An overview of the interferon system: signal transduction and mechanisms of action

The role of Type I interferons in the pathogenesis of foot-and-mouth disease virus in cattle: A mathematical modelling analysis

Type I interferons (IFN) are the first line of immune response against infection. In this study, we explore the interaction between Type I IFN and foot-and-mouth disease virus (FMDV), focusing on the effect of this interaction on epithelial cell death. While several mathematical models have explored the interaction between interferon and viruses at a systemic level, with most of the work undertaken on influenza and hepatitis C, these cannot investigate why a virus such as FMDV causes extensive cell death in some epithelial tissues leading to the development of lesions, while other infected epithelial tissues exhibit negligible cell death. Our study shows how a model that includes epithelial tissue structure can explain the development of lesions in some tissues and their absence in others. Furthermore, we show how the site of viral entry in an epithelial tissue, the viral replication rate, IFN production, suppression of viral replication by IFN and IFN release by live cells, all have a major impact on results.

Immunomodulatory activity of manganese dioxide nanoparticles: Promising for novel vaccines and immunotherapeutics

Manganese (Mn), a nutrient inorganic trace element, is necessary for a variety of physiological processes of animal body due to their important roles in oxidative regulation effects and other aspects of activities. Moreover, manganese ion (Mn²⁺) has widely reported to be crucial for the regulations of different immunological responses, thus showing promising application as potential adjuvants and immunotherapeutics. Taking the advantages of Mn-based biological and immunological activities, Manganese dioxide nanoparticles (MnO₂ NPs) are a new type of inorganic nanomaterials with numerous advantages, including simple preparation, low cost, environmental friendliness, low toxicity, biodegradable metabolism and high bioavailability. MnO₂ NPs, as a kind of drug carrier, have also shown the ability to catalyze hydrogen peroxide (H₂O₂) to produce oxygen (O₂) under acidic conditions, which can enhance the efficacy of radiotherapy, chemotherapy and other therapeutics for tumor treatment by remodeling the tumor microenvironment. More importantly, MnO₂ NPs also play important roles in immune regulations both in innate and adaptive immunity. In this review, we summarize the biological activities of Manganese, followed by the introduction for the biological and medical functions and mechanisms of MnO₂ NPs. What's more, we emphatically discussed the immunological regulation effects and mechanisms of MnO₂ NPs, as well as their potentials to serve as adjuvants and immunomodulators, which might benefit the development of novel vaccines and immunotherapies for more effective disease control.

Type I Interferons Enhance the Repair of Ultraviolet Radiation-Induced DNA Damage and Regulate Cutaneous Immune Suppression

Type I interferons (IFNs) are important enhancers of immune responses which are downregulated in human cancers, including skin cancer. Solar ultraviolet (UV) B radiation is a proven environmental carcinogen, and its exposure contributes to the high prevalence of skin cancer. The carcinogenic effects of UV light can be attributed to the formation of cyclobutane pyrimidine dimers (CPD) and errors in the repair and replication of DNA. Treatment with a single dose of UVB (100 mJ/cm2) upregulated IFNα and IFNβ in the skin of C57BL/6 mice. IFNα and IFNβ were predominantly produced by CD11b+ cells. In mice lacking the type I IFN receptor 1 (IFNAR1), the repair of CPD following cutaneous exposure to a single dose of UVB (100 mJ/cm2) was decreased. UVB induced the expression of the DNA repair gene xeroderma pigmentosum A (XPA) in wild-type (WT) mice. In contrast, such treatment in IFNAR1 (IFNAR1-/-) mice downregulated XPA. A local UVB regimen consisting of UVB radiation (150 mJ/cm2) for 4 days followed by sensitization with hapten 2,4, dinitrofluorobenzene (DNFB) resulted in significant suppression of immune responses in both WT and IFNAR1-/- mice. However, there were significantly higher CD4+CD25+Foxp3+ regulatory T-cells in the draining lymph nodes of IFNAR1-/- mice in comparison to WT mice. Overall, our studies reveal a previously unknown action of type I IFNs in the repair of photodamage and the prevention of UVB-induced immune suppression.

Manganese Breaks the Immune Tolerance of HBs-Ag

Background

Manganese (Mn²⁺⁾ has been shown to promote type I interferon (IFN) production and activate the cyclic GMP-AMP synthase (cGAS)/Stimulator of Interferon Genes (STING) signaling pathway, suggesting that Mn²⁺ could be used as an adjuvant for vaccination.

Methods

In present study, the effects of Mn²⁺ on vaccination against hepatitis B virus (HBV) were evaluated. We treated mouse hepatocytes and kuppfer cells with Mn²⁺ with or without adeno-associated virus (AAV)–HBV infection. Expression of IFN-α and IFN-β and activation of TBK1 and IRF3 were monitored. Wild-type and STING^-/- mice were treated with Mn²⁺ and then infected with AAV-HBV. Serum levels of HBV surface antigen (HBsAg), alanine aminotransferase (ALT) activity, IFN-α, and IFN-β were detected. Lymphocyte infiltration in the liver was evaluated. HBsAg-Tg mice were vaccinated with Mn²⁺ and HBsAg. The serum levels of HBsAg antibody, alanine transaminase activity, and IFN-β were monitored after vaccination.

Results

Mn²⁺ promoted IFN-α and IFN-β production in mouse hepatocytes and kuppfer cells. Mn²⁺ failed to promote IFN-α and IFN-β production in kuppfer cells deficient in STING. Mn²⁺ promoted activation/phosphorylation of TBK1 and IRF3 during AAV-HBV infection. Mn²⁺ decreased serum levels of HBsAG, increased serum levels of alanine aminotransferase (ALT), IFN-α and IFN-β, and enhanced lymphocyte infiltration and the percentage of IFN-γ-producing CD8⁺ T cells in the liver of AAV-HBV-infected mice. In contrast, Mn²⁺ treatment did not affect serum levels of HBsAG, ALT, IFN-α, or IFN-β in STING-deficient mice.

Conclusions

Mn²⁺ promoted HBsAG antibody, ALT, and IFN-β production after HBsAG immunization. Mn²⁺ promoted type I IFN production in AAV-HBV infection and HBsAG immunization and could be used as an adjuvant for vaccination.

How ISG15 combats viral infection

Interferon (IFN)-stimulated gene product 15 (ISG15) is a ubiquitin-like protein critical for the control of microbial infections. ISG15 appears to serve a wide variety of functions, which regulate multiple cellular responses contributing to the development of an antiviral state. ISG15 is a versatile molecule directly modulating both host and virus protein function which regulate many signaling pathways, including its own synthesis. Here we review the various roles ISG15 plays in the antiviral immune response, and examine the mechanisms by which viruses attempt to mitigate or exploit ISG15 activity.

Endogenous double-stranded Alu RNA elements stimulate IFN-responses in relapsing remitting multiple sclerosis

Various sensors that detect double-stranded RNA, presumably of viral origin, exist in eukaryotic cells and induce IFN-responses. Ongoing IFN-responses have also been documented in a variety of human autoimmune diseases including relapsing-remitting multiple sclerosis (RRMS) but their origins remain obscure. We find increased IFN-responses in leukocytes in relapsing-remitting multiple sclerosis at distinct stages of disease. Moreover, endogenous RNAs isolated from blood cells of these same patients recapitulate this IFN-response if transfected into naïve cells. These endogenous RNAs are double-stranded RNAs, contain Alu and Line elements and are transcribed from leukocyte transcriptional enhancers. Thus, transcribed endogenous retrotransposon elements can co-opt pattern recognition sensors to induce IFN-responses in RRMS.

Mathematical model of immune response to hepatitis B

A new detailed mathematical model for dynamics of immune response to hepatitis B is proposed, which takes into account contributions from innate and adaptive immune responses, as well as cytokines. Stability analysis of different steady states is performed to identify parameter regions where the model exhibits clearance of infection, maintenance of a chronic infection, or periodic oscillations. Effects of nucleoside analogues and interferon treatments are analysed, and the critical drug efficiency is determined.

Anti-metastatic functions of type 1 interferons: Foundation for the adjuvant therapy of cancer

The anti-tumorigenic effects that type 1 interferons (IFN1) elicited in the in vitro studies prompted consideration of IFN1 as a potent candidate for clinical treatment. Though not all patients responded to IFN1, clinical trials have shown that patients with high risk melanoma, a highly refractory solid malignancy, benefit greatly from intermediate IFN1 treatment in regards to relapse-free and distant-metastasis-free survival. The mechanisms by which IFN1 treatment at early stages of disease suppress tumor recurrence or metastatic incidence are not fully understood. Intracellular IFN1 signaling is known to affect cell differentiation, proliferation, and apoptosis. Moreover, recent studies have revealed specific IFN1-regulated genes that may contribute to IFN1-mediated suppression of cancer progression and metastasis. In concert, expression of these different IFN1 stimulated genes may impede numerous mechanisms that mediate metastatic process. Though, IFN1 treatment is still utilized as part of standard care for metastatic melanoma (alone or in combination with other therapies), cancers find the ways to develop insensitivity to IFN1 treatment allowing for unconstrained disease progression. To determine how and when IFN1 treatment would be most efficacious during disease progression, we must understand how IFN1 signaling affects different metastasis steps. Here, we specifically focus on the anti-metastatic role of endogenous IFN1 and parameters that may help to use pharmaceutical IFN1 in the adjuvant treatment to prevent cancer recurrence and metastatic disease.

Attenuation of IFN-γ-induced B7-H1 expression by 15-deoxy-delta(12,14)-prostaglandin J2 via downregulation of the Jak/STAT/IRF-1 signaling pathway

AIM

B7-H1, which belongs to the B7 family of costimulatory molecules, is implicated in the ability of tumors to evade the host immune response. The development of evasion mechanisms within the tumor microenvironment may be responsible for poor therapeutic responses. In this manuscript, we report that the 15-deoxy-δ(12,14)-prostaglandin J2 (15d-PGJ2), peroxisome proliferator-activated receptor gamma (PPARγ) activator leads to the downregulation of the cancer-associated expression of B7-H1 in response to interferon-gamma (IFN-γ) and the associated signaling cascades.

MAIN METHODS

The expression of B7-H1 from IFN-γ-induced B16F10 melanoma cells was measured with flow cytometric analysis. The regulatory mechanisms of 15d-PGJ2 on cellular signaling pathways were examined using Western blot and electrophoretic mobility shift assays.

KEY FINDINGS

The flow cytometric analysis revealed that the B7-H1 costimulatory molecule is significantly upregulated in B16F10 melanoma cells by stimulation with IFN-γ. However, 15d-PGJ2 strongly downregulates B7-H1 expression in IFN-γ-stimulated B16F10 melanoma cells. Furthermore, the significant damping effect of 15d-PGJ2 on B7-H1 expression involves the inhibition of the tyrosine phosphorylation of Janus kinase (Jak) and signal transducer(s) and activator(s) of transcription (STAT) and, thereby, the interferon regulatory factor-1 (IRF-1) trans-activation of STAT. These effects of 15d-PGJ2 were not abrogated by the PPARγ antagonist GW9662, indicating that they occur through a PPARγ-independent mechanism.

SIGNIFICANCE

In this study, we demonstrate that 15d-PGJ2 suppresses the IFN-γ-elicited expression of B7-H1 by the inhibition of IRF-1 transcription via the Jak/STAT signaling pathway through a PPARγ-independent mechanism in mouse melanoma cells.

Functional Characterization of Interferon Regulation Element of Hepatitis B virus Genome In Vivo

The roles of interferon regulatory element (IRE) in Hepatitis B virus (HBV) genome on inhibitory effect of interferon against HBV are controversial in vitro. This study aimed to determine the functional characterization of HBV-IRE sequence in vivo. Wild-type or IRE-mutant HBV replication-competent mice were firstly established, and mice were subquently treated with polyinosinic-polytidylin acid (polyI.C) or phosphate-buffered saline via intraperitoneal. Results showed that PolyI.C inhibited viral replication, and increased the level of 2',5'-oligoadenylate synthase mRNA transcripts, a marker of INF-α/β induction. Between wild-type and IRE-mutant HBV replication-competent mice, the levels of HBV-RNA and HBV-DNA replication intermediates were similar. After PolyI.C treatment, the decreasing of HBV-RNA was similar between two groups, but HBV-DNA replication intermediates decreased significantly less in IRE-mutant than wild-type HBV replication-competent mice. These findings suggested that IRE mutant reduced the inhibitory effect of interferon on HBV replication, which played a role in antiviral effect of interferon against HBV.

Nicotine, IFN-γ and retinoic acid mediated induction of MUC4 in pancreatic cancer requires E2F1 and STAT-1 transcription factors and utilize different signaling cascades

Background

The membrane-bound mucins are thought to play an important biological role in cell–cell and cell–matrix interactions, in cell signaling and in modulating biological properties of cancer cell. MUC4, a transmembrane mucin is overexpressed in pancreatic tumors, while remaining undetectable in the normal pancreas, thus indicating a potential role in pancreatic cancer pathogenesis. The molecular mechanisms involved in the regulation of MUC4 gene are not yet fully understood. Smoking is strongly correlated with pancreatic cancer and in the present study; we elucidate the molecular mechanisms by which nicotine as well as agents like retinoic acid (RA) and interferon-γ (IFN-γ) induce the expression of MUC4 in pancreatic cancer cell lines CD18, CAPAN2, AsPC1 and BxPC3.

Results

Chromatin immunoprecipitation assays and real-time PCR showed that transcription factors E2F1 and STAT1 can positively regulate MUC4 expression at the transcriptional level. IFN-γ and RA could collaborate with nicotine in elevating the expression of MUC4, utilizing E2F1 and STAT1 transcription factors. Depletion of STAT1 or E2F1 abrogated the induction of MUC4; nicotine-mediated induction of MUC4 appeared to require α7-nicotinic acetylcholine receptor subunit. Further, Src and ERK family kinases also mediated the induction of MUC4, since inhibiting these signaling molecules prevented the induction of MUC4. MUC4 was also found to be necessary for the nicotine-mediated invasion of pancreatic cancer cells, suggesting that induction of MUC4 by nicotine and other agents might contribute to the genesis and progression of pancreatic cancer.

Conclusions

Our studies show that agents that can promote the growth and invasion of pancreatic cancer cells induce the MUC4 gene through multiple pathways and this induction requires the transcriptional activity of E2F1 and STAT1. Further, the Src as well as ERK signaling pathways appear to be involved in the induction of this gene. It appears that targeting these signaling pathways might inhibit the expression of MUC4 and prevent the proliferation and invasion of pancreatic cancer cells.

Histology, immunocytochemistry and qRT-PCR analysis of Atlantic salmon, Salmo salar L., post-smolts following infection with infectious pancreatic necrosis virus (IPNV)

Infectious pancreatic necrosis (IPN) is a very serious viral disease in terms of its impact on production of Atlantic salmon, Salmo salar L., fry and post-smolts. Post-smolts of Atlantic salmon were injected with infectious pancreatic necrosis virus (IPNV) and cohabited with naive fish to produce natural infection. Cohabitant fish were sampled every 2 days, up to day 36 post-infection (p.i.). From 90 cohabitant fish, 11 (12.2%) were positive by immunohistochemistry (IHC). The first detection of IPNV by IHC occurred on day 16 p.i. which coincided with the onset of mortality in this group. Besides the pancreas, the liver was found to be a key target organ for IPNV. For the first time, the virus was observed in the islets of Langerhans and in the kidney corpuscles of Stannius which suggests that the virus could affect the fish's metabolism. The liver of two fish, which showed the most widespread presence of IPNV by IHC, had a pathology including focal necrosis and widespread presence of apoptotic hepatocytes, many of which did not stain for virus by IHC. Up-regulation of cytokine gene expression was found only in the IHC-positive (IHC+ve) fish and reflected the level of infection as determined by IHC positivity of the liver. In most fish, interferon (IFN), Mx, γIFN and γIP were up-regulated in liver and kidney, while only IFN and Mx were up-regulated in gill. IL1β and TNFα were not induced in any tissue. The gill showed variable levels of constitutive expression of IL1β and γIFN. The two fish with liver pathology had the highest level of IFN expression, especially relative to the level of Mx expression, in the liver compared with the other IHC+ve fish which did not have a liver pathology. The results suggest that following widespread infection of hepatocytes, the cells may over-produce IFN, resulting in apoptosis of neighbouring cells with subsequent death from liver failure.

A whole genome transcriptional analysis of the early immune response induced by live attenuated and inactivated influenza vaccines in young children

The protective mechanisms of influenza vaccines in young children are not completely understood. A phase 2 clinical study was conducted in 85 children 12-35 months of age to describe and compare the immune responses to live attenuated influenza vaccine (LAIV) with trivalent inactivated influenza vaccine (TIV). To better understand the biology of vaccine effects, oligonucleotide microarrays were employed to measure the genome-wide changes in transcript profiles in whole blood at approximately 7 days after 1 dose of LAIV or TIV. Of the total 265 differentially expressed genes identified in this study, 6 clusters of genes were identified to be tightly coexpressed, many of which are likely modulated by cytokines including type 1 interferons (IFNs) and granulocyte-macrophage colony-stimulating factor. Additional functional analyses revealed that the type 1 IFN pathway and cell cycle regulation-related genes are enriched in the 6 coexpressed gene sets. Promoter characterization of these coexpressed genes also supported this conclusion. Moreover, it is suggested that the IFN-stimulated response element is likely to be a potential bidirectional promoter, and the CCAAT/enhancer-binding protein might cooperate with the E2F transcription factor family in the regulation of the cell cycle in the early immune response induced by the influenza vaccine. Overall, our study clearly indicates that the expression profile changes induced by LAIV are significantly different from those induced by TIV. These results suggest that the pattern of overexpression of type 1 IFN-stimulated genes can potentially be used as a biomarker to identify the early vaccination response of LAIV and may also explain, to a certain extent, previous clinical study observations of LAIV-induced protection against influenza-like illness in the first 2 weeks after administration.

Expression of the costimulatory molecule B7-H3 is associated with prolonged survival in human pancreatic cancer

Background

Costimulatory signaling has been implicated as a potential regulator of antitumor immunity in various human cancers. In contrast to the negative prognostic value of aberrant B7-H1 expression by pancreatic cancer cells, the role of B7-H3 is still unknown. Therefore, we investigated the expression pattern and clinical significance of B7-H3 expression in human pancreatic cancer.

Methods

B7-H3 expression was evaluated by immunohistochemistry in 68 patients with pancreatic cancer who underwent surgical tumor resection. Expression data was correlated with clinicopathologic features and with the number of tumor-infiltrating T cells.

Results

B7-H3 expression was significantly upregulated in pancreatic cancer compared to normal pancreas (p < 0.05). In 60 of 68 examined tumors B7-H3 protein was detectable in pancreatic cancer cells. Patients with high tumor B7-H3 levels had a significantly better postoperative prognosis than patients with low tumor B7-H3 levels (p = 0.0067). Furthermore, tumor B7-H3 expression significantly correlated with the number of tumor-infiltrating CD8+ T cells (p = 0.018).

Conclusion

We demonstrate for the first time that B7-H3 is abundantly expressed in pancreatic cancer and that tumor-associated B7-H3 expression significantly correlates with prolonged postoperative survival. Our findings suggest that B7-H3 might play an important role as a potential stimulator of antitumor immune response in pancreatic cancer.

Clinical significance and regulation of the costimulatory molecule B7-H1 in pancreatic cancer

We investigated the expression pattern and clinical significance of the costimulatory ligands B7-1, B7-2, B7-H1, and B7-DC, and their counter-receptors CTLA-4 and PD-1 in pancreatic cancer. Gene expression of all examined costimulatory molecules was significantly upregulated in pancreatic cancer tissues. B7-1, B7-2, B7-H1, and B7-DC protein was detectable in pancreatic cancer cells. Only the expression of B7-H1 significantly correlated with postoperative survival (p<0.0001). B7-H1 was inducible in cultured pancreatic cancer cells by IFN-gamma and significantly correlated with the level of IFN-gamma expression in human pancreatic cancer tissues (Spearman rho=0.4536,p=0.0029). B7-H1 positive tumors showed an increased prevalence of tumor-infiltrating regulatory T cells (Tregs) compared to B7-H1 negative tumors. Among the investigated costimulatory molecules only tumor-associated B7-H1 seems to be of prognostic relevance in pancreatic cancer. B7-H1 might, therefore, be involved in the downregulation of antitumor responses through regulation of Tregs in pancreatic cancer. Our findings also suggest a dual role of IFN-gamma in antitumor response. Through induction of B7-H1 in pancreatic cancer cells IFN-gamma might contribute to the evasion of antitumor immunity.

Augmentation of effects of interferon-stimulated genes by reversal of epigenetic silencing: potential application to melanoma

Increased expression of genes, silenced by methylation of their promoters, could have relevance for increasing effects of not only interferons (IFNs) but also APO2L/TRAIL, cytotoxics and immunotherapeutics for melanoma and other malignancies. A resistant melanoma cell line, A375, lacked APO2L/TRAIL or apoptosis induction by either IFN-alpha2 or IFN-beta. However, apoptosis was induced by IFNs in A375 cells by 5-aza,2'-deoxycytidine (5-Aza-dC), evaluated based upon the postulate that promoter methylation might be silencing pro-apopoptotic IFN-stimulated genes (ISGs). RASSF1A, commonly methylated at high frequency in many tumors including melanoma, which we discovered to be also an IFN-regulated gene, was increased by 5-Aza-dC. RASSF1A was important in enhancing apoptotic effects of not only IFNs and APO2L/TRAIL but also cisplatin. Unraveling epigenetic regulatory mechanisms, as yet only partially identified, will result in new biological insights and improved strategies for therapeutic use of IFNs or ISGs such as APO2L/TRAIL.

IFN-gamma-induced expression of MUC4 in pancreatic cancer cells is mediated by STAT-1 upregulation: a novel mechanism for IFN-gamma response

MUC4 is a transmembrane mucin, which is aberrantly expressed in pancreatic adenocarcinoma with no detectable expression in the normal pancreas. Here, we present a novel mechanism of IFN-gamma-induced expression of MUC4 in pancreatic cancer cells. Our studies highlight the upregulation of STAT-1 as a basis for MUC4 induction and demonstrate that its activation and upregulation by IFN-gamma are two distinct, albeit temporally integrated, signalling events that drive the selective induction of IRF-1 and MUC4, respectively, within a single cell system. The profile of interferon regulatory factor (IRF)-1 gene induction by IFN-gamma is consistent with its rapid transactivation by phospho-Y701-STAT-1. In contrast, the induction of the MUC4 mucin gene expression is relatively delayed, and occurs only in response to an increase in STAT-1 expression. A progressive binding of STAT-1 to various gamma-interferon-activated sequences (GAS) in the MUC4 promoter is observed in chromatin immunoprecipitation assay, indicating its direct association. Stimulation of STAT-1 expression by double-stranded polynucleotides or ectopic expression is shown to induce MUC4 expression, without Y701 phosphorylation of STAT-1. This effect is abrogated by short interfering RNA (siRNA)-mediated inhibition of STAT-1 expression, supporting further the relevance of STAT-1 in MUC4 regulation. In conclusion, our findings identify a novel mechanism for MUC4 regulation in pancreatic cancer cells and unfold new perspectives on the foundation of IFN-gamma-dependent gene regulation.

Randomized Trial of Adjuvant 13-cis-Retinoic Acid and Interferon Alfa for Patients With Aggressive Skin Squamous Cell Carcinoma

Purpose

To conduct a phase III trial of adjuvant 13-cis-retinoic acid (13cRA) plus interferon alfa (IFN-α) for preventing tumor recurrence and second primary tumors (SPTs) of skin squamous cell carcinoma (SCC) among patients with aggressive skin SCC.

Patients and Methods

Sixty-six patients with aggressive skin SCC were randomly assigned to receive either 6 months of combined 13cRA (1 mg/kg/d orally) and IFN-α (3 × 106 U subcutaneously three times per week) or no adjuvant therapy (control group) after SCC surgery and/or radiation.

Results

At 21.5 months median follow-up, treatment did not improve the time to tumor recurrence and SPT versus control (hazard ratio [HR], 1.13; 95% CI, 0.53 to 2.41), time to tumor recurrence (HR, 1.08; 95% CI, 0.43 to 2.72), or time to SPT (HR, 0.89; 95% CI, 0.27 to 2.93). Adjuvant 13cRA and IFN-α was moderately tolerable; 29% of patients in the treatment arm required dose reductions for grade 3 or 4 toxicities.

Conclusion

Results of this phase III trial do not support 13cRA plus IFN-α for adjuvant therapy of aggressive skin SCC. With high rates of tumor recurrence and SPTs, patients with aggressive skin SCC continue to have an unmet medical need, with devastating mortality, morbidity, and financial consequences. Promising agents with preclinical and early clinical results relevant to aggressive skin SCC deserve a high priority for future clinical drug development.

Modelling dynamics of the type I interferon response to in vitro viral infection

Innate immunity is crucial in the early stages of resistance to novel viral infection. The family of cytokines known as the interferons (IFNs) forms an essential component of this system: they are responsible for signalling that an infection is underway and for promoting an antiviral response in susceptible cells. We construct a spatial stochastic model, parameterized by experimental data and informed by analytic approximation, to capture the dynamics of virus-IFN interaction during in vitro infection of Madin-Darby bovine kidney cell monolayers by Herpes simplex virus 1. The dose dependence of infection progression, subsequent monolayer destruction and IFN-beta production are investigated. Implications for in vivo infections, in particular the priming of susceptible cells by IFN-beta during infection, are considered.

A role for Stat1 in the regulation of lipopolysaccharide-induced interleukin-1beta expression

Because the induction of interleukin-1beta (IL-1beta) is critical to antibacterial host defenses and its excessive generation is a prominent component of sepsis, regulation of this proinflammatory cytokine is a critical factor in the immune response to lipopolysaccharide (LPS). We previously showed that LPS-induced IL-1beta expression was regulated by a Stat1-dependent, nitric oxide (NO)-mediated mechanism. Subsequent in vivo studies showed that whereas Stat1 had a role in the downregulation of IL-1beta expression, it had a more significant effect on its initial induction. Although both interferon-beta (IFN-beta) and IFN-gamma activate Stat1, the early appearance of IFN-beta in the circulation after LPS administration suggested its pivotal role in Stat1-mediated IL-1beta expression in vivo. Further in vitro analysis of peritoneal macrophages from IFN-beta (/), Stat1(/), and caspase-1(/) mice and their wild-type controls following LPS stimulation demonstrated that IL-1beta mRNA was expressed in these mice but not in macrophages from MyD88(/) mice. Despite the presence of IL-1beta mRNA, IL-1beta protein was markedly reduced in the absence of Stat1 activation in macrophages derived from IFN-beta (/) and Stat1(/) mice or in the absence of caspase-1 activity, which itself was dependent on Stat1 activation. These studies support the hypothesis that the expression of IL-1beta requires both the MyD88-dependent induction of IL-1beta mRNA and pro-IL-1beta as well as the MyD88-independent, Stat1-mediated processing of that gene product into active cytokine.

A randomised trial to compare the pharmacokinetic, pharmacodynamic, and antiviral effects of peginterferon alfa-2b and peginterferon alfa-2a in patients with chronic hepatitis C (COMPARE)

BACKGROUND/AIMS

To compare the pharmacokinetics, pharmacodynamics, and antiviral activity of peginterferon alfa-2b and peginterferon alfa-2a in patients with chronic hepatitis C virus genotype 1.

METHODS

Thirty-six patients were randomised to peginterferon alfa-2b (1.5 microg/kg/week) or peginterferon alfa-2a (180 microg/week) for 4 weeks, then in combination with ribavirin (13 mg/kg/day) for a further 4 weeks. The pharmacokinetic profile of both peginterferons, mRNA expression of a selected group of interferon-induced gene transcripts, and serum HCV-RNA levels were assessed.

RESULTS

Patients receiving peginterferon alfa-2b had significantly greater up-regulation of interferon-alfa response genes compared with those receiving peginterferon alfa-2a. Correspondingly, patients treated with peginterferon alfa-2b also had a significantly greater log10 maximum and log10 time-weighted average decrease in serum HCV-RNA. A greater proportion of peginterferon alfa-2b patients achieved a > or = 2.0 log10 reduction in serum HCV-RNA levels by week 8 (72% vs 44% of peginterferon alfa-2a patients, P = 0.09). There was an approximately 16-fold greater exposure to peginterferon in the serum of patients treated with peginterferon alfa-2a.

CONCLUSIONS

These findings suggest that the biological activity, measured by early interferon-induced gene transcripts and early antiviral responsiveness, may have been greater in patients treated with peginterferon alfa-2b despite their lower exposure to the drug compared with patients treated with peginterferon alfa-2a.

Angiogenesis in malignant glioma--a target for antitumor therapy?

The prognosis of malignant gliomas is still dismal despite aggressive treatment attempts. Thus, alternative therapy strategies are needed. Malignant gliomas are upon the best vascularized tumors in humans and their proliferation is hallmarked by a distinct proliferative vascular component. Hence it seems to be a logical consequence to apply anti-angiogenic treatment strategies to malignant gliomas. These treatment strategies have shown promising effects in animal models and some experimental clinical studies. This review gives a short introduction into the molecules involved in angiogenesis of malignant gliomas, it provides an overview of the latest experimental developments of glioma angiogenesis inhibition and discusses the results of clinical anti-angiogenic trials in patients with high grade glioma. Additionally the problem of monitoring the treatment success of an anti-angiogenic therapy is addressed.

Immunomodulatory therapy for ocular inflammatory disease: a basic manual and review of the literature

Corticosteroids are used as first-line treatment for many ocular inflammatory conditions. The risk of adverse effects, however, necessitates conversion to steroid-sparing immunomodulatory therapy (IMT) for disease that is recurrent, chronic, or poorly responsive to treatment. Combination drug treatments with multiple agent 'recipes' are also considered. Immunomodulatory agents include the broad categories of antimetabolites (azathioprine, methotrexate, mycophenolate mofetil), alkylating agents (cyclophosphamide, chlorambucil), T-cell inhibitors (cyclosporine, tacrolimus), and cytokines (interferon alfa). This article reviews and summarizes the evidence for IMT agent use in the treatment of various forms of ocular inflammation.

Interferon regulatory factor-1 is prerequisite to the constitutive expression and IFN-gamma-induced upregulation of B7-H1 (CD274)

Majority of cancer cells upregulate co-inhibitory molecule B7-H1 which confers resistance to anti-tumor immunity, allowing cancers to escape from host immune surveillance. We addressed the molecular mechanism underlying the regulation of cancer-associated B7-H1 expression in response to interferon-gamma (IFN-gamma). Using promoter constructs in luciferase assay, the region between 202 and 320 bp from the translational start site is responsible for B7-H1 expression. Electrophoretic mobility shift assay, site-directed mutagenesis and knockdown experiment using siRNA revealed that interferon regulatory factor-1 (IRF-1) is primarily responsible for the constitutive B7-H1 expression as well as for the IFN-gamma-mediated B7-H1 upregulation in a human lung cancer cell line A549. Additionally, AG490, a Janus activated kinase/signal transducer and activator of transcription inhibitor, greatly abolished the responsiveness of A549 cells to IFN-gamma by reducing the IRF-1 transcription. Our findings support a critical role of IRF-1 in the regulation of constitutive and IFN-gamma-induced expression of B7-H1 in cancer cells.

Therapeutic Implications of Interferon Regulatory Factor (IRF)-1 and IRF-2 in Diffusely Infiltrating Astrocytomas (DIA): Response to Interferon (IFN)-β in Glioblastoma Cells and Prognostic Value for DIA

The precise mechanisms governing the direct effect of IFN-beta, including apoptosis induction, are not yet fully understood. To gain a better insight into these mechanisms, we investigated the signaling pathways focusing particularly on interferon regulatory factor 1 (IRF-1) and IRF-2 in glioblastoma cell lines. Furthermore, we attempted to determine whether or not IRF-1 and IRF-2 act as additional prognostic indicators in diffusely infiltrating astrocytomas (DIA). We first assessed the cytotoxic effects of IFN-beta based on a cell growth study and modified MTT assay, and then quantified the apoptosis using a sandwich enzyme immunoassay following IFN-beta treatment in the cell lines, U-87MG, T98G, and A-172. Subsequently, we carried out an analysis of apoptosis-related molecules as evaluated by densitometric analysis of Western blots, focusing on IRF-1 and IRF-2, and two major initiator caspases, caspase-8 and caspase-9. Furthermore, we assessed the expression of type I IFN receptor, IRF-1, and IRF-2 using immunohistochemical techniques in 63 DIA (15 of WHO grade II, 18 of grade III, and 30 of grade IV), and analyzed their impact on prognosis. An increase in apoptosis was apparent after 48 h of IFN-beta treatment (1 x 10(4) IU/ml) in T98G but not in U-87MG or A-172. IFN-beta treatment for 6 h significantly enhanced the expression of IRF-1 in all three cell lines. However, an enhanced expression of IRF-2 was observed only in the not-most-sensitive, non-apoptosis-induced U-87MG and A-172. While minimal processing of caspase-8 was noted in the three cell lines throughout the experiment, caspase-9 activation was observed in the apoptosis-detected T98G after 48 h of treatment, as indicated by a 1.33-fold increase (P=0.037). On the other hand, the IRF-1 LI and IRF-1/IRF-2 LI ratio were greater in low-grade DAI, and were negatively correlated with the histopathological grade in DIA (P=0.017 and P=0.001, respectively). Furthermore, the IRF-1/IRF-2 LI ratio was negatively correlated with the MIB-1 LI in DIA (P=0.004), and represented an independent and most powerful determinant of overall survival compared to other conventional prognostic factors (P=0.018). However, the relation was not statistically significant when only patients with high-grade DIA were assessed. Our findings suggest that up-regulation of IRF-1 and IRF-2 might be an important determinant of susceptibility to IFN-beta mediated cytotoxicity including apoptosis. Furthermore, the IRF-1/IRF-2 LI ratio may reflect the proliferative state of DIA and constitute an important prognostic marker in DIA. Thus, IRF-1 and IRF-2 could represent one of the therapeutic target sites for the regulation of cell growth in DIA.

Influence of IFN-gamma on gene expression in normal human bronchial epithelial cells: modulation of IFN-gamma effects by dexamethasone

Interferon gamma (IFN-gamma) plays a role in a variety of lung inflammatory responses, and corticosteroids are frequently employed as a treatment in these conditions. Therefore, the effect of IFN-gamma, of the corticosteroid dexamethasone (Dex), or of both on gene expression was studied in normal human bronchial epithelial (NHBE) cells. NHBE cells were exposed to medium alone, IFN-gamma (300 U/ml), Dex (10(-7) M), or both IFN-gamma and Dex for 8 or 24 h. Gene expression was examined using oligonucleotide microarrays. A principal components analysis demonstrated that the IFN-gamma treatment effect was the primary source of differences in the data. With a 5% false discovery rate, of the 66 genes upregulated by IFN-gamma by twofold or greater at 8 h and 287 genes upregulated at 24 h, coincubation with Dex inhibited the expression of 2 genes at 8 h and 45 genes at 24 h. Prominent among these were cytokines and secreted proteins. Dex cotreatment increased expression of 65 of the 376 genes that were inhibited by IFN-gamma by 50% at 24 h. The majority of these genes encode cell cycle or nuclear proteins. Dex alone increased the expression of only 22 genes and inhibited the expression of 7 genes compared with controls at 24 h. The effect of Dex on IFN-gamma-induced changes suggests a specific, targeted effect on IFN-gamma responses that is substantially greater than the effect of Dex alone. Dex had little effect on the immediate early response to IFN-gamma but a significant effect on the late responses.

Effects of alpha-interferon on insulin-like growth factor-I, insulin-like growth factor-II and insulin-like growth factor binding protein-3 secretion by a human lung cancer cell line in vitro

The aim of our study was to evaluate the effect of alpha-interferon (alpha-IFN) on cell growth and on the different IGF system components in a human non-small cell lung cancer line (Calu-6) in vitro. Our results confirm the release of IGF-I and IGF-II by these cells. The amount of IGF-II in conditioned media (10.25 +/- 3.95 nM/10(6) cells, mean +/- SE) was more than 10-fold higher than that of IGF-I. alpha-IFN treatment reduced IGF-II levels in the media, with a maximal effect between 1 and 10 U/ml (delta% of control: -31 and -55%, respectively, p < 0.05). IGF-I was significantly reduced at 0.5 U/ml (p < 0.01). No difference, however, was observed in IGF mRNA expression between untreated and alpha-IFN treated cells. An increase in IGF-I and IGF-II intracellular levels in alpha-IFN treated cultures was observed, suggesting that alpha-IFN can regulate the transfer of these peptides into the cells. Furthermore, IGF type-I and particularly type-lI receptor expression was increased after alpha-IFN treatment. IGFBP-3 was detected only in trace amounts in the conditioned media; however, it showed an increase after alpha-IFN treatment (+110% at 1 U/ml). IGFBP-3 mRNA expression showed a slight increase after treatment with 1 and 10 U/ml. alpha-IFN (1-10 U/ml) reduced the stimulatory effect of IGF-I on cell replication (p < 0.01), inhibited (p < 0.01) cell replication in untreated and in fetal calf serum (FCS)-stimulated cells, and increased apoptosis in Calu-6 cells. Our data suggest that alpha-IFN may exert its effects at the cellular level in part through modification of the local IGF system.

Inhibition of infection and replication of human herpesvirus 8 in microvascular endothelial cells by alpha interferon and phosphonoformic acid

Infection of endothelial cells with human herpesvirus 8 (HHV-8) is an essential event in the development of Kaposi's sarcoma. When primary microvascular endothelial cells (MECs) were infected with HHV-8 at a low multiplicity of infection, considerable latent replication of HHV-8 occurred, leading to a time-dependent increase in the percentage of virus-infected cells that was accompanied by cellular spindling and growth to a high density with loss of contact inhibition. Only a low percentage of MECs supported lytic replication of HHV-8 and produced infectious virus. Phosphonoformic acid blocked production of infectious virus but did not inhibit the rapid expansion of latently infected MECs. Pretreatment of MECs with alpha interferon (IFN-alpha) prior to infection effectively reduced HHV-8 viral gene expression, latent replication, and production of infectious virus. High levels of the double-stranded RNA activated protein kinase (PKR) were expressed in HHV-8-infected cells, and incubation with IFN-alpha increased PKR expression more in virus-infected cells than in uninfected cells. MECs that were immortalized with simian virus 40 large-T antigen differed from nonimmortalized MECs in their response to infection with HHV-8 and demonstrated that cells with elevated levels of expression of antiviral transcripts expressed viral transcripts at reduced levels. These studies demonstrate that MECs respond to HHV-8 with enhanced expression of cellular antiviral genes and that augmentation of innate antiviral defenses with IFN-alpha is a more effective strategy than inhibition of viral lytic replication to protect MECs from infection with HHV-8 and to restrict proliferation of virus-infected MECs.

Monocytes Stimulated with Group B Streptococci or Interferons Release Tumour Necrosis Factor-Related Apoptosis-Inducing Ligand

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a cytotoxic member of the TNF family. Some reports have shown that TRAIL is released from cells in a soluble form. In this work, we have investigated the mechanism of release of TRAIL from monocytes. First, we show that whole gram-positive, gram-negative and mycoplasmal bacteria as well as lipopolysaccharide (LPS), interferon-alpha (IFN-alpha), -beta and -gamma all induced upregulation of TRAIL on the surface of human monocytes. Next, we show that IFN-alpha, -beta and -gamma all induced a dose-dependent release of TRAIL, giving significant amounts of soluble TRAIL after 2 days. Of the bacteria, only the Group B streptococcus COH-1 (GBS) induced release of TRAIL and concomittantly induced IFN-alpha. Monocytes stimulated with GBS or IFN-alpha also showed extensive cell death. When monocyte apoptosis was prevented by interleukin-1, GM-CSF, LPS or the caspase inhibitor zVADfmk, the IFN-alpha-induced release of TRAIL was reduced, whereas agents inducing necrosis caused increased release of TRAIL. LPS also prevented release of TRAIL from GBS-stimulated monocytes. The release of TRAIL from IFN-alpha-stimulated monocytes was reduced by inhibitors of both cysteine and metalloproteases. We conclude that bacteria and IFN induce upregulation of membrane TRAIL and that release of TRAIL is associated with cell death.

SOCS1 [corrected] inhibits HPV-E7-mediated transformation by inducing degradation of E7 protein

Human papilloma viruses (HPVs) are small double-stranded DNA viruses that infect mucosal and cutaneous epithelium and induce cervical cancer. It has been shown that interferon (IFN)gamma suppresses proliferation of HPV-infected cells by suppressing expression of HPV E7. Here, we found that IFNgamma induces not only suppression of E7 transcription but also proteasome-dependent degradation. Suppressor of cytokine signaling-1 (SOCS1)/JAB, a suppressor of cytokine signaling, is known to be induced by IFNgamma, and functions as an antioncogene against various hematopoietic oncogenic proteins. SOCS1 contains the SOCS-box, which is shown to recruit ubiquitin transferase to the molecules that interact with SOCS1. We found that SOCS1 interacted with HPV E7 protein and induced ubiquitination and degradation of E7 in a SOCS-box-dependent manner. SOCS1 overexpression also increased Rb protein levels and suppressed proliferation of cervical cancer cell lines infected with HPV. Moreover, E7 protein levels were higher and Rb protein levels were lower in SOCS1-deficient fibroblasts infected with retrovirus vector carrying E7 gene than in wild-type fibroblasts. E7 induced anchorage-independent growth in SOCS1-deficient fibroblasts, but not in wild-type cells. These data suggested that SOCS1 plays an important role in regulating the levels of E7 protein and their transforming potential, and could be a new therapeutic tool for HPV-mediated tumors.

IFN-alpha sensitizes human umbilical vein endothelial cells to apoptosis induced by double-stranded RNA

The ability of endothelial cells to mount an efficient antiviral response is important in restricting viral dissemination and eliminating viral infection from the endothelium and surrounding tissues. We demonstrate that dsRNA, a molecular signature of viral infection, induced apoptosis in HUVEC, and priming with IFN-alpha shortened the time between when dsRNA was encountered and when apoptosis was initiated. IFN-alpha priming induced higher levels of mRNA for dsRNA-activated protein kinase, 2'5'-oligoadenylate synthetase, and Toll-like receptor 3, transcripts that encode dsRNA-responsive proteins. dsRNA induced activation of dsRNA-activated protein kinase and nuclear translocation of transcription factors RelA and IFN regulatory factor-3 in IFN-alpha-primed HUVECs before the activation of intrinsic and extrinsic apoptotic pathways. These changes did not occur in the absence of dsRNA, and apoptosis resulting from incubation with dsRNA occurred much later when cells were not primed with IFN-alpha. The entire population of IFN-alpha-primed HUVECs underwent nuclear translocation of RelA and IFN regulatory factor-3 in response to dsRNA, whereas less than one-half of the population responded with apoptosis. When IFN-alpha-primed HUVECs were coincubated with dsRNA and proteasome inhibitors, all HUVECs were rendered susceptible to dsRNA-induced apoptosis. These studies provide evidence that many endothelial cells that are alerted to the risk of infection by IFN-alpha would undergo apoptosis sooner in response to dsRNA than non-IFN-alpha-primed cells, and this would enhance the likelihood of eliminating infected cells prior to the production of progeny virions.

Up-regulation of reactive oxygen species (ROS) and resistance to Fas-mediated apoptosis in the C33A cervical cancer cell line transfected with IL-18 receptor

Cervical cancer cells were transfected with a newly discovered interleukin (IL)-18 receptor to investigate the effect of endogenous IL-18 on the regulation of immune-related factors such as Fas (CD95/Apo-1)/Fas ligand and intercellular adhesion molecules. Transfection of the IL-18 receptor selectively induced a slight enhancement of the Fas via the up-regulation of intracellular reactive oxygen species and IL-18 in cervical carcinoma C33A cells, whereas there were no effects on the expression of p53, intercellular adhesion molecules-1 and Fas ligand. Neither IL-18 receptor transfection nor recombinant IL-18 enhanced interferon-γ production in C33A cells. Thus, IL-18 receptor transfection induced IL-18 expression and enhanced intracellular reactive oxygen species and Fas expression in C33A cells in an interferon-γ-independent pathway. However, treatment with agonistic anti-Fas antibody did not induce the apoptosis of C33A/IL-18 receptor transfectants, suggesting that either reactive oxygen species play a key role in resisting the Fas-induced apoptosis of C33A cells, or Fas was not functional. These results show that C33A/IL-18 receptor cells are resistant to the apoptosis and thus can survive against the immune surveillance and activated immune cells. Our results thus suggest that IL-18 and IL-18 receptor, together, may play a role in immunoregulation or in inflammation by augmenting the levels of IL-18 and reactive oxygen species in C33A cells.

Inhibition of angiogenesis as a therapeutic strategy against brain tumors

Multidisciplinary treatment strategies for patients with malignant brain tumors have resulted in only small gains in terms of prognosis in spite of the use of aggressive therapy. There is a growing realization that a paradigm shift is needed in the conceptual approaches to glioma therapy. Such approaches will rely on identification and modification of key cellular targets that define the biological behavior of these tumors. Among the targets for such treatment approaches, tumor angiogenesis has captured the attention of not only the medical field but also of the lay public because of its conceptual departure from traditional methods of cancer therapy. Angiogenesis and vascular proliferation are particularly important in the growth and progression of malignant gliomas and are used as indicators of the degree of malignancy. Recent studies have helped us gain a better understanding of the molecular mediators of this process. It is now evident that after the initial formation of malignancy the continued growth of a glioma is critically dependent on its angiogenic potential. Hence, several approaches to control angiogenesis are being developed and tested. Preliminary results from clinical studies have shown that angiogenesis inhibition is a valid approach as a therapeutic strategy against gliomas but it is also becoming evident that inhibition of individual modulators of this process may not yield the expected impact on prognosis. To fully realize the potential of antiangiogenic therapy, a deeper understanding of the interplay between the tumor vasculature and its environment is needed. Angiogenesis inhibitors have made the transition from preclinical studies to the clinical arena; it remains for ongoing human trials of such agents to fully explore the feasibility and efficacy of these agents in order to exploit the potential of this approach.

Interferon-gamma induces p11 gene and protein expression in human epithelial cells through interferon-gamma-activated sequences in the p11 promoter

The effect of interferon (IFN)-gamma on p11 expression was studied in two human epithelial cell lines (BEAS-2B and HeLa). Treatment with IFN-gamma resulted in increased steady-state levels of p11 mRNA and protein expression, with a time-dependent and dose-dependent effect. Transient transfection experiments of a reporter gene construct containing 1498 bp of the 5'-flanking region of the p11 promoter demonstrated that IFN-gamma induced p11 gene expression at the transcriptional level. These effects were inhibited at the promoter and protein levels by a specific JAK-2 kinase inhibitor, AG-490. Functional analysis of the p11 promoter indicates that two gamma-activated sequence elements (GAS) located at positions 1219 and 1090 are important for the induction of the p11 promoter by IFN-gamma. Transfection of mutated reporter constructs demonstrated that the mutation at the GAS-2 site (1090) inhibited the p11 promoter activity, with a reduction of about approximately 73% and mutation at the GAS-3 site (1219) eliminated about 26% of the p11 promoter activity. A STAT1 dominant negative mutant vector at Tyr-701 (JAK kinase phosphorylation site) blocked the effect of IFN-gamma on the p11 promoter activity. IFN-gamma induced a rapid tyrosine phosphorylation and nuclear translocation of STAT1 protein, which is involved in the binding to the GAS-2 site in the p11 promoter by EMSA analysis. These data suggest that IFN-gamma-induced p11 expression is mediated through the binding of STAT1 to GAS sites in the p11 promoter. Inhibition of p11 expression by inhibitory antisense RNAs (iRNA) treatment resulted in enhanced IFN-gamma and calcium ionophore-stimulated arachidonic acid release suggesting that at least in part IFN-gamma-stimulated p11 expression may serve a counterregulatory role.

Interferon-α-like biological activity in human seminal plasma, follicular fluid, embryo culture medium, amniotic fluid and fetal blood

Interferons (IFNs) are a group of cytokines exhibiting antiviral, antiproliferative and immunoregulatory properties. The principal stimulus for the synthesis of IFNs is the presence of viral double-stranded RNA, although rare examples of constitutive synthesis have also been described. The aim of the present study was to determine IFN-α-like biological activity in the seminal plasma, follicular and amniotic fluid, embryo culture medium, and fetal blood obtained from patients without apparent viral or bacterial infections. Interferon-α-like biological activity was determined by a standard cytopathic effect inhibition bioassay. The study included two groups of patients. The first group consisted of 30 married couples participating in the programme for assisted reproduction and the second group consisted of 23 patients scheduled for prenatal diagnosis (15 for amniocentesis and eight for cordocentesis). The seminal plasma of infertile men (asthenozoospermia, oligoasthenozoospermia) contained a high titre of IFN-α-like antiviral activity. Asthenozoospermia was diagnosed in men with a normal sperm concentration but less than 50% progressively motile sperm and oligoasthenozoospermia was diagnosed in men with a sperm count less than 1 × 106 mL−1. Despite slightly higher antiviral titres in the seminal plasma obtained from asthenozoospermic patients, no clear association between IFN-α-like biological activity and sperm concentration was found. Interferon-α-like biological activity was found in all samples of follicular and amniotic fluid and in fetal blood of patients with intrauterine growth retardation and trisomy 18. Antiviral titres from seminal plasma and follicular fluids were significantly higher compared with amniotic fluids and fetal blood. Embryo culture medium did not contain IFN-α-like biological activity. Our results demonstrate that IFN-α-like activity in biological fluids is relevant for reproduction, even in the absence of infection.

Treatment of canine parvoviral enteritis with interferon-omega in a placebo-controlled challenge trial

Canine parvoviral enteritis continues to cause significant morbidity and mortality in dogs worldwide, and efficacious antiviral therapies are lacking. The present trial was aimed at evaluating the therapeutic efficacy of a recombinant feline interferon (type omega) preparation in the treatment of parvoviral enteritis in dogs. A double-blind, placebo-controlled challenge trial was performed in beagle pups (8-9 weeks); clinical signs, body weight, hematologic parameters, and mortality were monitored for a period of 14 days after challenge. Fourteen animals were inoculated with virulent canine parvovirus; 10 animals that developed clinical signs thereby meeting the inclusion criteria were admitted to the treatment phase in two randomly selected groups (placebo and IFN) of equal size. The IFN group received daily intravenous injections of rFeIFN-omega (2.5 MU/kg) for three consecutive days. The placebo group received daily injections of saline without IFN. Both groups of animals received individual supportive treatment consisting of adjusted diet and electrolyte solution. All five dogs in the placebo group developed fulminating enteritis with typical clinical signs and died within 10 days post-inoculation (or 6 days post-treatment). In the IFN-treated group, one animal died on day 2 after the treatment was started, whereas the other four dogs survived the challenge and gradually recovered. Our data confirm that the rFeIFN-omega can exert a significant therapeutic effect on dogs with parvoviral enteritis by improving clinical signs and reducing mortality.

FcgammaRIII expression on cultured human keratinocytes and upregulation by interferon-gamma

Keratinocytes of human epidermis are actively involved in inflammatory and autoimmune reactions of the skin and interact with resident or infiltrating immunocompetent cells via cytokines, chemokines, and intercellular adhesion mechanisms. Most immunocompetent cells have been reported to express Fcgamma receptors (FcgammaR), which are important for immunoregulatory functions. In this study we investigate FcgammaRIII expression on cultured human keratinocytes and upregulation by interferon-gamma. By real-time polymerase chain reaction, we show basal mRNA expression of both subclasses FcgammaRIIIA and FcgammaRIIIB, but after interferon-gamma treatment mRNA of FcgammaRIIIA and FcgammaRIIIB is increased 4.4 and 6.5 times, respectively. FcgammaRIII protein expression and its increase after interferon-gamma treatment were shown on cultured human keratinocytes by indirect immunofluorescence. In immunoblotting experiments, a bonified anti-CD16 antibody revealed reactivity to a polypeptide of 50-65 kDa on lysates of treated and untreated keratinocytes. In summary, we demonstrate expression of mRNA specific for the FcgammaRIIIA and FcgammaRIIIB subclasses and their upregulation by interferon-gamma on human keratinocytes in vitro, and confirm FcgammaRIII protein expression by indirect immunofluorescence and by immunoblotting experiments.

Characterization of monoclonal antibodies against GRIM-19, a novel IFN-beta and retinoic acid-activated regulator of cell death

A combination of interferon-beta (IFN-beta) and all-trans retinoic acid (IFN/RA) induces tumor cell apoptosis via some unknown mechanisms. Apoptosis is a gene-directed process that limits the proliferation of undesired cells. Several genes are required to regulate cell death in the higher-order animals. Earlier, we employed a gene expression knockout technique to isolate cell death-related genes. A novel gene, the gene associated with retinoid-interferon-induced mortality-19 (GRIM-19), was found to be essential for tumor cell death induced by IFN/RA. Here, we describe the development and characterization of three monoclonal antibodies (mAbs) against GRIM-19. GRIM-19 is present in the nucleus and cytoplasm. Its expression is induced by the IFN/RA combination. We also show that GRIM-19 inhibits the cell-transforming property of viral oncogenic protein viral IFN regulatory factor-1 (vIRF-1) via a physical interaction. mAbs developed in this study should be useful for studying the other physiologic roles of GRIM-19 and serve as a potent tool for studying tumor responses to IFN/RA therapy.

2'-5' Oligoadenylate synthetase plays a critical role in interferon-gamma inhibition of respiratory syncytial virus infection of human epithelial cells

Respiratory syncytial virus (RSV), associated with bronchiolitis and asthma, is resistant to the antiviral effects of type-I interferons (IFN), but not IFN-gamma. However, the antiviral mechanism of IFN-gamma action against RSV infection is unknown. The molecular mechanism of IFN-gamma-induced antiviral activity was examined in this study using human epithelial cell lines HEp-2 and A549. Exposure of these cells to 100-1000 units/ml of IFN-gamma, either before or after RSV infection, results in a significant decrease in RSV infection. After 1 h of exposure, IFN-gamma induces protein expression of IFN regulatory factor-1 (IRF-1) but not IRF-2, double-stranded RNA-activated protein kinase, and inducible nitric-oxide synthase in these cells. The mRNA for IRF-1, p40, and p69 isoforms of 2'-5' oligoadenylate synthetase (2-5 AS) are detectable, respectively, at 1 and 4 h of IFN-gamma exposure. Studies using cycloheximide and antisense oligonucleotides to IRF-1 indicate a direct role of IRF-1 in activating 2-5 AS. Cells transfected with 2-5 AS antisense oligonucleotides inhibit the antiviral effect of IFN-gamma. A stable cell line of HEp-2 overexpressing RNase L inhibitor, RLI-14, which exhibits an IFN-gamma-induced gene expression pattern similar to that of the parent cell line, shows a significant reduction in RNase L activity and IFN-gamma-mediated antiviral effect, compared with HEp-2 cells. These results provide direct evidence of the involvement of 2-5 AS in IFN-gamma-mediated antiviral activity in these cells.

IFN-stimulated gene 15 is synergistically activated through interactions between the myelocyte/lymphocyte-specific transcription factors, PU.1, IFN regulatory factor-8/IFN consensus sequence binding protein, and IFN regulatory factor-4: characterization of a new subtype of IFN-stimulated response element

Type I IFNs cause the induction of a subset of genes termed IFN-stimulated genes (ISGs), which harbor a specific DNA element, IFN-stimulated response element (ISRE). This ISRE confers the responsiveness to the IFN signal through the binding of a family of transcription factors designated IFN regulatory factors (IRFs). Some IRFs can bind to the DNA alone, such as IRF-1, which elicits transcriptional activation, or IRF-2, which leads to transcriptional repression. In addition, these factors associate with IRF-8/IFN consensus sequence binding protein (ICSBP), an immune cell-restricted IRF, and the assembled heterocomplexes lead to synergistic repression of ISRE elements. ISG15 is a prototype ISG that contains a well-characterized ISRE. Here we show that PU.1, an ETS member essential for myeloid/lymphoid cell differentiation, forms heterocomplexes with the immune-restricted IRFs, IRF-8\/ICSBP and IRF-4, which lead to transcriptional activation of ISG15. These data allowed the characterization of a subset of ISREs designated ETS/IRF response element (EIRE), which are differentially regulated in immune cells. EIREs are unique in their ability to recruit different factors to an assembled enhanceosomes. In nonimmune cells the factors will mainly include IRF members, while cell type-restricted factors, such as PU.1, IRF-8\/ICSBP, and IRF-4, will be recruited in immune cells. IRF heterocomplex formation leads to transcriptional repression, and conversely, PU.1/IRFs heterocomplex formation leads to transcriptional activation. The fact that IRF-8\/ICSBP is an IFN-gamma-induced factor explains why some of the EIREs are also induced by type II IFN. Our results lay the molecular basis for the unique regulation of ISGs, harboring EIRE, in immune cells.

Preferential binding sites for interferon regulatory factors 3 and 7 involved in interferon-A gene transcription

Transcription of the murine interferon-A4 (IFN-A4) gene is mediated by a virus responsive element (VRE-A4) located in the promoter proximal [-120 to -43] region. VRE-A4 contains four DNA modules (A to D) which cooperate for maximal IFN-A4 activation following virus infection. The differential expression between the highly expressed IFN-A4 and the weakly inducible IFN-A11 gene promoters is essentially due to point mutations within the C and D modules of the virus-responsive element VRE-A11. We now demonstrate that in murine L929 and human 293 cells, transcription factors IRF-3 and IRF-7, which are potent activators of virus-induced type I IFN transcription, differentially affect IFN-A4 and IFN-A11 promoter activities. Using electrophoretic mobility shift assays and DNase I footprinting data, our studies demonstrate that the AB modules correspond to a preferential site for IRF-7, whereas the C module is preferentially recognized by IRF-3. Furthermore, transfection of reporter constructs driven by four copies of different GAAANN hexameric motifs found within VRE-A4 indicates that the NN residues of these hexameric sequences define the preferential binding sites for IRF-3 or IRF-7. Together, these experiments clarify the molecular basis for differential expression of IFN-A genes following virus infection by delineating the sequence requirements for IRF association with the virus responsive elements of the IFN-A genes.

Efficacy of low-dose interferon with antiretroviral therapy in Kaposi's sarcoma: a randomized phase II AIDS clinical trials group study

We wished to evaluate the efficacy and safety of a low and an intermediate daily dose of interferon-alpha2b (IFN-alpha2b) with didanosine in patients with acquired immunodeficiency syndrome (AIDS)-associated Kaposi's sarcoma (KS). HIV-seropositive subjects with biopsy-confirmed cutaneous KS were randomized to receive either a low (1 million IU) or an intermediate (10 million IU) dose of IFN-alpha2b once daily with twice daily doses of didanosine. Treatment assignment was stratified by CD4 count. Response, toxicity, changes in CD4 counts, and survival were evaluated. Sixty-eight eligible subjects were accrued, 35 to low-dose and 33 to intermediate-dose IFN-alpha2b. The response rate was 40% in the low-dose group (95% CI, 24-58) and 55% in the intermediate-dose group (95% CI, 36-72) (p = 0.338). The median response duration was approximately 110 weeks in both groups. Intermediate-dose IFN induced grade 3/4 neutropenia more often (21% vs. 3%, p = 0.048) and grade 3/4 toxicity faster (p = 0.0231) and necessitated treatment discontinuation earlier for drug-related toxicities (p = 0.0416) than low-dose IFN. There were no significant differences in survival between the treatment groups. Baseline CD4 count was the only significant factor predicting response. Once-daily low-dose and intermediate-dose IFN-alpha2b induced similar response rates, which were achieved without optimal antiretroviral therapy. The slightly higher response rate in the intermediate-dose group was offset by its significantly poorer tolerance. These findings justify the use of lower, well-tolerated IFN doses for treatment of KS with currently used antiretroviral regimens.

Interferon-regulated pathways that control hepatitis B virus replication in transgenic mice

We previously showed that the intrahepatic induction of cytokines such as alpha/beta interferon (IFN-alpha/beta) and gamma interferon (IFN-gamma) inhibits hepatitis B virus (HBV) replication noncytopathically in the livers of transgenic mice. The intracellular pathway(s) responsible for this effect is still poorly understood. To identify interferon (IFN)-inducible intracellular genes that could play a role in our system, we crossed HBV transgenic mice with mice deficient in IFN regulatory factor 1 (IRF-1), the double-stranded RNA-activated protein kinase (PKR), or RNase L (RNase L) (IRF-1(-/-), PKR(-/-), or RNase L(-/-) mice, respectively), three well-characterized IFN-inducible genes that mediate antiviral activity. We showed that unmanipulated IRF-1(-/-) or PKR(-/-) transgenic mice replicate HBV in the liver at slightly higher levels than the respective controls, suggesting that both IRF-1 and PKR individually appear to mediate signals that modulate HBV replication under basal conditions. These same animals were responsive to the antiviral effects of the IFN-alpha/beta inducer poly(I-C) or recombinant murine IFN-gamma, suggesting that under these conditions, either the IRF-1 or the PKR genes can mediate the antiviral activity of the IFNs or other IFN-inducible genes mediate the antiviral effects. Finally, RNase L(-/-) transgenic mice were undistinguishable from controls under basal conditions and after poly(I-C) or IFN-gamma administration, suggesting that RNase L does not modulate HBV replication in this model.

Regression of tumors by IFN-alpha electroporation gene therapy and analysis of the responsible genes by cDNA array

The key to success with nonviral gene therapy as a treatment for cancer is to discover effective therapeutic genes and gene delivery methods and to understand how tumors are eradicated. We discovered that electroporation of IFN-alpha DNA into tumors in the SCCVII tumor-bearing mice led to tumor eradication in 50% of the mice and a more than two-fold increase in survival time when compared with controls (P = 0.0012). Analyses using cDNA array and Northern blot indicated that the genes responsible for the therapeutic effect of electro-IFN-alpha gene therapy included IRF-7, Granzyme A, Granzyme C, Gjb2, Krt14, Mig, IP-10 and MCP3. Because most of these genes have been known to either inhibit angiogenesis (Mig, IP-10), inhibit tumor growth (Gjb2, MCP3), kill tumor cells (Granzyme A and C), or induce expression of antitumor gene (IRF-7), they may become promising therapeutic gene candidates for a combination gene therapy approach to cancer treatment.

Interferon Beta secreted from human hair dermal papilla cells inhibits the growth of outer root sheath cells cultured in vitro

Hair growth is tightly regulated by the epithelial-mesenchymal interaction of hair follicle cells. To investigate the molecular interaction between epithelial and mesenchymal cells of the hair follicle, the outer root sheath (ORS) cells were cultured with the dermal papilla (DP)-conditioned medium. Using the techniques of differential display reverse transcription-polymerase chain reaction (DD RT-PCR) and Northern blot analysis, we identified that an interferon-inducible gene 6-16 is regulated in the ORS cells when cultured with the DP-conditioned medium. We further studied the effect of the DP-conditioned medium and found that interferon beta, a predominant interferon secreted by the fibroblasts, is expressed by the DP cells. Moreover, the anti-interferon beta neutralized DP-conditioned medium dramatically inhibited the 6-16 mRNA expression. Interferon beta or DP-conditioned medium suppressed the growth of the in vitro cultured ORS cells, suggesting that interferon beta secreted from the DP cells negatively regulates the growth of ORS cells. Together these results reveal the potential importance of the interferon beta as a negative regulator of hair growth.

The virus-induced factor VIF differentially recognizes the virus-responsive modules of the mouse IFNA4 gene promoter

Maximal activation of murine infection-A4 (IFNA4) gene transcription following viral infection requires the presence of four cooperating DNA sequences (denoted A to D), which make up the virus responsive element VRE-A4. The B, C, and D modules, when tandemized, form binding sites for the virus-induced factor (VIF), a multiprotein complex that is detected early after viral infection in the nuclei of mouse L929 cells. We now demonstrate that IFN regulatory factor-3 (IRF-3) is a component of VIF and that VIF is different from the previously identified virus-activated complexes containing IRF-3 and coactivators of transcription, such as CREB binding protein (CBP) or p300. We also show that the C module is critical for both IRF-3-mediated and virus-induced transcription of the murine IFNA4 gene. Consistently, DNase I footprinting experiments and EMSA performed with increasing amounts of recombinant GST-IRF-3(DBD) fusion proteins demonstrate that cooperativity between the modules facilitate the binding of IRF-3 and recruitment of transcription coactivators on the IFNA4 promoter. These results indicate that VIF differentially recognizes the virus-responsive modules of VRE-A4 and further actualize our previous model concerning the differential expression of murine IFNA genes.

Inhibition of 2'-5' oligoadenylate synthetase by divalent metal ions

OAS1 is the small form and OAS2 is the medium form of the human interferon-induced 2'-5' oligoadenylate synthetases. The p42 isoform of OAS1 and the p69 isoform of OAS2 have been expressed in insect cells and purified to give pure, highly active 2'-5' oligoadenylate synthetase. The catalysis of 2'-5' oligoadenylate synthesis is strictly dependent on double-stranded RNA and magnesium ions. We have examined the effect of a series of divalent metal ions: copper, iron and zinc ions strongly inhibited the enzymatic activity, cobalt and nickel ions were partly inhibitory whereas calcium and manganese ions were without effect. However, manganese ions can replace magnesium ions as activator. The inhibitory effect of zinc ions was characterised in detail. The inhibitory constants of Zn(2+) were estimated to be 0.10 mM for OAS1p42 and to 0.02 mM for OAS2p69. Cross-linking experiments showed that zinc ions can control the oligomerisation by enhancing the formation of tetrameric forms of OAS1p42

Noncytolytic control of viral infections by the innate and adaptive immune response

This review describes the contribution of noncytolytic mechanisms to the control of viral infections with a particular emphasis on the role of cytokines in these processes. It has long been known that most cell types in the body respond to an incoming viral infection by rapidly secreting antiviral cytokines such as interferon alpha/beta (IFN-alpha/beta). After binding to specific receptors on the surface of infected cells, IFN-alpha/beta has the potential to trigger the activation of multiple noncytolytic intracellular antiviral pathways that can target many steps in the viral life cycle, thereby limiting the amplification and spread of the virus and attenuating the infection. Clearance of established viral infections, however, requires additional functions of the immune response. The accepted dogma is that complete clearance of intracellular viruses by the immune response depends on the destruction of infected cells by the effector cells of the innate and adaptive immune system [natural killer (NK) cells and cytotoxic T cells (CTLs)]. This notion, however, has been recently challenged by experimental evidence showing that much of the antiviral potential of these cells reflects their ability to produce antiviral cytokines such as IFN-gamma and tumor necrosis factor (TNF)-alpha at the site of the infection. Indeed, these cytokines can purge viruses from infected cells noncytopathically as long as the cell is able to activate antiviral mechanisms and the virus is sensitive to them. Importantly, the same cytokines also control viral infections indirectly, by modulating the induction, amplification, recruitment, and effector functions of the immune response and by upregulating antigen processing and display of viral epitopes at the surface of infected cells. In keeping with these concepts, it is not surprising that a number of viruses encode proteins that have the potential to inhibit the antiviral activity of cytokines.

IFN-gamma inhibits lipopolysaccharide-induced interleukin-1 beta in primary murine macrophages via a Stat1-dependent pathway

Interleukin-1 (IL-1) plays an important role in host defenses against microbial pathogens. Excessive production of this cytokine, however, may be responsible in part for the lethality observed during sepsis. Our studies show that interferon-gamma (IFN-gamma) downregulates lipopolysaccharide (LPS)-induced interleukin-1beta (IL-1beta) transcription in primary macrophages. This phenomenon does not occur in splenocytes or bone marrow-derived macrophages from signal transducer and activator of transcription (Stat1)-deficient mice, suggesting that Stat1, a transcription factor involved in IFN signaling, plays a critical role in this process. Moreover, nitric oxide (NO) was also involved in the downregulation of LPS-induced IL-1 by IFN, as addition of the inducible nitric oxide synthase (iNOS) inhibitor L-N(6)-(1-iminoethyl)lysine (NIL) negated the effect. Kinetic analysis of IL-1 and IFN levels in LPS-treated mice in vivo suggests that IFN-mediated inhibition of IL-1 might be an important negative feedback mechanism for limiting IL-1 generation in vivo.