Entry into the lytic cycle exposes EBV-infected cells to NK cell killing via upregulation of the MICB ligand for NKG2D and activation of the CD56 and NKG2AKIRCD56 subsets.

The Epstein-Barr virus (EBV) is usually acquired during infancy as an asymptomatic infection and persists throughout life in a latent state under the control of the host immune system. However, EBV is associated with various malignant diseases that preferentially develop in immunodeficient individuals. Accumulating evidence suggests an important role for NK cells, though the mechanisms by which EBV evades or triggers NK cell responses are poorly understood.

Induction of the antiviral factors APOBEC3A and RSAD2 upon CCL2 neutralization in primary human macrophages involves NF-κB, JAK/STAT, and gp130 signaling.

The CCL2/CC chemokine receptor 2 axis plays key roles in the pathogenesis of HIV-1 infection. We previously reported that exposure of monocyte-derived macrophages to CCL2 neutralizing antibody (αCCL2 Ab) restricted HIV-1 replication at postentry steps of the viral life cycle. This effect was associated with induction of transcripts coding for innate antiviral proteins, including APOBEC3A and RSAD2.

Absence of ATM leads to altered NK cell function in mice.

Ataxia-telangiectasia (A-T) is a rare disorder caused by genetic defects of A-T mutated (ATM) kinase, a key regulator of stress response, and characterized by neurodegeneration, immunodeficiency, and high incidence of cancer. Here we investigated NK cells in a mouse model of A-T (Atm) showing that they are strongly impaired at killing tumor cells due to a block of early signaling events. On the other hand, in Atm littermates with thymic lymphoma NK cell cytotoxicity is enhanced as compared with ATM-proficient mice, possibly via tumor-produced TNF-α.

Impact of IL-15 and latency reversing agent combinations in the reactivation and NK cell-mediated suppression of the HIV reservoir.

Inhibitors of histone deacetylases (HDACis) are major latency reversing agent (LRA) candidates in 'shock and kill' strategies to eradicate the HIV reservoir in infected patients. The poor achievements of initial HDACi-based trials and subsequent studies have highlighted the need for more efficient approaches such as combinatory and immunostimulating therapies. Here we studied combinations of IL-15 with pan-HDACi (Vorinostat, Romidepsin, Panobinostat) or class I selective-HDACi (Entinostat) with or without a PKC agonist (Prostratin) for their impact on in vitro reactivation and NK cell-mediated suppression of latent HIV.

Transcriptome Profiling of Human Monocyte-Derived Macrophages Upon CCL2 Neutralization Reveals an Association Between Activation of Innate Immune Pathways and Restriction of HIV-1 Gene Expression.

Macrophages are key targets of human immunodeficiency virus type 1 (HIV-1) infection and main producers of the proinflammatory chemokine CC chemokine ligand 2 (CCL2), whose expression is induced by HIV-1 both and . We previously found that CCL2 neutralization in monocyte-derived macrophages (MDMs) strongly inhibited HIV-1 replication affecting post-entry steps of the viral life cycle. Here, we used RNA-sequencing to deeply characterize the cellular factors and pathways modulated by CCL2 blocking in MDMs and involved in HIV-1 replication restriction.

SAMHD1 phosphorylation and cytoplasmic relocalization after human cytomegalovirus infection limits its antiviral activity.

SAMHD1 is a host restriction factor that functions to restrict both retroviruses and DNA viruses, based on its nuclear deoxynucleotide triphosphate (dNTP) hydrolase activity that limits availability of intracellular dNTP pools. In the present study, we demonstrate that SAMHD1 expression was increased following human cytomegalovirus (HCMV) infection, with only a modest effect on infectious virus production. SAMHD1 was rapidly phosphorylated at residue T592 after infection by cellular cyclin-dependent kinases, especially Cdk2, and by the viral kinase pUL97, resulting in a significant fraction of phosho-SAMHD1 being relocalized to the cytoplasm of infected fibroblasts, in association with viral particles and dense bodies.

Wnt3a/β-Catenin Signaling Conditions Differentiation of Partially Exhausted T-effector Cells in Human Cancers.

In this study, we investigated the role of the Wnt/β-catenin signaling pathway in antitumor immune responses. We report that the concentration of secreted Wnt3a was significantly higher in conditioned medium from tumor or nontumor tissues obtained from all hepatocellular carcinoma or colorectal cancer patients tested, than in serum of healthy donors or patients. In addition, both Wnt3a and β-catenin were overexpressed by tumor-infiltrating and nontumor-infiltrating CD4 or CD8 T cells.

Understanding the regulation of APOBEC3 expression: Current evidence and much to learn.

The apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3 (APOBEC3) family of cytosine deaminases plays crucial roles in innate immunity through the ability of restricting viral replication by deamination and mutation of viral genomes. The antiviral function of these proteins was first discovered when research in the field of HIV infection revealed that one member of the family, namely APOBEC3G, restricts HIV infection in T lymphocytes and that the viral infectivity factor protein drives the proteosomal degradation of this enzyme, thus overriding its antiviral function. Recent advances in cancer genomics, together with biochemical characterization of the APOBEC3 enzymes, have now implicated some family members in somatic mutagenesis during carcinogenesis.

Bovine Lactoferrin-Induced CCL1 Expression Involves Distinct Receptors in Monocyte-Derived Dendritic Cells and Their Monocyte Precursors.

Lactoferrin (LF) exhibits a wide range of immunomodulatory activities including modulation of cytokine and chemokine secretion. In this study, we demonstrate that bovine LF (bLF) up-modulates, in a concentration- and time-dependent manner, CCL1 secretion in monocytes (Mo) at the early stage of differentiation toward dendritic cells (DCs), and in fully differentiated immature Mo-derived DCs (MoDCs). In both cell types, up-modulation of CCL1 secretion is an early event following bLF-mediated enhanced accumulation of CCL1 transcripts.

The CCL2/CCR2 Axis in the Pathogenesis of HIV-1 Infection: A New Cellular Target for Therapy?

The identification of chemokine receptors as necessary co-receptors for HIV entry into target cells represented a breakthrough in the understanding of the pathogenesis of this viral infection. Since this initial discovery, it was unraveled that chemokines, in addition to their role in blocking viral entry by binding to co-receptors, have other functions in HIV pathogenesis. Indeed, chemokines can either inhibit or enhance HIV replication, and these effects may involve both entry and post-entry events of the viral life cycle.

Endogenous CCL2 neutralization restricts HIV-1 replication in primary human macrophages by inhibiting viral DNA accumulation.

Background: Macrophages are key targets of HIV-1 infection. We have previously described that the expression of CC chemokine ligand 2 (CCL2) increases during monocyte differentiation to macrophages and it is further up-modulated by HIV-1 exposure. Moreover, CCL2 acts as an autocrine factor that promotes viral replication in infected macrophages.