ALBERT

Description: As previously reported (Colombat, Blood2001;97:101), rituximab (4 weekly doses of 375mg/m²) can lead to high response rates (RR) and prolonged remissions with minimal toxicity as 1st line therapy for low tumor burden FL. We report the final analysis of a trial evaluating long term efficacy and safety of rituximab in untreated low tumor burden FL (GELF criteria). 49 patients (pts) were included in the initial trial (median age 52 yrs), 2 refused consent for the extended F/Up period, and 1 pt died at M12. Molecular bcl2-JH rearrangement was assessed throughout the study. The median F/up was 83.8 mths. Overall best RR, complete/unconfirmed RR and partial RR at D78 were 74%, 50% and 24% respectively. Median PFS was 23.5 mths for the study population. Median duration of response (34 responders at D78, i.e 6 weeks after the last rituximab dose) was 28.6 mths, but response was still maintained without any further treatment in 11 pts after 5 years (24%) and in 7 pts after 7 years (15%). 31/46 pts were bcl2 positive in blood and/or marrow samples before rituximab: 11 (35%) became negative at D50, and 20 remained positive (65%). Median PFS was 37 mths for bcl2-negative pts at D50, and 12 mths for patients remaining positive (p=0.018 Log-rank). Of the 7 pts with sustained response after 7 years, 5 were bcl2 positive at D0, 2/5 became negative at D50, and 5/5 were still negative at M84. At year 7, 4/46 pts have died (1 from myelodysplasia, 3 from NHL), 35/42 have progressed, and 7 have never progressed without any other treatment than the initial rituximab therapy. Time to progression was significantly longer in the bcl2-negative population at D50 (p= 0.018, Log-rank). Duration of response was not correlated with bcl2 status at D50, but was associated with ‘Best response CR/Cru’ (p=0.007 Log-rank). Long-term tolerance was good, with only 13 SAE observed in 13 pts during the additional 4 years of F/Up (4 surgeries for non NHL-related pathologies, 1 node biopsy, 1 sleep apnea syndrome, 1 ischemic cardiopathy, 2 deaths from NHL, 1 depression, 1 pneumonia, 1 erysipela, 1 bronchitis). This long-term update confirms that a single 4-dose rituximab treatment yields durable benefits without the toxicity of chemotherapy for pts with low burden FL : Median PFS of 23.5 mths for the cohort, 28.6 mths for responders and 37 mths for pts turning bcl2-negative at D50, 15% of pts have maintained their response after 7 years, (2bis) the quality (CR/Cru) of the initial response was associated with a longer response duration high overall survival is observed with 4 deaths/46 pts (8.6%).

Description: Recent studies have demonstrated that in peripheral lymphoid tissues of normal mice and healthy humans, 1% to 5% of αβ T-cell receptor–positive (TCR+) T cells are CD4−CD8− (double-negative [DN]) T cells, capable of down-regulating immune responses. However, the origin and developmental pathway of DN T cells is still not clear. In this study, by monitoring CD4 expression during T-cell proliferation and differentiation, we identified a new differentiation pathway for the conversion of CD4+ T cells to DN regulatory T cells. We showed that the converted DN T cells retained a stable phenotype after restimulation and that furthermore, the disappearance of cell-surface CD4 molecules on converted DN T cells was a result of CD4 gene silencing. The converted DN T cells were resistant to activation-induced cell death (AICD) and expressed a unique set of cell-surface markers and gene profiles. These cells were highly potent in suppressing alloimmune responses both in vitro and in vivo in an antigen-specific manner. Perforin was highly expressed by the converted DN regulatory T cells and played a role in DN T-cell–mediated suppression. Our findings thus identify a new differentiation pathway for DN regulatory T cells and uncover a new intrinsic homeostatic mechanism that regulates the magnitude of immune responses. This pathway provides a novel, cell-based, therapeutic approach for preventing allograft rejection.

Description: The role of the intrinsic coagulation system on the risk of myocardial infarction is unclear. In the Study of Myocardial Infarctions Leiden (SMILE) that included 560 men younger than age 70 with a first myocardial infarction and 646 control subjects, we investigated the risk of myocardial infarction for levels of factor XI (factor XIc) and factor XII (factor XIIc). Furthermore, the risks for factor VIII activity (factor VIIIc) and factor IX activity (factor IXc) were assessed. Factor XIc was 113.0% in patients compared with 109.8% in control subjects (difference, 3.2%; 95% CI, 1.1%-5.4%). The risk of myocardial infarction adjusted for age for men in the highest quintile compared with those in the lowest quintile was 1.8-fold increased (ORadj, 1.8; 95% CI, 1.2-2.7). In contrast, factor XIIc among patients with myocardial infarction was lower than in control subjects, respectively, 93.0% and 98.6% (difference, 5.6%; 95% CI, 3.3%-7.9%). The odds ratio of myocardial infarction for men in the highest quintile versus those in the lowest quintile was 0.4 (ORadj, 0.4; 95% CI, 0.2-0.5). The highest risk was found among men with both high factor XIc and low factor XIIc (analyses in tertiles: ORadj, 6.4; 95% CI, 2.2-18.0). Factor VIIIc increased the risk of myocardial infarction although not dose dependently. Factor IXc increased the risk; odds ratio of myocardial infarction for men in the highest quintile versus those in the lowest quintile was 3.2 (ORadj, 3.2; 95% CI, 2.0-5.1). Thus, factors XIc and XIIc have opposite and synergistic effects on the risk of myocardial infarction in men; factor VIIIc and factor IXc increase the risk.

Description: Zinc deficiency is common in adult sickle-cell disease (SCD) patients, due to continued hemolysis and hyperzincuria. Growth retardation, hypogonadism, and immune dysfunctions due to zinc deficiency have been described in SCD patients. Our studies show that zinc has not only anti-inflammatory functions, but is also an antioxidant. We have previously shown that zinc supplementation to adult SCD patients decreased the incidences of infection and hospital admissions. We hypothesize that zinc supplementation improves T-helper cell and vascular endothelial cell activation, and decreases oxidative stress and NF-κB activation in SCD patients. To test this hypothesis, we recruited 36 ambulatory SCD (homozygous) patients (ages 18–47 years, 11 males and 7 females in each group) and randomly divided these into 2 groups. One group (n=18) received 25 mg zinc as acetate orally thrice a day for 3 months. The other group (n=18) received placebo. All these patients were free of pain crisis for 3 months and were not receiving hydroxyurea. The results indicate that zinc supplemented group had decreased incidence of infection in comparison to the placebo group (Chi square analysis: p=0.017). After 3 months of zinc supplementation, the plasma zinc level increased. The anti-oxidant power increased and the plasma levels of NO, lipid peroxidation products (MDA+HAE), DNA oxidation product (8-OHdG), and sVCAM-1 decreased in the zinc supplemented group, compared to the placebo group (p

Description: The incidence of follicular lymphoma (FL) in industrialized countries has been increasing since the 1950s. Polymorphisms in genes encoding key enzymes controlling folate-methionine metabolism, including methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MS or MTR), serine hydroxymethyltransferase (SHMT), and thymidylate synthase (TS or TYMS), modify the risk of various cancers and possibly FL. This study specifically looks for an association between MTHFR, MTR, TYMS, and SHMT polymorphisms and the risk of FL. We carried out a case-control study with 172 patients diagnosed with FL and 206 control subjects. We report that the risk of FL was doubled by the association of one mutant allele at both MTHFR polymorphisms. Individuals with MTR 2756AA had 2-fold higher risk of FL, and subjects not having at least one TYMS 2R allele showed a 2-fold higher risk of FL. The MTR 2756AA genotype conferred a greater multivariate-adjusted relative risk of FL, and the risk was multiplied by almost 5 in the TYMS2R(-)/MTR 2756AA combination. In conclusion, common polymorphisms in key enzymes of the folate-methionine metabolism pathway result in an increased risk of FL and suggest that inadequate intake of dietary folate and other methyl donor nutrients may contribute to the development of this malignancy. (Blood. 2006;108:278-285)

Description: Leukostasis, a life-threatening complication of acute leukemia, occurs when leukemia cells obstruct the circulation of vital organs like the brain and lungs leading to intracranial hemorrhage or respiratory failure. Although the pathophysiology of leukostasis is poorly understood, an elevated concentration of circulating leukemia cells, pathologic adhesion, and decreased cell deformability are thought to play significant roles. Clinical deterioration can occur soon after chemotherapy is initiated, suggesting that chemotherapy itself may be a risk factor for leukostasis. To investigate the effects of chemotherapy on cell stiffness, we performed serial single cell deformability measurements with an atomic force microscope (AFM), a commonly used tool in nanoscience for imaging and characterizing mechanical properties of materials on a submicron level, and modified the AFM to operate in cell culture conditions at 37°C. Leukemia cells from patients with acute lymphoblastic leukemia and acute myeloid leukemia as well as leukemia cell lines were incubated with chemotherapeutic agents, and changes in cell stiffness were tracked over time with AFM as the cells underwent chemotherapy-induced cell death. In the presence of dexamethasone or daunorubicin, leukemia cells exhibited increases in stiffness by as much as two orders of magnitude. Cell stiffness appeared to increase before caspase activation and peaked after completion of cell death, and the rate at which cell stiffness increased was dependent on chemotherapy type. Stiffening with cell death was found to occur for all cell types and chemotherapies investigated and is due, at least in part, to dynamic changes in the actin cytoskeleton. This observed correlation between cell death and cell stiffening may partially explain why some leukemia patients develop leukostasis shortly after starting chemotherapy, and it suggests that leukocytoreduction should remain an important treatment for hyperleukocytosis in acute leukemia. Figure 1. Average apparent stiffness of dead (dark gray) leukemic cells exposed to chemotherapy is significantly higher compared to untreated (light gray) cells (n 〉 15, p 〈 0.05 for all comparisons of dead/untreated populations). (A) Primary ALL cells and lymphoid leukemic cell lines exposed to 1 μM dexamethasone (B) Primary AML and myeloid leukemic cell lines exposed to 1μM daunorubicin. Error bars are standard error. Figure 1. Average apparent stiffness of dead (dark gray) leukemic cells exposed to chemotherapy is significantly higher compared to untreated (light gray) cells (n 〉 15, p 〈 0.05 for all comparisons of dead/untreated populations). (A) Primary ALL cells and lymphoid leukemic cell lines exposed to 1 μM dexamethasone (B) Primary AML and myeloid leukemic cell lines exposed to 1μM daunorubicin. Error bars are standard error. Figure 2. Apparent stiffness of leukemic cells increases with progression of cell death. (A) A typical stiffness trace of a single M5 AML cell exposed to 1μM daunorubicin (circles). The apparent stiffness of a typical control cell remains relatively constant (triangles) and does not undergo apoptosis or cell death during the course of the experiment. Transition from open to filled shapres represents onset of cell death. Early apoptosis is defined as caspase 3 or 7 postivie staining and late apoptosis/dead is defined as Sytox Green (marker for cell membrane integrity loss) positive staining. (B) From the same patient sample, the average apparent stiffness of a population of late apoptotic/dead AML cells was significantly stiffer than early apoptopic cells and controls (n = 15, p〈 0.05). Error bars are standard error. Figure 2. Apparent stiffness of leukemic cells increases with progression of cell death. (A) A typical stiffness trace of a single M5 AML cell exposed to 1μM daunorubicin (circles). The apparent stiffness of a typical control cell remains relatively constant (triangles) and does not undergo apoptosis or cell death during the course of the experiment. Transition from open to filled shapres represents onset of cell death. Early apoptosis is defined as caspase 3 or 7 postivie staining and late apoptosis/dead is defined as Sytox Green (marker for cell membrane integrity loss) positive staining. (B) From the same patient sample, the average apparent stiffness of a population of late apoptotic/dead AML cells was significantly stiffer than early apoptopic cells and controls (n = 15, p〈 0.05). Error bars are standard error.

Description: FTY720, a potent immunomodulatory drug in phase 2/3 clinical trials, induces rapid and reversible sequestration of lymphocytes into secondary lymphoid organs, thereby preventing their migration to sites of inflammation. As prerequisite for its function, phosphorylation of FTY720 to yield a potent agonist of the sphingosine-1-phosphate receptor S1P1 is required in vivo, catalyzed by an as-yet-unknown kinase. Here, we report on the generation of sphingosine kinase 2 (SPHK2) knockout mice and demonstrate that this enzyme is essential for FTY720 phosphate formation in vivo. Consequently, administration of FTY720 does not induce lymphopenia in SPHK2-deficient mice. After direct dosage of FTY720 phosphate, lymphopenia is only transient in this strain, indicating that SPHK2 is constantly required to maintain FTY720 phosphate levels in vivo.

Description: The incorporation of blood-borne forms of tissue factor (TF) into a growing blood clot is necessary for normal fibrin generation and stabilization of the blood clot. Tissue factor pathway inhibitor (TFPI) is the primary physiologic inhibitor of tissue factor and is present within platelets. Expression of TFPI on the platelet surface may be the optimal location for it to abrogate blood-borne TF activity that incorporates within the blood clot, balancing the need for adequate hemostasis while preventing development of occlusive thrombosis. TFPI is produced by megakaryocytes but is not expressed on the platelet surface. Activation of platelets with thrombin receptor activation peptide does not cause release or surface expression of TFPI, demonstrating that TFPI is not stored within platelet α granules. TFPI is expressed on the platelet surface following dual-agonist activation with convulxin plus thrombin to produce coated platelets. In association with its expression on the surface of coated platelets TFPI is also released in microvesicles or as a soluble protein.