Role of fragile X messenger ribonucleoprotein 1 in the pathophysiology of brain disorders: a glia perspective.

Fragile X messenger ribonucleoprotein 1 (FMRP) is a widely expressed RNA binding protein involved in several steps of mRNA metabolism. Mutations in the FMR1 gene encoding FMRP are responsible for fragile X syndrome (FXS), a leading genetic cause of intellectual disability and autism spectrum disorder, and fragile X-associated tremor-ataxia syndrome (FXTAS), a neurodegenerative disorder in aging men. Although FMRP is mainly expressed in neurons, it is also present in glial cells and its deficiency or altered expression can affect functions of glial cells with implications for the pathophysiology of brain disorders. The present review focuses on recent advances on the role of glial subtypes, astrocytes, oligodendrocytes and microglia, in the pathophysiology of FXS and FXTAS, and describes how the absence or reduced expression of FMRP in these cells can impact on glial and neuronal functions. We will also briefly address the role of FMRP in radial glial cells and its effects on neural development, and gliomas and will speculate on the role of glial FMRP in other brain disorders.

Fragile X mental retardation protein (FMRP) and metabotropic glutamate receptor subtype 5 (mGlu5) control stress granule formation in astrocytes.

Fragile X syndrome (FXS) is a common form of intellectual disability and autism caused by the lack of Fragile X Mental Retardation Protein (FMRP), an RNA-binding protein involved in RNA transport and protein synthesis. Upon cellular stress, global protein synthesis is blocked and mRNAs are recruited into stress granules (SGs), together with RNA-binding proteins including FMRP. Activation of group-I metabotropic glutamate (mGlu) receptors stimulates FMRP-mediated mRNA transport and protein synthesis, but their role in SGs formation is unexplored. To this aim, we pre-treated wild type (WT) and Fmr1 knockout (KO) cultured astrocytes with the group-I-mGlu receptor agonist (S)-3,5-Dihydroxyphenylglycine (DHPG) and exposed them to sodium arsenite (NaAsO2), a widely used inducer of SGs formation. In WT cultures the activation of group-I mGlu receptors reduced SGs formation and recruitment of FMRP into SGs, and also attenuated phosphorylation of eIF2α, a key event crucially involved in SGs formation and inhibition of protein synthesis. In contrast, Fmr1 KO astrocytes, which exhibited a lower number of SGs than WT astrocytes, did not respond to agonist stimulation. Interestingly, the mGlu5 receptor negative allosteric modulator (NAM) 2-methyl-6-(phenylethynyl)pyridine (MPEP) antagonized DHPG-mediated SGs reduction in WT and reversed SGs formation in Fmr1 KO cultures. Our findings reveal a novel function of mGlu5 receptor as modulator of SGs formation and open new perspectives for understanding cellular response to stress in FXS pathophysiology.

Fragile X mental retardation protein (FMRP) interacting proteins exhibit different expression patterns during development.

Fragile X syndrome is caused by the lack of expression of fragile X mental retardation protein (FMRP), an RNA-binding protein involved in mRNA transport and translation. FMRP is a component of mRNA ribonucleoprotein complexes and it can interact with a range of proteins either directly or indirectly, as demonstrated by two-hybrid selection and co-immunoprecipitation, respectively. Most of FMRP-interacting proteins are RNA-binding proteins such as FXR1P, FXR2P and 82-FIP. Interestingly, FMRP can also interact directly with the cytoplasmic proteins CYFIP1 and CYFIP2, which do not bind RNA and link FMRP to the RhoGTPase pathway. The interaction with these different proteins may modulate the functions of FMRP by influencing its affinity to RNA and by affecting the FMRP ability of cytoskeleton remodeling through Rho/Rac GTPases. To better define the relationship of FMRP with its interacting proteins during brain development, we have analyzed the expression pattern of FMRP and its interacting proteins in the cortex, striatum, hippocampus and cerebellum at different ages in wild type (WT) mice. FMRP and FXR2P were strongly expressed during the first week and gradually decreased thereafter, more rapidly in the cerebellum than in the cortex. FXR1P was also expressed early and showed a reduction at later stages of development with a similar developmental pattern in these two regions. CYFIP1 was expressed at all ages and peaked in the third post-natal week. In contrast, CYFIP2 and 82-FIP (only in forebrain regions) were moderately expressed at P3 and gradually increased after P7. In general, the expression pattern of each protein was similar in the regions examined, except for 82-FIP, which exhibited a strong expression at P3 and low levels at later developmental stages in the cerebellum. Our data indicate that FMRP and its interacting proteins have distinct developmental patterns of expression and suggest that FMRP may be preferentially associated to certain proteins in early and late developmental periods. In particular, the RNA-binding and cytoskeleton remodeling functions of FMRP may be differently modulated during development.

Glutamate binding-site ligands of NMDA receptors.

Excitatory neurotransmission mediated by NMDA (N-methyl-D-aspartic acid) receptors plays a key role in both healthy and diseased processes in the brain. Therefore, bioactive compounds that can interact selectively with these receptors have been the aim of extensive research in the search of effective therapeutic agents or, at least, useful pharmacological tools. NMDA receptors are heteromeric ion channels that contain different modulatory sites capable to bind subunit-selective ligands. In particular, the activation of NMDA receptors requires two distinct ligands: glutamate (the endogenous agonist) and glycine (the co-agonist). In view of the renewed interest in this research area and the high therapeutic potential of this target, this review presents an updated survey of ligands which interact with the glutamate binding-site of the NMDA receptors, their rational development, and data on the structure-activity relationship which are of utmost importance for the design of novel lead compounds.

High frequency of Chlamydophila pneumoniae infections: patients with peripheral arterial disease and those with risk factors for cardiovascular diseases compared to normal subjects.

The role of bacterial infections, mainly Chlamydophila pneumoniae, on atherosclerotic processes as well as the therapeutic utility of additional antibiotic treatment is still an open question. In this study we compared the serological profiles of 160 patients (80 with peripheral arterial disease (PAD), diagnosed with an ankle/brachial index (ABI) ≤ 0.9 and 80 with risk factors for cardiovascular disease - CVD) with those of 80 healthy subjects, serum levels of specific C. pneumoniae antibodies using the microimmunofluorescence test. Our results show that PAD patients had a higher frequency of C. pneumoniae infection than those with risk factors for cardiovascular disease. This frequency was lower if compared to the previous two groups in controls. 44 out of the 80 (55%) patients with PAD and 34 out of the 80 (42.58%) subjects with risk factors for cardiovascular disease were seropositive while only 24 of the 80 (30%) healthy subjects showed seropositivity to C. pneumoniae. Furthermore, higher anticorpal titers were also found in patients with peripheral arterial disease and in patients with cardiovascular risk factors if compared to healthy subjects. On the basis of these results, we confirm that C. pneumoniae infection is frequent in peripheral arterial disease patients and we believe that it could be considered as an additional risk factor involved in the pathogenesis of this disease.

European Confederation of Medical Mycology (ECMM) prospective survey of candidaemia: report from one Italian region.

An ECMM epidemiological prospective survey of candidaemia was performed in one Italian region (Lombardy; population: 8 924 870) by the National Society of Medical Mycology (FIMUA) from September 1997 to December 1999. In total, 569 episodes were reported with an overall rate of 0.38/1000 admissions, 4.4/100000 patient days. Predisposing factors included presence of an intravascular catheter (89%), antibiotic treatment (88%), surgery (56%), intensive care (45%), solid tumour (28%), steroid treatment (15%), haematological malignancy (7%), HIV infection (6%), fetal immaturity (4%). Mucous membrane colonization preceded candidaemia in 83% of patients. Candida albicans was identified in 58% of cases, followed by Candida parapsilosis (15%), Candida glabrata (13%), Candida tropicalis (6%). Septic shock occurred in 95 patients. Crude mortality was 35%, the highest in C. tropicalis fungaemia (44%), the elderly (64%) and solid tumour cancer patients (43%). Intravascular catheter removal was associated with higher survival rate (71 vs. 47%). This survey underscores the importance of candidaemia in hospital settings.

Long-term angiographic follow-up after successful repeat balloon angioplasty for in-stent restenosis.

BACKGROUND: Coronary stent implantation is associated with improved angiographic short-term and mid-term clinical outcome. However, restenosis rate still remains between 20 and 30%. HYPOTHESIS: The purpose of the study, performed as a prospective angiographic follow-up to detect restenosis, was to evaluate the immediate and the 6-month angiographic results of repeat balloon angioplasty for in-stent restenosis. METHODS: From April 1996 to September 1997, 335 stenting procedures performed in 327 patients underwent prospectively 6-month control angiography. Of the 96 lesions that showed in-stent restenosis (> 50% diameter stenosis) (29%), 72 underwent balloon angioplasty. RESULTS: The primary success rate was 100%. Follow-up angiogram at a mean of 6.9 +/- 2.4 months was obtained in 54 patients. Recurrent restenosis was observed in 24 of the 55 stents (44%). Repeat intervention for diffuse and body location in-stent restenosis before repeat intervention was associated with significantly higher rates of recurrent restenosis (p < 0.001 and p < 0.05, respectively). Of the 19 patients who underwent further balloon angioplasty (100% success rate), coronary angiography was performed in 18 (95%) at a mean of 8.2 +/- 2.0 months and showed recurrent restenosis in 12 patients (67%). Further repeat intervention for diffuse and severe in-stent restenosis before the second repeat intervention was associated with significantly higher rates of further recurrent restenosis (p < 0.05 and p < 0.005, respectively). CONCLUSIONS: Although balloon angioplasty can be safely, successfully, and repeatedly performed after stent restenosis, it carries a progressively high recurrence of angiographic restenosis rate during repeat 6-month follow-ups. The subgroup of patients with diffuse, severe, and/or body location in-stent restenosis proved to be at higher risk of recurrent restenosis.

Cryptococcus neoformans infection in a cohort of Italian AIDS patients: natural history, early prognostic parameters, and autopsy findings.

This observational cohort study of 4,160 AIDS patients hospitalised in a single institution in northern Italy between January 1985 and December 1999 was carried out in order to assess the natural history of cryptococcosis, the epidemiological trend of this opportunistic infection, the risk factors predictive of death at 10 weeks, the response to therapy, and autopsy findings. Cryptococcosis was diagnosed in 177 (4.2%) patients and was the AIDS-defining disease in 2.8% of cases. Its prevalence decreased significantly over time (from 6.4% in the period 1985-1989 to 5.7% in 1990-1993, 3.1% in 1994-1996, and 1.9% in 1997-1999, P <0.0001). Although neurologic disease was the most frequent clinical picture, a significant proportion of the patients (24.2%) presented with extraneural cryptococcosis. In a Cox multivariate analysis, high titres of cerebrospinal fluid antigen (>5000) and drug addiction were predictive of death at 10 weeks. A complete clinical and mycological response was achieved in 60.8% of the treated patients, with the highest response rate being observed in those treated with amphotericin plus flucytosine (66.6%). Cryptococcosis relapsed in 12.8% of patients on secondary prophylaxis. Autopsy findings demonstrated that cryptococcosis is a disseminated disease, but long-term antifungal treatment may be able to eradicate it in a subgroup of patients.

Candida albicans cellular internalization: a new pathogenic factor?

The preliminary results of a study to show the possibility that Candida albicans can internalize into epithelial cells are reported. The study was performed on buccal, vaginal and HeLa cells. Buccal and vaginal cells, at a concentration of 5 x 10(4) cells/ml and HeLa monolayers were incubated for 2, 3 and 4 h with 10(5) colony forming units of a Candida albicans isolate. After incubation, non-internalised yeasts were eliminated and samples were processed for examination by Scanning Electron Microscopy. Results suggest that receptor-mediated endocytosis could be involved in the pathogenesis of recurrent oral and vaginal infections. This phenomenon could represent an interesting experimental model to testing drug interference in the development of therapeutic strategies against C. albicans infections.

[Disseminated histoplasmosis in patients with AIDS. 2 case reports]. / Istoplasmosi disseminata in pazienti affetti da AIDS. Descrizione di due casi.

Histoplasmosis is endemic in some areas of United States and in South America, and generally causes an acute self-limiting respiratory infection. In elderly and immunosuppressed patients the infection can spread through the blood, causing a severe systemic illness. Here we describe two cases of disseminated histoplasmosis in AIDS patients. The first was observed in an Italian woman who had never visited endemic countries, and was recognized only at autopsy; the second was observed in a trans-sexual patient, arrived in Italy from Brazil. Clinical suspicion of histoplasmosis is important in immunocompromised patients of non-endemic areas as symptoms are often aspecific and misdiagnosis is frequent.

Antimycotic activity and phagocytosis effects of econazole in combination with ibuprofen isobuthanolammonium against vaginal strains.

Vaginal infections caused by Candida spp., other yeasts and Trichomonas vaginalis are problematic mainly due to the various factors involved in development of infection and to the failure of common treatments. In this study we investigated the presence of synergistic activity of econazole and ibuprofen isobuthanolammonium against 310 different vaginal isolates, by using the microdilution broth assay to test in vitro antimicrobial activity and the effect of the two drugs on phagocytosis and intramacrophagic cellular killing of mouse peritoneal macrophages. The effect of sub-inhibitory concentrations of econazole / ibuprofen isobuthanolammonium combination on Candida albicans germ tube formation was also evaluated. The in vitro antifungal activity of econazole was notably improved by addition of ibuprofen isobuthanolammonium. Macrophage killing of C. albicans was significantly increased by the two drugs and also germ-tube formation was significantly affected. We conclude that the addition of ibuprofen isobuthanolammonium to econazole provides better in vitro antifungal activity. However, further studies are needed to elucidate the in vivo action of this formulation.

Faecal bacteria of wild ruminants and the alpine marmot.

Faecal samples from 60 red deer (Cervus elaphus), 13 roe deer (Capreolus capreolus), 7 chamois (Rupicapra rupicapra), 41 alpine marmot (Marmota marmota) and soils mixed with deer faeces from the Stelvio National Park were examined for Campylobacter sp. and Salmonella sp. with negative results. The same material, especially deer faeces, was a habitat highly suitable for Yersinia sp.: Y. enterocolitica (two biotypes) was isolated twice, Y. kristensenii (two serotypes) was isolated 19 times, Y. frederiksenii and Y. intermedia were isolated once. Antibiotic-resistant Escherichia coli were isolated from 16 specimens from wild ruminants, one from marmot and two from feeding places.