Suppression of NF-κB and AP-1 activation in monocytic cells persistently infected with measles virus

Integrated Analysis of miRNA-mRNA Expression in Mink Lung Epithelial Cells Infected With Canine Distemper Virus

Canine distemper (CD) caused by canine distemper virus (CDV) is one of the major infectious diseases in minks, bringing serious economic losses to the mink breeding industry. By an integrated analysis of microRNA (miRNA)-messenger RNA (mRNA), the present study analyzed the changes in the mink transcriptome upon CDV infection in mink lung epithelial cells (Mv. l. Lu cells) for the first time. A total of 4,734 differentially expressed mRNAs (2,691 upregulated and 2,043 downregulated) with |log2(FoldChange) |>1 and P-adj<0.05 and 181 differentially expressed miRNAs (152 upregulated and 29 downregulated) with |log2(FoldChange) |>2 and P-adj<0.05 were identified. Gene Ontology (GO) enrichment indicated that differentially expressed genes (DEGs) were associated with various biological processes and molecular function, such as response to stimulus, cell communication, signaling, cytokine activity, transmembrane signaling receptor activity and signaling receptor activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the combination of miRNA and mRNA was done for immune and inflammatory responses, such as Janus kinase (JAK)-signal transducer and activator (STAT) signaling pathway and nuclear factor (NF)-kappa B signaling pathway. The enrichment analysis of target mRNA of differentially expressed miRNA revealed that mir-140-5p and mir-378-12 targeted corresponding genes to regulate NF-kappa B signaling pathway. JAK-STAT signaling pathway could be modulated by mir-425-2, mir-139-4, mir-140-6, mir-145-3, mir-140-5p and mir-204-2. This study compared the influence of miRNA-mRNA expression in Mv. l. Lu cells before and after CDV infection by integrated analysis of miRNA-mRNA and analyzed the complex network interaction between virus and host cells. The results can help understand the molecular mechanism of the natural immune response induced by CDV infection in host cells.

Precise tumor immune rewiring via synthetic CRISPRa circuits gated by concurrent gain/loss of transcription factors

Reinvigoration of antitumor immunity has recently become the central theme for the development of cancer therapies. Nevertheless, the precise delivery of immunotherapeutic activities to the tumors remains challenging. Here, we explore a synthetic gene circuit-based strategy for specific tumor identification, and for subsequently engaging immune activation. By design, these circuits are assembled from two interactive modules, i.e., an oncogenic TF-driven CRISPRa effector, and a corresponding p53-inducible off-switch (NOT gate), which jointly execute an AND-NOT logic for accurate tumor targeting. In particular, two forms of the NOT gate are developed, via the use of an inhibitory sgRNA or an anti-CRISPR protein, with the second form showing a superior performance in gating CRISPRa by p53 loss. Functionally, the optimized AND-NOT logic circuit can empower a highly specific and effective tumor recognition/immune rewiring axis, leading to therapeutic effects in vivo. Taken together, our work presents an adaptable strategy for the development of precisely delivered immunotherapy.

“Reinvigoration of antitumor immunity has recently become the central theme for the development of cancer therapies. Here the authors present an adaptable gene circuit to harness the CRISPRa for tumorlocalized immune activation.”

Persistent high plasma levels of sCD163 and sCD14 in adult patients with measles virus infection

BACKGROUND AND AIMS

Measles is an infectious disease that represents a serious public health problem worldwide, being associated with increased susceptibility to secondary infections, especially in the respiratory and gastrointestinal tracts. The aim of this study was to evaluate sCD163 and sCD14 levels in measles virus (MV) infected patients, as markers of immune activation, in order to better understand their role in the pathogenesis of the disease. TNF-α plasma levels were also evaluated.

METHODS

sCD163, sCD14 and TNF-α were measured by ELISA in plasma samples of 27 MV infected patients and 27 healthy donors (HD) included as controls.

RESULTS

At the time of hospital admission, sCD163 and sCD14 levels were significantly higher in MV infected patients than in HD, while a decrease in TNF-α levels were found even if without statistical significance. sCD163 and sCD14 levels were significantly decreased after two months from acute infection compared to hospital admission although they remained significantly higher compared to HD. TNF-α levels increased significantly during the follow-up period. Considering clinical parameters, sCD163 levels positively correlated with aspartate aminotransferase, white blood cell count and neutrophils rate, while negatively correlated with the lymphocyte percentage. sCD14 levels positively correlated with the neutrophil and lymphocyte percentages.

CONCLUSIONS

These results indicate that, despite the resolution of symptoms, an important macrophage/monocyte activation persists in measles patients, even after two months from infection.

Zika, dengue and yellow fever viruses induce differential anti-viral immune responses in human monocytic and first trimester trophoblast cells

Zika virus (ZIKV) is a mosquito-borne flavivirus associated with severe neonatal birth defects, but the causative mechanism is incompletely understood. ZIKV shares sequence homology and early clinical manifestations with yellow fever virus (YFV) and dengue virus (DENV) and are all transmitted in urban cycles by the same species of mosquitoes. However, YFV and DENV have been rarely reported to cause congenital diseases. Here, we compared infection with a contemporary ZIKV strain (FSS13025) to YFV17D and DENV-4 in human monocytic cells (THP-1) and first-trimester trophoblasts (HTR-8). Our results suggest that all three viruses have similar tropisms for both cells. Nevertheless, ZIKV induced strong type 1 IFN and inflammatory cytokine and chemokine production in monocytes and peripheral blood mononuclear cells. Furthermore, ZIKV infection in trophoblasts induced lower IFN and higher inflammatory immune responses. Placental inflammation is known to contribute to the risk of brain damage in preterm newborns. Inhibition of toll-like receptor (TLR)3 and TLR8 each abrogated the inflammatory cytokine responses in ZIKV-infected trophoblasts. Our findings identify a potential link between maternal immune activation and ZIKV-induced congenital diseases, and a potential therapeutic strategy that targets TLR-mediated inflammatory responses in the placenta.

Bifidobacterium adolescentis IM38 ameliorates high-fat diet-induced colitis in mice by inhibiting NF-κB activation and lipopolysaccharide production by gut microbiota

Gut microbiota play essential roles in the regulation of human metabolism via symbiotic interactions with the host. Prolonged consumption of high-fat diet (HFD) elevates the Firmicutes to Bacteroidetes ratio and lipopolysaccharide (LPS) production by gut microbiota, thereby increasing the probability of developing metabolic and immune disorders such as obesity and colitis. The use of probiotics with anti-inflammatory properties has been suggested to counteract this effect. Here, we tested whether Bifidobacterium adolescentis IM38, which inhibited nuclear factor-kappa B (NF-κB) activation in Caco-2 cells and peritoneal macrophages and inhibited Escherichia coli LPS production, exerted an anticolitic effect in mice with HFD-induced obesity. Oral administration of IM38 (2×10⁹CFU/mouse per day) for 6 weeks in mice with HFD-induced obesity inhibited whole-body and epididymal fat weight gain. IM38 also increased HFD-suppressed expression of interleukin (IL)-10 and tight junction proteins but significantly downregulated HFD-induced NF-κB activation and tumor necrosis factor expression in the colon. IM38 inhibited differentiation into helper T17 cells and reduced IL-17 levels in the colon of mice with HFD-induced obesity but increased HFD-suppressed differentiation into regulatory T cells and IL-10 levels. Furthermore, treatment with IM38 lowered the HFD-induced LPS levels in blood and colonic fluid, as well as the Proteobacteria to Bacteroidetes ratio in gut microbiota. Therefore, we suggest that IM38 can inhibit HFD-induced LPS production in gut microbiota through the regulation of Proteobacteria to Bacteroidetes ratio and NF-κB activation in the colon, which ultimately attenuates colitis. Thus, IM38 may be a suitable ingredient of functional foods designed for treating or preventing colitis.

Measles Virus Infection Inactivates Cellular Protein Phosphatase 5 with Consequent Suppression of Sp1 and c-Myc Activities

Measles virus (MeV) causes several unique syndromes, including transient immunosuppression. To clarify the cellular responses to MeV infection, we previously analyzed a MeV-infected epithelial cell line and a lymphoid cell line by microarray and showed that the expression of numerous genes was up- or downregulated in the epithelial cells. In particular, there was a characteristic comprehensive downregulation of housekeeping genes during late stage infection. To identify the mechanism underlying this phenomenon, we examined the phosphorylation status of transcription factors and kinase/phosphatase activities in epithelial cells after infection. MeV infection inactivated cellular protein phosphatase 5 (PP5) that consequently inactivated DNA-dependent protein kinase, which reduced Sp1 phosphorylation levels, and c-Myc degradation, both of which downregulated the expression of many housekeeping genes. In addition, intracellular accumulation of viral nucleocapsid inactivated PP5 and subsequent downstream responses. These findings demonstrate a novel strategy of MeV during infection, which causes the collapse of host cellular functions.

IMPORTANCE

Measles virus (MeV) is one of the most important pathogens in humans. We previously showed that MeV infection induces the comprehensive downregulation of housekeeping genes in epithelial cells. By examining this phenomenon, we clarified the molecular mechanism underlying the constitutive expression of housekeeping genes in cells, which is maintained by cellular protein phosphatase 5 (PP5) and DNA-dependent protein kinase. We also demonstrated that MeV targets PP5 for downregulation in epithelial cells. This is the first report to show how MeV infection triggers a reduction in overall cellular functions of infected host cells. Our findings will help uncover unique pathogenicities caused by MeV.

A West Nile virus NS4B-P38G mutant strain induces cell intrinsic innate cytokine responses in human monocytic and macrophage cells

Previous studies have shown that an attenuated West Nile virus (WNV) nonstructural (NS) 4B-P38G mutant induces stronger innate and adaptive immune responses than wild-type WNV in mice, which has important applications to vaccine development. To investigate the mechanism of immunogenicity, we characterized WNV NS4B-P38G mutant infection in two human cell lines-THP-1 cells and THP-1 macrophages. Although the NS4B-P38G mutant produced more viral RNA than the parental WNV NY99 in both cell types, there was no detectable infectious virus in the supernatant of either cell type. Nonetheless, the attenuated mutant boosted higher innate cytokine responses than virulent parental WNV NY99 in these cells. The NS4B-P38G mutant infection of THP-1 cells led to more diverse and robust innate cytokine responses than that seen in THP-1 macrophages, which were mediated by toll-like receptor (TLR)7 and retinoic acid-inducible gene 1(RIG-I) signaling pathways. Overall, these results suggest that a defective viral life cycle during NS4B-P38G mutant infection in human monocytic and macrophage cells leads to more potent cell intrinsic innate cytokine responses.

Proteome profiling of virus-host interactions of wild type and attenuated measles virus strains

Quantitative gel-based proteomics (2D DIGE coupled to MALDI-TOF/TOF MS) has been used to investigate the effects of different measles virus (MV) strains on the host cell proteome. A549/hSLAM cells were infected either with wild type MV strains, an attenuated vaccine or a multiple passaged Vero cell adapted strain. By including interferon beta treatment as a control it was possible to distinguish between the classical antiviral response and changes induced specifically by the different strains. Of 38 differentially expressed proteins in total (p-value ≤0.05, fold change ≥2), 18 proteins were uniquely modulated following MV infection with up to 9 proteins specific per individual strain. Interestingly, wt strains displayed distinct protein patterns particularly during the late phase of infection. Proteins were grouped into cytoskeleton, metabolism, transcription/translation, immune response and mitochondrial proteins. Bioinformatics analysis revealed mostly changes in proteins regulating cell death and apoptosis. Surprisingly, wt strains affected the cytokeratin system much stronger than the vaccine strain. To our knowledge, this is the first study on the MV-host proteome addressing interstrain differences.

BIOLOGICAL SIGNIFICANCE

In the present study we investigated the host cell proteome upon measles virus (MV) infection. The novelty about this study is the side-by side comparison of different strains from the same virus, which has not been done at the proteome level for any other virus including MV. We used different virus strains including a vaccine strain, wild type isolates derived from MV-infected patients as well as a Vero cell adapted strain, which serves as an intermediate between vaccine and wild type strain. We observed differences between vaccine and wild type strains as well as common features between different wild type strains. Perhaps one of the most surprising findings was that differences did not only occur between wild type and vaccine or Vero cell adapted strains but also between different wild type strains. In fact our study suggests that besides the cytokeratin and the IFN system wild type viruses seem to differ as much among each other than from vaccine strains. Thus our results are suggestive of complex and diverse virus-host interactions which differ considerably between different wild type strains. Our data indicate that interstrain differences are prominent and have so far been neglected by proteomics studies.

RIG-I-like receptors and intracellular Toll-like receptors in antiviral immunity

Viral recognition by pattern recognition receptors is a crucial step in antiviral immunity. Toll-like receptors (TLRs) and RIG-I-like receptors (RLRs) represent two classes of nucleic acid-sensing pattern recognition receptors that play a major role in inducing an antiviral response. Whereas nucleic acid-recognizing TLRs are transmembrane receptors localized in endosomes, RLRs are distributed within the cytoplasm. Recognition of viral nucleic acid by either class of receptors results in activation of downstream signaling pathways. This eventually induces expression of type I IFN and inflammatory cytokines via activation of the transcription factors IRF3, NF-κB and AP-1. Many viruses, such as the extensively studied family of Paramyxoviridae, have evolved sophisticated mechanisms to evade these responses. This review focuses on the differences between viral recognition, signaling pathways and induction of adaptive immunity evoked by RLRs and intracellular TLRs.

Classical swine fever virus failed to activate nuclear factor-kappa b signaling pathway both in vitro and in vivo

BACKGROUND

Classical swine fever virus (CSFV) is the cause of CSF which is a severe disease of pigs, leading to heavy economic losses in many regions of the world. Nuclear factor-kappa B (NF-κB) is a critical regulator of innate and adaptive immunity, and commonly activated upon viral infection. In our previous study, we found that CSFV could suppress the maturation and modulate the functions of monocyte-derived dendritic cells (Mo-DCs) without activating NF-κB pathway. To further prove the effects of CSFV on the NF-κB signaling pathway, we investigated the activity of NF-κB after CSFV infection in vivo and in vitro.

METHODS

Attenuated Thiverval strain and virulent wild-type GXW-07 strain were used as challenge viruses in this study. Porcine kidney 15 (PK-15) cells were cultured in vitro and peripheral blood mononuclear cells (PBMCs) were isolated from the blood of CSFV-infected pigs. DNA binding of NF-κB was measured by electrophoretic mobility shift assays (EMSA), NF-κB p65 translocation was detected using immunofluorescent staining, and p65/RelA and IκBα expression was measured by Western Blotting.

RESULTS

Infection of cells with CSFV in vitro and in vivo showed that compared with tumor necrosis factor alpha (TNF-α) stimulated cells, there was no distinct DNA binding band of NF-κB, and no significant translocation of p65/RelA from the cytoplasm to the nucleus was observed, which might have been due to the apparent lack of IkBa degradation.

CONCLUSIONS

CSFV infection had no effect on the NF-κB signaling pathway, indicating that CSFV could evade host activation of NF-κB during infection.

Measles virus, immune control, and persistence

Measles remains one of the most important causes of child morbidity and mortality worldwide with the greatest burden in the youngest children. Most acute measles deaths are owing to secondary infections that result from a poorly understood measles-induced suppression of immune responses. Young children are also vulnerable to late development of subacute sclerosing panencephalitis, a progressive, uniformly fatal neurologic disease caused by persistent measles virus (MeV) infection. During acute infection, the rash marks the appearance of the adaptive immune response and CD8(+) T cell-mediated clearance of infectious virus. However, after clearance of infectious virus, MeV RNA persists and can be detected in blood, respiratory secretions, urine, and lymphoid tissue for many weeks to months. This prolonged period of virus clearance may help to explain measles immunosuppression and the development of lifelong immunity to re-infection, as well as occasional infection of the nervous system. Once MeV infects neurons, the virus can spread trans-synaptically and the envelope proteins needed to form infectious virus are unnecessary, accumulate mutations, and can establish persistent infection. Identification of the immune mechanisms required for the clearance of MeV RNA from multiple sites will enlighten our understanding of the development of disease owing to persistent infection.

Viral takeover of the host ubiquitin system

Like the other more well-characterized post-translational modifications (phosphorylation, methylation, acetylation, acylation, etc.), the attachment of the 76 amino acid ubiquitin (Ub) protein to substrates has been shown to govern countless cellular processes. As obligate intracellular parasites, viruses have evolved the capability to commandeer many host processes in order to maximize their own survival, whether it be to increase viral production or to ensure the long-term survival of latently infected host cells. The first evidence that viruses could usurp the Ub system came from the DNA tumor viruses and Adenoviruses, each of which use Ub to dysregulate the host cell cycle (Scheffner et al., 1990; Querido et al., 2001). Today, the list of viruses that utilize Ub includes members from almost every viral class, encompassing both RNA and DNA viruses. Among these, there are examples of Ub usage at every stage of the viral life cycle, involving both ubiquitination and de-ubiquitination. In addition to viruses that merely modify the host Ub system, many of the large DNA viruses encode their own Ub modifying machinery. In this review, we highlight the latest discoveries regarding the myriad ways that viruses utilize Ub to their advantage.

Decreased expression in nuclear factor-κB essential modulator due to a novel splice-site mutation causes X-linked ectodermal dysplasia with immunodeficiency

X-linked ectodermal dysplasia with immunodeficiency (XL-ED-ID) is caused by hypomorphic mutations in NEMO, which encodes nuclear factor-kappaB (NF-κB) essential modulator. We identified a novel mutation, 769-1 G>C, at the splicing acceptor site of exon 7 in NEMO in a Japanese patient with XL-ED-ID. Although various abnormally spliced NEMO messenger RNAs (mRNAs) were observed, a small amount of wild-type (WT) mRNA was also identified. Decreased NEMO protein expression was detected in various lineages of leukocytes. Although one abnormally spliced NEMO protein showed residual NF-κB transcription activity, it did not seem to exert a dominant-negative effect against WT-NEMO activity. CD4(+) T cell proliferation was impaired in response to measles and mumps, but not rubella. These results were consistent with the clinical and laboratory findings of the patient, suggesting the functional importance of NEMO against specific viral infections. The 769-1 G>C mutation is responsible for decreased WT-NEMO protein expression, resulting in the development of XL-ED-ID.

A nonredundant role for canonical NF-κB in human myeloid dendritic cell development and function

The plastic role of dendritic cells (DCs) in the regulation of immune responses has made them interesting targets for immunotherapy, but also for pathogens or tumors to evade immunity. Functional alterations of DCs are often ascribed to manipulation of canonical NF-κB activity. However, though this pathway has been linked to murine myeloid DC biology, a detailed analysis of its importance in human myeloid DC differentiation, survival, maturation, and function is lacking. The myeloid DC subsets include interstitial DCs and Langerhans cells. In this study, we investigated the role of canonical NF-κB in human myeloid DCs generated from monocytes (monocyte-derived DCs [mo-DCs]) or CD34(+) progenitors (CD34-derived myeloid DCs [CD34-mDCs]). Inhibition of NF-κB activation during and after mo-DC, CD34-interstitial DC, or CD34-Langerhans cell differentiation resulted in apoptosis induction associated with caspase 3 activation and loss of mitochondrial transmembrane potential. Besides regulating survival, canonical NF-κB activity was required for the acquisition of a DC phenotype. Despite phenotypic differences, however, Ag uptake, costimulatory molecule and CCR7 expression, as well as T cell stimulatory capacity of cells generated under NF-κB inhibition were comparable to control DCs, indicating that canonical NF-κB activity during differentiation is redundant for the development of functional APCs. However, both mo-DC and CD34-mDC functionality were reduced by NF-κB inhibition during activation. In conclusion, canonical NF-κB activity is essential for the development and function of mo-DCs as well as CD34-mDCs. Insight into the role of this pathway may help in understanding how pathogens and tumors escape immunity and aid in developing novel treatment strategies aiming to interfere with human immune responses.

The battle between virus and host: modulation of Toll-like receptor signaling pathways by virus infection

In order to establish an infection, viruses need to either suppress or escape from host immune defense systems. Recent immunological research has focused on innate immunity as the first line of host defense, especially pattern recognition molecules such as Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), and NOD-like receptors (NLRs). Various microbial components are recognized by their vague and common molecular shapes so-called, pathogen-associated molecular patterns (PAMPs). PAMPs induce inflammatory reactions mediated by the activation of the transcription factor, NF-κB, and by interferons, which lead to an antiviral immune response. Viruses have the capacity to suppress or escape from this pattern recognition molecule-mediated antimicrobial response in various ways. In this paper, we review the various strategies used by viruses to modulate the pattern recognition molecule-mediated innate immune response.

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

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

Nuclear factor kappa B and hepatitis viruses

BACKGROUND

Hepatitis can be caused by a number of viruses, which have similar clinical manifestations and render infected individuals at high risk of death from cirrhosis and liver cancer. Current therapies for hepatitis have limited effects and unsatisfactory patient outcomes. Nuclear factor kappa B (NF-kappaB) is critical for immune and inflammatory responses. During its lifetime the cell demands specific and highly regulated control of NF-kappaB activity.

OBJECTIVE

To develop novel strategies to overcome various hepatitides and related liver cancer with NF-kappaB as the key point.

METHODS

All aspects of NF-kappaB control with regard to hepatitis are covered.

RESULTS/CONCLUSION

NF-kappaB plays an important role in the process of hepatitis and is hypothesized to be an anti-cancer factor in the subsequent inflammation-associated hepatocarcinogenesis.

Measles virus P protein suppresses Toll-like receptor signal through up-regulation of ubiquitin-modifying enzyme A20

We recently reported that the activation of NF-kappaB and AP-1 was suppressed in monocytes infected with measles virus, but not in infected epithelial cells. This cell-type-specific suppression of the inflammatory response represents a potential for measles virus to evade host immune system. In the current study, we examined the suppression mechanism of lipopolysaccharide (LPS)-induced, namely Toll-like receptor 4 (TLR4)-mediated, activation of NF-kappaB and AP-1 in measles virus-infected monocytic cells. In the infected cells, LPS treatment failed to induce the formation of active protein kinase complex containing TAK1, TAB2 and tumor necrosis factor receptor-associated factor 6 (TRAF6), dissociate from TLR complexes containing Interleukin-1 receptor-associated kinase 1 (IRAK1). Ubiquitin-modifying enzyme A20, which is a host negative feedback regulator of NF-kappaB, was dramatically up-regulated in infected monocytic cells, but not in infected epithelial cells. Suppression of A20 expression by siRNA restored LPS-induced signaling in infected cells. Measles virus phosphoprotein (P protein) expression was necessary and sufficient for the induction of A20. P protein interacted indirectly with a negative regulatory motif in the A20 gene promoter, and released the suppression of A20 transcription, independent of the activation of NF-kappaB.