BackgroundMacrophages 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. In this study, we dissected the molecular mechanisms by which CCL2 neutralization inhibits HIV-1 replication in monocyte-derived macrophages (MDM), and the potential involvement of the innate restriction factors protein sterile alpha motif (SAM) histidine/aspartic acid (HD) domain containing 1 (SAMHD1) and apolipoprotein B mRNA-editing, enzyme-catalytic, polypeptide-like 3 (APOBEC3) family members.ResultsCCL2 neutralization potently reduced the number of p24 Gag+ cells during the course of either productive or single cycle infection with HIV-1. In contrast, CCL2 blocking did not modify entry of HIV-1 based Virus Like Particles, thus demonstrating that the restriction involves post-entry steps of the viral life cycle. Notably, the accumulation of viral DNA, both total, integrated and 2-LTR circles, was strongly impaired by neutralization of CCL2. Looking for correlates of HIV-1 DNA accumulation inhibition, we found that the antiviral effect of CCL2 neutralization was independent of the modulation of SAMHD1 expression or function. Conversely, a strong and selective induction of APOBEC3A expression, to levels comparable to those of freshly isolated monocytes, was associated with the inhibition of HIV-1 replication mediated by CCL2 blocking. Interestingly, the CCL2 neutralization mediated increase of APOBEC3A expression was type I IFN independent. Moreover, the transcriptome analysis of the effect of CCL2 blocking on global gene expression revealed that the neutralization of this chemokine resulted in the upmodulation of additional genes involved in the defence response to viruses.ConclusionsNeutralization of endogenous CCL2 determines a profound restriction of HIV-1 replication in primary MDM affecting post-entry steps of the viral life cycle with a mechanism independent of SAMHD1. In addition, CCL2 blocking is associated with induction of APOBEC3A expression, thus unravelling a novel mechanism which might contribute to regulate the expression of innate intracellular viral antagonists in vivo. Thus, our study may potentially lead to the development of new therapeutic strategies for enhancing innate cellular defences against HIV-1 and protecting macrophages from infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12977-014-0132-6) contains supplementary material, which is available to authorized users.

The data herein reported show that NBDHEX mediates efficient killing of both MDR1-Pgp and MRP1 over-expressing AML cells. Therefore, this drug can potentially be used as an effective agent for treating MDR in AML patients.

IntroductionDuring HIV infection the severe depletion of intestinal CD4+ T-cells is associated with microbial translocation, systemic immune activation, and disease progression. This study examined intestinal and peripheral CD4+ T-cell subsets reconstitution under combined antiretroviral therapy (cART), and systemic immune activation markers.MethodsThis longitudinal single-arm pilot study evaluates CD4+ T cells, including Th1 and Th17, in gut and blood and soluble markers for inflammation in HIV-infected individuals before (M0) and after eight (M8) months of cART. From January 2010 to December 2011, 10 HIV-1 naïve patients were screened and 9 enrolled. Blood and gut CD4+ T-cells subsets and cellular immune activation were determined by flow-cytometry and plasma soluble CD14 by ELISA. CD4+ Th17 cells were detected in gut biopsies by immunohistochemistry. Microbial translocation was measured by limulus-amebocyte-lysate assay to detect bacterial lipopolysaccharide (LPS) and PCR Real Time to detect plasma bacterial 16S rDNA.ResultsEight months of cART increased intestinal CD4+ and Th17 cells and reduced levels of T-cell activation and proliferation. The magnitude of intestinal CD4+ T-cell reconstitution correlated with the reduction of plasma LPS. Importantly, the magnitude of Th17 cells reconstitution correlated directly with blood CD4+ T-cell recovery.ConclusionShort-term antiretroviral therapy resulted in a significant increase in the levels of total and Th17 CD4+ T-cells in the gut mucosa and in decline of T-cell activation. The observation that pre-treatment levels of CD4+ and of CD8+ T-cell activation are predictors of the magnitude of Th17 cell reconstitution following cART provides further rationale for an early initiation of cART in HIV-infected individuals.Trial RegistrationClinicalTrials.gov NCT02097381

Most new cases of HCV infection are among people who inject drugs, many of whom are young women in their childbearing years. Women of reproductive age who are HCV+ display markers of ovarian senescence. This is associated with an increased burden in terms of infertility and adverse pregnancy outcomes, including stillbirth, miscarriage, fewer live births, and gestational diabetes. Early viral suppression with therapy is likely to mitigate these risks.

Abstract. In this study we elucidated the role of ATPbinding cassette (ABC) multi-drug transporter proteins and cellular factors such as Bcl-2 expression and CD33 downmodulation contributing to free and hP67.6 mAb linked calicheamicin-Á1 (CalC-Á1) resistance. We analyzed in a well designed HL60 cell system the relationship between the expression of ABC proteins, Bcl-2 and CD33 modulation with the activity of free and mAb-linked CalC-Á1. The results herein reported and discussed, strongly suggest that both MDR1-Pgp and MRP1 efflux systems are engaged by CalC-Á1, but only MDR1-Pgp over-expression efficiently abrogates drug cytotoxicity in MDR cells. Paradoxically, Bcl-2 expression, as observed for other anticancer compounds belonging to the enediyne family of drugs, confers CalC-Á1 susceptibility rather than resistance in HL60 cells. Further, the isolation of a resistant HL60 subline (HL60AL) that was developed by exposing the parental sensitive cells to subeffective doses of gemtuzumab ozogamicin (GO) over an extended period of time shows a reduced level of CD33 expression that represents an important escape mechanism of HL60 MDR cells to the cytotoxic effect of GO. IntroductionGemtuzumab ozogamicin (GO) is the first clinically validated cytotoxic immunoconjugate in which a humanised anti-CD33 antibody (hP67.6) is covalently linked to a derivative of Calicheamicin-Á1 (CalC-Á1) (1). More recently, the therapeutic potential of CD22-specific antibody-targeted chemotherapy using inotuzumab ozogamicin (CMC-544) is being evaluated at present in Phase I clinical trials in patients with non-Hodgkin's lymphoma (2). Further, a number of tumor-targeted immunoconjugates of CalC-Á1 is being explored preclinically for their therapeutic potential (3,4). However, several factors may affect the efficacy of CalC-Á1 immunoconjugates. These include the common issues of mAb therapy such as antibody specificity, heterogeneous target antigen expression and large inter-individual differences in cellular sensitivity to CalC-Á1 (5). Further, among individuals with de novo AML, the overexpression of the MDR1-P-glycoprotein (MDR1-Pgp), a 170-kDa protein that belongs to the ABC superfamily of proteins, is identified in the 20-75% of malignant cells (6). MDR1-Pgp acts as an efflux pump to remove anticancer drugs from cells, resulting in a simultaneous cross-resistance or multi-drug resistance (MDR) to various chemotherapeutics (7). Although MDR1-Pgp appears to be of biologic and clinical relevance (8), other ABC proteins may be involved in the outcome of GO-treated AML patients (9,10). One such protein, the multi-drug resistance-associated protein (MRP1), is distantly related to MDR1-Pgp, and like MDR1-Pgp, lowers intracellular drug accumulation by promoting drug efflux and MDR (11).Previous studies hypothesized an association between MDR1-Pgp and MRP1 expression and clinical responses to GO (8,12,13), others reported discrepant results attributed to the multi-factorial nature of drug resistance (14,15). Engagement of CD33 by GO results in im...

The survival of pediatric patients with cancer entities including osteosarcoma and Ewing's sarcoma (ES), remains extremely low hence novel treatment approaches are urgently needed. Therefore, based on the concept of targeted therapy, numerous potential targets for the treatment of these cancers have been evaluated pre-clinically or in some cases even clinically during the last decade. In ES the CD99 protein is an attractive target antigen. In this respect, a new entry site for therapeutic intervention may derive from specific human antibodies against CD99. Human scFvC7 was isolated from a semi-synthetic ETH-2 antibody phage library panned on the extracellular portion of recombinant human CD99 protein. The scFvC7 was genetically sequenced, tested for CD99 recognition on an array of recombinant CD99 fragments and measured for binding affinity by ELISA. Finally, it was tested for staining CD99 antigen on a large panel of tumor and normal cells and tissues by cytofluorimetric and immunohistochemical assays. The new antibody scFvC7 recognizes the CD99 extracellular domain included between residues 50 and 74 with a binding affinity of 2.4 x 10(-8) M. In contrast with all other antibodies to CD99 so far isolated, scFvC7 shows a unique specificity in cancer cell recognition: It stained prevalently ES cells while no or weak reactivity was observed on the majority of the other tumor and normal cells and tissues. Thanks to its properties the new anti-CD99 antibody here described represents the first step towards the construction of new selective ES therapeutics.

Background Lymphocyte-activation gene (LAG)3 is a 498 aa transmembrane type I protein acting as an immune inhibitory receptor. It is expressed on activated lymphocytes, natural killer cells and plasmacytoid dendritic cells. In activated lymphocytes, LAG3 expression is involved in negative control of cell activation/proliferation to ensure modulation and control of immune responses. In view of its deregulated expression in tumor-infiltrating lymphocytes, LAG3, together with the additional immune checkpoint inhibitors CTLA4 and PD1, is considered a major target in order to reverse the immunosuppression typically mounting in oncologic diseases. Since many patients still fail to respond to current immune checkpoints-based therapies, the identification of new effective immune inhibitors is a priority in the ongoing fight against cancer. Results We identified a novel human single-chain variable fragment (scFv) Ab against a conformational epitope of LAG3 by in vitro phage display technology using the recombinant antigen as a bait. This scFv (referred to as F7) was characterized in terms of binding specificity to both recombinant antigen and human LAG3-expressing cells. It was then rebuilt into an IgG format pre-optimized for clinical usage, and the resulting bivalent construct was shown to preserve its ability to bind LAG3 on human cells. Next, we analyzed the activity of the anti-LAG3 scFvF7 using two different antigen-specific CD8+ T lymphocyte clones as target cells. We proved that the reconstituted anti-LAG3 F7 Ab efficiently binds the cell membrane of both cell clones after peptide-activation. Still more significantly, we observed a striking increase in the peptide-dependent cell activation upon Ab treatment as measured in terms of IFN-γ release by both ELISA and ELISPOT assays. Conclusions Overall, the biotechnological strategy described herein represents a guiding development model for the search of novel useful immune checkpoint inhibitors. In addition, our functional data propose a novel candidate reagent for consideration as a cancer treatment.

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