Benedetta Costantini

Functional characterization of CD4+ T cells in aplastic anemia

The role of CD4(+) T cells in the pathogenesis of aplastic anemia (AA) is not well characterized. We investigate CD4(+) T-cell subsets in AA. Sixty-three patients with acquired AA were studied. Th1 and Th2 cells were significantly higher in AA patients than in healthy donors (HDs; P = .03 and P = .006). Tregs were significantly lower in patients with severe AA than in HDs (P < .001) and patients with non-severe AA (P = .01). Th17 cells were increased in severe AA (P = .02) but normal in non-severe AA. Activated and resting Tregs were reduced in AA (P = .004; P = .01), whereas cytokine-secreting non-Tregs were increased (P = .003). Tregs from AA patients were unable to suppress normal effector T cells. In contrast, AA effector T cells were suppressible by Tregs from HDs. Th1 clonality in AA, investigated by high-throughput sequencing, was greater than in HDs (P = .03). Our results confirm that Th1 and Th2 cells are expanded and Tregs are functionally abnormal in AA. The clonally restricted expansion of Th1 cells is most likely to be antigen-driven, and induces an inflammatory environment, that exacerbate the functional impairment of Tregs, which are reduced in number.

Human Mesenchymal Stem Cells from Chorionic Villi and Amniotic Fluid are not Susceptible to Transformation after Extensive in Vitro Expansion

Mesenchymal stem cells (MSCs) are promising candidates for cell therapy and tissue engineering. Increasing evidence suggests that MSCs isolated from fetal tissues are more plastic and grow faster than adult MSCs. In this study, we characterized human mesenchymal progenitor cells from chorionic villi (CV) and amniotic fluid (AF) isolated during the first and second trimesters, respectively, and compared them with adult bone marrow-derived MSCs (BM). We evaluated 10 CV, 10 AF, and 6 BM samples expanded until the MSCs reached senescence. We used discarded cells from prenatal analyses for all the experiments. To evaluate the replicative stability of these cells, we studied the telomerase activity, hTERT gene transcription, and telomere length in these cells. Spontaneous chromosomal alterations were excluded by cytogenetic analysis. We studied the expression of c-myc and p53, tumor-associated genes, at different passage in culture and the capacity of these cells to grow in an anchorage-independent manner by using soft agar assay. We isolated homogeneous populations of spindle-shaped CV, AF, and BM cells expressing mesenchymal immunophenotypic markers throughout the period of expansion. CV cells achieved 14 ± 0.9 logs of expansion in 118 days and AF cells achieved 21 ± 0.9 logs in 118 days, while BM cells achieved 11 × 0.4 logs in 84 days. Despite their high proliferation capacity, fetal MSCs showed no telomerase activity, no hTERT and c-myc transcriptions, and maintained long, stable telomeres. A constant expression level of p53 and a normal karyotype were preserved throughout long-term expansion, suggesting the safety of fetal MSCs. In conclusion, our results indicate that fetal MSCs could be an alternative, more accessible resource for cell therapy and regenerative medicine.

The effects of 5-azacytidine on the function and number of regulatory T-cells and T-effectors in myelodysplastic syndrome

Expansion of regulatory T cells occurs in high-risk myelodysplastic syndrome and correlates with a poor prognosis. DNA methyltransferase inhibitors, particularly 5-azacytidine, have been shown to increase the survival of patients with high-risk myelodysplastic syndrome. It is not entirely clear whether this improvement in patients’ survival is related to the effects of DNA methyltransferase inhibitors on the immune system and/or the direct effect of these drugs on the dysplastic clone. In this study we investigated the effect of 5-azacytidine on the function and proliferation capability of regulatory T cells and T-helper cells. The number and function of CD4+ T-cell subsets in 68 patients with intermediate-2/high-risk myelodysplastic syndrome were serially assessed at diagnosis and following treatment. The in-vitro effects of 5-azacytidine on CD4+ T-cell subsets isolated from both healthy donors and patients with myelodysplastic syndrome were also investigated. The number of peripheral blood regulatory T cells was significantly higher in myelodysplastic syndrome patients than in healthy donors and responders to treatment (P=0.01). The absolute numbers of T-helper 1 and T-helper 2, but not T-helper 17, cells were significantly reduced following 12 months of treatment (P=0.03, P=0.03). The in vitro addition of 5-azacytidine to CD4+ T cells reduced the proliferative capacity of regulatory T cells (P=0.03). In addition, the 5-azacytidine-treated regulatory T cells had reduced suppressive function and produced larger amounts of interleukin-17. The FOXP3 expression in 5-azacyti-dine-treated T-effectors was also increased. Interestingly, these FOXP3+/interleukin-17+ cells originated mainly from effector T cells rather than regulatory T cells. Our data suggest that 5-azacytidine has profound effects on CD4+ T cells, which correlate with disease status after treatment. Furthermore, despite the demethylation of the FOXP3 promoter and increased FOXP3 expression following 5-azacytidine treatment, these phenotypic regulatory T cell-like cells lack the regulatory function and cytokine profile of regulatory T cells. These findings are important in correlating the clinically relevant immunomodulatory effects of 5-azacytidine.

Deep phenotyping of Tregs identifies an immune signature for idiopathic aplastic anemia and predicts response to treatment

Idiopathic aplastic anemia (AA) is an immune-mediated and serious form of bone marrow failure. Akin to other autoimmune diseases, we have previously shown that in AA regulatory T cells (Tregs) are reduced in number and function. The aim of this study was to further characterize Treg subpopulations in AA and investigate the potential correlation between specific Treg subsets and response to immunosuppressive therapy (IST) as well as their in vitro expandability for potential clinical use. Using mass cytometry and an unbiased multidimensional analytical approach, we identified 2 specific human Treg subpopulations (Treg A and Treg B) with distinct phenotypes, gene expression, expandability, and function. Treg B predominates in IST responder patients, has a memory/activated phenotype (with higher expression of CD95, CCR4, and CD45RO within FOXP3(hi), CD127(lo) Tregs), expresses the interleukin-2 (IL-2)/STAT5 pathway and cell-cycle commitment genes. Furthermore, in vitro-expanded Tregs become functional and take on the characteristics of Treg B. Collectively, this study identifies human Treg subpopulations that can be used as predictive biomarkers for response to IST in AA and potentially other autoimmune diseases. We also show that Tregs from AA patients are IL-2-sensitive and expandable in vitro, suggesting novel therapeutic approaches such as low-dose IL-2 therapy and/or expanded autologous Tregs and meriting further exploration.

Gene expression profile of cytokines in patients with chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation with reduced conditioning.

There are no reliable markers useful to predict the onset or the evolution of chronic graft-versus-host disease (cGVHD) after allogeneic hematopoietic stem cell transplantation (HSCT), although several candidate biomarkers have been identified from limited hypothesis-driven studies. In this study we evaluated 14 patients who received a reduced intensity conditioning HSCT. Seven patients had cGVHD, whereas 7 never developed cGVHD during the period of observation. The expression of 114 cytokines in immunoselected cell populations was explored by microarray analysis and 11 cytokines were selected for further evaluation by real-time PCR. Differential gene expression measurements showed a significant up-regulation for INFγ (interferon, gamma) in CD8+ and for TNFSF3 (tumor necrosis factor superfamily, member 3) and for TNFSF10 (tumor necrosis factor superfamily, member 10) in CD14+ cell population when comparing cGVHD with control samples. The expression levels were significantly decreased for TNFSF10 in CD8+ cell population and for TNFSF12 (tumor necrosis factor superfamily, member 12) and for PDGFβ (platelet-derived growth factor, beta) in CD4+. Our data seem to suggest that different immune populations can play a role in cGVHD pathogenesis and the early detection of gene expression profile in these patients could be useful in the monitoring of GVHD. We hypothesized that PDGFβ down-regulation could represent a negative feedback to compensate for enhanced expression of its receptor recently reported.

Telomere length, c-myc and mad-1 expression could represent prognosis markers of myelodysplastic syndrome

Telomere dysfunction might generate genomic instability leading to the progression of myelodysplastic syndromes (MDS) into acute myeloid leukemia (AML). We investigated telomere length (TL), telomerase activity (TA) and hTERT, c-myc, mad1, and p53 expression in the bone marrow of patients with MDS (n=109), AML (n=47) and in controls (n=24). TL was lower in MDS patients than in controls (p<0.001) and higher in L-MDS (low, intermediate-1 IPSS, p<0.01) respect H-MDS (high, intermediate-2 IPSS, p<0.01) patients. Mad-1 expression was higher in MDS patients than in controls (p<0.01), c-myc expression was highest in AML and in H-MDS patients. Our results show that the telomere dynamics might be useful for stratifying patients according to a risk scoring system.

Prognostic role of immunohistochemical analysis of 5 mc in myelodysplastic syndromes.

Aberrant DNA methylation at CpG islands within promoters is increasingly recognised as a common event in human cancers and has been associated with the silencing of important tumour suppressor genes. Epigenetic therapy using hypomethylating agents has demonstrated clinical effectiveness; the drugs azacitidine and decitabine have been approved for the treatment of MDS.

Low-dose Gemtuzumab-Ozogamicin as post-consolidation therapy in elderly patients with acute myeloid leukaemia: a pilot study

T., Heldmann, K., Carmi, R., Parvari, R., Beit-Or, H., Goldman, B., Peleg, L., Levy-Lahad, E., Renbaum, P., Legum, S., Shomrat, R., Yeger, H., Benbenisti, D., Navon, R., Dror, V., Shohat, M., Magal, N., Navot, N. & Eyal, N. (1998) Prevalence of glucocerebrosidase mutations in the Israeli Askenazi Jewish poulation. Human Mutations, 12, 240–244. Pocovi, M., Cenarro, A., Civeira, F., Torralba, M.A., Perez-Calvo, J.I., Mozas, P., Giraldo, P., Girait, M., Myers, R.H., Cupples, L.A. & Ordovas, J.M. (1998) Beta –glucocerebrosidase gene locus as a link for Gaucher’s disease and familial hypo-alfa-lipoproteinaemia. Lancet, 351, 1919–1923.

Overexpression of CDKN2B (p15INK4B) and altered global DNA methylation status in mesenchymal stem cells of high-risk myelodysplastic syndromes

Overexpression of CDKN2B (p15INK4B) and altered global DNA methylation status in mesenchymal stem cells of high-risk myelodysplastic syndromes

Immunomodulatory Effects of Tyrosine Kinase Inhibitors (TKIs) in Vitro and in Vivo Study.

Pathogenesis of chronic graft-versus-host disease (cGVHD) is incompletely defined, involving donor-derived CD4 and CD8-positive T lymphocytes as well as B cells. Standard treatment is lacking for steroid-dependent/refractory cases; therefore, the potential usefulness of tyrosine kinase inhibitors (TKIs) has been suggested, based on their potent antifibrotic effect. However, TKIs seem to have pleiotropic activity. We sought to evaluate the in vitro and in vivo impact of different TKIs on lymphocyte phenotype and function. Peripheral blood mononuclear cells (PBMCs) from healthy donors were cultured in the presence of increasing concentrations of nilotinib, imatinib, dasatinib, and ponatinib; in parallel, 44 PBMC samples from 15 patients with steroid-dependent/refractory cGVHD treated with nilotinib in the setting of a phase I/II trial were analyzed at baseline, after 90, and after 180 days of therapy. Flow cytometry was performed after labeling lymphocytes with a panel of monoclonal antibodies (CD3, CD4, CD16, CD56, CD25, CD19, CD45RA, FoxP3, CD127, and 7-amino actinomycin D). Cytokine production was assessed in supernatants of purified CD3+ T cells and in plasma samples from nilotinib-treated patients. Main T lymphocyte subpopulations were not significantly affected by therapeutic concentrations of TKIs in vitro, whereas proinflammatory cytokine (in particular, IL-2, IFN-γ, tumor necrosis factor-α, and IL-10) and IL-17 production showed a sharp decline. Frequency of T regulatory, B, and natural killer (NK) cells decreased progressively in presence of therapeutic concentrations of all TKIs tested in vitro, except for nilotinib, which showed little effect on these subsets. Of note, naive T regulatory cell (Treg) subset accumulated after exposure to TKIs. Results obtained in vivo on nilotinib-treated patients were largely comparable, both on lymphocyte subset kinetics and on cytokine production by CD3-positive cells. This study underlines the anti-inflammatory and immunomodulatory effects of TKIs and supports their potential usefulness as treatment for patients with steroid-dependent/refractory cGVHD. In addition, both in vitro and in vivo data point out that compared with other TKIs, nilotinib could better preserve the integrity of some important regulatory subsets, such as Treg and NK cells.