Modulation of SIRT1 expression in different neurodegenerative models and human pathologies

We examined the expression of SIRT1 in several experimental paradigms of human pathologies. We used a neuroblastoma cell line (B65), neuronal primary cultures (hippocampus and cerebellar granule cells) and in vivo approaches in rat and senescence murine models (SAM). Cell cultures and rats were treated with several well-know neurotoxins, i.e. rotenone, MPP(+), kainate and 3-nitropropionic acid. Subsequently, SIRT1 expression was compared in these different paradigms of neurotoxicity. The pattern of expression of SIRT1 in proliferating cell cultures (B65) was different to that in quiescent cell cultures. In the murine model of senescence (senescence-accelerated mice prone, SAMP8), SIRT1 expression progressively decreased, while in the control strain (senescence-accelerated mice resistant, SAMR1) it increased. Finally, we studied human samples of Parkinson's disease (PD), dementia with Lewy bodies (DLB) and Huntington's diseases (HD). SIRT1 expression decreased dramatically in HD, but there were no significant changes in Parkinson-related illnesses. In conclusion, SIRT1 expression may be a good sensor of toxic neuronal processes.     

Modulation of neuronal mitochondrial membrane potential by the NMDA receptor: role of arachidonic acid

Activation of NMDA receptors in dissociated cerebellar granule cells reduced mitochondrial membrane potential (MMP), as measured by rhodamine 123 fluorescence in a flow cytometer. This effect was inhibited by several NMDA-receptor antagonists with the following rank order of potency: MK-801>PCP>TCP>dextrorphan>dichlorokynurenic acid>

Full-size image

-AP5>dextromethorphan. Neither spermine nor arcaine modified the NMDA-induced reduction in MMP, whereas ifenprodil and eliprodil inhibited this response in the micromolar range. The mechanism responsible for the alteration of MMP mediated by NMDA was studied. Mepacrine and dibucaine prevented the MMP reduction induced by NMDA, as did W₁₃ (calmodulin antagonist). In contrast, this effect was not blocked by cyclooxygenase or lipooxygenase inhibitors, H7 (a protein kinase C inhibitor) or nitroarginine (nitric oxide synthase inhibitor). These data suggest a direct interaction between NMDA-receptor activation and arachidonic acid formation, and indicate that NMDA receptor-mediated effect on MMP could involve arachidonic acid.     

Encouraging results with inolimomab (anti-IL-2 receptor) as treatment for refractory acute graft-versus-host disease.

Inolimomab [corrected] an anti-interleukin-2 receptor (anti-IL-2R) monoclonal antibody, may be useful in the treatment of steroid-refractory acute graft-versus-host disease (aGVHD) by inhibiting 1 of its putative immunopathogenic pathways. We retrospectively analyzed 40 consecutive patients who received inolimomab [corrected] as salvage treatment for steroid refractory aGVHD at a single institution between June 1999 and December 2004. Inolimomab [corrected] was given intravenously at a dose of 11 mg/d for 3 consecutive days, followed by 5.5 mg/d for 7 consecutive days and then 5.5 mg every other day for 5 doses. No infusion-related side effects were noted. Twenty-three patients (58%) responded, including 15 (38%) complete and 8 (20%) partial responses. Median overall survival was 294 days (58-996 days) for responders versus 14 days for nonresponders (P < .001), with a 1 year probability of 59% vs 0% for overall survival (P < .0001). Patients without gastrointestinal (GI) involvement showed a higher response rate (100% versus 50% for those without versus with GI involvement, P = .03) In addition, patients who showed some response by day 15 had a higher overall survival (73 +/- 12% vs 24 +/- 12%, respectively, P = .02). The results of this study suggest that inolimomab [corrected] may be an effective salvage therapy for patients with steroid-refractory aGVHD, particularly for those without GI disease, and supports further studies with this agent in prospective controlled trials.     

Intensive salvage chemotherapy for primary refractory or first relapsed adult acute lymphoblastic leukemia: results of a prospective trial.

BACKGROUND AND OBJECTIVE: Adults with primary refractory or relapsed acute lymphoblastic leukemia (ALL) have a very poor prognosis with current salvage chemotherapies. Complete remissions (CR) can be obtained with intensive regimens in 40-60% of cases, but they are short-lived. In an effort to obtain high CR rates and prolong their duration and achieve long-term survival in a substantial number of patients, we designed an intensive combination salvage regimen (RELAL-88). In this protocol, chemotherapy was to be followed by an allogeneic or autologous stem cell transplant (SCT) within three months from CR. DESIGN AND METHODS: Forty-five patients with primary refractory (n=17) or first relapsed ALL (n=28) were treated with the RELAL-88 five-day induction regimen comprising vindesine, mitoxantrone, cyclophosphamide, intermediate-dose Ara-C, prednisolone and methotrexate. Twenty-eight patients received granulocyte colony-stimulating factor (G-CSF), 16 patients from day 6 (early G-CSF group) and 12 from day 14 of therapy (delayed G-CSF group). RESULTS: Thirty-four patients (74%) achieved CR (95% CI 60-87), two died in aplasia due to infection and nine were non-responders. No pretreatment variable analyzed was predictive of the chance of obtaining CR. Recovery of neutrophils occurred at a median of 29 days from the start of chemotherapy without G-CSF and 20 days with G-CSF (p = 0.005), without differences between the early and late G-CSF groups. Non-hematologic side effects were usually well tolerated and consisted mainly of infections and mucositis. Twenty-three of 34 patients (68%) who achieved CR reached the planned SCT (nine autologous and 14 allogeneic). The median overall survival was 5.7 months, and the median disease-free survival for those achieving CR was 4.6 months. Of the variables analyzed for their influence on overall survival among the 34 patients who achieved CR, only the availability of an HLA-compatible sibling was associated with a prolonged survival (p = 0.03). INTERPRETATION AND CONCLUSIONS: The RELAL-88 intensive salvage regimen produces a very high rate of CR in poor-risk adult ALL. Non-hematologic toxicities were tolerable, and most eligible patients could undergo the planned SCT. G-CSF significantly shortened the period of neutropenia by about eight days, irrespective of whether it was started early or late after chemotherapy. However, as with other currently available salvage therapies, remissions were short-lived, and more effective post-remission treatment strategies are needed. In our experience, only allogeneic SCT offered the chance of long-term survival.     

Seven novel mutations in the adenosine deaminase (ADA) gene in patients with severe and delayed onset combined immunodeficiency: G74C,V129M,G140E,R149W,Q199P, 462delG,and E337del

The degree of immunodeficiency associated with deficiency of adenosine deaminase (ADA) is variable. Most patients are infants with severe combined immunodeficiency (SCID), but in about 20 percent immune dysfunction becomes manifest later in childhood ("delayed-onset"); several patients with "late" or "adult" onset of immune dysfunction have been diagnosed at 15–39 years. Over 40 ADA gene mutations have thus far been identified. To better define the genotype-phenotype relationship, we report 7 novel ADA mutations, including 5 missense mutations (G74C, V129M, G140E, R149W, Q199P) and two short deletions (462delG, E337del). These were identifed among 7 patients (3 with SCID and 4 with delayed-onset). A homozygote for 462delG had SCID, whereas patients homozygous or heterozygous for V129M had delayed-onset. Two other delayed-onset patients, one heterozygous for G74C and the other for Q199P, each had a second allele carrying the previously reported "severe" mutation G216R. These findings are consistent with previous observations suggesting that, in general, SCID occurs when both alleles eliminate ADA function, and a milder phenotype when at least one allele can supply a low level of function. Hum Mutat 11:482, 1998. © 1998 Wiley-Liss, Inc.     

Flow cytometric study of mitochondrial dysfunction after AMPA receptor activation

The effect of AMPA-receptor stimulation on MMP and on the concentration of intracellular calcium ([Ca²⁺]_i) was studied in dissociated CGC from rat pups, by flow cytometry. In the presence of cyclothiazide, AMPA induced a sodium-independent decrease in MMP up to 30.7 ± 2.5%. This effect was antagonized by CNQX and NBQX. Mepacrine and dibucaine reversed the effect of AMPA on MMP, suggesting that it is mediated by a release of arachidonic acid. AMPA alone induced a slight (about 7%) increase in [Ca²⁺]_i. In the presence of cyclothiazide, AMPA induced a concentration-dependent [Ca²⁺]_i increase up to 29.10 ± 2.10% that was not reversed by flunarizine. This increase was similar to that observed in a Na⁺-free medium, and was antagonized by CNQX and NBQX, but not by MK-801. Mitochondria play a key role in the modulation of [Ca²⁺]_i since a significant [Ca²⁺]_i increase was found in the presence of FCCP. On the other hand, the dantrolene-sensitive calcium pools do not participate in the [Ca²⁺]_i increase induced by stimulation of AMPA receptors. It is concluded that when AMPA-receptor desensitization is blocked, a decrease in MMP and an increase in [Ca²⁺]_i occurs, which could be additional events to potentiate neuronal cell death induced by glutamate. J. Neurosci. Res. 52:684–690, 1998. © 1998 Wiley-Liss, Inc.     

Concomitant chronic lymphocytic leukemia and acute myeloid leukemia with an uncommon immunophenotype

We report a case of simultaneous diagnosis of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML), in which the use of flow cytometry analysis allowed the demonstration of two different cell populations and the study of both immunophenotyping patterns with a large panel of monoclonal antibodies (MoAbs). CLL cells showed a typical immunophenotype with coexpression of B cell markers with CD5, CD23, CD43, and weak surface immunoglobulin light chain restriction expression, whereas the AML population had a very uncommon phenotype with expression of myeloid markers and CD56 and lack of expression of other natural killer (NK) antigens, CD34 and HLA-DR. After chemotherapeutic treatment of AML with two induction courses, the patient achieved complete remission of the AML with persistence of a CD19/CD5 positive population. After consolidation chemotherapy, this latter population was no longer detectable despite the presence of lymphoid nodules in a bone marrow biopsy. Six months after diagnosis, the patient relapsed with AML and died shortly afterwards. Am. J. Hematol. 56:281–287, 1997. © 1997 Wiley-Liss, Inc.     

m7FLIPI and targeted sequencing in high‐risk follicular lymphoma

Patients with follicular lymphoma (FL) refractory to front‐line immunochemotherapy (ICT) have a poor overall survival (OS). Gene mutation analysis may be more accurate than classical risk factors to pick out these patients before treatment. This study aimed to describe the prevalence of selected genetic mutations in a cohort of patients with high‐risk FL. Twenty‐five patients with FL refractory to front‐line ICT and 10 non‐refractory patients matched for age, sex, and FLIPI score were included. We sequenced 18 genes (custom targeted sequencing panel) previously reported to potentially have prognostic impact, including the seven genes necessary to determine m7FLIPI risk. The 35 patients had a median age of 62. The FLIPI and FLIPI2 were high in 27 (84%) and 14 (48%), respectively. Three‐year progression‐free survival (PFS) and OS probabilities were 25% (95% CI, 13%‐41%) and 53% (34%‐69%), respectively. There were 73 variants in the 18 genes among the 35 patients. The median number of mutations per patient was 1 (interquartile range, 0‐3). The most commonly mutated genes were CREBBP (11 of 35, 31%) and EP300 (10 of 35, 29%). EP300 mutations were associated with refractoriness to treatment (10 of 25 among refractory and 0 of 10 among non‐refractory). In conclusion, in this study, patients with high‐risk follicular lymphoma were genetically heterogeneous.