Induction of monocytic differentiation and NF-kappa B-like activities by human immunodeficiency virus 1 infection of myelomonoblastic cells.

The effects of human immunodeficiency virus 1 (HIV-1) infection on cellular differentiation and NF-kappa B DNA binding activity have been investigated in a new model of myeloid differentiation. PLB-985 cells represent a bipotential myelomonoblastic cell population capable of either granulocytic or monocytic differentiation after induction with appropriate inducers. By virtue of the presence of CD4 on the cell surface, PLB-985 cells were chronically infected with HIV-1 strain IIIB. PLB-IIIB cells clearly possessed a more monocytic phenotype than the parental myeloblasts, as determined by differential staining, increased expression of the myeloid-specific surface markers, and transcription of the c-fms proto-oncogene. NF-kappa B binding activity was inducible by tumor necrosis factor and phorbol myristate acetate in PLB-985. However, in PLB-IIIB cells, constitutive expression of a novel NF-kappa B complex was detected, composed of proteins ranging between 70 and 110 kD. These proteins interacted specifically with the symmetric NF-kappa B site from the interferon beta (IFN-beta) promoter. Mutations affecting the 5' guanine residues of the kappa B site were unable to compete for these NF-kappa B-related proteins. Inducibility of endogenous IFN-beta and IFN-alpha RNA was also increased in PLB-IIIB cells. These studies indicate that HIV-1 infection of myelomonoblastic cells may select for a more mature monocytic phenotype and that unique subunit associations of NF-kappa B DNA binding proteins may contribute to differential NF-kappa B-mediated gene expression.

Innovative therapy, monoclonal antibodies, and beyond: Highlights from the eighth annual meeting.

The eighth annual conference of "Innovative therapy, monoclonal antibodies, and beyond" was held in Milan on Jan. 26, 2018, and hosted by Fondazione IRCCS-Istituto Nazionale dei Tumori (Fondazione IRCCS INT). The conference was divided into two main scientific sessions, of i) pre-clinical assays and novel biotargets, and ii) clinical translation, as well as a third session of presentations from young investigators, which focused on recent achievements within Fondazione IRCCS INT on immunotherapy and targeted therapies. Presentations in the first session addressed the issue of cancer immunotherapy activity with respect to tumor heterogeneity, with key topics addressing: 1) tumor heterogeneity and targeted therapy, with the definition of the evolutionary Index as an indicator of tumor heterogeneity in both space and time; 2) the analysis of cancer evolution, with the introduction of the TRACERx Consortium-a multi-million pound UK research project focused on non-small cell lung cancer (NSCLC); 3) the use of anti-estrogen agents to boost immune recognition of breast cancer cells; and 4) the high degree of functional plasticity within the NK cell repertoire, including the expansion of adaptive NK cells following viral challenges. The second session addressed: 1) the effectiveness of radiotherapy to enhance the proportion of patients responsive to immune-checkpoint blockers (ICBs); 2) the use of MDSC scores in selecting melanoma patients with high probability to be responsive to ICBs; and 3) the relevance of the gut microbiome as a predictive factor, and the potential of its perturbation in increasing the immune response rate to ICBs. Overall, a picture emerged of tumor heterogeneity as the main limitation that impairs the effectiveness of anti-cancer therapies. Thus, the choice of a specific therapy based on reproducible and selective predictive biomarkers is an urgent unmet clinical need that should be addressed in order to increase the proportion of long-term responding patients and to improve the sustainability of novel drugs.

Manipulation of the nuclear factor-kappaB pathway and the innate immune response by viruses.

Viral and microbial constituents contain specific motifs or pathogen-associated molecular patterns (PAMPs) that are recognized by cell surface- and endosome-associated Toll-like receptors (TLRs). In addition, intracellular viral double-stranded RNA is detected by two recently characterized DExD/H box RNA helicases, RIG-I and Mda-5. Both TLR-dependent and -independent pathways engage the IkappaB kinase (IKK) complex and related kinases TBK-1 and IKKvarepsilon. Activation of the nuclear factor kappaB (NF-kappaB) and interferon regulatory factor (IRF) transcription factor pathways are essential immediate early steps of immune activation; as a result, both pathways represent prime candidates for viral interference. Many viruses have developed strategies to manipulate NF-kappaB signaling through the use of multifunctional viral proteins that target the host innate immune response pathways. This review discusses three rapidly evolving areas of research on viral pathogenesis: the recognition and signaling in response to virus infection through TLR-dependent and -independent mechanisms, the involvement of NF-kappaB in the host innate immune response and the multitude of strategies used by different viruses to short circuit the NF-kappaB pathway.

Oncolytic activity of vesicular stomatitis virus in primary adult T-cell leukemia.

Treatments for hematological malignancies have improved considerably over the past decade, but the growing therapeutic arsenal has not benefited adult T-cell leukemia (ATL) patients. Oncolytic viruses such as vesicular stomatitis virus (VSV) have recently emerged as a potential treatment of solid tumors and leukemias in vitro and in vivo. In the current study, we investigated the ability of VSV to lyse primary human T-lymphotropic virus type 1 (HTLV-1)-infected T-lymphocytes from patients with ATL. Ex vivo primary ATL cells were permissive for VSV and underwent rapid oncolysis in a time-dependent manner. Importantly, VSV infection showed neither viral replication nor oncolysis in HTLV-1-infected, nonleukemic cells from patients with HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), and in naive CD4(+) T-lymphocytes from normal individuals or in ex vivo cell samples from patients with chronic lymphocytic leukemia (CLL). Interestingly, activation of primary CD4(+) T-lymphocytes with anti-CD3/CD28 monoclonal antibody, and specifically with anti-CD3, was sufficient to induce limited viral replication and oncolysis. However, at a similar level of T-cell activation, VSV replication was increased fourfold in ATL cells compared to activated CD4(+) T-lymphocytes, emphasizing the concept that VSV targets genetic defects unique to tumor cells to facilitate its replication. In conclusion, our findings provide the first essential information for the development of a VSV-based treatment for ATL.

Infection of peripheral blood mononuclear cells by herpes simplex and Epstein-Barr viruses. Differential induction of interleukin 6 and tumor necrosis factor-alpha.

Infection by herpesviruses can result in profound immunosuppressive or immunomodulatory effects. However, no significant information is available on the effect of such infections on the production of immunoregulatory cytokines. We studied the kinetics of production of two monocyte-derived cytokines, interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF alpha), induced by Epstein-Barr virus (EBV) and herpes simplex virus type 1 (HSV-1) in peripheral blood mononuclear cell cultures and in fractionated cell populations. We observed that, when compared to HSV-1, EBV is a stronger inducer of IL-6. In EBV-infected cultures, IL-6 protein was detected at day 1 postinfection and gradually increased with time. In contrast, lower amounts of IL-6 were detected 5 d postinfection in HSV-1-infected cultures. HSV-1-infected cultures secreted significant amounts of TNF alpha protein after 5 d of culture and reached a maximal level of production at day 7, whereas EBV inhibited TNF alpha production. In fractionated cell populations, monocytic cells were found to be the main source of IL-6 synthesis after EBV or HSV-1 infection. However, TNF alpha synthesis in HSV-1-infected cultures was from both B and monocytic cells. By using the polymerase chain reaction technique we show that, after infection by these two herpesviruses, differences in cytokine gene products are also observed at the transcriptional level. These observations demonstrate that EBV and HSV-1 exert differential effects on IL-6 and TNF alpha gene transcription and on the resulting protein secretion in human mononuclear blood cells.

Structural and functional analysis of interferon regulatory factor 3: localization of the transactivation and autoinhibitory domains.

The interferon regulatory factor 3 (IRF-3) gene encodes a 55-kDa protein which is expressed constitutively in all tissues. In unstimulated cells, IRF-3 is present in an inactive cytoplasmic form; following Sendai virus infection, IRF-3 is posttranslationally modified by protein phosphorylation at multiple serine and threonine residues located in the carboxy terminus. Virus-induced phosphorylation of IRF-3 leads to cytoplasmic to nuclear translocation of phosphorylated IRF-3, association with the transcriptional coactivator CBP/p300, and stimulation of DNA binding and transcriptional activities of virus-inducible genes. Using yeast and mammalian one-hybrid analysis, we now demonstrate that an extended, atypical transactivation domain is located in the C terminus of IRF-3 between amino acids (aa) 134 and 394. We also show that the C-terminal domain of IRF-3 located between aa 380 and 427 participates in the autoinhibition of IRF-3 activity via an intramolecular association with the N-terminal region between aa 98 and 240. After Sendai virus infection, an intermolecular association between IRF-3 proteins is detected, demonstrating a virus-dependent formation of IRF-3 homodimers; this interaction is also observed in the absence of virus infection with a constitutively activated form of IRF-3. Substitution of the C-terminal Ser-Thr phosphorylation sites with the phosphomimetic Asp in the region ISNSHPLSLTSDQ between amino acids 395 and 407 [IRF-3(5D)], but not the adjacent S385 and S386 residues, generates a constitutively activated DNA binding form of IRF-3. In contrast, substitution of S385 and S386 with either Ala or Asp inhibits both DNA binding and transactivation activities of the IRF-3(5D) protein. These studies thus define the transactivation domain of IRF-3, two domains that participate in the autoinhibition of IRF-3 activity, and the regulatory phosphorylation sites controlling IRF-3 dimer formation, DNA binding activity, and association with the CBP/p300 coactivator.

Transient expression of the beta interferon promoter in human cells.

A human transient expression assay was used to examine the inducible transcriptional activation of beta interferon (IFN-beta) and IFN-alpha 1 promoters in a homologous cellular environment. Use of 293 cells, an adenovirus DNA-transformed human embryonic kidney cell line, permitted Sendai virus-inducible expression of IFN-beta-CAT hybrid gene. Introduction of the simian virus 40 (SV40) enhancer 5' or 3' to the IFN-CAT gene increased basal (uninduced) levels of chloramphenicol acetyltransferase (CAT) activity; in one construct the SV40 enhancer--IFN-beta regulatory region combination increased the induced CAT activity 50- to 100-fold, suggesting that this may be a generally useful inducible enhancer-promoter combination. No expression from the IFN-alpha-CAT hybrid gene was detected in 293 cells, indicating that human epithelioid cells lack a factor required for expression of the IFN-alpha promoter. However, when the IFN-alpha regulatory region was combined with the SV40 enhancer, a low level of inducible CAT activity was detected in the human transient system.

trans activation of type 1 interferon promoters by simian virus 40 T antigen.

A human transient expression system was used to measure the influence of simian virus 40 T antigen and adenovirus E1a proteins on the activation of alpha interferon subtype 1 (IFN-alpha 1) and IFN-beta promoters linked to the reporter chloramphenicol acetyltransferase gene. Large T-antigen production, amplified by expression plasmid replication in transfected 293 cells, was able to trans activate the IFN-beta promoter 5- to 10-fold, increasing both the constitutive and Sendai virus-induced levels of expression. Surprisingly, the previously quiescent transfected IFN-alpha 1 promoter in T-antigen-expressing cells displayed a level of inducibility similar to IFN-beta. The endogenous IFN-alpha 1 gene was also inducible to a limited extent in cells expressing T antigen. A truncated IFN-beta promoter deleted to position -37 relative to the CAP site was neither inducible nor trans activated by T antigen, suggesting that sequences required for efficient induction were also needed for trans activation. Since 293 cells express adenoviral E1a proteins, experiments were also performed in HeLa cells to assess the relative contribution of T antigen and E1a proteins to IFN trans activation. In HeLa cells, T-antigen coexpression increased the constitutive level of IFN-beta and IFN-alpha 1 promoter activity without augmenting relative inducibility. Coexpression of T antigen and E1a proteins did not have a cooperative effect on type 1 IFN expression.

Selective DNA binding and association with the CREB binding protein coactivator contribute to differential activation of alpha/beta interferon genes by interferon regulatory factors 3 and 7.

Recent studies implicate the interferon (IFN) regulatory factors (IRF) IRF-3 and IRF-7 as key activators of the alpha/beta IFN (IFN-alpha/beta) genes as well as the RANTES chemokine gene. Using coexpression analysis, the human IFNB, IFNA1, and RANTES promoters were stimulated by IRF-3 coexpression, whereas the IFNA4, IFNA7, and IFNA14 promoters were preferentially induced by IRF-7 only. Chimeric proteins containing combinations of different IRF-7 and IRF-3 domains were also tested, and the results provided evidence of distinct DNA binding properties of IRF-3 and IRF-7, as well as a preferential association of IRF-3 with the CREB binding protein (CBP) coactivator. Interestingly, some of these fusion proteins led to supraphysiological levels of IFN promoter activation. DNA binding site selection studies demonstrated that IRF-3 and IRF-7 bound to the 5'-GAAANNGAAANN-3' consensus motif found in many virus-inducible genes; however, a single nucleotide substitution in either of the GAAA half-site motifs eliminated IRF-3 binding and transactivation activity but did not affect IRF-7 interaction or transactivation activity. These studies demonstrate that IRF-3 possesses a restricted DNA binding site specificity and interacts with CBP, whereas IRF-7 has a broader DNA binding specificity that contributes to its capacity to stimulate delayed-type IFN gene expression. These results provide an explanation for the differential regulation of IFN-alpha/beta gene expression by IRF-3 and IRF-7 and suggest that these factors have complementary rather than redundant roles in the activation of the IFN-alpha/beta genes.

Identification by in vivo genomic footprinting of a transcriptional switch containing NF-kappaB and Sp1 that regulates the IkappaBalpha promoter.

In unstimulated cells, NF-kappaB transcription factors are retained in the cytoplasm by inhibitory IkappaB proteins. Upon stimulation by multiple inducers including cytokines or viruses, IkappaBalpha is rapidly phosphorylated and degraded, resulting in the release of NF-kappaB and the subsequent increase in NF-kappaB-regulated gene expression. IkappaBalpha gene expression is also regulated by an NF-kappaB autoregulatory mechanism, via NF-kappaB binding sites in the IkappaBalpha promoter. In previous studies, tetracycline-inducible expression of transdominant repressors of IkappaBalpha (TD-IkappaBalpha) progressively decreased endogenous IkappaBalpha protein levels. In the present study, we demonstrate that expression of TD-IkappaBalpha blocked phorbol myristate acetate-phytohemagglutinin or tumor necrosis factor alpha-induced IkappaBalpha gene transcription and abolished NF-kappaB DNA binding activity, due to the continued cytoplasmic sequestration of RelA(p65) by TD-IkappaBalpha. In vivo genomic footprinting revealed stimulus-responsive protein-DNA binding not only to the -63 to -53 kappaB1 site but also to the adjacent -44 to -36 Sp1 site of the IkappaBalpha promoter. In vivo protection of both sites was inhibited by tetracycline-inducible TD-IkappaBalpha expression. Prolonged NF-kappaB binding and a temporal switch in the composition of NF-kappaB complexes bound to the -63 to -53 kappaB1 site of the IkappaBalpha promoter were also observed; with time after induction, decreased levels of transcriptionally active p50-p65 and increased p50-c-Rel heterodimers were detected at the kappaB1 site. Mutation of either the kappaB1 site or the Sp1 site abolished transcription factor binding to the respective sites and the inducibility of the IkappaBalpha promoter in transient transfection studies. These observations provide the first in vivo characterization of a promoter proximal transcriptional switch involving NF-kappaB and Sp1 that is essential for autoregulation of the IkappaBalpha promoter.

Synergism between distinct enhanson domains in viral induction of the human beta interferon gene.

This study demonstrates distinct virus-inducible enhanson properties for three regions of the human beta interferon (IFN-beta) promoter; maximum virus inducibility required syngerism among all three enhansons. Expression of the IRF-1 transcription factor differentially increased the expression of plasmids containing (AAGTGA)4 or PRDIII (-94 to -78) motifs but was inefficient in the induction of the intact IFN-beta promoter. The human T-cell lymphotropic virus type I Tax protein was a strong positive activator of PRDII (-64 to -55)-containing plasmids but was also unable to stimulate the IFN-beta promoter. Induction of the intact IFN-beta promoter linked to a reporter plasmid was achieved in lymphoid and epithelioid cellular backgrounds by a triple transfection with IRF-1 and Tax expression plasmids or a combination of IRF-1 and phorbol ester, indicating that at least two trans-activating events and the association of two proteins on the promoter template are required for IFN-beta activation.

Virus-dependent phosphorylation of the IRF-3 transcription factor regulates nuclear translocation, transactivation potential, and proteasome-mediated degradation.

The interferon regulatory factors (IRF) consist of a growing family of related transcription proteins first identified as regulators of the alpha beta interferon (IFN-alpha/beta) gene promoters, as well as the interferon-stimulated response element (ISRE) of some IFN-stimulated genes. IRF-3 was originally identified as a member of the IRF family based on homology with other IRF family members and on binding to the ISRE of the ISG15 promoter. IRF-3 is expressed constitutively in a variety of tissues, and the relative levels of IRF-3 mRNA do not change in virus-infected or IFN-treated cells. In the present study, we demonstrate that following Sendai virus infection, IRF-3 is posttranslationally modified by protein phosphorylation at multiple serine and threonine residues, which are located in the carboxy terminus of IRF-3. A combination of IRF-3 deletion and point mutations localized the inducible phosphorylation sites to the region -ISNSHPLSLTSDQ- between amino acids 395 and 407; point mutation of residues Ser-396 and Ser-398 eliminated virus-induced phosphorylation of IRF-3 protein, although residues Ser-402, Thr-404, and Ser-405 were also targets. Phosphorylation results in the cytoplasm-to-nucleus translocation of IRF-3, DNA binding, and increased transcriptional activation. Substitution of the Ser-Thr sites with the phosphomimetic Asp generated a constitutively active form of IRF-3 that functioned as a very strong activator of promoters containing PRDI-PRDIII or ISRE regulatory elements. Phosphorylation also appears to represent a signal for virus-mediated degradation, since the virus-induced turnover of IRF-3 was prevented by mutation of the IRF-3 Ser-Thr cluster or by proteasome inhibitors. Interestingly, virus infection resulted in the association of IRF-3 with the CREB binding protein (CBP) coactivator, as detected by coimmunoprecipitation with anti-CBP antibody, an interaction mediated by the C-terminal domains of both proteins. Mutation of residues Ser-396 and Ser-398 in IRF-3 abrogated its binding to CBP. These results are discussed in terms of a model in which virus-inducible, C-terminal phosphorylation of IRF-3 alters protein conformation to permit nuclear translocation, association with transcriptional partners, and primary activation of IFN- and IFN-responsive genes.

Phosphorylation of IkappaBalpha in the C-terminal PEST domain by casein kinase II affects intrinsic protein stability.

The NF-kappaB/Rel transcription factors participate in the activation of immune system regulatory genes and viral early genes including the human immunodeficiency virus type 1 long terminal repeat. NF-kappaB/Rel proteins are coupled to inhibitory molecules, collectively termed IkappaB, which are responsible for cytoplasmic retention of NF-kappaB. Cell activation leads to the phosphorylation and degradation of IkappaBalpha, permitting NG-kappaB/Rel translocation to the nucleus and target gene activation. To further characterize the signaling events that contribute to IkappaBalpha phosphorylation, a kinase activity was isolated from Jurkat T cells that specifically interacted with IkappaBalpha in an affinity chromatography step and phosphorylated IkappaBalpha with high specificity in vitro. By using an in-gel kinase assay with recombinant IkappaBalpha as substrate, two forms of the kinase (43 and 38 kDa) were identified. Biochemical criteria and immunological cross-reactivity identified the kinase activity as the alpha catalytic subunit of casein kinase II (CKII). Deletion mutants of IkappaBalpha delta1 to delta4) localized phosphorylation to the C-terminal PEST domain of IkappaBalpha. Point mutation of residues T-291, S-283, and T-299 dramatically reduced phosphorylation of IkappaBalpha by the kinase in vitro. NIH-3T3 cells that stably expressed wild-type IkappaBalpha (wtIkappaB), double-point-mutated IkappaBalpha (T291A, S283A), or triple-point-mutated IkappaBalpha (T291A, S283A, T299A) under the control of the tetracycline-responsive promoter were generated. Constitutive phosphorylation of the triple point mutant was eliminated in vivo, although tumor necrosis factor-inducible IkappaBalpha degradation was unaffected. In cell lines and in transiently transfected cells, mutation of the CKII sites in IkappaBalpha resulted in a protein with increased intrinsic stability. Together with results demonstrating a role for N-terminal sites in inducer-mediated phosphorylation and degradation of IkappaBalpha, these studies indicate that CKII sites in the C-terminal PEST domain are important for constitutive phosphorylation and intrinsic stability of IkappaBalpha.

Essential role of interferon regulatory factor 3 in direct activation of RANTES chemokine transcription.

Localized and systemic cytokine production in virus-infected cells play an important role in the outcome of viral infection and pathogenicity. Activation of the interferon regulatory factors (IRF) in turn is a critical mediator of cytokine gene transcription. Recent studies have focused on the 55-kDa IRF-3 gene product as a direct transcriptional regulator of type 1 interferon (IFN-alpha and IFN-beta) activation in response to virus infection. Virus infection induces phosphorylation of IRF-3 on specific C-terminal serine residues and permits cytoplasmic-to-nuclear translocation of IRF-3, activation of DNA binding and transactivation potential, and association with the CBP/p300 coactivator. We previously generated constitutively active [IRF-3(5D)] and dominant-negative forms of IRF-3 that control IFN-beta and IFN-alpha gene expression. In an effort to characterize the range of immunoregulatory genes controlled by IRF-3, we now demonstrate that endogenous human RANTES gene transcription is directly induced in tetracycline-inducible IRF-3(5D)-expressing cells or paramyxovirus-infected cells. We also show that a dominant-negative IRF-3 mutant inhibits virus-induced expression of the RANTES promoter. Specific mutagenesis of overlapping ISRE-like sites located between nucleotides -123 and -96 in the RANTES promoter reduces virus-induced and IRF-3-dependent activation. These studies broaden the range of IRF-3 immunoregulatory target genes to include at least one member of the chemokine superfamily.

I kappaB alpha physically interacts with a cytoskeleton-associated protein through its signal response domain.

The I kappaB alpha protein is a key molecular target involved in the control of NF-kappaB/Rel transcription factors during viral infection or inflammatory reactions. This NF-kappaB-inhibitory factor is regulated by posttranslational phosphorylation and ubiquitination of its amino-terminal signal response domain that targets I kappaB alpha for rapid proteolysis by the 26S proteasome. In an attempt to identify regulators of the I kappaB alpha inhibitory activity, we undertook a yeast two-hybrid genetic screen, using the amino-terminal end of I kappaB alpha as bait, and identified 12 independent interacting clones. Sequence analysis identified some of these cDNA clones as Dlc-1, a sequence encoding a small, 9-kDa human homolog of the outer-arm dynein light-chain protein. In the two-hybrid assay, Dlc-1 also interacted with full-length I kappaB alpha protein but not with N-terminal-deletion-containing versions of I kappaB alpha. I kappaB alpha interacted in vitro with a glutathione S-transferase-Dlc-1 fusion protein, and RelA(p65) did not displace this association, demonstrating that p65 and Dlc-1 contact different protein motifs of I kappaB alpha. Importantly, in HeLa and 293 cells, endogenous and transfected I kappaB alpha coimmunoprecipitated with Myc-tagged or endogenous Dlc-1. Indirect immunofluorescence analyzed by confocal microscopy indicated that Dlc-1 and I kappaB alpha colocalized with both nuclear and cytoplasmic distribution. Furthermore, Dlc-1 and I kappaB alpha were found to associate with the microtubule organizing center, a perinuclear region from which microtubules radiate. Likewise, I kappaB alpha colocalized with alpha-tubulin filaments. Taken together, these results highlight an intriguing interaction between the I kappaB alpha protein and the human homolog of a member of the dynein family of motor proteins and provide a potential link between cytoskeleton dynamics and gene regulation.

Characterization of a functional NF-kappa B site in the human interleukin 1 beta promoter: evidence for a positive autoregulatory loop.

The -300 region of the interleukin 1 beta (IL-1 beta) promoter contains a functional NF-kappa B binding site composed of the decamer sequence 5'-GGGAAAATCC-3'. Probes representing the -300 region or the NF-kappa B site alone interacted with NF-kappa B proteins present in phorbol myristate acetate-, lipopolysaccharide-, or Sendai virus-induced myeloid cell extracts as well as recombinant NFKB1 (p50) and RelA (p65); furthermore, NF-kappa B protein-DNA complex formation was dissociated in vitro by the addition of recombinant I kappa B alpha. Mutation of the NF-kappa B site in the context of the IL-1 beta promoter reduced the responsiveness of the IL-1 beta promoter to various inducers, including phorbol ester, Sendai virus, poly(rI-rC), and IL-1 beta. A 4.4-kb IL-1 beta promoter fragment linked to a chloramphenicol acetyltransferase reporter gene was also preferentially inducible by coexpression of individual NF-kappa B subunits compared with a mutated IL-1 beta promoter fragment. When multiple copies of the IL-1 beta NF-kappa B site were linked to an enhancerless simian virus 40 promoter, this element was able to mediate phorbol ester- or lipopolysaccharide-inducible gene expression. In cotransfection experiments, RelA (p65) and c-Rel (p85) were identified as the main subunits responsible for the activation of the IL-1 beta NF-kappa B site; also, combinations of NFKB1 (p50) and RelA (p65) or c-Rel and RelA were strong transcriptional activators of reporter gene activity. The presence of a functional NF-kappa B binding site in the IL-1 beta promoter suggests that IL-1 positively autoregulates its own synthesis, since IL-1 is a strong inducer of NF-kappa B binding activity. Thus, the IL-1 beta gene may be considered as an important additional member of the family of cytokine genes regulated in part by the NF-kappa B/rel family of transcription factors.

Biological and biochemical inhibitors of the NF-kappa B/Rel proteins and cytokine synthesis.

The NF-kappa B/Rel family of transcription factors participates in the activation of a diverse range of genes involved in inflammation, immune response, lymphoid differentiation, growth control and development. The present review provides a brief overview of NF-kappa B/Rel activation and a detailed analysis of important biological and biochemical inhibitors of the NF-kappa B/Rel pathway. Given the pleiotropic role of NF-kappa B in controlling cytokines and other immunoregulatory genes, the inhibition of NF-kappa B activation by steroid hormones, antioxidants, protease inhibitors and other compounds may provide a pharmacological basis for interfering with pathological inflammatory conditions, cancer and AIDS.

The growing family of interferon regulatory factors.

Interferons (IFN) exert their multiple biological effects through the induction of expression of over 30 genes encoding proteins with antiviral, antiproliferative and immunomodulatory functions. Among the many IFN-inducible proteins are the Interferon Regulatory Factors (IRFs), a family of transcription regulators, originally consisting of the well-characterized IRF-1 and IRF-2 proteins; the family has now expanded to over 10 members and is still growing. The present review provides a detailed description of recently characterized IRF family members. Studies analyzing IRF-expressing cell lines and IRF knockout mice reveal that each member of the IRF family exerts distinct roles in biological processes such as pathogen response, cytokine signalling, cell growth regulation and hematopoietic development. Understanding the molecular mechanisms by which the IRFs affect these important cellular events and IFN expression will contribute to a greater understanding of events leading to various viral, immune and malignant disease states and will suggest novel strategies for antiviral and immune modulatory therapy.

NF-kappaB activation and HIV-1 induced apoptosis.

HIV infection leads to the progressive loss of CD4+ T cells and the near complete destruction of the immune system in the majority of infected individuals. High levels of viral gene expression and replication result in part from the activation of NF-kappaB transcription factors, which in addition to orchestrating the host inflammatory response also activate the HIV-1 long terminal repeat. NF-kappaB induces the expression of numerous cytokine, chemokine, growth factor and immunoregulatory genes, many of which promote HIV-1 replication. Thus, NF-kappaB activation represents a double edged sword in HIV-1 infected cells, since stimuli that induce an NF-kappaB mediated immune response will also lead to enhanced HIV-1 transcription. NF-kappaB has also been implicated in apoptotic signaling, protecting cells from programmed cell death under most circumstances and accelerating apoptosis in others. Therefore, activation of NF-kappaB can impact upon HIV-1 replication and pathogenesis at many levels, making the relationship between HIV-1 expression and NF-kappaB activation multi-faceted. This review will attempt to analyse the many faces and functions of NF-kappaB in the HIV-1 lifecycle.

Innovative Therapy, Monoclonal Antibodies and Beyond.

The seventh Edition of "Innovative Therapy, Monoclonal Antibodies and Beyond" Meeting took place in Milan, Italy, on January 27, 2017. The two sessions of the meeting were focused on: 1) Preclinical assays and novel biotargets; and 2) monoclonal antibodies, cell therapies and targeted molecules. Between these two sessions, a lecture entitled "HLA-antigens modulation and response to immune checkpoint inhibitor immunotherapy" was also presented. Despite the impressive successes in cancer immunotherapy in recent years, the response to immune based interventions occurs only in a minority of patients (∼20%). Several basic and translational mechanisms of resistance to immune checkpoint blockers (ICBs) were discussed during the meeting: 1. the impact of tumor microenvironment on the activity of immune system; 2. strategies to inhibit the cross-talk between extracellular matrix and myeloid-derived suppressor cells (MDSC) in the preclinical setting; 3. microRNA expression as a biomarker and as a target of therapy in non-small cell lung cancer (NSCLC); 4. the significance of complement activation pathways in response to immune checkpoint inhibitors; 5. the immunosuppressive activity of the microbiota by inducing IL-17 producing cells; and 6. modulation of HLA antigens as possible markers of response to ICB therapy. In order to overcome the deficiency in active anti-tumor T cells, several clinically applicable combination strategies were also discussed: 1. strategies to enhance the anticancer effects of immunogenic cell death inducing-chemotherapy; 2. the use of CAR T-cells in solid tumors; 3. the use of combination strategies involving oncolytic viruses and ICBs; 4. combinations of new ICBs with anti-PD-1/CTLA-4 therapy; and 4. combinations of targeted therapies and ICBs in melanoma. Overall, this conference emphasized the many novel strategies that are being investigated to improve the overall patient response to cancer immunotherapy. Optimization of biomarkers to accurately select patients who will respond to immunotherapy, coupled with combination strategies to improve long term patient survival remain critical challenges in the immuno-oncology field.