Analysis of the antiviral activities of natural IFN-alpha preparations and their subtype compositions

Human Alveolar and Monocyte-Derived Human Macrophage Responses to Mycobacterium tuberculosis

Alveolar macrophages (AMs) and recruited monocyte-derived macrophages (MDMs) mediate early lung immune responses to Mycobacterium tuberculosis. Differences in the response of these distinct cell types are poorly understood and may provide insight into mechanisms of tuberculosis pathogenesis. The objective of this study was to determine whether M. tuberculosis induces unique and essential antimicrobial pathways in human AMs compared with MDMs. Using paired human AMs and 5-d MCSF-derived MDMs from six healthy volunteers, we infected cells with M. tuberculosis H37Rv for 6 h, isolated RNA, and analyzed transcriptomic profiles with RNA sequencing. We found 681 genes that were M. tuberculosis dependent in AMs compared with MDMs and 4538 that were M. tuberculosis dependent in MDMs, but not AMs (false discovery rate [FDR] < 0.05). Using hypergeometric enrichment of DEGs in Broad Hallmark gene sets, we found that type I and II IFN Response were the only gene sets selectively induced in M. tuberculosis-infected AM (FDR < 0.05). In contrast, MYC targets, unfolded protein response and MTORC1 signaling, were selectively enriched in MDMs (FDR < 0.05). IFNA1, IFNA8, IFNE, and IFNL1 were specifically and highly upregulated in AMs compared with MDMs at baseline and/or after M. tuberculosis infection. IFNA8 modulated M. tuberculosis-induced proinflammatory cytokines and, compared with other IFNs, stimulated unique transcriptomes. Several DNA sensors and IFN regulatory factors had higher expression at baseline and/or after M. tuberculosis infection in AMs compared with MDMs. These findings demonstrate that M. tuberculosis infection induced unique transcriptional responses in human AMs compared with MDMs, including upregulation of the IFN response pathway and specific DNA sensors.

Interferon-α Subtypes As an Adjunct Therapeutic Approach for Human Immunodeficiency Virus Functional Cure

Human immunodeficiency virus (HIV) establishes life-long latency in infected individuals. Although highly active antiretroviral therapy (HAART) has had a significant impact on the course of HIV infection leading to a better long-term outcome, the pool of latent reservoir remains substantial even under HAART. Numerous approaches have been under development with the goal of eradicating the latent HIV reservoir though with limited success. Approaches that combine immune-mediated control of HIV to activate both the innate and the adaptive immune system under suppressive therapy along with "shock and kill" drugs may lead to a better control of the reactivated virus. Interferon-α (IFN-α) is an innate cytokine that has been shown to activate intracellular defenses capable of restricting and controlling HIV. IFN-α, however, harbors numerous functional subtypes that have been reported to display different binding affinities and potency. Recent studies have suggested that certain subtypes such as IFN-α8 and IFN-α14 have potent anti-HIV activity with little or no immune activation, whereas other subtypes such as IFN-α4, IFN-α5, and IFN-α14 activate NK cells. Could these subtypes be used in combination with other strategies to reduce the latent viral reservoir? Here, we review the role of IFN-α subtypes in HIV infection and discuss the possibility that certain subtypes could be potential adjuncts to a "shock and kill" or therapeutic vaccination strategy leading to better control of the latent reservoir and subsequent functional cure.

Early treatment with reverse transcriptase inhibitors significantly suppresses peak plasma IFNα in vivo during acute simian immunodeficiency virus infection

Innate interferons (IFN) are comprised of multiple Type I and III subtypes. The in vivo kinetics of subtype responses during human immunodeficiency virus (HIV) infection is not well defined. Using the acute simian immunodeficiency virus (SIV) infection model, we show that plasma IFNα levels peak at day 10 post-infection (pi) after which they rapidly declined. The mRNA expression of Type I and III IFN subtypes were significantly elevated in the lymph nodes (LN) at day 10 pi. Though the expression levels of all subtypes declined by day 14-31 pi, numerous subtypes remained elevated suggesting that ongoing viral replication in LN continues to drive induction of these subtypes. Interestingly, treatment with reverse transcriptase (RT) inhibitors at day 7 pi significantly suppressed plasma IFNα responses by day 10 pi that significantly correlated with cell-associated SIV DNA loads suggesting that RT byproducts such as viral DNA likely plays a role in driving IFN responses during acute SIV infection. Quantification of Type I and III subtype transcripts in sorted subsets of LN CD4+ and CD8+ T cells, CD14+/CD14- monocytes/macrophages, and total CD11c/CD123+ dendritic cells (DC) at day 10 pi showed that DC expressed ∼3-4 log more subtype transcripts as compared to the other subsets. Taken together, our results provide new insights into the kinetics of innate interferon responses during early stages of infection, and provide evidence that DC's are a major in vivo source of innate IFN during acute SIV infection.

The type I interferons: Basic concepts and clinical relevance in immune-mediated inflammatory diseases

There is increasing scientific and clinical interest in elucidating the biology of type I Interferons, which began approximately 60 years ago with the concept of "viral interference", a property that reduces the ability of a virus to infect cells. Although our understanding of the multiple cellular and molecular functions of interferons has advanced significantly, much remains to be learned and type I Interferons remain an active and fascinating area of inquiry. In this review, we cover some general aspects of type I interferon genes, with emphasis on interferon-alpha, and various aspects of molecular mechanisms triggered by type I interferons and toll-like receptor signaling by the Janus activated kinase/signal transducer activation of transcription (JAK-STAT) pathway and interferon regulatory factor pathway. We will also describe the role of type I interferons in autoimmune and inflammatory diseases, and its potential use as therapeutic agent.

Interferon and the treatment of polycythemia vera, essential thrombocythemia and myelofibrosis

Recombinant IFN-α (rIFN-α) induces complete hematologic remissions in patients with myeloproliferative neoplasms (MPNs), but its use has been limited by side effects owing to the relatively high doses used. Now, low-dose rIFN-α is stressed, starting relatively early in the course of the MPNs. In polycythemia vera, this has resulted in a significant clinical, hematologic, morphologic and molecular response manifested by reduction in the JAK2(V617F) allele burden, sustained even after discontinuation of recombinant IFN. In essential thrombocythemia, platelet count reduction is prompt and durable without treatment for varying periods. In hypercellular primary myelofibrosis, rIFN-α has restored normal blood counts, reduced splenomegaly and induced morphologic marrow remissions. This article highlights our current use of rIFN-α in MPNs.

Expression profiles of human interferon-alpha and interferon-lambda subtypes are ligand- and cell-dependent

Recent genome-wide association studies suggest distinct roles for 12 human interferon-alpha (IFN-α) and 3 IFN-λ subtypes that may be elucidated by defining the expression patterns of these sets of genes. To overcome the impediment of high homology among each of the sets, we designed a quantitative real-time PCR assay that incorporates the use of molecular beacon and locked nucleic acid (LNA) probes, and in some instances, LNA oligonucleotide inhibitors. We then measured IFN subtype expression by human peripheral blood mononuclear cells and by purified monocytes, myeloid dendritic cells (mDC), plasmacytoid dendritic cells (pDC), and monocyte-derived macrophages (MDM), and -dendritic cells (MDDC) in response to poly I:C, lipopolysaccharide (LPS), imiquimod and CpG oligonucleotides. We found that in response to poly I:C and LPS, monocytes, MDM and MDDC express a subtype pattern restricted primarily to IFN-β and IFN-λ1. In addition, while CpG elicited expression of all type I IFN subtypes by pDC, imiquimod did not. Furthermore, MDM and mDC highly express IFN-λ, and the subtypes of IFN-λ are expressed hierarchically in the order IFN-λ1 followed by IFN-λ2, and then IFN-λ3. These data support a model of coordinated cell- and ligand-specific expression of types I and III IFN. Defining IFN subtype expression profiles in a variety of contexts may elucidate specific roles for IFN subtypes as protective, therapeutic or pathogenic mediators.

High-throughput quantitative real-time polymerase chain reaction array for absolute and relative quantification of rhesus macaque types I, II, and III interferon and their subtypes

Rhesus macaques provide a valuable research and preclinical model for cancer and infectious diseases, as nonhuman primates share immune pathways with humans. Interferons (IFNs) are key cytokines in both innate and adaptive immunity, so a detailed analysis of gene expression in peripheral blood and tissues may shed insight into immune responses. Macaques have 18 IFN genes, of which 14 encode for 13 distinct IFN-α subtypes, and one for IFN-β. Here, we developed a high-throughput array to evaluate each of the IFN-α subtypes, as well as IFN-β, IFN-γ and 2 subtypes of IFN-λ. With this array, expression of each IFN species may be quantified as relative to a reference (housekeeping) gene (ΔCq) or fitted to its own 4-point standard curve for absolute quantification (copy number per mass unit RNA). After validating the assay with IFN complementary DNA, we determined the IFN expression profile of peripheral blood mononuclear cells from 3 rhesus macaques in response to TLR agonists, and demonstrated that the profiles are consistent among animals. Furthermore, because the IFN expression profiles differ depending on the TLR stimuli, they suggest different biological functions for many of the IFN species measured, including individual subtypes of IFN-α.

Creation of interferon-alpha8 mutants with amino acid substitutions against interferon-alpha receptor-2 binding sites using phage display system and evaluation of their biologic properties

In this study, we describe the creation of three interferon-alpha (IFN-alpha)8 mutants with markedly higher antiviral and antiproliferative activities in comparison with those of the wild-type (wt)IFN-alpha8, wtIFN-alpha2, and IFN-con1 using a phage display system. Sequence analysis showed that three out of the six hot-spot amino acid residues of wtIFN-alpha8 known to be important for the interaction with the IFN-alpha receptor-2 (IFNAR-2)-binding sites were substituted to other amino acids and the others remained. Although affinity analysis revealed that the dissociation constant (K(D)) of IFN-alpha8 mutants was almost the same with that of wtIFN-alpha8, furthermore, the rates of association (k(a)) and dissociation (k(d)) were relatively lower. These results suggest that changes in the surface electronic charge of amino acid residues lead to changes in binding affinity and kinetics (prolonged dissociation time) toward the IFNAR-2, resulting in the modification of the biological activity. Moreover, our results demonstrate that the molecular engineering of the IFN-alpha8 provides important insight into action of IFN and also it would be useful in the development of therapeutically prominent IFN preparations than those used in clinical practice.

Applications of the Restriction Free (RF) cloning procedure for molecular manipulations and protein expression

Molecular manipulations, including DNA cloning and mutagenesis are basic tools used on a routine basis in all life-science disciplines. Over the last decade new methodologies have emerged that facilitated and expanded the applications for DNA cloning and mutagenesis. Ligation-Independent Cloning (LIC) techniques were developed and replaced the classical Ligation Dependent Cloning (LDC) platform. Restriction Free (RF) cloning was originally developed for introduction of foreign DNA into a plasmid at any predetermined position. RF cloning is based on PCR amplification of a DNA fragment, which serves as a mega-primer for the linear amplification of the vector and insert. Here we present several novel applications of the Restriction Free (RF) cloning platform for DNA cloning and mutagenesis. The new applications include simultaneous cloning of several DNA fragments into distinct positions within an expression vector, simultaneous multi-component assembly, and parallel cloning of the same PCR product into a series of different vectors. In addition, we have expanded the application of the RF cloning platform for multiple alterations of the target DNA, including simultaneous multiple-site mutagenesis and simultaneous introduction of deletions and insertions at different positions. We further demonstrate the robustness of the new applications for facilitating recombinant protein expression in the Escherichia coli system.

Rigid interferon-alpha subtype responses of human plasmacytoid dendritic cells

The large family of human type I interferon (IFN) includes 13 distinct subtypes of IFN-alpha, all utilizing a single type I IFN receptor. Many viruses have created evasion strategies to disable this cytokine family, highlighting their importance in antiviral defense. It is unclear what advantage the presence of so many different IFN-alpha subtypes provides, but functional differences observed among individual IFN-alpha subtypes suggested that they might play distinct regulatory roles during an immune response. To determine whether IFN-alpha subtype responses differ depending on a particular type of insult and thus whether IFN-alpha subtype responses are flexible to adapt to distinct pathogen challenges, we developed a novel nested multiplex reverse transcriptase polymerase chain reaction assay with which we measured expression of all IFN-alpha subtypes by freshly isolated human plasmacytoid dendritic cells (pDCs), a main source of IFN-alpha following pathogen challenge. Collectively our data show a remarkable stability in the relative magnitude and the kinetics of induction for each IFN-alpha subtype produced by pDC. Although various stimuli used, A-, B- and C-class CpGs, live and heat-inactivated influenza viruses and the TLR7 agonist R837 affected the overall magnitude of the response, each IFN-alpha subtype was induced at statistically similar relative levels and with similar kinetics, thereby revealing a great degree of rigidity in the IFN-alpha response pattern of pDC. These data are most consistent with the induction of optimized ratios of IFN-alpha subtypes, each of which may have differing signaling properties or alternatively, a great degree of redundancy in the IFN-alpha response.

Antitumor effects of a combination of interferon-alpha and sorafenib on human renal carcinoma cell lines

To support the role of interferon (IFN)-alpha and sorafenib combination therapy against renal cell carcinoma (RCC), the effects of IFN-alpha and sorafenib on tumor growth, vascular endothelial growth factor (VEGF) production, and phosphorylation levels of extracellular signal-regulated kinase (ERK) and mitogen-activated protein/ERK kinase (MEK) were examined using several cultured RCC cell lines (ACHN, Caki-1, Caki-2, SMKT-R1, SMKT-R2, SMKT-R3 and SMKT-R4). IFN-alpha or sorafenib alone inhibited the proliferation of all the cell lines except Caki-2, while combined treatment with the two agents showed enhanced inhibitory effects compared to treatment with each agent alone. VEGF production was inhibited by IFN-alpha alone in ACHN and SMKT-R2 cells and by sorafenib alone in ACHN, Caki-1, SMKT-R1 and SMKT-R2 cells. However, sorafenib increased VEGF production by Caki-2 cells. Interestingly, combined treatment with the two agents suppressed VEGF production by SMKT-R1 and SMKT-R2 cells more strongly than IFN-alpha or sorafenib alone. Although phosphorylated ERK (p-ERK) was increased after 30 min of treatment with IFN-alpha alone, no difference was observed between control and IFN-alpha-treated cells after 2 h. Sorafenib decreased p-ERK in ACHN, Caki-1, SMKT-R1 and SMKT-R2 cells, but increased p-ERK in Caki-2, SMKT-R3 and SMKT-R4 cells, after 2 h. Combined treatment with IFN-alpha and sorafenib decreased p-ERK compared to treatment with each agent alone in all cell lines except Caki-2. However, IFN-alpha did not inhibit the p-ERK increase induced by sorafenib in Caki-2 cells. Phosphorylated MEK showed similar patterns to p-ERK after the various treatments. In conclusion, combined treatment with IFN-alpha and sorafenib suppressed cell proliferation and VEGF production more strongly than treatment with each agent alone in several RCC cell lines.

Pretreatment with feline interferon omega and the course of subsequent infection with feline herpesvirus in cats

OBJECTIVE

Recombinant feline interferon omega (rFeIFN-omega), a type I IFN, may have the potential to limit virus replication and associated clinical signs when administered early on in the course of feline herpesvirus type 1 (FHV-1) infection and reactivation, respectively. The effect of rFeIFN-omega pretreatment on the course of subsequent FHV-1 infection in cats was investigated.

ANIMALS STUDIED

Nine SPF cats were divided into an IFN group (n = 5) and a control-group (n = 4).

PROCEDURES

The IFN group was pretreated for 2 days with 10 000 units rFeIFN-omega twice a day topically into both eyes and 20 000 units rFeIFN-omega once a day orally, whereas the control group was mock-treated. Subsequently all cats were infected with FHV-1. Samples for FHV-1 DNA detection and quantitation, virus isolation, and titration of FHV-1 antibodies were collected. Clinical and ocular signs were recorded and scored.

RESULTS

Courses of median individual clinical and ocular scores and virus load did not differ significantly between both groups using anova for repeated measurements. Analysis (anova) of each individual ocular parameter revealed significantly high scores for epithelial keratitis (P = 0.016) in the IFN group compared to the control group. Periods of virus shedding did not differ significantly between both groups using the Wilcoxon rank sum test.

CONCLUSIONS

Results indicated a lack of beneficial effects of rFeIFN-omega pretreatment in the course of primary FHV-1 infection in cats.

The combination of IFN-alpha2 and IFN-alpha8 exhibits synergistic antiproliferative activity on renal cell carcinoma (RCC) cell lines through increased binding affinity for IFNAR-2

Although there are at least 13 interferon-alpha (IFN-alpha) subtypes in humans, interactions between the subtypes remain unknown. To understand IFN-alpha interactions, we examined the antiproliferative activities and the receptor binding affinities of different combinations of IFN-alpha2 and IFN-alpha8 using six renal cell carcinoma (RCC) cell lines. Although IFN-alpha8 was the more potent subtype, synergistic and antagonistic antiproliferative effects were also observed in certain combinations of IFN-alpha2 and IFN-alpha8. To analyze the interactions between IFN-alpha2 and IFN-alpha8, the receptor-binding kinetics of different combinations of IFN-alpha2 and IFN- alpha8 to the IFN-alpha receptors, IFNAR-1 or IFNAR-2, were measured using a surface plasmon resonance-based biosensor. Unexpectedly, the receptor binding kinetics to IFNAR-2 but not to IFNAR-1 were mutually related to antiproliferative activity and increase in the binding speed (K(a)) for IFNAR-2. Moreover, we observed the increased fluorescence intensity (FI) of biotin-labeled IFN-alpha8 to IFNAR-2 by receptor binding inhibition assay with unlabeled IFN-alpha2 but not the other combinations. These findings indicate that the binding manner of IFN-alpha8 for IFNAR-2 is different from that of IFN-alpha2, suggesting that binding of IFN-alpha8 rather than binding of IFN-alpha2 to IFNAR-2 leads to activation and subsequent antiproliferative activity despite the same antiviral activity in RCC.

Role of p53 in the inhibitory effects of interferon-alpha subtypes on proliferation of hepatocellular carcinoma cells

While interferon-alpha (IFN-alpha) subtypes share a common specific receptor composed of two subunits, interferon-alpha receptor (IFNAR)-1 and IFNAR-2, their subtype activities are exhibited via several intracellular signaling pathways and thus subsequently show different biological effects. Anti-proliferative effects of single treatment with IFN-alpha subtypes or 5-fluorouracil (FU), and of combined treatment with each IFN-alpha subtype and 5-FU were examined on three hepatocellular carcinoma cell lines, HepG2, HLE and PLC/PRF/5. HepG2 and PLC/PRF/5 cells were susceptible to the combination treatment, but HLE cells were not. Proliferation of PLC/PRF/5 cells was also inhibited by the IFN-alpha subtypes singly. In addition, apoptosis was observed in HepG2 cells upon treatment with 5-FU alone and with the combination treatment, and in PLC/PRF/5 cells after single treatment with the IFN-alpha subtypes and after the combination treatment. IFN-alpha subtypes induced cell cycle arrest in the G2/M phase in HepG2 and PLC/PRF/5. Analyses by Western blotting and immunoprecipitation revealed increased p53 phosphorylation in HepG2 and PLC/PRF/5 cells but not in HLE cells after combined treatment. Single treatment with IFN-alpha subtypes promoted p53 activation only in PLC/PRF/5 cells. These results propose that IFN-alpha subtypes induce cells to undergo apoptosis through p53 activation directly and indirectly, in collaboration with 5-FU, further suggesting the presence of distinct signal pathways for IFN-alpha-induced apoptosis.

Functional expression of human type I interferon receptors in the mouse liver

We expressed human type I interferon (IFN) receptors (IFNAR) in mice and investigated their signaling. Using a hydrodynamics-based delivery method, vectors containing the genes for IFNAR1 and IFNAR2 were transferred into mice. Six hours after gene-transfer, mice were intravenously injected with human IFN-alpha at 10,000 IU. IFNAR1 and IFNAR2 were both expressed in the liver, but not spleen or lung. The receptors were coexpressed in single liver cells. One hour after IFN-alpha injection, the phosphorylation status of signal transducer and activator of transcription factor 1 (STAT1), a key molecule of IFN signaling, was determined. Phosphotyrosine-STAT1 (p-STAT1), localized to the nucleus of IFNAR-expressing cells, was increased in the livers of IFNAR gene-transferred mice but not in control vector-transferred animals. In conclusion, functional human IFNAR can be delivered to the mouse liver, resulting in an increase in p-STAT1 levels following human IFN-alpha stimulation.

Variations in the unstructured C-terminal tail of interferons contribute to differential receptor binding and biological activity

Type I interferons (IFNs) elicit antiviral, antiproliferative and immunomodulatory properties in cells. All of them bind to the same receptor proteins, IFNAR1 and IFNAR2, with different affinities. While the 13 known IFNalphas are highly conserved, the C-terminal unstructured tail was found to have large variation in its net charge, from neutral to +4. This led us to speculate that the tail may have a role in modulation of the IFN biological activity, through fine-tuning the binding to IFNAR2. To evaluate this hypothesis, we replaced the tail of IFNalpha2 with that of IFNalpha8 and IFNbeta tails, or deleted the last five residues of this segment. Mutations to the more positively charged tail of IFNalpha8 resulted in a 20-fold higher affinity to IFNAR2, which results in a higher antiviral and antiproliferative activity. Double and multiple mutant cycle analysis placed the tail near a negatively charged loop on IFNAR2, comprising of residues Glu 132-134. Deleting the tail resulted in only twofold reduction in binding compared to the wild-type. Next, we modeled the location of the tail using a two-step procedure: first we generated 200 models of the tail docked on IFNAR2 using HADDOCK, second the models were scored according to the fit between experimentally determined rates of association of nine mutant complexes, and their calculated rates using the PARE software. From the results we suggest that the unstructured tail of IFNalpha is gaining a specific structure in the bound state, binding to a groove below the 132-134 loop in IFNAR2.

Repeated regression of pulmonary metastases from renal cell carcinoma after treatment using different interferon-alpha preparations

A 49-year-old man with pulmonary metastasis from renal cell carcinoma (RCC) was treated with recombinant IFN-alpha2b (Intron A). A complete response was achieved within 4 months and thereafter persisted for 5 years until he developed another lung lesion. Interleukin-2 (Imunace) was administered without any response. Finally, he was treated by natural IFN-alpha (OIF). The pulmonary lesion achieved a partial response after 11 months of treatment. Because IFN-alpha preparations include different subtypes, changing the use of IFN-alpha preparations may thus be a potentially useful option for the successful immunotherapy of RCC.

Correlation between the anti-virus-induced cytopathic effect activity of interferon-alpha subtypes and induction of MxA protein in vitro

There are several interferon-alpha (IFN-alpha) subtypes. Mechanism of disparity in biological effects among members of IFN-alpha subtypes remains unexplained. Biological activity of IFN-alpha is mediated in part by induction of intracellular antiviral proteins. We studied whether differences in biologic effects of IFN-alpha subtypes may rely on their antiviral protein inducing effect. Intracellular induction of MxA protein and anti-virus-induced cytopathic effect (CPE) activity of 11 IFN-alpha subtypes in human amnion WISH cells have been studied. MxA protein quantitation in cell lysates was performed by immunochemiluminescence assay and anti-virus-induced CPE activity was assessed by protection against vesicular stomatitis virus (VSV)-induced CPE. Range of MxA values was high when cells were treated with 10 and 100 IU/ml of each IFN-alpha subtype. Levels of MxA correlated with anti-VSV-induced CPE obtained with 10 IU/ml IFN-alpha subtype. Together our data show a disparity in MxA-inducing activity of IFN-alpha subtypes and suggest that differences in anti-VSV-induced CPE of IFN-alpha subtypes in WISH cells can be related to their different ability to induce MxA.

Quantification of different human alpha interferon subtypes and pegylated interferon activities by measuring MxA promoter activation

Alpha interferons (alpha-IFNs) are potent biologically active proteins synthesized and secreted by somatic cells during viral infection. Quantification of alpha-IFN concentrations in biological samples is used for diagnosis. More recently, recombinant IFNs have been used as antiviral, antiproliferative, and immunomodulatory therapeutic agents, and particularly for the treatment of chronic hepatitis C virus infection. For this purpose, IFN has recently been coupled to polyethylene glycol (PEG) to improve the pharmacokinetic properties. The measure of alpha-IFN in biological samples from treated patients could be useful to ensure compliance to therapy and the true IFN activity in relation to viral decay during follow-up. In particular, it could be used to monitor the PEG-IFN concentration in patients treated for hepatitis C virus infection. The most frequently used test is a bioassay based on the antiviral property of the IFN, but the assay is not highly reproducible. Here, we present a reporter test based on MxA promoter activation of chloramphenicol acetyltransferase expression (Mx-CAT). MxA is an antiviral protein induced and tightly regulated by alpha-IFN. The Mx-CAT assay showed good reproducibility of 15% and was suitable to quantify PEG-IFN and numerous other alpha-IFN subtypes as well, despite a differential MxA promoter activation in relation with the subtype. A good correlation was obtained with the reporter assay and a commercial enzyme-linked immunosorbent assay on samples from treated patients. This test could be useful for monitoring IFN therapy of chronically infected hepatitis C virus-infected patients treated with the standard IFN, PEG-IFN, and probably forthcoming recombinant IFNs.

Effects of interferon-alpha subtypes on the TH1/TH2 balance in peripheral blood mononuclear cells from patients with hepatitis virus infection-associated liver disorders

Interferon-alpha (IFN-alpha) has recently been shown to modulate in vitro T helper (Th) 1-driven responses in the peripheral blood mononuclear cells (PBMC) of patients with hepatitis B virus or C virus infection. In this study, we examined the in vitro effects of IFN-alpha subtypes (IFN-alpha1, -alpha2, -alpha5, -alpha8, and -alpha10) on the Th1/Th2 balance in PBMC obtained from patients with hepatitis virus infection-associated liver disorders and chronic hepatitis (CH), in comparison with the effect on healthy control volunteer PBMC. The Th1-type cell percentages and Th1/Th2 ratios were significantly higher in the PBMC of patients when compared with controls both before and after cultivation in vitro, with the IFN-alpha subtypes. The IFNalpha-5 induced an increase in the Th2-type cell percentages in both control and patient PBMC, resulting in that IFN-alpha5 lowered the Th1/Th2 ratio in patients with CH. Furthermore, statistical analysis revealed that IFN-alpha8 significantly promoted an increase in the Th1/Th2 ratios of PBMC from patients with CH and liver cirrhosis (LC) but not that of PBMC from patients with LC-hepatocellular carcinoma (HCC) and HCC. These findings imply that hepatitis virus infection and its disease status modify the effects of IFN-alpha subtypes on Th1 and Th2 immune balance in patients. Our findings should help to elucidate the mechanisms underlying successful IFN therapy for hepatitis virus infection and prevention of hepatocellular carcinogenesis.

IFN-alpha5 mediates stronger Tyk2-stat-dependent activation and higher expression of 2',5'-oligoadenylate synthetase than IFN-alpha2 in liver cells

Interferon-alpha5 (IFN-alpha5) is the main IFN-alpha subtype expressed in the liver. Hepatitis C virus (HCV) infection is associated with low IFN-alpha5 mRNA levels, possibly reflecting an escape mechanism of the virus. In this work, we sought to compare IFN-alpha2 and IFN-alpha5 with respect to activation of early cell signaling cascades and induction of antiviral genes in the human hepatoma HepG2 and Huh7 cell lines. We found that the Tyr701 phosphorylation kinetics of Stat1 mediated by IFN stimulation was higher when cells were incubated with IFN-alpha5 than when using IFN-alpha2. Similarly, Tyr(1054/1055) phosphorylation kinetics of Tyk2 were more intense after exposure to IFN-alpha5 than when using IFN-alpha2. Concomitantly, Tyr705 phosphorylation of Stat3 was higher after stimulation with IFN-alpha5 than with IFN-alpha2. In parallel to these findings, the mRNA levels of the antiviral IFN-inducible gene 2',5'-oligoadenylate synthetase were higher in cell samples treated with IFN-alpha5 than with IFN-alpha2. These findings suggest that interaction of IFN-alpha5 and IFN-alpha2 subtypes with IFN type I receptor occurs differently, and this affects the intensity of expression of antiviral genes. In conclusion, our data show that in hepatocytic cells, IFN-alpha5 induces stronger signaling and higher expression of antiviral genes than IFN-alpha2. These data warrant clinical trials to evaluate the efficacy of IFN-alpha5 in chronic viral hepatitis.

A flow cytometric method for determination of the interferon receptor IFNAR2 subunit in peripheral blood leukocyte subsets

INTRODUCTION

It is expected that expression levels in the peripheral blood mononuclear cells (PBMC) of IFNAR2, a subunit of the interferon (IFN) receptor, may be a marker for predicting IFN response. In the present study, we have established a rapid and convenient method for assaying IFNAR2, using flow cytometry.

METHODS

Fifty microliters of whole blood from healthy volunteers was treated with an anti-IFNAR2 antibody and stained with a Fluorescein isothiocyanate (FITC)-conjugated secondary antibody. In addition, the cells were stained with subset-specific antibodies conjugated with phycoerythrin (PE) and PE covalently linked to cyanin 5 at the same time. The mean FITC-fluorescence intensities were analyzed separately by gating on subset-specific regions.

RESULTS

IFNAR2 was detected in most lymphocytes, monocytes, and granulocytes, although IFNAR2 expression was higher in the monocytes and granulocytes than in the lymphocytes. The intra- and interdaily variations of IFNAR2 in lymphocytes, monocytes, and granulocytes were small. Among the lymphocyte subsets, IFNAR2 showed high expression in natural killer (NK) cells and low expression in T lymphocytes. The effect of IFN-alpha on IFNAR2 expression was examined in vitro. A down-regulation of IFNAR2 was observed by IFN-alpha above 100 IU/ml.

DISCUSSION

This assay may be useful for examining IFNAR2 in various leukocyte subsets, separately, as well as providing a rapid and easy method for monitoring expression of type I IFN receptors.

Comparative analysis of IRF and IFN-alpha expression in human plasmacytoid and monocyte-derived dendritic cells

Plasmacytoid dendritic cells (PDC) produce high levels of type I IFN upon stimulation with viruses, while monocytes and monocyte-derived dendritic cells (MDDC) produce significantly lower levels. To find what determines the high production of type I IFN in PDC, we examined the relative levels of IRF transcription factors, some of which play critical roles in the induction of IFN. Furthermore, to determine whether the differences could result from expression of distinct IFNA subtypes, the profile of IFNA genes expressed was examined. PDC responded equally well to stimulation with HSV-1 and Sendai virus (SV) by producing high levels of type I IFN, whereas the MDDC and monocyte response to SV were lower, and neither responded well to HSV-1. All three populations constitutively expressed most of the IRF genes. However, real-time RT-PCR demonstrated increased levels of IRF-7 transcripts in PDC compared with monocytes. As determined by intracellular flow cytometry, the PDC constitutively expressed significantly higher levels of IRF-7 protein than the other populations while IRF-3 levels were similar among populations. Analysis of the profile of IFNA genes expressed in virus-stimulated PDC, monocytes and MDDC demonstrated that each population expressed IFNA1 as the major subtype but that the range of the subtypes expressed in PDC was broader, with some donor and stimulus-dependent variability. We conclude that PDC but not MDDC are uniquely preprogrammed to respond rapidly and effectively to a range of viral pathogens with high levels of IFN-alpha production due to the high levels of constitutively expressed IRF-7.

Differential expression of IFN-alpha subtypes in human PBMC: evaluation of novel real-time PCR assays

Studies of the human IFN-alpha subtype system have been hampered by the lack of efficient procedures to quantify and differentiate the expression of the highly homologous IFN-alpha subtypes. Here we evaluate four novel real-time PCR assays for the specific detection and quantification of IFN-alpha mRNA for the subtypes alpha(2), alpha(6), alpha(8) and alpha(1/13) in a combined assay in human peripheral blood mononuclear cells (PBMC). This included (a) the selection of beta-glucuronidase (GUS) as a suitable housekeeping gene for relative quantification; (b) verification of the specificity by using human DNA of different IFN-alpha subtypes; and (c) comparison of the amplification efficiencies among the different assays. This highly sensitive method allows the detection of low-level, constitutive IFN-alpha mRNA and shows differences in the composition of constitutive IFN-alpha subtypes compared to other cell types (HeLa and HEp-2). The in vitro stimulation of PBMC with Newcastle disease virus (NDV), Respiratory syncytial virus (RSV) or an inactivated Herpes simplex (HSV) preparation leads to the transcriptional induction of all IFN-alpha subtypes investigated but to different expression levels. Among the subtypes detected, IFN-alpha(13/1) and alpha(2) are the major transcripts followed by alpha(8), and finally alpha(6) as a minor transcribed subtype. Time-kinetics of IFN-alpha transcriptional activation also revealed variations in the course of IFN-alpha transcription between NDV, RSV or HSV. The data obtained from the real-time PCR assays correlated well with IFN-alpha(2) protein release. In conclusion, we have demonstrated the suitability and reliability of new real-time PCR assays for the rapid and efficient analysis of IFN-alpha subtype expression.

Serum interferon (IFN)-neutralizing antibodies and bioactivities of IFNs in patients with severe type II essential mixed cryoglobulinemia

The efficacy of alpha interferon (IFN-alpha) in the treatment of severe type II essential mixed cryoglobulinemia (EMC) has been reported previously. In some patients, the development of neutralizing antibodies to recombinant IFN-alpha (rIFN-alpha) can affect the clinical response achieved with rIFN-alpha; a second treatment with natural IFN-alpha preparations may reinduce the clinical response. In the present study the ability of leukocyte IFN (LeIFN) to restore the response was investigated from a pharmacodynamic viewpoint. Specifically, the pharmacodynamic profiles of different IFN-alpha preparations were studied by measuring the serum neopterin levels and the levels of expression of protein MxA mRNA in in vivo peripheral blood mononuclear cells in two patients with EMC whose resistance to rIFN-alpha2a treatment increased concomitantly with the development of neutralizing antibodies. These markers were measured before injection and at 24 and 48 h after a single injection of rIFN-alpha2a, consensus IFN [(C)IFN], or LeIFN. No increase or only a slight increase in MxA mRNA levels was detectable after administration of rIFN-alpha2a or (C)IFN, whereas a significant increase (>/=10-fold) in MxA mRNA expression was recorded following administration of LeIFN. The neutralizing antibodies to rIFN-alpha2a cross-react with (C)IFN. Sera from these patients neutralized most but not all of the subtypes present in the natural IFN-alpha (LeIFN) mixture, and no significant increase in neopterin levels was observed after these patients were switched to LeIFN treatment. In summary, the data demonstrate that the problem of neutralizing antibodies still exists and that LeIFN may induce an increase in the level of MxA mRNA expression but not an increase in neopterin levels in patients who are resistant to treatment with rIFN-alpha2a or (C)IFN.

The anti-tumor activities of interferon (IFN)-alpha in chronic myelogenous leukaemia (CML)-derived cell lines depends on the IFN-alpha subtypes

Here we report on the anti-tumor effects of five interferon (IFN)-alpha subtypes, alpha1, alpha2, alpha5, alpha8, and alpha10 in chronic myelogenous leukaemia (CML)-derived cell lines. All of the CML cells can respond to IFN-alpha although the anti-tumor effects of IFN-alpha depend on the target cell and on the type of IFN-alpha subtype used. Proliferation assays showed that IFN-alpha8 was substantially more effective than the other four IFN-alpha subtypes. IFN-alpha8 was the most potent at upregulating immunomodulatory molecule expression while IFN-alpha1 was least potent. These data indicate in vitro distinctions between IFN-alpha subtypes that should be appreciated more in the clinic.

Characterization of the antitumor activities of IFN-alpha8 on renal cell carcinoma cells in vitro

Interferon-alpha (IFN-alpha) has a number of therapeutic applications in the treatment of various human cancers and diseases of viral origin. IFN-alpha includes several subtypes, and little has been reported on the biologic properties of the individual subtypes. Here, we report on the individual antitumor effects of five IFN-alpha subtypes, alpha1, alpha2, alpha5, alpha8, and alpha10, against six renal cell carcinoma (RCC) cell lines in vitro. Among the subtypes, IFN-alpha8 most potently inhibited cell proliferation and delayed the G(1)/S transition. Synergistic induction of apoptosis was shown in two of the RCC cell lines when treated with the combination of IFN-alpha and IFN-gamma rather than with either IFN-alpha or IFN-gamma alone. IFN-alpha8 was most effective in the induction of apoptosis when combined with IFN-gamma. In addition, IFN-alpha8 had the strongest ability to upregulate HLA class II antigen expression in the subtypes examined. These data indicate that subtypes of IFN-alpha have disparate antitumor effects in vitro, and in vitro distinctions among the IFN-alpha subtypes should be appreciated more in clinical application.