Th17 and Foxp3(+) T regulatory cell dynamics and distribution in myelodysplastic syndromes.

Foxp3(+) T regulatory cells (Tregs) and Th17 cells accumulate synchronously at tumor sites during cancer progression, where their interplay is apparently affecting the efficiency of the antitumor response. In myelodysplastic syndromes, a hematopoietic malignancy of myeloid origin, Tregs are highly increased in the late stages of the disease (L-MDS), but the mechanisms driving Treg expansion and the interaction between Treg and Th17 cell dynamics are still unknown. We demonstrate that the proliferative capacity of Tregs is deficient during the early MDS stages (E-MDS), while in L-MDS it returns to normal levels. In addition, synchronously to Treg expansion, L-MDS patients exhibit increased numbers of functionally competent bone marrow IL-17(+) and FOXP3(+)/IL-17(+) cells, in contrast to E-MDS patients, where Th17 cells are significantly decreased and hypofunctional. Our findings suggest similar kinetics of Treg and Th17 cells between MDS and solid tumors, indicating a common immune pathogenetic pathway between diverse cancer types.

Global impairment of CD4+CD25+FOXP3+ regulatory T cells in idiopathic pulmonary fibrosis.

RATIONALE: The implication of T cells in the pathogenesis of idiopathic pulmonary fibrosis (IPF) is controversial. CD4(+)CD25(+)FOXP3(+) regulatory T cells (Tregs) are pivotal in maintaining immune homeostasis, but their role in IPF pathophysiology has not yet been studied. OBJECTIVES: To explore Treg dynamics and function in IPF. METHODS: Treg levels and dynamics were analyzed by flow cytometry in the peripheral blood (PB) and bronchoalveolar lavage (BAL) of 21 patients with IPF, 35 patients with lung diseases other than IPF (patients without IPF), 20 patients with collagen vascular diseases with pulmonary parenchymal involvement (CVD-IP), and 28 healthy volunteers. The suppression of autologous CD4(+)CD25(-) cell-proliferative responses and cytokine release by magnetic bead-isolated Tregs was evaluated by proliferation assays and cytometric bead array. Correlations of Treg function and levels with lung function parameters were also performed. MEASUREMENTS AND MAIN RESULTS: In patients with IPF, both BAL and PB Tregs were reduced compared with those of healthy volunteers and patients without IPF, although not always significantly. Treg levels were not affected by the administration of low-dose prednisone in four nonresponding patients. The suppressor potential of BAL and PB Tregs was compromised in patients with IPF and patients with CVD-IP, compared with healthy volunteers and patients without IPF. Similarly, the Treg-induced suppression of helper T-cell type 1 and 2 cytokine secretion was impaired in the BAL of patients with IPF and patients with CVD-IP. Moreover, the defective function of BAL Tregs correlated highly with parameters of disease severity. CONCLUSIONS: This study provides the first evidence of global Treg impairment in IPF that strongly correlates with disease severity, suggesting a role for Tregs in the fibrotic process.

Hydroxyurea (HU) is effective in reducing JAK2V617F mutated clone size in the peripheral blood of essential thrombocythemia (ET) and polycythemia vera (PV) patients.

Ph-negative chronic myeloproliferative disorders (Ph(neg)cMPD) are treated according to the estimated vascular risk. The recent discovery of V617F point mutation of the JAK2 kinase, which frequently occurs in these diseases, has not changed their management so far. However, emerging data tend to support a prothrombotic role for the mutation, along with a better response of JAK2V617F mutated patients to hydroxyurea treatment. Our data further support this notion.

In vitro effects of the farnesyltransferase inhibitor tipifarnib on myelodysplastic syndrome progenitors.

BACKGROUND: Farnesyltransferase inhibitors (FTIs) target proteins needing prenylation for functioning. Tipifarnib (Zarnestra), a potent and specific inhibitor of farnesyltransferase, showed considerable activity in phase I and II studies in myelodysplastic syndrome (MDS), but the optimal regimen achieving high response rates with minor myelosuppression remains to be determined. Additionally, a direct effect on purified human MDS progenitors has not yet been shown. METHODS: MDS and normal CD34+ cells isolated by using immunomagnetic beads were plated for short-term cultures in semisolid media or liquid cultures for flow-cytometric assessment of apoptosis in the presence of either DMSO or various FTI concentrations. RESULTS: Tipifarnib exerted selective in vitro toxicity against clonal MDS hematopoiesis at concentrations less than 10 nM the effect being more prominent in white cell progenitors. This action was not due to apoptosis induction as both normal and MDS progenitors displayed equivalent DiOC3 and annexin V expression up to 72 h after exposure to tipifarnib. CONCLUSION: The leukemic clone is more susceptible in tipifarnib than normal progenitors. Since myelosuppression represents the main obstacle in the clinical use of tipifarnib in MDS, further reduction of the currently employed dose will potentially result in a more tolerable regimen without compromising its antileukemic action.

The JAK2V617F Point Mutation Increases the Osteoclast Forming Ability of Monocytes in Patients with Chronic Myeloproliferative Neoplasms and Makes their Osteoclasts more Susceptible to JAK2 Inhibition.

JAK2V617F is a gain of function point mutation that occurs in Myeloproliferative Neoplasm (MPN) patients and deranges their hemopoiesis at cellular level. We speculate that hyperfunctioning JAK2 can modify osteoclast (OCL) homeostasis in MPN patients. We studied 18 newly diagnosed MPN patients and four age-matched normal donors (ND). Osteoclast forming assays started from selected monocytes also and under titrated concentrations of the JAK2 Inhibitor AG-490 (Tyrphostin). Genomic DNA was extracted from the formed osteoclasts, and the JAK2V617F/JAK2WT genomic DNA ratio was calculated. OCLs formed from monocytes derived from heterozygous (Het) for the JAK2V617F mutation MPN patients, were three times more compared to those from JAK2 wild type (WT) MPN patients (p=0,05) and from ND as well (p=0,03). The ratio of JAK2V617F/JAK2WT genomic DNA was increased in OCLs compared to the input monocyte cells showing a survival advantage of the mutated clone. In comparison to ND and JAK2 WT MPN patients, OCLs from patients JAK2V617F (Het) were more susceptible to JAK2 inhibition. These alterations in osteoclast homeostasis, attributed to mutated JAK2, can deregulate the hemopoietic stem cell niche in MPN patients.

CD1d expression as a prognostic marker for chronic lymphocytic leukemia.

We analyzed the expression of CD1d, an antigen-presenting molecule, on peripheral blood leukemic cells of cases of chronic lymphocytic leukemia (CLL) by flow cytometry. We demonstrated variable expression of CD1d on leukemic lymphocytes and an association between high expression of CD1d with shorter time to treatment and overall survival of patients. CD1d was positively associated with CD38 expression, but not with unmutated heavy chain variable (VH) mutational status or adverse cytogenetics of leukemic lymphocytes. Our findings support that CD1d expression is a prognostic marker for CLL.

Has introduction of azacytidine in everyday clinical practice improved survival in late-stage Myelodysplastic syndrome? A single center experience.

Data derived from clinical trials consistently show a prolongation of overall survival of late-stage MDS patients with the introduction of azacytidine. Nevertheless, the applicability of the above results to real-world clinical settings may be questionable due to the strict design, the controlled medical environment, and the limited patient sample of explanatory studies. We retrospectively compared the outcome of two well-balanced groups of late-stage MDS patients. The first consisted of 46 patients treated with azacytidine (AZA cohort) and the second of 41 patients treated with other agents (non-AZA cohort). Patients in the AZA cohort displayed superior survival compared to the non-AZA ones. However, subgroup analysis revealed that azacytidine conferred a significant survival advantage only in patients with AML-MDS and those who attained a CR at any time after treatment initiation, while all other patients displayed comparable outcome with the non-AZA cohort. Larger series are needed to determine which patients benefit most from azacytidine therapy.

Safety and efficacy of 5-azacytidine treatment in myelodysplastic syndrome patients with moderate and mild renal impairment.

Myelodysplastic syndrome (MDS) patients with renal impairment (RI) were not assessed in the approval trials of 5-azacytidine, thus the optimal use of 5-azacytidine in such patients is currently undefined. We retrospectively analyzed 42 IPSS intermediate-2 and high-risk patients with moderate, mild or no RI undergoing 5-azacytidine therapy in a non-trial setting. We demonstrate that patients in all three groups achieved comparable responses and had similar overall and event-free survival. Likewise, both treatment toxicity and dose adjustments were not significantly influenced by renal function status. A transient but reversible decline in glomerular filtration rate was observed in patients either with or without RI, without affecting the therapeutic schedule. Our results provide the first evidence that 5-azacytidine is effective and well-tolerated in patients with mild and moderate RI and, if confirmed by prospective randomized studies, advocate that such patients can be managed in an analogous fashion to patients with normal renal function.

The diagnostic value of CD1d expression in a large cohort of patients with B-cell chronic lymphoproliferative disorders.

Immunophenotyping is indispensable in the differential diagnosis of B-cell chronic lymphoproliferative disorders (B-CLPDs). However, B-CLPDs often show overlapping immunophenotypic profiles and may be diagnostically challenging. CD1d is an HLA class I-like molecule that presents glycolipids to invariant natural killer T cells. Normal mature B cells constitutively express CD1d, but with the exception of some conflicting data, its expression in B-CLPDs is unknown. We demonstrate that in 222 B-CLPD cases, CD1d expression of less than 45% is strongly predictive of CLL (likelihood ratio, 32.3; specificity, 97.4%; sensitivity, 84.1%). In addition, CD1d showed significantly higher staining intensity in splenic marginal zone lymphoma compared with atypical hairy cell leukemia, lymphoplasmacytic lymphoma, and mantle cell lymphoma, thus allowing the discrimination of the former from the latter immunophenotypically overlapping B-CLPDs. It is important to note that in a given patient, CD1d expression on malignant B cells was similar between tissues and remained unaffected by disease stage and treatment status. Our findings strongly argue for the incorporation of CD1d into routine lymphoma panels.

Dynamics of telomere's length and telomerase activity in Philadelphia chromosome negative myeloproliferative neoplasms.

Telomere exhaustion and increased telomerase activity are associated with the acquisition of aggressive molecular events in a variety of haematological malignancies. In Philadelphia chromosome negative myeloproliferative neoplasms (Ph(neg)MPN's), telomere dynamics during clonal evolution of these diseases have not yet been fully elucidated. Herein we demonstrated that telomere shortening is a global phenomenon in Ph(neg)MPN's, irrespective of disease phenotype, treatment administration and JAK2V617F mutational status but the presence of additional cytogenetic abnormalities further affects them. Consistent with the above finding, TA was upregulated in CD34+ haemopoietic progenitors from almost all Ph(neg)MPN subgroups compared to healthy donors. Moreover, TL below the cut-off value of 27% could predict disease progression in Ph(neg)MPN patients (PFS at 5 years 39% vs 81%). Thus, TL emerges as a new prognostic marker in Ph(neg)MPN, reflecting probably the genetic instability of highly proliferating MPN clones.

Hemopoiesis in Ph-negative chronic myeloproliferative disorders.

Chronic myeloproliferative disorders (cMPDs) are clonal hemopoietic malignancies arising at the multipotent stem cell level. These conditions are characterized by increased blood count, marrow hyperplasia and extramedulary hemopoiesis. Vascular events might complicate their course, and transformation to either acute leukemia or myelofibrosis can finally occur. Among cMPDs, Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF) belong to the group of Ph-negative cMPDs. Although they share common pathogenetic features, these entities have a quite different prognosis. The common pathogenetic basis of Ph-negative cMPDs was recognized long ago, and it was suggested that a stimulating factor might enhance bone marrow hemopoietic activity. Hemopoietic progenitors from cMPDs show hypersensitivity to low levels of a variety of hemopoietic cytokines. The independency of erythroid precursors from erythropoietin became the first surrogate marker of an abnormal hemopoietic clone. This clone is characterized by increased proliferation and survival, as well as by decreased apoptosis, leading to the accumulation of mature blood cells that additionally show a phenotype of activated cells. Recently four independent groups have described an activating point mutation in the JAK2 kinase as a key pathogenetic event in Ph-negative cMPDs. JAK2 is a tyrosine kinase that acts as a second intracellular messenger for many hemopoietic cytokine receptors. It is now believed that jacking up hemopoiesis can explain many features of myeloproliferation. Interestingly, some features are associated with intracellular levels of mutated JAK2 (the "dosage hypothesis"). The mutation in JAK2 kinase is not an example of a genetic defect leading to a single disease, since it occurs in many other myeloid disorders, and probably represents a secondary hit in a multistep ongogenetic process. Nevertheless, it has changed the way we approach cMPD patients and has clarified many aspects of their biology.

Regulation of hematopoiesis in vitro and in vivo by invariant NKT cells.

Invariant natural killer T cells (iNKT cells) are a small subset of immunoregulatory T cells highly conserved in humans and mice. On activation by glycolipids presented by the MHC-like molecule CD1d, iNKT cells promptly secrete T helper 1 and 2 (Th1/2) cytokines but also cytokines with hematopoietic potential such as GM-CSF. Here, we show that the myeloid clonogenic potential of human hematopoietic progenitors is increased in the presence of glycolipid-activated, GM-CSF-secreting NKT cells; conversely, short- and long-term progenitor activity is decreased in the absence of NKT cells, implying regulation of hematopoiesis in both the presence and the absence of immune activation. In accordance with these findings, iNKT-cell-deficient mice display impaired hematopoiesis characterized by peripheral-blood cytopenias, reduced marrow cellularity, lower frequency of hematopoietic stem cells (HSCs), and reduced early and late hematopoietic progenitors. We also show that CD1d is expressed on human HSCs. CD1d-expressing HSCs display short- and long-term clonogenic potential and can present the glycolipid alpha-galactosylceramide to iNKT cells. Thus, iNKT cells emerge as the first subset of regulatory T cells that are required for effective hematopoiesis in both steady-state conditions and under conditions of immune activation.

Amifostine protects lymphocytes during radiotherapy and stimulates expansion of the CD95/Fas and CD31 expressing T-cells, in breast cancer patients.

A large body of experimental research supports the anti-neoplastic activity of cellular and humoral immunity. Disease and therapy-related immune suppression may be important on the treatment outcome or on the subsequent course of the malignant disease. The aim of the study was to investigate the efficacy of amifostine in preventing the immunological toxicity of post-operative radiotherapy (RT) in breast cancer patients. Using flow-cytometry, we examined comparatively the peripheral blood lymphocytic subpopulations in breast cancer patients undergoing conventional post-operative RT versus a hypofractionated accelerated RT scheme combined with amifostine (HypoARC) administration. Despite the higher radiation dose intensity delivered in the HypoARC group, a significant protection of CD4, CD8, CD19 and CD56 subtypes by amifostine was noted. We further focused on two interesting CD4/CD8 subpopulations involved in cellular apoptosis and trans-endothelial migration, namely the CD95/Fas and CD31 positive lymphocytes. Amifostine protected and induced expansion of these subtypes, which could contribute to the maintenance of a high burden of tumor infiltrating lymphocytes during therapy. It is suggested that amifostine effectively protects lymphocytes against RT, which may enhance the efficacy of the latter. The clinical impact of the CD95(+) and CD31(+) T-cell immunological modulation induced by amifostine requires further investigation.