Involvement of autologous myeloid dendritic cells in the evaluation of immediate hypersensitivity reactions to betalactams.

BACKGROUND: Amoxicillin (AX) and clavulanic acid (CLV) are the betalactam antibiotics (BLs) most used to treat bacterial infections, although they can trigger immediate hypersensitivity reactions (IDHRs). The maturation analysis of monocyte-derived dendritic cells (moDCs) and their capacity to induce proliferative response of lymphocytes are useful to test the sensitisation to a drug, although without optimal sensitivity. Nevertheless, this can be improved using directly isolated DCs such as myeloid DCs (mDCs). METHODS: mDCs and moDCs were obtained from 28 allergic patients (AP), 14 to AX, 14 to CLV and from 10 healthy controls (HC). The expression of CCR7, CD40, CD80, CD83, and CD86 was analysed after stimulation with both BLs. We measured the capacity of these pre-primed DCs to induce drug-specific activation of different lymphocyte subpopulations, CD3+, CD4+, CD8+, CD4+Th1, and CD4+Th2, by flow cytometry. RESULTS: Higher expression of CCR7, CD40, CD80, CD83, and CD86 was observed on mDCs compared to moDCs from AP after stimulating with the culprit BL. Similarly, mDCs induced higher proliferative response, mainly of CD4+Th2 cells, compared to moDCs, reaching up to 67% of positive results with AX, whereas of only 25% with CLV. CONCLUSIONS: mDCs from selective AP efficiently recognise the culprit drug which trigger the IDHR. mDCs also trigger proliferation of lymphocytes, mainly those with a Th2 cytokine pattern, although these responses depend on the nature of the drug, mimicking the patient's reaction.

Epigenetic targets to enhance antitumor immune response through the induction of tertiary lymphoid structures.

Tertiary lymphoid structures (TLS) are ectopic lymphoid aggregates found in sites of chronic inflammation such as tumors and autoimmune diseases. The discovery that TLS formation at tumor sites correlated with good patient prognosis has triggered extensive research into various techniques to induce their formation at the tumor microenvironment (TME). One strategy is the exogenous induction of specific cytokines and chemokine expression in murine models. However, applying such systemic chemokine expression can result in significant toxicity and damage to healthy tissues. Also, the TLS formed from exogenous chemokine induction is heterogeneous and different from the ones associated with favorable prognosis. Therefore, there is a need to optimize additional approaches like immune cell engineering with lentiviral transduction to improve the TLS formation in vivo. Similarly, the genetic and epigenetic regulation of the different phases of TLS neogenesis are still unknown. Understanding these molecular regulations could help identify novel targets to induce tissue-specific TLS in the TME. This review offers a unique insight into the molecular checkpoints of the different stages and mechanisms involved in TLS formation. This review also highlights potential epigenetic targets to induce TLS neogenesis. The review further explores epigenetic therapies (epi-therapy) and ongoing clinical trials using epi-therapy in cancers. In addition, it builds upon the current knowledge of tools to generate TLS and TLS phenotyping biomarkers with predictive and prognostic clinical potential.

Diagnosis of immediate reactions to amoxicillin: Comparison of basophil activation markers CD63 and CD203c in a prospective study.

BACKGROUND: Amoxicillin (AX) combined or not with clavulanic acid (CLV) is frequently involved in IgE-mediated reactions. Drug provocation test (DPT) is considered as the gold standard for diagnosis, although contraindicated in high-risk patients. Basophil activation test (BAT) can help diagnose immediate reactions to beta-lactams, although controversy exists regarding the best activation marker. We have performed a real-life study in a prospective cohort to analyze the real value of BAT as diagnostic tool and the best activation marker, CD63 and CD203c, for the evaluation of immediate reactions to these drugs. METHODS: We prospectively evaluated patients with a clinical suspicion of immediate reactions after AX or AX-CLV administration during a 6-year period. The allergological work-up was done following the EAACI recommendations. BAT was performed in all patients using CD63 and CD203c as activation markers. RESULTS: In AX-allergic patients, both activation markers, CD63 and CD203c, showed similar SE values (48.6% and 46.7%, respectively); however, specificity was of 81.1% and 94.6%, respectively, with CD203c showing good positive predictive value and like-hood ratio. In CLV-allergic patients, CD203c showed higher SE (50%) than CD63 (42.9%), maintaining the same value of SP (80%). Combining the results of both markers can slightly increase the sensitivity (51.4% for AX and 54.8% for CLV), although decreasing the specificity (79.7% and 73%, respectively). Interestingly, all patients with an anaphylactic shock showed a positive BAT to CLV using CD203c. CONCLUSIONS: BAT using CD203c showed a good confirmatory power, especially for AX allergy. Placing BAT as a first step in the diagnostic procedure can help reduce the need of performing a complete allergological work-up in 46.6% of patients, diminishing the risk of reinducing allergic reactions.

Technical challenges for complete implementation of automated growth-based methods for microbiological examination of advanced therapy medicinal products. What's wrong with Candida albicans?

BACKGROUND: Automated growth-based methods for sterility testing of cell-therapy products should be qualified to demonstrate that they are equivalent to, or better than, the conventional reference method. The aim of the present study was to assess the ability of the BACTEC FX40 system to detect low microbial contamination and to confirm the suitability of the method in the presence of seven different human mesenchymal cell-based products, according to Ph. Eur. 2.6.27. Additionally, a study to select the best vial to detect fungus contamination was performed. METHODS: Microorganisms representing Gram-negative, Gram-positive, aerobic, anaerobic, spore-forming, slow-growing bacteria, yeast and mold were prepared in either Dulbecco's PBS or seven biological matrices containing approximately 5, 10, and 15 colony-forming units (CFU) per sample. These preparations were inoculated to the specific media required for each test method: (i) BACTEC aerobic and anaerobic vials; (ii) aerobic and anaerobic media for direct inoculation; and (iii) Trypcase soy 3P or Brucella blood agar plates. Colonies from cultures were identified using MALDI-TOF mass spectrometry. RESULTS: The BACTEC FX40 system, in both Dulbecco's PBS and the biological matrices with a 5-CFU inoculum, detected most of the microorganisms significantly faster than the conventional method, despite the presence of a matrix containing gentamicin and several matrices containing 10% DMSO. Conversely, it showed an extremely delayed detection of Candida albicans compared with the conventional method. The addition of a Mycosis IC/F (MYC) vial decreased radically the time to detection (TTD) of C. albicans (28.2 ± 1.8 h) compared with the conventional method (36 h). CONCLUSIONS: When a MYC vial was added to the standard aerobic and anaerobic vials to test each sample, BACTEC FX40 was shown to be a superior alternative sterility method for cell-therapy products contaminated with low inocula, with a faster TTD for microbial growth compared with the conventional method (5 versus 14 days). The studies were carried out in different cell-based matrices with sensitivities and specificities of 100% for all the tested strains at 15-, 10- and 5-CFU inoculum, with the exception of Kocuria rhizophila at 5 CFU (90.48% sensitivity and 100% specificity).

The Evolution of Clinically Aggressive Triple-Negative Breast Cancer Shows a Large Mutational Diversity and Early Metastasis to Lymph Nodes.

In triple-negative breast cancer (TNBC), only 30% of patients treated with neoadjuvant chemotherapy achieve a pathological complete response after treatment and more than 90% die due to metastasis formation. The diverse clinical responses and metastatic developments are attributed to extensive intrapatient genetic heterogeneity and tumor evolution acting on this neoplasm. In this work, we aimed to evaluate genomic alterations and tumor evolution in TNBC patients with aggressive disease. We sequenced the whole exome of 16 lesions from four patients who did not respond to therapy, and took several follow-up samples, including samples from tumors before and after treatment, as well as from the lymph nodes and skin metastases. We found substantial intrapatient genetic heterogeneity, with a variable tumor mutational composition. Early truncal events were MCL1 amplifications. Metastatic lesions had deletions in RB1 and PTEN, along with TERT, AKT2, and CCNE1 amplifications. Mutational signatures 06 and 12 were mainly detected in skin metastases and lymph nodes. According to phylogenetic analysis, the lymph node metastases occurred at an early stage of TNBC development. Finally, each patient had three to eight candidate driving mutations for targeted treatments. This study delves into the genomic complexity and the phylogenetic and evolutionary development of aggressive TNBC, supporting early metastatic development, and identifies specific genetic alterations associated with a response to targeted therapies.

La biopsia líquida en el diagnóstico y monitoreo de pacientes oncológicos: Oportunidades y retos en Latinoamérica / Liquid biopsy in the diagnosis and monitoring of cancer patients: opportunities and challenges in Latin America

Resumen En los últimos años el estudio de los ácidos nucleicos circulantes ha tenido grandes avances en el campo de la oncología, lo que ha permitido avanzar de forma importante en las aplicaciones clínicas de la biopsia líquida en diferentes áreas como el pronóstico, la estadificación, la predicción de recurrencia, la selección y monitorización de tratamientos, entre otros. Lo anterior se debe en gran parte al desarrollo de nuevas y mejores tecnologías, algunas de las cuales incluso han sido autorizadas para el diagnóstico y seguimiento clínico de ciertos tipos de cáncer. No obstante, la utilización de la biopsia líquida como herramienta de apoyo clínico sigue siendo objeto de estudio. Debido a la importancia que ha cobrado este avance tecnológico a nivel mundial, se realizó una revisión de literatura con el fin de establecer el estado actual del uso de biopsia líquida en oncología, así como sus aplicaciones clínicas actuales, con un énfasis en Latinoamérica.

Abstract In recent years, the study of circulating nucleic acids has made great progress in the field of oncology, allowing for significant advances in clinical applications of liquid biopsy in diverse areas such as prognosis, staging, recurrence prediction, selection and monitoring of treatments, among others. This advance is largely due to the development of new and better technologies, some of which have even been validated for the diagnosis and clinical follow-up of certain types of cancer. However, the use of liquid biopsy as an additional tool in clinical oncology remains under study. Given the worldwide importance of this technological advance, a literature review was conducted to establish the current status of the use of liquid biopsy in oncology, as well as its current clinical applications, with a particular focus on Latin America.

Comprehensive Genomic Profile of Heterogeneous Long Follow-Up Triple-Negative Breast Cancer and Its Clinical Characteristics Shows DNA Repair Deficiency Has Better Prognostic.

Triple-negative breast cancer (TNBC) presents a marked diversity at the molecular level, which promotes a clinical heterogeneity that further complicates treatment. We performed a detailed whole exome sequencing profile of 29 Mexican patients with long follow-up TNBC to identify genomic alterations associated with overall survival (OS), disease-free survival (DFS), and pathologic complete response (PCR), with the aim to define their role as molecular predictive factors of treatment response and prognosis. We detected 31 driver genes with pathogenic mutations in TP53 (53%), BRCA1/2 (27%), CDKN1B (9%), PIK3CA (9%), and PTEN (9%), and 16 operative mutational signatures. Moreover, tumors with mutations in BRCA1/2 showed a trend of sensitivity to platinum salts. We found an association between deficiency in DNA repair and surveillance genes and DFS. Across all analyzed tumors we consistently found a heterogeneous molecular complexity in terms of allelic composition and operative mutational processes, which hampered the definition of molecular traits with clinical utility. This work contributes to the elucidation of the global molecular alterations of TNBC by providing accurate genomic data that may help forthcoming studies to improve treatment and survival. This is the first study that integrates genomic alterations with a long follow-up of clinical variables in a Latin American population that is an underrepresented ethnicity in most of the genomic studies.

AR-V7 as a Biomarker for Resistance to Treatment with Abiraterone/Enzalutamide in Three Latin American Countries: A Hypothetical Cost-Saving Analysis.

BACKGROUND: Prostate cancer is the most incident and one of the deadliest male cancers in Latin America. Treatment for patients with metastatic castration-resistant prostate cancer (mCRPC) includes androgen receptor signaling inhibitors such as abiraterone and enzalutamide, for which androgen receptor splice variant 7 (AR-V7) has emerged as a biomarker for primary resistance. Our study sought to analyze the potential economic impact of the use of AR-V7 detection as a treatment indicator in patients with mCRPC in three Latin American countries. MATERIALS AND METHODS: A hypothetical cost prediction model for the use of noninvasive circulating tumor cell-based AR-V7 testing as a treatment indicator for patients eligible for treatment with abiraterone/enzalutamide was conducted using available information on treatment and testing costs from Mexico, Argentina, and Colombia. RESULTS: At an estimated prevalence of AR-V7 positivity of 20%, the use of upfront AR-V7 genetic testing resulted in annual net savings of $9,801,669.97, $6,390,055.75, and $3,096,780.91 in Mexico, Argentina, and Colombia, respectively. A direct relationship between AR-V7 positivity prevalence and net savings was found. CONCLUSION: The use of a noninvasive AR-V7 detection assay as a treatment indicator tool in patients eligible for treatment with abiraterone or enzalutamide in Latin America could be a cost-effective approach for the management of these patients. Additional efforts are needed to accurately determine the incidence of castration-resistant prostate cancer cases and the prevalence of AR-V7 positivity in Latin America in order to predict the potential economic benefit of its clinical use. IMPLICATIONS FOR PRACTICE: In Latin America, prostate cancer is the most frequently diagnosed cancer in men, and the burden of this disease is expected to double in this region by 2030. Noninvasive detection of androgen receptor splice variant 7 (AR-V7) is being currently validated as a predictive biomarker for benefit with androgen receptor signaling inhibitor therapy in patients with metastatic castration-resistant prostate cancer (mCRPC). This hypothetical cost-saving analysis shows that AR-V7 testing in peripheral blood of patients with CRPC eligible for treatment with abiraterone or enzalutamide might represent a cost-effective strategy to select patients who will benefit from AR-axis-directed treatment in three Latin American countries.

Latin American Study of Hereditary Breast and Ovarian Cancer LACAM: A Genomic Epidemiology Approach.

Purpose: Hereditary Breast and Ovarian Cancer (HBOC) syndrome is responsible for ~5-10% of all diagnosed breast and ovarian cancers. Breast cancer is the most common malignancy and the leading cause of cancer-related mortality among women in Latin America (LA). The main objective of this study was to develop a comprehensive understanding of the genomic epidemiology of HBOC throughout the establishment of The Latin American consortium for HBOC-LACAM, consisting of specialists from 5 countries in LA and the description of the genomic results from the first phase of the study. Methods: We have recruited 403 individuals that fulfilled the criteria for HBOC from 11 health institutions of Argentina, Colombia, Guatemala, Mexico and Peru. A pilot cohort of 222 individuals was analyzed by NGS gene panels. One hundred forty-three genes were selected on the basis of their putative role in susceptibility to different hereditary cancers. Libraries were sequenced in MiSeq (Illumina, Inc.) and PGM (Ion Torrent-Thermo Fisher Scientific) platforms. Results: The overall prevalence of pathogenic variants was 17% (38/222); the distribution spanned 14 genes and varied by country. The highest relative prevalence of pathogenic variants was found in patients from Argentina (25%, 14/57), followed by Mexico (18%, 12/68), Guatemala (16%, 3/19), and Colombia (13%, 10/78). Pathogenic variants were found in BRCA1 (20%) and BRCA2 (29%) genes. Pathogenic variants were found in other 12 genes, including high and moderate risk genes such as MSH2, MSH6, MUTYH, and PALB2. Additional pathogenic variants were found in HBOC unrelated genes such as DCLRE1C, WRN, PDE11A, and PDGFB. Conclusion: In this first phase of the project, we recruited 403 individuals and evaluated the germline genetic alterations in an initial cohort of 222 patients among 4 countries. Our data show for the first time in LA the distribution of pathogenic variants in a broad set of cancer susceptibility genes in HBOC. Even though we used extended gene panels, there was still a high proportion of patients without any detectable pathogenic variant, which emphasizes the larger, unexplored genetic nature of the disease in these populations.

Comprehensive Analysis of Germline Variants in Mexican Patients with Hereditary Breast and Ovarian Cancer Susceptibility.

Hereditary breast and ovarian cancer syndrome (HBOC) represents 5⁻10% of all patients with breast cancer and is associated with high-risk pathogenic alleles in BRCA1/2 genes, but only for 25% of cases. We aimed to find new pathogenic alleles in a panel of 143 cancer-predisposing genes in 300 Mexican cancer patients with suspicion of HBOC and 27 high-risk patients with a severe family history of cancer, using massive parallel sequencing. We found pathogenic variants in 23 genes, including BRCA1/2. In the group of cancer patients 15% (46/300) had a pathogenic variant; 11% (33/300) harbored variants with unknown clinical significance (VUS) and 74% (221/300) were negative. The high-risk group had 22% (6/27) of patients with pathogenic variants, 4% (1/27) had VUS and 74% (20/27) were negative. The most recurrent mutations were the Mexican founder deletion of exons 9-12 and the variant p.G228fs in BRCA1, each found in 5 of 17 patients with alterations in this gene. Rare VUS with potential impact at the protein level were found in 21 genes. Our results show for the first time in the Mexican population a higher contribution of pathogenic alleles in other susceptibility cancer genes (54%) than in BRCA1/2 (46%), highlighting the high locus heterogeneity of HBOC and the necessity of expanding genetic tests for this disease to include broader gene panels.

Aseguramiento de Calidad en el Laboratorio de Biología Molecular: Control de Contaminación Ambiental / Quality Assurance in the Laboratory of Molecular Biology: Control of Environmental Contamination / Garantia de Qualidade no Laboratório de Biologia Molecular: Controle da Contaminação Ambiental

La reacción en cadena de la polimerasa (PCR) es la técnica más importante en Biología Molecular. Su principal deficiencia es la susceptibilidad a la contaminación de la muestra, ya sea con productos de amplificación generados en reacciones previas o con material genético proveniente de otras muestras. Se entiende por contaminación a la presencia indeseada de moléculas de ADN o ARN, que pueden actuar como templados en reacciones de amplificación. El objetivo del trabajo fue demostrar la importancia de la implementación de un control de contaminación ambiental periódico monitoreando la integridad del circuito de PCR. Para ello, se hisoparon puntos correspondientes a diferentes áreas de trabajo y se investigó la presencia de amplicones mediante PCR Real Time en Lighcycler 2.0, Roche® y Ampliprep Cobas s201, Roche®. En puntos críticos del circuito (flujo laminar o la cabina de seguridad del área de pre-PCR) no se detectaron amplicones, aunque sí se hallaron en las mesadas y heladeras. En el resto del circuito, la distribución de los amplicones fue variable. De esta forma se demuestra la importancia de la realización de un control de contaminación ambiental periódico en laboratorios que realizan la técnica de PCR, pudiendo detectar contaminación de forma precoz y tomar acciones correctivas a tiempo.

Polymerase chain reaction (PCR) is the most important technique in Molecular Biology. Its main deficiency is susceptibility to contamination of the sample, either with amplification products generated in previous reactions or with genetic material from other samples. Contamination is understood as the undesired presence of DNA or RNA molecules, which may act as annealing in amplification reactions. The objective of this work is to demonstrate the importance of implementing a periodic environmental pollution control by monitoring the integrity of the PCR. To do this, different areas of work were swabbed and the presence of amplicons were investigated by Real Time PCR in Lighcycler 2.0, Roche® and Ampliprep Cobas s201, Roche®. At critical points in the circuit (laminar flow or pre-PCR area booth) no amplicons were detected, although they were found in countertops and refrigerators. In the rest of the circuit, the distribution of the amplicons was variable. Thus, the importance of conducting a periodic environmental contamination control in laboratories that perform the PCR technique is demonstrated, enabling early detection contamination and corrective actions being taken on time.

A reação em cadeia da polimerase (PCR) é a técnica mais importante em Biologia Molecular. Sua principal deficiência é a suscetibilidade à contaminação da amostra, seja com produtos de amplificação gerados em reações prévias ou com material genético em reações prévias ou com material genético proveniente de outras amostras. Entende-se por contaminação a presença não desejada de moléculas de DNA ou ARN, que podem agir como temperados em reações de amplificação. O objetivo do trabalho foi demonstrar a importância da implementação de um controle de contaminação ambiental periódico monitorando a integridade do circuito de PCR. Para isso, se fez esfregaço de pontos correspondentes a diferentes áreas de trabalho e foi investigada a presença de amplicons mediante PCR Real Time em Lighcycler 2.0, Roche® e Ampliprep Cobas s201, Roche®. Em pontos críticos do circuito (fluxo laminar ou a cabine de segurança da área de pré-PCR), não foram detectados amplicons, apesar de serem encontrados nas bancadas e refrigeradores. No resto do circuito, a distribuição dos amplicons foi variável. Assim mostra a importância da realização de um controle de contaminação ambiental periódico em laboratórios que realizam a técnica de PCR, podendo detectar a contaminação de forma precoce e tomar ações corretivas a tempo.

Cancer Genomic Resources and Present Needs in the Latin American Region.

In Latin America (LA), cancer is the second leading cause of death, and little is known about the capacities and needs for the development of research in the field of cancer genomics. In order to evaluate the current capacity for and development of cancer genomics in LA, we collected the available information on genomics, including the number of next-generation sequencing (NGS) platforms, the number of cancer research institutions and research groups, publications in the last 10 years, educational programs, and related national cancer control policies. Currently, there are 221 NGS platforms and 118 research groups in LA developing cancer genomics projects. A total of 272 articles in the field of cancer genetics/genomics were published by authors affiliated to Latin American institutions. Educational programs in genomics are scarce, almost exclusive of graduate programs, and only few are concerning cancer. Only 14 countries have national cancer control plans, but all of them consider secondary prevention strategies for early diagnosis, opportune treatment, and decreasing mortality, where genomic analyses could be implemented. Despite recent advances in introducing knowledge about cancer genomics and its application to LA, the region lacks development of integrated genomic research projects, improved use of NGS platforms, implementation of associated educational programs, and health policies that could have an impact on cancer care.

Measles virus envelope pseudotyped lentiviral vectors transduce quiescent human HSCs at an efficiency without precedent.

Hematopoietic stem cell (HSC)-based gene therapy trials are now moving toward the use of lentiviral vectors (LVs) with success. However, one challenge in the field remains: efficient transduction of HSCs without compromising their stem cell potential. Here we showed that measles virus glycoprotein-displaying LVs (hemagglutinin and fusion protein LVs [H/F-LVs]) were capable of transducing 100% of early-acting cytokine-stimulated human CD34+ (hCD34+) progenitor cells upon a single application. Strikingly, these H/F-LVs also allowed transduction of up to 70% of nonstimulated quiescent hCD34+ cells, whereas conventional vesicular stomatitis virus G (VSV-G)-LVs reached 5% at the most with H/F-LV entry occurring exclusively through the CD46 complement receptor. Importantly, reconstitution of NOD/SCIDγc-/- (NSG) mice with H/F-LV transduced prestimulated or resting hCD34+ cells confirmed these high transduction levels in all myeloid and lymphoid lineages. Remarkably, for resting CD34+ cells, secondary recipients exhibited increasing transduction levels of up to 100%, emphasizing that H/F-LVs efficiently gene-marked HSCs in the resting state. Because H/F-LVs promoted ex vivo gene modification of minimally manipulated CD34+ progenitors that maintained stemness, we assessed their applicability in Fanconi anemia, a bone marrow (BM) failure with chromosomal fragility. Notably, only H/F-LVs efficiently gene-corrected minimally stimulated hCD34+ cells in unfractionated BM from these patients. These H/F-LVs improved HSC gene delivery in the absence of cytokine stimulation while maintaining their stem cell potential. Thus, H/F-LVs will facilitate future clinical applications requiring HSC gene modification, including BM failure syndromes, for which treatment has been very challenging up to now.

Expression of the epidermodysplasia verruciformis-associated genes EVER1 and EVER2 is activated by exogenous DNA and inhibited by LMP1 oncoprotein from Epstein-Barr virus.

EVER1 and EVER2 are mutated in epidermodysplasia verruciformis patients, who are susceptible to human betapapillomavirus (HPV) infection. It is unknown whether their products control the infection of other viruses. Here, we show that the expression of both genes in B cells is activated immediately after Epstein-Barr virus (EBV) infection, whereas at later stages, it is strongly repressed via activation of the NF-κB signaling pathway by latent membrane protein 1 (LMP1). Ectopic expression of EVER1 impairs the ability of EBV to infect B cells.

Baboon envelope pseudotyped LVs outperform VSV-G-LVs for gene transfer into early-cytokine-stimulated and resting HSCs.

Hematopoietic stem cell (HSC)-based gene therapy holds promise for the cure of many diseases. The field is now moving toward the use of lentiviral vectors (LVs) as evidenced by 4 successful clinical trials. These trials used vesicular-stomatitis-virus-G protein (VSV-G)-LVs at high doses combined with strong cytokine-cocktail stimulation to obtain therapeutically relevant transduction levels; however, they might compromise the HSC character. Summarizing all these disadvantages, alternatives to VSV-G-LVs are urgently needed. We generated here high-titer LVs pseudotyped with a baboon retroviral envelope glycoprotein (BaEV-LVs), resistant to human complement. Under mild cytokine prestimulation to preserve the HSC characteristics, a single BaEV-LV application at a low dose, resulted in up to 90% of hCD34(+) cell transduction. Even more striking was that these new BaEV-LVs allowed, at low doses, efficient transduction of up to 30% of quiescent hCD34(+) cells, whereas high-dose VSV-G-LVs were insufficient. Importantly, reconstitution of NOD/Lt-SCID/γc(-/-) (NSG) mice with BaEV-LV-transduced hCD34(+) cells maintained these high transduction levels in all myeloid and lymphoid lineages, including early progenitors. This transduction pattern was confirmed or even increased in secondary NSG recipient mice. This suggests that BaEV-LVs efficiently transduce true HSCs and could improve HSC-based gene therapy, for which high-level HSC correction is needed for life-long cure.

Epstein-Barr virus down-regulates tumor suppressor DOK1 expression.

The DOK1 tumor suppressor gene encodes an adapter protein that acts as a negative regulator of several signaling pathways. We have previously reported that DOK1 expression is up-regulated upon cellular stress, via the transcription factor E2F1, and down-regulated in a variety of human malignancies due to aberrant hypermethylation of its promoter. Here we show that Epstein Barr virus (EBV) infection of primary human B-cells leads to the down-regulation of DOK1 gene expression via the viral oncoprotein LMP1. LMP1 alone induces recruitment to the DOK1 promoter of at least two independent inhibitory complexes, one containing E2F1/pRB/DNMT1 and another containing at least EZH2. These events result in tri-methylation of histone H3 at lysine 27 (H3K27me3) of the DOK1 promoter and gene expression silencing. We also present evidence that the presence of additional EBV proteins leads to further repression of DOK1 expression with an additional mechanism. Indeed, EBV infection of B-cells induces DNA methylation at the DOK1 promoter region including the E2F1 responsive elements that, in turn, lose the ability to interact with E2F complexes. Treatment of EBV-infected B-cell-lines with the methyl-transferase inhibitor 5-aza-2'-deoxycytidine rescues DOK1 expression. In summary, our data show the deregulation of DOK1 gene expression by EBV and provide novel insights into the regulation of the DOK1 tumor suppressor in viral-related carcinogenesis.

Lentiviral vectors displaying modified measles virus gp overcome pre-existing immunity in in vivo-like transduction of human T and B cells.

Gene transfer into quiescent T and B cells is important for gene therapy and immunotherapy approaches. Previously, we generated lentiviral vectors (LVs) pseudotyped with Edmonston (Ed) measles virus (MV) hemagglutinin (H) and fusion (F) glycoproteins (H/F-LVs), which allowed efficient transduction of quiescent human T and B cells. However, a major obstacle in the use of H/F-LVs in vivo is that most of the human population is vaccinated against measles. As the MV humoral immune response is exclusively directed against the H protein of MV, we mutated the two dominant epitopes in H, Noose, and NE. LVs pseudotyped with these mutant H-glycoproteins escaped inactivation by monoclonal antibodies (mAbs) but were still neutralized by human serum. Consequently, we took advantage of newly emerged MV-D genotypes that were less sensitive to MV vaccination due to a different glycosylation pattern. The mutation responsible was introduced into the H/F-LVs, already mutated for Noose and NE epitopes. We found that these mutant H/F-LVs could efficiently transduce quiescent lymphocytes in the presence of high concentrations of MV antibody-positive human serum. Finally, upon incubation with total blood, mimicking the in vivo situation, the mutant H/F-LVs escaped MV antibody neutralization, where the original H/F-LVs failed. Thus, these novel H/F-LVs offer perspectives for in vivo lymphocyte-based gene therapy and immunotherapy.

A novel lentiviral vector targets gene transfer into human hematopoietic stem cells in marrow from patients with bone marrow failure syndrome and in vivo in humanized mice.

In vivo lentiviral vector (LV)-mediated gene delivery would represent a great step forward in the field of gene therapy. Therefore, we have engineered a novel LV displaying SCF and a mutant cat endogenous retroviral glycoprotein, RDTR. These RDTR/SCF-LVs outperformed RDTR-LVs for transduction of human CD34(+) cells (hCD34(+)). For in vivo gene therapy, these novel RDTR/SCF-displaying LVs can distinguish between the target hCD34(+) cells of interest and nontarget cells. Indeed, they selectively targeted transduction to 30%-40% of the hCD34(+) cells in cord blood mononuclear cells and in the unfractionated BM of healthy and Fanconi anemia donors, resulting in the correction of CD34(+) cells in the patients. Moreover, RDTR/SCF-LVs targeted transduction to CD34(+) cells with 95-fold selectivity compared with T cells in total cord blood. Remarkably, in vivo injection of the RDTR/SCF-LVs into the BM cavity of humanized mice resulted in the highly selective transduction of candidate hCD34(+)Lin(-) HSCs. In conclusion, this new LV will facilitate HSC-based gene therapy by directly targeting these primitive cells in BM aspirates or total cord blood. Most importantly, in the future, RDTR/SCF-LVs might completely obviate ex vivo handling and simplify gene therapy for many hematopoietic defects because of their applicability to direct in vivo inoculation.

In vivo gene delivery into hCD34+ cells in a humanized mouse model.

In vivo targeted gene delivery to hematopoietic stem cells (HSCs) would mean a big step forward in the field of gene therapy. This would imply that the risk of cell differentiation and loss of homing/-engraftment is reduced, as there is no need for purification of the target cell. In vivo gene delivery also bypasses the issue that no precise markers that permit the isolation of a primitive hHSC exist up to now. Indeed, in vivo gene transfer could target all HSCs in their stem-cell niche, including those cells that are "missed" by the purification criteria. Moreover, for the majority of diseases, there is a requirement of a minimal number of gene-corrected cells to be reinfused to allow an efficient long-term engraftment. This requisite might become a limiting factor when treating children with inherited disorders, due to the low number of bone marrow (BM) CD34(+) HSCs that can actually be isolated. These problems could be overcome by using efficient in vivo HSC-specific lentiviral vectors (LVs). Additionally, vectors for in vivo HSC transduction must be specific for the target cell, to avoid vector spreading while enhancing transduction efficiency. Of importance, a major barrier in LV transduction of HSCs is that 75% of HSCs are residing in the G0 phase of the cell cycle and are not very permissive for classical VSV-G-LV transduction. Therefore, we engineered "early-activating-cytokine (SCF or/and TPO)" displaying LVs that allowed a slight and transient stimulation of hCD34(+) cells resulting in efficient lentiviral gene transfer while preserving the "stemness" of the targeted HSCs. The selective transduction of HSCs by these vectors was demonstrated by their capacity to promote selective transduction of CD34(+) cells in in vitro-derived, long-term culture-initiating cell colonies and long-term NOD/SCID repopulating cells. A second generation of these "early-acting-cytokine"-displaying lentiviral vectors has now been developed that is fit for targeted in vivo gene delivery to hCD34(+) cells. In the method presented here, we describe the in vivo gene delivery into hCD34(+) cells by intramarrow injection of these new vectors into humanized BALB/c Rag2( null )/IL2rgc ( null ) (BALB/c RAGA) mice.