Clinical impact of NK-cell reconstitution after reduced intensity conditioned unrelated cord blood transplantation in patients with acute myeloid leukemia: analysis of a prospective phase II multicenter trial on behalf of the Société Française de Greffe de Moelle Osseuse et Thérapie Cellulaire and Eurocord

Unrelated cord blood transplantation (UCBT) after a reduced intensity conditioning regimen (RIC) has extended the use of UCB in elderly patients and those with co-morbidities without an HLA-identical donor, although post-transplant relapse remains a concern in high-risk acute myeloid leukemia (AML) patients. HLA incompatibilities between donor and recipient might enhance the alloreactivity of natural killer (NK) cells after allogeneic hematopoietic stem-cell transplantation (HSCT). We studied the reconstitution of NK cells and KIR-L mismatch in 54 patients who underwent a RIC-UCBT for AML in CR in a prospective phase II clinical trial. After RIC-UCBT, NK cells displayed phenotypic features of both activation and immaturity. Restoration of their polyfunctional capacities depended on the timing of their acquisition of phenotypic markers of maturity. The incidence of treatment-related mortality (TRM) was correlated with low CD16 expression (P=0.043) and high HLA-DR expression (P=0.0008), whereas overall survival was associated with increased frequency of NK-cell degranulation (P=0.001). These features reflect a general impairment of the NK licensing process in HLA-mismatched HSCT and may aid the development of future strategies for selecting optimal UCB units and enhancing immune recovery.

HLA-E upregulation on IFN-gamma-activated AML blasts impairs CD94/NKG2A-dependent NK cytolysis after haplo-mismatched hematopoietic SCT

Natural killer (NK) cells generated after haploidentical hematopoietic SCT in patients with AML are characterized by specific phenotypic features and impaired functioning that may affect transplantation outcome. We show that IFN-gamma produced by immature CD56(bright) NK cells upregulates cell surface expression of HLA-E on AML blasts and that this upregulation protects leukemic cells from NK-mediated cell lysis through the mediation of CD94/NKG2A, an inhibitory receptor overexpressed on NK cells after haploidentical SCT. Two years after transplantation, however, maturing NK cells were functionally active, as evidenced by high cytotoxicity and poor IFN-gamma production. This implies that maturation of NK cells is the key to improved immune responses and transplantation outcome.

Fully functional NK cells after unrelated cord blood transplantation

Promising results of umbilical cord blood transplantation (UCBT) from unrelated donors have been reported in patients with hematologic disorders. These transplants, having potential to trigger beneficial donor-versus-recipient natural killer (NK) cell-mediated alloreaction, we have conducted the first extensive analysis of the phenotypic and functional properties of NK cells after UCBT. NK cells from 25 patients with high-risk hematologic malignancies were compared with cells derived from both healthy adult and CB cells. We found that following UCBT, NK cells display not only some phenotypic features associated with maturity but also unique characteristics that make them fully functional against leukemic blasts. We propose that this full functionality of alloreactive donor-derived NK may drive graft-versus-leukemia reactions after UCBT.

Inhibition of human immunodeficiency virus transmission to CD4+ T cells after gene transfer of constitutively expressed interferon beta to dendritic cells

CD34(+)-derived dendritic cells (DCs) can be infected by the T cell-tropic HIVLAI strain, but are poorly permissive for efficient virus production. However, HIVLAI-infected DCs are able to transmit a vigorous cytopathic infection to activated CD4(+) T cells. We show that DCs differentiated from CD34(+) cells can be efficiently transduced by a retroviral vector carrying the IFN-beta coding sequence. This results in resistance to infection by HIV as shown by a threefold reduction in the HIV DNA copy number per cell, and by inhibition of HIV transmission from DCs to CD4(+) T cells. Moreover, constitutive IFN-beta production by DCs increases the synthesis of IL-12 and IFN-gamma Th1-type cytokines and of the beta-chemokines MIP-1alpha, MIP-1beta, and RANTES. This indicates that IFN-beta transduction of DCs blocks HIV infection and viral transmission to CD4(+) T cells, and could favor cellular immune responses in HIV-infected patients.

Retrovirally mediated IFN-beta transduction of macrophages induces resistance to HIV, correlated with up-regulation of RANTES production and down-regulation of C-C chemokine receptor-5 expression

Constitutive expression of IFN-beta by HIV target cells may be an alternative or complementary therapeutic approach for the treatment of AIDS. We show that macrophages derived from CD34+ cells from umbilical cord blood can be efficiently transduced by a retroviral vector carrying the IFN-beta coding sequence. This results in resistance to infection by a macrophage-tropic HIV type 1, as shown by the drastic reduction in the HIV DNA copy number per cell and in p24 release. Moreover, IFN-beta transduction totally blocked secretion of proinflammatory cytokines after HIV infection. The constitutive IFN-beta production also resulted in an increased production of IL-12 and IFN-gamma Th1-type cytokines and of the beta-chemokines macrophage-inflammatory protein-1alpha, macrophage-inflammatory protein-1beta, and RANTES. RANTES was found to be involved in the HIV resistance observed, and this was correlated with a down-regulation of the CCR-5 HIV entry coreceptor. These results demonstrate the feasibility and the efficacy of such IFN-beta-mediated gene therapy. In addition to inhibiting HIV replication, IFN-beta transduction could have beneficial immune effects in HIV-infected patients by favoring cellular immune responses.

Transfer of human CD4(+) T lymphocytes producing beta interferon in Hu-PBL-SCID mice controls human immunodeficiency virus infection

Beta interferon (IFN-beta) exerts pleiotropic antiretroviral activities and affects many different stages of the human immunodeficiency virus (HIV) infectious cycle in IFN-treated cells. To explore whether transfer of genetically engineered human CD4(+) T cells producing constitutively low amounts of IFN-beta can eradicate HIV in vivo, we developed a new Hu-PBL-SCID mouse model supporting a persistent, replicative HIV infection maintained by periodic reinoculations of activated human CD4(+) T cells. Transferring human CD4(+) T cells containing the IFN-beta retroviral vector drastically reduced the preexisting HIV infection and enhanced CD4(+) T-cell survival and Th1 cytokine expression. Furthermore, in 40% of the Hu-PBL-SCID mice engrafted with IFN-beta-transduced CD4(+) T cells, HIV-1 was undetectable in vivo as well as after cocultivation of mouse tissues with human phytohemagglutinin-stimulated lymphoblasts. These results indicate that a therapeutic strategy based upon IFN-beta transduction of CD4(+) T cells may be an approach to controlling a preexisting HIV infection and allowing immune restoration.

Cutting edge: RANTES regulates Fas ligand expression and killing by HIV-specific CD8 cytotoxic T cells

Based on the previous observation that RANTES mediates the cytotoxic activity of human HIV-specific CD8+ T cells via the chemokine receptor CCR3, we studied the effect of this chemokine on different effector CD8+ cytolytic cells requiring Fas/Fas ligand (FasL) or perforin-dependent pathway. In CTLs derived from PBMCs of HIV-infected patients, both the spontaneous and the RANTES-induced cytotoxicity were inhibited by anti-FasL neutralizing Abs. In contrast, allogeneic CTLs or NK cells killing through perforin were not affected by RANTES and anti-FasL Ab. Accordingly, RANTES enhanced the expression of FasL in a concentration- and time-dependent manner in HIV-specific CTLs, whereas anti-RANTES Ab decreased markedly FasL expression. Finally, cell surface expression of FasL protein in HIV-specific CTLs was also up-regulated by eotaxin, a selective ligand for CCR3. Our observations show that the action of RANTES via CCR3 is necessary to regulate FasL expression on HIV-specific CD8+ T cells that kill through the Fas/FasL pathway.

Acquired constitutive expression of interferon beta after gene transduction enhances human immunodeficiency virus type 1-specific cytotoxic T lymphocyte activity by a RANTES-dependent mechanism

CTL lines directed against HIV-1 antigens were generated from infected individuals and were transduced by the HMB-K(b)HuIFNbeta vector, resulting in low, constitutive expression of interferon beta (IFN-beta). The IFN-beta-transduced cells showed markedly increased HIV-1-specific, MHC class I-restricted CTL activity against HIV-1-LAI Gag, Pol, or Env antigens. This effect of IFN-beta was correlated with an overexpression of RANTES and completely abrogated by RANTES-blocking antibody. The present results provide the first evidence that IFN-beta transduction of CTL lines enhances HIV-specific cytotoxic activities through an upregulation of RANTES production. The efficient elimination of HIV-infected cells by IFN-beta-transduced CTL lines makes this gene therapy approach an attractive treatment for AIDS.

Interferon-beta-induced human immunodeficiency virus resistance in CD34(+) human hematopoietic progenitor cells: correlation with a down-regulation of CCR-5 expression

To explore the possibility of conferring a long-term resistance against human immunodeficiency virus (HIV) by a low continuous production of interferon-beta (IFN-beta) in hematopoietic progenitor cells, we transduced the human CD34(+) TF-1 cells with a retroviral vector ensuring IFN-beta production. The IFN-beta-transduction of TF-1 cells resulted in resistance to infection with HIV-LAI, as shown by the selective survival of IFN-beta-transduced CD4(+) cells and the protection against HIV-induced apoptosis. A similar response against HIV-LAI infection was obtained after pretreatment with 100 U/ml of recombinant IFN-alpha2b or IFN-beta. In contrast, after the addition of macrophage cell tropic (M cell-tropic) HIV strain, a treatment with exogenous IFN-alpha2b resulted in a >==10-fold lower protection compared with exogenous IFN-beta or IFN-beta transduction. This specific effect of IFN-beta on M cell-tropic HIV strains was correlated with a down-regulation of the CCR-5 chemokine receptor expression, corresponding to a novel antiviral effect of IFN-beta.

HIV-specific T cell cytotoxicity mediated by RANTES via the chemokine receptor CCR3

CC chemokines produced by CD8(+) T cells are known to act as HIV-suppressive factors. We studied the possible role of these chemokines in HIV-1-specific killing of target cells. We found that the activity of cytotoxic T lymphocytes (CTLs) in CTL lines or freshly isolated peripheral blood mononuclear cells from HIV-1-infected individuals is markedly enhanced by RANTES (regulated on activation, normal T cell expressed and secreted) and virtually abolished by an antibody neutralizing RANTES or the RANTES receptor antagonist RANTES(9-68). Lysis was mediated by CD8(+) major histocompatibility complex class I-restricted T cells and was obtained with target cells expressing epitopes of the HIV-1LAI proteins Gag, Pol, Env, and Nef. The cytolytic activity observed in the presence or absence of added RANTES could be abolished by pretreatment of the CTLs with pertussis toxin, indicating that the effect is mediated by a G protein-coupled receptor. The chemokines monocyte chemotactic protein (MCP)-3, MCP-4, and eotaxin acted like RANTES, whereas macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, MCP-1, and stromal cell-derived factor 1 were inactive, suggesting a role for the eotaxin receptor, CCR3, and ruling out the involvement of CCR1, CCR2, CCR5, and CXCR4. CTL activity was abrogated by an antibody that blocks CCR3, further indicating that specific lysis is triggered via this chemokine receptor. These observations reveal a novel mechanism for the induction of HIV-1-specific cytotoxicity that depends on RANTES acting via CCR3.

Interferon beta transduction of peripheral blood lymphocytes from HIV-infected donors increases Th1-type cytokine production and improves the proliferative response to recall antigens

We are developing a gene therapy method of HIV infection based on the constitutive low production of interferon (IFN) beta. Peripheral blood lymphocytes (PBL) from HIV-infected patients at different clinical stages of infection were efficiently transduced with the HMB-HbHuIFNbeta retroviral vector. The constitutive low production of IFN-beta in cultured PBL from HIV-infected patients resulted in a decreased viral production and an enhanced survival of CD4+ cells, and this protective effect was observed only in the PBL derived from donors having a CD4+ cell count above 200 per mm3. In IFN-beta-transduced PBL from healthy and from HIV-infected donors, the production of the Th1-type cytokines IFN-gamma and interleukin (IL)-12 was enhanced. In IFN-beta-transduced PBL from HIV-infected donors, the production of IL-4, IL-6, IL-10, and tumor necrosis factor alpha was maintained at normal levels, contrary to the increased levels produced by the untransduced PBL. The proliferative response to recall antigens was partially restored in IFN-beta-transduced PBL from donors with an impaired antigen response. Thus, in addition to inhibiting HIV replication, IFN-beta transduction of PBL from HIV-infected donors improves several parameters of immune function.

[Development of an anti-HIV gene therapy based on the antiviral properties of beta interferon]

The aim of our work is to explore the use of IFN-beta for gene therapy in the HIV-infection. Transduction of various HIV target cells with a retroviral vector that carries the Hu-IFN-beta coding sequence under constitutive low expression control, confers resistance to HIV without affecting cell replication or function. After transduction, lymphocytes from HIV-infected patients develop resistance to the endogenous virus, provided the cells are derived from individuals with a CD4 cell count higher than 200 per mm3.

Autocrine interferon-beta synthesis for gene therapy of HIV infection: increased resistance to HIV-1 in lymphocytes from healthy and HIV-infected individuals

OBJECTIVE

To explore the possibility of gene therapy of HIV infection based on the multiple antiretroviral activities of interferon (IFN)-beta.

DESIGN

We introduced into HIV target cells an IFN-beta gene placed under an expression control ensuring a low and constitutive expression, sufficient to confer a permanent antiviral state without impeding normal cell function.

METHODS

We transformed, with an efficacy ranging from 20-55%, peripheral blood lymphocytes (PBL) derived from healthy, seronegative donors, and from asymptomatic HIV-infected individuals by the HMB-KbHuIFN beta retroviral vector carrying the human IFN-beta coding sequence driven by a fragment of the murine H-2Kb gene promoter.

RESULTS

The replication rate of the IFN-beta-expressing cells was no different from that of untransformed controls during the 21-day period of in vitro observation. When IFN-beta-transformed, purified CD4+ lymphocytes from healthy donors were HIV-1LAI-infected, virus replication was inhibited and most of the cells survived, in contrast to untransformed CD4+ cells which were all destroyed 12 days after infection. Protection of CD4+ cells from the same donors was also observed in suspensions of IFN-beta-transformed total PBL that were infected with HIV-1LAI. In IFN-beta-transformed PBL from four HIV-infected donors, endogenous HIV replication was decreased and 28-69% of the CD4+ cells survived at the end of the 21 days in culture. In the untransformed control PBL suspensions, all CD4+ cells were destroyed. In long-term experiments, HIV-infected, IFN-beta-transformed cell populations of the lymphocytic CEM and the promonocytic U937 line were kept in culture for 60 days, during which time they remained resistant to HIV infection.

CONCLUSION

These results indicate that further exploration of autocrine IFN-beta production for somatic cell gene therapy of HIV infection is warranted.

Stable antiviral expression (SAVE) as an approach to somatic cell gene therapy directed against HIV infection

We are developing methods for somatic cell gene therapy directed against infection with human immunodeficiency virus by enhancing the antiviral resistance of target cells through the constitutive production of interferon-beta. Cells that have been transformed by plasmids or retroviral vectors carrying the human interferon-beta gene placed under the expression control of a murine H2Kb promoter fragment become resistant to HIV infection. Part of this enhanced resistance is due to inhibition of virus entry into the transformed cells, a hitherto unreported mechanism of interferon action.

Blocking of retroviral infection at a step prior to reverse transcription in cells transformed to constitutively express interferon beta

We are developing methods for somatic-cell gene therapy directed against infection with human immunodeficiency virus, by enhancing antiviral resistance of target cells through the constitutive production of autocrine interferon (IFN). Using the human IFN-beta coding sequence under the constitutive low-expression control of a 0.6-kb murine H-2Kb promoter-fragment, we have constructed a retroviral vector, HMB-KbHuIFN beta, and have transformed cells of the T98G human neuroblastoma line, the U-937 human promonocytic line, and the CEM human lymphocytic line. These human IFN-beta-transformed cell populations have acquired a low, constitutive production of human IFN, while replicating at a rate similar to that of untransformed cells and of cells transformed with the control vector carrying a human IFN-beta sequence encoding an inactive, mutated protein. In the three different cell populations tested, transformation with the HMB-KbHuIFN beta vector resulted in a 1.3-2.3 log10 reduction in the number of cells infected with a defective amphotropic MFG-LaZ retrovirus. A kinetic study of the fate of the MFG-LacZ retrovirus in the culture medium and intracellularly immediately after exposure of the cells to virus revealed a significant reduction of the appearance of intracellular virus in human IFN-beta-transformed cells. A similar effect was obtained by treating untransformed T98G, U-937, and CEM cells with exogenous human IFN-beta. The blocking effect of autocrine or exogenous human IFN-beta on viral entry was not limited to virus specific for the amphotropic receptor but was also obtained in murine IFN-beta-treated NIH 3T3 mouse fibroblasts infected with an ecotropic MFG-LacZ retrovirus. Infection of human IFN-beta-transformed CEM cells with human immunodeficiency virus type 1 gave comparable results. Immediately following exposure of the cells to human immunodeficiency virus, a kinetic study of the fate of the virus failed to reveal the appearance of intracellular virus and showed that the majority of the input virus remained in the extracellular medium. We conclude that low autocrine IFN-beta synthesis, or exposure of cells to exogenous IFN-beta, prevents virus from getting inside the cells, regardless of the virus receptor involved.

Development of methods for somatic cell gene therapy directed against viral diseases, using retroviral vectors carrying the murine or human interferon-beta coding sequence: establishment of the antiviral state in human cells

We are developing methods for somatic cell gene therapy directed against chronic and fatal virus infections, such as acquired immunodeficiency (AIDS), by transforming cells with a constitutively expressed interferon (IFN) coding sequence. Previous work from our laboratory has shown that stable antiviral expression (SAVE) can be obtained in murine BALB/c 3T3 cells and human U937 cells transformed with plasmids carrying either the murine or the human IFN-beta coding sequence placed under the expression control of a 0.6-kb Xho II-Nru I promoter region of the murine H-2Kb major histocompatibility complex (MHC) gene (Macé et al., 1991; Seif et al., 1991). In the present paper, we report the construction of murine (Mu) and human (Hu) IFN-beta-expressing retroviral vectors (pMPZen-MuIFN beta, pHMB-KbMuIFN beta) and the problems encountered. Because of the murine origin of commonly used packaging cells and the species specificity of IFN, it was evident that placing the murine IFN-beta sequence under constitutive expression control could result in the production of Mu IFN in the murine packaging system, and thereby lead to decreased vector production and also to enhanced resistance of target cells. Using a packaging cell line that releases a beta-galactosidase-expressing vector, we show that, as expected, Mu IFN-alpha/beta decreases vector production of murine packaging cells and also inhibits the transformation of target NIH-3T3 cells with this vector, but the presence of anti-Mu IFN antibodies rescues the viral titer of the packaging cells and restores the sensitivity of target cells to virus transformation. However, the same antibody treatment is unable to rescue the viral titer of psi-2 packaging cells producing autocrine Mu IFN-beta encoded by the pMPZen-MuIFN beta and pHMB-KbMuIFN beta vectors. Because of the species specificity of IFN, this problem is circumvented with the pMFG-HuIFN beta vector carrying the human IFN-beta sequence. In spite of the production of Hu IFN, murine psi-CRIP packaging cells are able to release retroviral vectors expressing Hu IFN-beta, and these amphotropic vectors can transform human MRC-5 cells and confer to these cells an enhanced resistance to vesicular stomatitis virus (VSV) infection.