattern recognition receptor-mediated innate immunity inhibits the replication of hepatitis B virus in human hepatocyte-derived cells

Recognition of virus infections by pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs), retinoic acid-inducible gene I (RIG-I), and melanoma differentiation associated gene 5 (MDA5), activates signaling pathways, leading to the induction of inflammatory cytokines that limit viral replication. To determine the effects of PRR-mediated innate immune response on hepatitis B virus (HBV) replication, a 1.3mer HBV genome was cotransfected into HepG2 or Huh7 cells with plasmid expressing TLR adaptors, myeloid differentiation primary response gene 88 (MyD88), and TIR-domain-containing adaptor-inducing beta interferon (TRIF), or RIG-I/MDA5 adaptor, interferon promoter stimulator 1 (IPS-1). The results showed that expressing each of the three adaptors dramatically reduced the levels of HBV mRNA and DNA in both HepG2 and Huh7 cells. However, HBV replication was not significantly affected by treatment of HBV genome-transfected cells with culture media harvested from cells transfected with each of the three adaptors, indicating that the adaptor-induced antiviral response was predominantly mediated by intracellular factors rather than by secreted cytokines. Analyses of involved signaling pathways revealed that activation of NF-kappaB is required for all three adaptors to elicit antiviral response in both HepG2 and Huh7 cells. However, activation of interferon regulatory factor 3 is only essential for induction of antiviral response by IPS-1 in Huh7 cells, but not in HepG2 cells. Furthermore, our results suggest that besides NF-kappaB, additional signaling pathway(s) are required for TRIF to induce a maximum antiviral response against HBV. Knowing the molecular mechanisms by which PRR-mediated innate defense responses control HBV infections could potentially lead to the development of novel therapeutics that evoke the host cellular innate antiviral response to control HBV infections.

[Interferon-alpha: a key cytokine in systemic lupus erythematosus pathogenesis]

Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by a chronic inflammation affecting multiple tissues and the production of antibodies directed against nuclear antigens. Leading observations in patients suggested years ago that interferon-alpha (IFNalpha) was involved in SLE pathogenesis. These observations have now been confirmed in SLE-prone mice. New promising therapeutic strategies, aiming at neutralizing IFNalpha or its effects, are currently under development.

The orthopoxvirus type I IFN binding protein is essential for virulence and an effective target for vaccination

Nonliving antiviral vaccines traditionally target proteins expressed at the surface of the virion with the hope of inducing neutralizing antibodies. Orthopoxviruses (OPVs), such as the human smallpox virus and the mouse-equivalent ectromelia virus (ECTV; an agent of mousepox), encode immune response modifiers (IRMs) that can increase virulence by decreasing the host immune response. We show that one of these IRMs, the type I interferon (IFN) binding protein (bp) of ECTV, is essential for ECTV virulence and is a natural target of the antibody response. More strikingly, we demonstrate that immunization with recombinant type I IFN bp protects mice from lethal mousepox. Collectively, our experiments have important implications for our understanding of the role of IRMs in OPV virulence and of type I IFNs in OPV infections. Furthermore, our work provides proof of concept that effective antiviral vaccines can be made to prevent disease by targeting virulence factors as an alternative to the traditional approach that attempts to prevent infection by virus neutralization.

Genetic susceptibility to herpes simplex virus 1 encephalitis in mice and humans

PURPOSE OF REVIEW

Herpes simplex encephalitis is a rare complication of herpes simplex virus 1 infection that strikes otherwise healthy individuals. Its pathogenesis has long remained elusive. We highlight the investigations dealing with the genetic basis of herpes simplex encephalitis in mice and humans.

RECENT FINDINGS

Mouse models have revealed the impact of various host genes on protective immunity to herpes simplex encephalitis through strain-dependent variability (forward genetics) and via targeted knockouts (reverse genetics). These studies established in particular the crucial role of IFNalpha/beta in immunity to herpes simplex virus 1, paving the way towards the elucidation of the genetic cause of human herpes simplex encephalitis. Two children with rare, specific STAT1 or NEMO mutations displayed a broad impairment of IFNalpha/beta and IFNlambda-mediated immunity and predisposition to several infectious diseases including herpes simplex encephalitis. In contrast, children with UNC93B1 and TLR3 mutations displayed a selective impairment of dsRNA-induced IFNalpha/beta and IFNlambda production and predisposition to isolated herpes simplex encephalitis.

SUMMARY

Herpes simplex encephalitis results from a series of monogenic primary immunodeficiencies that impair the TLR3 and UNC-93B-dependent production of IFNalpha/beta and IFNlambda in the central nervous system, at least in a fraction of children. This is not only crucial for the understanding of immunity to herpes simplex virus 1, but also for the diagnosis and treatment of herpes simplex encephalitis.

Comparable potency of IFNalpha2 and IFNbeta on immediate JAK/STAT activation but differential down-regulation of IFNAR2

Type I IFNs (interferons) (IFNalpha/beta) form a family of related cytokines that control a variety of cellular functions through binding to a receptor composed of IFNAR (IFNalpha receptor subunit) 1 and 2. Among type I IFNs, the alpha2 and beta subtypes exhibit a large difference in their binding affinities to IFNAR1, and it was suggested that high concentrations of IFNAR1 may compensate for its low intrinsic binding affinity for IFNalpha2. We tested whether receptor-proximal signalling events are sensitive to IFNAR1 surface concentration by investigating the relationship between relative IFNAR1/IFNAR2 surface levels and IFNalpha2 and IFNbeta signalling potencies in several cell lines. For this, we monitored the activation profile of JAK (Janus kinase)/STAT (signal transducer and activator of transcription) proteins, measured basal and ligand-induced surface decay of each receptor subunit and tested the effect of variable IFNAR1 levels on IFNalpha2 signalling potency. Our data show that the cell-surface IFNAR1 level is indeed a limiting factor for assembly of the functional complex, but an increased concentration of it does not translate into an IFNalpha/beta differential JAK/STAT signalling nor does it change the dynamics of the engaged receptor. Importantly, however, our data highlight a differential effect upon routing of IFNAR2. Following binding of IFNalpha2, IFNAR2 is internalized, but, instead of being routed towards degradation as it is when complexed to IFNbeta, it recycles back to the cell surface. These observations suggest strongly that the stability and the intracellular lifetime of the ternary complex account for the differential control of IFNAR2. Moreover, the present study opens up the attractive possibility that endosomal-initiated signalling may contribute to IFNalpha/beta differential bioactivities.

Toxicity as a result of immunostimulation by biologics

The immune system has evolved highly effective mechanisms of surveillance and defense against foreign pathogens, and is also thought to act in surveillance and suppression of cancer. Thus, a predominant goal of immune system-based therapies is to normalize or enhance the host immune response in the areas of infectious disease and oncology. This review considers general approaches used for therapeutic immunostimulation, alterations in immune response mechanisms that occur with these treatments and the syndromes that commonly arise as a result of these changes. Because nonclinical studies of these therapies are conducted in animal models as the basis for predicting potential human toxicities, this review also considers the value of nonclinical testing to predict human toxicity.

Directional responses following recombinant cytokine stimulation of rainbow trout (Oncorhynchus mykiss) RTS-11 macrophage cells as revealed by transcriptome profiling

Background

The early stages of the immune response are regulated by key cytokines including both interleukin 1β (IL-1β) and interferon-γ (IFN-γ) which stimulate panels of responsive genes via conserved signal transduction pathways. To further our understanding of the transcriptional response to these cytokines in lower vertebrates we have utilized microarray analysis to characterize the transcriptional response to recombinant rainbow trout IL-1β and IFN-γ in the trout macrophage cell line RTS-11.

Results

RNA was extracted from stimulated or control cells following 6 h incubation and used to hybridize to a salmonid cDNA microarray containing 16,006 different genes. Analysis of the arrays revealed mRNA transcripts that were differentially expressed as a result of exposure to the recombinant proteins, with some responses common for both cytokines. In general the recombinant IL-1β elicited a response where genes involved in the acute phase response were up-regulated, whilst the recombinant IFN-γ induced strong up-regulation of genes involved in the MHC class I antigen presentation pathway. Key genes were chosen that were differentially regulated and analysed by real time PCR at additional time points, up to 48 h following stimulation. This allowed a deeper insight into the kinetics of the response to the cytokines in this cell line.

Conclusion

We demonstrated that in fish both rIL-1β and rIFN-γ stimulated discrete panels of mRNA transcripts which indicted the cells were being directed towards different cellular functions, with IL-β inducing genes involved in the inflammatory response, whereas IFN-γ induced genes associated with antigen presentation.

IFN- and Novel Strategies of Combination Therapy for Cancer

Interferons-alpha (IFN-alpha) are a group of cytokines belonging to type I IFN family, which exert multiple biological effects, including antiviral and antitumor activities in patients with defined types of cancer and viral diseases. Early studies in mouse tumor models have shown the importance of host immune mechanisms in the generation of a long-lasting antitumor response after type I IFN treatment. Recent studies have revealed new immunomodulatory effects of IFN-alpha, including activities on T cells and dendritic cells (DCs), which may explain the immune correlates frequently observed in some categories of cancer patients responding to IFN-alpha therapy. Of note, new knowledge has recently been generated on the mechanisms of action of some chemotherapeutic agents, such as cyclophosphamide (CTX), on cells of the immune system, whose effects can now be exploited for the design of more effective combination therapies. On the whole, the new strategies based on IFN-alpha include the in vivo use of these cytokines as immune adjuvants of cancer vaccines, their in vitro use to generate highly active DC-based vaccines, and the combination of certain chemotherapy regimens with IFN-alpha-adjuvanted cancer vaccines.