The expression of CD45RA is generally associated with naive T cells. However, a subset of effector memory T cells re-expresses CD45RA (termed TEMRA) after antigenic stimulation with unknown molecular characteristics and functions. CD4 TEMRA cells have been implicated in protective immunity against pathogens such as dengue virus (DENV). Here we show that not only the frequency but also the phenotype of CD4 TEMRA cells are heterogeneous between individuals. These cells can be subdivided into two major subsets based on the expression of the adhesion G protein-coupled receptor GPR56, and GPR56 + TEMRA cells display a transcriptional and proteomic program with cytotoxic features that is distinct from effector memory T cells. Moreover, GPR56 + TEMRA cells have higher levels of clonal expansion and contain the majority of virus-specific TEMRA cells. Overall, this study reveals the heterogeneity of CD4 TEMRA cells and provides insights into T-cell responses against DENV and other viral pathogens.

Systems-based based approaches have begun to shed light on extrinsic factors that contribute to immune system variation. Among these, CMV (HHV-5, a β-herpesvirus) imposes a surprisingly profound impact. Most of the world's population is CMV, and the virus goes through three distinct infection phases en route to establishing lifelong détente with its host. Immune control of CMV in each phase recruits unique arms of host defense, and in turn the virus employs multiple immune-modulatory strategies that help facilitate the establishment of lifelong persistence. In this review, we explain how CMV shapes immunity and discuss the impact it may have on overall health.

APO2L/TRAIL (TNF-related apoptosis-inducing ligand) induces death of tumor cells through two agonist receptors, TRAIL-R1 and TRAIL-R2. We demonstrate here that N-linked glycosylation (N-glyc) plays also an important regulatory role for TRAIL-R1-mediated and mouse TRAIL receptor (mTRAIL-R)-mediated apoptosis, but not for TRAIL-R2, which is devoid of N-glycans. Cells expressing N-glyc-defective mutants of TRAIL-R1 and mouse TRAIL-R were less sensitive to TRAIL than their wild-type counterparts. Defective apoptotic signaling by N-glyc-deficient TRAIL receptors was associated with lower TRAIL receptor aggregation and reduced DISC formation, but not with reduced TRAIL-binding affinity. Our results also indicate that TRAIL receptor N-glyc impacts immune evasion strategies. The cytomegalovirus (CMV) UL141 protein, which restricts cell-surface expression of human TRAIL death receptors, binds with significant higher affinity TRAIL-R1 lacking N-glyc, suggesting that this sugar modification may have evolved as a counterstrategy to prevent receptor inhibition by UL141. Altogether our findings demonstrate that N-glyc of TRAIL-R1 promotes TRAIL signaling and restricts virus-mediated inhibition.

Ewing's sarcoma (ES) is the second most frequent pediatric bone tumor also arising in soft tissues (15% of cases). The prognosis of patients with clinically detectable metastases at diagnosis, not responding to therapy or with disease relapse, is still very poor. Among new therapeutic approaches, bisphosphonates represent promising adjuvant molecules to chemotherapy to limit the osteolytic component of bone tumors and to protect from bone metastases. The combined effects of zoledronic acid and mafosfamide were investigated on cell proliferation, viability, apoptosis, and cell cycle distribution of human ES cell lines differing in their p53 and p16/ink4 status. ES models were developed to reproduce both soft tissue and intraosseous tumor development. Mice were treated with 100 μg/kg zoledronic acid (two or four times per week) and/or ifosfamide (30 mg/kg, one to three cycles of three injections). ES cell lines showed different sensitivities to zoledronic acid and mafosfamide at the cell proliferation level, with no correlation with their molecular status. Both drugs induced cell cycle arrest, but in the S or G 2 M phase, respectively. In vivo, zoledronic acid had no effect on soft tissue tumor progression, although it dramatically inhibited ES development in bone. When combined with ifosfamide, zoledronic acid exerted synergistic effects in the soft tissue model: Its combination with one cycle of ifosfamide resulted in an inhibitory effect similar to three cycles of ifosfamide alone. This very promising result could allow clinicians to diminish the doses of chemotherapy.

Purpose: Osteosarcoma and Ewing's sarcoma are high-grade neoplasms typically arising in the bones of children and adolescents. Despite improvement in therapy, the five-year survival rate is only 20% for patients not responding to treatment or presenting with metastases. Among new therapeutic strategies, the efficacy of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF superfamily with strong antitumoral activity and minimal toxicity to most normal cells and tissues, was investigated by complementary approaches both in vitro and in preclinical models.Experimental design: The sensitivity of osteosarcoma and Ewing's sarcoma cell lines to TRAIL was investigated in vitro by determining TRAIL receptor expression together with TRAIL effects on cell viability and apoptosis. Complementary preclinical studies were carried out in respective tumor models by inoculation of osteosarcoma or Ewing's sarcoma tumor cells in paraosseous location. In addition, a model of lung nodule dissemination was developed by i.v. injection of osteosarcoma cells.Results: In vitro, both osteosarcoma and Ewing's sarcoma cells that express the TRAIL death receptors were highly sensitive to TRAIL-induced caspase-8-mediated apoptosis. TRAIL administered in vivo by nonviral gene therapy inhibited primary bone tumor incidence and growth by 87% and prevented tumorinduced osteolysis, leading to a significant 2-fold increase in animal survival 40 days after tumor induction. Furthermore, TRAIL inhibited tumor nodule dissemination in lungs and increased survival in an osteosarcoma model.Conclusion: These findings suggest that TRAIL is a promising candidate for the development of new therapeutic strategies in the most frequent malignant primary bone tumors.