Impaired Brain Mitochondrial Bioenergetics in the Ts65Dn Mouse Model of Down Syndrome Is Restored by Neonatal Treatment with the Polyphenol 7,8-Dihydroxyflavone

Down syndrome (DS), a major genetic cause of intellectual disability, is characterized by numerous neurodevelopmental defects. Previous in vitro studies highlighted a relationship between bioenergetic dysfunction and reduced neurogenesis in progenitor cells from the Ts65Dn mouse model of DS, suggesting a critical role of mitochondrial dysfunction in neurodevelopmental alterations in DS. Recent in vivo studies in Ts65Dn mice showed that neonatal supplementation (Days P3–P15) with the polyphenol 7,8-dihydroxyflavone (7,8-DHF) fully restored hippocampal neurogenesis. The current study was aimed to establish whether brain mitochondrial bioenergetic defects are already present in Ts65Dn pups and whether early treatment with 7,8-DHF positively impacts on mitochondrial function. In the brain and cerebellum of P3 and P15 Ts65Dn pups we found a strong impairment in the oxidative phosphorylation apparatus, resulting in a deficit in mitochondrial ATP production and ATP content. Administration of 7,8-DHF (dose: 5 mg/kg/day) during Days P3–P15 fully restored bioenergetic dysfunction in Ts65Dn mice, reduced the levels of oxygen radicals and reinstated the hippocampal levels of PGC-1α. No pharmacotherapy is available for DS. From current findings, 7,8-DHF emerges as a treatment with a good translational potential for improving mitochondrial bioenergetics and, thus, mitochondria-linked neurodevelopmental alterations in DS.

Early appearance of dendritic alterations in neocortical pyramidal neurons of the Ts65Dn model of Down syndrome

Down syndrome (DS), which is due to triplication of chromosome 21, is constantly associated with intellectual disability (ID). ID can be ascribed to both neurogenesis impairment and dendritic pathology. These defects are replicated in the Ts65Dn mouse, a widely used model of DS. While neurogenesis impairment in DS is a fetal event, dendritic pathology occurs after the first postnatal months. Neurogenesis alterations across the lifespan have been extensively studied in the Ts65Dn mouse. In contrast, there is scarce information regarding dendritic alterations at early life stages in this and other models, although there is evidence for dendritic alterations in adult mouse models. Thus, the goal of the current study was to establish whether dendritic alterations are already present in the neonatal period in Ts65Dn mice. In Golgi-stained brains we quantified the dendritic arbors of layer II/III pyramidal neurons in the frontal cortex of Ts65Dn mice aged 2 (P2) and 8 (P8) days and their euploid littermates. In P2 Ts65Dn mice we found a moderate hypotrophy of the apical and collateral dendrites but a patent hypotrophy of the basal dendrites. In P8 Ts65Dn mice the distalmost apical branches were missing or reduced in number but there were no alterations in the collateral and basal dendrites. No genotype effects were detected on either somatic or dendritic spine density. This study shows dendritic branching defects that mainly involve the basal domain in P2 Ts65Dn mice, and the apical but not the other domains in P8 Ts65Dn mice. This suggests that dendritic defects may be related to dendritic compartment and age. The lack of a severe dendritic pathology in Ts65Dn pups is reminiscent of the delayed appearance of patent dendritic alterations in newborns with DS. This similarly highlights the usefulness of the Ts65Dn model for the study of the mechanisms underlying dendritic alterations in DS and the design of possible therapeutic interventions.

Obstructive sleep apneas naturally occur in mice during REM sleep and are highly prevalent in a mouse model of Down syndrome

STUDY OBJECTIVES

The use of mouse models in sleep apnea study is limited by the belief that central (CSA) but not obstructive sleep apneas (OSA) occur in rodents. We aimed to develop a protocol to investigate the presence of OSAs in wild-type mice and, then, to apply it to a validated model of Down syndrome (Ts65Dn), a human pathology characterized by a high incidence of OSAs.

METHODS

In a pilot study, nine C57BL/6J wild-type mice were implanted with electrodes for electroencephalography (EEG), neck electromyography (nEMG), and diaphragmatic activity (DIA), and then placed in a whole-body-plethysmographic (WBP) chamber for 8 h during the rest (light) phase to simultaneously record sleep and breathing activity. CSA and OSA were discriminated on the basis of WBP and DIA signals recorded simultaneously. The same protocol was then applied to 12 Ts65Dn mice and 14 euploid controls.

RESULTS

OSAs represented about half of the apneic events recorded during rapid-eye-movement-sleep (REMS) in each experimental group, while the majority of CSAs were found during non-rapid eye movement sleep. Compared with euploid controls, Ts65Dn mice had a similar total occurrence rate of apneic events during sleep, but a significantly higher occurrence rate of OSAs during REMS, and a significantly lower occurrence rate of CSAs during NREMS.

CONCLUSIONS

Mice physiologically exhibit both CSAs and OSAs. The latter appear almost exclusively during REMS, and are highly prevalent in Ts65Dn. Mice may, thus, represent a useful model to accelerate the understanding of the pathophysiology and genetics of sleep-disordered breathing and to help the development of new therapies.

Early appearance of developmental alterations in the dendritic tree of the hippocampal granule cells in the Ts65Dn model of Down syndrome

Down syndrome (DS), a genetic condition caused by triplication of chromosome 21, is characterized by alterations in various cognitive domains, including hippocampus-dependent memory functions, starting from early life stages. The major causes of intellectual disability in DS are prenatal neurogenesis alterations followed by impairment of dendritic development in early infancy. While there is evidence that the Ts65Dn mouse, the most widely used model of DS, exhibits dendritic alterations in adulthood, no studies are available regarding the onset of dendritic pathology. The goal of the current study was to establish whether this model exhibits early dendritic alterations in the hippocampus, a region whose function is severely damaged in DS. To this purpose, in Golgi-stained brains, we evaluated the dendritic arborization and dendritic spines of the granule cells of the hippocampal dentate gyrus in Ts65Dn mice aged 8 (P8) and 15 (P15) days. While P15 Ts65Dn mice exhibited a notably hypotrophic dendritic arbor and a reduced spine density, P8 mice exhibited a moderate reduction in the number of dendritic ramifications and no differences in spine density in comparison with their euploid counterparts. Both in P8 and P15 mice, spines were longer and had a longer neck, suggesting possible alterations in synaptic function. Moreover, P8 and P15 Ts65Dn mice had more thin spines and fewer stubby spines in comparison with euploid mice. Our study provides novel evidence on the onset of dendritic pathology, one of the causes of intellectual disability in DS, showing that it is already detectable in the dentate gyrus of Ts65Dn pups. This evidence strengthens the suitability of this model of DS as a tool to study dendritic pathology in DS and to test the efficacy of early therapeutic interventions aimed at ameliorating hippocampal development and, therefore, memory functions in children with DS.

Neonatal therapy with clenbuterol and salmeterol restores spinogenesis and dendritic complexity in the dentate gyrus of the Ts65Dn model of Down syndrome

Down syndrome (DS), a neurodevelopmental disorder caused by triplication of chromosome 21, is characterized by intellectual disability. In DS, defective neurogenesis causes an overall reduction in the number of neurons populating the brain and defective neuron maturation causes dendritic hypotrophy and reduction in the density of dendritic spines. No effective therapy currently exists for the improvement of brain development in individuals with DS. Drug repurposing is a strategy for identifying new medical use for approved drugs. A drug screening campaign showed that the β2-adrenergic receptor (β2-AR) agonists clenbuterol hydrochloride (CLEN) and salmeterol xinafoate (SALM) increase the proliferation rate of neural progenitor cells from the Ts65Dn model of DS. The goal of the current study was to establish their efficacy in vivo, in the Ts65Dn model. We found that, at variance with the in vitro experiments, treatment with CLEN or SALM did not restore neurogenesis in the hippocampus of Ts65Dn mice treated during the postnatal (P) period P3-P15. In Ts65Dn mice treated with CLEN or SALM, however, dendritic spine density and dendritic arborization of the hippocampal granule cells were restored and the lowest dose tested here (0.01 mg/kg/day) was sufficient to elicit these effects. CLEN and SALM are used in children as therapy for asthma and, importantly, they pass the blood-brain barrier. Our study suggests that treatment with these β2-AR agonists may be a therapy of choice in order to correct dendritic development in DS but is not suitable to rescue neurogenesis.

Subicular hypotrophy in fetuses with Down syndrome and in the Ts65Dn model of Down syndrome

Intellectual disability in Down syndrome (DS) has been attributed to neurogenesis impairment during fetal brain development. Consistently with explicit memory alterations observed in children with DS, fetuses with DS exhibit neurogenesis impairment in the hippocampus, a key region involved in memory formation and consolidation. Recent evidence suggests that the subiculum plays a unique role in memory retrieval, a process that is also altered in DS. While much attention has been devoted to the hippocampus, there is a striking lack of information regarding the subiculum of individuals with DS and DS models. In order to fill this gap, in the current study, we examined the subiculum of fetuses with DS and of the Ts65Dn mouse model of DS. We found that in fetuses with DS (gestational week: 17-21), the subiculum had a reduced thickness, a reduced cell density, a reduced density of progenitor cells in the ventricular zone, a reduced percentage of neurons, and an increased percentage of astrocytes and of cells immunopositive for calretinin-a protein expressed by inhibitory interneurons. Similarly to fetuses with DS, the subiculum of neonate Ts65Dn mice was reduced in size, had a reduced number of neurons and a reduced number of proliferating cells. Results suggest that the developmental defects in the subiculum of fetuses with DS may underlie impairment in recall memory and possibly other functions played by the subiculum. The finding that the subiculum of the Ts65Dn mouse exhibits neuroanatomical defects resembling those seen in fetuses with DS further validates the use of this model for preclinical studies.

Lithium Restores Age-related Olfactory Impairment in the Ts65Dn Mouse Model of Down Syndrome

BACKGROUND & OBJECTIVE

Down syndrome, a genetic condition caused by triplication of chromosome 21, is characterized by widespread neurogenesis reduction and cognitive impairment. Unlike other brain functions, smell is not impaired at early life stages and olfactory deterioration begins to appear in adulthood. Similarly to individuals with Down syndrome, in the Ts65Dn mouse model of Down syndrome smell function is normal at early life stages. Smell impairment only appears in adulthood associated with a reduction in the number of new granule neurons migrated to the olfactory bulb from the subventricular zone. Based on evidence that lithium positively impacts neurogenesis, the goal of current study was to establish whether treatment with lithium restores olfactory bulb neurogenesis and olfactory performance in middle-aged Ts65Dn mice.

METHOD

Euploid and Ts65Dn mice aged 13 months were treated with lithium chow or control chow for one month. Before the end of treatment, mice were injected with BrdU, in order to label proliferating cells. Results showed that in Ts65Dn mice lithium treatment restored the number of neural precursor cells in the subventricular zone of the lateral ventricle, rostral migratory stream and olfactory bulb. This effect was accompanied by restoration of olfactory performance. Unlike in olfactory neurogenic regions, treatment had no neurogenesis-enhancing effect on the subgranular zone of the hippocampal dentate gyrus, indicating that lithium has no generalized positive effect on the brain.

CONCLUSION

Results suggest that lithium may have a positive impact in brain disorders that, similarly to Down syndrome, are characterized by olfactory decline and neurogenesis impairment in the subventricular zone.

Abnormal development of the inferior temporal region in fetuses with Down syndrome

Down syndrome (DS) is a genetic condition associated with impairment in several cognitive domains. Previous evidence showed a notable neurogenesis reduction in the hippocampal region of DS fetuses, which may account for the impairment of declarative memory that characterizes DS starting from early life stages. The fusiform gyrus (FG) and the inferior temporal gyrus (ITG) play a key role in visual recognition memory, a function that is impaired in children and adults with DS. The goal of the current study was to establish whether fetuses with DS (17-21 weeks of gestation) exhibit neuroanatomical alterations in the FG and ITG that may underlie recognition memory impairment. We found that the FG and ITG of fetuses with DS had a reduced thickness and fewer cells in comparison with euploid fetuses. Moreover, DS fetuses had fewer cells expressing the neuronal marker NeuN than euploid fetuses, but a similar number of cells expressing the astrocytic marker GFAP and, consequently, a higher percentage of astrocytes. Immunohistochemistry for calretinin (CR), a marker of GABAergic interneurons, showed that in DS fetuses the ratio of CR-positive vs. CR-negative cells was greater than in euploid fetuses, both in the FG (177%) and ITG (161%). An increased ratio of CR-positive vs. CR-negative cells was also found in the entorhinal cortex, hippocampus and dentate gyrus. Results provide novel evidence that the FG and ITG of DS fetuses exhibit numerous developmental defects. These defects may underlie the functional alterations in visual recognition memory observed in children with DS.

Treatment with corn oil improves neurogenesis and cognitive performance in the Ts65Dn mouse model of Down syndrome

Individuals with Down syndrome (DS), a genetic condition due to triplication of Chromosome 21, are characterized by intellectual disability that worsens with age. Since impairment of neurogenesis and dendritic maturation are very likely key determinants of intellectual disability in DS, interventions targeted to these defects may translate into a behavioral benefit. While most of the neurogenesis enhancers tested so far in DS mouse models may pose some caveats due to possible side effects, substances naturally present in the human diet may be regarded as therapeutic tools with a high translational impact. Linoleic acid and oleic acid are major constituents of corn oil that positively affect neurogenesis and neuron maturation. Based on these premises, the goal of the current study was to establish whether treatment with corn oil improves hippocampal neurogenesis and hippocampus-dependent memory in the Ts65Dn model of DS. Four-month-old Ts65Dn and euploid mice were treated with saline or corn oil for 30 days. Evaluation of behavior at the end of treatment showed that Ts65Dn mice treated with corn oil underwent a large improvement in hippocampus-dependent learning and memory. Evaluation of neurogenesis and dendritogenesis showed that in treated Ts65Dn mice the number of new granule cells of the hippocampal dentate gyrus and their dendritic pattern became similar to those of euploid mice. In addition, treated Ts65Dn mice underwent an increase in body and brain weight. This study shows for the first time that fatty acids have a positive impact on the brain of the Ts65Dn mouse model of DS. These results suggest that a diet that is rich in fatty acids may exert beneficial effects on cognitive performance in individuals with DS without causing adverse effects.

Ophthalmological Aspects in Allogenic Bone Marrow Transplantation: Sjögren-Like Syndrome in Graft-Versus-Host Disease

PURPOSE

A major complication of allogenic bone marrow transplantation (BMT) is graft-versus-host disease (GVHD), characterized principally by involvement of the eyes, producing a Sjögren-like syndrome (SLS). This study assessed the predictive role of the eye involvement in the onset of GVHD.

METHODS

Thirty-five patients transplanted for hematological malignancies were routinely examined for ocular manifestation of dry eye. Examination includes the Schirmer I test, break-up time, Lissamine Green staining, fluorescein test, lactoferrin test and impression cytology. A threshold was established for quantitative analysis of SLS.

RESULTS

Fifteen of 35 patients (40%) developed SLS during long-term follow-up. Ten of these (77%) developed acute or chronic GVHD.

CONCLUSIONS

The possible etiology of SLS includes three factors: total body irradiation, ocular toxicity of chemotherapy and GVHD. A correlation was found between poor-prognosis GVHD and the occurrence of SLS.

Neurogenesis impairment: An early developmental defect in Down syndrome

Down syndrome (DS) is characterized by brain hypotrophy and intellectual disability starting from early life stages. Accumulating evidence shows that the phenotypic features of the DS brain can be traced back to the fetal period since the DS brain exhibits proliferation potency reduction starting from the critical time window of fetal neurogenesis. This defect is worsened by the fact that neural progenitor cells exhibit reduced acquisition of a neuronal phenotype and an increase in the acquisition of an astrocytic phenotype. Consequently, the DS brain has fewer neurons in comparison with the typical brain. Although apoptotic cell death may be increased in DS, this does not seem to be the major cause of brain hypocellularity. Evidence obtained in brains of individuals with DS, DS-derived induced pluripotent stem cells (iPSCs), and DS mouse models has provided some insight into the mechanisms underlying the developmental defects due to the trisomic condition. Although many triplicated genes may be involved, in the light of the studies reviewed here, DYRK1A, APP, RCAN1 and OLIG1/2 appear to be particularly important determinants of many neurodevelopmental alterations that characterize DS because their triplication affects both the proliferation and fate of neural precursor cells as well as apoptotic cell death. Based on the evidence reviewed here, pathways downstream to these genes may represent strategic targets, for the design of possible interventions.

'Real-life' report on the management of chronic GvHD in the Gruppo Italiano Trapianto Midollo Osseo (GITMO)

Several guidelines have been published about management of chronic GvHD (cGvHD), but the clinical practice still remains demanding. The Gruppo Italiano Trapianto di Midollo Osseo (GITMO) has planned a prospective observational study on cGvHD, supported by a dedicated software, including the updated recommendations. In view of this study, two surveys have been conducted, focusing the management of cGvHD and ancillary therapy in cGvHD, to address the current 'real life' situation. The two surveys were sent to all 57 GITMO centers, performing allografting in Italy; the response rate was 57% and 66% of the interviewed centers, respectively. The first survey showed a great disparity especially regarding steroid-refractory cGvHD, although extracorporeal photo-apheresis resulted as the most indicated treatment in this setting. Another challenging issue was the strategy for tapering steroid: our survey showed a great variance, and this disagreement could be a real bias in evaluating outcomes in prospective studies. As for the second survey, the results suggest that the ancillary treatments are not standardized in many centers. All responding centers reported a strong need to standardize management of cGvHD and to participate in prospective trials. Before starting observational and/or interventional studies, a detailed knowledge of current practice should be encouraged.

Epigallocatechin gallate: A useful therapy for cognitive disability in Down syndrome?

Neurodevelopmental alterations and cognitive disability are constant features of Down syndrome (DS), a genetic condition due to triplication of chromosome 21. DYRK1A is one of the triplicated genes that is thought to be strongly involved in brain alterations. Treatment of Dyrk1A transgenic mice with epigallocatechin gallate (EGCG), an inhibitor of DYRK1A, improves cognitive performance, suggesting that EGCG may represent a suitable treatment of DS. Evidence in the Ts65Dn mouse model of DS shows that EGCG restores hippocampal development, although this effect is ephemeral. Other studies, however, show no effects of treatment on hippocampus-dependent memory. On the other hand, a pilot study in young adults with DS shows that EGCG transiently improves some aspects of memory. Interestingly, EGCG plus cognitive training engenders effects that are more prolonged. Studies in various rodent models show a positive impact of EGCG on brain and behavior, but other studies show no effect. In spite of these discrepancies, possibly due to heterogeneity of protocols/timing/species, EGCG seems to exert some beneficial effects on the brain. It is possible that protocols of periodic EGCG administration to individuals with DS (alone or in conjunction with other treatments) may prevent the disappearance of its effects.

Timing of therapies for Down syndrome: the sooner, the better

Intellectual disability (ID) is the unavoidable hallmark of Down syndrome (DS), with a heavy impact on public health. Accumulating evidence shows that DS is characterized by numerous neurodevelopmental alterations among which the reduction of neurogenesis, dendritic hypotrophy and connectivity alterations appear to play a particularly prominent role. Although the mechanisms whereby gene triplication impairs brain development in DS have not been fully clarified, it is theoretically possible to correct trisomy-dependent defects with targeted pharmacotherapies. This review summarizes what we know about the effects of pharmacotherapies during different life stages in mouse models of DS. Since brain alterations in DS start to be present prenatally, the prenatal period represents an optimum window of opportunity for therapeutic interventions. Importantly, recent studies clearly show that treatment during the prenatal period can rescue overall brain development and behavior and that this effect outlasts treatment cessation. Although late therapies are unlikely to exert drastic changes in the brain, they may have an impact on the hippocampus, a brain region where neurogenesis continues throughout life. Indeed, treatment at adult life stages improves or even rescues hippocampal neurogenesis and connectivity and hippocampal-dependent learning and memory, although the duration of these effects still remains, in the majority of cases, a matter of investigation. The exciting discovery that trisomy-linked brain abnormalities can be prevented with early interventions gives us reason to believe that treatments during pregnancy may rescue brain development in fetuses with DS. For this reason we deem it extremely important to expedite the discovery of additional therapies practicable in humans in order to identify the best treatment/s in terms of efficacy and paucity of side effects. Prompt achievement of this goal is the big challenge for the scientific community of researchers interested in DS.

Inhibition of APP gamma-secretase restores Sonic Hedgehog signaling and neurogenesis in the Ts65Dn mouse model of Down syndrome

Neurogenesis impairment starting from early developmental stages is a key determinant of intellectual disability in Down syndrome (DS). Previous evidence provided a causal relationship between neurogenesis impairment and malfunctioning of the mitogenic Sonic Hedgehog (Shh) pathway. In particular, excessive levels of AICD (amyloid precursor protein intracellular domain), a cleavage product of the trisomic gene APP (amyloid precursor protein) up-regulate transcription of Ptch1 (Patched1), the Shh receptor that keeps the pathway repressed. Since AICD results from APP cleavage by γ-secretase, the goal of the current study was to establish whether treatment with a γ-secretase inhibitor normalizes AICD levels and restores neurogenesis in trisomic neural precursor cells. We found that treatment with a selective γ-secretase inhibitor (ELND006; ELN) restores proliferation in neurospheres derived from the subventricular zone (SVZ) of the Ts65Dn mouse model of DS. This effect was accompanied by reduction of AICD and Ptch1 levels and was prevented by inhibition of the Shh pathway with cyclopamine. Treatment of Ts65Dn mice with ELN in the postnatal period P3–P15 restored neurogenesis in the SVZ and hippocampus, hippocampal granule cell number and synapse development, indicating a positive impact of treatment on brain development. In addition, in the hippocampus of treated Ts65Dn mice there was a reduction in the expression levels of various genes that are transcriptionally regulated by AICD, including APP, its origin substrate. Inhibitors of γ-secretase are currently envisaged as tools for the cure of Alzheimer's disease because they lower βamyloid levels. Current results provide novel evidence that γ-secretase inhibitors may represent a strategy for the rescue of neurogenesis defects in DS.

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Derangement of the mitogenic Shh pathway reduces neurogenesis in Down syndrome (DS).

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APP triplication causes excessive formation of its cleavage products AICD.

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AICD causes excessive transcription of Ptch1, the repressor of the Shh pathway.

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ELND006, a gamma secretase inhibitor, reduces AICD levels and Ptch1 expression.

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Treatment with ELND006 restores neurogenesis in the Ts65Dn mouse model of DS.

Prenatal pharmacotherapy rescues brain development in a Down's syndrome mouse model

Intellectual impairment is a strongly disabling feature of Down's syndrome, a genetic disorder of high prevalence (1 in 700-1000 live births) caused by trisomy of chromosome 21. Accumulating evidence shows that widespread neurogenesis impairment is a major determinant of abnormal brain development and, hence, of intellectual disability in Down's syndrome. This defect is worsened by dendritic hypotrophy and connectivity alterations. Most of the pharmacotherapies designed to improve cognitive performance in Down's syndrome have been attempted in Down's syndrome mouse models during adult life stages. Yet, as neurogenesis is mainly a prenatal event, treatments aimed at correcting neurogenesis failure in Down's syndrome should be administered during pregnancy. Correction of neurogenesis during the very first stages of brain formation may, in turn, rescue improper brain wiring. The aim of our study was to establish whether it is possible to rescue the neurodevelopmental alterations that characterize the trisomic brain with a prenatal pharmacotherapy with fluoxetine, a drug that is able to restore post-natal hippocampal neurogenesis in the Ts65Dn mouse model of Down's syndrome. Pregnant Ts65Dn females were treated with fluoxetine from embryonic Day 10 until delivery. On post-natal Day 2 the pups received an injection of 5-bromo-2-deoxyuridine and were sacrificed after either 2 h or after 43 days (at the age of 45 days). Untreated 2-day-old Ts65Dn mice exhibited a severe neurogenesis reduction and hypocellularity throughout the forebrain (subventricular zone, subgranular zone, neocortex, striatum, thalamus and hypothalamus), midbrain (mesencephalon) and hindbrain (cerebellum and pons). In embryonically treated 2-day-old Ts65Dn mice, precursor proliferation and cellularity were fully restored throughout all brain regions. The recovery of proliferation potency and cellularity was still present in treated Ts65Dn 45-day-old mice. Moreover, embryonic treatment restored dendritic development, cortical and hippocampal synapse development and brain volume. Importantly, these effects were accompanied by recovery of behavioural performance. The cognitive deficits caused by Down's syndrome have long been considered irreversible. The current study provides novel evidence that a pharmacotherapy with fluoxetine during embryonic development is able to fully rescue the abnormal brain development and behavioural deficits that are typical of Down's syndrome. If the positive effects of fluoxetine on the brain of a mouse model are replicated in foetuses with Down's syndrome, fluoxetine, a drug usable in humans, may represent a breakthrough for the therapy of intellectual disability in Down's syndrome.

Age-related impairment of olfactory bulb neurogenesis in the Ts65Dn mouse model of Down syndrome

Down syndrome (DS) is a genetic condition caused by triplication of chromosome 21. Widespread neurogenesis reduction during brain development underlies the numerous neurological defects of DS. These defects start to manifest themselves at birth and worsen with age. However, unlike other brain functions, smell is impaired only at advanced life stages, suggesting preservation of olfactory bulb neurogenesis up to adulthood. To clarify this issue, in the current study we examined olfactory bulb (OB) neurogenesis and olfactory function by exploiting the Ts65Dn mouse, a widely used model of DS. We found that in young (15-day-old) Ts65Dn mice, in spite of a reduced proliferation rate in the subventricular zone (SVZ) in comparison with euploid mice, the number of neuroblasts traveling in the rostral migratory stream (RMS), en route to the OB, and the number of new granule neurons added to the OB were similar to those of euploid mice. In mid-age (13-month-old) Ts65Dn mice, however, the proliferation rate in the SVZ was more severely reduced in comparison with euploid mice and the number of neuroblasts in the RMS and new granule neurons added to the OB underwent a reduction. While in young Ts65Dn mice the olfactory function, assessed with the buried food pellet test, was similar to that of euploid mice, in mid-age mice it was significantly impaired. Taken together, results suggest that an age-related reduction in the renewal of OB granule cells may underlie the age-related smell impairment in DS.

Identification of prognostic factors predicting outcome in Hodgkin's lymphoma patients relapsing after autologous stem cell transplantation

BACKGROUND

High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is the standard of care for patients with relapsed Hodgkin's lymphoma (HL). However, there is currently little information on the predictors of outcome for patients whose disease recurs after ASCT.

METHODS

Five hundred and eleven adult patients with relapsed HL after ASCT from EBMT-GITMO databases were reviewed.

RESULTS

Treatments administered following ASCT failure included conventional chemotherapy and/or radiotherapy in 294 (64%) patients, second ASCT in 35 (8%), and alloSCT in 133 (29%). After a median follow-up of 49 months, overall survival (OS) was 32% at 5 years. Independent risk factors for OS were early relapse (<6 months) after ASCT, stage IV, bulky disease, poor performance status (PS), and age ≥50 years at relapse. For patients with no risk factors OS at 5 years was 62% compared with 37% and 12% for those having 1 and ≥2 factors, respectively. This score was also predictive for outcome in each group of rescue treatment after ASCT failure.

CONCLUSION(S)

Early relapse, stage IV, bulky disease, poor PS, and age ≥50 years at ASCT failure are relevant factors for outcome that may help to understand the results of different therapeutic approaches.

Identification of prognostic factors predicting outcome in Hodgkin's lymphoma patients relapsing after autologous stem cell transplantation

BACKGROUND

High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) is the standard of care for patients with relapsed Hodgkin's lymphoma (HL). However, there is currently little information on the predictors of outcome for patients whose disease recurs after ASCT.

METHODS

Five hundred and eleven adult patients with relapsed HL after ASCT from EBMT-GITMO databases were reviewed.

RESULTS

Treatments administered following ASCT failure included conventional chemotherapy and/or radiotherapy in 294 (64%) patients, second ASCT in 35 (8%), and alloSCT in 133 (29%). After a median follow-up of 49 months, overall survival (OS) was 32% at 5 years. Independent risk factors for OS were early relapse (<6 months) after ASCT, stage IV, bulky disease, poor performance status (PS), and age ≥50 years at relapse. For patients with no risk factors OS at 5 years was 62% compared with 37% and 12% for those having 1 and ≥2 factors, respectively. This score was also predictive for outcome in each group of rescue treatment after ASCT failure.

CONCLUSION(S)

Early relapse, stage IV, bulky disease, poor PS, and age ≥50 years at ASCT failure are relevant factors for outcome that may help to understand the results of different therapeutic approaches.

Pharmacotherapy with fluoxetine restores functional connectivity from the dentate gyrus to field CA3 in the Ts65Dn mouse model of down syndrome

Down syndrome (DS) is a high-incidence genetic pathology characterized by severe impairment of cognitive functions, including declarative memory. Impairment of hippocampus-dependent long-term memory in DS appears to be related to anatomo-functional alterations of the hippocampal trisynaptic circuit formed by the dentate gyrus (DG) granule cells - CA3 pyramidal neurons - CA1 pyramidal neurons. No therapies exist to improve cognitive disability in individuals with DS. In previous studies we demonstrated that pharmacotherapy with fluoxetine restores neurogenesis, granule cell number and dendritic morphology in the DG of the Ts65Dn mouse model of DS. The goal of the current study was to establish whether treatment rescues the impairment of synaptic connectivity between the DG and CA3 that characterizes the trisomic condition. Euploid and Ts65Dn mice were treated with fluoxetine during the first two postnatal weeks and examined 45-60 days after treatment cessation. Untreated Ts65Dn mice had a hypotrophyc mossy fiber bundle, fewer synaptic contacts, fewer glutamatergic contacts, and fewer dendritic spines in the stratum lucidum of CA3, the terminal field of the granule cell projections. Electrophysiological recordings from CA3 pyramidal neurons showed that in Ts65Dn mice the frequency of both mEPSCs and mIPSCs was reduced, indicating an overall impairment of excitatory and inhibitory inputs to CA3 pyramidal neurons. In treated Ts65Dn mice all these aberrant features were fully normalized, indicating that fluoxetine can rescue functional connectivity between the DG and CA3. The positive effects of fluoxetine on the DG-CA3 system suggest that early treatment with this drug could be a suitable therapy, possibly usable in humans, to restore the physiology of the hippocampal networks and, hence, memory functions.

Early pharmacotherapy with fluoxetine rescues dendritic pathology in the Ts65Dn mouse model of down syndrome

Down syndrome DS is a genetic pathology characterized by brain hypotrophy and severe cognitive impairment. Although defective neurogenesis is an important determinant of mental disability, a severe dendritic pathology appears to be an equally important factor. A previous study showed that fluoxetine, a selective serotonin reuptake inhibitor, fully restores neurogenesis in the Ts65Dn mouse model of DS. The goal of the current study was to establish whether fluoxetine also restores dendritic development. In mice aged 45 days, treated with fluoxetine in the postnatal period P3-P15, we examined the dendritic arbor of the granule cells of the dentate gyrus (DG). The granule cells of trisomic mice had a severely hypotrophic dendritic arbor, fewer spines and a reduced innervation than euploid mice. Treatment with fluoxetine fully restored all these defects. In Ts65Dn mice, we found reduced levels of serotonin that were restored by treatment. Results show that a pharmacotherapy with fluoxetine is able to rescue not only the number of granule neurons but also their "quality" in terms of correct maturation and connectivity. These findings strongly suggest that fluoxetine may be a drug of choice for the improvement of the major defects in the DS brain and, possibly, of mental retardation.

Autologous haematopoietic stem cell transplantation with an intermediate intensity conditioning regimen in multiple sclerosis: the Italian multi-centre experience

BACKGROUND

Over recent years numerous patients with severe forms of multiple sclerosis (MS) refractory to conventional therapies have been treated with intense immunosuppression followed by autologous haematopoietic stem cell transplantation (AHSCT). The clinical outcome and the toxicity of AHSCT can be diverse, depending on the various types of conditioning protocols and on the disease phase.

OBJECTIVES

To report the Italian experience on all the consecutive patients with MS treated with AHSCT with an intermediate intensity conditioning regimen, named BEAM/ATG, in the period from 1996 to 2008.

METHODS

Clinical and magnetic resonance imaging outcomes of 74 patients were collected after a median follow-up period of 48.3 (range = 0.8-126) months.

RESULTS

Two patients (2.7%) died from transplant-related causes. After 5 years, 66% of patients remained stable or improved. Among patients with a follow-up longer than 1 year, eight out of 25 subjects with a relapsing-remitting course (31%) had a 6-12 months confirmed Expanded Disability Status Scale improvement > 1 point after AHSCT as compared with one out of 36 (3%) patients with a secondary progressive disease course (p = 0.009). Among the 18 cases with a follow-up longer than 7 years, eight (44%) remained stable or had a sustained improvement while 10 (56%), after an initial period of stabilization or improvement with median duration of 3.5 years, showed a slow disability progression.

CONCLUSIONS

This study shows that AHSCT with a BEAM/ATG conditioning regimen has a sustained effect in suppressing disease progression in aggressive MS cases unresponsive to conventional therapies. It can also cause a sustained clinical improvement, especially if treated subjects are still in the relapsing-remitting phase of the disease.

Successful tigecycline lock therapy in a Lactobacillus rhamnosus catheter-related bloodstream infection

INTRODUCTION

Catheter-related bloodstream infections very often involve the premature removal of long-term intravascular devices (LTID). The antibiotic lock therapy (ALT) represents a conservative approach to the treatment of uncomplicated infections of tunneled LTID when catheter removal is not a feasible option.

CASE REPORT

We present here the first reported case of tunneled LTID bloodstream infection due to a multidrug resistant Lactobacillus rhamnosus. The patient, who had large granular lymphocytic leukemia, was successfully treated with systemic tigecycline therapy and lock therapy.

CONCLUSION

Our results confirm ALT as a valid catheter-salvage strategy for the treatment of CRBSIs in clinically stable patients when catheter removal is not a feasible option, tigecycline appear to be a good option.

Impact of environmental enrichment on neurogenesis in the dentate gyrus during the early postnatal period

Accumulating evidence shows that environmental enrichment increases neurogenesis in the adult hippocampal dentate gyrus. The goal of the current study was to examine the effect of environmental enrichment on hippocampal neurogenesis during early life stages. We used as an animal model the guinea pig, a precocious rodent that is early independent from maternal care. Animals were assigned to either a standard (control) or an enriched environment a few days after birth (P5-P6). Between P14 and P17 animals received one daily bromodeoxyuridine (BrdU) injection, to label dividing cells, and were sacrificed either on P18, to evaluate cell proliferation or on P45, to evaluate cell survival and differentiation. In 18-day old enriched animals, there was a larger number of BrdU-positive cells compared to that found in controls. At P45, enriched animals had more surviving cells and more cells with a neuronal phenotype than controls. Unbiased stereology revealed that enriched animals had more granule cells (+37% at P18 and +31% at P45). Results show that environmental enrichment in the early postnatal period notably increases cell proliferation and survival, with a large increase in the number of neurons forming the granule cell layer. The impact of environmental enrichment in the early postnatal period emphasizes the relevance of extrinsic factors in the modulation of neurogenesis during critical time windows of hippocampal development.

Postnatal neurogenesis in the hippocampal dentate gyrus and subventricular zone of the Göttingen minipig

Postnatal neurogenesis is currently viewed as important for neuroplasticity and brain repair. We are, therefore, interested in animal models for neuroimaging of postnatal neurogenesis. A recent stereological study found an age-dependent increase in the number of neurons and glial cells in the neocortex of Göttingen minipigs, suggesting that this species may be characterized by a prolonged postnatal neurogenesis. Since there is no direct evidence on this issue, the goal of our study was to quantify cell proliferation in the two major neurogenic regions of the postnatal brain - the subventricular zone of the lateral ventricle (SVZ) and the hippocampal dentate gyrus (DG) - at two separate points during the lifespan of the minipig. Göttingen minipigs aged 6-7 and 32 weeks were injected with bromodeoxyuridine (BrdU), a marker of cycling cells, and killed after 2h. We found BrdU-positive cells numbering 165,000 in the SVZ and 35,000 in the DG at 6-7 weeks and 66,000 in the SVZ and 19,000 in the DG at 32 weeks-of-age. Stereology showed a 60% increase in the total number of DG granule cells between 6-7 and 32 weeks-of-age. Our findings show a continued postnatal neurogenesis in the major neurogenic regions of Göttingen minipigs, thereby providing a potential animal model for studies aimed at examining ongoing neurogenesis in the living brain with molecular neuroimaging technology.

APP-dependent up-regulation of Ptch1 underlies proliferation impairment of neural precursors in Down syndrome

Mental retardation in Down syndrome (DS) appears to be related to severe neurogenesis impairment during critical phases of brain development. Recent lines of evidence in the cerebellum of a mouse model for DS (the Ts65Dn mouse) have shown a defective responsiveness to Sonic Hedgehog (Shh), a potent mitogen that controls cell division during brain development, suggesting involvement of the Shh pathway in the neurogenesis defects of DS. Based on these premises, we sought to identify the molecular mechanisms underlying derangement of the Shh pathway in neural precursor cells (NPCs) from Ts65Dn mice. By using an in vitro model of NPCs obtained from the subventricular zone and hippocampus, we found that trisomic NPCs had an increased expression of the Shh receptor Patched1 (Ptch1), a membrane protein that suppresses the action of a second receptor, Smoothened (Smo), thereby maintaining the pathway in a repressed state. Partial silencing of Ptch1 expression in trisomic NPCs restored cell proliferation, indicating that proliferation impairment was due to Ptch1 overexpression. The overexpression of Ptch1 in trisomic NPCs resulted from increased levels of AICD [a transcription-promoting fragment of amyloid precursor protein (APP)] and increased AICD binding to the Ptch1 promoter. Our data provide novel evidence that Ptch1 overexpression underlies derangement of the Shh pathway in trisomic NPCs with consequent proliferation impairment. The demonstration that Ptch1 overexpression in trisomic NPCs is due to an APP fragment provides a link between this trisomic gene and the defective neuronal production that characterizes the DS brain.

Widespread proliferation impairment and hypocellularity in the cerebellum of fetuses with down syndrome

Evidence in mouse models for Down syndrome (DS) and human fetuses with DS clearly shows severe neurogenesis impairment in various telencephalic regions, suggesting that this defect may underlie the cognitive abnormalities of DS. As cerebellar hypotrophy and motor disturbances are part of the clinical features of DS, the goal of our study was to establish whether these defects may be related to neurogenesis impairment during cerebellar development. We found that in fetuses with DS (17-21 weeks of gestation) the cerebellum had an immature pattern, a reduced volume and notably fewer cells (-25%/-50%) in all cerebellar layers. Immunohistochemistry for Ki-67, a marker of cycling cells, showed impaired proliferation (-17%/-50%) of precursors from both cerebellar neurogenic regions (external granular layer and ventricular zone). No differences in apoptotic cell death were found in DS vs. control fetuses. The current study provides novel evidence that in the cerebellum of DS fetuses there is a generalized hypocellularity and that this defect is due to proliferation impairment, rather than to an increased cell death. The reduced proliferation potency found in the DS fetal cerebellum, in conjunction with previous evidence, strengthens the idea that the trisomic brain is characterized by widespread neurogenesis disruption.

Predictive parameters after molecular absorbent recirculating system treatment integrated with model for end stage liver disease model in patients with acute-on-chronic liver failure

AIM

The aim of study was to highlight parameters that in association with Model for End-stage Liver Disease (MELD) provide predictive criteria for long-term survival after treatment with the Molecular Adsorbent Recirculating System (MARS). Two homogenous groups were studied: one treated with standard medical therapy (SMT) and the other, with MARS.

MATERIALS AND METHODS

Twenty acute-on-chronic liver failure patients on the waiting list for liver transplantation and affected by alcoholic cirrhosis with similar MELD scores (20-29) were evaluated for 7 days from inclusion and for 6-month survival. Ten patients (seven males and three females) were treated with MARS. Their mean age was 48.5 years (range = 35-61). The number of MARS applications was six for 6 consecutive days, and the length of the applications was 8 hours. Ten other patients (seven males and three females) were treated with SMT, including prophylaxis against bacterial infections and judicious use of diuretics. The precipitating factors were also treated appropriately. The mean age of the patients was 51 years (range = 37-64). All the variables that were significant upon univariate analysis were enrolled in a receiver operating characteristic analysis, with the intention to detect predictive parameters for patient death at 6 months. We considered a significant area under curve (AUC) value to be greater than 0.5.

RESULTS

Among 11 patients who died within 6 months there were in the MARS group and eight in the SMT group: the 3- and 6-month patient survival rates were 90% and 70% versus 30% and 20% in the two groups, respectively. Nine measures resulted in an AUC > 0.5: DeltaMELD; interleukin (IL)-8; IL-6; tumor necrosis factor- alpha, MELD score; creatinine, bilirubin international normalized ratio (INR) and cardiac index. DeltaMELD and postoperative IL-8 concentrations showed better results (AUC = 0.899), followed by postoperative creatinine (AUC = 0.879), postoperative cardiac index (AUC = 0.833), and postoperative INR (AUC = 0.818). Postoperative creatinine showed the best sensitivity (100%), while IL-8, the best specificity (88.9%).

CONCLUSION

A combination of biochemical and clinical variables probably represent the best way to predict the survival of patients, allowing physicians to select the best therapies for each patient.

Changes in hippocampal morphology and neuroplasticity induced by adolescent THC treatment are associated with cognitive impairment in adulthood

Marijuana and hashish are the illicit drugs most frequently used by human adolescents. Given the continued neurodevelopment throughout adolescence, adolescents may be more vulnerable than adults to certain neural consequences of heavy marijuana use. This study aimed to assess whether an experimental model of adolescent chronic exposure to Delta9-tetrahydrocannabinol (THC), may induce lasting effects on learning and memory. Adolescent rats have been treated with THC or its vehicle from 35 to 45 postnatal days (PND) and left undisturbed until their adulthood (75 PND) when aversive and spatial memory was assessed using the passive avoidance and radial maze tasks. No alteration was found in aversive memory, but in the radial maze THC pretreated animals exhibited a worse performance than vehicles, suggesting a deficit in spatial working memory. To correlate memory impairment to altered neuroplasticity, level of marker proteins was investigated in the hippocampus, the most relevant area mediating spatial memory. A significant decrease in the astroglial marker glial fibrillar acid protein was found as well as in pre- and postsynaptic protein expression (VAMP2, PSD95) and NMDA receptor levels in pretreated rats. To parallel these changes to alteration in dendritic morphology, Golgi-Cox staining was performed in the hippocampal dentate gyrus. Pretreated rats had a significantly lower total dendritic length and number than vehicles, as well as reduced spine density. Our data suggest that THC pretreated rats may establish less synaptic contacts and/or less efficient synaptic connections throughout the hippocampus and this could represent the molecular underpinning of the cognitive deficit induced by adolescent THC treatment.

Lithium restores neurogenesis in the subventricular zone of the Ts65Dn mouse, a model for Down syndrome

Down syndrome (DS), a high-incidence genetic pathology, involves brain hypoplasia and mental retardation. Emerging evidence suggests that reduced neurogenesis may be a major determinant of brain underdevelopment in DS. To establish whether it is possible to improve neurogenesis in DS, Ts65Dn mice--the most widely used model for DS--and euploid mice were treated with control or lithium chow for 1 month. During the last 3 days animals received one daily injection of 5-bromo-2-deoxyuridine (BrdU)--a marker of proliferating cells--and were sacrificed 24 h after the last injection. Neurogenesis was examined in the subventricular zone (SVZ), a region that retains a neurogenic potential across life. We found that Ts65Dn mice had less (-40%) BrdU+ cells than euploid mice, indicating severe proliferation impairment. Treatment with lithium increased the number of Brdu+ cells in both euploid and Ts65Dn mice. In the latter the number of Brdu+ cells became similar to that of untreated euploid mice. Our study shows that lithium is able to restore cell proliferation in the SVZ of the Ts65Dn mouse and point at treatments with mood stabilizers as a potential tool to improve neurogenesis in patients with DS.

Molecular epidemiological investigation of an outbreak of Pseudomonas aeruginosa infection in an SCT unit

From May to October 2006, six severe Pseudomonas aeruginosa infections were diagnosed in patients undergoing SCT in the SCT unit of the Careggi hospital (Florence, Italy). Four of the infected patients were treated consecutively in the same room (room N). On the hypothesis of a possible environmental source of infection, samples were collected from different sites that had potential for cross-contamination throughout the SCT unit, including the electrolytic chloroxidant disinfectant used for hand washing (Irgasan) and the disinfectant used for facilities cleaning. Four of the environmental samples were positive for P. aeruginosa: three Irgansan soap samples and a tap swab sample from the staff cleaning and dressing room. The AFLP (amplified fragment length polymorphism) typing method employed to evaluate strain clonality showed that the isolates from the patients who had shared the same room and an isolate from Irgasan soap had a significant molecular similarity (dice index higher than 0.93). After adequate control measures, no subsequent environmental sample proved positive for P. aeruginosa. These data strongly support the hypothesis of the clonal origin of the infective strains and suggest an environmental source of infection. The AFLP method was fast enough to allow a 'real-time' monitoring of the outbreak, permitting additional preventive measures.

Acute hepatitis B in patients with or without underlying chronic HCV infection

BACKGROUND AND AIM

Acute hepatitis B course may be significantly modified by underlying chronic hepatitis C. The aim of this study was to compare clinical and virological characteristics of acute hepatitis B in patients with or without chronic hepatitis C virus (HCV) infection.

MATERIALS AND METHODS

Twenty-seven patients with symptomatic acute hepatitis B were enrolled: 14 with underlying chronic HCV (Group A) and 13, matched by age and gender, with single hepatitis B (Group B). All patients were followed-up until HBsAg negativization.

RESULTS

Group A patients were HCV-RNA-negative on hospital admission and all but one remained negative during follow-up. HBeAg tested positive in 92.9% and 84.6% of Groups A and B patients, respectively. ALT, bilirubin, prothrombin time values and HBsAg titer were similar in both groups. Nevertheless, lower mean HBV-DNA levels (p=0.03), a shorter duration of HBsAg positivity (p<0.01) and of symptoms before ALT peak (p=0.014), and significantly lower peak ALT values (p=0.03) were observed in Group A compared to Group B patients.

CONCLUSIONS

Acute HBV infection suppressed HCV replication. Conversely, the underlying HCV infection exerted a modulatory effect on HBV replication which influenced the course, though not the outcome, of the acute disease. Although acute hepatitis B showed a mild clinical course in both groups of patients, HBV vaccination should be suggested to risk subjects.