Type I interferon differential therapy for erythroleukemia: specificity of STAT activation

The Antiviral Effects of Heat-Killed Lactococcus lactis Strain Plasma Against Dengue, Chikungunya, and Zika Viruses in Humans by Upregulating the IFN-α Signaling Pathway

The growing risk of contracting viral infections due to high-density populations and ecological disruptions, such as climate change and increased population mobility, has highlighted the necessity for effective antiviral treatment and preventive measures against Dengue virus (DENV), Chikungunya virus (CHIKV), and Zika virus (ZIKV). Recently, there has been increasing attention on the use of probiotics as a potential antiviral option to reduce virus infections. The present study aimed to assess the immunomodulatory effects of heat-killed Lactococcus lactis strain plasma (LC-Plasma) on peripheral blood mononuclear cells (PBMCs) and its subsequent antiviral response against DENV, CHIKV, and ZIKV. To evaluate the immunomodulatory effects of LC-Plasma on PBMCs isolated from healthy individuals, PBMCs were cultured at a density of 2 × 105 cells/well and stimulated with 10 µg/mL of LC-Plasma. LC-plasma-stimulated PBMCs demonstrated elevated interferon-alpha (IFN-α) production and cluster of differentiation 86 (CD86) and human leukocyte antigen-DR isotype (HLA-DR) upregulation, potentially linked to plasmacytoid dendritic cell (pDC) activation. The replication of DENV, CHIKV, and ZIKV was dose-dependently inhibited when Huh-7 cells were stimulated with LC-Plasma-stimulated PBMC supernatant (LCP Sup). IFN-stimulated gene (ISG) expression, including IFN-stimulated gene 15 (ISG15), IFN-stimulated exonuclease gene 20 (ISG20), IFN-induced transmembrane protein 1 (IFITM-1), myxovirus resistance protein A (MxA), and radical S-adenosyl methionine domain-containing protein 2 (RSAD2), was significantly upregulated in LCP Sup-stimulated Huh-7 cells. Findings from this study indicate that LC-Plasma has the potential to induce IFN-α production, leading to an enhancement in the expression of ISGs and contributing to a broad-spectrum antiviral response. Thus, LC-Plasma may serve as a rational adjunctive treatment to ameliorate viral diseases, warranting future clinical trials.

IFNα Subtypes in HIV Infection and Immunity

Type I interferons (IFN), immediately triggered following most viral infections, play a pivotal role in direct antiviral immunity and act as a bridge between innate and adaptive immune responses. However, numerous viruses have evolved evasion strategies against IFN responses, prompting the exploration of therapeutic alternatives for viral infections. Within the type I IFN family, 12 IFNα subtypes exist, all binding to the same receptor but displaying significant variations in their biological activities. Currently, clinical treatments for chronic virus infections predominantly rely on a single IFNα subtype (IFNα2a/b). However, the efficacy of this therapeutic treatment is relatively limited, particularly in the context of Human Immunodeficiency Virus (HIV) infection. Recent investigations have delved into alternative IFNα subtypes, identifying certain subtypes as highly potent, and their antiviral and immunomodulatory properties have been extensively characterized. This review consolidates recent findings on the roles of individual IFNα subtypes during HIV and Simian Immunodeficiency Virus (SIV) infections. It encompasses their induction in the context of HIV/SIV infection, their antiretroviral activity, and the diverse regulation of the immune response against HIV by distinct IFNα subtypes. These insights may pave the way for innovative strategies in HIV cure or functional cure studies.

Sex-dependent differences in type I IFN-induced natural killer cell activation

Natural killer (NK) cells are important antiviral effector cells and also involved in tumor clearance. NK cells express IFNAR, rendering them responsive to Type I IFNs. To evaluate Type I IFN-mediated modulation of NK cell functions, individual Type I IFNs subtypes were assessed for their ability to activate NK cells. Different Type I IFN subtypes displayed a broad range in the capacity to induce and modulate NK cell activation and degranulation, measured by CD69 and CD107a expression in response to leukemia cell line K562. When including biological sex as a variable in the analysis, transwell co-cultures of NK cells with either male- or female-derived PBMCs or pDCs stimulated with the TLR7/8 agonist CL097 showed that NK cells were more activated by CL097-stimulated cells derived from females. These sex-specific differences were linked to higher CL097-induced IFNα production by pDCs derived from females, indicating an extrinsic sex-specific effect of Type I IFNs on NK cell function. Interestingly, in addition to the extrinsic effect, we also observed NK cell-intrinsic sex differences, as female NK cells displayed higher activation levels after IFNα-stimulation and after co-culture with CL097-stimulated pDCs, suggesting higher activation of IFNα-signaling transduction in female NK cells. Taken together, the results from these studies identify both extrinsic and intrinsic sex-specific differences in Type I IFN-dependent NK cell functions, contributing to a better understanding of sex-specific differences in innate immunity.

Type I interferon subtypes differentially activate the anti-leukaemic function of natural killer cells

Natural killer (NK) cells have an intrinsic ability to detect and eliminate leukaemic cells. Cellular therapies using cytokine-activated NK cells have emerged as promising treatments for patients with advanced leukaemia. However, not all patients respond to current NK cell therapies, and thus improvements in efficacy are required. Type I interferons (IFN-I) are a family of potent immunomodulatory cytokines with a known ability to modulate NK cell responses against cancer. Although the human IFN-I family comprises 16 distinct subtypes, only IFNα2 has been widely explored as an anti-cancer agent. Here, we investigated the individual immunomodulatory effects each IFNα subtype and IFNβ had on NK cell functionality to determine whether a particular subtype confers enhanced effector activity against leukaemia. Importantly, IFNα14 and IFNβ were identified as superior activators of NK cell effector function in vitro. To test the ability of these subtypes to enhance NK cell activity in vivo, IFN-I stimulation was overlaid onto a standard ex vivo expansion protocol to generate NK cells for adoptive cell therapy. Interestingly, infusion of NK cells pre-activated with IFNα14, but not IFNβ, significantly prolonged survival in a preclinical model of leukaemia compared to NK cells expanded without IFN-I. Collectively, these results highlight the diverse immunomodulatory potencies of individual IFN-I subtypes and support further investigation into the use of IFNα14 to favourably modulate NK cells against leukaemia.

Synthetic mimetics assigned a major role to IFNAR2 in type I interferon signaling

Type I interferons (IFNs) are potent inhibitors of viral replication. Here, we reformatted the natural murine and human type I interferon-α/β receptors IFNAR1 and IFNAR2 into fully synthetic biological switches. The transmembrane and intracellular domains of natural IFNAR1 and IFNAR2 were conserved, whereas the extracellular domains were exchanged by nanobodies directed against the fluorescent proteins Green fluorescent protein (GFP) and mCherry. Using this approach, multimeric single-binding GFP-mCherry ligands induced synthetic IFNAR1/IFNAR2 receptor complexes and initiated STAT1/2 mediated signal transduction via Jak1 and Tyk2. Homodimeric GFP and mCherry ligands showed that IFNAR2 but not IFNAR1 homodimers were sufficient to induce STAT1/2 signaling. Transcriptome analysis revealed that synthetic murine type I IFN signaling was highly comparable to IFNα4 signaling. Moreover, replication of vesicular stomatitis virus (VSV) in a cell culture-based viral infection model using MC57 cells was significantly inhibited after stimulation with synthetic ligands. Using intracellular deletion variants and point mutations, Y510 and Y335 in murine IFNAR2 were verified as unique phosphorylation sites for STAT1/2 activation, whereas the other tyrosine residues in IFNAR1 and IFNAR2 were not involved in STAT1/2 phosphorylation. Comparative analysis of synthetic human IFNARs supports this finding. In summary, our data showed that synthetic type I IFN signal transduction is originating from IFNAR2 rather than IFNAR1.

Distinct Type I Interferon Subtypes Differentially Stimulate T Cell Responses in HIV-1-Infected Individuals

The expression of type I interferons (IFNs) is one of the immediate host responses during most viral infections. The type I IFN family consists of numerous highly conserved IFNα subtypes, IFNβ, and some others. Although these IFNα subtypes were initially believed to act interchangeably, their discrete biological properties are nowadays widely accepted. Subtype-specific antiviral, immunomodulatory, and anti-proliferative activities were reported explained by differences in receptor affinity, downstream signaling events, and individual IFN-stimulated gene expression patterns. Type I IFNs and increased IFN signatures potentially linked to hyperimmune activation of T cells are critically discussed for chronic HIV (human immunodeficiency virus) infection. Here, we aimed to analyze the broad immunological effects of specific type I IFN subtypes (IFNα2, IFNα14, and IFNβ) on T and NK cell subsets during HIV-1 infection in vitro and ex vivo. Stimulation with IFNα14 and IFNβ significantly increased frequencies of degranulating (CD107a⁺) gut-derived CD4⁺ T cells and blood-derived T and NK cells. However, frequencies of IFNγ-expressing T cells were strongly reduced after stimulation with IFNα14 and IFNβ. Phosphorylation of downstream molecules was not only IFN subtype-specific; also, significant differences in STAT5 phosphorylation were observed in both healthy peripheral blood mononuclear cells (PBMCs) and PBMCs of HIV-infected individuals, but this effect was less pronounced in healthy gut-derived lamina propria mononuclear cells (LPMCs), assuming cell and tissue specific discrepancies. In conclusion, we observed distinct type I IFN subtype-specific potencies in stimulating T and NK cell responses during HIV-1-infection.

Differential Inhibition of HIV Replication by the 12 Interferon Alpha Subtypes

Type I interferons (IFNs) are a family of cytokines that represent a first line of defense against virus infections. The 12 different IFN-α subtypes share a receptor on target cells and trigger similar signaling cascades. Several studies have collectively shown that this apparent redundancy conceals qualitatively different responses induced by individual subtypes, which display different efficacies of inhibition of HIV replication. Some studies, however, provided evidence that the disparities are quantitative rather than qualitative. Since RNA expression analyses show a large but incomplete overlap of the genes induced, they may support both models. To explore if the IFN-α subtypes induce functionally relevant different anti-HIV activities, we have compared the efficacies of inhibition of all 12 subtypes on HIV spread and on specific steps of the viral replication cycle, including viral entry, reverse transcription, protein synthesis, and virus release. Finding different hierarchies of inhibition would validate the induction of qualitatively different responses. We found that while most subtypes similarly inhibit virus entry, they display distinctive potencies on other early steps of HIV replication. In addition, only some subtypes were able to target effectively the late steps. The extent of induction of known anti-HIV factors helps to explain some, but not all differences observed, confirming the participation of additional IFN-induced anti-HIV effectors. Our findings support the notion that different IFN-α subtypes can induce the expression of qualitatively different antiviral activities. IMPORTANCE The initial response against viruses relies in large part on type I interferons, which include 12 subtypes of IFN-α. These cytokines bind to a common receptor on the cell surface and trigger the expression of incompletely overlapping sets of genes. Whether the anti-HIV responses induced by IFN-α subtypes differ in the extent of expression or in the nature of the genes involved remains debated. Also, RNA expression profiles led to opposite conclusions, depending on the importance attributed to the induction of common or distinctive genes. To explore if relevant anti-HIV activities can be differently induced by the IFN-α subtypes, we compared their relative efficacies on specific steps of the replication cycle. We show that the hierarchy of IFN potencies depends on the step analyzed, supporting qualitatively different responses. This work will also prompt the search for novel IFN-induced anti-HIV factors acting on specific steps of the replication cycle.

Structural integrity with functional plasticity: what type I IFN receptor polymorphisms reveal

The type I IFNs activate an array of signaling pathways, which are initiated after IFNs bind their cognate receptors, IFNα/β receptor (IFNAR)1 and IFNAR2. These signals contribute to many aspects of human health including defense against pathogens, cancer immunosurveillance, and regulation of inflammation. How these cytokines interact with their receptors influences the quality of these signals. As such, the integrity of receptor structure is pivotal to maintaining human health and the response to immune stimuli. This review brings together genome wide association studies and clinical reports describing the association of nonsynonymous IFNAR1 and IFNAR2 polymorphisms with clinical disease, including altered susceptibility to viral and bacterial pathogens, autoimmune diseases, cancer, and adverse reactions to live-attenuated vaccines. We describe the amino acid substitutions or truncations induced by these polymorphisms and, using the knowledge of IFNAR conformational changes, IFNAR-IFN interfaces and overall structure-function relationship of the signaling complexes, we hypothesize the effect of these polymorphisms on receptor structure. That these predicted changes to IFNAR structure are associated with clinical manifestations of human disease, highlights the importance of IFNAR structural integrity to maintaining functional quality of these receptor-mediated responses. Type I IFNs are pivotal to innate immune responses and ultimately, to human health. Understanding the consequences of altered structure on the actions of these clinically significant cell receptors provides important information on the roles of IFNARs in health and disease.

The Role of Cutaneous Type I IFNs in Autoimmune and Autoinflammatory Diseases

IFNs are well known as mediators of the antimicrobial response but also serve as important immunomodulatory cytokines in autoimmune and autoinflammatory diseases. An increasingly critical role for IFNs in evolution of skin inflammation in these patients has been recognized. IFNs are produced not only by infiltrating immune but also resident skin cells, with increased baseline IFN production priming for inflammatory cell activation, immune response amplification, and development of skin lesions. The IFN response differs by cell type and host factors and may be modified by other inflammatory pathway activation specific to individual diseases, leading to differing clinical phenotypes. Understanding the contribution of IFNs to skin and systemic disease pathogenesis is key to development of new therapeutics and improved patient outcomes. In this review, we summarize the immunomodulatory role of IFNs in skin, with a focus on type I, and provide insight into IFN dysregulation in autoimmune and autoinflammatory diseases.

Viral pathogen-induced mechanisms to antagonize mammalian interferon (IFN) signaling pathway

Antiviral responses of interferons (IFNs) are crucial in the host immune response, playing a relevant role in controlling viralw infections. Three types of IFNs, type I (IFN-α, IFN-β), II (IFN-γ) and III (IFN-λ), are classified according to their receptor usage, mode of induction, biological activity and amino acid sequence. Here, we provide a comprehensive review of type I IFN responses and different mechanisms that viruses employ to circumvent this response. In the first part, we will give an overview of the different induction and signaling cascades induced in the cell by IFN-I after virus encounter. Next, highlights of some of the mechanisms used by viruses to counteract the IFN induction will be described. And finally, we will address different mechanism used by viruses to interference with the IFN signaling cascade and the blockade of IFN induced antiviral activities.

Qualitative Differences Between the IFNα subtypes and IFNβ Influence Chronic Mucosal HIV-1 Pathogenesis

The Type I Interferons (IFN-Is) are innate antiviral cytokines that include 12 different IFNα subtypes and IFNβ that signal through the IFN-I receptor (IFNAR), inducing hundreds of IFN-stimulated genes (ISGs) that comprise the 'interferome'. Quantitative differences in IFNAR binding correlate with antiviral activity, but whether IFN-Is exhibit qualitative differences remains controversial. Moreover, the IFN-I response is protective during acute HIV-1 infection, but likely pathogenic during the chronic stages. To gain a deeper understanding of the IFN-I response, we compared the interferomes of IFNα subtypes dominantly-expressed in HIV-1-exposed plasmacytoid dendritic cells (1, 2, 5, 8 and 14) and IFNβ in the earliest cellular targets of HIV-1 infection. Primary gut CD4 T cells from 3 donors were treated for 18 hours ex vivo with individual IFN-Is normalized for IFNAR signaling strength. Of 1,969 IFN-regulated genes, 246 'core ISGs' were induced by all IFN-Is tested. However, many IFN-regulated genes were not shared between the IFNα subtypes despite similar induction of canonical antiviral ISGs such as ISG15, RSAD2 and MX1, formally demonstrating qualitative differences between the IFNα subtypes. Notably, IFNβ induced a broader interferome than the individual IFNα subtypes. Since IFNβ, and not IFNα, is upregulated during chronic HIV-1 infection in the gut, we compared core ISGs and IFNβ-specific ISGs from colon pinch biopsies of HIV-1-uninfected (n = 13) versus age- and gender-matched, antiretroviral-therapy naïve persons with HIV-1 (PWH; n = 19). Core ISGs linked to inflammation, T cell activation and immune exhaustion were elevated in PWH, positively correlated with plasma lipopolysaccharide (LPS) levels and gut IFNβ levels, and negatively correlated with gut CD4 T cell frequencies. In sharp contrast, IFNβ-specific ISGs linked to protein translation and anti-inflammatory responses were significantly downregulated in PWH, negatively correlated with gut IFNβ and LPS, and positively correlated with plasma IL6 and gut CD4 T cell frequencies. Our findings reveal qualitative differences in interferome induction by diverse IFN-Is and suggest potential mechanisms for how IFNβ may drive HIV-1 pathogenesis in the gut.

Plasmacytoid dendritic cells respond to Epstein-Barr virus infection with a distinct type I interferon subtype profile

Infectious mononucleosis, caused by infection with the human gamma-herpesvirus Epstein-Barr virus (EBV), manifests with one of the strongest CD8⁺ T-cell responses described in humans. The resulting T-cell memory response controls EBV infection asymptomatically in the vast majority of persistently infected individuals. Whether and how dendritic cells (DCs) contribute to the priming of this near-perfect immune control remains unclear. Here we show that of all the human DC subsets, plasmacytoid DCs (pDCs) play a central role in the detection of EBV infection in vitro and in mice with reconstituted human immune system components. pDCs respond to EBV by producing the interferon (IFN) subtypes α1, α2, α5, α7, α14, and α17. However, the virus curtails this type I IFN production with its latent EBV gene products EBNA3A and EBNA3C. The induced type I IFNs inhibit EBV entry and the proliferation of latently EBV-transformed B cells but do not influence lytic reactivation of the virus in vitro. In vivo, exogenous IFN-α14 and IFN-α17, as well as pDC expansion, delay EBV infection and the resulting CD8⁺ T-cell expansion, but pDC depletion does not significantly influence EBV infection. Thus, consistent with the observation that primary immunodeficiencies compromising type I IFN responses affect only alpha- and beta-herpesvirus infections, we found that EBV elicits pDC responses that transiently suppress viral replication and attenuate CD8⁺ T-cell expansion but are not required to control primary infection.

Diversity of locally produced IFN-α subtypes in human nasopharyngeal epithelial cells and mouse lung tissues during influenza virus infection

The excessively expressed interferon-α (IFN-α) might contribute to the uncontrolled inflammatory responses, causing pathological damage during influenza virus infection. However, the correlation of the pathological damage with the expression profile of IFN-α subtypes in the focus of infection with influenza viruses is poorly understood. To investigate this, we detected the IFN-α subtype dominance in human respiratory epithelial cells and mouse lungs, both of which were infected with influenza viruses. It was found that IFN-α1, IFN-α6, IFN-α14, and IFN-α16 were dominantly expressed in respiratory epithelial cells from the patients infected with IAV, whereas IFN-α5, IFN-α8, and IFN-α21 were dominantly expressed in respiratory epithelial cells from the patients infected with less pathogenic IBV and that IFN-α1, IFN-α9, and IFN-α15 were dominantly expressed in lungs of the mice infected with H1N1 IAV, and IFN-α2, IFN-α12, and IFN-α13 were dominantly expressed in lungs of the mice infected with less pathogenic H9N2 IAV. Compared with H9N2 IAV, H1N1 IAV induced higher mortality rates and more obvious body weight loss in the mice. In addition, IAV or H1N1 IAV induced a significantly higher level of CXCL10 mRNA in the human respiratory epithelial cells or the mouse lungs, respectively. In mice, the high level of Cxcl10 mRNA was accompanied by the abundant infiltrated neutrophils and more severe pathological changes in the lungs. Together, the data presented here indicate that the pathogenicity of influenza viruses is correlated with the IFN-α subtypes induced by influenza viruses. KEY POINTS: • Different influenza viruses induce differential inflammation responses. • Various influenza viruses induce diverse expression profiles of IFN-α subtypes. • The locally produced IFN-α subtypes correlated to the differential inflammation. Graphical abstract.

Diverse Anti-Tumor Immune Potential Driven by Individual IFNα Subtypes

Immunotherapies harnessing T cell immunity have shown remarkable clinical success for the management of cancer. However, only a proportion of patients benefit from these treatments. The presence of type I interferon (IFN) within the tumor microenvironment is critical for driving effective tumor-specific T cell immunity. Individuals can produce 12 distinct subtypes of IFNα, which all signal through a common receptor. Despite reported differences in anti-viral potencies, the concept that distinct IFNα subtypes can improve anti-cancer treatments remains unclear. We tested whether expression of unique IFNα subtypes confined to the tumor microenvironment enhances tumor control. This was systematically evaluated by transplantation of B16 murine melanoma cells secreting five unique IFNα subtypes (B16_IFNα2; B16_IFNα4; B16_IFNα5; B16_IFNα6; B16_IFNα9) into a pre-clinical murine model. We show that IFNα2 and IFNα9 are the only subtypes capable of completely controlling tumor outgrowth, with this protection dependent on the presence of an adaptive immune response. We next determined whether these differences extended to other model systems and found that the adoptive transfer of tumor-specific CD8⁺ T cells engineered to secrete IFNα9 delays tumor growth significantly and improves survival, whereas no enhanced survival was observed using T cells secreting IFNα4. Overall, our data shows that the expression of distinct IFNα subtypes within the tumor microenvironment results in different anti-tumor activities, and differentially affects the efficacy of a cancer therapy targeting established disease.

PD-L1/PD-1 Axis in Glioblastoma Multiforme

Glioblastoma (GBM) is the most popular primary central nervous system cancer and has an extremely expansive course. Aggressive tumor growth correlates with short median overall survival (OS) oscillating between 14 and 17 months. The survival rate of patients in a three-year follow up oscillates around 10%. The interaction of the proteins programmed death-1 (PD-1) and programmed cell death ligand (PD-L1) creates an immunoregulatory axis promoting invasion of glioblastoma multiforme cells in the brain tissue. The PD-1 pathway maintains immunological homeostasis and protects against autoimmunity. PD-L1 expression on glioblastoma surface promotes PD-1 receptor activation in microglia, resulting in the negative regulation of T cell responses. Glioblastoma multiforme cells induce PD-L1 secretion by activation of various receptors such as toll like receptor (TLR), epidermal growth factor receptor (EGFR), interferon alpha receptor (IFNAR), interferon-gamma receptor (IFNGR). Binding of the PD-1 ligand to the PD-1 receptor activates the protein tyrosine phosphatase SHP-2, which dephosphorylates Zap 70, and this inhibits T cell proliferation and downregulates lymphocyte cytotoxic activity. Relevant studies demonstrated that the expression of PD-L1 in glioma correlates with WHO grading and could be considered as a tumor biomarker. Studies in preclinical GBM mouse models confirmed the safety and efficiency of monoclonal antibodies targeting the PD-1/PD-L1 axis. Satisfactory results such as significant regression of tumor mass and longer animal survival time were observed. Monoclonal antibodies inhibiting PD-1 and PD-L1 are being tested in clinical trials concerning patients with recurrent glioblastoma multiforme.

Diverse Immunomodulatory Effects of Individual IFNα Subtypes on Virus-Specific CD8+ T Cell Responses

Clinical administration of Interferon α (IFNα) resulted in limited therapeutic success against some viral infections. Immune modulation of CD8+ T cell responses during IFNα therapy is believed to play a pivotal role in promoting viral clearance. However, these clinical studies primarily focused on IFNα subtype 2. To date, the immunomodulatory roles of the remaining 10-13 IFNα subtypes remains poorly understood, thereby precluding assessments of their potential for more effective treatments. Here, we report that virus-specific CD8+ T cell responses were influenced to various extents by individual IFNα subtypes. IFNα4, 6, and 9 had the strongest effects on CD8+ T cells, including antiproliferative effects, improved cytokine production and cytotoxicity. Interestingly, augmented cytokine responses were dependent on IFNα subtype stimulation of dendritic cells (DCs), while antiproliferative effects and cytotoxicity were mediated by IFNAR signaling in either CD8+ T cells or DCs. Thus, precise modulation of virus-specific CD8+ T cell responses may be feasible for specific antiviral immunotherapies through careful selection and administration of individual IFNα subtypes.

Dose-Dependent Differences in HIV Inhibition by Different Interferon Alpha Subtypes While Having Overall Similar Biologic Effects

Elucidating the functional role of the IFN-α subtypes is of particular importance for the development of efficacious therapies using exogenous IFN-α. Specifically, this will help define whether IFN therapy should be based on the use of pathogen-dependent IFN subtypes or, rather, IFN mutants with optimized IFNAR binding properties.

Type I interferons (IFNs) are key players in the antiviral immune response. Interferon alpha (IFN-α) belongs to this class of IFNs and comprises 12 subtypes that differ from each other in their binding affinities for a common receptor and, thus, in their signaling potencies. Recent data suggest that IFN-α6 and -α14 are the most potent IFN-α subtypes in restricting HIV replication when applied exogenously. However, in the context of antiviral therapy, IFNs are administered at high doses, which may compensate for differences in potency seen between IFN-α subtypes. In this study, we reexamined whether IFN-α subtypes induce different biological activities, with a focus on how IFN-α treatment dose affects cellular responses to HIV in primary CD4⁺ T cells, peripheral blood mononuclear cells (PBMCs), and macrophages. We found that the subtypes’ antiviral activities were dose dependent, with >90% inhibition of HIV replication at a high dose of all IFN-αs except the weak IFN-α/β receptor (IFNAR) binder, IFN-α1. The quality of the responses engendered by IFN-α1, -α2, -α6, and -α14 was highly comparable, with essentially the same set of genes induced by all four subtypes. Hierarchal cluster analysis revealed that the individual donors were stronger determinants for the IFN-stimulated-gene (ISG) responses than the specific IFN-α subtype used for stimulation. Notably, IFN-α2-derived mutants with substantially reduced IFNAR2 binding still inhibited HIV replication efficiently, whereas mutants with increased IFNAR1 binding potentiated antiviral activity. Overall, our results support the idea that IFN-α subtypes do not induce different biological responses, given that each subtype is exogenously applied at bioequivalent doses.

IMPORTANCE Elucidating the functional role of the IFN-α subtypes is of particular importance for the development of efficacious therapies using exogenous IFN-α. Specifically, this will help define whether IFN therapy should be based on the use of pathogen-dependent IFN subtypes or, rather, IFN mutants with optimized IFNAR binding properties.

Analysis of Four Types of Leukemia Using Gene Ontology Term and Kyoto Encyclopedia of Genes and Genomes Pathway Enrichment Scores

AIM AND OBJECTIVE

Leukemia is the second common blood cancer after lymphoma, and its incidence rate has an increasing trend in recent years. Leukemia can be classified into four types: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myelogenous leukemia (CML). More than forty drugs are applicable to different types of leukemia based on the discrepant pathogenesis. Therefore, the identification of specific drug-targeted biological processes and pathways is helpful to determinate the underlying pathogenesis among such four types of leukemia.

METHODS

In this study, the gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were highly related to drugs for leukemia were investigated for the first time. The enrichment scores for associated GO terms and KEGG pathways were calculated to evaluate the drugs and leukemia. The feature selection method, minimum redundancy maximum relevance (mRMR), was used to analyze and identify important GO terms and KEGG pathways.

RESULTS

Twenty Go terms and two KEGG pathways with high scores have all been confirmed to effectively distinguish four types of leukemia.

CONCLUSION

This analysis may provide a useful tool for the discrepant pathogenesis and drug design of different types of leukemia.

Interferon-alpha promotes immunosuppression through IFNAR1/STAT1 signalling in head and neck squamous cell carcinoma

BACKGROUND

An immunosuppressive microenvironment is critical for cancer initiation and progression. Whether interferon alpha (IFNα) can suppress immune and cancer cells and its involved mechanism still remain largely elusive.

METHODS

We examine the expression of interferon alpha/beta receptor-1 (IFNAR1), CD8, CD56 and programmed death ligand 1 (PDL1) in head and neck squamous cell carcinomas (HNSCC). The effect of IFNα on PDL1 and programmed cell death protein 1 (PD1) expression in tumour cells and immune cells was detected in vitro and in vivo.

RESULTS

Overexpression of IFNAR1, MX1 and signal transducer and activator of transcription 1 (Stat1) indicated the endogenous IFNα activation in tumour microenvironment, which correlated with immunosuppression status in HNSCC patients. Moreover, IFNα transcriptionally activated the expression of PDL1 through p-Stat1 (Tyr701) and promoted PD1 expression in immune cells through IFNAR1. The inhibition of IFNα signalling enhanced the cytotoxic activity of nature killer cells. At lastastly, we confirmed the upregulation of PDL1 and PD1 in response to IFNα treatment in both xenograft tumour models and patient-derived xenograft models.

CONCLUSIONS

Our findings demonstrate that IFNα-induced PDL1 and PD1 expression is a new mechanism of immunosuppression in HNSCC, suggesting that blocking IFNα signalling may enhance the efficacy of immune checkpoint blockade.

STIM1 and STIM2 Mediate Cancer-Induced Inflammation in T Cell Acute Lymphoblastic Leukemia

T cell acute lymphoblastic leukemia (T-ALL) is commonly associated with activating mutations in the NOTCH1 pathway. Recent reports have shown a link between NOTCH1 signaling and intracellular Ca2+ homeostasis in T-ALL. Here, we investigate the role of store-operated Ca2+ entry (SOCE) mediated by the Ca2+ channel ORAI1 and its activators STIM1 and STIM2 in T-ALL. Deletion of STIM1 and STIM2 in leukemic cells abolishes SOCE and significantly prolongs the survival of mice in a NOTCH1-dependent model of T-ALL. The survival advantage is unrelated to the leukemic cell burden but is associated with the SOCE-dependent ability of malignant T lymphoblasts to cause inflammation in leukemia-infiltrated organs. Mice with STIM1/STIM2-deficient T-ALL show a markedly reduced necroinflammatory response in leukemia-infiltrated organs and downregulation of signaling pathways previously linked to cancer-induced inflammation. Our study shows that leukemic T lymphoblasts cause inflammation of leukemia-infiltrated organs that is dependent on SOCE.

Expression Pattern of Individual IFNA Subtypes in Chronic HIV Infection

Interferon-α (IFN-α) plays an important role in HIV pathogenesis. IFN-α consists of 13 individual IFN-α subtypes, which exhibit individual antiviral and immunomodulatory activities in HIV infection. Here, we determined the expression profiles of all IFN-α subtypes in treated and treatment-naive HIV⁺ patients and their impact on the induction of distinct HIV restriction factors. We collected blood samples of chronic HIV⁺ patients, which underwent antiretroviral therapy or were treatment-naive, and determined the individual expression levels of different IFN-α subtypes and HIV restriction factors. HIV infection transiently enhanced the expression of IFNA mRNA. The IFN-α response was dominated by the most abundantly expressed subtypes IFNA4, A5, A7, and A14 in all individuals. HIV infection affected the expression pattern of the IFN-α response, in particular for IFNA2 and IFNA16, which were elevated by chronic HIV infection. Elevated expression of HIV restriction factors was observed in chronically HIV-infected patients, which partly decreased during successful antiretroviral treatment. In vitro stimulation of peripheral blood mononuclear cells revealed that IFN-α6, -α14, and -α21 were most effective in inducing the expression of HIV restriction factors. These results indicate that HIV infection induces a specific expression pattern of IFN-α subtypes, which in turn induce the expression of various HIV restriction factors.

IFNβ inhibits the development of allergen tolerance and is conducive to the development of asthma on subsequent allergen exposure

Asthma is a chronic disease affecting up to 10% of the Australian population for which medical treatment is solely aimed at relief of symptoms rather than prevention of disease. Evidence from animal and human studies demonstrates a strong link between viral respiratory infections, atopy and the development of asthma. Type I IFNs include IFNα and IFNβ, with subtype expression tailored toward the specific viral infection. We hypothesized that exposure to type I IFNs and allergen may interfere with the healthy response to innocuous airway antigen exposure. In this study, we use an ovalbumin (OVA)-induced BALB/c model of experimental allergic airways disease, where pre-exposure of the airways to OVA is protective against allergen sensitization, leading to allergen tolerance. We investigated airways pre-exposure with OVA and type I IFNs on development of allergic airways disease. We demonstrate restoration of allergic airways disease on pre-exposure with allergen and IFNβ, and not IFNα. Dysfunction in tolerance led to changes in dendritic cell antigen capture/traffic, T-cell and B-cell responses. Furthermore, exposure to IFNβ with ongoing allergen exposure led to the development of hallmark asthma features, including OVA-specific IgE and airways eosinophilia. Data indicate a role for IFNβ in linking viral infection and allergy.

Gene therapy with plasmids encoding IFN-β or IFN-α14 confers long-term resistance to HIV-1 in humanized mice

Because endogenous interferon type I (IFN-I) produced by HIV-1 infection might complicate the analysis of therapeutically administered IFN-I, we tested different humanized mouse models for induction of IFN-I during HIV-1 infection. While HIV-1 induced high levels of IFN-α in BLT mice, IFN-I was undetectable following infection in the Hu-PBL mouse model, in which only T cells expand. We therefore tested the effect of treatment with Pegylated IFN-2 (pegasys), in Hu-PBL mice. Pegasys prevented CD4 T cell depletion and reduced the viral load for 10 days, but the effect waned thereafter. We next expressed IFN-I subsets (IFN-α2, −α6, −α8, −α14, and −β) in Hu-PBL mice by hydrodynamic injection of plasmids encoding them and 2 days later infected the mice with HIV-1. CD4 T cell depletion was prevented in all subtypes of IFN-I-expressing mice by day 10. However, at day 40 post-infection, protection was seen in IFN-β- and IFN-α14-expressing mice, but not the others. The viral load followed an inverse pattern and was highest in control mice and lowest in IFN-β- and IFN-α14-expressing mice until day 40 after infection. These results show that gene therapy with plasmids encoding IFN-β and −α14, but not the commonly used −α2, confers long-term suppression of HIV-1 replication.

Interferon α subtypes in HIV infection

Type I interferons (IFN), which are immediately induced after most virus infections, are central for direct antiviral immunity and link innate and adaptive immune responses. However, several viruses have evolved strategies to evade the IFN response by preventing IFN induction or blocking IFN signaling pathways. Thus, therapeutic application of exogenous type I IFN or agonists inducing type I IFN responses are a considerable option for future immunotherapies against chronic viral infections. An important part of the type I IFN family are 12 IFNα subtypes, which all bind the same receptor, but significantly differ in their biological activities. Up to date only one IFNα subtype (IFNα2) is being used in clinical treatment against chronic virus infections, however its therapeutic success rate is rather limited, especially during Human Immunodeficiency Virus (HIV) infection. Recent studies addressed the important question if other IFNα subtypes would be more potent against retroviral infections in in vitro and in vivo experiments. Indeed, very potent IFNα subtypes were defined and their antiviral and immunomodulatory properties were characterized. In this review we summarize the recent findings on the role of individual IFNα subtypes during HIV and Simian Immunodeficiency Virus infection. This includes their induction during HIV/SIV infection, their antiretroviral activity and the regulation of immune response against HIV by different IFNα subtypes. The findings might facilitate novel strategies for HIV cure or functional cure studies.

Autocrine activation of the IFN signaling pathway may promote immune escape in glioblastoma

BACKGROUND

Interferons (IFNs) are cytokines typically induced upon viral infection but are constitutively expressed also in the absence of acute infection. The physiological role of autocrine and paracrine IFN signaling, however, remains poorly understood, and its function in glioblastoma has not been explored in depth.

METHODS

Using RNA interference-mediated gene silencing, we characterized constitutive type I IFN signaling and its role in human glioma cells.

RESULTS

We observed constitutive expression of phosphorylated signal transducer and activator of transcription 1 (pSTAT1) and myxovirus resistance protein A (MxA), a classical IFN-response marker, in the absence of exogenous IFN-β. In vivo, we found higher MxA expression in gliomas than in normal tissue, suggesting that IFN signaling is constitutively active in these tumors. To demonstrate the presence of an autocrine type I IFN signaling loop in glioma cells in vitro, we first confirmed the expression of the type I alpha/beta receptor (IFNAR)1/2, and its ligands, IFN-α and IFN-β. Small interfering RNA-mediated receptor gene silencing resulted in reduced expression of MxA at mRNA and protein levels, as did gene silencing of the ligands, corroborating the hypothesis of an autocrine signaling loop in which type I IFNs induce intracellular signaling through IFNAR1/2. On a functional level, following IFNAR1 or IFNAR2 gene silencing, we observed reduced programmed death ligand 1 (PD-L1) and major histocompatibility complex (MHC) class I and II expression as well as an enhanced susceptibility to natural killer immune cell lysis, suggesting that autocrine IFN signaling contributes to the immune evasion of glioma cells.

CONCLUSIONS

Our findings point to an important role of constitutive IFN signaling in glioma cells by modulating their interaction with the microenvironment.

Different antiviral effects of IFNα subtypes in a mouse model of HBV infection

Interferon alpha (IFNα) is commonly used for the treatment of chronic hepatitis B (CHB) patients. There are 13 different IFNα subtypes in humans, but only the subtype IFNα2 is used for clinical treatment. The antiviral activities of all other IFNα subtypes against HBV have not been studied. To obtain basic knowledge about the direct antiviral as well as the immunomodulatory effects of IFNα subtypes, we used the HBV hydrodynamic injection (HI) mouse model. Application of most IFNα subtype proteins inhibited HBV replication in vivo, with IFNα4 and IFNα5 being the most effective subtypes. Decreased viral loads after therapeutic application of IFNα4 and IFNα5 correlated with expanded effector cell populations of NK cells and T cells in both liver and spleen. Hydrodynamic injection of plasmids encoding for the effective IFNα subtypes (pIFNα) was even more potent against HBV than injecting IFNα proteins. The combination of pIFNα4 and pIFNα5 showed a synergistic antiviral effect on HBV replication, with a strong increase in NK cell and T cell activity. The results demonstrate distinct anti-HBV effects of different IFNα subtypes against HBV in the mouse model, which may be relevant for new therapeutic approaches.

Balance between IL-3 and type Iinterferons and their interrelationship with FasL dictates lifespan and effector functions of human basophils

BACKGROUND

In contrast to eosinophils and neutrophils, the regulation of the lifespan of human basophils is poorly defined, with the exception of the potent anti-apoptotic effect of IL-3 that also promotes pro-inflammatory effector functions and phenotypic changes. Type I IFNs (IFN-α, IFN-β), which are well known for their anti-viral activities, have the capacity to inhibit allergic inflammation.

OBJECTIVE

To elucidate whether type I IFNs have the potential to abrogate the lifespan and/or effector functions of human basophils.

METHODS

We cultured human basophils, and for comparison, eosinophils and neutrophils, with IL-3, interferons, FasL and TRAIL, alone or in combination, and studied cell survival, effector functions and signalling pathways involved.

RESULTS

Despite an identical pattern of early signalling in basophils, eosinophils and neutrophils in response to different types of interferons, only basophils displayed enhanced apoptosis after type I IFN treatment. IFN-γ prolonged survival of eosinophils but did not affect the lifespan of basophils. IFN-α-mediated apoptosis required STAT1-STAT2 heterodimers and the contribution of constitutive p38 MAPK activity. Whereas the death ligands FasL and TRAIL-induced apoptosis in basophils per se, IFN-α-mediated apoptosis did neither involve autocrine TRAIL signalling nor did it sensitize basophils to FasL-induced apoptosis. However, IFN-α and FasL displayed an additive effect in killing basophils. Interestingly, IL-3, which protected basophils from IFN-α-, TRAIL- or FasL-mediated apoptosis, did not completely block the additive effect of combined IFN-α and FasL treatment. Moreover, we demonstrate that IFN-α suppressed IL-3-induced release of IL-8 and IL-13. In contrast to IFN-α-mediated apoptosis, these inhibitory effects of IFN-α were not dependent on p38 MAPK signalling.

CONCLUSIONS AND CLINICAL RELEVANCE

Our study defines the unique and granulocyte-type-specific inhibitory and pro-apoptotic function of type I IFNs and their cooperation with death ligands in human blood basophils, which may be relevant for the anti-allergic properties of type I IFNs.

Different antiviral effects of IFNα and IFNβ in an HBV mouse model

Interferons α and β (IFNα and IFNβ) are type I interferons produced by the host to control pathogen propagation. However, only a minority of chronic hepatitis B (CHB) patients generate a sustained response after treatment with recombinant IFNα. The anti-HBV effect of IFNβ and the underlying mechanism are not well-understood. Here, we compared the antiviral activities of IFNα and IFNβ by application of IFNα or IFNβ expression plasmids using the well-established HBV hydrodynamic injection (HI) mouse model. Injection of IFNα expression plasmid could significantly reduce HBV serum markers including HBsAg, HBeAg and HBV DNA as well as the number of HBcAg positive cells in the liver, while IFNβ showed only a weak inhibition of HBV replication. In contrast to IFNβ, IFNα resulted in elevated expression levels of IFN stimulated genes (ISGs) as well as the proinflammatory cytokine interleukin 6 (IL6) in the liver. Moreover, IFNβ treated mice showed higher expression levels of the anti-inflammatory cytokines IL10 and TGFβ in the liver compared to IFNα. Our results demonstrated that both IFNα and IFNβ exert antiviral activities against HBV in HI mouse model, but IFNα is more effective than IFNβ.

Interferon Alpha Subtype-Specific Suppression of HIV-1 Infection In Vivo

Although all 12 subtypes of human interferon alpha (IFN-α) bind the same receptor, recent results have demonstrated that they elicit unique host responses and display distinct efficacies in the control of different viral infections. The IFN-α2 subtype is currently in HIV-1 clinical trials, but it has not consistently reduced viral loads in HIV-1 patients and is not the most effective subtype against HIV-1 in vitro We now demonstrate in humanized mice that, when delivered at the same high clinical dose, the human IFN-α14 subtype has very potent anti-HIV-1 activity whereas IFN-α2 does not. In both postexposure prophylaxis and treatment of acute infections, IFN-α14, but not IFN-α2, significantly suppressed HIV-1 replication and proviral loads. Furthermore, HIV-1-induced immune hyperactivation, which is a prognosticator of disease progression, was reduced by IFN-α14 but not IFN-α2. Whereas ineffective IFN-α2 therapy was associated with CD8(+) T cell activation, successful IFN-α14 therapy was associated with increased intrinsic and innate immunity, including significantly higher induction of tetherin and MX2, increased APOBEC3G signature mutations in HIV-1 proviral DNA, and higher frequencies of TRAIL(+) NK cells. These results identify IFN-α14 as a potent new therapeutic that operates via mechanisms distinct from those of antiretroviral drugs. The ability of IFN-α14 to reduce both viremia and proviral loads in vivo suggests that it has strong potential as a component of a cure strategy for HIV-1 infections. The broad implication of these results is that the antiviral efficacy of each individual IFN-α subtype should be evaluated against the specific virus being treated.

IMPORTANCE

The naturally occurring antiviral protein IFN-α2 is used to treat hepatitis viruses but has proven rather ineffective against HIV in comparison to triple therapy with the antiretroviral (ARV) drugs. Although ARVs suppress the replication of HIV, they fail to completely clear infections. Since IFN-α acts by different mechanism than ARVs and has been shown to reduce HIV proviral loads, clinical trials are under way to test whether IFN-α2 combined with ARVs might eradicate HIV-1 infections. IFN-α is actually a family of 12 distinct proteins, and each IFN-α subtype has different efficacies toward different viruses. Here, we use mice that contain a human immune system, so they can be infected with HIV. With this model, we demonstrate that while IFN-α2 is only weakly effective against HIV, IFN-α14 is extremely potent. This discovery identifies IFN-α14 as a more powerful IFN-α subtype for use in combination therapy trials aimed toward an HIV cure.

Type I interferonopathies in pediatric rheumatology

Defective regulation of type I interferon response is associated with severe inflammatory phenotypes and autoimmunity. Type I interferonopathies are a clinically heterogenic group of Mendelian diseases with a constitutive activation of this pathway that might present as atypical, severe, early onset rheumatic diseases. Skin vasculopathy with chilblains and livedo reticularis, interstitial lung disease, and panniculitis are common. Recent studies have implicated abnormal responses to nucleic acid stimuli or defective regulation of downstream effector molecules in disease pathogenesis. As observed for IL1-β and autoinflammatory diseases, knowledge of the defects responsible for type I interferonopathies will likely promote the development of targeted therapy.

Type I interferonopathies in pediatric rheumatology

Defective regulation of type I interferon response is associated with severe inflammatory phenotypes and autoimmunity. Type I interferonopathies are a clinically heterogenic group of Mendelian diseases with a constitutive activation of this pathway that might present as atypical, severe, early onset rheumatic diseases. Skin vasculopathy with chilblains and livedo reticularis, interstitial lung disease, and panniculitis are common. Recent studies have implicated abnormal responses to nucleic acid stimuli or defective regulation of downstream effector molecules in disease pathogenesis. As observed for IL1-β and autoinflammatory diseases, knowledge of the defects responsible for type I interferonopathies will likely promote the development of targeted therapy.

Interferon-α Subtypes in an Ex Vivo Model of Acute HIV-1 Infection: Expression, Potency and Effector Mechanisms

HIV-1 is transmitted primarily across mucosal surfaces and rapidly spreads within the intestinal mucosa during acute infection. The type I interferons (IFNs) likely serve as a first line of defense, but the relative expression and antiviral properties of the 12 IFNα subtypes against HIV-1 infection of mucosal tissues remain unknown. Here, we evaluated the expression of all IFNα subtypes in HIV-1-exposed plasmacytoid dendritic cells by next-generation sequencing. We then determined the relative antiviral potency of each IFNα subtype ex vivo using the human intestinal Lamina Propria Aggregate Culture model. IFNα subtype transcripts from the centromeric half of the IFNA gene complex were highly expressed in pDCs following HIV-1 exposure. There was an inverse relationship between IFNA subtype expression and potency. IFNα8, IFNα6 and IFNα14 were the most potent in restricting HIV-1 infection. IFNα2, the clinically-approved subtype, and IFNα1 were both highly expressed but exhibited relatively weak antiviral activity. The relative potencies correlated with binding affinity to the type I IFN receptor and the induction levels of HIV-1 restriction factors Mx2 and Tetherin/BST-2 but not APOBEC3G, F and D. However, despite the lack of APOBEC3 transcriptional induction, the higher relative potency of IFNα8 and IFNα14 correlated with stronger inhibition of virion infectivity, which is linked to deaminase-independent APOBEC3 restriction activity. By contrast, both potent (IFNα8) and weak (IFNα1) subtypes significantly induced HIV-1 GG-to-AG hypermutation. The results unravel non-redundant functions of the IFNα subtypes against HIV-1 infection, with strong implications for HIV-1 mucosal immunity, viral evolution and IFNα-based functional cure strategies.

Virus Multiplicity of Infection Affects Type I Interferon Subtype Induction Profiles and Interferon-Stimulated Genes

Type I interferons (IFNs) are induced upon viral infection and important mediators of innate immunity. While there is 1 beta interferon (IFN-β) protein, there are 12 different IFN-α subtypes. It has been reported extensively that different viruses induce distinct patterns of IFN subtypes, but it has not been previously shown how the viral multiplicity of infection (MOI) can affect IFN induction. In this study, we discovered the novel finding that human U937 cells infected with 2 different concentrations of Sendai virus (SeV) induce 2 distinct type I IFN subtype profiles. Cells infected at the lower MOI induced more subtypes than cells infected at the higher MOI. We found that this was due to the extent of signaling through the IFN receptor (IFNAR). The cells infected at the lower viral MOI induced the IFNAR2-dependent IFN-α subtypes 4, 6, 7, 10, and 17, which were not induced in cells infected at higher virus concentrations. IFN-β and IFN-α1, -2, and -8 were induced in an IFNAR-independent manner in cells infected at both virus concentrations. IFN-α5, -14, -16, and -21 were induced in an IFNAR-dependent manner in cells infected at lower virus concentrations and in an IFNAR-independent manner in cells infected at higher virus concentrations. These differences in IFN subtype profiles in the 2 virus concentrations also resulted in distinct interferon-stimulated gene induction. These results present the novel finding that different viral MOIs differentially activate JAK/STAT signaling through the IFNAR, which greatly affects the profile of IFN subtypes that are induced.

IMPORTANCE

Type I IFNs are pleiotropic cytokines that are instrumental in combating viral diseases. Understanding how the individual subtypes are induced is important in developing strategies to block viral replication. Many studies have reported that different viruses induce distinct type I IFN subtype profiles due to differences in the way viruses are sensed in different cell types. However, we report in our study the novel finding that the amount of virus used to infect a system can also affect which type I IFN subtypes are induced due to the extent of activation of certain signaling pathways. These distinct IFN subtype profiles in cells infected at different MOIs are correlated with differences in interferon-stimulated gene induction, indicating that the same virus can induce distinct antiviral responses depending on the MOI. Because type I IFNs are used as therapeutic agents to treat viral diseases, understanding their antiviral mechanisms can enhance clinical treatments.

Therapeutic potential of curcumin in digestive diseases

Curcumin is a low-molecular-weight hydrophobic polyphenol that is extracted from turmeric, which possesses a wide range of biological properties including anti-inflammatory, anti-oxidant, anti-proliferative and anti-microbial activities. Despite its diverse targets and substantial safety, clinical applications of this molecule for digestive disorders have been largely limited to case series or small clinical trials. The poor bioavailability of curcumin is likely the major hurdle for its more widespread use in humans. However, complexation of curcumin into phytosomes has recently helped to bypass this problem, as it has been demonstrated that this new lecithin formulation enables increased absorption to a level 29-fold higher than that of traditional curcuminoid products. This allows us to achieve much greater tissue substance delivery using significantly lower doses of curcumin than have been used in past clinical studies. As curcumin has already been shown to provide good therapeutic results in some small studies of both inflammatory and neoplastic bowel disorders, it is reasonable to anticipate an even greater efficacy with the advent of this new technology, which remarkably improves its bioavailability. These features are very promising and may represent a novel and effective therapeutic approach to both functional and organic digestive diseases.

IFN-α subtypes: distinct biological activities in anti-viral therapy

During most viral infections, the immediate host response is characterized by an induction of type I IFN. These cytokines have various biological activities, including anti-viral, anti-proliferative and immunomodulatory effects. After induction, they bind to their IFN-α/β receptor, which leads to downstream signalling resulting in the expression of numerous different IFN-stimulated genes. These genes encode anti-viral proteins that directly inhibit viral replication as well as modulate immune function. Thus, the induction of type I IFN is a very powerful tool for the host to fight virus infections. Many viruses evade this response by various strategies like the direct suppression of IFN induction or inhibition of the IFN signalling pathway. Therefore, the therapeutic application of exogenous type I IFN or molecules that induce strong IFN responses should be of great potential for future immunotherapies against viral infections. Type I IFN is currently used as a treatment in chronic hepatitis B and C virus infection, but as yet is not widely utilized for other viral infections. One reason for this restricted clinical use is that type I IFN belongs to a multigene family that includes 13 different IFN-α subtypes and IFN-β, whose individual anti-viral and immunomodulatory properties have so far not been investigated in detail to improve IFN therapy against viral infections in humans. In this review, we summarize the recent achievements in defining the distinct biological functions of type I IFN subtypes in cell culture and in animal models of viral infection as well as their clinical usage in chronic hepatitis virus infections.

Molecular mechanisms of curcumin action: signal transduction

Chemoprevention represents one of the most highly effective anti-cancer strategies and is accompanied by minimal secondary effects as compared to conventional chemotherapies. Many new anti-inflammatory and anti-cancer drug candidates have been derived from chemical scaffolds engineered from natural products discovered just a few decades ago. This approach is widely utilized in drug discovery in order to produce novel molecular entities with enhanced drug activities mediated through various signal transduction pathways for the treatment of different diseases. Curcumin, a polyphenolic derivative of turmeric, is a naturally occurring compound isolated from Curcuma longa that suppresses and inverts carcinogenesis via multifaceted molecular targets. Several reports have demonstrated that curcumin inhibits animal and human cancers, suggesting that it may serve as a chemopreventive agent. Numerous in vitro and in vivo experimental models have also revealed that curcumin regulates several molecules in cell signal transduction pathway including NF-κB, Akt, MAPK, p53, Nrf2, Notch-1, JAK/STAT, β-catenin, and AMPK. Modulation of cell signaling pathways through the pleiotropic effects of curcumin likely activate cell death signals and induce apoptosis in cancer cells, thereby inhibiting the progression of disease. This article provides insights into the natural chemopreventive role of curcumin via cellular transduction pathways and provides an in depth assessment of its physiological activities in the management of diseases.

Interferons as biomarkers and effectors: lessons learned from animal models

Interferons (IFNs) comprise type I, II and III families with multiple subtypes. Via transcription of IFN-stimulated genes (ISGs), IFNs can exert multiple biological effects on the cell. In infectious and chronic inflammatory diseases, the IFNs and their ISG sets can be potentially utilized as biomarkers of disease outcome. Animal models allow investigations into disease pathogenesis and gene knockout models have proved cause and effect relationships of molecules related to the IFN response. Sets of IFN subtypes and their ISG products provide immunological signature patterns for different viral and other diseases. In this article, we give an overview of IFNs in several virus infection models and autoimmune diseases of medical relevance. Lessons learned from animal models inform us of IFN system parameters as indicators of disease outcome and whether clinical research is warranted. Moreover, validated IFN biomarkers for prognosis enhance our understanding of therapeutic and vaccine development.

Interferon-alpha subtype 11 activates NK cells and enables control of retroviral infection

The innate immune response mediated by cells such as natural killer (NK) cells is critical for the rapid containment of virus replication and spread during acute infection. Here, we show that subtype 11 of the type I interferon (IFN) family greatly potentiates the antiviral activity of NK cells during retroviral infection. Treatment of mice with IFN-α11 during Friend retrovirus infection (FV) significantly reduced viral loads and resulted in long-term protection from virus-induced leukemia. The effect of IFN-α11 on NK cells was direct and signaled through the type I IFN receptor. Furthermore, IFN-α11-mediated activation of NK cells enabled cytolytic killing of FV-infected target cells via the exocytosis pathway. Depletion and adoptive transfer experiments illustrated that NK cells played a major role in successful IFN-α11 therapy. Additional experiments with Mouse Cytomegalovirus infections demonstrated that the therapeutic effect of IFN-α11 is not restricted to retroviruses. The type I IFN subtypes 2 and 5, which bind the same receptor as IFN-α11, did not elicit similar antiviral effects. These results demonstrate a unique and subtype-specific activation of NK cells by IFN-α11.

The innate immune response mediated by cells such as natural killer (NK) cells can contribute to immunity against viral infections. NK cells can kill virus-infected cells and thus inhibit virus replication and spread during acute infection. However, in infections with retroviruses, like HIV, these cells are not sufficient to prevent pathology. Here, we describe a new strategy to augment natural killer cell responses during virus infections by using a subtype of the type I interferon family as antiviral drug. This therapy strongly activated NK cells and enabled them to control retrovirus as well as herpes virus infections in mice. The new approach might have great potential for the treatment of many infectious and tumor diseases in which natural killer cells play a significant role in immunity.

The differential activity of interferon-α subtypes is consistent among distinct target genes and cell types

IFN-α proteins have been described to originate from 14 individual genes and allelic variants. However, the exceptional diversity of IFN-α and its functional impact are still poorly understood. To characterize the biological activity of IFN-α subtypes in relation to the cellular background, we investigated the effect of IFN-α treatment in primary fibroblasts and endothelial cells of vascular or lymphatic origin. The cellular response was evaluated for 13 distinct IFN-α proteins with respect to transcript regulation of the IFN-stimulated genes (ISGs) IFIT1, ISG15, CXCL10, CXCL11 and CCL8. The IFN-α proteins displayed a remarkably consistent potency in gene induction irrespective of target gene and cellular background which led to the classification of IFN-α subtypes with low (IFN-α1), intermediate (IFN-α2a, -4a, -4b, -5, -16, -21) and high (IFN-α2b, -6, -7, -8, -10, -14) activity. The differential potency of IFN-α classes was confirmed at the ISG protein level and the functional protection of cells against influenza virus infection. Differences in IFN activity were only observed at subsaturating levels of IFN-α proteins and did not affect the time course of ISG regulation. Cell-type specific responses were apparent for distinct target genes independent of IFN-α subtype and were based on different levels of basal versus inducible gene expression. While fibroblasts presented with a high constitutive level of IFIT1, the expression in endothelial cells was strongly induced by IFN-α. In contrast, CXCL10 and CXCL11 transcript levels were generally higher in endothelial cells despite a pronounced induction by IFN-α in fibroblasts. In summary, the divergent potency of IFN-α proteins and the cell-type specific regulation of individual IFN target genes may allow for the fine tuning of cellular responses to pathogen defense.

A functional and regulatory network associated with PIP expression in human breast cancer

BACKGROUND

The PIP (prolactin-inducible protein) gene has been shown to be expressed in breast cancers, with contradictory results concerning its implication. As both the physiological role and the molecular pathways in which PIP is involved are poorly understood, we conducted combined gene expression profiling and network analysis studies on selected breast cancer cell lines presenting distinct PIP expression levels and hormonal receptor status, to explore the functional and regulatory network of PIP co-modulated genes.

PRINCIPAL FINDINGS

Microarray analysis allowed identification of genes co-modulated with PIP independently of modulations resulting from hormonal treatment or cell line heterogeneity. Relevant clusters of genes that can discriminate between [PIP+] and [PIP-] cells were identified. Functional and regulatory network analyses based on a knowledge database revealed a master network of PIP co-modulated genes, including many interconnecting oncogenes and tumor suppressor genes, half of which were detected as differentially expressed through high-precision measurements. The network identified appears associated with an inhibition of proliferation coupled with an increase of apoptosis and an enhancement of cell adhesion in breast cancer cell lines, and contains many genes with a STAT5 regulatory motif in their promoters.

CONCLUSIONS

Our global exploratory approach identified biological pathways modulated along with PIP expression, providing further support for its good prognostic value of disease-free survival in breast cancer. Moreover, our data pointed to the importance of a regulatory subnetwork associated with PIP expression in which STAT5 appears as a potential transcriptional regulator.

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.

Anti-retroviral effects of type I IFN subtypes in vivo

Type I IFN play a very important role in immunity against viral infections. Murine type I IFN belongs to a multigene family including 14 IFN-alpha subtypes but the biological functions of IFN-alpha subtypes in retroviral infections are unknown. We have used the Friend retrovirus model to determine the anti-viral effects of IFN-alpha subtypes in vitro and in vivo. IFN-alpha subtypes alpha1, alpha4, alpha6 or alpha9 suppressed Friend virus (FV) replication in vitro, but differed greatly in their anti-viral efficacy in vivo. Treatment of FV-infected mice with the IFN-alpha subtypes alpha1, alpha4 or alpha9, but not alpha6 led to a significant reduction in viral loads. Decreased splenic viral load after IFN-alpha1 treatment correlated with an expansion of activated FV-specific CD8(+) T cells and NK cells into the spleen, whereas in IFN-alpha4- and -alpha9-treated mice it exclusively correlated with the activation of NK cells. The results demonstrate the distinct anti-retroviral effects of different IFN-alpha subtypes, which may be relevant for new therapeutic approaches.

Adenovirus induction of IRF3 occurs through a binary trigger targeting Jun N-terminal kinase and TBK1 kinase cascades and type I interferon autocrine signaling

Pathogen recognition is a critical function of immune sentinel cells. Naïve macrophages or dendritic cells (DCs) undergo pathogen-directed activation and maturation, and as mature antigen-presenting cells (APCs), they contribute essential functions to both innate and adaptive immunity. Using recombinant adenovirus (rAdV) as a model for murine APC activation by DNA viruses, we demonstrate a critical role for stress kinase activation in cell intrinsic and extrinsic antiviral signaling cascades. We propose two viral triggers, viral capsid and viral DNA, are required for APC activation. Endosomal escape and presentation of cytosolic rAdV DNA induces phosphorylation of TANK-binding kinase 1 (TBK1) at serine 172 but does not induce IkappaB kinase epsilon activity as determined by in vitro kinase assays. However, induction of TBK1 alone is not sufficient for interferon regulatory factor 3 (IRF3) phosphorylation. We show that capsid-dependent activation of Jun N-terminal kinase (JNK) stress kinase is a necessary step, licensing TBK1 phosphorylation of IRF3 at Ser 396. A second later phase of JNK activity is required to coordinate phosphorylation of JNK-dependent transcription factors (c-Jun/ATF2) with activated IRF3 in the induction of primary IRF3-responsive transcripts. Finally, we demonstrate that maximal JNK/TBK1/IRF3 stimulation by rAdV depends on an intact type I interferon (IFN) signaling cascade. By requiring multiple viral triggers and type I IFN autocrine regulation, APCs have an inherent fail-safe mechanism against inappropriate activation and maturation.

Molecular characterization of woodchuck type I interferons and their expression by woodchuck peripheral blood lymphocytes

Interferon (IFN)-alpha and -beta are important antiviral mediators. IFN-alpha is widely used for the treatment of chronic hepatitis B. In our previous studies, a subtype of woodchuck IFN-alpha (wIFN-alpha) was characterized and has been shown to be active in suppressing the replication of woodchuck hepatitis virus (WHV) in vitro and vivo. Here, we refined the analysis of the IFN-alpha/beta system of the woodchuck and studied the expression of wIFN-alpha/beta in peripheral blood lymphocytes (PBLs) from naïve and WHV-infected woodchucks. A number of wIFN-alpha genes were sequenced and could be classified into 10 subtypes and 3 pseudotypes. The biological activity of different subtypes of wIFN-alpha was demonstrated by their ability to protect woodchuck cells against encephalomyocarditis virus infection and to induce MxA expression in woodchuck cells. Additionally, a partial sequence of wIFN-beta was characterized. A subtyping method for wIFN-alpha based on restriction length polymorphism analysis was developed. Further, the expression of wIFN by woodchuck PBLs after stimulation with polyI/C was investigated. The maximal production of wIFN by woodchuck PBLs occurred within the first 48 h after addition poly I/C. The wIFN-alpha subtypes 1, 4, and 5 were found to be produced by poly I/C-stimulated woodchuck PBLs, indicating a selective expression of wIFN-alpha subtypes. PBLs from chronically WHV-infected woodchucks showed a reduced ability to produce wIFN when stimulated with poly I/C. The results suggest that woodchucks with chronic WHV infection have impaired immunological responses to poly I/C.

Differential activities of alpha/beta IFN subtypes against influenza virus in vivo and enhancement of specific immune responses in DNA vaccinated mice expressing haemagglutinin and nucleoprotein

Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccines can elicit partial protective immunity, however their efficacy requires improvement. We assessed the capacity of individual type I IFN multigene family members as subtype transgenes to abrogate influenza virus replication in a vaccination/challenge mouse model. Differences in antiviral efficacy were found among the subtypes with IFNA5 and IFNA6 being most effective, while IFNA1 was the least effective in reducing lung virus replication. Mice vaccinated with combinatorial HA/IFNA6 or NP/IFNA6 showed reduced lung viral titres, clinical score, body weight loss, and pulmonary tissue damage compared to IFNA6, HA, or NP viral vaccination alone. In addition, IFNA6 increased IgG2a titres with upregulation of IFN-gamma response in the respiratory tract. We conclude that IFN-alpha 6 has antiviral and immunomodulatory effects, which improve efficacy of DNA vaccines for enhanced control of influenza.

Complex Modulation of Cell Type-Specific Signaling in Response to Type I Interferons

The type I interferons (IFNs) are pleiotropic cytokines that regulate many different cellular functions. The major signaling pathway activated by type I IFNs involves sequential phosphorylation of the tyrosine residues of the Janus kinase (JAK) and signal transducers and activators of transcription (STAT) proteins, providing the primary mechanism through which gene expression is induced. Recent work has shown that the responses are quite complex, as shown by different responses to specific subtypes of type I IFN, activation of kinases in addition to JAKs, patterns of activation of all seven STATs in different cells, and activation of transcription factors other than STATs. The type I IFNs use this complexity to regulate many different biological functions in different types of cells, by activating different specific signals and patterns of gene expression.