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.

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.

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.

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.

Abstract 1240: Comprehensive analysis of germline variants in Mexican patients with hereditary breast and ovarian cancer susceptibility

Hereditary breast and ovarian cancer syndrome (HBOC) is an autosomal dominant disease that represents approximately 5-10% of all patients with breast cancer. This syndrome is mainly associated to high-risk pathogenic alleles in BRCA1 and BRCA2 genes, but only for 25% of HBOC cases. This work aimed to find new pathogenic alleles in a panel of 143 cancer-predisposing genes in 300 Mexican cancer patients with suspicion of HBOC and 31 non-cancer patients with a severe family history of cancer, using massive parallel sequencing. We found 15% (45/300) patients with pathogenic variants in the group of cancer patients; 12% (35/300) harbored variants with unknown clinical significance (VUS) and 73% (220/300) were negative. The non-cancer group had a 32% (10/31) of patients with pathogenic variants, 3% (1/31) had VUS and 65% (20/31) were negative. Moreover, the most recurrent mutation was the Mexican founder deletion of exons 9-12 in BRCA1, found in 5 of 16 cancer patients with alterations in this gene. Private or rare VUS variants with potential impact at protein level were found in 22 genes, being CHEK2 the one with most VUS (6/39). Noteworthy, our results show for the first time in the Mexican population an equal contribution of pathogenic alleles in other susceptibility cancer genes (50%) as in BRCA1/2 (50%). This highlights the high locus heterogeneity of HBOC and the necessity of expanding genetic tests for this disease to broader gene panels. Further studies need to be conducted to define the clinical impact of the pathogenic alleles and VUS identified.

Citation Format: Felipe Vaca-Paniagua, Rosalía Quezada-Urban, Clara E. Díaz-Velásquez, Rina Gitler, María P. Rojo-Castillo, Max Sirota-Toporek, Andrea Figueroa-Morales, Oscar Moreno-García, Lizbeth García Esquivel, Gabriela Torres-Mejía, Michael Dean, Ivan Delgado-Enciso, Héctor Ochoa-Díaz-López, Fernando Rodriguez-León, Virginia Jan, Victor H. Hugo Garzón-Barrientos, Pablo Ruiz-Flores, Perla K. Espino-Silva, Jorge Haro-Santa Cruz, Héctor Martínez-Gregorio, Ernesto Rojas-Jiménez, Rosa M. Álvarez-Gómez, Luis A. Herrera, Isabelle Romieu, Luis I. Terrazas, Yolanda I. Chirino, Cecilia Frecha, Javier Oliver, Sandra Perdomo. Comprehensive analysis of germline variants in Mexican patients with hereditary breast and ovarian cancer susceptibility [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1240.

Abstract 1245: Identification of germline variants in cancer susceptibility genes in patients with hereditary breast and ovarian cancer syndrome by massive parallel sequencing in Argentinean population

Breast cancer is the most frequent cancer and ovarian cancer the seventh most frequent cancer among females worldwide, representing approximately 25% and 4% of all cancers. In Argentina, breast cancer and Ovarian cancer cause 6163 and 1332 deaths per year, respectively. Both breast and ovarian cancers are heterogeneous diseases composed of different tumor types with distinctive features and behaviors. The main risk factors for breast and ovarian cancer include age, family history, and genetics.The genetic components of both of the diseases have been well established, contributing to up to 10% of all breast cancer cases and 15% of all ovarian cancer cases.The two major susceptibility genes for both diseases are BRCA1 and BRCA2, and several other susceptibility genes have been identified. However, in the majority of high-risk breast and/or ovarian cancer (HBOC) families, the genetic predisposition factors remain unidentified, making the genetic counseling of these families challenging. The aim of the current study is to utilize an NGS approach to identify genetic factors that predispose individuals to hereditary breast and/or ovarian cancer (HBOC) in the high-risk Argentinian BRCA1/2 mutation-negative HBOC patients.16 patients were analyzed, the DNA was extracted from a blood samples and was subjected to a targeted massively parallel sequencing platform comprising 141 cancer predisposition genes. We detected in these patient 6 pathogenic variants in SBDS, FANCA, MC1R, WRN, MSR1 and SDHD genes. The effect of these variants are of type: non-synonymous (67%) and stop codon gains (33%). We also found 6 variants of uncertain significance (VUS) in APC, RAD50, SDHB, FANCD2, MLH1 and CDH1 genes.In conclusion, the identification of new variants could help to discover new genes associated to HBOC in the population of Argentina.These findings provide an excellent premise for further studies and could be utilized in the design of more efficient clinical management strategies for HBOC.

Citation Format: Alejandra Franco, Fernando Orti, Sandra Perdomo, Cecilia Riggi, Cecilia Frecha, Javier Oliver. Identification of germline variants in cancer susceptibility genes in patients with hereditary breast and ovarian cancer syndrome by massive parallel sequencing in Argentinean population [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1245.

Abstract 3263: Is Latin America ready for the use of genomics in cancer care and control

In Latin American (LA) countries cancer is the second most frequent cause of death after cardiovascular disease. Disease patterns have changed from infectious to chronic, the population is increasing and becoming elderly, and countries lack planning to respond adequately to this epidemiological and socio-demographic transition. By 2025 and increment of nearly 30% of new cases and 35% of deaths from cancer are predicted. Genomic studies have profoundly changed cancer management from improved cancer diagnosis to reformulating cancer prognosis and treatment. However, all these key advances have been mainly concentrated in highly developed nations and little is known about the capacities and needs of cancer genomics in the LA context. In order to evaluate the capacity and development of cancer genomics in LA, we collected available information for all countries in Central, South America and Cuba. Data reviewed included: number of NGS platforms, number of cancer research institutions, research groups working in cancer genetics, publications on cancer genetics and genomics in the last 10 years, educational programs on genomics and related national cancer control policies. Currently, there are a total of 212 NGS platforms in LA. Mexico and Brazil are the countries with more users, and Peru and Ecuador have the fewest. 118 research groups in South America have been working in cancer genetics and started developing cancer genomics related projects. No data on research groups was available for countries in Central America. In the last 10 years, 231 articles in cancer genetic/genomic related topics were published by authors affiliated to LA institutions. Educational programs in genomics are scarce, almost exclusive of graduate programs and few applied to cancer. Twelve countries in LA have national cancer control plans (NCCP). All NCCPs reviewed consider secondary prevention strategies for early diagnosis, opportune treatment and decrease of mortality, areas where genomic analysis could be implemented. Only 5 NCCPs include cancer research as an action plan to increase cancer prevention strategies and reduce both incidence and mortality. Despite the recent advances in introducing cancer genomics knowledge and application in LA, the region lacks development of integrated genomic research projects, improved use of platforms, associated educational programs and health policies that might focus on the most frequent cancers and could impact cancer care.

Citation Format: Sandra Perdomo, Angela Torres, Javier Olivier, Cecilia Frecha, Rosalía Quezada-Urban, Clara Estela Díaz-Velasquez, Felipe Vaca. Is Latin America ready for the use of genomics in cancer care and control [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3263. doi:10.1158/1538-7445.AM2017-3263

Cytokines Mediating Inflammation in a Model of Secondary Immunodeficiency in Wistar Rats: Immunomodulation Triggered by Thymomodulin

We have previously demonstrated in a rat model of immunodeficiency, an increase in the number of γδ T cells in the gut lamina propria and in the number of CD8αα+, CD25+, γδ+ subpopulations of intestinal intraepithelial lymphocytes (iIEL). The increased percentage of CD8αα+ iIEL that express CD25 indicates inflammation. The present study confirms the existence of an inflammatory process in the immunodeficient animals (R21) that is not detectable at the histological level but is characterized by an increase of the pro-inflammatory cytokines TNF-α and IFN-γ. We have shown a direct relationship between TNF receptor II (TNF-RII) expression and the higher levels of the γδ+ iIEL expressing TNF-α (TCRγδ+/TNF-α+ cells) that could be indicating a differential T cell reactivity. The effects of the increased expression of inflammatory cytokines such as TNF-α and INF-γ seem to be down regulated by the high levels of antigen specific TGF-β expression, which, we believe, is antigen specific and appears to maintain oral tolerance. Finally, in malnourished animals NF-κB remains principally in the cytosol and is unable to translocate to the nucleus, indicating the existence of alterations in the metabolic pathways leading to nuclear factor κB translocation from the cytoplasm to the nucleus. The therapeutic action of the immunomodulator TmB was demonstrated by its capacity to return all the cytokines studied to control levels. Moreover, its effects allowed the transcription factor NF-κB to translocate to the nucleus from the cytosol.

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.

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.

Was cDNA sequences modulate transgene expression of was promoter-driven lentiviral vectors

Abstract The development of vectors that express a therapeutic transgene efficiently and specifically in hematopoietic cells (HCs) is an important goal for gene therapy of hematological disorders. We have previously shown that a 500-bp fragment from the proximal Was gene promoter in a lentiviral vector (LV) was sufficient to achieve more than 100-fold higher levels of Wiskott-Aldrich syndrome protein in HCs than in nonhematopoietic cells (non-HCs). We show now that this differential was reduced up to 10 times when the enhanced green fluorescent protein gene (eGFP) was expressed instead of Was in the same LV backbone. Insertion of Was cDNA sequences downstream of eGFP in these LVs had a negative effect on transgene expression. This effect varied in different cell types but, overall, Was cDNA sequences increased the hematopoietic specificity of Was promoter-driven LV. We have characterized the minimal fragment required to increase hematopoietic specificity and have demonstrated that the mechanism involves Was promoter regulation and RNA processing. In addition, we have shown that Was cDNA sequences interfere with the enhancer activity of the woodchuck posttranscriptional regulatory element. These results represent the first data showing the role of Was intragenic sequences in gene regulation.

Advances in the field of lentivector-based transduction of T and B lymphocytes for gene therapy

Efficient gene transfer into quiescent T and B lymphocytes for gene therapy or immunotherapy purposes may allow the treatment of several genetic dysfunctions of the hematopoietic system, such as immunodeficiencies, and the development of novel therapeutic strategies for cancers and acquired diseases. Lentiviral vectors (LVs) can transduce many types of nonproliferating cells, with the exception of some particular quiescent cell types such as resting T and B cells. In T cells, completion of reverse transcription (RT), nuclear import, and subsequent integration of the vesicular stomatitis virus G protein pseudotyped LV (VSVG-LV) genome does not occur efficiently unless they are activated via the T-cell receptor (TCR) or by survival-cytokines inducing them to enter into the G(1b) phase of the cell cycle. Lentiviral transduction of B cells is another matter because even B-cell receptor-stimulation inducing proliferation is not sufficient to allow efficient VSVG-LV transduction. Recently, a new LV carrying the glycoproteins of measles virus (MV) at its surface was able to overcome vector restrictions in both quiescent T and B cells. Importantly, naive as well as memory T and B cells were efficiently transduced while no apparent activation, cell-cycle entry, or phenotypic switch were detected, which opens the door to a multitude of gene therapy and immunotherapy applications as reported here.

Strategies for targeting lentiviral vectors

Vectors derived from retroviruses such as lentiviruses and onco-retroviruses are probably among the most suitable tools to achieve a long-term gene transfer since they allow stable integration of a transgene and its propagation in daughter cells. Lentiviral vectors should be preferred gene delivery vehicles over vectors derived from onco-retroviruses (MLV) since in contrast to the latter they can transduce non-proliferating target cells. Moreover, lentiviral vectors that have the capacity to deliver transgenes into specific tissues are expected to be of great value for various gene transfer approaches in vivo. Here we provide an overview of innovative approaches to upgrade lentiviral vectors for tissue or cell targeting and which have potential for in vivo gene delivery. In this overview we distinguish between three types of lentiviral vector targeting strategies (Fig 1): 1) targeting of vectors at the level of vector-cell entry through lentiviral vector surface modifications; 2) targeting at the level of transgene transcription by insertion of tissue specific promoters into lentiviral vectors; 3) a novel microRNA technology that rather than targeting the 'right' cells will 'detarget' transgene expression from non-target cells while achieving high expression in the target-cell. It is clear that each strategy is of enormous value for several gene therapy approaches but combining these three layers of transgene expression control will offer tools to really overcome several drawbacks in the field such as side-effect of off-target expression, clearance of transgene modified cells by immune response to the transgene and lack of biosecurity and efficiency in in vivo approaches.

Hematopoietic-specific lentiviral vectors circumvent cellular toxicity due to ectopic expression of Wiskott-Aldrich syndrome protein

Efficient and safe gene modification of hematopoietic stem cells is a requirement for gene therapy of primary immunodeficiencies such as Wiskott-Aldrich syndrome. However, deregulated expression or ectopic expression in the progeny of transduced nonhematopoietic progenitor cells may lead to unwanted toxicity. We therefore analyzed the effect of ectopic expression of Wiskott-Aldrich syndrome protein (WASp) and the potential benefits of hematopoietic-specific lentiviral vectors (driven by the WAS proximal promoter). Overexpression of WASp by constitutive lentiviral vectors is highly toxic in nonhematopoietic cells because it causes dramatic changes in actin localization and polymerization that result in decreased cell viability, as evidenced by a significant growth disadvantage of WASp-overexpressing nonhematopoietic cells and increased cell death. These toxic effects do not affect cells of hematopoietic origin because, remarkably, we found that WASp cannot be readily overexpressed in T cells, even after multiple vector integrations per cell. The adverse cellular effects found after transduction of nonhematopoietic cells with constitutive lentiviral vectors are overcome by the use of transcriptionally targeted lentiviral vectors expressing WASp, which, at the same time, are efficient tools for gene therapy of WAS as demonstrated by their ability to reconstitute cellular defects from WASp-deficient mouse and human cells. We therefore postulate that transcriptionally regulated lentiviral vectors represent a safer and efficient alternative for the development of clinical protocols of WAS gene therapy.

Transplantation of human CD34+ stem cells from umbilical cord blood to rats with thioacetamide-induced liver cirrhosis

BACKGROUND

Liver fibrosis results from accumulation of extracellular matrix components and is associated with many chronic hepatic diseases. There is to date no specific therapy for this disease, and patients receive treatment for its associated complications. Specific progenitor cells, known as oval cells, are present in the liver. As oval cells express markers such as CD34, they are thought to arise from a hematopoietic precursor. The aim of this work was to investigate whether transplantation of hematopoietic CD34(+) stem cells could improve hepatic fibrosis by their differentiation into hepatocytes.

METHODS

CD34(+) stem cells from human umbilical cord blood were purified, transduced with a lentiviral vector containing the green fluorescent protein (GFP) gene and injected via portal vein into rats with liver cirrhosis induced by the 4-month administration of thioacetamide. Rats were killed 15 and 60 days post-transplantation.

RESULTS

Up to 37% and 22% fluorescent cells were observed in the blood of control and cirrhotic rats, respectively, at 15 days post-transplantation. At 60 days post-transplantation, however, fluorescent cells were completely absent from the blood. Fluorescence was not detected in liver sections at either 15 or 60 days post-transplantation. Polymerase chain-reaction study to detect the GFP gene ruled out silencing of the transgene.

CONCLUSIONS

These results suggest that the transplanted cells did not engraft in the liver and were eliminated from the rats.

Follicular dendritic cells are related to bone marrow stromal cell progenitors and to myofibroblasts

Follicular dendritic cells (FDC) are involved in the presentation of native Ags to B cells during the secondary immune response. Some authors consider FDC to be hemopoietic cells, whereas others believe them to be mesenchymal cells. The low proportion of FDC in the lymphoid follicle, together with technical difficulties in their isolation, make these cells difficult to study. We show that Fibroblast Medium can be used successfully to isolate and maintain FDC lines. In this culture medium, we obtained 18 FDC lines from human tonsils, which proliferated for as long as 18 wk and showed a stable Ag phenotype as detected by flow cytometry and RT-PCR. FDC lines were CD45-negative and expressed Ags associated to FDC (CD21, CD23, CD35, CD40, CD73, BAFF, ICAM-1, and VCAM-1) and Ags specific for FDC (DRC-1, CNA.42, and HJ2). These cell lines were also able to bind B cells and secrete CXCL13, functional activities characteristic of FDC. Nevertheless, the additional expression of STRO-1, together with CD10, CD13, CD29, CD34, CD63, CD73, CD90, ICAM-1, VCAM-1, HLA-DR, alkaline phosphatase, and alpha-smooth muscle actin (alpha-SM actin) indicated that FDC are closely related to bone marrow stromal cell progenitors. The expression of alpha-SM actin also relates FDC with myofibroblasts. Like myofibroblasts, FDC lines expressed stress fibers containing alpha-SM actin and were able to contract collagen gels under the effect of TGFbeta1 and platelet-derived growth factor. These findings suggest that FDC are a specialized form of myofibroblast and derive from bone marrow stromal cell progenitors.

A novel Wiskott-Aldrich syndrome protein (WASP) complex mutation identified in a WAS patient results in an aberrant product at the C-terminus from two transcripts with unusual polyA signals

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by immunodeficiency, thrombocytopenia and eczema. A broad spectrum of mutations in the WASP gene has been identified as causing the disease. In the present paper, we report on a patient affected by WAS with a novel complex mutation, characterized by a small 9 bp deletion followed by an inversion of 151 bp and a gross deletion of 4.3 kb within the Xp11.23 region. The small deletion and the inverted fragment are found in intron 11. The large deletion initiates downstream of exon 11 of the WASP gene, including exon 12, and a genomic region upstream of the promoter of the contiguous SUV39H1 gene. Expression studies of the mRNA of the patient's sample showed the presence of two aberrant transcripts that code for a protein of 519 amino acids. We demonstrate that these two transcripts differ in the 3' UTR region, and result from the use of two alternative polyadenylation signals. The severe phenotype of the patient correlates with the presence of an aberrant protein.

Lentiviral vectors transcriptionally targeted to hematopoietic cells by WASP gene proximal promoter sequences

The development of vectors that express a therapeutic transgene efficiently and specifically in hematopoietic cells (HCs) is an important goal for gene therapy of hematological disorders. In order to achieve this, we used a 500 bp fragment from the proximal WASP gene promoter to drive the expression of the WASP cDNA in the context of a self-inactivating lentiviral vector. Single-round transduction of WASp-deficient herpesvirus saimiri (HVS)-immortalized cells as well as primary allospecific T cells from Wiskott-Aldrich syndrome (WAS) patients with this vector (WW) resulted in expression levels similar to those of control cells. Non-HCs were transduced with similar efficiency, but the levels of WASp were 135-350 times lower than those achieved in HCs. Additionally, transduction of WASp-deficient cells with WW conferred a selective growth advantage in vitro. Therefore, lentiviral vectors incorporating proximal promoter sequences from the WASP gene confer hematopoietic-specific, and physiological protein expression.

Efficient lentiviral transduction of Herpesvirus saimiri immortalized T cells as a model for gene therapy in primary immunodeficiencies

Infection of human T lymphocytes with the Herpesvirus saimiri (HVS) yields immortalized T-cell lines (HVS-T) which retain all the phenotypical and functional characteristics of their parental cells. This represents a new experimental model for studying genetic disorders of T lymphocytes. In spite of the efforts of many laboratories, no satisfactory way has been found so far to modify HVS-T cells genetically. We have analyzed the capacity of oncoretroviral (MLV)- and lentiviral (HIV-1)-based vectors pseudotyped with vesicular stomatitis virus glycoprotein (VSVg) to transduce HVS-T cells. HIV-1-derived vectors efficiently transduced HVS-T cell lines, reaching up to 85% of cells expressing the transgene in a single round of infection. MLV-based vectors, on the other hand, were unable to transduce more than 1% of any of the HVS-T cell lines analyzed. Lentiviral-driven gene expression was maintained constant and stable in HVS-T cells for a minimum of 48 days. We also observed that although the lentiviral transduction efficiency achieved on HVS-T cells is lower than that obtained with tumor or primary endothelial cells, it is nevertheless similar to that found with activated primary T cells.