Are human V\u3b42pos T cells really resistant to aging and Human Cytomegalovirus infection?

In their recent paper, Weili Xu et al. [1] described the different behaviors of V\u3b41pos and V\u3b42pos T cell subsets in response to lifelong stress and claimed that V\u3b42pos T cells are not affected by aging and Human Cytomegalovirus (HCMV) infection. While we agree that these two \u3b3\u3b4 T cell subsets diverge both in phenotype/function and in tissue distribution, we are somewhat surprised that authors did not take into account the several previously published and contradictory experimental evidence in regards to senescence of V\u3b42pos T cells [2,3]. These latter studies reported that HCMV infection not only induces a clonal expansion of a distinct V\u3b39neg/V\u3b42pos T cell subset, but also determines a concomitant adaptive differentiation from CD27high na\uefve cells to CD27low/neg terminal-effectors. However, Weili Xu et al. argued that the expression and kinetics of both CD27 and CD45RA surface markers do not change and follow the homeostatic changes of V\u3b42pos T cells. This statement goes in the opposite direction to previously reported findings as the CD27/CD45RA phenotype has been shown to mark the maturation and differentiation (TNa\uefve, TCentral-Memory, Teffector-Memory and TEffectory-Memory RA) of V\u3b42pos T cells. Indeed, the different surface expression of both CD27 and CD45 parallel the progressive decrease of telomere length, the proliferative capacity as well as the different effector-functions and resistance to death of V\u3b42+ T cells in response to antigens and homeostatic cytokines [4,5]. Hence, we believe that these controversial issues require further discussion beyond the unilateral conclusion given by the study of Weili Xu et al

Developing gene and cell therapies for rare diseases: An opportunity for synergy between academia and industry

For the last 20 years, academic research has been the major, and often only, driving force behind the spectacular development of gene transfer technology for the therapy of rare genetic diseases. Investors and industry became eventually interested in gene and cell therapy, due to the success of a series of pioneering clinical trials that proved efficacy and safety of last-generation technology, and to favorable orphan drug legislation in both Europe and the United States. Developing this forms of therapy is however complex and requires skills and knowledge not necessary available to the industry, which is better placed to develop processes and products and put them on the market. Cooperation between academia and industry is an opportunity to de-risk innovative approaches and ensure a faster and more economical development of therapies for diseases with high unmet medical needs and low-profit expectations

Interactions between Retroviruses and the Host Cell Genome

Replication-defective retroviral vectors have been used for more than 25 years as a tool for efficient and stable insertion of therapeutic transgenes in human cells. Patients suffering from severe genetic diseases have been successfully treated by transplantation of autologous hematopoietic stem-progenitor cells (HSPCs) transduced with retroviral vectors, and the first of this class of therapies, Strimvelis, has recently received market authorization in Europe. Some clinical trials, however, resulted in severe adverse events caused by vector-induced proto-oncogene activation, which showed that retroviral vectors may retain a genotoxic potential associated to proviral integration in the human genome. The adverse events sparked a renewed interest in the biology of retroviruses, which led in a few years to a remarkable understanding of the molecular mechanisms underlying retroviral integration site selection within mammalian genomes. This review summarizes the current knowledge on retrovirus-host interactions at the genomic level, and the peculiar mechanisms by which different retroviruses, and their related gene transfer vectors, integrate in, and interact with, the human genome. This knowledge provides the basis for the development of safer and more efficacious retroviral vectors for human gene therapy

Designing lentiviral vectors for gene therapy of genetic diseases

Lentiviral vectors are the most frequently used tool to stably transfer and express genes in the context of gene therapy for monogenic diseases. The vast majority of clinical applications involves an ex vivo modality whereby lentiviral vectors are used to transduce autologous somatic cells, ob-tained from patients and re-delivered to patients after transduction. Examples are hematopoietic stem cells used in gene therapy for hematological or neurometabolic diseases or T cells for immunotherapy of cancer. We review the design and use of lentiviral vectors in gene therapy of monogenic diseases, with a focus on controlling gene expression by transcriptional or post-transcriptional mechanisms in the context of vectors that have already entered a clinical development phase

Gene therapy of inherited skin adhesion disorders: a critical overview

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Chemotherapy accelerates immune-senescence and functional impairments of Vδ2pos T cells in elderly patients affected by liver metastatic colorectal cancer.

Human (gamma delta) γδ T cells are unconventional innate-like lymphocytes displaying a broad array of anti-tumor activities with promising perspectives in cancer immunotherapy. In this context, Vδ2pos T cells represent the preferential target of several immunotherapy protocols against solid tumors. However, the impact of both aging and chemotherapy (CHT) on Vδ2pos T cells is still unknown. The present study evaluates with multi-parametric flow cytometry the frequencies, terminal differentiation, senescence and effector-functions of peripheral blood and tumor infiltrating Vδ2pos T cells purified from liver metastases (CLM) of patients affected by colorectal cancer (CRC) compared to those of sex- and age-matched healthy donors. The peripheral blood of CLM patients underwent CHT is characterized by decreased amounts of Vδ2pos T cells showing a relative increase of terminally-differentiated CD27neg/CD45RApos (TEMRA) cells. The enrichment of this latter subset is associated with an increased expression of the senescent marker CD57. The acquisition of CD57 on TEMRA Vδ2pos T cells is also coupled with impairments in cytotoxicity and production of TNF-α and IFN-γ. These features resemble the acquisition of an immune-senescent profile by Vδ2pos T cells from CLM patients that received CHT, a phenomenon that is also associated with the loss of the co-stimulatory marker CD28 and with the induced expression of CD16. The group of CLM patients underwent CHT and older than 60 years old showed higher frequencies of CD57pos and TEMRA Vδ2pos T cells. Similar results were found for tumor infiltrating Vδ2pos T cell subset purified from CLM specimens of patients treated with CHT. The toxicity of CHT regimens also affects the homeostasis of Vδ2pos T cells by inducing higher frequencies of circulating CD57pos TEMRA subset in CLM underwent CHT and younger than 60 years old. Taken together, our data demonstrate that the enrichment of senescent Vδ2pos T cells in CLM patients is not only induced by patients' aging but also by the toxicity of CHT that further accelerates the accumulation of CD57pos TEMRA cells highly dysfunctional in their anti-tumor activities. These results are important to both predict the clinical outcome of CLM and to optimize those protocols of cell cancer immunotherapy employing unconventional Vδ2pos T cells

Hepatic natural killer cells: Organ-specific sentinels of liver immune homeostasis and physiopathology

The liver is considered a preferential tissue for NK cells residency. In humans, almost 50% of all intrahepatic lymphocytes are NK cells that are strongly imprinted in a liver-specific manner and show a broad spectrum of cellular heterogeneity. Hepatic NK (he-NK) cells play key roles in tuning liver immune response in both physiological and pathological conditions. Therefore, there is a pressing need to comprehensively characterize human he-NK cells to better understand the related mechanisms regulating their effector-functions within the dynamic balance between immune-tolerance and immune-surveillance. This is of particular relevance in the liver that is the only solid organ whose parenchyma is constantly challenged on daily basis by millions of foreign antigens drained from the gut. Therefore, the present review summarizes our current knowledge on he-NK cells in the light of the latest discoveries in the field of NK cell biology and clinical relevance

Bright expression of CD91 identifies highly activated human dendritic cells that can be expanded by defensins

CD91 is a scavenger receptor expressed by different immune cells and its ligands defensins have been demonstrated to contribute to immune responses against infections and tumors. We previously demonstrated that CD91 is expressed on human monocyte-derived dendritic cells (moDCs) and that human defensins stimulate in vitro the activation of these cells. In this study, we observed that CD91 is expressed at different levels on two distinct moDC subsets: CD91dim and CD91bright moDCs. Although CD91bright moDCs represented a small proportion of total moDCs, this subset showed higher levels of activation and maturation markers compared to CD91dim moDCs. The frequency of CD91bright moDCs increased by ~50% after in vitro stimulation with recombinant Human Neutrophil Peptide-1 (rHNP-1) and recombinant Human Beta Defensin-1 (rHBD-1), while lipopolysaccharide (LPS) stimulation decreased it by ~35%. Both defensins up-regulated moDC expression of CD80, CD40, CD83 and HLA-DR, although to a lower extent compared with LPS. Notably, upon culture with rHNP-1 and rHBD-1, CD91bright moDCs maintained their higher activation/maturation status, while this was lost upon culture with LPS. Our findings suggest that defensins promote the differentiation into activated CD91bright DCs and may encourage the exploitation of the CD91/defensins axis as a novel therapeutic strategy to potentiate antimicrobial and antitumor immune response

826. Transduction of Human Hematopoietic Stem Cells by RD114-TR-Pseudotyped Lentiviral Vectors

HIV-1-derived lentiviral vectors are efficiently pseudotyped by a chimeric envelope (RD114-TR) encoding the extracellular and transmembrane domains of the FLV RD114 glycoprotein fused to cytoplasmic tail (TR) of the MLV 4070A amphotropic glycoprotein. RD114-TR pseudotyped vectors may be concentrated by centrifugation, are resistant to complement inactivation, and are of particular interest for both ex vivo and in vivo gene therapy applications. We carried out a comparative analysis of VSV-G and RD114-TR-pseudotyped lentiviral vectors in transducing human cord blood-derived CD34+ hematopoietic stem/progenitor cells. Transduction efficiency was comparatively analysed in CD34+ cells in liquid culture, in the progeny of CD34+ clonogenic progenitors in semi-solid culture, and in the progeny of CD34+ repopulating stem cells after xeno-transplantation in NOD-SCID mice. In all cases, RD114-TR-pseudotyped vectors transduced hematopoietic cells at lower m.o.i., resulting in lower toxicity and more efficient stable transduction at comparable vector copy number per genome. Potential changes in CD34+ cells transcription profile and phenotype upon transduction with RD114-TR or VSV-G-pseudotyped vectors was investigated by Affymetrix Gene Chips microarray analysis. We found no significant difference in gene expression patterns between mock-RD114-TR and VSV-G-transduced cells. Our study show that the biology of repopulating hematopoietic stem cells and their progeny is not affected by transduction with RD114-TR-pseudotyped lentiviral vectors