Immune-regulatory properties carried by human amnion epithelial cells: Focus on the role of HLA-G and adenosinergic ectoenzymes

Human amnion epithelial cells (hAEC) can be efficiently isolated from full-term amnion membrane and have been gaining recognition as advanced medical products. Such cells originate directly from the embryo during the early phase of development and exert a crucial function in the establishment of a tolerogenic environment, to avoid maternal immune rejection. Amnion cell immuno-modulation may be exploited, but additional efforts are required to establish the mechanisms underlying such capacity. The way to fully clarify such an issue is so far long. Here we overview current knowledge on the effects on innate or adaptive immune cells offered by intact hAEC or secreted mediators, pinpointing the mechanisms to date elucidated by our group and others. We move from the description of hAEC general features to molecular intermediaries generating effects directly or indirectly on immune cells. We focus on the role of non-canonical HLA class I molecules, with emphasis on HLA-G, but expand such analysis on adenosinergic mediators, cytokines, and hAEC-derived microvesicles. Finally, we report the ongoing clinical trials exploiting hAEC multipotency and immune modulation.

Zoledronic acid boosts γδ T-cell activity in children receiving αβ+ T and CD19+ cell-depleted grafts from an HLA-haplo-identical donor

We demonstrated that γδ T cells of patients given HLA-haploidentical HSCT after removal of αβ⁺ T cells and CD19⁺ B cells are endowed with the capacity of killing leukemia cells after ex vivo treatment with zoledronic acid (ZOL). Thus, we tested the hypothesis that infusion of ZOL in patients receiving this type of graft may enhance γδ T-cell cytotoxic activity against leukemia cells. ZOL was infused every 28 d in 43 patients; most were treated at least twice. γδ T cells before and after ZOL treatments were studied in 33 of these 43 patients, till at least 7 mo after HSCT by high-resolution mass spectrometry, flow-cytometry, and degranulation assay. An induction of Vδ2-cell differentiation, paralleled by increased cytotoxicity of both Vδ1 and Vδ2 cells against primary leukemia blasts was associated with ZOL treatment. Cytotoxic activity was further increased in Vδ2 cells, but not in Vδ1 lymphocytes in those patients given more than one treatment. Proteomic analysis of γδ T cells purified from patients showed upregulation of proteins involved in activation processes and immune response, paralleled by downregulation of proteins involved in proliferation. Moreover, a proteomic signature was identified for each ZOL treatment. Patients given three or more ZOL infusions had a better probability of survival in comparison to those given one or two treatments (86% vs. 54%, respectively, p = 0.008). Our data indicate that ZOL infusion in pediatric recipients of αβ T- and B-cell-depleted HLA-haploidentical HSCT promotes γδ T-cell differentiation and cytotoxicity and may influence the outcome of patients.

Cytokines as anti-angiogenic agents in haematological malignancies

The role of angiogenesis in haematological malignancies has been recently recognized. In these tumors, angiogenesis has been investigated predominantly in the bone marrow (BM) compartment where it appears to be regulated by multiple interactions between malignant cells and different cell populations present in the tumor microenvironment. Thus, angiogenesis represents a therapeutic target that opens new perspectives for the treatment of haematological malignancies. Cytokines are small proteins that mediate intercellular communications, thus regulating important cellular functions, such as immune responses and angiogenesis. Some cytokines show anti-angiogenic properties through different mechanisms; these cytokines can interfere directly with biological functions of endothelial cells and/or target tumor cells inhibiting their capability to stimulate formation of new microvessels that are essential for tumor growth and dissemination. In this review we will summarize the current knowledge about the role of cytokines as anti-angiogenic agents in cancer, focusing our attention on the anti-angiogenic activity of IL-12 family members in haematological malignancies.

Absence of IL-12Rβ2 in CD33(+)CD38(+) pediatric acute myeloid leukemia cells favours progression in NOD/SCID/IL2RγC-deficient mice

Childhood acute myeloid leukemia (AML) is a hematological malignancy in which tumor burden is continuously replenished by leukemic-initiating cells (ICs), which proliferate slowly and are refractory to chemotherapeutic agents. We investigated whether interleukin (IL)-12, an immuno-modulatory cytokine with anti-tumor activity, may target AML blasts (CD45(+)CD33(+)) and populations known to contain leukemia ICs (that is, CD34(+)CD38(-), CD33(+)CD38(+) and CD44(+)CD38(-) cells). We demonstrate for the first time that: i) AML blasts and their CD34(+)CD38(-), CD33(+)CD38(+), CD44(+)CD38(-) subsets express the heterodimeric IL-12 receptor (IL-12R), ii) AML cells injected subcutaneously into NOD/SCID/Il2rg(-/-) (NSG) mice developed a localized tumor mass containing leukemic ICs and blasts that were virtually eliminated by IL-12 treatment, iii) AML cells injected intravenously into NSG mice engrafted within the first month in the spleen, but not in bone marrow or peripheral blood. At this time, IL-12 dramatically dampened AML CD45(+)CD33(+), CD34(+)CD38(-), CD33(+)CD38(+) and CD44(+)CD38(-) populations, only sparing residual CD33(+)CD38(+) cells that did not express IL-12Rβ2. From 30 to 60 days after the initial inoculum, these IL-12-unresponsive cells expanded and metastasized in both control and IL-12-treated NSG mice. Our data indicate that the absence of IL-12Rβ2 in pediatric AML cells favours leukemia progression in NOD/SCID/IL2Rγc-deficient mice.

Low-dose interferon-gamma-producing human neuroblastoma cells show reduced proliferation and delayed tumorigenicity

Interferon-γ (IFN-γ) directs T helper-1 cell differentiation and mediates antitumour effects in preclinical models. However, high-dose IFN-γ is toxic in vivo, and IFN-γ-transfected neuroblastoma (NB) cells secreting high amounts of the cytokine may be lost due to cell apoptosis or differentiation. Two human NB cell lines (ACN and SK-N-BE2(c)) differing as to genetic and phenotypic features were transfected with the human IFN-γ gene and selected on the grounds of the low concentrations of IFN-γ produced. In both IFN-γ-transfected cell lines, autocrine and paracrine activation of IFN-γ-mediated pathways occurred, leading to markedly reduced proliferation rate, to increased expression of surface HLA and CD40 molecules and of functional TNF binding sites. ACN/IFN-γ cells showed a significantly delayed tumorigenicity in nude mice as compared to parental cells. ACN/IFN-γ tumours were smaller, with extensive necrotic area as a result of a damaged and defective microvascular network. In addition, a significant reduction in the proliferation index was observed. This is the first demonstration that IFN-γ inhibits in vivo proliferation of NB cell by acting on the tumour cell itself. This effect adds to the immunoregulatory and antiangiogenic activities operated by IFN-γ in syngeneic tumour-bearing hosts.

Expression of costimulatory molecules in human neuroblastoma. Evidence that CD40+ neuroblastoma cells undergo apoptosis following interaction with CD40L

Tumour cells display low to absent expression of costimulatory molecules. Here, we have investigated the expression of costimulatory molecules (CD40, CD80, CD86, PD-1L, B7H2, OX40L and 4-1BBL) in human neuroblastoma (NB) cells, since virtually no information is available on this issue. Both established NB cell lines and primary tumours were tested by RT-PCR and flow cytometry. Neuroblastoma cell lines expressed the transcripts of all costimulatory molecule genes, but not the corresponding proteins. Culture of NB cell lines with human recombinant (r)IFN-gamma induced surface expression of CD40 in half of them. Primary NB cells showed CD40, CD80, CD86, OX40L, 4-1BBL, but not PD-1L and B7H2, mRNA expression. Surface CD40 was consistently detected on primary NB cells by flow cytometry. Interferon-gamma gene-transfected NB cells expressed constitutively surface CD40 and were induced into apoptosis by incubation with rCD40L through a caspase-8-dependent mechanism. CD40 may represent a novel therapeutic target in NB.

Cytokine gene expression in neoplastic B cells from human mantle cell, follicular, and marginal zone lymphomas and in their postulated normal counterparts

Cytokines may promote tumor growth by paracrine and/or autocrine pathways. Little information is available because malignant cells differ from their normal counterparts for the cytokine repertoire they express. Here we have investigated by reverse transcription-PCR the expression of 22 cytokine genes in neoplastic B lymphocytes from six patients with mantle cell lymphoma, 10 with follicular lymphoma, and 5 with marginal zone lymphoma and in their normal counterparts, i.e., naive, germinal center, and memory B cells, purified from tonsils. The overall profiles of cytokine gene expression in neoplastic B cells and in the corresponding normal B-cell subsets were similar, but some "holes" in the repertoire of malignant versus normal B lymphocytes were detected. Different "hole" combinations were identified consistently in mantle cell lymphoma, follicular lymphoma, and marginal zone lymphoma, thus representing molecular fingerprints of each individual lymphoma entity.

Expression and function of IL-12 and IL-18 receptors on human tonsillar B cells

IL-12 activates murine and human B cells, but little information is available as to the expression and function of IL-12R on human B lymphocytes. Here we show that the latter cells, freshly isolated from human tonsils, expressed the transcripts of both beta1 and beta2 chains of IL-12R and that beta2 chain mRNA was selectively increased (4- to 5-fold) by incubation with Staphylococcus aureus Cowan I bacteria or IL-12. B cell stimulation with IL-12 induced de novo expression of the transcripts of the two chains of IL-18R, i.e., IL-1 receptor-related protein and accessory protein-like. Functional studies showed that both IL-12 and IL-18 signaled to B cells through the NF-kappaB pathway. In the case of IL-12, no involvement of STAT transcription factors, and in particular of STAT-4, was detected. c-rel and p50 were identified as the members of NF-kappaB family involved in IL-12-mediated signal transduction to B cells. IL-12 and IL-18 synergized in the induction of IFN-gamma production by tonsillar B cells, but not in the stimulation of B cell differentiation, although either cytokine promoted IgM secretion in culture supernatants. Finally, naive but not germinal center or memory, tonsillar B cells were identified as the exclusive IL-12 targets in terms of induction of NF-kappaB activation and of IFN-gamma production.

Cytokine gene expression and T-cell proliferative responses in lymph node mononuclear cells from children with early stage human immunodeficiency virus infection

BACKGROUND AND OBJECTIVES

The immunologic events taking place in secondary lymphoid tissue from children with early stage human immunodeficiency virus (HIV) infection are poorly understood. The aim of this study was to investigate cytokine gene expression and proliferative responses in lymph node (LN) biopsies from five children with early stage HIV infection, in the context of LN morphology and viral load.

DESIGN AND METHODS

The design of the study was approved by the local Ethical Committee. Cytokine gene expression was studied in LN biopsies and in paired peripheral blood (PB) samples from HIV-infected children by reverse transcriptase-polymerase chain reaction. T-cell proliferation was assessed by 3H-thymidine incorporation. Viral burden in germinal centers was assessed by video densitometric analysis following immunohistochemical staining for HIV p24.

RESULTS

Interleukin (IL)-2, IL-4 and IL-5 mRNA were not detected in any LN or PB sample from HIV-infected children. Interferon (IFN)-gamma mRNA was found only in CD8+ cells. IL-12 p35, IL-10, transforming growth factor-(TGF)-beta1, regulated on activation normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and IL-16 transcripts were detected in all samples. Proliferation of LN and PB mononuclear cells to polyclonal mitogens and soluble (recall and HIV-related) antigens was impaired as compared with the responses in a group of age-matched healthy controls.

INTERPRETATION AND CONCLUSIONS

Changes in cytokine gene expression and T-cell proliferative responses are already detectable in lymph nodes from HIV-infected children at an early stage of disease.

Stromal cell-derived factor-1 as a chemoattractant for follicular center lymphoma B cells

BACKGROUND

Follicular center lymphoma displays widespread lymph node involvement at diagnosis. The chemoattractants that control the locomotion of follicular center lymphoma B cells have not been established. Stromal cell-derived factor-1 (SDF-1) is a CXC-class chemokine that enhances the migration of normal human B cells and is expressed in peripheral lymphoid tissues. Here we have investigated 1) whether SDF-1 stimulates the in vitro locomotion of follicular center lymphoma B cells and of their presumed normal counterparts (i. e., germinal center B cells) and 2) whether the same cells express SDF-1 transcripts.

METHODS

B cells were purified by immunomagnetic bead manipulation. Messenger RNA was detected by reverse transcription-polymerase chain reaction. Migration was assessed by the filter and collagen invasion assays. All P values were two sided.

RESULTS

Follicular center lymphoma B lymphocytes showed a statistically significant migratory response to 300 ng/mL SDF-1, both in the filter and in the collagen assays (P =.002 for each). Such response was mediated by the SDF-1 receptor, CXCR4. CD40 monoclonal antibody (MAb) and tonsillar germinal center B cells treated with CD40 MAb and recombinant interleukin 4, but not freshly isolated, migrated statistically significantly faster in the presence than in the absence of SDF-1 (P =.002 in both filter and collagen assays). Freshly isolated follicular center lymphoma and germinal center B cells expressed SDF-1 transcripts.

CONCLUSIONS

This study shows that SDF-1 substantially enhances the migration of follicular center lymphoma B cells but not the migration of freshly purified germinal center B cells. This difference may be related to the extended survival of follicular center lymphoma versus germinal center B cells. SDF-1 produced in follicular center lymphoma lymph nodes may play a role in the local dissemination of tumor cells.

Late Epstein-Barr virus infection of a hepatosplenic gamma delta T-cell lymphoma arising in a kidney transplant recipient

BACKGROUND AND OBJECTIVE

gd T-cell lymphomas are only exceptionally observed in transplanted patients. Aim of this study was the detailed characterization of one such case.

DESIGN AND METHODS

The patient developed spontaneous splenic rupture six years after kidney transplantation. The splenic red pulp was infiltrated by medium-sized and large lymphoid cells with two or more nucleoli. At autopsy, similar lymphoid cells infiltrated the hepatic sinusoids. Histologic, immunologic and molecular studies were carried out.

RESULTS

By immunohistochemistry, the atypical lymphoid cells were found to express CD3, CD45 and CD43, indicating their T-lineage origin. Approximately 99% of spleen mononuclear cells (MNC) were CD3(+), gammadelta TcR+, CD4-, CD8-, alphabeta TcR-. A clonal gammadelta TcR rearrangement (Vgamma1-Jgamma1.3/2.3-Cgamma2; Vdelta1-Ddelta2-Jdelta1) was detected. The final diagnosis was peripheral T-cell lymphoma, hepato-splenic gammadelta-type. EBV infection of spleen MNC was documented by molecular studies. However, in situ hybridization for EBER-1 (EBV-RNA) showed that only a minority of malignant lymphoid cells (5-7%) were EBV-infected.

INTERPRETATION AND CONCLUSIONS

It is concluded that EBV infection was as a late event involving an already transformed gd T-cell clone.

Ultrastructural and functional studies of the interaction between IL-12 and IL-2 for the generation of lymphokine-activated killer cells

IL-12 promotes generation of LAK activity in short-term-cultured NK cells, but information on the structure and function of IL-12-induced LAK cells is not yet available. The latter issues have been here investigated with emphasis on interactions between IL-12 and IL-2. Peripheral blood mononuclear cells (MNC) exposed to IL-12 for 5-7 days displayed a decrease in the amount and density of the matrix of large granular lymphocyte (LGL)-associated granules. In cells cultured with IL-12 and IL-2 for 5-7 days, empty vacuoles were predominant and the electron-dense matrix was scanty. In MNC incubated with IL-2 for 5-7 days, most granules were loaded with electron-dense matrix. IL-12 and IL-2 displayed an additive effect on LAK cell cytotoxicity until approximately 48 h in culture which was followed by a sharp decline. Immunocytochemical and biochemical studies demonstrated that MNC cultured for 5-7 days with IL-12 and IL-2 displayed downregulated perforin expression and upregulated granzyme B expression. Fas ligand expression was virtually undetectable in MNC cultured for 5-7 days with or without cytokines. It appears that perforin downregulation plays a major role in the reduced cytotoxicity of MNC cultured with IL-12 and IL-2 for 5-7 days.

rC5a directs the in vitro migration of human memory and naive tonsillar B lymphocytes: implications for B cell trafficking in secondary lymphoid tissues

Human C5a is a potent chemoattractant for granulocytes, monocytes, and dendritic cells. In mice C5a has been shown to be chemotactic for germinal center (GC) B cells. To date, no information is available on the effects of C5a on human B cell locomotion. Here we demonstrate that rC5a increases polarization and migration of human tonsillar B cells. The locomotory response was due to both chemokinetic and chemotactic activities of rC5a. Moreover, memory and, at a lesser extent, naive B cell fractions from purified tonsillar populations displayed rC5a-enhanced migratory properties, whereas GC cells did not. Flow cytometry revealed C5aR (CD88) on approximately 40% memory and 10% naive cells, respectively, whereas GC cells were negative. Immunohistochemistry showed that a few CD88+ cells were of the B cell lineage and localized in tonsillar subepithelial areas, where the majority of memory B cells settle. Pretreatment of memory B cells with the CD88 mAb abolished their migratory responsiveness to rC5a. Finally, the C5 gene was found to be expressed in naive, GC, and memory B lymphocytes at both the mRNA and the protein level. This study delineates a novel role for C5a as a regulator of the trafficking of human memory and naive B lymphocytes and supports the hypothesis that the B cells themselves may serve as source of C5 in secondary lymphoid tissues.

Recombinant tumor necrosis factor enhances the locomotion of memory and naive B lymphocytes from human tonsils through the selective engagement of the type II receptor

Recent studies performed in mice knocked out for the tumor necrosis factor (TNF ), the lymphotoxin-alpha, or the type I TNF receptor (R), genes have shown that these animals display gross defects in germinal center (GC) formation, suggesting that members of the TNF and TNFR superfamilies are involved in the control of B-cell migration. Based on these premises, we have here investigated the effects of human recombinant (r) TNF on the polarization and locomotion of tonsillar B cells. rTNF increased the spontaneous polarization and locomotion of unfractionated tonsillar B lymphocytes in a dose-dependent manner by inducing a true chemotactic response. Memory (IgD-, CD38(-)) and naive (IgD+, CD38(-)), but not GC (IgD-, CD38(+)) B cells purified from total tonsillar B lymphocytes, showed a significantly higher locomotion in the presence than in the absence of rTNF. Accordingly, type I and II TNF receptors (TNFRs) were detected by flow cytometry on the surface of memory and naive, but not GC, B lymphocytes. Blocking experiments with monoclonal antibodies to type I or II TNFR showed that rTNF enhanced the spontaneous chemotaxis of memory and naive B cells through the selective engagement of type II TNFR. Finally, the TNF gene was found to be expressed in memory, naive and GC B lymphocytes; the cytokine was released in culture supernatants from the three B-cell subsets after stimulation. These data may support the hypothesis that human TNF is involved in the paracrine and perhaps autocrine control of B-cell migration in secondary lymphoid tissues.

The patterns of IL2, IFN-gamma, IL4 and IL5 gene expression in Hodgkin's disease and reactive lymph nodes are similar

BACKGROUND AND OBJECTIVE

The lymph nodes involved in classic Hodgkin's disease (HD), i.e. mixed cellularity (MC) and nodular sclerosis (NS) subtypes, usually contain few (1-2%) Reed-Sternberg (RS) cells scattered in a background of lymphocytes, eosinophils, plasma cells and neutrophils. CD4+ T-lymphocytes are increased in number, express activation markers and cluster around RS cells. The presence of eosinophilia in most HD patients and the presence of hyper-IgE in a subset of them may suggest that activated lymph node T cells release large amounts of IL5 and IL4, respectively.

METHODS

The expression of four T-cell-associated cytokine genes, i.e. interleukin (IL)2, IL4, IL5 and interferon (IFN)-gamma, in frozen sections of 14 HD (7 MC, 7 NS) and 10 reactive lymph nodes was investigated by qualitative and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). T-cell clones were also raised from purified CD4+ lymphocytes of one HD lymph node and one reactive lymph node and tested for IL2, IL4, IL5 and IFN-gamma secretion in culture supernatants by immunoassays.

RESULTS

The transcripts of all the cytokine genes were detected in every lymph node irrespective of the HD or reactive nature. HD or reactive lymph node-derived CD4+ T-cell clones released the four cytokines according to a predominant T-helper (Th)0-type pattern. In more than half of the lymph nodes of either HD or reactive nature, there was a predominance of IL4 over IFN-gamma mRNA production (Th2-type pattern). In the remaining HD or reactive lymphadenopathies, either a balanced IL4/IFN-gamma mRNA ratio (Th0-type pattern) or a predominance of IFN-gamma over IL4 mRNA expression (Th1-type pattern) was observed.

INTERPRETATION AND CONCLUSIONS

The overall pattern of cytokine gene expression in classic HD is similar to that detected in reactive lymph nodes. Further studies are needed to determine whether differences in the absolute concentrations of cytokines released in HD versus reactive lymph nodes and the long-standing course of HD versus the self-limiting nature of reactive adenopathies may explain certain peculiar features of HD, such as eosinophilia, for example.

Transcriptional repression by the human homeobox protein EVX1 in transfected mammalian cells

The human homeobox protein EVX1 (EVX1) is thought to play an important role during embryogenesis. In this study, the effect of EVX1 on gene transcription has been investigated in transfected mammalian cells. EVX1 expression represses transcription of a reporter gene directed by either cell-specific or viral promoter/enhancer sequences in a variety of mammalian cell lines and in a concentration-dependent manner. Transcriptional repression is independent of the presence of DNA-binding sites for EVX1 in all the promoters we tested. Furthermore, repression by EVX1 is evident also using a TATA-less minimal promoter in the reporter construct. A carboxyl-terminal proline/alanine-rich region of EVX1 seems to be responsible for the transcriptional repression activity, as suggested by transfection of EVX1 mutants. We speculate that the repressor function of EVX1 contributes to its proposed role in embryogenesis.

Expression of HOXC4 homeoprotein in the nucleus of activated human lymphocytes

We have analyzed the expression of homeoproteins of the HOX family in resting and activated lymphoid cells and in neoplastic lymphoid cell lines by the use of monoclonal antibodies (MoAbs) already shown to react with the homeoproteins HOXA10, HOXC6, and HOXD4, respectively. Anti-HOXA10 and C6 MoAbs DIDi not show any reactivity with the lymphoid cells tested, whereas anti-HOXD4 MoAb stained few resting peripheral blood lymphocytes (PBLs) and most phytohemagglutinin (PHA)-stimulated PBLs as early as 6 hours after stimulation. The pattern of staining of PHA-activated PBLs is reminiscent of the stages of nucleolar fragmentation in different phases of the cell cycle. The MoAb reacted also with activated or Epstein-Barr virus-transformed B cells, with clonal or polyclonal T and natural killer (NK) cells, with leukemic T-cell lines, and with a Burkitt's lymphoma cell line. RNAse protection experiments, per formed with probes specific for HOXD4 or for the highly homologous HOXA4, HOXB4, and HOXC4, belonging to the same paralogy group, indicated that only HOXC4 mRNA is present in resting or activated PBLs. Northern blot analysis on polyA+ RNA from activated PBLs or Raji cells showed the presence of two different HOXC4 transcripts of 2.8 and 1.9 kb. Gel retardation and Southwestern blot assays showed the presence of a 32-kD homeoprotein with DNA-binding properties typical of a HOX4 homeoprotein in nucleolar extracts of PHA-activated, but not of resting, lymphocytes. Taken together, these data indicate that the HOXC4 homeoprotein is expressed in activated and/or proliferating lymphocytes of the T-, B-, or NK-cell lineage, whereas it is weakly expressed in a minority of resting cells. The early expression and the nucleolar localization suggest an involvement of HOXC4 in the regulation of genes controlling lymphocyte activation and/or proliferation.

Differential DNA binding properties of three human homeodomain proteins

The products of three human homeobox containing (HOX) genes, 2C, 3C and 4B, were produced in insect cells using the Baculovirus expression system and purified to near homogeneity. In this system we observed that the DNA binding forms of the three proteins are not glycosylated. HOX 3C and 4B are phosphorylated in insect cells, while HOX 2C is not. The three HOX proteins bind to a DNA sequence known to be a target site for Antennapedia protein with a very similar affinity (Kd = 1-2 x 10(-9) M). We then measured their binding properties to four human sequences present in the HOX 3D, 4C, 1C and 4B promoters. Two of these sequences have been reported to be binding sites for HOX proteins. HOX 2C, 3C and 4B behaved quite differently, showing low affinity for promoters of genes located upstream from their own gene in the HOX clusters and a higher affinity for regulatory sequences of their own gene and downstream HOX genes.